Search

Abstract Semileptonic three-body $$D \rightarrow M\ell ^+\nu _\ell $$ D → M ℓ + ν ℓ decays, non-leptonic $$M \rightarrow VP$$ M → V P decays, and semileptonic four-body $$D \rightarrow M(M \rightarrow VP)\ell ^+\nu _\ell $$ D → M ( M → V P ) ℓ + ν ℓ decays are analyzed using the SU(3) flavor symmetry/breaking approach, where $$\ell =e/\mu $$ ℓ = e / μ , $$M=A/T$$ M = A / T , and A/T/V/P denote the axial-vector/tensor/vector/pseudoscalar mesons, respectively. In terms of SU(3) flavor symmetry/breaking, the decay amplitudes of the $$D \rightarrow M \ell ^+ \nu _\ell $$ D → M ℓ + ν ℓ decays and the vertex coefficients of the $$M \rightarrow VP$$ M → V P decays are related. The relevant non-perturbative parameters of the $$D \rightarrow A\ell ^+\nu _\ell $$ D → A ℓ + ν ℓ , $$A \rightarrow VP$$ A → V P , and $$T \rightarrow VP$$ T → V P decays are constrained by the present experimental data, and the non-perturbative parameters of $$D \rightarrow T\ell ^+\nu _\ell $$ D → T ℓ + ν ℓ decays are taken from the results in the light-front quark model since no experimental data are available at present. The branching ratios of the $$D \rightarrow M \ell ^+ \nu _\ell $$ D → M ℓ + ν ℓ , $$M \rightarrow VP$$ M → V P , and $$D\rightarrow M(M\rightarrow VP)\ell ^+\nu _\ell $$ D → M ( M → V P ) ℓ + ν ℓ decays are then predicted. We find that some processes receive both tensor and axial-vector resonant contributions, while other processes receive only axial-vector resonant contributions. In cases where both kinds of resonant contributions exist, the axial-vector contributions are dominant. Some branching ratios with axial-vector resonance states are large, and they may be measured experimentally in the near future. In addition, the sensitivities of the branching ratios of $$D \rightarrow A \ell ^+ \nu _\ell $$ D → A ℓ + ν ℓ and $$A \rightarrow VP$$ A → V P decays to the parameters are also investigated, and some decay branching ratios are found to be sensitive to the non-perturbative parameters.

Many exclusive c→d/sℓ+νℓ(ℓ=e,μ,τ) transitions have been well measured, and they can be used to test the theoretical calculations. Motivated by this, we study the D→P/V/Sℓ+νℓ decays induced by the c→d/sℓ+νℓ 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→Pℓ+νℓ, D→Vℓ+νℓ or D→Sℓ+νℓ decays can be related by using the SU(3) flavor symmetry and by considering the SU(3) flavor breaking. Using relevant data, we predict the not yet measured or not yet well measured processes in the D→P/V/Sℓ+νℓ decays. We find that the SU(3) flavor symmetry approach works well in the D→P/Vℓ+νℓ decays. Many branching ratios of the D→Sℓ+νℓ decays are predicted by using the data of the Ds+→f0(980)e+νe and D→S(S→P1P2)ℓ+νℓ 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→Sℓ+νℓ decays need to be further tested, and our predictions of the D→Sℓ+νℓ 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.

Abstract Motivated by the persistent anomalies reported in the $$b\rightarrow c \tau \bar{\nu }$$ b → c τ ν ¯ data, we investigate the semileptonic decays $$\bar{B}^* \rightarrow V \tau ^-\bar{\nu }_{\tau } (V=D^*_{u,d,s},J/\psi )$$ B ¯ ∗ → V τ - ν ¯ τ ( V = D u , d , s ∗ , J / ψ ) , within the Standard Model and beyond. The relevant transition form factors, being calculated in the covariant light-front quark model, is the main source of theoretical uncertainties. Using various best-fit solutions for the new operator Wilson coefficients, we report numerical results on various observables related to the processes $$\bar{B}^* \rightarrow V \tau ^-\bar{\nu }_{\tau }$$ B ¯ ∗ → V τ - ν ¯ τ , such as the branching ratios, the ratio of branching fractions, the hadron and lepton polarization asymmetries, the forward–backward asymmetries and the convexity parameter. We also predict the $$q^2$$ q 2 distribution of these observables both within the Standard Model and in various new physics scenarios. The accessible observables are studied in order to assess their sensitivity to the different new physics scenarios. We can find that some of the new physics scenarios can be differentiated from each other by using these observables and their correlations. We also find that some observables of these decay modes are sizeable and deviate significantly (for new physics coupling parameter $$S_R$$ S R especially) from their corresponding standard model values, which are expected to be within the reach of Run III of Large Hadron Collider experiment. And experimental information on these distributions which will be testified in the future can help to disentangle the dynamical origin of the current anomalies.

Motivated by the first measured Δ+→pe+e− decay by the HADES Collaboration, electromagnetic Dalitz baryon decays from the spin 32 decuplet (T10) to the spin 12 octet (T8) baryons are investigated by using the SU(3) flavor symmetry/breaking in this paper. All decay amplitudes of T10→T8ℓ+ℓ−(ℓ=e,μ) electromagnetic Dalitz decays could be related by the SU(3) flavor symmetry/breaking, so the amplitudes can be obtained by the measured branching ratio of Δ+→pe+e− decay from the HADES Collaboration. The branching ratios, the lepton flavor universality, and the ratios B(T10→T8ℓ+ℓ−)B(T10→T8γ) are predicted by the relevant experimental data. T10→T8μ+μ− electromagnetic Dalitz decays are studied for the first time. All predicted B(T10→T8ℓ+ℓ−) except B(Ξ⁎0→Ξ0μ+μ−) and B(Ξ⁎−→Ξ−μ+μ−) are on the order of O(10−5−10−7), and these decays could be observed and could be used to test the SU(3) flavor symmetry/breaking approach in the electromagnetic Dalitz decays by HADES, PANDA, BESIII, and other experiments in the near future.

