Studying B1(1/2+) → B2(1/2+)l+l- semileptonic weak baryon decays with the SU(3) flavor symmetry

Motivated by recent anomalies in flavor changing neutral current b -> sl(+)l(-) transitions, we study B-1 -> B(2)l(+)l(-)(l = e, mu, tau) semileptonic weak decays with the SU(3) flavor symmetry, where B-1,B-2 are the spin-1/2 baryons of single bottomed antitriplet T-b3, single charmed antitriplet T-c3, or light baryons octet T-8. Using the SU(3) irreducible representation approach, we first obtain the amplitude relations among different decay modes and then predict the relevant not-yet measured observables of T-b3 -> T(8)l(+)l(-), T-c3 -> T(8)l(+)l(-), and T-8 -> T'(8)l(+)l(-) decays. (a) We calculate the branching ratios of the T-b3 -> T-8 mu(+)mu(-) and T-b3 -> T-8 tau(+)tau(-) decay modes in the whole q(2) region and in the different q(2) bins by the measurement of Lambda(0)(b) -> Lambda(0)mu(+)mu(-). Many of them are obtained for the first time. In addition, the longitudinal polarization fractions and the leptonic forward-backward asymmetries of all T-b3 -> T(8)l(+)l(-) decays are very similar to each other in certain q(2) bins due to the SU(3) flavor symmetry. (b) We analyze the upper limits of B(T-c3 -> T(8)l(+)l(-)) by using the experimental upper limits of B(Lambda(+)(c) -> p mu(+)mu(-)) and B(Lambda(+)(c) -> pe(+)e(-)), and find the experimental upper limit of B(Lambda(+)(c) -> p mu(+)mu(-)) giving the effective bounds on the relevant SU(3) flavor symmetry parameters. The predictions of B(Xi(0)(c) -> Xi(0)e(+)e(-)) and B(Xi(0)(c) -> Xi(0)mu(+)mu-) will be different between the single-quark transition dominant contributions and the W-exchange dominant ones. (c) As for T-8 -> T'(8)l(+)l(-) decays, we analyze the single-quark transition contributions and the W-exchange contributions by using the two experimental measurements of B(Xi(0) -> Lambda(0)e(+)e(-)) and B(Sigma(+) -> p mu(+)mu(-)), and give the branching ratio predictions by assuming either single-quark transition dominant contributions or the W-exchange dominant contributions. According to our predictions, some observables are accessible to the experiments at BESIII, LHCb and Belle-II.