Cp Asymmetries in Nonleptonic Decay of Neutral B Mesons for Three and Four Generations

Abstract

We investigate the effects of CP violation in nonleptonic decays of neutral B mesons (Bd, Bs) in the Kobayashi-Maskawa model through the quark exchange diagram in terms of the Wolfenstein matrix. In our calculation, we use the new data of mixing parameter xd= 0.70±0.13 which is derived from ARGUS and CLEO measurements and the new data on the branching ratio for Bd meson. We obtain the results that CP violating asymmetries for Bd→D+D−, π+π− and K+K− reach about 50% and the number of [Formula: see text] quark pairs needed to detect the asymmetry is O(106~107) at 3σ level, and the asymmetries for [Formula: see text], D−π+, D0π0 and D+π− reach the order of 20% and the number of [Formula: see text] pairs is O(108). Therefore, we may conclude that the CP violation for these decay modes is possibly observable at the present stage. The effects of fourth generation quarks on CP violation are also studied.

Effects of theK+→π+νν¯Hattori1, Hasuike2, Wakaizumi3 1999Phys. Rev. DSelf Cite232160View full textAdd to dashboardCite

“…In the Standard Model [29], the quantity C f takes a positive sign as 0.18 ≤ C f ≤ 0.37 for B d → J/ψK S , resulting from the phase range of 0 < φ 1 < π, which is constrained from the positive sign of the CPviolating parameter ε K . However, in the four-generation model [7], C f can take also a negative sign as −0.38 ≤ C f ≤ 0.40, since the phase φ 1 takes the whole range of 0 < φ 1 < 2π due to the occurence of the two more new phases φ 2 and φ 3 .…”

“…In this work, we analyze the new branching ratio of K + → π + ν ν in the fourgeneration model [5][6] [7] under the expectation that the above-mentioned factor 4-6 of the measured value relative to the Standard Model predictions may imply the existence of a fourth generation with roughly the same mixing as for the third generation. We will investigate various possible mixings for the fourth generation by imposing the constraints of K + → π + ν ν and other processes of K L − K S mass difference ∆m K , CP-violating parameter ε K , B d − Bd mixing, B s − Bs mixing, D 0 − D0 mixing, B(K L → π 0 ν ν) and B(K L → µμ), and we will study its effects on the D 0 − D0 mixing and B(K L → π 0 ν ν), of which only the upper bounds are experimentally known, CP violation in neutral B meson decays and the unitarity triangle.…”

New Physics and CP Angles Measurement at B Factory

“…New physics can affect the determination of the unitarity triangle through (i) B 0 -B 0 mixing as in the case of SUSY standard models [3] , (ii) b decay as in SU(2) L ×SU(2) R ×U(1) models [4] or (iii) deformation of KM matrix as in 4 generation models [5] or extra vector-like quark models [6]. It has once said that new physics can be explored by checking whether the sum of the three CP angles becomes π or not [2].…”

CP Violation in B Physics

“…The results of a survey of models beyond the Standard Model(48) are summarized in Figure4. Models beyond the Standard Model that have been studied include fo ur quark generations(49)(50)(51)(52), a multi scalar model with natural flavor conservation (NFC) and with explicit or spon taneous CP violation (SCPV)(53), Z-mediated flavor-changing neutral currents (FCNC)(54,55), left-right symmetry (LRS)(56 , 57), super symmetry (SUSY) (58), and "real superweak" models(59). Many of these models allow substantial deviations fr om the Standard Model predictions.Sume relations among the asymmetries do not depend on certain assumptions and thus may hold beyond the Standard Model or, con versely, if they are violated can help pinpoint which ingredients must be added to the Standard Model(19,47,48).…”