Search

Many exclusive $c\to d/s\ell^+\nu_\ell~(\ell=e,\mu,\tau)$ transitions have been well measured, and they can be used to test the theoretical calculations. Motivated by this, we study the $D\to P/V/S\ell^+\nu_\ell$ decays induced by the $c\to d/s\ell^+\nu_\ell$ transitions with the SU(3) flavor symmetry approach, where $P$ denotes the pseudoscalar meson, $V$ denotes the vector meson, and $S$ denotes the scalar meson with a mass below $1$ $GeV$. The different decay amplitudes of the $D\to P\ell^+\nu_\ell$, $D\to V\ell^+\nu_\ell$ or $D\to S\ell^+\nu_\ell$ decays can be related by using the SU(3) flavor symmetry and by considering the SU(3) flavor breaking. Using the present data of $D\to P/V/S\ell^+\nu_\ell$, we predict the not yet measured or not yet well measured processes in the $D\to P/V/S\ell^+\nu_\ell$ decays. We find that the SU(3) flavor symmetry approach works well in the semileptonic $D \to P/V\ell^+\nu_\ell$ decays. For the $D \to S\ell^+\nu_\ell$ decays, only the decay $D^+_s\to f_0(980)e^+\nu_e$ has been measured, the branching ratios of the $D^+_s\to f_0(980)e^+\nu_e$ and $D\to S(S\to P_1P_2)\ell^+\nu_\ell$ decays are used to constrain the nonperturbative parameters and then predict not yet measured $D \to S\ell^+\nu_\ell$ decays, in addition, the two quark and the four quark scenarios for the light scalar mesons are analyzed. The SU(3) flavor symmetry predictions of the $D \to S\ell^+\nu_\ell$ decays need to be further tested, and our predictions of the $D \to S\ell^+\nu_\ell$ decays are useful for probing the structure of light scalar mesons. Our results in this work could be used to test the SU(3) flavor symmetry approach in the semileptonic $D$ decays by the future experiments at BESIII, LHCb and BelleII., Comment: 23 pages, 4 figures

Recently, several hints of lepton non-universality have been observed in the semileptonic B meson decays in terms of both in the neutral current ($b\to s l \bar{l}$) and charged current ($b\to c l \bar{\nu_{l}}$) transitions. Motivated by these inspiring results, we perform the analysis of the baryon decays ${\Sigma_b}\to \Sigma_c l \bar{\nu_{l}}$ and $\Omega_b\to \Omega_c l \bar{\nu_{l}} (l=e,\mu,\tau)$ which are mediated by $ b \to c l \bar{\nu_{l}}$ transitions at the quark level, to scrutinize the nature of new physics (NP) in the model independent method. We first use the experimental measurements of $\mathcal{B}( B\to D^{(*)} l\bar{\nu_{l}})$, ${\rm R}_{D^{(*)}}$ and ${\rm R}_{J/\psi}$ to constrain the NP coupling parameters in a variety of scenarios. Using the constrained NP coupling parameters, we report numerical results on various observables related to the processes ${\Sigma_b}\to \Sigma_c l \bar{\nu_{l}}$ and $\Omega_b\to \Omega_c l \bar{\nu_{l}}$, such as the branching ratios, the ratio of branching fractions, the lepton side forward-backward asymmetries, the hadron and lepton longitudinal polarization asymmetries and the convexity parameter. We also provide the $q^2$ dependency of these observables and we hope that the corresponding numerical results in this work will be testified by future experiments., Comment: 11 pages 4 figures Accept by PRD

Leptoquarks have been suggested to solve a variety of discrepancies between the expected and observed phenomenon. In this paper, we investigate the effect of scalar leptoquarks on the lepton flavor violating B meson rare decays which involve the quark level transition $\bar{b} \to \bar{s} \ell^-_i \ell^+_j(i \neq j)$. The leptoquark parameter space is constrained by using the recently measured upper limits on the $\mathcal{B}(B_s^0 \to \ell^-_i \ell^+_j)$ and $\mathcal{B}(B \to K^{(*)}\ell^-_i \ell^+_j)$. Using such constrained leptoquark parameter space, some relevant physical quantities are also predicted and we find that the constrained New Physics parameters in the leptoquark model have very obvious effects on the relevant physical quantities in this paper. With future measurements of observable in $B \to K^{(*)}\ell^-_i \ell^+_j$ decays at the LHCb, more and more differentiated from the other NP explanations could be tested., Comment: 16 pages;5 figures Appendix; publication in International Journal of Theoretical Physics

We study the rare decays $D^+\to \pi^{+}\ell^+\ell^-$, $D^+_s\to K^{+}\ell^+\ell^-$ and $D^0\to \ell^+\ell^-(\ell=e,\mu)$ in the minimal supersymmetic standard model with and without R-parity. Using the strong constraints on relevant supersymmetric parameters from $D^0-\bar{D}^0$ mixing and $K^+\to \pi^+\nu\bar{\nu}$ decay, we examine constrained supersymmetry contributions to relevant branching ratios, direct CP violations and ratios of $D^+_{(s)}\to \pi(K)^{+}\mu^+\mu^-$ and $D^+_{(s)}\to \pi(K)^{+}e^+e^-$ decay rates. We find that both R-parity conserving LR as well as RL mass insertions and R-parity violating squark exchange couplings have huge effects on the direct CP violations of $D^+_{(s)}\to \pi(K)^{+}\ell^+\ell^-$, moreover, the constrained LR and RL mass insertions still have obvious effects on the ratios of $D^+_{(s)}\to \pi(K)^{+}\mu^+\mu^-$ and $D^+_{(s)}\to \pi(K)^{+}e^+e^-$ decay rates. The direct CP asymmetries and the ratios of $D^+_{(s)}\to \pi(K)^{+}\mu^+\mu^-$ and $D^+_{(s)}\to \pi(K)^{+}e^+e^-$ decay rates are very sensitive to both moduli and phases of relevant supersymmetric parameters. In addition, the differential direct CP asymmetries of $D^+_{(s)}\to \pi(K)^{+}\ell^+\ell^-$ are studied in detail., Comment: 18 pages, 9 figures

A lot of branching ratios of the exclusive $c \to d/s\ell\nu_\ell$ ($\ell=e,\mu$) decays have been quite accurately measured by CLEO-c, BELLE, BABAR, BES(I,II,III), ALEPH and MARKIII collaborations. We probe the R-parity violating supersymmetric effects in the exclusive $c \to d/s\ell\nu_\ell$ decays. From the latest experimental measurements, we obtain new upper limits on the relevant R-parity violating coupling parameters within the decays, and many upper limits are obtained for the first time. Using the constrained new parameter spaces, we predict the R-parity violating effects on the observables, which have not been measured or have not been well measured yet. We find that the R-parity violating effects due to slepton exchange could be large on the branching ratios of $D_{d/s}\to e\nu_e$ decays and the normalized forward-backward asymmetries of $D_{u/d}\to \pi/K \ell\nu_\ell$ as well as $D_s\to K \ell\nu_\ell$ decays, and all branching ratios of the relevant semileptonic $D$ decays are sensitive to squark exchange couplings. Our results in this work could be used to probe new physics effects in the leptonic decays as well as the semileptonic decays, and will correlate with searches for direct supersymmetric signals at LHC and BESIII., Comment: 26 pages, 13 figures