Search results for "decay"
showing 10 items of 2087 documents
Search forB+→τ+νdecays with hadronicBtags
2008
We present a search for the decay B{sup +}{yields}{tau}{sup +}{nu} using 383x10{sup 6} BB pairs collected at the {upsilon}(4S) resonance with the BABAR detector at the SLAC PEP-II B Factory. We select a sample of events with one completely reconstructed tag B in a hadronic decay mode (B{sup -}{yields}D{sup (*)0}X{sup -}), and examine the rest of the event to search for a B{sup +}{yields}{tau}{sup +}{nu} decay. We identify the {tau} lepton in the following modes: {tau}{sup +}{yields}e{sup +}{nu}{nu}, {tau}{sup +}{yields}{mu}{sup +}{nu}{nu}, {tau}{sup +}{yields}{pi}{sup +}{nu}, and {tau}{sup +}{yields}{pi}{sup +}{pi}{sup 0}{nu}. We find a 2.2{sigma} excess in data and measure a branching frac…
Measurement of theB+→pp¯K+branching fraction and study of the decay dynamics
2005
With a sample of 232x10^6 Upsilon(4S) --> BBbar events collected with the BaBar detector, we study the decay B+ --> p pbar K+ excluding charmonium decays to ppbar. We measure a branching fraction Br(B+ --> p pbar K+)=(6.7+/-0.5+/-0.4)x10^{-6}. An enhancement at low ppbar mass is observed and the Dalitz plot asymmetry suggests dominance of the penguin amplitude in this B decay. We search for a pentaquark candidate Theta*++ decaying into pK+ in the mass range 1.43 to 2.00 GeV/c2 and set limits on Br(B+ --> Theta*++pbar)xBr(Theta*++ --> pK+) at the 10^{-7} level.
Search for B^{+}→τ^{+}ν
2007
We present a search for the decay B + → τ + ν using 383 × 10 6 B ¯¯¯ B pairs collected at the Υ ( 4 S ) resonance with the BABAR detector at the SLAC PEP-II B -Factory. A sample of events with one reconstructed semileptonic B decay ( B − → D 0 ℓ − ¯ ν ℓ X ) is selected, and in the recoil a search for B + → τ + ν is performed. The τ is identified in the following channels: τ + → e + ν ¯ ν , τ + → μ + ν ¯ ν , τ + → π + ¯ ν , and τ + → π + π 0 ¯ ν . We measure a branching fraction of B ( B + → τ + ν ) = ( 0.9 ± 0.6 ( stat . ) ± 0.1 ( syst . ) ) × 10 − 4 . In the absence of a significant signal, we calculate an upper limit at the 90% confidence level of B ( B + → τ + ν ) < 1.7 × 10 − 4 . We cal…
Measurement of the branching fraction andΛ¯polarization inB0→Λ¯pπ−
2009
We present a measurement of the B0 --> Lambda-bar p pi- branching fraction performed using the BaBar detector at the PEP-II asymmetric e+e- collider. Based on a sample of 467 million BB-bar pairs we measure B(B0 --> Lambda-bar p pi-) = [3.07 pm 0.31 (stat.) pm 0.23 (syst.)] x 10^{-6}. The measured differential spectrum as a function of the dibaryon invariant mass m(Lambda p) shows a near-threshold enhancement similar to that observed in other baryonic B decays. We study the Lambda-bar polarization as a function of Lambda-bar energy in the B0 rest frame (E*_Lambda) and compare it with theoretical expectations of fully longitudinally right-polarized Lambda-bar at large E*_Lambda.
Measurement ofCPviolation observables and parameters for the decaysB±→DK*±
2009
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 …
Branching fraction and charge asymmetry measurements in B→J/ψππ decays
2007
The authors study the decays B{sup 0} {yields} J/{psi} {pi}{sup +}{pi}{sup -} and B{sup +} {yields} J/{psi} {pi}{sup +}{pi}{sup 0}, including intermediate resonances, using a sample of 382 million B{bar B} pairs recorded by the BABAR detector at the PEP-II e{sup +}e{sup -} B factory. They measure the branching fractions {Beta}(B{sup 0} {yields} J/{psi} {rho}{sup 0}) = (2.7 {+-} 0.3 {+-} 0.17) x 10{sup -5} and {Beta}(B{sup +} {yields} J/{psi} {rho}{sup +}) = (5.0 {+-} 0.7 {+-} 0.31) x 10{sup -5}. The authors also set the following upper limits at the 90% confidence level: {Beta}(B{sup 0} {yields} J/{psi} {pi}{sup +}{pi}{sup -} non-resonant) < 1.2 x 10{sup -5}, {Beta}(B{sup 0} {yields} J/{psi…
Search for the rare decay Bs 0→μ+μ-
2010
We present the results of a search for the flavor changing neutral current decay B-s(0) -> mu(+)mu(-) using 6.1 fb(-1) of p (p) over bar collisions at root s = 1.96 TeV collected by the D0 experiment at the Fermilab Tevatron Collider. The observed number of B-s(0) candidates is consistent with background expectations. The resulting upper limit on the branching fraction is B(B-s(0) -> mu(+)mu(-)) < 5.1 x 10(-8) at the 95% C.L. This limit is a factor of 2.4 better than that of the previous DO analysis and the best limit to date. Published by Elsevier B.V.
Prospects for the Zee-Babu Model at the LHC and low energy experiments
2007
We analyze the viability of the Zee-Babu model as an explanation of observed neutrino masses and mixings and the possibility that the model is confirmed or discarded in experiments planned for the very close future. The allowed parameter space is studied analytically by using some approximations and partial data. Then, a complete scanning of all parameters and constraints is performed numerically by using Monte Carlo methods. The cleanest signal of the model will be the detection of the doubly charged scalar at the LHC and its correlation with measurements of the branching ratio of $\mu\to e\gamma$ at the MEG experiment. In addition, the model offers interesting predictions for $\tau^{-}\to…
Time-dependent and time-integrated angular analysis ofB→φKS0π0andφK±π∓
2008
We perform a time-dependent and time-integrated angular analysis of the B{sup 0} {yields} {psi}K*(892){sup 0}, {psi}K*{sub 2}(1430{sup 0}), and {psi}(K{pi}){sub S-wave}{sup 0} decays with the final sample of about 465 million B{bar B} pairs recorded with the BABAR detector. Overall, twelve parameters are measured for the vector-vector decay, nine parameters for the vector-tensor decay, and three parameters for the vector-scalar decay, including the branching fractions, CP-violation parameters, and parameters sensitive to final state interaction. We use the dependence on the K{pi} invariant mass of the interference between the scalar and vector or tensor components to resolve discrete ambigu…
Dalitz plot analysis of the decay B±→K±K±K∓
2006
We analyze the three-body charmless decay B-+/-->(KKK -/+)-K-+/--K-+/- using a sample of 226.0 +/- 2.5 million B (B) over bar pairs collected by the BABAR detector. We measure the total branching fraction and CP asymmetry to be B=(35.2 +/- 0.9 +/- 1.6)x10(-6) and A(CP)=(-1.7 +/- 2.6 +/- 1.5)%. We fit the Dalitz plot distribution using an isobar model and measure the magnitudes and phases of the decay coefficients. We find no evidence of CP violation for the individual components of the isobar model. The decay dynamics is dominated by the K+K- S-wave, for which we perform a partial-wave analysis in the region m(K+K-)< 2 GeV/c(2). Significant production of the f(0)(980) resonance, and of a sp…