Searching for possible evidences of new physics in $Bto V_1 V_2$

We explore the decays of $Bto V_1V_2$ ($V_{1,2}= (rho, omega,K^*, phi)$ and $B= (B^0, B^+,B_s)$) with transverse polarizations. We explicitly evaluate the eigenstates of T-odd scalar operators involving spins for the first time, which offer physical insight among the T violating observables. Based on the helicity suppression of tree operators for transverse polarizations in the standard model (SM), we deduce that $Delta phi_p = phi_parallel - phi_perp=0$ with $phi_{perp,parallel}$ the complex phases of the transverse amplitudes. In contrast, the experiments show that $Delta phi _p (B^0 to K^{*0} omega)= -0.84pm 0.54$, which would be a signal of new physics. There is also a discrepancy between our result in the SM and the experimental data for the transverse polarized branching ratio in $B^0 to K^{*0} omega$. In addition, by counting the helicity flips, we obtain that $sin(phi_p ) approx 0$ in $Bto V_1T_2$ with $T_2$ an arbitrary spin-$n$ meson ($nge1$).

Non-leptonic two-body decays of $Lambda_b^0$ in light-front quark model

We study the non-leptonic two-body weak decays of $Lambda_b^0 to p M$ with $ M=(pi^-,K^-)$ and $(rho^-,K^{*-})$ in the light-front quark model under the generalized factorization ansatz. By considering the Fermi statistic between quarks and determining spin-flavor structures in baryons, we calculate the branching ratios (${cal B}$s) and CP-violating rate asymmetries ($mathcal{A}_{CP}$s) in the decays. Explicitly, we find that ${cal B}( Lambda_b^0 to p pi^- ,pK^-)=(4.18pm0.15pm0.30, 5.76pm0.88pm0.23)times10^{-6}$ and ${mathcal{A}_{CP}}( Lambda_b^0 to p pi^- ,,pK^-)=(-3.60pm0.14pm0.14, 6.36pm0.21pm0.18)%$ in comparison with the data of ${cal B}( Lambda_b^0 to p pi^- ,pK^-)=(4.5pm0.8, 5.4pm1.0)times10^{-6}$ and ${mathcal{A}_{CP}}( Lambda_b^0 to p pi^- ,pK^-)=(-2.5pm 2.9, -2.5pm2.2)%$ given by the Particle Data Group, respectively. We also predict that ${cal B}( Lambda_b^0 to p rho^-,pK^{*-} )=(12.13pm3.27pm0.91, 2.58pm0.87pm0.13)times 10^{-6}$ and ${mathcal{A}_{CP}}( Lambda_b^0 to p rho^-,pK^{*-} )=(-3.32pm0.00pm0.14,19.25pm0.00pm0.80)%$, which could be observed by the experiments at LHCb.

Semileptonic weak decays of anti-triplet charmed baryons in the light-front formalism

We systematically study the semileptonic decays of ${bf B_c} to {bf B_n}ell^+ u_{ell}$ in the light-front constituent quark model, where ${bf B_c}$ represent the anti-triplet charmed baryons of $(Xi_c^0,Xi_c^+,Lambda_c^+)$ and ${bf B_n}$ correspond to the octet ones. We determine the spin-flavor structures of the constituents in the baryons with the Fermi statistics and calculate the decay branching ratios (${cal B}$s) and averaged asymmetry parameters ($alpha$s) with the helicity formalism. In particular, we find that ${cal B}( Lambda_c^+ to Lambda e^+ u_{e}, ne^+ u_{e})=(3.55pm1.04, 0.36pm0.15)%$, ${cal B}( Xi_c^+ to Xi^0 e^+ u_{e},Sigma^0 e^+ u_{e},Lambda e^+ u_{e})=(11.3pm3.35), 0.33pm0.09,0.12pm0.04%$ and ${cal B}( Xi_c^0 to Xi^- e^+ u_{e},Sigma^- e^+ u_{e})=(3.49pm0.95,0.22pm0.06)%$. Our results agree with the current experimental data. Our prediction for ${cal B}( Lambda_c^+ to n e^+ u_{e})$ is consistent with those in the literature, which can be measured by the charm-facilities, such as BESIII and BELLE. Some of our results for the $Xi_c^{+(0)}$ semileptonic channels can be tested by the experiments at BELLE as well as the ongoing ones at LHCb and BELLEII.

