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A lot of branching ratios of the exclusive c → d/sℓν ℓ (ℓ = e, µ) 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 → d/sℓν ℓ 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 → eν e decays and the normalized forward-backward asymmetries of D u/d → π/Kℓν ℓ as well as D s → Kℓν ℓ 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. The c → d/sℓν ℓ transitions have played a central role for the most precise measurements of CKM matrix elements V cd and V cs for a long time. These rare charmed decays also have received a lot of attention, since they are very promising for investigating the standard model (SM) and searching for new physics (NP) beyond it. The 26 charmed decays, , are dominated by c → d/sℓν ℓ transitions. Many collaborations, such as BSEIII [1-4], CLEO-c [5-12] and BELLE [13, 14], BABAR [15, 16], BESII [17], BES [18-21], ALEPH [22] and MARK-III [23], have studied the exclusive c → d/sℓν ℓ decays, and a lot of branching ratios have been quite accurately measured by them. Present experimental measurements are in good agreement with the SM predictions, and they give us an opportunity to disprove NP or find bounds over NP models beyond the SM.The exclusive c → d/sℓν ℓ decays have been studied extensively in the SM and its various extensions (see for instance ). In the present study, we will analyze these decays in supersymmetry (SUSY) without R-parity. We will obtain eight new upper limits on the relevant supersynmmetric coupling parameters that satisfy all of the experimental data from the relevant charmed decays. Using the constrained new parameter spaces, we will predict the R-parity violating (RPV) effects on the branching ratios, the differential branching ratios and the normalized forward-backward asymmetries of charged leptons. Our results imply that the constrained RPV couplings due to slepton exchange have great effects on B(D d/s → eν e ), and they could obviously enhance the allowed ranges of A F B (D → P ℓν ℓ ). Nevertheless, the RPV contributions due to squark exchange couplings could enhance the predictions of all semileptonic branching ratios, which are very sensitive to the relevent RPV coupling products. This paper is schemed as follows: In secti...

In recent years, the experimental results about the ratio of the branching ratios $$R_{D^{(*)}}$$ R D ( ∗ ) and $$R_{K^{(*)}}$$ R K ( ∗ ) , which are in the semileptonic $$b\rightarrow c l \bar{\nu }_{l}$$ b → c l ν ¯ l and $$b\rightarrow s l^+l^-$$ b → s l + l - decays, have been observed to deviate from the Standard Model prediction by $$1.4\sigma $$ 1.4 σ , $$2.5\sigma $$ 2.5 σ , $$2.4\sigma $$ 2.4 σ and $$2.2\sigma $$ 2.2 σ respectively. Motivated by these anomalies and by the abundant $$B^*$$ B ∗ data samples, we investigate possible New Physics effects of the vector leptoquark in the semileptonic decay $$\bar{B}^*_{u,d,s,c} \rightarrow V \tau ^-\bar{\nu }_{\tau }$$ B ¯ u , d , s , c ∗ → V τ - ν ¯ τ ($$V=D^*_{u,d,s},J/\psi $$ V = D u , d , s ∗ , J / ψ ). which is induced by $$b\rightarrow c \tau ^-\bar{\nu }_{\tau }$$ b → c τ - ν ¯ τ at the quark level. Using the best fit solutions for the new operator Wilson coefficients and the relevant form factors which are obtained in the light-front quark model, we find that (i) the contributions of the vector leptoquark to $$d{\varGamma }^{(L)}/dq^2(\bar{B}^*_{u,d,s,c} \rightarrow V \tau ^-\bar{\nu }_{\tau })$$ d Γ ( L ) / d q 2 ( B ¯ u , d , s , c ∗ → V τ - ν ¯ τ ) and $$R^{*(L)}_{V}(q^2)$$ R V ∗ ( L ) ( q 2 ) to be significant; (ii) the two best fit solutions in the vector leptoquark are indistinguishable from each other and give similar amounts of enhancements to these two observables; (iii) both two cases of the vector leptoquark give nearly same results as those of the Standard Model for $$A_{FB}^{\tau }(q^2)$$ A FB τ ( q 2 ) , $$P_{\tau }(q^2)$$ P τ ( q 2 ) and $$F_{L}^{*V}(q^2)$$ F L ∗ V ( q 2 ) . We hope that the numerical results in this work will be tested in the future high energy experiments.

Recently, several hints of lepton nonuniversality have been observed in the semileptonic B meson decays in terms of both in the neutral current (b → sll) and charged current (b → clν l) transitions. Motivated by these inspiring results, we perform the analysis of the baryon decays Σ b → Σ c lν l and Ω b → Ω c lν l ðl ¼ e; μ; τÞ which are mediated by b → clν 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 BðB → D ðÃÞ lν l Þ, R D ðÃÞ and R J=ψ 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 Σ b → Σ c lν l and Ω b → Ω c lν 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.

Leptoquarks have been suggested to solve a variety of discrepancies between the expected and observed phenomenon. In this paper, we investigate the effects of scalar leptoquarks on the lepton flavor violating B meson rare decays which involve the quarkThe leptoquark parameter spaces are constrained by using the recently measured upper limits on B(B 0 s → ℓ − i ℓ + j ) and B(B → K ( * ) ℓ − i ℓ + j ). Using such constrained leptoquark parameter spaces, some relevant physical quantities are predicted and we find that the constrained new physics parameters in the leptoquark model have very obvious effects on the relevant physical quantities. With future measurements of observables in B → K ( * ) ℓ − i ℓ + j decays at the LHCb, more and more differentiated from the other new physics explanations could be tested.