Probing new physics in class-I B-meson decays into heavy-light final states

Abstract

With updated experimental data and improved theoretical calculations, several significant deviations are being observed between the Standard Model predictions and the experimental measurements of the branching ratios of $$ {\overline{B}}_{(s)}^0\to {D}_{(s)}^{\left(\ast \right)+}{L}^{-} $$ B ¯ s 0 → D s ∗ + L − decays, where L is a light meson from the set {π, ρ, K(∗)}. Especially for the two channels $$ {\overline{B}}^0\to {D}^{+}{K}^{-} $$ B ¯ 0 → D + K − and $$ {\overline{B}}_s^0\to {D}_s^{+}{\pi}^{-} $$ B ¯ s 0 → D s + π − , both of which are free of the weak annihilation contribution, the deviations observed can even reach 4–5σ. Here we exploit possible new-physics effects in these class-I non-leptonic B-meson decays within the framework of QCD factorization. Firstly, we perform a model-independent analysis of the effects from twenty linearly independent four-quark operators that can contribute, either directly or through operator mixing, to the quark-level b →$$ c\overline{u}d(s) $$ c u ¯ d s transitions. It is found that, under the combined constraints from the current experimental data, the deviations observed could be well explained at the 1σ level by the new-physics four-quark operators with γμ(1 − γ5) ⨂ γμ(1 − γ5) structure, and also at the 2σ level by the operators with (1 + γ5) ⨂ (1 − γ5) and (1 + γ5) ⨂ (1 + γ5) structures. However, the new-physics four-quark operators with other Dirac structures fail to provide a consistent interpretation, even at the 2σ level. Then, as two specific examples of model-dependent considerations, we discuss the case where the new-physics four-quark operators are generated by either a colorless charged gauge boson or a colorless charged scalar, with their masses fixed both at the 1 TeV. Constraints on the effective coefficients describing the couplings of these mediators to the relevant quarks are obtained by fitting to the current experimental data.

QED factorization of non-leptonic B decays

“…(s) → D + (s) π − [5][6][7]. Such decays are dominated by colour-allowed tree topologies described by the topological tree-amplitude a 1 (D + L − ).…”

Revisiting rescattering contributions to $$ \overline{B} $$(s) → $$ {D}_{(s)}^{\left(\ast \right)}M $$ decays

“…In this appendix we present some details of the fit results in section 3.3. Figures 6,7,8,and 9 show the one-dimensional and two-dimensional probability distributions of the parameters in the fit (ii), which uses all the available experimental data for B → DP , B → D * P , B → DV with the solution 1 in eq. (2.20), and B → DV with the solution 2 in eq.…”

“…The probability in the low a 1 (m b ) region is suppressed in the fit (ii) as presented by the red-colored distribution. It is found that the preferred regions of a 1 (m b ) differs from the QCDF prediction by more than 2σ in B → DP and D * P , and 1σ in B → DV .The NP interpretations of the deviation in a 1 (m b ) are scrutinized in refs [5,7,9,66]…”

“…The FSI effects in heavy meson decays were explored first for the charmed meson decays in ref [19]. using QCD sum rules 7. It is assumed that the SU(3) flavor symmetry holds between the B → D ( * ) and Bs → D ( * ) s form factors as suggested in the result of refs [6,38]…”

Updated search for $$ {B}_c^{+} $$ decays to two charm mesons

“…Final-state interactions may result in an enhancement of B + c → D + ( ) D 0 decay rates [15]. Moreover, contributions from physics beyond the Standard Model could potentially affect fully hadronic B decays [16][17][18].…”