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Title: Study of Branching Fractions and CP-Violating Asymmetries in B Meson Decays to Rho And Pion Final State with the BABAR Detector

Abstract

We present measurements of branching fractions and CP-violating asymmetries in B-meson decays to {rho}{sup +}{pi}{sup 0}, {rho}{sup 0}{pi}{sup +} and {rho}{sup 0}{pi}{sup 0}. The data sample comprises 89 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. We find the charge-averaged branching fractions {Beta}(B{sup +} {yields} {rho}{sup +}{pi}{sup 0}) = (10.9 {+-} 1.9(stat) {+-} 1.9(syst)) x 10{sup -6} and {Beta}(B{sup 0} {yields} {rho}{sup 0}{pi}{sup +}) = (9.5 {+-} 1.1 {+-} 0.9) x 10{sup -6}, and we set a 90% confidence-level upper limit {Beta}(B{sup 0} {yields} {rho}{sup 0}{pi}{sup 0}) < 2.9 x 10{sup -6}. We measure the charge asymmetries A{sub CP}{rho}{sup +}{pi}{sup 0} = 0.24 {+-} 0.16 {+-} 0.06 and {Alpha}{sub CP}{sup {rho}{sup 0}{pi}{sup +}} = -0.19 {+-} 0.11 {+-} 0.02. We also present the preliminary measurement of CP-violating asymmetries in B{sup 0} {yields} ({rho}{pi}){sup 0} {yields} {pi}{sup +}{pi}{sup -}{pi}{sup 0} decays using a time-dependent Dalitz plot analysis. The results are obtained from a data sample of 213 million {Upsilon}(4S) {yields} B{bar B} decays, collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. This analysis extends the narrow-{rho} quasi-two-body approximation used in the previous analysis,more » by taking into account the interference between the {rho} resonances of the three charges. We measure 16 coefficients of the bilinear form factor terms occurring in the time-dependent decay rate of the B{sup 0} meson with the use of a maximum-likelihood fit. We derive the physically relevant quantities from these coefficients. We measure the direct CP-violation parameters {Alpha}{sub {rho}{pi}} = -0.088 {+-} 0.049 {+-} 0.013 and C = 0.34 {+-} 0.11 {+-} 0.05, where the first errors are statistical and the second systematic. For the mixing-induced CP-violation parameter we find S = -0.10 {+-} 0.14 {+-} 0.04, and for the dilution and strong phase shift parameters respectively, we obtain {Delta}C = 0.15 {+-} 0.11 {+-} 0.03 and {Delta}S = 0.22 {+-} 0.15 {+-} 0.03. For the angle {alpha} of the Unitarity Triangle we measure (113{sub -17}{sup +27} {+-} 6){sup o}; only a weak constraint is achieved at the significance level of more than two standard deviations. Finally, for the relative strong phase {delta}{sub +-} between the B{sup 0} {yields} {rho}{sup -}{pi}{sup +} and B{sup 0} {yields} {rho}{sup +}{pi}{sup -} transitions we find (-67{sub -31}{sup +28} {+-} 7){sup o}, with a similarly weak constraint at two standard deviations and beyond.« less

Authors:
;
Publication Date:
Research Org.:
Stanford Linear Accelerator Center (SLAC)
Sponsoring Org.:
USDOE
OSTI Identifier:
877968
Report Number(s):
SLAC-R-811
TRN: US200611%%153
DOE Contract Number:
AC02-76SF00515
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; B MESONS; DALITZ PLOT; DECAY; DILUTION; FORM FACTORS; MAXIMUM-LIKELIHOOD FIT; MESONS; PHASE SHIFT; PIONS; STANFORD LINEAR ACCELERATOR CENTER; UNITARITY; Experiment-HEP,HEPEX

