0000000000048389
AUTHOR
Ulrik Egede
showing 68 related works from this author
Measurement of theB0→K2*(1430)0γandB+→K2*(1430)+γbranching fractions
2004
We have investigated the exclusive, radiative B meson decays to K2*(1430) in 89* 10^6 BBbar events with the BaBar detector at the PEP-II storage ring. We measure the branching fractions BR(B0 -> K2*(1430)0 gamma) = (1.22 +-0.25 +-0.10)*10^(-5) and BR(B+ -> K2*(1430)+ gamma) = (1.45 +-0.40 +-0.15) * 10^(-5), where the first error is statistical and the second systematic. In addition, we measure the CP-violating asymmetry ACP(B0 -> K2*(1430)0 gamma) = -0.08 +- 0.15 +- 0.01.
First observation of a baryonic Bc+ decay
2014
A baryonic decay of the $B_c^+$ meson, $B_c^+\to J/\psi p\overline{p}\pi^+$, is observed for the first time, with a significance of $7.3$ standard deviations, in $pp$ collision data collected with the LHCb detector and corresponding to an integrated luminosity of $3.0$ fb$^{-1}$ taken at center-of-mass energies of $7$ and $8$ $\mathrm{TeV}$. With the $B_c^+\to J/\psi \pi^+$ decay as normalization channel, the ratio of branching fractions is measured to be \begin{equation*} \frac{\mathcal{B}(B_c^+\to J/\psi p\overline{p}\pi^+)}{\mathcal{B}(B_c^+\to J/\psi \pi^+)} = 0.143^{\,+\,0.039}_{\,-\,0.034}\,(\mathrm{stat})\pm0.013\,(\mathrm{syst}). \end{equation*} The mass of the $B_c^+$ meson is dete…
Measurements of the Mass and Width of theηcMeson and of anηc(2S)Candidate
2004
The mass m(eta(c)) and total width Gamma(eta(c))(tot) of the eta(c) meson have been measured in two-photon interactions at the SLAC e(+)e(-) asymmetric B Factory with the BABAR detector. With a sample of approximately 2500 reconstructed eta(c)-->K(0)(S)K+/-pi(-/+) decays in 88 fb(-1) of data, the results are m(eta(c))=2982.5+/-1.1(stat)+/-0.9(syst) MeV/c(2) and Gamma(eta(c))(tot)=34.3+/-2.3(stat)+/-0.9(syst) MeV/c(2). Using the same decay mode, a second resonance with 112+/-24 events is observed with a mass of 3630.8+/-3.4(stat)+/-1.0(syst) MeV/c(2) and width of 17.0+/-8.3(stat)+/-2.5(syst) MeV/c(2). This observation is consistent with expectations for the eta(c)(2S) state.
Search for theX(4140)state inB+→J/ψϕK+decays
2012
We investigate the decay B+ -> J/psi phi K+ in a search for the X(4140) state, a narrow threshold resonance in the J/psi phi system. The data sample corresponds to an integrated luminosity of 10.4 fb(-1) of p (p) over bar collisions at root s = 1.96 TeV collected by the D0 experiment at the Fermilab Tevatron collider. We observe a mass peak with a statistical significance of 3.1 standard deviations and measure its invariant mass to be M = 4159.0 +/- 4.3(stat) +/- 6.6(syst) MeV and its width to be Gamma = 19.9 +/- 12.6(stat)(-8.0)(+3.0)(syst) MeV.
Observations of Bs0→ψ(2S)η and B(s)0→ψ(2S)π+π− decays
2013
First observations of the $B^0_s \rightarrow \psi(2S) \eta$, $B^0 \rightarrow \psi(2S) \pi^+ \pi^-$ and $B^0_s \rightarrow \psi(2S) \pi^+ \pi^-$ decays are made using a dataset corresponding to an integrated luminosity of 1.0~$fb^{-1}$ collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=7$ TeV. The ratios of the branching fractions of each of the $\psi(2S)$ modes with respect to the corresponding $J/\psi$ decays are \[ \frac{\mathcal{B}(B^0_s \rightarrow \psi(2S) \eta) }{\mathcal{B}(B^0_s \rightarrow J/\psi \eta)} =0.83\pm0.14\,(stat)\pm0.12\,(syst)\pm0.02\,(\mathcalB}), \] \[ \frac{\mathcal{B}(B^0 \rightarrow \psi(2S) \pi^+ \pi^-)}{\mathcal{…
Model-Independent Evidence forJ/ψpContributions toΛb0→J/ψpK−Decays
2016
The data sample of Lambda(0)(b) -> J/psi pK(-) decays acquired with the LHCb detector from 7 and 8 TeV pp collisions, corresponding to an integrated luminosity of 3 fb(-1), is inspected for the presence of J/psi p or J/psi K- contributions with minimal assumptions about K(-)p contributions. It is demonstrated at more than nine standard deviations that Lambda(0)(b) -> J/psi pK(-) decays cannot be described with K- p contributions alone, and that J/psi K- contributions play a dominant role in this incompatibility. These model-independent results support the previously obtained model-dependent evidence for P-c(+)-> J/psi p charmonium-pentaquark states in the same data sample.
Symmetries in the angular distribution of exclusive semileptonic B decays
2010
We discuss a method to construct observables protected against QCD uncertainties based on the angular distribution of the exclusive Bd -> K(*0}(-> Kpi) l+ l- decay. We focus on the identification and the interpretation of all the symmetries of the distribution. They constitute a key ingredient to construct a set of so-called transverse observables. We work in the framework of QCD factorization at NLO supplemented by an estimate of power-suppressed Lambda/mb corrections. A discussion of the new physics properties of two of the transverse asymmetries, AT^{(2)} and AT^{(5)}, is presented. A comparison between the transverse asymmetry AT^{(2)} and the forward-backward asymmetry shows that…
Search for Strange-Pentaquark Production ine+e−Annihilation ats=10.58 GeV
2005
We search for strange-pentaquark states that have been previously reported by other experiments--the Theta (1540)(+), Xi(5)(1860)(--), and Xi(5)(1860)(0)--in 123 fb(-1) of data recorded with the BABAR detector at the PEP-II e(+)e(-) storage ring. We find no evidence for these states and set 95% confidence level upper limits on the number of Theta(1540)(+) and Xi(5)(1860)(--) pentaquarks produced per e(+)e(-) annihilation into qq and Gamma(4S) decay. For qq events the Theta(1540)(+) [Xi(5)(1860)(--)] limit is about 8 [4] times lower than the rates measured for ordinary baryons of similar mass.
