0000000001157303
AUTHOR
E. M. T. Puccio
Dalitz plot analyses of J/ψ→π+π−π0 , J/ψ→K+K−π0 , and J/ψ→Ks0K±π∓ produced via e+e− annihilation with initial-state radiation
We study the processes e^+e^− → γISR J/ψ, where J/ψ → π^+π^−π^0, J/ψ → K^+K^−π^0, and J/ψ → K^0_SK^±π^∓ using a data sample of 519 fb^(−1) recorded with the BABAR detector operating at the SLAC PEP-II asymmetric-energy e^+e^− collider at center-of-mass energies at and near the Υ(nS) (n=2,3,4) resonances. We measure the ratio of branching fractions R_1 = ^(B(J/ψ → K^+K^−π^0)) /_(B(J/ψ → π^+π^−π^0)) and R_2 = ^(B(J/ψ → K^0_SK^±π^∓))/_(B(J/ψ → π^+π^−π^0)). We perform Dalitz plot analyses of the three J/ψ decay modes and measure fractions for resonances contributing to the decays. We also analyze the J/ψ → π^+π^−π^0 decay using the Veneziano model. We observe structures compatible with the pres…
Search for a Stable Six-Quark State at BABAR
Recent investigations have suggested that the six-quark combination uuddss could be a deeply bound state (S) that has eluded detection so far, and a potential dark matter candidate. We report the first search for a stable, doubly strange six-quark state in Upsilon -> S anti-Lambda anti-Lambda decays based on a sample of 90 million Upsilon(2S) and 110 million Upsilon(3S) decays collected by the BABAR experiment. No signal is observed, and 90% confidence level limits on the combined Upsilon(2S,3S) -> S anti-Lambda anti-Lambda branching fraction in the range (1.2-1.4)x10^-7 are derived for m_S < 2.05 GeV. These bounds set stringent limits on the existence of such exotic particles.
Measurement of theD*(2010)+natural linewidth and theD*(2010)+−D0mass difference
We measure the mass difference, Δm_0, between the D^*(2010)^+ and the D^0 and the natural linewidth, Γ, of the transition D^*(2010)^+ → D^0π^+. The data were recorded with the BABAR detector at center-of-mass energies at and near the Υ(4S) resonance, and correspond to an integrated luminosity of approximately 477 fb^(-1). The D^0 is reconstructed in the decay modes D^0 → K^-π^+ and D^0 → K^-π^+π^-π^+. For the decay mode D^0 → K^-π^+ we obtain Γ=(83.4±1.7±1.5) keV and Δm_0=(145425.6±0.6±1.8) keV, where the quoted errors are statistical and systematic, respectively. For the D^0 → K^-π^+π^-π^+ mode we obtain Γ=(83.2±1.5±2.6) keV and Δm_0 = (145426.6±0.5±2.0) keV. The combined measurements…
Evidence for an Excess ofB¯→D(*)τ−ν¯τDecays
Based on the full BaBar data sample, we report improved measurements of the ratios R(D(*)) = B(B -> D(*) Tau Nu)/B(B -> D(*) l Nu), where l is either e or mu. These ratios are sensitive to new physics contributions in the form of a charged Higgs boson. We measure R(D) = 0.440 +- 0.058 +- 0.042 and R(D*) = 0.332 +- 0.024 +- 0.018, which exceed the Standard Model expectations by 2.0 sigma and 2.7 sigma, respectively. Taken together, our results disagree with these expectations at the 3.4 sigma level. This excess cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model. We also report the observation of the decay B -> D Tau Nu, with a significance of 6.8 sigma.
Search for a Dark Leptophilic Scalar in e(+) e(-) Collisions
Many scenarios of physics beyond the standard model predict the existence of new gauge singlets, which might be substantially lighter than the weak scale. The experimental constraints on additional scalars with masses in the MeV to GeV range could be significantly weakened if they interact predominantly with leptons rather than quarks. At an e+e- collider, such a leptophilic scalar (φL) would be produced predominantly through radiation from a τ lepton. We report herein a search for e+e-→τ+τ-φL, φL→ℓ+ℓ- (ℓ=e, μ) using data collected by the BABAR experiment at SLAC. No significant signal is observed, and we set limits on the φL coupling to leptons in the range 0.04<mφL<7.0 GeV. These bounds s…
Antideuteron production inϒ(nS)decays and ine+e−→qq¯ats≈10.58 GeV
We present measurements of the inclusive production of antideuterons in e^+e^− annihilation into hadrons at ≈10.58 GeV center-of-mass energy and in Υ(1S,2S,3S) decays. The results are obtained using data collected by the BABAR detector at the PEP-II electron-positron collider. Assuming a fireball spectral shape for the emitted antideuteron momentum, we find B(Υ(1S)→d[bar]X)=(2.81±0.49(stat)^(+0.20)_(−0.24)(syst))×10^(−5), B(Υ(2S)→d[bar]X)=(2.64±0.11(stat)^(+0.26)(−0.21)(syst))×10^(−5), B(Υ(3S)→d[bar]X)=(2.33±0.15(stat)^(+0.31)_(−0.28)(syst))×10^(−5), and σ(e^+e^− →d[bar]X)=(9.63±0.41(stat)^(+1.17)_(−1.01)(syst) fb.
Search for a low-mass scalar Higgs boson decaying to a tau pair in single-photon decays of Y(1S)
We search for a low-mass scalar CP-odd Higgs boson, A(0), produced in the radiative decay of the upsilon resonance and decaying into a tau(+)tau(-) pair: Y(1S) -> gamma A(0). The production of Y(1S) mesons is tagged by Y(2S) -> pi(+)pi(-) Y(1S) transitions, using a sample of (98.3 +/- 0.9) x 10(6) Y(2S) mesons collected by the BABAR detector. We find no evidence for a Higgs boson in the mass range 3: 5 <= m(A)0 <= 9: 2 GeV, and combine these results with our previous search for the tau decays of the light Higgs in radiative Y(3S) decays, setting limits on the coupling of A(0) to the b (b) over bar quarks in the range 0.09-1.9. Our measurements improve the constraints on the parameters of th…
Measurement of the branching fractions of the radiative leptonicτdecaysτ→eγνν¯andτ→μγνν¯atBABAR
We perform a measurement of the $\ensuremath{\tau}\ensuremath{\rightarrow}l\ensuremath{\gamma}\ensuremath{\nu}\overline{\ensuremath{\nu}}$ ($l=e,\ensuremath{\mu}$) branching fractions for a minimum photon energy of 10 MeV in the $\ensuremath{\tau}$ rest frame, using $431\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of ${e}^{+}{e}^{\ensuremath{-}}$ collisions collected at the center-of-mass energy of the $\mathrm{\ensuremath{\Upsilon}}(4S)$ resonance with the BABAR detector at the PEP-II storage rings. We find $\mathcal{B}(\ensuremath{\tau}\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\gamma}\ensuremath{\nu}\overline{\ensuremath{\nu}})=(3.69\ifmmode\pm\else\textpm\fi{}0.03\ifmmode\p…
Time-dependent analysis ofB0→KS0π−π+γdecays and studies of theK+π−π+system inB+→K+π−π+γdecays
This work is supported by the U.S. Department of Energy and National Science Foundation, the Natural Sciences and Engineering Research Council (Canada), the Commissariat a l’Energie Atomique and Institut National de Physique Nucleaire et de Physique des Particules (France), the Bundesministerium fur Bildung und Forschung and Deutsche Forschungsgemeinschaft (Germany), the Istituto Nazionale di Fisica Nucleare (Italy), the Foundation for Fundamental Research on Matter (Netherlands), the Research Council of Norway, the Ministry of Education and Science of the Russian Federation, Ministerio de Ciencia e Innovacion (Spain), and the Science and Technology Facilities Council (United Kingdom). Indi…
Exclusive initial-state-radiation production of theDD¯,D*D¯, andD*D¯*systems
We perform a study of the exclusive production of in initial-state-radiation events, from e(+)e(-) annihilations at a center-of-mass energy near 10.58 GeV, to search for charmonium and possible new resonances. The data sample corresponds to an integrated luminosity of 384 fb(-1) and was recorded by the BABAR experiment at the PEP-II storage rings. The D (D) over bar, D*(D) over bar, D*(D) over bar* mass spectra show clear evidence of several psi resonances. However, there is no evidence for Y(4260) -> D*(D) over bar or Y(4260) -> D*(D) over bar*.
