Branching Fraction and Charge Asymmetry Measurements InB to J/psi Pi Pi Decays PDF Download

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Languages : en
Pages : 8

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The authors study the decays B° → J/???− and B+ → J/??+?°, including intermediate resonances, using a sample of 382 million B{bar B} pairs recorded by the BABAR detector at the PEP-II e+e− B factory. They measure the branching fractions?(B° → J/??°) = (2.7 ± 0.3 ± 0.17) x 10−5 and?(B+ → J/??+) = (5.0 ± 0.7 ± 0.31) x 10−5. The authors also set the following upper limits at the 90% confidence level:?(B° → J/??+?− non-resonant)

Author: B. Aubert
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Languages : en
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The authors present measurements of the branching fraction and time-dependent CP asymmetries in B{sup 0} {yields} J/{psi} {pi}{sup 0} decays based on (231.8 {+-} 2.6) x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC during the years 1999-2004. We obtain a branching fraction {Beta}(B{sup 0} {yields} J/{psi}{pi}{sup 0}) = (1.94 {+-} 0.22 (stat) {+-} 0.17 (syst)) x 10{sup -5}. They also measure the CP asymmetry parameters C = -0.21 {+-} 0.26 (stat) {+-} 0.09 (syst) and S = -0.68 {+-} 0.30 (stat) {+-} 0.04 (syst). All results presented in this paper are preliminary.

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Languages : en
Pages : 5

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The invariance of physical laws under the combination of exchange of particles with antiparticles (charge conjugation, C) and reversal of coordinates (parity, P) is called CP symmetry. The violation of CP symmetry was first discovered in 1964 in the neutral kaon system, and is in general one of the great puzzles of particle physics. The recent observation of CP violation in the B meson system has been a simultaneous success for model predictions and experiment. The opportunity now exists to probe details of the underlying mechanisms. This thesis presents measurements of the branching fraction and time-dependent CP-violating asymmetry in neutral B decays to J/[psi][pi]°. The decay amplitude for this channel features both tree and penguin diagram contributions, the interference of which can yield a result for the asymmetry differing from that found in the ''golden mode'' B° 2!J/[psi] K{sub s}°. Using the measured branching fraction and CP asymmetry, constraints are placed on the ratio of penguin to tree amplitudes in B° 2!J/[psi][pi]°. In addition, the impact on the CP asymmetry measurement in B° 2!J/[psi] K{sub s}° is discussed. The results are presented for ee− annihilation data collected with the BABAR detector on the [Upsilon](4S) resonance at the PEP-II asymmetric-energy B Factory at SLAC. The measurement of the branching fraction, based on about 23 million B{bar B} pairs collected between October 1999 and October 2000, yields BF(B° 2!J/[psi][pi]°) = (2.0 ± 0.6 (stat) ± 0.2(syst)) x 10−5. With about 88 million B{bar B} pairs collected during the years 1999-2002, our results for the coefficients of the cosine and sine terms of the CP asymmetry are C{sub J/{psi}[pi]°} = 0.38 ± 0.41 (stat) ± 0.09 (syst) and S{sub J/{psi}[pi]°} = 0.05 ± 0.49 (stat) ± 0.16 (syst).

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Languages : en
Pages : 8

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Author: K. George
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Languages : en
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We present measurements of the branching fraction and time-dependent CP asymmetries in B{sup 0} {yields} J/{psi}{pi}{sup 0} decays based on (231.8 {+-} 2.6) x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy B factory. We obtain a branching fraction {Beta}(B{sup 0} {yields} J/{psi}{pi}{sup 0}) = (1.94 {+-} 0.22 (stat) {+-} 0.17 (syst)) x 10{sup -5}. We also measure the CP asymmetry parameters C = -0.21 {+-} 0.26 (stat) {+-} 0.06 (syst) and S = -0.68 {+-} 0.30 (stat) {+-} 0.04 (syst).

Author: J. C. Chen
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Languages : en
Pages : 9

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The authors analyze the decay B{sup 0} {yields} K{sub S}{sup 0}{pi}{sup +}{pi}{sup -} using a sample of 232 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy B factory. A maximum likelihood fit finds the following branching fractions: {Beta}(B{sup 0} {yields} K{sup 0}{pi}{sup +}{pi}{sup -}) = (43.0 {+-} 2.3 {+-} 2.3) x 10{sup -6}, {Beta}(B{sup 0} {yields} f{sub 0}({yields} {pi}{sup +}{pi}{sup -})K{sup 0}) = (5.5 {+-} 0.7 {+-} 0.5 {+-} 0.3) x 10{sup -6} and {Beta}(B{sup 0} {yields} K*{sup +}{pi}{sup -}) = (11.0 {+-} 1.5 {+-} 0.5 {+-} 0.5) x 10{sup -6}. For these results, the first uncertainty is statistical, the second is systematic, and the third (if present) is due to the effect of interference from other resonances. They also measure the CP-violating charge asymmetry in the decay B{sup 0} {yields} K*{sup +}{pi}{sup -}, {Alpha}{sub K*{pi}} = -0.11 {+-} 0.14 {+-} 0.05.