Measurement of the resonant andCPcomponents inB¯0→J/ψπ+π−decays
2014
The resonant structure of the reaction (B) over bar (0) --> J/psi pi(+)pi(-) is studied using data from 3 fb(-1) of integrated luminosity collected by the LHCb experiment, one third at 7 TeV center-of-mass energy and the remainder at 8 TeV. The invariant mass of the pi(+)pi(-) pair and three decay angular distributions are used to determine the fractions of the resonant and nonresonant components. Six interfering pi(+)pi(-) states, rho(770), f(0)(500), f(2)(1270), rho(1450), omega(782) and rho(1700), are required to give a good description of invariant mass spectra and decay angular distributions. The positive and negative charge parity fractions of each of the resonant final states are det…
Search for Hidden-Sector Bosons inB0→K*0μ+μ−Decays
2015
A search is presented for hidden-sector bosons, $\chi$, produced in the decay ${B^0\!\to K^*(892)^0\chi}$, with $K^*(892)^0\!\to K^{+}\pi^{-}$ and $\chi\!\to\mu^+\mu^-$. The search is performed using $pp$-collision data corresponding to 3.0 fb$^{-1}$ collected with the LHCb detector. No significant signal is observed in the accessible mass range $214 \leq m({\chi}) \leq 4350$ MeV, and upper limits are placed on the branching fraction product $\mathcal{B}(B^0\!\to K^*(892)^0\chi)\times\mathcal{B}(\chi\!\to\mu^+\mu^-)$ as a function of the mass and lifetime of the $\chi$ boson. These limits are of the order of $10^{-9}$ for $\chi$ lifetimes less than 100 ps over most of the $m(\chi)$ range, a…
Study of Beauty Hadron Decays into Pairs of Charm Hadrons
2014
First observations of the decays Λ[0 over b] → Λ[+ over c]D[− over (s)] are reported using data corresponding to an integrated luminosity of 3 fb[superscript −1] collected at 7 and 8 TeV center-of-mass energies in proton-proton collisions with the LHCb detector. In addition, the most precise measurement of the branching fraction B(B[0 over s] → D[superscript +]D[− over s]) is made and a search is performed for the decays B[0 over (s)] → Λ[+ over c]Λ[− over c]. The results obtained are B(Λ[0 over b] → Λ[+ over c]D[superscript −])/B(Λ[0 over b] → Λ[+ over c]D[− over s]) = 0.042 ± 0.003(stat) ± 0.003(syst), ⎡⎣B(Λ[0 over b] → Λ[+ over c]D[− over s]) over B([¯ over B[superscript 0] → D[superscr…
Measurements of Branching Fractions andCP-Violating Asymmetries inBMeson Decays to Charmless Two-Body States Containing aK0
2003
We present measurements of branching fractions and \CP-violating asymmetries in decays of $B$ mesons to two-body final states containing a \Kz. The results are based on a data sample of approximately 88 million \upsbb decays collected with the \babar detector at the \pep2 asymmetric-energy $B$ Factory at SLAC. We measure $\BR(\Bp\to\Kz\pip) = (22.3 \pm 1.7 \pm 1.1)\times 10^{-6}$, $\BR(\Bz\to\Kz\piz) = (11.4\pm 1.7\pm 0.8)\times 10^{-6}$, $\BR(\Bp\to\Kzb\Kp) < 2.5\times 10^{-6}$, and $\BR(\Bz\to\KzKzb) < 1.8\times 10^{-6}$, where the first uncertainty is statistical and the second is systematic, and the upper limits are at the 90% confidence level. In addition, the following \CP-violating a…
Flavor physics in the quark sector
2010
218 páginas, 106 figuras, 89 tablas.-- arXiv:0907.5386v2.-- Report of the CKM workshop, Rome 9-13th Sep. 2008.-- et al.
Observation of the DecayB→J/ψηKand Search forX(3872)→J/ψη
2004
We report the observation of the B meson decay B±→J/ψηK± and evidence for the decay B0→J/ψηKS0, using 90×106 BB events collected at the Υ(4S) resonance with the BABAR detector at the SLAC PEP-II e+e- asymmetric-energy storage ring. We obtain branching fractions of B(B±→J/ψηK±)=[10.8±2.3(stat)±2.4(syst)]×10-5 and B(B0→J/ψηKS0)=[8.4±2.6(stat)±2.7(syst)]×10-5. We search for the new narrow mass state, the X(3872), recently reported by the Belle Collaboration, in the decay B±→X(3872)K±,X(3872)→J/ψη and determine an upper limit of B[B±→X(3872)K±→J/ψηK±]<7.7×10-6 at 90% confidence level.
Measurement of double charmonium production ine+e−annihilations ats=10.6 GeV
2005
We study $e^+e^-\to J/\psi c\bar{c}$ by measuring the invariant mass distribution recoiling against fully reconstructed $J/\psi$ decays, using 124 fb$^{-1}$ of data collected with a center-of-mass energy of 10.6 GeV with the $BaBar$ detector. We observe signals for $\eta_c(1S)$, $\chi_{c0}$, and $\eta_c(2S)$ in the recoil mass distribution, thus confirming previous measurements. We measure $\sigma(e^+e^-\to J/\psi+c\bar{c}) {\cal B} (c\bar{c} \to >2 charged)$ to be $17.6\pm2.8 (stat)^{+1.5}_{-2.1}(syst)$ fb, $ 10.3\pm2.5(stat)^{+1.4}_{-1.8}syst)$ fb, and $16.4\pm3.7(stat)^{+2.4}_{-3.0}(syst)$ fb with $c\bar{c}=\eta_c(1S)$, $\chi_{c0}$, and $\eta_c(2S)$, respectively.
