Flavor Changing Neutral Currents Transition of the ΣQ\Sigma_{Q} to Nucleon in Full QCD and Heavy Quark Effective Theory

The loop level flavor changing neutral currents transitions of the $\Sigma_{b}\to n l^+l^-$ and $\Sigma_{c}\to p l^+l^-$ are investigated in full QCD and heavy quark effective theory in the light cone QCD sum rules approach. Using the most general form of the interpolating current for $\Sigma_{Q}$, $Q=b$ or $c$, as members of the recently discovered sextet heavy baryons with spin 1/2 and containing one heavy quark, the transition form factors are calculated using two sets of input parameters entering the nucleon distribution amplitudes, namely, QCD sum rules and lattice QCD inputs. The obtained results are used to estimate the decay rates of the corresponding transitions. Since such type transitions occurred at loop level in the standard model, they can be considered as good candidates to search for the new physics effects beyond the SM.Comment: 18 Pages and 13 Table

Magnetic Moments of Heavy ΞQ\Xi_{Q} Baryons in Light Cone QCD Sum Rules

The magnetic moments of heavy $\Xi_{Q}$ baryons containing a single charm or bottom quark are calculated in the framework of light cone QCD sum rules method. A comparison of our results with the predictions of the quark models is presented.Comment: 26 Pages, 8 Figures and 1 Tabl

Analysis of the rare semileptonic B_c \rar P(D,D_s) l^{+}l^{-}/\nu\bar{\nu} decays within QCD sum rules

Considering the gluon condensate corrections, the form factors relevant to the semileptonic rare B_c \rar D,D_s(J^{P}=0^{-}) l^{+}l^{-} with $l=\tau,\mu,e$ and B_c \rar D,D_s(J^{P}=0^{-})\nu\bar{\nu} transitions are calculated in the framework of the three point QCD sum rules. The heavy quark effective theory limit of the form factors are computed. The branching fraction of these decays are also evaluated and compared with the predictions of the relativistic constituent quark model. Analyzing of such type transitions could give useful information about the strong interactions inside the pseudoscalar $D_{s}$ meson and its structure.Comment: 32 Pages, 8 Figures and 6 Table

Strong Coupling Constants of Decuplet Baryons with Vector Mesons

We provide a comprehensive study of strong coupling constants of decuplet baryons with light nonet vector mesons in the framework of light cone QCD sum rules. Using the symmetry arguments, we argue that all coupling constants entering the calculations can be expressed in terms of only one invariant function even if the $SU(3)_f$ symmetry breaking effects are taken into account. We estimate the order of $SU(3)_f$ symmetry violations, which are automatically considered by the employed approach.Comment: 19 Pages, 4 Figures and 5 Table

Analysis of heavy spin--3/2 baryon--heavy spin--1/2 baryon--light vector meson vertices in QCD

The heavy spin--3/2 baryon--heavy spin--1/2 baryon vertices with light vector mesons are studied within the light cone QCD sum rules method. These vertices are parametrized in terms of three coupling constants. These couplings are calculated for all possible transitions. It is shown that correlation functions for these transitions are described by only one invariant function for every Lorenz structure. The obtained relations between the correlation functions of the different transitions are structure independent while explicit expressions of invariant functions depend on the Lorenz structure.Comment: 17 Pages, 6 Figures and 4 Table

Semileptonic Λb,c\Lambda_{b,c} to Nucleon Transitions in Full QCD at Light Cone

The tree level semileptonic $\Lambda_{b}\to pl\nu$ and $\Lambda_{c}\to nl\nu$ transitions are investigated using the light cone QCD sum rules approach in full theory. The spin--1/2, $\Lambda_{Q}$ baryon with $Q=b$ or $c$, is considered by the most general form of its interpolating current. The time ordering product of the initial and transition currents is expanded in terms of the nucleon distribution amplitudes with different twists. Considering two sets of independent input parameters entering to the nucleon wave functions, namely, QCD sum rules and Lattice QCD parameters, the related form factors and their heavy quark effective theory limits are calculated and compared with the existing predictions of other approaches. It is shown that our results satisfy the heavy quark symmetry relations for lattice input parameters and b case exactly and the maximum violation is for charm case and QCD sum rules input parameters. The obtained form factors are used to compute the transition rates both in full theory and heavy quark effective theory. A comparison of the results on decay rate of $\Lambda_{b}\to pl\nu$ with those predicted by other phenomenological methods or the same method in heavy quark effective theory with different interpolating current and distribution amplitudes of the $\Lambda_{b}$ is also presented.Comment: 18 Pages and 16 Table

The cranking formula and the spurious behaviour of the mass parameters

We discuss some aspects of the approach of the mass parameters by means of the simple cranking model. In particular, it is well known that the numerical application of this formula is often subject to ambiguities or contradictions. It is found that these problems are induced by the presence of two derivatives in the formula. To overcome these problems, we state a useful ansatz and we develop a number of simple arguments which tend to justify the removal of these terms. As soon as this is done, the formula becomes simpler and easier to interpret. In this respect, it is shown how the shell effects affect the mass parameters. A number of numerical tests help us in our conclusions.Comment: version 3 corrigendum of the ansatz of section V, corrigendum of the legend of Fig3. Submission = text file + 5 figure