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Register a new userChiral dynamics and S-wave contributions in $bar B^0/D^0 to pi^{pm}eta l^{mp} u$ decays
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In this work, we analyze the semi-leptonic decays $bar B^0/D^0 to (a_0(980)^{pm}topi^{pm}eta) l^{mp} u$ 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 $a_0(980)$, we use a scalar form factor to describe the final-state interaction between the $pieta$ mesons, which was previously calculated within unitarized Chiral Perturbation Theory. The result for the decay branching fraction of the $D^0$ decay is in good agreement with that measured by the BESIII Collaboration, while the branching fraction of the $bar B^0$ decay can be tested in future experiments.
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The decay modes $bar{B}_s rightarrow pi^0(rho^0 ),eta^{()} $ are dominated by electroweak penguins that are small in the standard model. In this work we investigate the contributions to these penguins from a model with an additional $U(1)$ gauge symmetry and show there effects on the branching ratios of $bar{B}_s rightarrow pi^0(rho^0 ),eta^{()} $. In a scenario of the model, where $Z^prime$ couplings to the left-handed quarks vanish, we show that the maximum enhancement occurs in the branching ratio of $bar B^0_sto ,pi^0,eta$ where it can reach $6$ times the SM prediction. On the other hand, in a scenario of the model where $Z^prime$ couplings to both left-handed and right-handed quarks do not vanish, we find that $Z^prime$ contributions can enhance the branching ratio of $B^0_sto,rho^0,eta$ up to one order of magnitude comparing to the SM prediction for several sets of the parameter space where both $ Delta M_{B_s}$ and $S_{psiphi}$ constraints are satisfied. This kind of enhancement occurs for a rather fine-tuned point where $ Delta M_{B_s}$ constraint on $mid S_{SM} (B_s) + S_{Z} (B_s)mid $ is fulfilled by overcompensating the SM via $S_{Z} (B_s) simeq -2 S_{SM} (B_s)$.
The decay mode $B^{0}_{s} to D^{mp}_{s} K^{pm} $ allows for one of the theoretically cleanest measurements of the CKM angle $gamma$ through the study of time-dependent $ensuremath{CP}xspace$ violation. This paper reports a measurement of its branching fraction relative to the Cabibbo-favoured mode $B^{0}_{s} to D^{-}_{s} pi^{+}$ based on a data sample of 0.37 fb$^{-1}$ proton-proton collisions at $sqrt{s} = 7$ TeV collected in 2011 with the LHCb detector. In addition, the ratio of $ensuremath{mathrm{B}}xspace$ meson production fractions $ensuremath{f_s/f_d}$, determined from semileptonic decays, together with the known branching fraction of the control channel $B^{0} to D^{-} pi^{+}$, is used to perform an absolute measurement of the branching fractions: $B (B^0_s to D^-_s pi^+) ;= (2.95 pm 0.05 pm 0.17^{,+,0.18}_{,-,0.22}) times 10^{-3}$, $B (B^0_s to D^mp_s K^pm) = (1.90 pm 0.12 pm 0.13^{,+,0.12}_{,-,0.14}) times 10^{-4},$, where the first uncertainty is statistical, the second the experimental systematic uncertainty, and the third the uncertainty due to $f_s/f_d$.
The first untagged decay-time-integrated amplitude analysis of $B^{0}_{s} rightarrow K^{0}_{textrm{S}} K^{pm}pi^{mp}$ decays is performed using a sample corresponding to $3.0,$fb$^{-1}$ of $pp$ collision data recorded with the LHCb detector during 2011 and 2012. The data are described with an amplitude model that contains contributions from the intermediate resonances $K^{*}(892)^{0,+}$, $K^*_2(1430)^{0,+}$ and $K^*_0(1430)^{0,+}$, and their charge conjugates. Measurements of the branching fractions of the decay modes $B^{0}_{s} rightarrow K^{*}(892)^{pm}K^{mp}$ and $B^{0}_{s} rightarrow K^{*}(892)^{0}kern 0.2emoverline{kern -0.2em K}{}^{0}, kern 0.2emoverline{kern -0.2em K}{}^{*}(892)^{0}K^{0}$ are in agreement with, and more precise than, previous results. The decays $B^{0}_{s} rightarrow K^*_0(1430)^{pm} K^{mp}$ and $B^{0}_{s} rightarrow K^{*}_{0}(1430)^{0}kern 0.2emoverline{kern -0.2em K}{}^{0}, kern 0.2emoverline{kern -0.2em K}{}^{*}_{0}(1430)^{0}K^{0}$ are observed for the first time, each with significance over 10 standard deviations.
Amplitude models are constructed to describe the resonance structure of ${D^{0}to K^{-}pi^{+}pi^{+}pi^{-}}$ and ${D^{0} to K^{+}pi^{-}pi^{-}pi^{+}}$ decays using $pp$ collision data collected at centre-of-mass energies of 7 and 8 TeV with the LHCb experiment, corresponding to an integrated luminosity of $3.0mathrm{fb}^{-1}$. The largest contributions to both decay amplitudes are found to come from axial resonances, with decay modes $D^{0} to a_1(1260)^{+} K^{-}$ and $D^{0} to K_1(1270/1400)^{+} pi^{-}$ being prominent in ${D^{0}to K^{-}pi^{+}pi^{+}pi^{-}}$ and $D^{0}to K^{+}pi^{-}pi^{-}pi^{+}$, respectively. Precise measurements of the lineshape parameters and couplings of the $a_1(1260)^{+}$, $K_1(1270)^{-}$ and $K(1460)^{-}$ resonances are made, and a quasi model-independent study of the $K(1460)^{-}$ resonance is performed. The coherence factor of the decays is calculated from the amplitude models to be $R_{K3pi} = 0.459pm 0.010,(mathrm{stat}) pm 0.012,(mathrm{syst}) pm 0.020,(mathrm{model})$, which is consistent with direct measurements. These models will be useful in future measurements of the unitary-triangle angle $gamma$ and studies of charm mixing and $C!P$ violation.
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