Semileptonic decays of $Lambda_c^+$ in dynamical approaches

We study the semileptonic decays of $Lambda_c^+ to Lambda(n)ell^+ u_{ell}$ in two relativistic dynamical approaches of the light-front constituent quark model (LFCQM) and MIT bag model (MBM). By considering the Fermi statistic between quarks and determining spin-flavor structures in baryons along with the helicity formalism in the two different dynamical models, we calculate the branching ratios (${cal B}$s) and averaged asymmetry parameters ($alpha$s) in the decays. Explicitly, we find that ${cal B}( Lambda_c^+ to Lambda e^+ u_{e})=(3.36pm0.87,3.48)%$ and ${alpha}( Lambda_c^+ to Lambda e^+ u_{e})=(-0.97pm0.03,-0.83)$ in (LFCQM, MBM), in comparison with the data of ${cal B}( Lambda_c^+ to Lambda e^+ u_{e})=(3.6pm0.4)%$ and ${alpha}( Lambda_c^+ to Lambda e^+ u_{e})=-0.86pm 0.04$ given by the Particle Data Group, respectively. We also predict that ${cal B}( Lambda_c^+ to n e^+ u_{e})=(0.57pm0.15, 3.6pm1.5)times 10^{-3}$ and ${alpha}( Lambda_c^+ to n e^+ u_{e})=(-0.98pm0.02,-0.96pm0.04)$ in LFCQM with two different scenarios for the momentum distributions of quarks in the neutron, and ${cal B}( Lambda_c^+ to n e^+ u_{e})= 0.279times 10^{-2}$ and ${alpha}( Lambda_c^+ to n e^+ u_{e})=-0.87$ in MBM, which could be tested by the ongoing experiments at BESIII, LHCb and BELLEII.

Mixing effects of $Sigma^0-Lambda^0$ in $Lambda_c^+$ decays

We analyze the mixing between $Sigma^0$ and $Lambda^0$ based on the baryon masses. We distinguish the contributions from QCD and QED in the baryon mass splittings. We find that the mixing angle between $Sigma^0$ and $Lambda^0$ is $(2.07pm 0.03)times 10^{-2} $, which leads to the decay branching fraction and up-down asymmetry of $Lambda_c^+ to Sigma^0 e^+ u_e$ to be ${cal B}(Lambda_c^+ to Sigma^0 e^+ u_e)=(1.5pm 0.2)times 10^{-5}$ and $alpha(Lambda_c^+ to Sigma^0 e^+ u_e)=-0.86pm 0.04$, respectively. Moreover, we obtain that $Delta {cal B}equiv {cal B}(Lambda_c^+to Sigma^0 pi^+) - {cal B}(Lambda_c^+to Sigma^+pi^0)=(3.8pm 0.5)times 10^{-4}$ and $Delta alpha equivalpha(Lambda_c^+to Sigma^0 pi^+) -alpha(Lambda_c^+to Sigma^+pi^0)=(-1.6pm 0.7)times10^{-2}$, which should vanish without the mixing.

