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Title: CP asymmetry in B{sup 0}(t){yields}K{sub S}{pi}{sup 0}{gamma} in the standard model

Abstract

The time-dependent CP asymmetry in exclusive B{sup 0}(t){yields}K*{sup 0}{gamma} decays has been proposed as a probe of new physics in B decays. Recently, this method was extended to radiative decays into multibody hadronic final states such as B{sup 0}(t){yields}K{sub S}{pi}{sup 0}{gamma} and B{sup 0}(t){yields}{pi}{sup +}{pi}{sup -}{gamma}. The CP asymmetry in these decays vanishes to the extent that the photon is completely polarized. In the standard model, the photon emitted in b{yields}s{gamma} has high left-handed polarization, but right-handed contamination enters already at leading order in {lambda}/m{sub b} even for vanishing light quark masses. We compute here the magnitude of this effect and the time-dependent CP asymmetry parameter S{sub K{sub S}}{sub {pi}}{sub {sup 0}}{sub {gamma}}. We find that the standard model can easily accommodate values of S as large as 10%, but a precise value cannot be obtained at present because of strong interactions uncertainties.

Authors:
;  [1];  [2]
  1. Department of Physics, University of California at San Diego, La Jolla, California 92093 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20774598
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 73; Journal Issue: 1; Other Information: DOI: 10.1103/PhysRevD.73.014013; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ASYMMETRY; B NEUTRAL MESONS; B QUARKS; CP INVARIANCE; D QUARKS; HADRONIC PARTICLE DECAY; PHOTONS; PIONS MINUS; PIONS PLUS; POLARIZATION; RADIATIVE DECAY; REST MASS; S QUARKS; STANDARD MODEL; STRONG INTERACTIONS; TIME DEPENDENCE; U QUARKS

