Inclusive B decays as a QCD lab

Abstract

Phenomenological models of heavy flavour decays differ significantly in their predictions of global features of B c decays, like the B c lifetime or the relative weight of c → s and b → c transitions. The 1/m Q expansion which is directly based on QCD allows predictions on the pattern to be expected, namely τ (B c ) to lie well below 1 psec with c → s dominating over b → c and a reduced semileptonic branching ratio. Due to interference effects one also predicts a lower charm content in the final states of B c decays than naively anticipated. The numerical aspect of the predictions, however, has to be viewed with considerable caution since one cannot expect the 1/m c expansion to converge readily for ∆C = 1 transitions.

CALCULATION OF THE Bc LEPTONIC DECAY CONSTANT USING THE SHIFTED N-EXPANSION METHOD

“…−0.16 ± 0.03 ps confirmed the theoretical predic-tions regarding various B c meson properties, spectroscopy, production and decay channels [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18].…”

“…The calculation of the B c leptonic decay constant f Bc can be carried out either using QCD-based methods, such as lattice QCD [41], QCD sum rules [42][43][44][45], or adopting some constituent quark models [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. So far, lattice QCD has only been employed to calculate the B c purely leptonic width.…”

“…As the QCD sum rules, the B c leptonic constant, as well as the matrix elements relevant for the semileptonic decays were computed. Moreover, the leptonic constant has also been calculated by using the nonrelativistic (NR) potential model [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18].…”

“…In this study, we have considered the quarkonium potential models, which are usually used in the literature [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][59][60][61][62][63][64], in calculating the B c leptonic constant based on the NR potential model, (cf. e.g.…”

Signature of lepton flavor universality violation in Bs→Dsτν semileptonic decays

“…[38] that the lifetime of the B c meson puts severe constraint on various NP couplings. Based on various SM calculations [63][64][65] of the B c lifetime, it is found that BðB c → τνÞ cannot be more than 5%. However, this can be relaxed up to 30% depending on the input parameters that are used in the SM calculation.…”