Measurement of the branching fractions for inclusiveB−andB¯0decays to flavor-taggedD,Ds, andΛc
2004
We report on the inclusive branching fractions of $B^-$ and of ${\bar B}^0$ mesons decaying to ${D^0 X}$, ${{\bar D}^0 X}$, ${D^+ X}$, ${D^- X}$, ${D_s^+ X}$, ${D_s^- X}$, ${\Lambda_c^+ X}$, ${{\bar \Lambda}_c^- X}$, based on a sample of 88.9 million $B \bar B$ events recorded with the $BABAR$ detector at the $\Upsilon(4S)$ resonance. Events are selected by completely reconstructing one $B$ and searching for a reconstructed charmed particle in the rest of the event. We measure the number of charmed and of anti-charmed particles per $B$ decay and derive the total charm yield per $B^-$ decay, $n_c^- = 1.313 \pm 0.037 \pm 0.062 ^{+0.063}_{-0.042} $, and per ${\bar B}^0$ decay, $n_c^0 = 1.276 \…
Precision luminosity measurements at LHCb
2014
Measuring cross-sections at the LHC requires the luminosity to be determined accurately at each centre-of-mass energy $\sqrt{s}$. In this paper results are reported from the luminosity calibrations carried out at the LHC interaction point 8 with the LHCb detector for $\sqrt{s}$ = 2.76, 7 and 8 TeV (proton-proton collisions) and for $\sqrt{s_{NN}}$ = 5 TeV (proton-lead collisions). Both the "van der Meer scan" and "beam-gas imaging" luminosity calibration methods were employed. It is observed that the beam density profile cannot always be described by a function that is factorizable in the two transverse coordinates. The introduction of a two-dimensional description of the beams improves sig…
First observation of the rareB+→D+K+π−decay
2016
The B+→D+K+π- decay is observed in a data sample corresponding to 3.0 fb-1 of pp collision data recorded by the LHCb experiment during 2011 and 2012. The signal significance is 8σ and the branching fraction is measured to be B(B+→D+K+π-)=(5.31±0.90±0.48±0.35)×10-6, where the uncertainties are statistical, systematic and due to the normalization mode B+→D-K+π+, respectively. The Dalitz plot appears to be dominated by broad structures. Angular distributions are exploited to search for quasi-two-body contributions from B+→D2∗(2460)0K+ and B+→D+K∗(892)0 decays. No significant signals are observed and upper limits are set on their branching fractions.
Dalitz plot analysis ofBs0→D¯0K−π+decays
2014
The resonant substructure of B-s(0) -> (D) over bar K-0(-)pi(+) decays is studied with the Dalitz plot analysis technique. The study is based on a data sample corresponding to an integrated luminosity of 3.0 fb(-1) of pp collision data recorded by LHCb. A structure at m((D) over bar K-0(-)) approximate to 2.86 GeV/c(2) is found to be an admixture of spin-1 and spin-3 resonances. The masses and widths of these states and of the D-s2*(2573)(-) meson are measured, as are the complex amplitudes and fit fractions for all the (D) over bar K-0(-) and K-pi(-) components included in the amplitude model. In addition, the D-s2*(2573)(-) resonance is confirmed to be spin 2.
Search forB-meson decays to two-body final states witha0(980) mesons
2004
We present a search for B decays to charmless final states involving charged or neutral a0 mesons. The data sample corresponds to 89 million BBbar pairs collected with the BABAR detector operating at the PEP-II asymmetric-energy B Factory at SLAC. We find no significant signals and determine the following 90% C.L. upper limits: BR(B0 -> a0-pi+) a0-K+) a0-K0bar) a00pi+) a00K+) a00K0) a0X and a0 -> etapi, where X indicates K or pi.
Measurement of theB→Xsℓ+ℓ−Branching Fraction with a Sum over Exclusive Modes
2004
We present a preliminary measurement of time-dependent We measure the branching fraction for the flavor-changing neutral-current process B -> Xs l+ l- with a sample of 89 x 10^6 Upsilon(4S) -> BBbar events recorded with the BaBar detector at the PEP-II e+e- storage ring. The final state is reconstructed from e+e- or mu+mu- pairs and a hadronic system consisting of one K or K0s and up to two pions, with at most one pi0. We observe a signal of 40 +/- 10(stat) +/- 2(syst) events and extract the inclusive branching fraction B(B -> Xs l+ l-) = (5.6 +/- 1.5(stat) +/- 0.6(exp syst) +/- 1.1(model syst)) x 10^-6 for mll > 0.2 GeV/c^2.
Towards the european strategy for particle physics: The briefing book
2007
This document was prepared as part of the briefing material for the Workshop of the CERN Council Strategy Group, held in DESY Zeuthen from 2nd to 6th May 2006. It gives an overview of the physics issues and of the technological challenges that will shape the future of the field, and incorporates material presented and discussed during the Symposium on the European Strategy for Particle Physics, held in Orsay from 30th January to 2nd February 2006, reflecting the various opinions of the European community as recorded in written submissions to the Strategy Group and in the discussions at the Symposium.
First experimental study of photon polarization in radiative B0s decays.
2017
The polarization of photons produced in radiative $B^{0}_{s}$ decays is studied for the first time. The data are recorded by the LHCb experiment in $pp$ collisions corresponding to an integrated luminosity of 3fb$^{-1}$ at center-of-mass energies of $7$ and $8$TeV. A time-dependent analysis of the $B^{0}_{s} \to \phi \gamma$ decay rate is conducted to determine the parameter ${\mathcal{A}}^\Delta$, which is related to the ratio of right- over left-handed photon polarization amplitudes in $b \to s \gamma$ transitions. A value of ${\mathcal{A}}^\Delta=-0.98^{\,+0.46\,+0.23}_{\,-0.52\,-0.20}$ is measured. This result is consistent with the Standard Model prediction within two standard deviatio…
Measurement ofCPviolation parameters inB0→DK*0decays
2014
An analysis of B0→DK*0 decays is presented, where D represents an admixture of D0 and D¯0 mesons reconstructed in four separate final states: K−π+, π−K+, K+K− and π+π−. The data sample corresponds to 3.0 fb−1 of proton-proton collision, collected by the LHCb experiment. Measurements of several observables are performed, including CP asymmetries. The most precise determination is presented of rB(DK*0), the magnitude of the ratio of the amplitudes of the decay B0→DK+π− with a b→u or a b→c transition, in a Kπ mass region of ±50 MeV/c2 around the K∗(892) mass and for an absolute value of the cosine of the K*0 helicity angle larger than 0.4.