Search for Long-Lived Particles ine+e−Collisions
We present a search for a neutral, long-lived particle L that is produced in e^+e^− collisions and decays at a significant distance from the e^+e^− interaction point into various flavor combinations of two oppositely charged tracks. The analysis uses an e^+e^− data sample with a luminosity of 489.1 fb^(−1) collected by the BABAR detector at the Υ(4S), Υ(3S), and Υ(2S) resonances and just below the Υ(4S). Fitting the two-track mass distribution in search of a signal peak, we do not observe a significant signal, and set 90% confidence level upper limits on the product of the L production cross section, branching fraction, and reconstruction efficiency for six possible two-body L decay modes …
Measurement of the D*(2010)+−D+ Mass Difference
We measure the mass difference, Δm_{+}, between the D^{*}(2010)^{+} and the D^{+} using the decay chain D^{*}(2010)^{+}→D^{+}π^{0} with D^{+}→K^{-}π^{+}π^{+}. The data were recorded with the BABAR detector at center-of-mass energies at and near the ϒ(4S) resonance, and correspond to an integrated luminosity of approximately 468 fb^{-1}. We measure Δm_{+}=(140 601.0±6.8[stat]±12.9[syst]) keV. We combine this result with a previous BABAR measurement of Δm_{0}≡m(D^{*}(2010)^{+})-m(D^{0}) to obtain Δm_{D}=m(D^{+})-m(D^{0})=(4824.9±6.8[stat]±12.9[syst]) keV. These results are compatible with and approximately five times more precise than the Particle Data Group averages.
Bmeson decays to charmless meson pairs containingηorη′mesons
We present updated measurements of the branching fractions for B-0 meson decays to eta K-0, eta eta, eta phi, eta omega, eta K-'(0), eta(')eta('), eta(')phi, and eta(')omega, and branching fractions and CP-violating charge asymmetries for B+ decays to eta pi(+), eta K+, eta(')pi(+), and eta K-'(+). The data represent the full data set of 467x10(6) BB pairs collected with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider at the SLAC National Accelerator Laboratory. Besides large signals for the four charged B decay modes and for B-0 ->eta K-'(0), we find evidence for three B-0 decay modes at greater than 3.0 sigma significance. We find B(B-0 ->eta K-0)=(1.15(-0.38)(+0.43)+…
Tests ofCPTsymmetry inB0−B¯0mixing and inB0→cc¯K0decays
Using the eight time dependences for the decays Upsilon(4S)-> B0 B0bar -> fj fk with the dacay into a flavor-specific state fj = ell+- X before or after the decay into a CP eigenstate fk = c cbar KS,KL, as measured by the BABAR experiment, we determine the three CPT-sensitive parameters Re(z) and Im(z) in B0-B0bar mixing and |Abar/A| in B0 -> c cbar K0 decays. We find Im(z) = 0.010 +- 0.030 +- 0.013, Re(z) = -0.065 +- 0.028 +- 0.014, and |Abar/A| = 0.999 +- 0.023 +- 0.017, in agreement with CPT symmetry.
Evidence for DirectCPViolation in the Measurement of the Cabbibo-Kobayashi-Maskawa AngleγwithB∓→D(*)K(*)∓Decays
We report the measurement of the Cabibbo-Kobayashi-Maskawa CP-violating angle {gamma} through a Dalitz plot analysis of neutral D meson decays to K{sub S}{sup 0}{pi}{sup +}{pi}{sup -} and K{sub S}{sup 0} K{sup +}K{sup -} produced in the processes B{sup {-+}} {yields} DK{sup {-+}}, B{sup {-+}} {yields} D* K{sup {-+}} with D* {yields} D{pi}{sup 0}, D{gamma}, and B{sup {-+}} {yields} DK*{sup {-+}} with K*{sup {-+}} {yields} K{sub S}{sup 0}{pi}{sup {-+}}, using 468 million B{bar B} pairs collected by the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at SLAC. We measure {gamma} = (68 {+-} 14 {+-} 4 {+-} 3){sup o} (modulo 180{sup o}), where the first error is statistica…
Dalitz plot analysis ofB±→π±π±π∓decays
We present a Dalitz plot analysis of charmless B-+/- decays to the final state pi(+/-)pi(+/-)pi(-/+) using a sample of (465 +/- 5)x10(6) B(B)over bar pairs collected by the BABAR experiment at root s=10.58 GeV. We measure the branching fractions B(B-+/-->pi(+/-)pi(+/-)pi(-/+))=(15.2 +/- 0.6 +/- 1.2 +/- 0.4)x10(-6), B(B-+/-->rho(0)(770)pi(+/-))=(8.1 +/- 0.7 +/- 1.2(-1.1)(+0.4))x10(-6), B(B-+/--> f(2)(1270)pi(+/-))=(1.57 +/- 0.42 +/- 0.16(-0.19)(+0.53))x10(-6), and B(B-+/-->pi(+/-)pi(+/-)pi(-/+) nonresonant)=(5.3 +/- 0.7 +/- 0.6(-0.5)(+1.1))x10(-6), where the uncertainties are statistical, systematic, and model-dependent, respectively. Measurements of branching fractions for the modes B-+/-->…
Evidence ofB+→τ+νdecays with hadronicBtags
We present a search for the decay B+→τ+ν using 467.8×10^6 BB pairs collected at the Υ(4S) resonance with the BABAR detector at the SLAC PEP-II B-Factory. We select a sample of events with one completely reconstructed B- in the hadronic decay mode (B-→D(*)0X- and B-→J/ψX-). We examine the rest of the event to search for a B+→τ+ν decay. We identify the τ+ lepton in the following modes: τ+→e+νν , τ+→μ+νν , τ+→π+ν and τ+→ρ+ν . We find an excess of events with respect to the expected background, which excludes the null signal hypothesis at the level of 3.8σ (including systematic uncertainties) and corresponds to a branching fraction value of B(B+→τ+ν)=(1.83_(-0.49)^(+0.53)(stat)±0.24(syst))×10^(…
Measurement of the neutralDmeson mixing parameters in a time-dependent amplitude analysis of theD0→π+π−π0decay
We measure the $D^0 - {\bar{D}}^0$ mixing parameters using a time-dependent amplitude analysis of the decay $D^0\to\pi^+\pi^-\pi^0$. The data were recorded with the BABAR detector at center-of-mass energies at and near the $\Upsilon(4S)$ resonance, and correspond to an integrated luminosity of approximately 468.1 ${\rm fb}^{-1}$. The neutral $D$ meson candidates are selected from $D^{*}(2010)^+\to D^0 \pi_s^+$ decays where the flavor at the production is identified by the charge of the low momentum pion, $\pi_s^+$. The measured mixing parameters are $x = (1.5\pm1.2\pm0.6) \%$ and $y = (0.2\pm0.9\pm0.5) \%$, where the quoted uncertainties are statistical and systematic, respectively.
Bottomonium spectroscopy and radiative transitions involving theχbJ(1P,2P)states atBaBar
We use (121±1) million Υ(3S) and (98±1) million Υ(2S) mesons recorded by the BABAR detector at the PEP-II e^+e^− collider at SLAC to perform a study of radiative transitions involving the χ_(bJ)(1P,2P) states in exclusive decays with μ^+μ^−γγ final states. We reconstruct twelve channels in four cascades using two complementary methods. In the first we identify both signal photon candidates in the electromagnetic calorimeter (EMC), employ a calorimeter timing-based technique to reduce backgrounds, and determine branching-ratio products and fine mass splittings. These results include the best observational significance yet for the χ_(b0)(2P)→γΥ(2S) and χ_(b0)(1P)→γΥ(1S) transitions. In the se…
Search for a Dark Photon ine+e−Collisions atBaBar
Dark sectors charged under a new Abelian interaction have recently received much attention in the context of dark matter models. These models introduce a light new mediator, the so-called dark photon (A^{'}), connecting the dark sector to the standard model. We present a search for a dark photon in the reaction e^{+}e^{-}→γA^{'}, A^{'}→e^{+}e^{-}, μ^{+}μ^{-} using 514 fb^{-1} of data collected with the BABAR detector. We observe no statistically significant deviations from the standard model predictions, and we set 90% confidence level upper limits on the mixing strength between the photon and dark photon at the level of 10^{-4}-10^{-3} for dark photon masses in the range 0.02-10.2 GeV. W…
Improved limits onB0decays to invisible(+γ)final states
We establish improved upper limits on branching fractions for B-0 decays to final states where the decay products are purely invisible (i.e., no observable final state particles) and for final states where the only visible product is a photon. Within the Standard Model, these decays have branching fractions that are below the current experimental sensitivity, but various models of physics beyond the Standard Model predict significant contributions for these channels. Using 471 x 10(6) B (B) over bar pairs collected at the Upsilon(4S) resonance by the BABAR experiment at the PEP-II e(+)e(-) storage ring at the SLAC National Accelerator Laboratory, we establish upper limits at the 90% confide…
Measurement and interpretation of moments in inclusive semileptonic decays ¯¯¯B→Xcℓ−¯ν
We present results for the moments of observed spectra in inclusive semileptonic B-meson decays to charm hadrons (B) over bar -> X(c)l(-)(nu) over bar. Moments of the hadronic-mass and the combined mass-and-energy spectra for different minimum electron or muon momenta between 0.8 and 1: 9 GeV/c are obtained from a sample of 232 X 10(6) Gamma(4S) -> B (B) over bar events, collected with the BABAR detector at the PEP-II asymmetric-energy B-meson factory at SLAC. We also present a reevaluation of the moments of electron-energy spectra and partial decay fractions B((B) over bar -> X(c)e(-)(nu) over bar) for minimum electron momenta between 0.6 and 1: 5 GeV/c based on a sample of 51 X 10(6) Gamm…
First Evidence for cos2β>0 and Resolution of the Cabibbo-Kobayashi-Maskawa Quark-Mixing Unitarity Triangle Ambiguity
We present first evidence that the cosine of the CP-violating weak phase 2β is positive, and hence exclude trigonometric multifold solutions of the Cabibbo-Kobayashi-Maskawa (CKM) Unitarity Triangle using a time-dependent Dalitz plot analysis of B^{0}→D^{(*)}h^{0} with D→K_{S}^{0}π^{+}π^{-} decays, where h^{0}∈{π^{0},η,ω} denotes a light unflavored and neutral hadron. The measurement is performed combining the final data sets of the BABAR and Belle experiments collected at the ϒ(4S) resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain (471±3)×10^{6}BB[over ¯] pairs recorded by the BABAR detector and (772±11)×10^{6}BB[over ¯] p…
Searches for rare or forbidden semileptonic charm decays
We present searches for rare or forbidden charm decays of the form $X_c^+\to h^\pm\ell^\mp\ell^{(\prime)+}$, where $X_c^+$ is a charm hadron ($D^+$, $D^+_s$, or $\Lambda_c^+$), $h^\pm$ is a pion, kaon, or proton, and $\ell^{(\prime)\pm}$ is an electron or muon. The analysis is based on $384 fb^{-1}$ of $e^+e^-$ annihilation data collected at or close to the $\Upsilon(4S)$ resonance with the BaBar detector at the SLAC National Accelerator Laboratory. No significant signal is observed for any of the 35 decay modes that are investigated. We establish 90% confidence-level upper limits on the branching fractions between $1 \times 10^{-6}$ and $44 \times 10^{-6}$ depending on the channel. In most…
Search for the rare leptonic decaysB+→l+νl(l=e,μ)
We have performed a search for the rare leptonic decays B+ -> l(+) nu(l)(l = e, mu), using data collected at the Upsilon(4S) resonance by the BABAR detector at the PEP-II storage ring. In a sample of 468 x 10(6) B (B) over bar pairs we find no evidence for a signal and set an upper limit on the branching fractions B(B+ -> mu(+)nu(mu)) e(+) nu(e)) < 1.9 x 10(-6) at the 90% confidence level, using a Bayesian approach.
