Study the $$B^{0}_{(s)}$$ decays into $$\phi $$ and a scalar or vector meson

In the present work, we investigate the decays of $$B^{0}_{(s)} \rightarrow \phi \pi ^{+}\pi ^{-}$$ B ( s ) 0 → ϕ π + π - with the final state interaction based on the chiral unitary approach. In the final state interaction of the $$\pi ^+\pi ^-$$ π + π - with its coupled channels, we study the effects of the $$\eta \eta $$ η η channel in the two-body interaction for the reproduction of the $$f_{0}(980)$$ f 0 ( 980 ) state, where its contribution to the $$f_{0}(980)$$ f 0 ( 980 ) state can be ignored. Our results for the $$\pi ^+\pi ^-$$ π + π - invariant mass distributions of the decay $$B^{0}_{s} \rightarrow \phi \pi ^{+}\pi ^{-}$$ B s 0 → ϕ π + π - describe the experimental data up to 1 GeV well, with the resonance contributions from the $$f_{0}(980)$$ f 0 ( 980 ) and $$\rho $$ ρ . For the predicted invariant mass distributions of the $$B^{0} \rightarrow \phi \pi ^{+}\pi ^{-}$$ B 0 → ϕ π + π - decay, we find that the contributions from the $$f_{0}(500)$$ f 0 ( 500 ) are significant, but not from the $$f_{0}(980)$$ f 0 ( 980 ) state. With some experimental branching ratios to determine the production vertex factors, we make predictions for the branching ratios of the other decay channels, including the vector mesons, in the $$B^0_{(s)}$$ B ( s ) 0 decays, some of which are consistent with the experimental measurements within the uncertainties.

Weak decays of bottom-charm baryons: $$\mathcal {B}_{bc}\rightarrow \mathcal {B}_bP$$

After the discovery of the double-charm baryon $$\Xi _{cc}^{++}$$ Ξ cc + + by LHCb, one of the most important topics is to search for the bottom-charm baryons which contain a b quark, a c quark and a light quark. In this work, we study the two-body non-leptonic weak decays of a bottom-charm baryon into a spin-1/2 bottomed baryon and a light pseudoscalar meson with the short-distance contributions calculated under the factorization hypothesis and the long-distance contributions considering the final-state-interaction effects. The branching fractions of all fifty-seven decay channels are estimated. The results indicate that $$\Xi _{bc}^+\rightarrow \Xi _b^0\pi ^+$$ Ξ bc + → Ξ b 0 π + , $$\Xi _{bc}^{0}\rightarrow \Xi _{b}^{-}\pi ^+$$ Ξ bc 0 → Ξ b - π + and $$\Omega _{bc}^0\rightarrow \Omega _b^-\pi ^+$$ Ω bc 0 → Ω b - π + decay modes have relatively large decay rates and thus could be used to experimentally search for the bottom-charm baryons. The topological diagrams and the SU(3) symmetry of bottom-charm baryon decays are discussed.

Chiral dynamics and S-wave contributions in $${\bar{B}}^0/D^0 \rightarrow \pi ^{\pm }\eta \ l^{\mp } \nu $$ decays

In this work, we analyze the semi-leptonic decays $$\bar{B}^0/D^0 \rightarrow (a_0(980)^{\pm }\rightarrow \pi ^{\pm }\eta ) l^{\mp } \nu $$ B ¯ 0 / D 0 → ( a 0 ( 980 ) ± → π ± η ) l ∓ ν within light-cone sum rules. The two and three-body light-cone distribution amplitudes (LCDAs) of the B meson and the only available two-body LCDA of the D meson are used. To include the finite-width effect of the $$a_0(980)$$ a 0 ( 980 ) , we use a scalar form factor to describe the final-state interaction between the $$\pi \eta $$ π η mesons, which was previously calculated within unitarized Chiral Perturbation Theory. The result for the decay branching fraction of the $$D^0$$ D 0 decay is in good agreement with that measured by the BESIII Collaboration, while the branching fraction of the $${\bar{B}}^0$$ B ¯ 0 decay can be tested in future experiments.

Combined theoretical study of the $$D^+ \rightarrow \pi ^+ \eta \eta $$ and $$D^+ \rightarrow \pi ^+ \pi ^0 \eta $$ reactions

We study the $$D^+ \rightarrow \pi ^+ \eta \eta $$ D + → π + η η and $$D^+ \rightarrow \pi ^+ \pi ^0 \eta $$ D + → π + π 0 η reactions, which are single Cabibbo suppressed and can proceed both through internal and external emission. The primary mechanisms at quark level are considered, followed by hadronization to produce three mesons in the $$D^+$$ D + decay, and after that the final state interaction of these mesons leads to the production of the $$a_0(980)$$ a 0 ( 980 ) resonance, seen in the $$\pi ^+ \eta $$ π + η , $$\pi ^0 \eta $$ π 0 η mass distributions. The theory has three unknown parameters to determine the shape of the distributions and the ratio between the $$D^+ \rightarrow \pi ^+ \eta \eta $$ D + → π + η η and $$D^+ \rightarrow \pi ^+ \pi ^0 \eta $$ D + → π + π 0 η rates. This ratio restricts much the sets of parameters but there is still much freedom leading to different shapes in the mass distributions. We call for a measurement of these mass distributions that will settle the reaction mechanism, while at the same time provide relevant information on the way that the $$a_0(980)$$ a 0 ( 980 ) resonance is produced in the reactions.