Global analysis of charmless B decays into two vector mesons in soft-collinear effective theory

Abstract

Under the framework of soft-collinear effective theory, we analyze the charmless B → V V decays in a global way at leading power in 1/m b and leading order in α s with V denoting a light vector meson. In the flavor SU(3) symmetry, decay amplitudes for the 28 decay modes are expressed in terms of 8 nonperturbative parameters. With 35 experimental results, we fit these 8 nonperturbative parameters. Annihilation contributions are neglected due to power suppression in the m b → ∞ limit, so we include in the fit the nonperturbative charm penguins, which will play an important role in understanding the direct CP asymmetries. Charming penguins are also responsible for the large transverse polarizations of penguin-dominated and color-suppressed decays. With the best fitted parameters, we calculate all possible physical observables of 28 decay modes, including branching fractions, direct CP asymmetries, and the complete set of polarization observables. Most of our results are compatible with the present experimental data when available, while the others can be examined on the ongoing LHCb experiment and the forthcoming Belle-II experiment. Moreover, the agreements and differences with results in QCD factorization and perturbative QCD approach are also discussed. A few observables are suggested to discriminate these different approaches. * Weak decays of B mesons can provide us not only an interesting avenue to understand the CP violation and the quark flavor mixing in the standard model (SM), but also a powerful means to probe new physics effects beyond the SM [1,2]. Experimentally, the B meson weak decays have been extensively investigated in the past decades at both e + e − colliders (B-factories) at SLAC and KEK, and hadronic environments such as Tevatron. The experimental results obtained by Babar, Belle, D0 and CDF collaborations have reached an unprecedented precision [3]. In recent years, with the running of LHC at CERN, the LHCb experiment has become the main player of the bottom quark. To date a large amount of bottom meson and baryon events has been accumulated, and a number of results related to non-leptonic decays have been released and more analyses are ongoing [4]. In addition, the forthcoming Belle-II experiment will further improve the experimental precision significantly [5].With the plethora of precise experimental data on nonleptonic decays at hand, theoretical predictions at the same level of accuracy are very much desired. However, for dealing with the hadronic B decays theoretically, the major obstacle is to reliably evaluate the hadronic matrix elements of local operators between the initial and final hadronic states, especially due to the nontrivial QCD dynamics involved. In the past two decades, three major QCD-inspired approaches had been proposed to calculate the charmless non-leptonic B decays, namely, QCD factorization (QCDF) [6], perturbative QCD (PQCD) [7], and soft-collinear effective theory (SCET) [8]. A prominent difference among them resides in the treatment of dynamical degrees of freed...

Branching Ratio and CP Violation in B s 0 ¯ → ϕϕ Decay in the Framework of QCD Factorization

“…We find that direct CP violation (A dir CP ), CP violation in mixing (A mix CP ) and CP violation due to interference (A ∆Γ CP ) are 0.00355 ± 0.00152, −0.00629 ± 0.03119 and 0.99997 ± 0.00019, respectively. We find that the reported results are consistent with other available predictions and experimental observation [5,[8][9][10]18,20,21,[23][24][25].…”

“…The study of the CP violation in the B s system with the benefit of faster oscillation offers an excellent opportunity to detect the possible deviations from SM predictions and may lead to a new physics beyond the SM. Many authors have studied the decays of B s → PP, PV, VV [3,5,[12][13][14][15][16][17][18][19][20][21][22][23][24], with V being a light vector meson and P being a pseudoscalar meson. The decay of B s → VV reveals more dynamics than B s → PV or B s → PP.…”

“…In order to get a clear idea of CP violation, one needs to know the exact BR of the decay modes which motivates us to make an analytic calculation of the BR(B 0 s → φφ). The analytic calculation of the BR of B s → VV decays is achieved by many approaches as Quantum Chromodynamics Factorization (QCDF) [5,18], the Perturbative QCD (PQCD) [20,21], the Soft-Collinear Effective Theory (SCET) [22,23] and Factorization-Assisted Topological amplitude (FAT) [24].…”

Unification of flavor SU(3) analyses of heavy Hadron weak decays

“…In Ref. [36], the authors have adopted the dynamical analysis in the SCET and performed a flavor SU(3) fit of B → V V decays. On the other hand, recent dynamical improvements exist in Refs.…”

Four-body decays B(s) → (Kπ)S/P(Kπ)S/P in the perturbative QCD approach

“…Subsequently, a flavor-tagged decay-time-dependent amplitude study of this mode in a K ± π ∓ mass window extending from 750 to 1600 MeV was presented [29], where not only the K * andK * resonances, but also several scalar, vector and tensor components in the Kπ system were examined. More recently, the LHCb performed a combined amplitude analysis for the B 0 s → (K + π − )(K − π + ) and B 0 → (K + π − )(K − π + ) decays, which are related by the U -spin symmetry, and found different polarization patterns: the latter is dominated by the longitudinal polarization, while the low longitudinal polarization contribution to the former deviates from theoretical expectations in the SM [32][33][34][35][36][37][38].…”