Evidence for the decayB0→ωωand search forB0→ωϕ
We describe searches for B meson decays to the charmless vector-vector final states ωω and ωϕ with 471 × 10^6B¯B pairs produced in e^+e^− annihilation at √s = 10.58 GeV using the BABAR detector at the PEP-II collider at the SLAC National Accelerator Laboratory. We measure the branching fraction β(B^0 → ωω) = (1.2 ± 0.3^(+0.3)_(-0.2) × 10^(−6), where the first uncertainty is statistical and the second is systematic, corresponding to a significance of 4.4 standard deviations. We also determine the upper limit β(B^0 → ωω) < 0.7 × 10^(−6) at 90% confidence level. These measurements provide the first evidence for the decay B^0 → ωω, and an improvement of the upper limit for the decay B^0 → ωϕ.
Search for Dimuon Decays of a Light Scalar Boson in Radiative Transitions Υ→γA0
We search for evidence of a light scalar boson in the radiative decays of the {Upsilon}(2S) and {Upsilon}(3S) resonances: {Upsilon}(2S, 3S) {yields} {gamma}A{sup 0}, A{sup 0} {yields} {mu}{sup +}{mu}{sup -}. Such a particle appears in extensions of the Standaard Model, where a light CP-odd Higgs boson naturally couples strongly to b-quarks. We find no evidence for such processes in the mass range 0.212 {<=} m{sub A{sup 0}} {<=} 9.3 GeV in the samples of 99 x 10{sup 6} {Upsilon}(2S) and 122 x 10{sup 6} {Upsilon}(3S) decays collected by the BABAR detector at the PEP-II B-factory and set stringent upper limits on the effective coupling of the b quark to the A{sup 0}. We also limit the dimuon b…
Measurement of the time-dependentCPasymmetry of partially reconstructedB0→D*+D*−decays
We present a new measurement of the time-dependent CP asymmetry of B0->D*+D*- decays using (471+-5) million BBbar pairs collected with the BaBar detector at the PEP-II B Factory at the SLAC National Accelerator Laboratory. Using the technique of partial reconstruction, we measure the time-dependent CP asymmetry parameters S=-0.34+-0.12+-0.05$ and C=+0.15+-0.09+-0.04. Using the value for the CP-odd fraction R_perp=0.158+-0.028+-0.006, previously measured by BaBar with fully reconstructed B0->D*+D*- events, we extract the CP-even components S+=-0.49+-0.18+-0.07+-0.04 and C+=+0.15+-0.09+-0.04. In each case, the first uncertainty is statistical and the second is systematic; the third uncertaint…
Search for newπ0-like particles produced in association with aτ-lepton pair
We report on a search in e^+e^− annihilations for new π^0-like particles produced in association with a τ-lepton pair. These objects, with a similar mass and similar decay modes to π^0 mesons, could provide an explanation for the non-asymptotic behavior of the pion-photon transition form factor observed by the BABAR Collaboration. No significant signal is observed, and limits on the production cross section at the level of 73 fb or 370 fb, depending on the model parameters, are determined at 90% confidence level. These upper limits lie below the cross section values needed to explain the BABAR form factor data.
Observation of the baryonic decayB¯0→Λc+p¯K−K+
We report the observation of the baryonic decay B^0 → Λ^+_c pK^−K^+ using a data sample of 471×10^6 BB pairs produced in e^+e^− annihilations at √s = 10.58 GeV. This data sample was recorded with the BABAR detector at the PEP-II storage ring at SLAC. We find B(B^0 → Λ^+_c pK^−K^+)=(2.5±0.4_((stat))±0.2_((syst))± 0.6_(B(Λ^+_c)))×10^(−5), where the uncertainties are statistical, systematic, and due to the uncertainty of the Λ^+_c →p K^−π^+ branching fraction, respectively. The result has a significance corresponding to 5.0 standard deviations, including all uncertainties. For the resonant decay B^0 → Λ^+_c pϕ, we determine the upper limit B(B^0 → Λ^+_c pϕ) <1.2 × 10^(−5) at 90% confidence le…
Study of radiative bottomonium transitions using converted photons
We use 111+/-1 million Upsilon(3S) and 89+/-1 million Upsilon(2S) events recorded by the BaBar detector at the PEP-II B-factory at SLAC to perform a study of radiative transitions between bottomonium states using photons that have been converted to e+e- pairs by the detector material. We observe Upsilon(3S) -> gamma chi_b0,2(1P) decay, make precise measurements of the branching fractions for chi_b1,2(1P,2P) -> gamma Upsilon(1S) and chi_b1,2(2P) -> gamma Upsilon(2S) decays, and search for radiative decay to the eta_b(1S) and eta_b(2S) states.
Measurement ofCPobservables inB±→DCPK±decays and constraints on the CKM angleγ
Using the entire sample of 467×10^6 Υ(4S)→BB[overbar] decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at the SLAC National Accelerator Laboratory, we perform an analysis of B^± → DK^± decays, using decay modes in which the neutral D meson decays to either CP-eigenstates or non-CP-eigenstates. We measure the partial decay rate charge asymmetries for CP-even and CP-odd D final states to be A_(CP+) = 0.25±0.06±0.02 and A_(CP-) = -0.09±0.07±0.02, respectively, where the first error is the statistical and the second is the systematic uncertainty. The parameter A_(CP+) is different from zero with a significance of 3.6 standard deviations, constituting evidence f…
Study of high-multiplicity three-prong and five-prong τ decays at BABAR
We present measurements of the branching fractions of three-prong and five-prong tau decay modes using a sample of 430 million tau lepton pairs, corresponding to an integrated luminosity of 468 fb(-1), collected with the BABAR detector at the PEP-II asymmetric-energy e_e storage rings at SLAC National Accelerator Laboratory. The tau(-) -> (3 pi)(-) eta nu(tau), tau(-) -> (3 pi)(-) omega nu(tau), and tau(-) f(1) (1285)nu(tau) branching fractions are presented, as well as a new limit on the branching fraction of the second-class current decay tau(-) -> pi(-) eta'(958)nu(tau). We search for the decay mode tau(-) -> K- eta'(958)nu(tau) and for five-prong decay modes with kaons, and place the fi…
Measurement of theI=1/2Kπ S-wave amplitude from Dalitz plot analyses ofηc→KK¯πin two-photon interactions
We study the processes γγ→K^0_SK^±π^∓ and γγ→K^+K^−π^0 using a data sample of 519 fb^(−1) recorded with the BABAR detector operating at the SLAC PEP-II asymmetric-energy e+e− collider at center-of-mass energies at and near the Υ(nS) (n=2, 3, 4) resonances. We observe ηc decays to both final states and perform Dalitz plot analyses using a model-independent partial wave analysis technique. This allows a model-independent measurement of the mass-dependence of the I=1/2 Kπ S-wave amplitude and phase. A comparison between the present measurement and those from previous experiments indicates similar behavior for the phase up to a mass of 1.5 GeV/c^2. In contrast, the amplitudes show very marked…
Search for lepton-number violatingB+→X−ℓ+ℓ′+decays
We report on a search for eleven lepton-number violating processes B^+→X^−l^+l'^+ with X^−=K^−, π^−, ρ^−, K^(*−), or D^− and l^+/l'^+=e^+ or μ^+, using a sample of 471±3 million BB events collected with the BABAR detector at the PEP-II e^+e^− collider at the SLAC National Accelerator Laboratory. We find no evidence for any of these modes and place 90% confidence level upper limits on their branching fractions in the range (1.5–26)×10_(−7).