Citation Formats

Wu, Jinwei, and /Wisconsin U., Madison. Study of Branching Fractions and CP-Violating Asymmetries in B Meson Decays to Rho And Pion Final State with the BABAR Detector. United States: N. p., 2006. Web. doi:10.2172/877968.
Wu, Jinwei, & /Wisconsin U., Madison. Study of Branching Fractions and CP-Violating Asymmetries in B Meson Decays to Rho And Pion Final State with the BABAR Detector. United States. doi:10.2172/877968.
Wu, Jinwei, and /Wisconsin U., Madison. Wed . "Study of Branching Fractions and CP-Violating Asymmetries in B Meson Decays to Rho And Pion Final State with the BABAR Detector". United States. doi:10.2172/877968. https://www.osti.gov/servlets/purl/877968.
@article{osti_877968,
title = {Study of Branching Fractions and CP-Violating Asymmetries in B Meson Decays to Rho And Pion Final State with the BABAR Detector},
author = {Wu, Jinwei and /Wisconsin U., Madison},
abstractNote = {We present measurements of branching fractions and CP-violating asymmetries in B-meson decays to {rho}{sup +}{pi}{sup 0}, {rho}{sup 0}{pi}{sup +} and {rho}{sup 0}{pi}{sup 0}. The data sample comprises 89 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. We find the charge-averaged branching fractions {Beta}(B{sup +} {yields} {rho}{sup +}{pi}{sup 0}) = (10.9 {+-} 1.9(stat) {+-} 1.9(syst)) x 10{sup -6} and {Beta}(B{sup 0} {yields} {rho}{sup 0}{pi}{sup +}) = (9.5 {+-} 1.1 {+-} 0.9) x 10{sup -6}, and we set a 90% confidence-level upper limit {Beta}(B{sup 0} {yields} {rho}{sup 0}{pi}{sup 0}) < 2.9 x 10{sup -6}. We measure the charge asymmetries A{sub CP}{rho}{sup +}{pi}{sup 0} = 0.24 {+-} 0.16 {+-} 0.06 and {Alpha}{sub CP}{sup {rho}{sup 0}{pi}{sup +}} = -0.19 {+-} 0.11 {+-} 0.02. We also present the preliminary measurement of CP-violating asymmetries in B{sup 0} {yields} ({rho}{pi}){sup 0} {yields} {pi}{sup +}{pi}{sup -}{pi}{sup 0} decays using a time-dependent Dalitz plot analysis. The results are obtained from a data sample of 213 million {Upsilon}(4S) {yields} B{bar B} decays, collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. This analysis extends the narrow-{rho} quasi-two-body approximation used in the previous analysis, by taking into account the interference between the {rho} resonances of the three charges. We measure 16 coefficients of the bilinear form factor terms occurring in the time-dependent decay rate of the B{sup 0} meson with the use of a maximum-likelihood fit. We derive the physically relevant quantities from these coefficients. We measure the direct CP-violation parameters {Alpha}{sub {rho}{pi}} = -0.088 {+-} 0.049 {+-} 0.013 and C = 0.34 {+-} 0.11 {+-} 0.05, where the first errors are statistical and the second systematic. For the mixing-induced CP-violation parameter we find S = -0.10 {+-} 0.14 {+-} 0.04, and for the dilution and strong phase shift parameters respectively, we obtain {Delta}C = 0.15 {+-} 0.11 {+-} 0.03 and {Delta}S = 0.22 {+-} 0.15 {+-} 0.03. For the angle {alpha} of the Unitarity Triangle we measure (113{sub -17}{sup +27} {+-} 6){sup o}; only a weak constraint is achieved at the significance level of more than two standard deviations. Finally, for the relative strong phase {delta}{sub +-} between the B{sup 0} {yields} {rho}{sup -}{pi}{sup +} and B{sup 0} {yields} {rho}{sup +}{pi}{sup -} transitions we find (-67{sub -31}{sup +28} {+-} 7){sup o}, with a similarly weak constraint at two standard deviations and beyond.},
doi = {10.2172/877968},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Mar 22 00:00:00 EST 2006},
month = {Wed Mar 22 00:00:00 EST 2006}
}