Measurement of Branching Fractions and Charge Asymmetries inB±→ρ±π0andB±→ρ0π±Decays, and Search forB0→ρ0π0
2004
We present measurements of branching fractions and charge asymmetries in $B$-meson decays to ${\ensuremath{\rho}}^{+}{\ensuremath{\pi}}^{0}$, ${\ensuremath{\rho}}^{0}{\ensuremath{\pi}}^{+}$, and ${\ensuremath{\rho}}^{0}{\ensuremath{\pi}}^{0}$. The data sample comprises $89\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $\ensuremath{\Upsilon}(4S)\ensuremath{\rightarrow}B\overline{B}$ decays collected with the BABAR detector at the PEP-II asymmetric-energy $B$ Factory at SLAC. We find the charge-averaged branching fractions $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{+}{\ensuremath{\pi}}^{0})=[10.9\ifmmode\pm\else\textpm\fi{}1.9\mathrm{(}\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{…
Evidence for Exotic Hadron Contributions toΛb0→J/ψpπ−Decays
2016
A full amplitude analysis of $\Lambda_b^0 \to J/\psi p \pi^-$ decays is performed with a data sample acquired with the LHCb detector from 7 and 8 TeV $pp$ collisions, corresponding to an integrated luminosity of 3 fb$^{-1}$. A significantly better description of the data is achieved when, in addition to the previously observed nucleon excitations $N\to p\pi^-$, either the $P_c(4380)^+$ and $P_c(4450)^+\to J/\psi p$ states, previously observed in $\Lambda_b^0 \to J/\psi p K^-$ decays, or the $Z_c(4200)^-\to J/\psi \pi^-$ state, previously reported in $B^0 \to J/\psi K^+ \pi^-$ decays, or all three, are included in the amplitude models. The data support a model containing all three exotic sta…
Observation ofJ/ψpResonances Consistent with Pentaquark States inΛb0→J/ψK−pDecays
2015
Observations of exotic structures in the J/ψp channel, that we refer to as pentaquark-charmonium states, in Λ0b→J/ψK−p decays are presented. The data sample corresponds to an integrated luminosity of 3/fb acquired with the LHCb detector from 7 and 8 TeV pp collisions. An amplitude analysis is performed on the three-body final-state that reproduces the two-body mass and angular distributions. To obtain a satisfactory fit of the structures seen in the J/ψp mass spectrum, it is necessary to include two Breit-Wigner amplitudes that each describe a resonant state. The significance of each of these resonances is more than 9 standard deviations. One has a mass of 4380±8±29 MeV and a width of 205±1…
Effective lifetime measurements in theBs0→K+K−,B0→K+π−andBs0→π+K−decays
2014
Measurements of the effective lifetimes in the B-s(0) -> K+K-, B-0 -> K+pi(-) and B-s(0) -> pi K-+(-) decays are presented using 1.0 fb(-1)of pp collision data collected at a centre-of-mass energy of 7 TeV by the LHCb experiment. The analysis uses a data-driven approach to correct for the decay time acceptance. The measured effective lifetimes are tau(Bs0 -> K+K-) = 1.407 +/- 0.016 (stat) +/- 0.007 (syst) ps, tau(Bs0 -> K+pi-) = 1.524 +/- 0.011 (stat) +/- 0.004 (syst) ps, tau(Bs0 ->pi+K-) = 1.60 +/- 0.06 (stat) +/- 0.01 (syst) ps. This is the most precise determination to date of the effective lifetime in the B-s(0) -> K+K- decay and provides constraints on contributions from physics beyond…
Studies of the resonance structure inD0→KS0K±π∓decays
2016
Amplitude models are constructed to describe the resonance structure of D0→ K-π+π+π- and D0→ K+π-π-π+ decays using pp collision data collected at centre-of-mass energies of 7 and 8 TeV with the LHCb experiment, corresponding to an integrated luminosity of 3.0 fb- 1. The largest contributions to both decay amplitudes are found to come from axial resonances, with decay modes D0→ a1(1260) +K- and D0→ K1(1270 / 1400) +π- being prominent in D0→ K-π+π+π- and D0→ K+π-π-π+, respectively. Precise measurements of the lineshape parameters and couplings of the a1(1260) +, K1(1270) - and K(1460) - resonances are made, and a quasi model-independent study of the K(1460) - resonance is performed. The coher…
Measurement of Branching Fractions and Charge Asymmetries inBDecays to anηMeson and aK*Meson
2006
We present measurements of branching fractions and charge asymmetries for the decays B-->etaK*, where K* indicates a spin 0, 1, or 2 Kpi system. The data sample corresponds to 344x10(6) BB pairs collected with the BABAR detector at the PEP-II asymmetric-energy e+ e- collider at SLAC. We measure the branching fractions (in units of 10(-6): B(B0-->etaK*0(892))=16.5+/-1.1+/-0.8, B(B+-->etaK*+(892))=18.9+/-1.8+/-1.3, B(B0-->eta(Kpi)0*0)=11.0+/-1.6+/-1.5, B(B+-->eta(Kpi)0*+)=18.2+/-2.6+/-2.6, B(B0-->etaK2*0(1430))=9.6+/-1.8+/-1.1, and B(B+-->etaK2*+(1430))=9.1+/-2.7+/-1.4. We also determine the charge asymmetries for all decay modes.
The decay
2010
In this paper the potential for the discovery of new physics in the exclusive decay B ¯ d → K ¯ ⁎ 0 μ + μ − is discussed. Attention is paid to constructing observables which are protected from uncertainties in QCD form factors and at the same time observe the symmetries of the angular distribution. We discuss the sensitivity to new physics in the observables including the effect of CP-violating phases.
Measurement of the Ratio of Branching FractionsB(B¯0→D*+τ−ν¯τ)/B(B¯0→D*+μ−ν¯μ)
2015
The branching fraction ratio R(D-*) = B((B) over bar (0) -> D-*(+)tau(-)(nu) over bar (tau))/B((B) over bar (0) -> D-*(+)mu(-)(nu) over bar (mu)) is measured using a sample of proton-proton collision data corresponding to 3.0 fb(-1) of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode tau(-) -> mu(-)(nu) over bar (mu)nu(tau). The semitauonic decay is sensitive to contributions from non-standard-model particles that preferentially couple to the third generation of fermions, in particular, Higgs-like charged scalars. A multidimensional fit to kinematic distributions of the candidate (B) over bar (0) decays gives R(D-*) =…
Search for weakly decaying b -flavored pentaquarks
2018
Investigations of the existence of pentaquark states containing a single $b$ (anti)quark decaying weakly into four specific final states J/$\psi K^+\pi^- p$, J/$\psi K^- \pi^- p$, J/$\psi K^- \pi^+ p$, and $J/\psi \phi (1020) p$ are reported. The data sample corresponds to an integrated luminosity of 3.0/fb in 7 and 8 TeV pp collisions acquired with the LHCb detector. Signals are not observed and upper limits are set on the product of the production cross section times branching fraction with respect to that of the $\Lambda_b$.