Search for the decay modesD0→e+e−,D0→μ+μ−, andD0→e±μ∓
We present searches for the rare decay modes D^0→e^+e^-, D^0→μ^+μ^-, and D^0→e^±μ^∓ in continuum e^+e^-→cc events recorded by the BABAR detector in a data sample that corresponds to an integrated luminosity of 468 fb^(-1). These decays are highly Glashow–Iliopoulos–Maiani suppressed but may be enhanced in several extensions of the standard model. Our observed event yields are consistent with the expected backgrounds. An excess is seen in the D^0→μ^+μ^- channel, although the observed yield is consistent with an upward background fluctuation at the 5% level. Using the Feldman–Cousins method, we set the following 90% confidence level intervals on the branching fractions: B(D^0→e^+e^-)<1.7×10^…
Search forB-meson decays tob1ρandb1K*
We present a search for decays of B mesons to final states with a b(1) meson and a rho or K*(d892) meson. The search is based on a data sample consisting of 465 million B (B) over bar pairs collected by the BABAR detector at the SLAC National Accelerator Laboratory. We do not observe any statistically significant signal. The upper limits we set on the branching fractions range from 1.4 to 8.0 x 10(-6) at the 90% confidence level, including systematic uncertainties.
Search for Second-Class Currents inτ−→ωπ−ντ
We report an analysis of tau- decaying into omega.pi-.nu_tau with omega -> pi+pi-pi0 using a data sample containing nearly 320 million tau pairs collected with the BABAR detector at the PEP-II B-Factory. We find no evidence for second-class currents and we set an upper limit of 0.69% at 90% confidence level for the fraction of second-class currents in this decay mode.
Search forB+→D+K0andB+→D+K*0decays
We report a search for the rare decays B^+ → D^+K^0 and B^+ → D^+K^0 in an event sample of approximately 465 x 10^6 BB[overbar] pairs collected with the BABAR detector at the PEP-II asymmetric-energy e^+e^- collider at SLAC National Accelerator Laboratory. We find no significant evidence for either mode and we set 90% probability upper limits on the branching fractions of ℬ(B^+ → D^+K^0) < 2:9 x 10^(-6) and ℬ(B^+ → D^+K*^0) < 3:0 x 10^(-6).
Search for Low-Mass Dark-Sector Higgs Bosons
See paper for full list of authors - 7 pages, 5 postscript figures, submitted to Phys. Rev. Lett; Recent astrophysical and terrestrial experiments have motivated the proposal of a dark sector with GeV-scale gauge boson force carriers and new Higgs bosons. We present a search for a dark Higgs boson using 516 fb-1 of data collected with the BABAR detector. We do not observe a significant signal and we set 90% confidence level upper limits on the product of the Standard Model-dark sector mixing angle and the dark sector coupling constant.
Measurement of Collins asymmetries in inclusive production of charged pion pairs ine+e−annihilation atBABAR
We present measurements of Collins asymmetries in the inclusive process e^+e^−→ππX, where π stands for charged pions, at a center-of-mass energy of 10.6 GeV. We use a data sample of 468 fb^(−1) collected by the BABAR experiment at the PEP-II B factory at SLAC, and consider pairs of charged pions produced in opposite hemispheres of hadronic events. We observe clear asymmetries in the distributions of the azimuthal angles in two distinct reference frames. We study the dependence of the asymmetry on several kinematic variables, finding that it increases with increasing pion momentum and momentum transverse to the analysis axis, and with increasing angle between the thrust and beam axis.
Observation of Time-Reversal Violation in the B0 Meson System
Although CP violation in the B meson system has been well established by the B factories, there has been no direct observation of time reversal violation. The decays of entangled neutral B mesons into definite flavor states ($B^0$ or $\bar{B}^0$), and $J/\psi K_S^0$ or $c\bar{c} K_S^0$ final states (referred to as $B_+$ or $B_-$), allow comparisons between the probabilities of four pairs of T-conjugated transitions, for example, $\bar{B}^0 \rightarrow B_-$ and $B_- \rightarrow \bar{B}^0$, as a function of the time difference between the two B decays. Using 468 million $B\bar{B}$ pairs produced in $\Upsilon(4S)$ decays collected by the BABAR detector at SLAC, we measure T-violating parameter…
Study of thee+e−→K+K−reaction in the energy range from 2.6 to 8.0 GeV
The e^+e^− → K^+K^− cross section and charged-kaon electromagnetic form factor are measured in the e^+e^− center-of-mass energy range (E) from 2.6 to 8.0 GeV using the initial-state radiation technique with an undetected photon. The study is performed using 469 fb^(−1) of data collected with the BABAR detector at the PEP-II2 e^+e^− collider at center-of-mass energies near 10.6 GeV. The form factor is found to decrease with energy faster than 1/E^2 and approaches the asymptotic QCD prediction. Production of the K^+K^− final state through the J/ψ and ψ(2S) intermediate states is observed. The results for the kaon form factor are used together with data from other experiments to perform a mod…
Collins asymmetries in inclusive chargedKKandKπpairs produced ine+e−annihilation
We present measurements of Collins asymmetries in the inclusive process e^+e^− → h_1h_2X, h_1h_2 = KK, Kπ, ππ, at the center-of-mass energy of 10.6 GeV, using a data sample of 468 fb^(−1) collected by the BABAR experiment at the PEP-II B factory at SLAC National Accelerator Center. Considering hadrons in opposite thrust hemispheres of hadronic events, we observe clear azimuthal asymmetries in the ratio of unlike sign to like sign, and unlike sign to all charged h_1h_2 pairs, which increase with hadron energies. The Kπ asymmetries are similar to those measured for the ππ pairs, whereas those measured for high-energy KK pairs are, in general, larger.
Search forCPViolation inB0-B¯0Mixing Using Partial Reconstruction ofB0→D*−Xℓ+νℓand a Kaon Tag
We present results of a search for CP violation in B^0- B^0 mixing with the BABAR detector. We select a sample of B^0→D^(*-)Xl^+ν decays with a partial reconstruction method and use kaon tagging to assess the flavor of the other B meson in the event. We determine the CP violating asymmetry A_(CP)≡[N(B^0B^0)-N(B^0B^0)]/[N(B^0B^0)+N(B^0B^0)]=(0.06±0.17_(-0.32)^(+0.38))%, corresponding to Δ_(CP) = 1- |q/p|=(0.29±0.84_(-1.61)^(+1.88))×10^(-3).
Dalitz plot analyses ofB0→D−D0K+andB+→D¯0D0K+decays
We present Dalitz plot analyses for the decays of B mesons to D^−D^0K^+ and D^0D^0K^+. We report the observation of the D^∗_(s1)(2700)^+ resonance in these two channels and obtain measurements of the mass M(D^∗_(s1)(2700)+)=2699^(+14)_(−7) MeV/c^2 and of the width Γ(D^∗_(s1)(2700)+)=127^(+24)_(−19) MeV, including statistical and systematic uncertainties. In addition, we observe an enhancement in the D^0K^+ invariant mass around 2350–2500 MeV/c^2 in both decays B^0→D^−D^0K^+ and B^+→D^0D^0K^+, which we are not able to interpret. The results are based on 429 fb^(−1) of data containing 471×10^6BB pairs collected at the Υ(4S) resonance with the BABAR detector at the SLAC National Accelerato…
Extraction of form Factors from a Four-Dimensional Angular Analysis of B¯→D*ℓ−ν¯ℓ
An angular analysis of the decay B[over ¯]→D^{*}l^{-}ν[over ¯]_{l}, l∈{e,μ}, is reported using the full e^{+}e^{-} collision data set collected by the BABAR experiment at the ϒ(4S) resonance. One B meson from the ϒ(4S)→BB[over ¯] decay is fully reconstructed in a hadronic decay mode, which constrains the kinematics and provides a determination of the neutrino momentum vector. The kinematics of the semileptonic decay is described by the dilepton mass squared, q^{2}, and three angles. The first unbinned fit to the full four-dimensional decay rate in the standard model is performed in the so-called Boyd-Grinstein-Lebed approach, which employs a generic q^{2} parametrization of the underlying f…
Study of the decayB¯0→Λc+p¯π+π−and its intermediate states
We study the decay B^0→Λ_c^+p π^+π^-, reconstructing the Λ_c^+ baryon in the pK^-π^+ mode, using a data sample of 467×10^6 BB pairs collected with the BABAR detector at the PEP-II storage rings at SLAC. We measure branching fractions for decays with intermediate Σ_c baryons to be B[B^0→Σ_c(2455)^(++)pπ^-]=(21.3±1.0±1.0±5.5)×10^(-5), B[B^0→Σ_c(2520)^(++)pπ^-]=(11.5±1.0±0.5±3.0)×10^(-5), B[B^0→Σ_c(2455)^0pπ^+]=(9.1±0.7±0.4±2.4)×10^(-5), and B[B^0→Σ_c(2520)^0pπ^+]=(2.2±0.7±0.1±0.6)×10^(-5), where the uncertainties are statistical, systematic, and due to the uncertainty on the Λ_c^+→pK^-π^+ branching fraction, respectively. For decays without Σ_c(2455) or Σ_c(2520) resonances, we measure B[B^0→…
Measurements of theτmass and the mass difference of theτ+andτ−atBABAR
We present the result from a precision measurement of the mass of the tau lepton, M-tau, based on 423 fb(-1) of data recorded at the Upsilon(4S) resonance with the BABAR detector. Using a pseudomass endpoint method, we determine the mass to be 1776.68 +/- 0.12(stat)+/- 0.41(syst) MeV. We also measure the mass difference between the tau(+) and tau(-), and obtain (M-tau(+)-M-tau(-))/M-AVG(tau)=(-3.4 +/- 1.3(stat)+/- 0.3(syst))x10(-4), where M-AVG(tau) is the average value of M-tau(+) and M-tau(-).