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  • This dissertation describes the measurement of branching fractions and CP asymmetries in neutral B meson decays to charmless two-body final states of charged pions and kaons. CP violation is a poorly-constrained phenomenon in the Standard model (SM) of particle physics and had been studied only in the kaon system before the Babar and Belle experiments. The decay of the neutral B meson to charged pions and kaons is particularly useful for the study of CP violation because they can be related to the Unitarity Triangle angle {alpha}.
  • This dissertation presents a measurement of CP asymmetries and branching fractions for neutral B meson decays to two-body final states of charged pions and kaons. The results are obtained from a data sample of about 88 million {Upsilon}(4S) {yields} B{bar B} decays collected between 1999 and 2002 with the BABAR detector at the PEP-II asymmetric-energy B factory located at the Stanford Linear Accelerator Center. A fit to kinematic, topological, and particle identification information measures the charge-averaged branching fractions {Beta}(B{sup 0} {yields} {pi}{sup +}{pi}{sup -}) = (4.7 {+-} 0.6 {+-} 0.2) x 10{sup -6} and {Beta}(B{sup 0} {yields} K{sup +}{pi}{sup -})more » = (17.9 {+-} 0.9 {+-} 0.7) x 10{sup -6}; the 90% confidence level upper limit {Beta}(B{sup 0} {yields} K{sup +}K{sup -}) < 0.6 x 10{sup -6}; and the direct CP-violating charge asymmetry {Alpha}{sub K{pi}} = -0.102 {+-} 0.050 {+-} 0.016 [-0.188, -0.016], where the first uncertainties are statistical and the second are systematic and the ranges in square brackets indicate the 90% confidence interval. A fit which adds decay time and b-flavor tagging information measures the CP-violating parameters for B{sup 0} {yields} {pi}{sup +}{pi}{sup -} decays S{sub {pi}{pi}} = 0.02 {+-} 0.34 {+-} 0.05 [-0.54, +0.58] and C{sub {pi}{pi}} = -0.30 {+-} 0.25 {+-} 0.04 [-0.72, +0.12].« less
  • The authors present measurements of branching ratios and CP-violating asymmetries for neutral B decays into quasi two-body final states dominated by the modes {rho}{sup {+-}}{pi}{sup {-+}} and {rho}{sup {+-}}K{sup {-+}}. The data set used for these measurements was recorded during the 1999-2002 period, and corresponds to a total integrated luminosity of 81.9 fb{sup -1} taken on the {Upsilon}(4S) peak, and 9.5 fb{sup -1} taken 40 MeV off-peak. From a time-dependent maximum likelihood fit they find for the branching fractions {Beta}({rho}{sup 2}{pi}{sup {-+}}) = (22.6 {+-} 1.8(stat) {+-} 2.2(syst)) x 10{sup -6}, {Beta}({rho}{sup {+-}}K{sup {-+}}) = (7.3{sub -1.2}{sup +1.3}(stat) {+-} 1.3(syst))more » x 10{sup -6}. For the CP violation parameters, they measure: {Alpha}{sub CP}{sup pK} = 0.28 {+-} 0.17(stat) {+-} 0.080(syst), {Alpha}{sub CP}{sup pk} = -0.18 {+-} 0.08(stat) {+-} 0.029(syst), C{sub pk} = 0.36 {+-} 0.18(stat) {+-} 0.041(syst), S{sub pt} = 0.19 {+-} 0.24(stat) {+-} 0.031(syst), and for the remaining parameters, required to fully describe the time dependence of the B{sup 0}({bar B}{sup 0} {yields} {rho}{sup {+-}}{pi}{sup {-+}}) decays, they obtain {Delta}C{sub pn} = 0.28{sub -0.19}{sup +0.18}(stat) {+-} 0.043(syst), {Delta}S{sub pk} = 0.15 {+-} 0.25(stat) {+-} 0.025(syst).« less
  • The authors present preliminary measurements of branching fractions and CP-violating charge asymmetries in B-meson decays to {rho}{pi}. The data sample comprises 89 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factor at SLAC. They find the charge-averaged branching fractions {Beta}(B{sup +} {yields} {rho}{sup +}{pi}{sup 0}) = (11.0 {+-} 1.9(stat.) {+-} 1.9(syst.)) x 10{sup -6} and {Beta}(B{sup +} {yields} {rho}{sup 0}{pi}{sup +}) = (9.3 {+-} 1.0(stat.) {+-} 0.8(syst.)) x 10{sup -6}; they set a 90% confidence-level upper limit of {Beta}(B{sup 0} {yields} {rho}{sup 0}{pi}{sup 0}) < 2.5 x 10{sup -6}. They measure themore » CP-violating charge asymmetries A{sub CP}{sup {rho}{sup +}{pi}{sup 0}} = 0.23 {+-} 0.16(stat.) {+-} 0.06(syst.) and A{sub CP}{sup {rho}{sup 0}{pi}{sup +}} = -0.17 {+-} 0.11(stat.) {+-} 0.02(syst.).« less
  • The authors have reconstructed B{sup -} --> D{sup 0}K{sup -} decays with D{sup 0} mesons decaying to non-CP (K{sup -}{pi}{sup +}), CD-even (K{sup -}K{sup +}, {pi}{sup -}{pi}{sup +}) and CP-odd (K{sup 0}{sub s}{pi}{sup 0}) eigenstates. They have measured the CP asymmetries A{sub CP{sup +}} = 0.40 {+-} 0.15(stat) {+-} 0.08(syst), A{sup CP{sup -}} = 0.21 {+-} 0.17(stat) {+-} 0.07(syst), and the double ratio of branching fractions R{sub +} = 0.87 {+-} 0.14(stat) {+-} 0.06(syst), R{sub -} = 0.80 {+-} 0.14(stat) {+-} 0.08(syst). These results improve the previous existing measurements from BABAR. All results presented in this document are preliminary.