Model-independent confirmation of theZ(4430)−state
2015
The decay $B^0\to \psi(2S) K^+\pi^-$ is analyzed using $\rm 3~fb^{-1}$ of $pp$ collision data collected with the LHCb detector. A model-independent description of the $\psi(2S) \pi$ mass spectrum is obtained, using as input the $K\pi$ mass spectrum and angular distribution derived directly from data, without requiring a theoretical description of resonance shapes or their interference. The hypothesis that the $\psi(2S)\pi$ mass spectrum can be described in terms of $K\pi$ reflections alone is rejected with more than 8$\sigma$ significance. This provides confirmation, in a model-independent way, of the need for an additional resonant component in the mass region of the $Z(4430)^-$ exotic sta…
Observation ofe+e−Annihilation into theC=+1Hadronic Final Statesρ0ρ0andϕρ0
2006
The authors report the first observation of e{sup +}e{sup -} annihilations into states of positive C-parity, namely {rho}{sup 0}{rho}{sup 0} and {phi}{rho}{sup 0}. The two states are observed in the {pi}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -} and K{sup +}K{sup -} {pi}{sup +}{pi}{sup -} final states, respectively, in a data sample of 225 fb{sup -1} collected by the BABAR experiment at the PEP-II e{sup +}e{sup -} storage rings at energies near {radical}s = 10.58 GeV. The distributions of cos {theta}*, where {theta}* is the center-of-mass polar angle of the {phi} meson or the forward {rho}{sup 0} meson, suggest production by two-virtual-photon annihilation. They measure cross sections within …
Dalitz plot analysis ofB0→D¯0π+π−decays
2015
The resonant substructures of $B^0 \to \overline{D}^0 \pi^+\pi^-$ decays are studied with the Dalitz plot technique. In this study a data sample corresponding to an integrated luminosity of 3.0 fb$^{-1}$ of $pp$ collisions collected by the LHCb detector is used. The branching fraction of the $B^0 \to \overline{D}^0 \pi^+\pi^-$ decay in the region $m(\overline{D}^0\pi^{\pm})>2.1$ GeV$/c^2$ is measured to be $(8.46 \pm 0.14 \pm 0.29 \pm 0.40) \times 10^{-4}$, where the first uncertainty is statistical, the second is systematic and the last arises from the normalisation channel $B^0 \to D^*(2010)^-\pi^+$. The $\pi^+\pi^-$ S-wave components are modelled with the Isobar and K-matrix formalisms. …
Measurement of branching fractions and charge asymmetries for exclusive B decays to charmonium
2005
We report measurements of branching fractions and charge asymmetries of exclusive decays of neutral and charged B mesons into two-body final states containing a charmonium state and a light strange meson. The charmonium mesons considered are J/Psi, Psi(2S) and Chi_c1, and the light meson is either K or K*. We use a sample of about 124 million BBbar events collected with the BABAR detector at the PEP-II storage ring at the Stanford Linear Accelerator Center.
Search for the rare decaysB+→D(*)+KS0
2005
The authors report on the search for the rare decays B{sup +} {yields} D{sup (*)+} K{sub s}{sup 0} in approximately 226 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEp-II asymmetric-energy B factory at SLAC. They do not observe any significant signal and they set 90% confidence level upper limits on the branching fractions, {Beta}(B{sup +} {yields} D{sup +}K{sup 0}) < 0.5 x 10{sup -5} and {Beta}(B{sup +} {yields} D*{sup +} K{sup 0}) < 0.9 x 10{sup -5}.
Search for direct CP violation in D0→h−h+ modes using semileptonic B decays
2013
A search for direct CP violation in D0 -> h- h+ (where h=K or pi) is presented using data corresponding to an integrated luminosity of 1.0 fb^-1 collected in 2011 by LHCb in pp collisions at a centre-of-mass energy of 7 TeV. The analysis uses D0 mesons produced in inclusive semileptonic b-hadron decays to the D0 mu X final state, where the charge of the accompanying muon is used to tag the flavour of the D0 meson. The difference in the CP-violating asymmetries between the two decay channels is measured to be Delta A_CP = A_CP(K-K+) - A_CP(pi-pi+) = (0.49 +- 0.30 (stat) +- 0.14 (syst)) % . This result does not confirm the evidence for direct CP violation in the charm sector reported in other…
Precision measurement of the Λ+c baryon mass
2005
The $\Lambda_c^+$ baryon mass is measured using $\Lambda_c^+\to\Lambda K^0_S K^+$ and $\Lambda_c^+\to\Sigma^0 K^0_S K^+$ decays reconstructed in 232 fb$^{-1}$ of data collected with the BaBar detector at the PEP-II asymmetric-energy $e^+e^-$ storage ring. The $\Lambda_c^+$ mass is measured to be $2286.46\pm0.14\mathrm{MeV}/c^2$. The dominant systematic uncertainties arise from the amount of material in the tracking volume and from the magnetic field strength.
Measurement of CP asymmetries in two-body B(s)0 -meson decays to charged pions and kaons
2018
The time-dependent CP asymmetries in B0→π+π− and B0s→K+K− decays are measured using a data sample of p p collisions corresponding to an integrated luminosity of 3.0 fb−1, collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV. The same data sample is used to measure the time-integrated CP asymmetries in B0→K+π− and B0s→π+K− decays. The results are Cπ+π−=−0.34±0.06±0.01, Sπ+π−=−0.63±0.05±0.01, CK+K−=0.20±0.06±0.02, SK+K−=0.18±0.06±0.02, AΔΓK+K−=−0.79±0.07±0.10, AB0CP=−0.084±0.004±0.003, and AB0sCP=0.213±0.015±0.007, where the first uncertainties are statistical and the second systematic. Evidence for CP violation is found in the B0s→K+K− decay for the first time.
Measurements of the Λb0→J/ψΛ decay amplitudes and the Λb0 polarisation in pp collisions at s=7 TeV
2013
An angular analysis of Λ0b→J/ψΛ decays is performed using a data sample corresponding to 1.0 fb−1 collected in pp collisions at √s=7 TeV with the LHCb detector at the LHC. A parity violating asymmetry parameter characterising the Λ0b→J/ψΛ decay of 0.05±0.17±0.07 and a Λ0b transverse production polarisation of 0.06±0.07±0.02 are measured, where the first uncertainty is statistical and the second systematic.