Search for B+→K+τ+τ− at the BaBar Experiment
We search for the rare flavor-changing neutral current process B^{+}→K^{+}τ^{+}τ^{-} using data from the BABAR experiment. The data sample, collected at the center-of-mass energy of the ϒ(4S) resonance, corresponds to a total integrated luminosity of 424 fb^{-1} and to 471×10^{6} BB[over ¯] pairs. We reconstruct one B meson, produced in the ϒ(4S)→B^{+}B^{-} decay, in one of many hadronic decay modes and search for activity compatible with a B^{+}→K^{+}τ^{+}τ^{-} decay in the rest of the event. Each τ lepton is required to decay leptonically into an electron or muon and neutrinos. Comparing the expected number of background events with the data sample after applying the selection criteria,…
Measurement of the B0→D*−π+π−π+ branching fraction
Using a sample of (470.9 +- 2.8) x 10^6 BB-bar pairs, we measure the decay branching fraction B(B^0 -> D^*- pi^+ pi^- pi^+) = (7.26 +- 0.11 +- 0.31) x 10^-3, where the first uncertainty is statistical and the second is systematic. Our measurement will be helpful in studies of lepton universality by measuring B(B^0 -> D^*- tau^+ nu_tau) using tau^+ -> pi^+ pi^- pi^+ nu-bar_tau decays, normalized to B(B^0 -> D^*- pi^+ pi^- pi^+.
Study ofB±,0→J/ψK+K−K±,0and search forB0→J/ψϕatBaBar
We study the rare B meson decays B{+-,0} --> J/\psi\ K^+ K^- K{+-,0}, B{+-,0} --> J/\psi\ \phi\ K{+-,0}, and search for B0 --> J/\psi\ \phi, using 469 million BBbar events collected at the Upsilon(4S) resonance with the BABAR detector at the PEP-II e+e- asymmetric-energy collider. We present new measurements of branching fractions and a study of the J/\psi\phi mass distribution in search of new charmonium-like states. In addition, we search for the decay B0 --> J/\psi\ \phi, and find no evidence of a signal.
Evidence for the baryonic decayB¯0→D0ΛΛ¯
Evidence is presented for the baryonic $B$ meson decay $\bar{B}\rightarrow D^0 \Lambda \bar{\Lambda}$ based on a data sample of $471 \times 10^6$ $B\bar{B}$ pairs collected with the {\it BABAR} detector at the PEP2 asymmetric $e^+e^-$ collider located at the SLAC National Accelerator Laboratory. The branching fraction is determined to be $\mathcal{B}(\bar{B}\rightarrow D^0 \Lambda \bar{\Lambda}) = (9.8^{+2.9}_{-2.6} \pm 1.9)\times 10^{-6}$, corresponding to a significance of $3.4$ standard deviations including systematic uncertainties. A search for the related baryonic $B$ meson decay $\bar{B}\rightarrow D^0 \Sigma^0 \bar{\Lambda}$ with $\Sigma^0\rightarrow\Lambda\gamma$ is performed and an…
Measurement ofCPviolation observables and parameters for the decaysB±→DK*±
We study the decay B--> DK*- using a sample of 379x10(6) Upsilon(4S)-> BB events collected with the BABAR detector at the PEP-II B factory. We perform a Gronau-London-Wyler analysis where the D meson decays into either a CP-even (CP+) eigenstate (K+K-, pi(+)pi(-)), CP-odd (CP-) eigenstate (K-S(0)pi(0), K-S(0)phi, K-S(0)omega) or a non-CP state (K-pi(+)). We also analyze D meson decays into K+pi(-) from a Cabibbo-favored D-0 decay or doubly suppressed D-0 decay [Atwood-Dunietz-Soni (ADS) analysis]. We measure observables that are sensitive to the Cabibbo-Kobayashi-Maskawa angle gamma: the partial-rate charge asymmetries A(CP +/-), the ratios R-CP +/- of the B-decay branching fractions in CP …
Measurement of the mass of the D^{0} meson
We report a measurement of the D-0 meson mass using the decay chain D* (2010) + -> D-0 pi(+) with D-0 -> K-K-K+pi(+). The data were recorded with the BABAR detector at center-of-mass energies at and near the Upsilon(4S) resonance, and correspond to an integrated luminosity of approximately 477 fb(-1). We obtain m(D-0) (1864: 841 +/- 0: 048 +/- 0: 063) MeV, where the quoted errors are statistical and systematic, respectively. The uncertainty of this measurement is half that of the best previous measurement.
Observation of directCPviolation in the measurement of the Cabibbo-Kobayashi-Maskawa angleγwithB±→D(*)K(*)±decays
We report the determination of the Cabibbo-Kobayashi-Maskawa CP-violating angle γ through the combination of various measurements involving B^± → DK^±, B^± → D^*K^±, and B^± → DK^(*±) decays performed by the BABAR experiment at the PEP-II e^+e^- collider at SLAC National Accelerator Laboratory. Using up to 474 million BB pairs, we obtain γ=(69_(-16)^(+17))° modulo 180°. The total uncertainty is dominated by the statistical component, with the experimental and amplitude-model systematic uncertainties amounting to ±4°. The corresponding two-standard-deviation region is 41° < γ < 102°. This result is inconsistent with γ=0 with a significance of 5.9 standard deviations.
Measurements of Charged Current Lepton Universality and|Vus|Using Tau Lepton Decays toe−ν¯eντ,μ−ν¯μντ,π−ντ, andK−ντ
Using 467 fb(-1) of e+e- annihilation data collected with the BABAR detector, we measure (B(τ- → μ- ν(μ) ν(τ)))/(B(τ- → e- ν(e) ν(τ))) =(0.9796±0.0016±0.0036), (B(τ- → π- ν(τ)))/(B(τ- → e- ν(e) ν(τ))) = (0.5945±0.0014±0.0061), and (B(τ- → K- ν(τ)))/(B(τ- → e- ν(e) ν(τ))) = (0.03882±0.00032±0.00057), where the uncertainties are statistical and systematic, respectively. From these precision τ measurements, we test the standard model assumption of μ-e and τ-μ charge current lepton universality and provide determinations of |Vus| experimentally independent of the decay of a kaon.
Search for mixing-inducedCPviolation using partial reconstruction ofB¯0→D*+Xℓ−ν¯ℓand kaon tagging
This work is supported by the U.S. Department of Energy and National Science Foundation, the Natural Sciences and Engineering Research Council (Canada), the Commissariat a l’Energie Atomique and Institut National de Physique Nucleaire et de Physique des Particules (France), the Bundesministerium fur Bildung und Forschung and Deutsche Forschungsgemeinschaft (Germany), the Istituto Nazionale di Fisica Nucleare (Italy), the Foundation for Fundamental Research on Matter (The Netherlands), the Research Council of Norway, the Ministry of Education and Science of the Russian Federation, Ministerio de Economia y Competitividad (Spain), the Science and Technology Facilities Council (United Kingdom) …
Search for a Low-Mass Higgs Boson inΥ(3S)→γA0,A0→τ+τ−atBABAR
We search for a light Higgs boson, $A^0$, in the radiative decay $\Upsilon(3S)\to\gamma A^0$, $A^0\to\tau^+\tau^-$, $\tau^+\to e^+\nu_e \overline{\nu}_{\tau}$ or $\tau^+\to \mu^+ \nu_{\mu} \overline{\nu}_{\tau}$. The data sample contains 122 million $\Upsilon(3S)$ events recorded with the \babar detector. We find no evidence for a narrow structure in the studied $\tau^+\tau^-$ invariant mass region of $4.03(1.5-16)\times 10^{-5}$ across the $m_{\tau^+\tau^-}$ range. We also set a 90% C.L. upper limit on the $\tau^+\tau^-$-decay of the $\eta_b$ at ${\mathcal{B}}(\eta_b\to \tau^+\tau^-)<8%$.