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Languages : en
Pages : 7

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The authors study B{sup ±} → J/[psi] [pi]{sup ±} and B{sup ±} → J/[psi] K{sup ±} decays in a sample of about 89 million B{bar B} pairs collected with the BABAR detector at the PEP-II asymmetric B-factory at SLAC. They observe a signal of 244 ± 20 B{sup ±} → J/[psi] [pi]{sup ±} events and determine the ratio [Beta](B{sup {+-}} → J/[psi] [pi]{sup {+-}})/[Beta](B{sup {+-}} → J/[psi] K{sup {+-}}) to be [5.37 {+-} 0.45(stat.) {+-} 0.11(syst.)]%. The charge asymmetries for the B{sup {+-}} → J/[psi] [pi]{sup {+-}} and B{sup {+-}} → J/[psi] K{sup {+-}} decays are determined to be [Alpha]{sub {pi}} = 0.123 {+-} 0.085(stat.) {+-} 0.004(syst.) and [Alpha]{sub K} = 0.030 {+-} 0.015(stat.) {+-} 0.006(syst.), respectively.

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Languages : en
Pages : 5

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We have studied the B{sup ±} → J/[psi][pi]{sup ±} and B{sup ±} → J/[psi] K{sup ±} decays using a 20.7 fb−1 data set collected with the BABAR detector. We observe a signal of 51 ± 10 B{sup ±} → J/[psi][pi]{sup ±} events and determine the ratio [Beta](B{sup {+-}} → J/[psi][pi]{sup {+-}})/[Beta](B{sup {+-}} → J/[psi] K{sup {+-}}) to be [3.91 {+-} 0.78(stat.) {+-} 0.19(syst.)]%. The CP-violating charge asymmetries for the B{sup {+-}} → J/[psi] [pi]{sup {+-}} and B{sup {+-}} → J/[psi] K{sup {+-}} decays are determined to be [Alpha]{sub {pi}} = 0.01 {+-} 0.22(stat.) {+-} 0.01(syst.) and [Alpha]{sub K} = 0.003 {+-} 0.030(stat.) {+-} 0.004(syst.).

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Languages : en
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We present a measurement of the branching fraction for the decay of the neutral B meson into the final state J/[psi][pi][sup+][pi][sup -]. The data set contains approximately 56 million B[bar B] pairs produced at the[Upsilon](4S) resonance and recorded with the BABAR detector at the PEP-II asymmetric-energy e[sup+]e[sup -] storage ring. The result of this analysis is[Beta](B[sup 0][yields] J/[psi][pi][sup+][pi][sup -])= (4.6[+-] 0.7[+-] 0.6) x 10[sup -5], where the first error is statistical and the second is systematic. In addition we measure[Beta](B[sup 0][yields] J?[psi][rho][sup 0])= (1.6[+-] 0.6[+-] 0.4) x 10[sup -5].

Author: Francesco Fobozzi
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Languages : en
Pages : 139

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The phenomenon of CP-violation in weak interactions, discovered in 1964 in decays of neutral kaons, receives a simple and elegant explanation in the Standard Model with three generations of quarks. Indeed, in this model the common source of CP-asymmetry phenomena is represented by a simple complex phase in the unitary matrix (the Cabibbo-Kobayashi-Maskawa matrix) describing the charged weak couplings of the quarks. This simple scheme has never received an accurate validation, because the phenomenological parameters determined from measurements of CP-violation in kaons decays are related to the fundamental parameters of the theory in a complex way, sensitive to large theoretical uncertainties. On the contrary, decays of neutral B mesons like B{sup 0} {yields} J/{psi} K{sub S}{sup 0} represent a unique laboratory to test the predictions of the theory because they are expected to show significant CP-violation effects, the magnitude of which is cleanly related to the Standard Model parameters. Thus experimental facilities have been built with the purpose of performing extensive studies of B decays. The BABAR experiment is operating at one of these facilities, at the Stanford Linear Accelerator Center. It is collecting data at the PEP-II asymmetric e{sup +}e{sup -} collider (E{sub e{sup -}} = 9.0 GeV; E{sub e{sup +}} = 3.1 GeV), a high-luminosity accelerator machine (L = 3 x 10{sup 33} cm{sup -2}s{sup -1}). The center-of-mass energy (10.58 GeV) of the e{sup +}e{sup -} system at PEP-II allows resonant production of the {Upsilon}(4S), a b{bar b} bound state, which decays almost exclusively in a B{sup 0}{bar B}{sup 0} or a B{sup +}B{sup -} pair. A high-acceptance detector, projected and built by a wide international collaboration, detects and characterizes the decay products of the B mesons. From the analysis of the data collected during the first two years of operation, the BABAR collaboration has established CP-violation in decays of neutral B mesons at the 4.1{sigma} level. Besides the primary goal of CP-violation studies, the high luminosity of PEP-II, coupled with the high acceptance of the BABAR detector, allows competitive studies of the properties of a wide set of B decay modes. In particular, measurements of non-leptonic decays are extremely useful to understand the dynamics of the non-perturbative strong interactions involved in these processes. In this thesis a study of the non-leptonic decay mode B{sup {+-}} {yields} J/{psi}{pi}{sup {+-}} is presented.