Evidence for the Rare DecayB→K*ℓ+ℓ−and Measurement of theB→Kℓ+ℓ−Branching Fraction
2003
We present evidence for the flavor-changing neutral current decay B-->K-*.(+).(-) and a measurement of the branching fraction for the related process B-->K.(+).(-), where .(+).(-) is either an e(+)e(-) or a mu(+)mu(-) pair. These decays are highly suppressed in the standard model, and they are sensitive to contributions from new particles in the intermediate state. The data sample comprises 123x10(6) Y(4S)-->B (B) over bar decays collected with the BABAR detector at the SLAC PEP-II e(+)e(-) storage ring. Averaging over K-(*) isospin and lepton flavor, we obtain the branching fractions B(B-->Kl(+)l(-))=(0.65(-0.13)(+0.14)+/-0.04)x10(-6) and B(B-->K(*)l(+)l(-))=(0.88(-0.29)(+0.33)+/-0.10)x10(…
Quantum numbers of theX(3872)state and orbital angular momentum in itsρ0J/ψdecay
2015
Angular correlations in B+→X(3872)K+ decays, with X(3872)→ρ0J/ψ, ρ0→π+π− and J/ψ→μ+μ−, are used to measure orbital angular momentum contributions and to determine the JPC value of the X(3872) meson. The data correspond to an integrated luminosity of 3.0 fb−1 of proton-proton collisions collected with the LHCb detector. This determination, for the first time performed without assuming a value for the orbital angular momentum, confirms the quantum numbers to be JPC=1++. The X(3872) is found to decay predominantly through S wave and an upper limit of 4% at 95% C.L. is set on the fraction of D wave.
Determinations of|Vub|from Inclusive SemileptonicBDecays with Reduced Model Dependence
2006
We report two novel determinations of |V{sub ub}| with reduced model dependence, based on measurements of the mass distribution of the hadronic system in semileptonic B decays. Events are selected by fully reconstructing the decay of one B meson and identifying a charged lepton from the decay of the other B meson from {Upsilon}(4S) {yields} (B{bar B}) events. In one approach, we combine the inclusive {bar B} {yields} X{sub u}{ell}{bar {nu}} rate with a measurement of the inclusive B {yields} X{sub s}{gamma} photon energy spectrum. We obtain |V{sub ub}| = (4.43 {+-} 0.38{sub stat} {+-} 0.25{sub syst} {+-} 0.29{sub theo}) x 10{sup -3}. In another approach we measure the total {bar B} {yields}…
Precision Measurement of the Mass and Lifetime of the Ξ[0 over b] Baryon
2014
Using a proton-proton collision data sample corresponding to an integrated luminosity of 3 fb$^{-1}$ collected by LHCb at center-of-mass energies of 7 and 8 TeV, about 3800 $\Xi_b^0\to\Xi_c^+\pi^-$, $\Xi_c^+\to pK^-\pi^+$ signal decays are reconstructed. From this sample, the first measurement of the $\Xi_b^0$ baryon lifetime is made, relative to that of the $\Lambda_b^0$ baryon. The mass differences $M(\Xi_b^0)-M(\Lambda_b^0)$ and $M(\Xi_c^+)-M(\Lambda_c^+)$ are also measured with precision more than four times better than the current world averages. The resulting values are $\frac{\tau_{\Xi_b^0}}{\tau_{\Lambda_b^0}} = 1.006\pm0.018\pm0.010$, $M(\Xi_b^0) - M(\Lambda_b^0) = 172.44\pm0.39\pm…
First measurement of the charge asymmetry in beauty-quark pair production.
2014
The difference in the angular distributions between beauty quarks and antiquarks, referred to as the charge asymmetry, is measured for the first time in b[bar over b] pair production at a hadron collider. The data used correspond to an integrated luminosity of 1.0 fb[superscript −1] collected at 7 TeV center-of-mass energy in proton-proton collisions with the LHCb detector. The measurement is performed in three regions of the invariant mass of the b[bar over b] system. The results obtained are A[b[bar over b] over C](40 105 GeV/c[superscript 2]) = 1.6 ± 1.7 ± 0.6%, where A[b[bar over b] over C] is defined as the asymmetry in the difference in rapidity between jets formed from the beauty q…
Measurement of theB¯0→D*+ℓ−ν¯ℓdecay rate and|Vcb|
2005
We present a measurement of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ based on a sample of about 53,700 \mbox{$\Bzb \rightarrow D^{*+} \ell^- \bar{\nu}_{\ell}$} decays observed by the \babar\ detector. We obtain the branching fraction averaged over $\ell = e,\mu$, ${\cal B}(\Bzb \rightarrow D^{*+} \ell^- \bar{\nu}_{\ell}) = (4.90 \pm 0.07\mathrm{(stat.)}^{+0.36}_{-0.35}\mathrm{(syst.)})\%$. We measure the differential decay rate as a function of $w$, the relativistic boost $\gamma$ of the $D^{*+}$ in the ${\Bzb}$ rest frame. By extrapolating $d\Gamma/dw$ to the kinematic limit $w \rightarrow 1$, we extract the product of $|V_{cb}|$ and the axial form factor ${\cal A}_1(w=1)$. …
Amplitude analysis ofB+→J/ψϕK+decays
2017
The first full amplitude analysis of B+→J/ψϕK+ with J/ψ→μ+μ−, ϕ→K+K− decays is performed with a data sample of 3 fb−1 of pp collision data collected at s√=7 and 8 TeV with the LHCb detector. The data cannot be described by a model that contains only excited kaon states decaying into ϕK+, and four J/ψϕ structures are observed, each with significance over 5 standard deviations. The quantum numbers of these structures are determined with significance of at least 4 standard deviations. The lightest is best described as a D±sD∗∓s cusp, but a resonant interpretation is also possible with mass consistent with, but width much larger than, previous measurements of the claimed X(4140) state. The mode…
Measurement of the Difference of Time-IntegratedCPAsymmetries inD0→K−K+andD0→π−π+Decays
2016
A search for CP violation in $D^0 \rightarrow K^{-} K^{+} $ and $D^0 \rightarrow \pi^{-} \pi^{+} $ decays is performed using $pp$ collision data, corresponding to an integrated luminosity of $3~fb^{-1}$, collected using the LHCb detector at centre-of-mass energies of 7 and $8~$TeV. The flavour of the charm meson is inferred from the charge of the pion in $D^{*+}\rightarrow D^0\pi^+$ and $D^{*-}\rightarrow \bar{D^0}\pi^{-}$ decays. The difference between the CP asymmetries in $D^0 \rightarrow K^{-} K^{+} $ and $D^0 \rightarrow \pi^{-} \pi^{+} $ decays, $\Delta A_{CP} \equiv A_{CP}(K^{-} K^{+}) - A_{CP}(\pi^{-} \pi^{+})$, is measured to be $\left( -0.10 \pm 0.08(stat) \pm 0.03(syst) \right) \…
Measurements of the branching fractions and bounds on the charge asymmetries of charmless three-body charged B decays.