Search for a light Higgs boson decaying to two gluons orss¯in the radiative decays ofΥ(1S)
We search for the decay Υ(1S)→γA^0, A^0→gg or ss , where A^0 is the pseudoscalar light Higgs boson predicted by the next-to-minimal supersymmetric Standard Model. We use a sample of (17.6±0.3)×10^6 Υ(1S) mesons produced in the BABAR experiment via e^+e^-→Υ(2S)→π^+π^-Υ(1S). We see no significant signal and set 90%-confidence-level upper limits on the product branching fraction B(Υ(1S)→γA^0)·B(A^0→gg or ss) ranging from 10^(-6) to 10^(-2) for A^0 masses in the range 0.5–9.0 GeV/c^2.
Search for a light Higgs resonance in radiative decays of theϒ(1S)with a charm tag
A search is presented for the decay Υ(1S)→ γA^0, A^0 → cc[bar], where A^0 is a candidate for the CP-odd Higgs boson of the next-to-minimal supersymmetric standard model. The search is based on data collected with the BABAR detector at the Υ(2S) resonance. A sample of Υ(1S) mesons is selected via the decay Υ(2S)→π + π − Υ(1S). The A^0 → cc[bar] decay is identified through the reconstruction of hadronic D^0, D^+, and D^∗ (2010)^+ meson decays. No significant signal is observed. The measured 90% confidence-level upper limits on the product branching fraction B(Υ(1S) → γA^0 ) × B(A^0 → cc[bar] ) range from 7.4×10^(−5) to 2.4×10^(−3) for A^0 masses from 4.00 to 8.95 GeV/c^2 and 9.10 to 9.25 Ge…
Search for Rare or Forbidden Decays of the D0 Meson
We present a search for nine lepton-number-violating and three lepton-flavor-violating neutral charm decays of the type D^{0}→h^{'-}h^{-}l^{'+}l^{+} and D^{0}→h^{'-}h^{+}l^{'±}l^{∓}, where h and h^{'} represent a K or π meson and l and l^{'} an electron or muon. The analysis is based on 468 fb^{-1} of e^{+}e^{-} annihilation data collected at or close to the ϒ(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory. No significant signal is observed for any of the twelve modes, and we establish 90% confidence level upper limits on the branching fractions in the range (1.0-30.6)×10^{-7}. The limits are between 1 and 3 orders of magnitude more stringent than previou…
Measurements of branching fractions andCPasymmetries and studies of angular distributions forB→ϕϕKdecays
We present branching fraction and CP asymmetry measurements as well as angular studies of B to phi phi K decays using 464 x 10^6 BBbar events collected by the BaBar experiment. The branching fractions are measured in the phi phi invariant mass range below the eta_c resonance (m_phiphi <2.85 GeV). We find B(B+ to phi phi K+) = (5.6 +/- 0.5 +/- 0.3) x 10^-6 and B(B0 to phi phi K0) = (4.5 +/- 0.8 +/- 0.3) x 10^-6, where the first uncertaintiy is statistical and the second systematic. The measured direct CP asymmetries for the B+- decays are A_CP = -0.10 +/- 0.08 +/- 0.02 below the eta_c threshold and A_CP = 0.09 +/- 0.10 +?- 0.02 in the eta_c resonance region (m_phiphi in [2.94,3.02] GeV). Ang…
Search forB+meson decay toa1+(1260)K*0(892)
We present a search for the decay B{sup +} --> {alpha}{sup +}{sub 1}(1260)K*{sup 0}(892). The data, collected with the BABAR detector at the SLAC National Accelerator Laboratory, represent 465 million B{anti B} pairs produced in e{sup +}e{sup -} annihilation at the energy of the {Upsilon}(4S). We find no significant signal and set an upper limit at 90% confidence level on the product of branching fractions B(B{sup +} --> {alpha}{sup +}{sub 1}(1260)K*{sup 0}(892)) x B({alpha}{sup +}{sub 1}(1260) --> {pi}{sup +}{pi}{sup -}{pi}{sup +}) of 1.8 x 10{sup -6}.
Dalitz plot analysis ofηc→K+K−ηandηc→K+K−π0in two-photon interactions
We study the processes γγ→K+K−η and γγ→K+K−π0 using a data sample of 519 fb−1 recorded with the BABAR detector operating at the SLAC PEP-II asymmetric-energy e+e− collider at center-of-mass energies at and near the Υ(nS) (n=2,3,4) resonances. We observe ηc→K+K−π0 and ηc→K+K−η decays, measure their relative branching fraction, and perform a Dalitz plot analysis for each decay. We observe the K∗0(1430)→Kη decay and measure its branching fraction relative to the Kπ decay mode to be R(K∗0(1430))=B(K∗0(1430)→Kη)B(K∗0(1430)→Kπ)=0.092±0.025+0.010−0.025. The ηc→K+K−η and K∗0(1430)→Kη results correspond to the first observations of these channels. The data also show evidence for ηc(2S)→K+K−π0 and f…
Measurements of directCPasymmetries inB→Xsγdecays using sum of exclusive decays
We measure the direct CP violation asymmetry, A_(CP), in B→X_sγ and the isospin difference of the asymmetry, ΔA_(CP), using 429 fb^(−1) of data collected at Υ(4S) resonance with the BABAR detector at the PEP-II asymmetric-energy e^+e^− storage rings operating at the SLAC National Accelerator Laboratory. B mesons are reconstructed from ten charged B final states and six neutral B final states. We find A_(CP)=+(1.7±1.9±1.0)%, which is in agreement with the Standard Model prediction and provides an improvement on the world average. Moreover, we report the first measurement of the difference between A_(CP) for charged and neutral decay modes, ΔA_(CP)=+(5.0±3.9±1.5)%. Using the value of ΔA_(CP)…
Search for the rare decayB→Kνν¯
We present a search for the rare decays B+→K+νν and B0→K0νν using 459×106 BB pairs collected with the BABAR detector at the SLAC National Accelerator Laboratory. Flavor-changing neutral-current decays such as these are forbidden at tree level but can occur through one-loop diagrams in the standard model (SM), with possible contributions from new physics at the same order. The presence of two neutrinos in the final state makes identification of signal events challenging, so reconstruction in the semileptonic decay channels B→D(*)lν of the B meson recoiling from the signal B is used to suppress backgrounds. We set an upper limit at the 90% confidence level (CL) of 1.3×10-5 on the total branch…
Observation of theχc2(2P)meson in the reactionγγ→DD¯atBABAR
A search for the Z(3930) resonance in gamma gamma production of the DDbar system has been performed using a data sample corresponding to an integrated luminosity of 384 fb^-1 recorded by the BABAR experiment at the PEP-II asymmetric-energy electron-positron collider. The DDbar invariant mass distribution shows clear evidence of the Z(3930) state with a significance of 5.8 sigma. We determine mass and width values of (3926.7 +- 2.7 +- 1.1) MeV/c^2 and (21.3 +- 6.8 +- 3.6) MeV, respectively. A decay angular analysis provides evidence that the Z(3930) is a tensor state with positive parity and C-parity (J^PC = 2^++); therefore we identify the Z(3930) state as the chi_c2(2P) meson. The value of…
Search for directCPviolation in singly Cabibbo-suppressedD±→K+K−π±decays
We report on a search for direct CP violation in the singly Cabibbo-suppressed decay D^+→K^+K^-π^+ using a data sample of 476 fb^(-1) of e^+e^- annihilation data accumulated with the BABAR detector at the SLAC PEP-II electron-positron collider, running at and just below the energy of the Υ(4S) resonance. The integrated CP-violating decay rate asymmetry A_(CP) is determined to be (0.37±0.30±0.15)%. Model-independent and model-dependent Dalitz plot analysis techniques are used to search for CP-violating asymmetries in the various intermediate states. We find no evidence for CP-violation asymmetry.
First Observation ofCPViolation inB¯0→DCP(*)h0Decays by a Combined Time-Dependent Analysis ofBABARand Belle Data
We report a measurement of the time-dependent CP asymmetry of B0->D(*)CP h0 decays, where the light neutral hadron h0 is a pi0, eta or omega meson, and the neutral D meson is reconstructed in the CP eigenstates K+ K-, K0S pi0 or K0S omega. The measurement is performed combining the final data samples collected at the Y(4S) resonance by the BaBar and Belle experiments at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain ( 471 +/- 3 ) x 10^6 BB pairs recorded by the BaBar detector and ( 772 +/- 11 ) x 10^6, BB pairs recorded by the Belle detector. We measure the CP asymmetry parameters -eta_f S = +0.66 +/- 0.10 (stat.) +/- 0.06 (syst.) an…
Measurement of thee+e−→pp¯cross section in the energy range from 3.0 to 6.5 GeV
The e^+e^−→pp cross section and the proton magnetic form factor have been measured in the center-of-mass energy range from 3.0 to 6.5 GeV using the initial-state radiation technique with an undetected photon. This is the first measurement of the form factor at energies higher than 4.5 GeV. The analysis is based on 469 fb^(−1) of integrated luminosity collected with the BABAR detector at the PEP-II collider at e+e− center-of-mass energies near 10.6 GeV. The branching fractions for the decays J/ψ→pp and ψ(2S)→pp have also been measured.
