114 research outputs found
Search for the rare decays B^0 â D_s^((*)+)a-_(0(2))
We have searched for the decays B^0 â D_s^+a^-_0, B^0 â D_s^(*+)a^-_0, B^0 â D_s^+a^-_2 and B^0 â D_s^(*+)a^-_2 in a sample of about 230 Ă 10^6 ΄(4S) â BBÌ
decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We find no evidence for these decays and set upper limits at 90% C.L. on the branching fractions: B(B^0 â D_s^+a^-_0)<1.9 Ă 10^(-5), B(B^0 â D_s^(*+)a^-_0)<3.6 Ă 10^(-5), B(B^0 â D_s^+a^-_2)<1.9 Ă 10^(-4), and B(B^0 â D_s^(*+)a^-_2)<2.0 Ă 10^(-4)
Measurement of CP observables for the decays B^± â D^0_(CP)K^±
We present a study of the decay B^- â D^0_(CP)K^±
and its charge conjugate, where D^0_CP) is reconstructed
in CP-even, CP-odd, and non-CP flavor eigenstates, based on a sample of 232 x 10^6 Y(4S) â BB decays
collected with the BABAR detector at the PEP-II e^+e^- storage ring. We measure the partial-rate charge
asymmetries A_(CP±) and the ratios R_(CP±) of the B â D^0K decay branching fractions as measured in CP^±
and non-CP D^0 decays: A_(CP±) 0:35 ± 0.13(stat) ± 0.04(syst), A_(CP-)= -0.06 ± 0.13(stat) ±
0.04(syst), R_(CP+) = 0.90 ± 0.12(stat) ± 0.049syst), and R_(CP-) = 0:86 ± 0.10(stat) ± 0.05(syst)
Measurements of the Absolute Branching Fractions of B^±âK^±X_(cc)
We study the two-body decays of B^± mesons to K^± and a charmonium state X_cc in a sample of 210.5ââfb^(-1) of data from the BABAR experiment. We perform measurements of absolute branching fractions B(B^±âK^±X_(cc)) using a missing mass technique, and report several new or improved results. In particular, the upper limit B(B^±âK^±X(3872))4.2% will help in understanding the nature of the recently discovered X(3872)
Measurement of Branching Fractions and Resonance Contributions for B^0âD^0K^+Ï^- and Search for B^0âD^0K^+Ï^- Decays
Using 226Ă10^6 ΄(4S)âBB events collected with the BABAR detector at the PEP-II e^+e^- storage ring at the Stanford Linear Accelerator Center, we measure the branching fraction for B^0âD^0K^+Ï^-, excluding B^0âD^(*-)K^+, to be B(B^0âD^0K^+Ï^-)=(88±15±9)Ă10^(-6). We observe B^0âD^0K^*(892)^0 and B^0âD_2^*(2460)^-K^+ contributions. The ratio of branching fractions B(B^0âD^(*-)K^+)/B(B^0âD^(*-)Ï^+)=(7.76±0.34±0.29)% is measured separately. The branching fraction for the suppressed mode B^0âD^0K^+Ï^- is B(B^0âD^0K^+Ï^-)<19Ă10^(-6) at the 90% confidence level
Measurement of the inclusive electron spectrum in charmless semileptonic B decays near the kinematic end point and determination of âV_(ub)â
We present a measurement of the inclusive electron spectrum in B â X_ueÎœ decays near the kinematic limit for B â X_ceÎœ transitions, using a sample of 88 Ă 10^6 BB pairs recorded by the BABAR detector at the ΄ (4S resonance. Partial branching fraction measurements are performed in five overlapping intervals of the electron momentum; for the interval of 2.0 â 2.6 GeV/c we obtain ÎB (B â X_ueÎœ) = (0.572 ± 0.041_(stat) ± 0.065_(syst)) Ă 10^(â3). Combining this result with shape function parameters extracted from BABAR measurements of moments of the inclusive photon spectrum in B â X_sÎł decays and moments of the hadron-mass and lepton-energy spectra in B â X_câÎœ decays we determine âVub|= (4.44 ± 0.25 + 0.4_( expâ0.38SF) ± 0.22_(theory)) Ă 10^(â3). Here the first error represents the combined statistical and systematic experimental uncertainties of the partial branching fraction measurement, the second error refers to the uncertainty of the determination of the shape function parameters, and the third error is due to theoretical uncertainties in the QCD calculations
Search for the W-exchange decays B0 --> Ds(*)- Ds(*)+
We report a search for the decays , , in a sample of 232
million decays to \BBb ~pairs collected with the \babar detector
at the PEP-II asymmetric-energy storage ring. We find no significant
signal and set upper bounds for the branching fractions: and at 90% confidence level.Comment: 8 pages, 2 figures, submitted to PRD-R
Search for rare quark-annihilation decays, B --> Ds(*) Phi
We report on searches for B- --> Ds- Phi and B- --> Ds*- Phi. In the context
of the Standard Model, these decays are expected to be highly suppressed since
they proceed through annihilation of the b and u-bar quarks in the B- meson.
Our results are based on 234 million Upsilon(4S) --> B Bbar decays collected
with the BABAR detector at SLAC. We find no evidence for these decays, and we
set Bayesian 90% confidence level upper limits on the branching fractions BF(B-
--> Ds- Phi) Ds*- Phi)<1.2x10^(-5). These results
are consistent with Standard Model expectations.Comment: 8 pages, 3 postscript figues, submitted to Phys. Rev. D (Rapid
Communications
The Physics of the B Factories
âThe Physics of the B Factoriesâ describes a decade long
effort of physicists in the quest for the precise determination
of asymmetry â broken symmetry â between particles
and anti-particles. We now recognize that the matter
we see around us is the residue â one part in a billion
â of the matter and antimatter that existed in the
early universe, most of which annihilated into the cosmic
background radiation that bathes us. But the question remains:
how did the baryonic matter-antimatter asymmetry
arise? This book describes the work done by some 1000
physicists and engineers from around the globe on two
experimental facilities built to test our understanding of
this phenomenon, one at the SLAC National Accelerator
Laboratory in California, USA, and a second at the KEK
Laboratory, Tsukuba, Japan, and what we have learned
from them in broadening our understanding of nature
The Physics of the B Factories
This work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C
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