Motivated by recent RD, RD⁎ and RJ/ψ anomalies in B→Dℓ−ν¯ℓ, B→D⁎ℓ−ν¯ℓ and Bc→J/ψℓ−ν¯ℓ decays, respectively, we study possible R-parity violating supersymmetric effects in Bc→J/ψℓ−ν¯ℓ,ηcℓ−ν¯ℓ and Λb→Λcℓ−ν¯ℓ decays, which are also induced by b→cℓ−ν¯ℓ at quark level. We find that (I) the constrained slepton exchange couplings λi33λ˜i23′⁎ involving in b→cτ−ν¯τ transition from relevant latest experimental data still have quite large effects on all (differential) branching ratios and the normalized forward–backward asymmetries of the exclusive semileptonic b→cτ−ν¯τ decays as well as the ratios of the (differential) branching ratios; (II) after satisfying the data of RD and RD⁎, the upper limit of RJ/ψ, Rηc and RΛc could be increased by 10%, 112% and 24%, respectively, from their upper limits of the Standard Model predictions by the λi33λ˜′⁎i23 couplings. The results in this work could be used to probe R-parity violating effects and will correlate with searches for direct supersymmetric signals at the running LHCb and the forthcoming Belle-II.

Inspired by the recent anomaly measurements of the lepton-flavor violating decays h→μτ and the lepton flavor non-universality in decays b¯→s¯ℓ−ℓ+, we investigate the lepton flavor violating exclusive b¯→s¯ℓi−ℓj+(i≠j and ℓ=e,μ,τ) decays within supersymmetry. Relevant R-parity violating couplings are constrained by using the latest experimental upper limits on the branching ratios of Bs→ℓi−ℓj+ and B→K(⁎)ℓi−ℓj+ flavor changing neutral current processes, and we find that all relevant branching ratios are very sensitive to the moduli of the squark and sneutrino exchange coupling products. In addition, the constrained lepton number violating effects on the dilepton invariant mass spectra, the single lepton polarization asymmetries and the differential forward–backward asymmetries are also studied. These lepton-flavor violating B decays could be used for the search of lepton flavor violation at the running LHC and the forthcoming Belle-II.

A lot of branching ratios of the exclusive c→d/sℓ+νℓ (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/sℓ+νℓ 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 yet. We find that the R-parity violating effects due to slepton exchange could be large on the branching ratios of Dd/s→e+νe decays and the normalized forward-backward asymmetries of Du/d→π/Kℓ+νℓ as well as Ds→Kℓ+νℓ decays, and the constrained squark exchange couplings have negligible effects in the exclusive c→d/sℓ+νℓ decays. 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 significant divergence between the SM predictions and experimental measurements for the ratios, RD(⁎)≡B(B¯→D(⁎)τ-ν¯τ)/B(B¯→D(⁎)l′-ν¯l′) with (l′=e,μ), implies possible hint of new physics in the flavor sector. In this paper, motivated by the “RD(⁎) puzzle” and abundant B⁎ data samples at high-luminosity heavy-flavor experiments in the future, we try to probe possible effects of new physics in the semileptonic B¯u,d,s⁎→Pl-ν¯l (P=D,Ds,π,K) decays induced by b→(u,c)l-ν¯l transitions in the model-independent vector and scalar scenarios. Using the spaces of NP parameters obtained by fitting to the data of RD and RD⁎, the NP effects on the observables including branching fraction, ratio RP⁎, lepton spin asymmetry, and lepton forward-backward asymmetry are studied in detail. We find that the vector type couplings have large effects on the branching fraction and ratio RP⁎. Meanwhile, the scalar type couplings provide significant contributions to all of the observables. The future measurements of these observables in the B¯⁎→Pl-ν¯l decays at the LHCb and Belle-II could provide a way to crosscheck the various NP solutions to the “RD(⁎) puzzle”.

Many observables related to the neutral meson mixings have been measured, and these experimental measurements could be used to test various new physics models. The two-Higgs-doublet model is one of the simplest extensions of the standard model. In this paper, , , and mixings are explored in the minimal flavor violating two-Higgs-doublet models with type-C and type-III. Firstly, we perform a complete one-loop computation to the amplitudes of neutral meson mixings. Then the allowed parameter spaces of Yukawa couplings of charged scalars to quarks in both real and complex cases are obtained from all relevant latest experimental data. Finally, the theoretical predictions of relevant observables and the differences between type-III and type-C models are analyzed. [ABSTRACT FROM AUTHOR]

Recently, the Belle collaboration reported the first measurement of the τ lepton polarization Pτ(D*) in decay and a new measurement of the rate of the branching ratios R(D*), which are consistent with the Standard Model (SM) predictions. These could be used to constrain the New Physics (NP) beyond the SM. In this paper, we probe (ℓ = e, μ, τ) decays in the model-independent way and in the specific G(221) models with lepton flavour universality. Considering the theoretical uncertainties and the experimental errors at the 95% C.L., we obtain the quite strong bounds on the model-independent parameters and the specific G(221) model parameter rates. We find that the constrained NP couplings have no obvious effects on all (differential) branching ratios and their rates, nevertheless, many NP couplings have very large effects on the lepton spin asymmetries of decays and the forward–backward asymmetries of . So we expect precision measurements of these observables would be researched by LHCb and Belle-II. [ABSTRACT FROM AUTHOR]