Search forCPviolation usingT-odd correlations inD+→K+KS0π+π−andDs+→K+KS0π+π−decays
We search for CP violation in a sample of 20,000 Cabibbo-suppressed decays, $D^+\rightarrow K^+K^0_S\pi^+\pi^-$, and 30,000 Cabibbo-favored decays, $D_s^+\rightarrow K^+K^0_S\pi^+\pi^-$. We use 520 $fb^{-1}$ of data recorded by the BaBar detector at the PEP-II asymmetric-energy $e^+e^-$ collider operating at center of mass energies near 10.6 $GeV$. We search for CP violation in the difference between the $T$-odd asymmetries obtained using triple product correlations of the $D^+$ ($D_s^+$) and $D^-$ ($D_s^-$) decays, respectively. The $T$ violation parameter values obtained are $\mathcal{A}_T(D^+) = (-12.0 \pm 10.0_{stat} \pm 4.6_{syst})\times 10^{-3}$ and $\mathcal{A}_T(D_s^+) = (-13.6 \pm …
Measurement of an excess ofB¯→D(*)τ−ν¯τdecays and implications for charged Higgs bosons
The concept for this analysis is to a large degree based on earlier BABAR work and we acknowledge the guidance provided by M. Mazur. The authors consulted with theorists A. Datta, S. Westhoff, S. Fajfer, J. Kamenik, and I. Nisandzic on the calculations of the charged Higgs contributions to the decay rates. We are grateful for the extraordinary contributions of our PEP-II colleagues in achieving the excellent luminosity and machine conditions that have made this work possible. The success of this project also relied critically on the expertise and dedication of the computing organizations that support BABAR. The collaborating institutions wish to thank SLAC for its support and the kind hospi…
Search for the rare decaysB→πℓ+ℓ−andB0→ηℓ+ℓ−
We present the results of a search for the rare flavor-changing neutral-current decays B → πl^+ l^- (π = π^±, π^0 and l = e, μ) and B^0 → ηl^+ l^- using a sample of e^+ e^- → Υ(4S) → BB decays corresponding to 428 fb^(-1) of integrated luminosity collected by the BABAR detector. No significant signal is observed, and we set an upper limit on the isospin and lepton-flavor averaged branching fraction of B(B → πl^+ l^-)<5.9 × 10^(-8) and a lepton-flavor averaged upper limit of B(B0 → ηl^+ l^-) < 6.4 × 10^(-8), both at the 90% confidence level. We also report 90% confidence level branching fraction upper limits for the individual modes B^+ → π^+ e^+ e^-, B^0 → π^0 e^+ e^-, B^+ → π^+ μ^+ μ^-, B…
Measurement ofB→K*(892)γBranching Fractions andCPand Isospin Asymmetries
We present an analysis of the decays B-0 -> K-*0(892)gamma and B+-> K*+(892)gamma using a sample of about 383x10(6) BB events collected with the BABAR detector at the PEP-II asymmetric energy B factory. We measure the branching fractions B(B-0 -> K-*0 gamma)=(4.47 +/- 0.10 +/- 0.16)x10(-5) and B(B+-> K*+gamma)=(4.22 +/- 0.14 +/- 0.16)x10(-5). We constrain the direct CP asymmetry to be -0.033 K-*gamma)< 0.028 and the isospin asymmetry to be 0.017 <Delta(0-)< 0.116, where the limits are determined by the 90% confidence interval and include both the statistical and systematic uncertainties.
Search for the decayB¯0→Λc+p¯pp¯
We report a search for the decay B^0 → Λ^+_cppp. Using a data sample of 471×10^6 BB pairs collected with the BABAR detector at the PEP-II2 storage ring at SLAC, we find no events and set an upper limit on the branching fraction B(B^0 → Λ^+_cppp)×^(B(Λ^+_c→pK^−π^+))_(0.050) <2.8×10^(−6) at 90% C.L., where we have normalized B(Λ^+_c → pK^−π^+) to the world average value.
Search forB→K(*)νν¯and invisible quarkonium decays
We search for the flavor-changing neutral-current decays B→K^(*)νν, and the invisible decays J/ψ→νν and ψ(2S)→νν via B→K^(*)J/ψ and B→K^(*)ψ(2S), respectively, using a data sample of 471×10^6 BB pairs collected by the BABAR experiment. We fully reconstruct the hadronic decay of one of the B mesons in the Υ(4S)→BB decay, and search for the B→K^(*)νν decay in the rest of the event. We observe no significant excess of signal decays over background and report branching fraction upper limits of B(B^+→K^+νν)<3.7×10^(-5), B(B^0→K^0νν)<8.1×10^(-5), B(B^+→K^(*+)νν)<11.6×10^(-5), B(B^0→K^(*0)νν)<9.3×10^(-5), and combined upper limits of B(B→Kνν)<3.2×10-5 and B(B→K^*νν)<7.9×10^(-5), all at the 90% con…
Production of charged pions, kaons, and protons ine+e−annihilations into hadrons ats=10.54 GeV
Inclusive production cross sections of π^±, K^± and p/p per hadronic e^+e^- annihilation event are measured at a center-of-mass energy of 10.54 GeV, using a relatively small sample of very high quality data from the BABAR experiment at the PEP-II B-factory at the SLAC National Accelerator Laboratory. The drift chamber and Cherenkov detector provide clean samples of identified π^±, K^±, and p/p over a wide range of momenta. Since the center-of-mass energy is below the threshold to produce a BB pair, with B a bottom-quark meson, these data represent a pure e^+e^-→qq sample with four quark flavors, and are used to test QCD predictions and hadronization models. Combined with measurements at oth…
Observation and polarization measurement ofB0→a1(1260)+a1(1260)−decay
We present measurements of the branching fraction B and longitudinal polarization fraction fL for B0→a1(1260)+a1(1260)- decays, with a1(1260)±→π-π+π±. The data sample, collected with the BABAR detector at the SLAC National Accelerator Laboratory, represents 465×106 produced BB pairs. We measure B(B0→a1(1260)+a1(1260)-)×[B(a1(1260)+→π-π+π+)]2= (11.8±2.6±1.6)×10-6 and fL=0.31±0.22±0.10, where the first uncertainty is statistical and the second systematic. The decay mode is measured with a significance of 5.0 standard deviations including systematic uncertainties.