Charmed Baryon Weak Decays with Vector Mesons

We give a systematic study of ${bf B}_cto {bf B}_n V$ decays, where ${bf B}_c$ and $ {bf B}_n$ correspond to the anti-triplet charmed and octet baryons, respectively, while $V$ stand for the vector mesons. We calculate the color-symmetric contributions to the decays from the effective Hamiltonian with the factorization approach and extract the anti-symmetric ones based on the experimental measurements and $SU(3)_F$ flavor symmetry. We find that most of the existing experimental data for ${bf B}_cto {bf B}_n V$ are consistent with our fitting results. We present all the branching ratios of the Cabbibo allowed, singly Cabbibo suppressed and doubly Cabbibo suppressed decays of ${bf B}_cto {bf B}_n V$. The decay parameters for the daughter baryons and mesons in ${bf B}_cto {bf B}_n V$ are also evaluated. In particular, we point out that the Cabbibo allowed decays of $Lambda_c^+ to Lambda^0 rho^+$ and $ Xi_c^0 to Xi^- rho^+$ as well as the singly Cabbibo suppressed ones of $Lambda_c^+ to Lambda^0 K^{*+}$, $Xi_c^+ to Sigma^+ phi$ and $Xi_c^0to Xi^- K^{*+}$ have large branching ratios and decay parameters with small uncertainties, which can be tested by the experimental searches at the charm facilities.

Asymmetries of anti-triplet charmed baryon decays

We analyze the decay processes of ${bf B}_c to {bf B}_n M$ with the $SU(3)_F$ flavor symmetry and spin-dependent amplitudes, where ${bf B}_c({bf B}_n)$ and $M$ are the anti-triplet charmed (octet) baryon and nonet meson states, respectively. In the $SU(3)_F$ approach, it is the first time that the decay rates and up-down asymmetries are fully and systematically studied without neglecting the ${cal O}(overline{15})$ contributions of the color anti-symmetric parts in the effective Hamiltonian. Our results of the up-down asymmetries based on $SU(3)_F$ are quite different from the previous theoretical values in the literature. In particular, we find that the up-down symmetry of $ alpha(Lambda_c^+to Xi^0 K^+)_{SU(3)} = 0.94^{+0.06}_{-0.11}$, which is consistent with the recent experimental data of $0.77pm0.78$ by the BESIII Collaboration, but predicted to be zero in the literature. We also examine the $K_S^0-K_L^0$ asymmetries between the decays of ${bf B}_c to {bf B}_n K_S^0$ and ${bf B}_c to {bf B}_n K_L^0$ with both Cabibbo-allowed and doubly Cabibbo-suppressed transitions.

Three-body charmed baryon Decays with SU(3) flavor symmetry

We study the three-body anti-triplet ${bf B_c}to {bf B_n}MM$ decays with the $SU(3)$ flavor ($SU(3)_f$) symmetry, where ${bf B_c}$ denotes the charmed baryon anti-triplet of $(Xi_c^0,-Xi_c^+,Lambda_c^+)$, and ${bf B_n}$ and $M(M)$ represent baryon and meson octets, respectively. By considering only the S-wave $MM$-pair contributions without resonance effects, the decays of ${bf B_c}to {bf B_n}MM$ can be decomposed into irreducible forms with 11 parameters under $SU(3)_f$, which are fitted by the 14 existing data, resulting in a reasonable value of $chi^2/d.o.f=2.8$ for the fit. Consequently, we find that the triangle sum rule of ${cal A}(Lambda_c^+to nbar K^0 pi^+)-{cal A}(Lambda_c^+to pK^- pi^+)-sqrt 2 {cal A}(Lambda_c^+to pbar K^0 pi^0)=0$ given by the isospin symmetry holds under $SU(3)_f$, where ${cal A}$ stands for the decay amplitude. In addition, we predict that ${cal B}(Lambda_c^+to n pi^{+} bar{K}^{0})=(0.9pm 0.8)times 10^{-2}$, which is $3-4$ times smaller than the BESIII observation, indicating the existence of the resonant states. For the to-be-observed ${bf B_c}to {bf B_n}MM$ decays, we compute the branching fractions with the $SU(3)_f$ amplitudes to be compared to the BESIII and LHCb measurements in the future.