2003
We present measurements of branching fractions and charge asymmetries for charmless B-meson decays to three-body final states of charged pions and kaons. The analysis uses 81.8 fb^-1 of data collected at the Upsilon(4S) resonance with the BaBar detector at the SLAC PEP-II asymmetric B Factory. We measure the branching fractions B(B+ -> pi+ pi- pi+) = (10.9 +/- 3.3 +/- 1.6) x 10^-6, B(B+ -> K+ pi- pi+) = (59.1 +/- 3.8 +/- 3.2) x 10^-6, and B(B+ -> K+ K- K+) = (29.6 +/- 2.1 +/- 1.6) x 10^-6, and provide 90% C.L. upper limits for other decays. We observe no charge asymmetries for these modes.
Measurement of Time-DependentCP-Violating Asymmetries inB0→ϕKS0,K+K−KS0, andη′KS0Decays
2004
We present an improved measurement of $CP$-violation parameters in ${B}^{0}\ensuremath{\rightarrow}\ensuremath{\phi}{K}_{S}^{0}$, ${K}^{+}{K}^{\ensuremath{-}}{K}_{S}^{0}$, and ${\ensuremath{\eta}}^{\ensuremath{'}}{K}_{S}^{0}$ decays based on a $140\text{ }{\mathrm{f}\mathrm{b}}^{\ensuremath{-}1}$ data sample collected at the $\ensuremath{\Upsilon}(4S)$ resonance with the Belle detector at the KEKB energy-asymmetric ${e}^{+}{e}^{\ensuremath{-}}$ collider. One neutral $B$ meson is fully reconstructed in one of the specified decay channels, and the flavor of the accompanying $B$ meson is identified from its decay products. $CP$-violation parameters for each of the three modes are obtained from…
Measurements of branching fractions, rate asymmetries, and angular distributions in the rare decays B→K + - and B→K* + -
2006
We present measurements of the flavor-changing neutral current decays B -> K center dot(+)center dot(-) and B -> K-*center dot(+)center dot(-), where center dot(+)center dot(-) is either an e(+)e(-) or mu(+)mu(-) pair. The data sample comprises 229x10(6) Upsilon(4S)-> B (B) over bar decays collected with the BABAR detector at the PEP-II e(+)e(-) storage ring. Flavor-changing neutral current decays are highly suppressed in the standard model and their predicted properties could be significantly modified by new physics at the electroweak scale. We measure the branching fractions B(B -> K center dot(+)center dot(-))=(0.34 +/- 0.07 +/- 0.02)x10(-6), B(B -> K-*center dot(+)center dot(-))=(0.78(-…
Amplitude analysis ofB−→D+π−π−decays
2016
The Dalitz plot analysis technique is used to study the resonant substructures of $B^{-} \to D^{+} \pi^{-} \pi^{-}$ decays in a data sample corresponding to 3.0 ${\rm fb}^{-1}$ of $pp$ collision data recorded by the LHCb experiment during 2011 and 2012. A model-independent analysis of the angular moments demonstrates the presence of resonances with spins 1, 2 and 3 at high $D^{+}\pi^{-}$ mass. The data are fitted with an amplitude model composed of a quasi-model-independent function to describe the $D^{+}\pi^{-}$ S-wave together with virtual contributions from the $D^{*}(2007)^{0}$ and $B^{*0}$ states, and components corresponding to the $D^{*}_{2}(2460)^{0}$, $D^{*}_{1}(2680)^{0}$, $D^{*}_…
Measurements of the Absolute Branching Fractions of B± →k±Xc c
2020
A study of the two-body decays B±→XccK±, where Xcc refers to one charmonium state, is reported by the BABAR Collaboration using a data sample of 424 fb-1. The absolute determination of branching fractions for these decays are significantly improved compared to previous BABAR measurements. Evidence is found for the decay B+→X(3872)K+ at the 3σ level. The absolute branching fraction B[B+→X(3872)K+]=[2.1±0.6(stat)±0.3(syst)]×10-4 is measured for the first time. It follows that B[X(3872)→J/ψπ+π-]=(4.1±1.3)%, supporting the hypothesis of a molecular component for this resonance.
Measurements of the Branching Fraction andCP-Violation Asymmetries inB0→f0(980)KS0
2005
The authors present measurements of the branching fraction and CP-violating asymmetries in the decay B{sup 0} {yields} f{sub 0}(980)K{sub S}{sup 0}. The results are obtained from a data sample of 123 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays. From a time-dependent maximum likelihood fit they measure the branching fraction {Beta}(B{sup 0} {yields} f{sub 0}(980)({yields}{Pi}{sup +}{pi}{sup 0})K{sup 0}) = (6.0 {+-} 0.9 {+-} 0.6 {+-} 1.2) x 10{sup -6}, the mixing-induced CP violation parameter S = 1.62{sub -0.51}{sup +0.56} {+-} 0.09 {+-} 0.04 and the direct CP violation parameter C = 0.27 {+-} 0.36 {+-} 0.10 {+-} 0.07, where the first errors are statistical, the second systematic and …
Search forB0Decays to Invisible Final States and toνν¯γ
2004
We establish upper limits on branching fractions for B0 decays to final states where the decay products are purely invisible (i.e., no observable final state particles) and for B0 decays to nunugamma. Within the standard model, these decays have branching fractions that are below current experimental sensitivity, but various models of physics beyond the standard model predict significant contributions from these channels. Using 88.5 x 10(6) BB pairs collected at the Upsilon(4S) resonance by the BABAR experiment at the PEP-II e(+)e- storage ring at the Stanford Linear Accelerator Center, we establish upper limits at the 90% confidence level of 22 x 10(-5) for the branching fraction of B0-->i…
Observation of the Resonant Character of theZ(4430)−State
2014
Resonant structures in B-0 -> psi'pi K--(+) decays are analyzed by performing a four-dimensional fit of the decay amplitude, using pp collision data corresponding to 3 fb(-1) collected with the LHCb detector. The data cannot be described with K+pi(-) resonances alone, which is confirmed with a model-independent approach. A highly significant Z(4430)(-) -> psi'pi(-) component is required, thus confirming the existence of this state. The observed evolution of the Z(4430)(-) amplitude with the psi'pi(-) mass establishes the resonant nature of this particle. The mass and width measurements are substantially improved. The spin parity is determined unambiguously to be 1(+).