Time-integrated luminosity recorded by the BABARdetector at the PEP-IIe+e- collider
We describe a measurement of the time-integrated luminosity of the data collected by the BABAR experiment at the PEP-II asymmetric-energy e^+e^- collider at the ϒ(4S), ϒ(3S), and ϒ(2S) resonances and in a continuum region below each resonance. We measure the time-integrated luminosity by counting e^+e^-→e^+e^- and (for the ϒ(4S) only) e^+e^-→μ^+μ^- candidate events, allowing additional photons in the final state. We use data-corrected simulation to determine the cross-sections and reconstruction efficiencies for these processes, as well as the major backgrounds. Due to the large cross-sections of e^+e^-→e^+e^- and e^+e^-→μ^+μ^-, the statistical uncertainties of the measurement are substanti…
Search for the decay modesB±→h±τℓ
We present a search for the lepton flavor violating decay modes B{sup {+-}} {yields} h{sup {+-}} {tau}{ell} (h = K, {pi}; {ell} = e, {mu}) using the BABAR data sample, which corresponds to 472 million B{bar B} pairs. The search uses events where one B meson is fully reconstructed in one of several hadronic final states. Using the momenta of the reconstructed B, h, and {ell} candidates, we are able to fully determine the {tau} four-momentum. The resulting {tau} candidate mass is our main discriminant against combinatorial background. We see no evidence for B{sup {+-}} {yields} h{sup {+-}} {tau}{ell} decays and set a 90% confidence level upper limit on each branching fraction at the level of …
Branching fraction measurements of the color-suppressed decaysB¯0toD(*)0π0,D(*)0η,D(*)0ω, andD(*)0η′and measurement of the polarization in the decayB¯0→D*0ω
We report updated branching fraction measurements of the color-suppressed decays B ^(0) → D^(0)π^(0), D^(*0)π^(0), D^(0)η, D^(*0)η, D^(0)ω, D^(*0)ω, D^(0)η′, and D^(*0)η′. We measure the branching fractions (×10^(-4)): B(B^0 → D^(0)π^(0)) = 2.69±0.09±0.13, B(B^(0) → D^(*0)π^(0)) = 3.05±0.14±0.28, B(B^(0) → D^(0)η) = 2.53±0.09±0.11, B(B^(0) → D^(*0)η) = 2.69±0.14±0.23, B(B^(0) → D^(0)ω) = 2.57±0.11±0.14, B(B^(0) → D^(*0)ω) = 4.55±0.24±0.39, B(B^(0)→D^(0)η′) = 1.48±0.13±0.07, and B(B^(0) → D^(*0)n′) = 1.49±0.22±0.15. We also present the first measurement of the longitudinal polarization fraction of the decay channel D*0ω, fL=(66.5±4.7±1.5)%. In the above, the first uncertainty is statistical …
Study ofX(3915)→J/ψωin two-photon collisions
We study the process $\gamma \gamma \to J/\psi \omega$ using a data sample of 519.2 $fb^{-1}$ recorded by the BaBar detector at SLAC at the PEP-II asymmetric-energy $e^+ e^-$ collider at center-of-mass energies near the $\Upsilon(nS)$ ($n = 2,3,4$) resonances. We confirm the existence of the charmonium-like resonance X(3915) decaying to $J/\psi \omega$ with a significance of 7.6 standard deviations, including systematic uncertainties, and measure its mass $(3919.4 \pm 2.2 \pm 1.6) MeV/c^2$ and width $(13 \pm 6 \pm 3) MeV$, where the first uncertainty is statistical and the second systematic. A spin-parity analysis supports the assignment $J^P=0^+$ and therefore the ident ification of the si…
Branching fraction and form-factor shape measurements of exclusive charmless semileptonicBdecays, and determination of|Vub|
We report the results of a study of the exclusive charmless semileptonic decays, B0→π-l+ν, B+→π0l+ν, B+→ωl+ν, B+→ηl+ν, and B+→η′l+ν (l=e or μ) undertaken with approximately 462×106 BB pairs collected at the Υ(4S) resonance with the BABAR detector. The analysis uses events in which the signal B decays are reconstructed with a loose neutrino reconstruction technique. We obtain partial branching fractions in several bins of q2, the square of the momentum transferred to the lepton-neutrino pair, for B0→π-l+ν, B+→π0l+ν, B+→ωl+ν, and B+→ηl+ν. From these distributions, we extract the form-factor shapes f+(q2) and the total branching fractions B(B0→π-l+ν)=(1.45±0.04stat±0.06syst)×10-4 (combined π- …
Study ofCPAsymmetry inB0−B¯0Mixing with Inclusive Dilepton Events
We present a measurement of the asymmetry A_{CP} between same-sign inclusive dilepton samples l^{+}l^{+} and l^{-}l^{-} (l=e, μ) from semileptonic B decays in ϒ(4S)→BB[over ¯] events, using the complete data set recorded by the BABAR experiment near the ϒ(4S) resonance, corresponding to 471×10^{6} BB[over ¯] pairs. The asymmetry A_{CP} allows comparison between the mixing probabilities P(B[over ¯]^{0}→B^{0}) and P(B^{0}→B[over ¯]^{0}), and therefore probes CP and T violation. The result, A_{CP}=[-3.9±3.5(stat)±1.9(syst)]×10^{-3}, is consistent with the standard model expectation.
Search for Invisible Decays of a Dark Photon Produced in e+e− Collisions at BaBar
We search for single-photon events in 53 fb^{-1} of e^{+}e^{-} collision data collected with the BABAR detector at the PEP-II B-Factory. We look for events with a single high-energy photon and a large missing momentum and energy, consistent with production of a spin-1 particle A^{'} through the process e^{+}e^{-}→γA^{'}; A^{'}→invisible. Such particles, referred to as "dark photons," are motivated by theories applying a U(1) gauge symmetry to dark matter. We find no evidence for such processes and set 90% confidence level upper limits on the coupling strength of A^{'} to e^{+}e^{-} in the mass range m_{A^{'}}≤8 GeV. In particular, our limits exclude the values of the A^{'} coupling sugges…
Observation ofB¯→D(*) π+π−ℓ−ν¯Decays ine+e−Collisions at theΥ(4S)Resonance
We report on measurements of the decays of B¯ mesons into the semileptonic final states B¯→D^(*)π^(+)π^(-)l^(-)ν¯, where D^(*) represents a D or D^(*) meson and l^(-) is an electron or a muon. These measurements are based on 471×10^(6) BB ¯ pairs recorded with the BABAR detector at the SLAC asymmetric B factory PEP-II. We determine the branching fraction ratios R_{π^{+}π^{-}}^{(*)}=B(B[over ¯]→D^{(*)}π^{+}π^{-}l^{-}ν[over ¯])/B(B[over ¯]→D^{(*)}l^{-}ν[over ¯]) using events in which the second B meson is fully reconstructed. We find R_{π^{+}π^{-}}=0.067±0.010±0.008 and R_{π^{+}π^{-}}^{*}=0.019±0.005±0.004, where the first uncertainty is statistical and the second is systematic. Based on thes…
Measurement of theγγ*→π0transition form factor
We study the reaction e+e- --> e+e-pi0 and measure the gamma gamma* --> pi0 transition form factor in the momentum transfer range from 4 to 40 GeV^2. The analysis is based on 442 fb^-1 of integrated luminosity collected at PEP-II with the BABAR detector at e+e- center-of-mass energies near 10.6 GeV.
Measurement of initial-state–final-state radiation interference in the processese+e−→μ+μ−γande+e−→π+π−γ
Charge asymmetry in processes e+ e- --> mu+ mu- gamma and e+ e- --> pi+ pi- gamma is measured using 232 fb-1 of data collected with the BABAR detector at center-of-mass energies near 10.58 GeV. An observable is introduced and shown to be very robust against detector asymmetries while keeping a large sensitivity to the physical charge asymmetry that results from the interference between initial and final state radiation. The asymmetry is determined as afunction of the invariant mass of the final-state tracks from production threshold to a few GeV/c2. It is compared to the expectation from QED for e+ e- --> mu+ mu- gamma and from theoretical models for e+ e- --> pi+ pi- gamma. A clear interfe…
Measurement of angular asymmetries in the decays B →K∗l+l-
This work is supported by the US Department of Energy and National Science Foundation, the Natural Sciences and Engineering Research Council (Canada), the Commissariat `a l’Energie Atomique and Institut National de Physique Nucl´eaire et de Physique des Particules (France), the Bundesministerium f¨ur Bildung und Forschung and Deutsche Forschungsgemeinschaft (Germany), the Istituto Nazionale di Fisica Nucleare (Italy), the Foundation for Fundamental Research on Matter (The Netherlands), the Research Council of Norway, the Ministry of Education and Science of the Russian Federation, Ministerio de Econom´ia y Competitividad (Spain), the Science and Technology Facilities Council (United Kingdom…
Measurement of theγγ*→ηandγγ*→η′transition form factors
We study the reactions e{sup +}e{sup -} {yields} e{sup +}e{sup -} {eta}{sup (/)} in the single-tag mode and measure the {gamma}{gamma}* {yields} {eta}{sup (/)} transition form factors in the momentum transfer range from 4 to 40 GeV{sup 2}. The analysis is based on 469 fb{sup -1} of integrated luminosity collected at PEP-II with the BABAR detector at e{sup +}e{sup -} center-of-mass energies near 10.6 GeV.
Precision Measurement of the Ratio B(ϒ(3S)→τ+τ−)/B(ϒ(3S)→μ+μ−)
We report on a precision measurement of the ratio ${\cal R}_{\tau\mu}^{\Upsilon(3S)} = {\cal B}(\Upsilon(3S)\to\tau^+\tau^-)/{\cal B}(\Upsilon(3S)\to\mu^+\mu^-)$ using data collected with the BaBar detector at the SLAC PEP-II $e^+e^-$ collider. The measurement is based on a 28 fb$^{-1}$ data sample collected at a center-of-mass energy of 10.355 GeV corresponding to a sample of 122 million $\Upsilon(3S)$ mesons. The ratio is measured to be ${\cal R}_{\tau\mu}^{\Upsilon(3S)} = 0.966 \pm 0.008_\mathrm{stat} \pm 0.014_\mathrm{syst}$ and is in agreement with the Standard Model prediction of 0.9948 within 2 standard deviations. The uncertainty in ${\cal R}_{\tau\mu}^{\Upsilon(3S)}$ is almost an o…
Observation of the Decay D0→K−π+e+e−
We report the observation of the rare charm decay D^{0}→K^{-}π^{+}e^{+}e^{-}, based on 468 fb^{-1} of e^{+}e^{-} annihilation data collected at or close to the center-of-mass energy of the ϒ(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory. We find the branching fraction in the invariant mass range 0.675<m(e^{+}e^{-})<0.875 GeV/c^{2} of the electron-positron pair to be B(D^{0}→K^{-}π^{+}e^{+}e^{-})=(4.0±0.5±0.2±0.1)×10^{-6}, where the first uncertainty is statistical, the second systematic, and the third due to the uncertainty in the branching fraction of the decay D^{0}→K^{-}π^{+}π^{+}π^{-} used as a normalization mode. The significance of the observation…