Analysis of the ?_{b}??l^{+}l^{-} decay in QCD

Experimentally, the detection and isolation of the heavy baryons is simple compared to the light systems since having the heavy quark makes their beam narrow. In recent years, considerable experimental progress has been made in the identification and spectroscopy of the heavy baryons containing a heavy bottom or charm quark (1-8). This evidence can be considered as a good signal to search also the decay channels of the heavy baryons such asb ! � ' þ ' � at the LHCb. This rare channel, induced by the flavor changing neutral currents of b ! s transition, serves as a testing ground for the standard model at loop level and is very sensitive to the new physics effects (9), such as supersymmetric particles (10), light dark matter (11). and also the fourth generation of the quarks and extra dimen- sions, etc. Moreover, this channel can be inspected as a useful tool in the exact determination of the Cabibbo- Kobayashi-Maskawa matrix elements, Vtb and Vts, CP and T violations, polarization asymmetries. Theoretically, there are some works devoted to the analysis of the heavy baryon decays, where in practically all of them the predictions of the heavy quark effective theory (HQET) for form factors have been used. Transition form factors of theb ! � c andc ! � decays have been studied in three point QCD sum rules in (12), the � b ! pltransition form factors have also been calcu- lated via three point QCD sum rules in the context of the HQETin (13) and in the framework of the SU(3) symmetry and HQET in (14). In the present work, using the most general form of the interpolating current for theb and also the distribution amplitudes ofbaryon, all form factors related to the electroweak penguin and weak box diagrams describing theb ! � ' þ ' � are calculated in the framework of the light cone QCD sum rules in full theory. The obtained results for the form factors are used to estimate the decay rate and branching ratio. This transition has been investigated in (15,16) also in the context of the HQET but in the same framework using the distribution amplitudes of theandb, respectively. Moreover, form factors, branching ratio, and dilepton forward-backward asymmetries are studied in (17-19) also within the context of the HQET. In (20-22), � b;c andb;c to nucleon tran- sitions are also evaluated using the nucleon wave functions in the light cone QCD sum rules approach. The plan of the paper is as follows: in Sec. II, the light cone QCD sum rules for the form factors are obtained using thedistribution amplitudes (DA's). The HQET relations among all form factors are also discussed in this section. Section III is dedicated to the numerical analysis of the sum rules for the form factors as well as numerical results of the decay rate and branching ratio.