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Register a new userNew physics contributions to $bar{B}_s rightarrow pi^0(rho^0 ),eta^{()} $ decays
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Gaber Faisel
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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 $S_{Z} (B_s) simeq -2 S_{SM} (B_s)$.
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We study the decay modes $bar{B}_sto phi pi^0$ and $bar{B}_sto phi rho^0$ within the frameworks of two-Higgs doublet models type-II and typ-III. We adopt in our study Soft Collinear Effective Theory as a framework for the calculation of the amplitudes. We derive the contributions of the charged Higgs mediation to the weak effective Hamiltonian governing the decay processes in both models. Moreover we analyze the effect of the charged Higgs mediation on the Wilson coefficients of the electrowek penguins and on the branching ratios of $bar{B}_sto phi pi^0$ and $bar{B}_sto phi rho^0$ decays. We show that wthin two-Higgs doublet models type-II and type-III the Wilson coefficients corresponding to the electroweak penguins can be enhanced due to the contributions from the charged Higgs mediation leading into enhancement in the branching ratios of $ bar{B}_sto phi pi^0$ and $bar{B}_sto phi rho^0 $ decays. We find that, within two-Higgs doublet models type-II, the enhancement in the branching ratio of $bar{B}_sto phi pi^0$ can not exceed $18%$ with respect to the SM predictions. For the branching ratio of $bar{B}_sto phi rho^0$, we find that the charged Higgs contribution in this case is small where the branching ratio of $bar{B}_sto phi rho^0$ can be enhanced or reduced by about $4% $ with respect to the SM predictions. For the case of the two-Higgs doublet models type-III we show that the branching ratio of $bar{B}_sto phi pi^0$ can be enhanced by about a factor $2$ of its value within two-Higgs doublet models type-II. However no sizable enhancement with respect to the SM predictions can be obtained for both $bar{B}_sto phi pi^0$ and $bar{B}_sto phi rho^0$ decays.
The Dalitz plot distribution of $B^0 rightarrow bar{D}^0 K^+ pi^-$ decays is studied using a data sample corresponding to $3.0rm{fb}^{-1}$ of $pp$ collision data recorded by the LHCb experiment during 2011 and 2012. The data are described by an amplitude model that contains contributions from intermediate $K^*(892)^0$, $K^*(1410)^0$, $K^*_2(1430)^0$ and $D^*_2(2460)^-$ resonances. The model also contains components to describe broad structures, including the $K^*_0(1430)^0$ and $D^*_0(2400)^-$ resonances, in the $Kpi$ S-wave and the $Dpi$ S- and P-waves. The masses and widths of the $D^*_0(2400)^-$ and $D^*_2(2460)^-$ resonances are measured, as are the complex amplitudes and fit fractions for all components included in the amplitude model. The model obtained will be an integral part of a future determination of the angle $gamma$ of the CKM quark mixing matrix using $B^0 rightarrow D K^+ pi^-$ decays.
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.
Proton-proton collision data recorded in 2011 and 2012 by the lhcb experiment, co-rres-pon-ding to an integrated luminosity of 3.0invfb, are a-na-lysed to search for the charmless ${B^0 to rho^0 rho^0}$ decay. More than 600 ${B^0 to (pi^+pi^-)(pi^+pi^-)}$ signal decays are selected and used to perform an amplitude analysis from which the ${B^0 to rho^0 rho^0}$ decay is observed for the first time with 7.1 standard deviations significance. The fraction of ${B^0 to rho^0 rho^0}$ decays yielding a longitudinally polarised final state is measured to be $fL = 0.745^{+0.048}_{-0.058} ({rm stat}) pm 0.034 ({rm syst})$. The ${B^0 to rho^0 rho^0}$ branching fraction, using the ${B^0 to phi K^*(892)^{0}}$ decay as reference, is also reported as ${BF(B^0 to rho^0 rho^0) = (0.94 pm 0.17 ({rm stat}) pm 0.09 ({rm syst}) pm 0.06 ({rm BF})) times 10^{-6}}$.
We perform a quantitative analysis of the $bbbar{b}bar{b}$ tetraquark decays into hidden- and open-bottom mesons and calculate, for the first time, the $bbbar{b}bar{b}$ tetraquark total decay width. On the basis of our results, we propose the $bbbar{b}bar{b} to B^{+} B^{-} (B^0 bar{B}^0) (B_s^0 bar{B}_s^0) to l^{+} l^{-}+text{X}$ decays as the most suitable channels to observe the $bbbar{b}bar{b}$ tetraquark states, since the calculated two-lepton cross section upper limit, $simeq 39 $ fb, is so large as to be potentially detectable with the 2018 LHCb sensitivity, paving the way to the observation of the $bbbar{b}bar{b}$ tetraquark in the future LHCb upgrade. The $4mu$ signal for the ground state, $J^{PC}=0^{++}$, is likely to be too small even for the upgraded LHCb, but it may not be hopeless for the $J^{PC}=2^{++}$ fully-bottom state.
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