Observation of Bc+→J/ψD(*)K(*) decays
2017
A search for the decays B + c → J / ψ D ( * ) 0 K + and B + c → J / ψ D ( * ) + K * 0 is performed with data collected at the LHCb experiment corresponding to an integrated luminosity of 3 fb − 1 . The decays B + c → J / ψ D 0 K + and B + c → J / ψ D * 0 K + are observed for the first time, while first evidence is reported for the B + c → J / ψ D * + K * 0 and B + c → J / ψ D + K * 0 decays. The branching fractions of these decays are determined relative to the B + c → J / ψ π + decay. The B + c mass is measured, using the J / ψ D 0 K + final state, to be 6274.28 ± 1.40 ( stat ) ± 0.32 ( syst ) MeV / c 2 . This is the most precise single measurement of the B + c mass to date.
Study of J/ψ Production in Jets
2017
The production of $J/\psi$ mesons in jets is studied in the forward region of proton-proton collisions using data collected with the LHCb detector at a center-of-mass energy of 13 TeV. The fraction of the jet transverse momentum carried by the $J/\psi$ meson, $z \equiv p_{\rm T}(J/\psi)/p_{\rm T}({\rm jet})$, is measured using jets with $p_{\rm T}({\rm jet}) > 20$ GeV in the pseudorapidity range $2.5 < \eta({\rm jet}) < 4.0$. The observed $z$ distribution for $J/\psi$ mesons produced in $b$-hadron decays is consistent with expectations. However, the results for prompt $J/\psi$ production do not agree with predictions based on fixed-order non-relativistic QCD. This is the first measurement o…
Observation of the suppressed ADS modes B±→[π±K∓π+π−]DK± and B±→[π±K∓π+π−]Dπ±
2013
An analysis of and B-+/- -> DK +/- and B-+/- -> D pi(+/-) decays is presented where the D meson is reconstructed in the four-body final state K-+/-pi(-/+)pi(+)pi(-). Using LHCb data corresponding to an integrated luminosity of 1.0 fb(-1), first observations are made of the suppressed ADS modes B-+/- ->[pi K-+/-(-/+)pi(+)pi(-)](D)K-+/- and B +/- -> [pi K-+/-(-/+)pi(+)pi(-)](D)pi(+/-) with a significance of 5.1 sigma and greater than 10 sigma, respectively. Measurements of CP asymmetries and CP-conserving ratios of partial widths from this family of decays are also performed. The magnitude of the ratio between the suppressed and favoured B-+/- -> DK +/- amplitudes is determined to be r(B)(K) …
Measurement of the ratio ofBc+branching fractions toJ/ψπ+andJ/ψμ+νμfinal states
2014
The first measurement that relates semileptonic and hadronic decay rates of the B-c(+) meson is performed using proton-proton collision data corresponding to 1.0 fb(-1) of integrated luminosity collected with the LHCb detector. The measured value of the ratio of branching fractions, B(B-c(+) -> J/psi pi(+))/B(B-c(+) -> J/psi mu(+)nu(mu)) = 0.0469 +/- 0.0028(stat) +/- 0.0046(syst), is at the lower end of available theoretical predictions.
InclusiveΛc+production ine+e−annihilations ats=10.54 GeVand inΥ(4S)decays
2007
We present measurements of the total production rates and momentum distributions of the charmed baryon Lambda(+)(c) in e(+)e(-)-> hadrons at a center-of-mass energy of 10.54 GeV and in Upsilon(4S) decays. In hadronic events at 10.54 GeV, charmed hadrons are almost exclusively leading particles in e(+)e(-)-> cc events, allowing direct studies of c-quark fragmentation. We measure a momentum distribution for Lambda(+)(c) baryons that differs significantly from those measured previously for charmed mesons. Comparing with a number of models, we find none that can describe the distribution completely. We measure an average scaled momentum of =0.574 +/- 0.009 and a total rate of N-Lambda c(qq)=0.0…
Measurement of the Branching Fraction and Polarization for the DecayB−→D*0K*−
2004
We present a study of the decay B- --> D*K-0*(-) based on a sample of 86 X 10(6) Y(4S) --> B (B) over bar decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We measure the branching fraction 23(B- --> D*K-0*(-)) = (8.3 +/- 1.1(stat) +/- 1.0(syst)) X 10(-4), and the fraction of longitudinal polarization in this decay to be Gamma(L)/Gamma = 0.86 +/- 0.06(stat) --> +/- 0.03(syst).
Measurement of Time-DependentCPAsymmetries inB0→D(*)±D∓Decays
2005
We present updated results on time-dependent CP asymmetries in fully reconstructed B-0 -> D-(*)+/-pi(-/+) and B-0 -> D-+/-rho(-/+) decays in approximately 232x10(6) Upsilon(4S)-> B (B) over bar events collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. From a time-dependent maximum-likelihood fit we obtain for the parameters related to the CP violation angle 2 beta+gamma: a(D pi)=-0.010 +/- 0.023 +/- 0.007, c(lep)(D pi)=-0.033 +/- 0.042 +/- 0.012, a(D*)pi=-0.040 +/- 0.023 +/- 0.010, c(lep)(D*)pi=0.049 +/- 0.042 +/- 0.015,a(D rho)=-0.024 +/- 0.031 +/- 0.009, c(lep)(D rho)=-0.098 +/- 0.055 +/- 0.018, where the first error is statistical and the second is syste…
Measurement of the effective Bs0→K+K− lifetime
2012
A precise determination of the effective $B_s^0 \rightarrow K^+ K^-$ lifetime can be used to constrain contributions from physics beyond the Standard Model in the $B_s^0$ meson system. Conventional approaches select $B$ meson decay products that are significantly displaced from the $B$ meson production vertex. As a consequence, $B$ mesons with low decay times are suppressed, introducing a bias to the decay time spectrum which must be corrected. This analysis uses a technique that explicitly avoids a lifetime bias by using a neural network based trigger and event selection. Using 1.0 fb$^{-1}$ of data recorded by the LHCb experiment, the effective $B_s^0 \rightarrow K^+ K^-$ lifetime is meas…
Observation of the rare B(s)(0) + decay from the combined analysis of CMS and LHCb data.
2015
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported licence.-- et al.
Measurement of the W boson mass
1996
The W boson mass is measured using proton-proton collision data at root s = 13 TeV corresponding to an integrated luminosity of 1.7fb(-1) recorded during 2016 by the LHCb experiment. With a simultaneous fit of the muon q/p(T) distribution of a sample of W ->mu y decays and the phi* distribution of a sample of Z -> mu mu decays the W boson mass is determined to be