TY - JOUR
T1 - Small amplitude effects in B0→D+D- and related decays
AU - Gronau, Michael
AU - Rosner, Jonathan L.
AU - Pirjol, Dan
PY - 2008/8/19
Y1 - 2008/8/19
N2 - Intrigued by a recent Belle result for a large direct CP asymmetry in B0→D+D-, we study the effects of a b̄→ūud̄ quark transition by combining the asymmetry information with rates and asymmetries in isospin-related decays. Arguing for a hierarchy among several contributions to these decays, including an exchange amplitude which we estimate, we present tests for factorization of the leading terms, and obtain an upper bound on the ratio of b̄→ūud̄ and b̄→c̄cd̄ amplitudes. We prove an approximate ΔI=1/2 amplitude relation for B→DD̄, and an approximate equality between CP asymmetries in B0→D+D- and B+→D+D̄0. Violations of these relations by Belle measurements, at 1.8σ and 3.6σ respectively, if confirmed, would indicate a possible new physics contribution in b̄→ūud̄. Applying flavor SU(3), we extend this study to a total of ten processes, including ΔS=0 decays involving final Ds and initial Bs mesons, and ΔS=1 decays of B and Bs mesons into pairs of charmed pseudoscalar mesons. The decays Bs→DD̄ provide useful information about a small exchange amplitude, responsible for a decay rate difference between B+→D+D̄0 and B0→D+D-. A method for determining the weak phase γ, based on CP asymmetries in B0(t)→D+D- and the decay rate for Bs→Ds+Ds- or B+(0)→Ds+D̄0(D-), is shown to involve high sensitivity to SU(3) breaking.
AB - Intrigued by a recent Belle result for a large direct CP asymmetry in B0→D+D-, we study the effects of a b̄→ūud̄ quark transition by combining the asymmetry information with rates and asymmetries in isospin-related decays. Arguing for a hierarchy among several contributions to these decays, including an exchange amplitude which we estimate, we present tests for factorization of the leading terms, and obtain an upper bound on the ratio of b̄→ūud̄ and b̄→c̄cd̄ amplitudes. We prove an approximate ΔI=1/2 amplitude relation for B→DD̄, and an approximate equality between CP asymmetries in B0→D+D- and B+→D+D̄0. Violations of these relations by Belle measurements, at 1.8σ and 3.6σ respectively, if confirmed, would indicate a possible new physics contribution in b̄→ūud̄. Applying flavor SU(3), we extend this study to a total of ten processes, including ΔS=0 decays involving final Ds and initial Bs mesons, and ΔS=1 decays of B and Bs mesons into pairs of charmed pseudoscalar mesons. The decays Bs→DD̄ provide useful information about a small exchange amplitude, responsible for a decay rate difference between B+→D+D̄0 and B0→D+D-. A method for determining the weak phase γ, based on CP asymmetries in B0(t)→D+D- and the decay rate for Bs→Ds+Ds- or B+(0)→Ds+D̄0(D-), is shown to involve high sensitivity to SU(3) breaking.
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U2 - 10.1103/PhysRevD.78.033011
DO - 10.1103/PhysRevD.78.033011
M3 - Article
AN - SCOPUS:50449088815
SN - 1550-7998
VL - 78
JO - Physical Review D - Particles, Fields, Gravitation and Cosmology
JF - Physical Review D - Particles, Fields, Gravitation and Cosmology
IS - 3
M1 - 033011
ER -