2,012 research outputs found
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Improved Measurement of CP Violation in Neutral BDecays to \ccbar s
The authors present updated measurements of time-dependent CP asymmetries in fully-reconstructed neutral B decays to several CP eigenstates containing a charmonium meson. The measurements use a data sample of (383 {+-} 4) x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II B factory. They determine sin2{beta} = 0.714 {+-} 0.032(stat) {+-} 0.018(syst) and |{lambda}| = 0.952 {+-} 0.022(stat) {+-} 0.017(syst)
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Search for a Narrow Resonance in e e- to Four Lepton Final States
Motivated by recent models proposing a hidden sector with {approx} GeV scale force carriers, we present a search for a narrow dilepton resonance in 4 lepton final states using 536 fb{sup -1} collected by the BABAR detector. We search for the reaction, e{sup +}e{sup -} {yields} W{prime}W{prime} {yields} (l{sup +}l{sup -})(l{prime}{sup +}l{prime}{sup -}), where the leptons carry the full 4-momentum and the two dilepton pair invariant masses are equal. We do not observe a significant signal and we set 90% upper limits of {sigma}(e{sup +}e{sup -} {yields} W{prime}W{prime} {yields} e{sup +}e{sup -}e{sup +}e{sup -}) < (15-70) ab, {sigma}(e{sup +}e{sup -} {yields} W{prime}W{prime} {yields} e{sup +}e{sup -}{mu}{sup +}{mu}{sup -} < (15-40) ab, and {sigma}(e{sup +}e{sup -} {yields} W{prime}W{prime} {yields} {mu}{sup +}{mu}{sup -}{mu}{sup +}{mu}{sup -}) < 11-17) ab in the W{prime} mass range between 0.24 and 5.3GeV/c{sup 2}. Under the assumption that the W{prime} coupling to electrons and muons is the same, we obtain a combined upper limit of {sigma}e{sup +}e{sup -} {yields} W{prime}W{prime} {yields} l{sup +}l{sup -}l{prime}{sup +}l{prime}{sup -} < (25-60) ab. Using these limits, we constrain the product of the SM-dark sector mixing and the dark coupling constant in the case of a non-Abelian Higgsed dark sector
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Evidence for Charged B Meson Decays toa_1+/-(1260)pi0 and a_10(1260)pi+/-
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Branching Fraction and Form-factor Shape Measurements of Exclusive Charmless Semileptonic B Decays, and Determination of |Vub|
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Measurements of time-dependent CP asymmetries in B0 --> D(*)+D(*)- decays
We present new measurements of time-dependent CP asymmetries for B{sup 0} {yields} D{sup (*)+}d{sup (*)-} decays using (467 {+-} 5) x 10{sup 6} B{bar B} pairs collected with the BABAR detector located at the PEP-II B Factory at the Stanford Linear Accelerator Center. We determine the CP-odd fraction of the B{sup 0} {yields} D*{sup +}D*{sup -} decays to be R{perpendicular} = 0.158 {+-} 0.028 {+-} 0.006 and find CP asymmetry parameters for the CP-even component of the decay S{sub +} = -0.76 {+-} 0.16 {+-} 0.04 and C{sub +} = 0.00 {+-} 0.12 {+-} 0.02. We measure S = -0.63{+-}0.36{+-}0.05 and C = -0.07{+-}0.23{+-}0.03 for B{sup 0} {yields} D{sup +}D{sup -}, S = -0.62{+-}0.21{+-}0.03 and C = 0.08 {+-} 0.17 {+-} 0.04 for B{sup 0} {yields} D*{sup +}D{sup -}, and S = -0.73 {+-} 0.23 {+-} 0.05 and C = 0.00 {+-} 0.17 {+-} 0.03 for B{sup 0} {yields} D{sup +}D*{sup -}. For the B{sup 0} {yields} D*{sup {+-}}D{sup {-+}} decays, we also determine the CP-violating asymmetry A = 0.008 {+-} 0.048 {+-} 0.013. In each case, the first uncertainty is statistical and the second is systematic. The measured values for the asymmetries are all consistent with the Standard Model
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Measurement of Branching Fractions of B0 Decays to K1(1270)+ pi- and K1(1400)+ pi-
We present a measurement of the branching fraction of neutral B meson decaying to final states containing a K1 meson, i.e. K{sub 1}(1270) and K{sub 1}(1400), and a charged pion. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 454 million B{bar B} pairs produced in e{sup +}e{sup -} annihilation. We measure the branching fraction {Beta}(B{sup 0} {yields} K{sub 1}{sup +}{pi}{sup -}) = (31.0 {+-} 2.7 {+-} 6.9) x 10{sup -6}, where the first error quoted is statistical and the second is systematic. In the framework of the K-matrix formalism used to describe these decays, we also set limits on the ratio of the production constants for the K{sub 1}(1270){sup +} and K{sub 1}(1400){sup +} mesons in B{sup 0} decays
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Amplitude Analysis of the Decay B0->K+pi-pi0
We report an updated amplitude analysis of the charmless hadronic decays of neutral B mesons to K{sup +} {pi}{sup -}{pi}{sup 0}. With a sample of 454 million {Upsilon}(4S) {yields} B{bar B} decays collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC, we measure the magnitudes and phases of the intermediate resonant and nonresonant amplitudes for B{sup 0} and B{sup 0} decays and determine the corresponding CP-averaged fit fractions and charge asymmetries
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Measurement of Ratios of Branching Fractions and CP-Violating Asymmetries of B+/- --> D*K +/- decays
The authors report a study of B{sup {+-}} {yields} D*K{sup {+-}} decays with D* decaying to D{pi}{sup 0} or D{gamma}, using 383 x 10{sup 6} B{bar B} pairs collected at the {Upsilon}(4S) resonance with the BABAR detector at the SLAC PEP-II B-Factory. The D meson decays under study include a non-CP mode (K{sup {+-}}{pi}{sup {-+}}), CP-even modes (K{sup {+-}}K{sup {-+}}, {pi}{sup {+-}}{pi}{sup {-+}}) and CP-odd modes (K{sub S}{sup 0}{pi}{sup 0}, K{sub S}{sup 0}{phi}, K{sub S}{sup 0}{omega}). They measure ratios (R*{sub CP{+-}}) of branching fractions of decays to CP eigenmode states and to flavor-specific states as well as CP asymmetries A*{sub CP{+-}} = -0.11 {+-} 0.09 {+-} 0.01, R*{sub CP+} = 1.31 {+-} 0.13 {+-} 0.04, and A*{sub CP-} = 0.06 {+-} 0.10 {+-} 0.02, R*{sub CP-} = 1.10 {+-} 0.12 {+-} 0.04, where the first error is statistical and the second error is systematic. Translating the results into an alternative parameterization, widely used for related measurements, they obtain x*{sub +} = 0.11 {+-} 0.06 {+-} 0.02 and x*{sub -} = 0.00 {+-} 0.06 {+-} 0.01. No significant CP-violating charge asymmetry is found in either the flavor-specific mode D {yields} K{sup {+-}}{pi}{sup {-+}} or in B{sup {+-}} {yields} D*{pi}{sup {+-}} decays
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