Citation Formats

Grinstein, Benjamin, Pirjol, Dan, and Center for Theoretical Physics, Massachusetts Institute for Technology, Cambridge, Massachusetts 02139. CP asymmetry in B{sup 0}(t){yields}K{sub S}{pi}{sup 0}{gamma} in the standard model. United States: N. p., 2006. Web. doi:10.1103/PhysRevD.73.014013.
Grinstein, Benjamin, Pirjol, Dan, & Center for Theoretical Physics, Massachusetts Institute for Technology, Cambridge, Massachusetts 02139. CP asymmetry in B{sup 0}(t){yields}K{sub S}{pi}{sup 0}{gamma} in the standard model. United States. doi:10.1103/PhysRevD.73.014013.
Grinstein, Benjamin, Pirjol, Dan, and Center for Theoretical Physics, Massachusetts Institute for Technology, Cambridge, Massachusetts 02139. Sun . "CP asymmetry in B{sup 0}(t){yields}K{sub S}{pi}{sup 0}{gamma} in the standard model". United States. doi:10.1103/PhysRevD.73.014013.
@article{osti_20774598,
title = {CP asymmetry in B{sup 0}(t){yields}K{sub S}{pi}{sup 0}{gamma} in the standard model},
author = {Grinstein, Benjamin and Pirjol, Dan and Center for Theoretical Physics, Massachusetts Institute for Technology, Cambridge, Massachusetts 02139},
abstractNote = {The time-dependent CP asymmetry in exclusive B{sup 0}(t){yields}K*{sup 0}{gamma} decays has been proposed as a probe of new physics in B decays. Recently, this method was extended to radiative decays into multibody hadronic final states such as B{sup 0}(t){yields}K{sub S}{pi}{sup 0}{gamma} and B{sup 0}(t){yields}{pi}{sup +}{pi}{sup -}{gamma}. The CP asymmetry in these decays vanishes to the extent that the photon is completely polarized. In the standard model, the photon emitted in b{yields}s{gamma} has high left-handed polarization, but right-handed contamination enters already at leading order in {lambda}/m{sub b} even for vanishing light quark masses. We compute here the magnitude of this effect and the time-dependent CP asymmetry parameter S{sub K{sub S}}{sub {pi}}{sub {sup 0}}{sub {gamma}}. We find that the standard model can easily accommodate values of S as large as 10%, but a precise value cannot be obtained at present because of strong interactions uncertainties.},
doi = {10.1103/PhysRevD.73.014013},
journal = {Physical Review. D, Particles Fields},
number = 1,
volume = 73,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • We present a new measurement of CP-violation parameters in B{sup 0}{yields}K{sub S}{sup 0}{pi}{sup 0}{gamma} decay based on a sample of 275x10{sup 6} BB pairs collected at the {upsilon}(4S) resonance with the Belle detector at the KEKB energy-asymmetric e{sup +}e{sup -} collider. One of the B mesons is fully reconstructed in the B{sup 0}{yields}K{sub S}{sup 0}{pi}{sup 0}{gamma} decay. The flavor of the accompanying B meson is identified from its decay products. CP-violation parameters are obtained from the asymmetry in the distribution of the proper time intervals between the two B decays. We obtain S{sub K{sub S}}{sub {sup 0}}{sub {pi}}{sub {sup 0}}{submore » {gamma}}=-0.58{sub -0.38}{sup +0.46}(stat){+-}0.11(syst) and A{sub K{sub S}}{sub {sup 0}}{sub {pi}}{sub {sup 0}}{sub {gamma}}=+0.03{+-}0.34(stat){+-}0.11(syst), for the K{sub S}{sup 0}{pi}{sup 0} invariant mass covering the full range up to 1.8 GeV/c{sup 2}. We also measure the CP-violation parameters for the case B{sup 0}{yields}K*{sup 0}({yields}K{sub S}{sup 0}{pi}{sup 0}){gamma} and obtain S{sub K{sup *}}{sub {sup 0}}{sub {gamma}}=-0.79{sub -0.50}{sup +0.63}(stat){+-}0.10(syst) for A{sub K{sup *}}{sub {sup 0}}{sub {gamma}} fixed at 0.« less
  • We present a measurement of the time-dependent CP-violating asymmetry in B{sup 0}{yields}K*{sup 0}{gamma} decays with K*{sup 0}{yields}K{sub S}{sup 0}{pi}{sup 0} based on 232x10{sup 6} {upsilon}(4S){yields}BB decays collected with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at SLAC. In a sample containing 157{+-}16 signal decays, we measure S{sub K*{sup 0}}{sub {gamma}}=-0.21{+-}0.40{+-}0.05 and C{sub K*{sup 0}}{sub {gamma}}=-0.40{+-}0.23{+-}0.03, where the first error is statistical and the second systematic. We also explore B{sup 0}{yields}K{sub S}{sup 0}{pi}{sup 0}{gamma} decays with 1.1<m{sub K{sub S}{sup 0}}{sub {pi}{sup 0}}<1.8 GeV/c{sup 2} and find 59{+-}13 signal events with S{sub K{sub S}{sup 0}}{sub {pi}{sup 0}}{sub {gamma}}=0.9{+-}1.0{+-}0.2more » and C{sub K{sub S}{sup 0}}{sub {pi}{sup 0}}{sub {gamma}}=-1.0{+-}0.5{+-}0.2.« less
  • We measure the time-dependent CP asymmetry in B{sup 0}{yields}K{sub S}{sup 0}{pi}{sup 0}{gamma} decays for two regions of K{sub S}{sup 0}-{pi}{sup 0} invariant mass, m(K{sub S}{sup 0}{pi}{sup 0}), using the final BABAR data set of 467x10{sup 6} BB pairs collected at the PEP-II e{sup +}e{sup -} collider at SLAC. We find 339{+-}24 B{sup 0}{yields}K*{sup 0}{gamma} candidates and measure S{sub K*{gamma}}=-0.03{+-}0.29{+-}0.03 and C{sub K*{gamma}}=-0.14{+-}0.16{+-}0.03. In the range 1.1<m(K{sub S}{sup 0}{pi}{sup 0})<1.8 GeV/c{sup 2} we find 133{+-}20 B{sup 0}{yields}K{sub S}{sup 0}{pi}{sup 0}{gamma} candidates and measure S{sub K{sub S}{sup 0}}{sub {pi}{sup 0}}{sub {gamma}}=-0.78{+-}0.59{+-}0.09 and C{sub K{sub S}{sup 0}}{sub {pi}{sup 0}}{sub {gamma}}=-0.36{+-}0.33{+-}0.04. The uncertainties aremore » statistical and systematic, respectively.« less
  • We study the decays B{sup -}{yields}D{sup 0}{pi}{sup -} and B{sup -}{yields}D{sup 0}K{sup -}, where the D{sup 0} decays into D{sup 0}{pi}{sup 0}, with the D{sup 0} reconstructed in the CP-even (CP+) eigenstates K{sup -}K{sup +} and {pi}{sup -}{pi}{sup +} and in the (non-CP) channels K{sup -}{pi}{sup +}, K{sup -}{pi}{sup +}{pi}{sup +}{pi}{sup -}, and K{sup -}{pi}{sup +}{pi}{sup 0}. Using a sample of about 123x10{sup 6} BB pairs, we measure the ratios of decay rates R{sub non-CP}{sup {identical_to}}(B(B{sup -}{yields}D{sub non-CP}{sup 0}K{sup -})/B(B{sup -}{yields}D{sub non-CP}{sup 0}{pi}{sup -}))=0.0813{+-}= 0.0040(stat){sub -0.0031} {sup +0.0042}(syst), and provide the first measurements of R{sub CP+}{sup {identical_to}}(B(B{sup -}{yields}D{sub CP+}{sup 0}K{supmore » -})/B(B{sup -}{yields}D{sub CP+}{sup 0}{pi}{sup -}))=0.086{+-}0.021(stat){+-}0.007(syst), and of the CP asymmetry A{sub CP+}{sup {identical_to}}(B(B{sup -}{yields}D{sub CP+}{sup 0}K{sup -})-B(B{sup +}{yields}D{sub CP+}{sup 0}K{sup +})/B(B{sup -}{yields}D{sub CP+}{sup 0}K{sup -})+B(= B{sup +}{yields}D{sub CP+}{sup 0}K{sup +}))=-0.10{+-}0.23 (stat){sub -0.04}{sup +0.03}(syst)« less
  • We present measurements of time-dependent CP asymmetries in B{sup 0}{yields}{omega}K{sub S}{sup 0}, f{sub 0}(980)K{sub S}{sup 0}, K{sub S}{sup 0}{pi}{sup 0} and K{sup +}K{sup -}K{sub S}{sup 0} decays based on a sample of 535x10{sup 6} BB pairs collected at the {upsilon}(4S) resonance with the Belle detector at the KEKB energy-asymmetric e{sup +}e{sup -} collider. One neutral B meson is fully reconstructed in one of the specified decay channels, and the flavor of the accompanying B meson is identified from its decay products. CP-violation parameters for each of the decay modes are obtained from the asymmetries in the distributions of the proper-timemore » intervals between the two B decays.« less