Fragmentation of heavy quarks in polarized quarkonium in the effective heavy quark theory

Fragmentation of abantiquark into polarized B_c ^* mesons has been studied within the framework of the effective theory of heavy quarks. The functions ofb fragmentation into longitudinally polarized and transversely polarizedb S-wave states have been calculated with precise account for corrections of the first order in 1/m_b. The results are shown to agree with the corresponding calculations in quantum chromodynamics. Samara State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, p. 97–104, July, 1996.     

Weak radiative decay Λ b →Λγ in the heavy quark effective theory

The weak radiative decay Λ _b →Λγ is studied in the heavy quark effective theory treatings-quark as heavy. This rare decay is induced by the short distance electromagnetic penguins. Including corrections of the order of (1/m _Q), we obtain the transition matrix element and the corresponding decay width. The Isgur-Wise function is evaluated in the largeN _c limit and the branching ratio obtained is 1.48×10⁻⁵.     

Some two body non-leptonicB decays and estimation off D in the heavy quark effective theory

We have studied some of the two body nonleptonic decays ofB meson in the context of heavy quark effective theory using factorization hypothesis. Treatinga ₁ as a free parameter, we have obtained its value asa ₁=0.822±0.045, by correlating the experimental and predicted branching ratio for process. With this value ofa ₁ the branching ratios obtained for other decay channels are in good agreement with the experiment. The decay constant ofD meson is extracted to be 280.82 MeV. Heavy quark spin symmetry has also been tested.     

Anomalous thresholds and the Isgur-Wise function

The original de Rafael-Taron bound on the slope of the Isgur-Wise function at zero recoil is known to be violated in QCD by singularities appearing in an unphysical region. To be consistent, quark models must have corresponding singularity structures. In an existing relativistic quark-loop model, the meson-quark-antiquark vertex is such that the required singularity is an anomalous threshold. We also discuss the implications of another anomalous threshold, whose location is determined by quark masses alone.     

Center-symmetric effective theory for two-color quark matter

We revisit the center-symmetric dimensionally reduced effective theory for two-color Yang-Mills theory at high temperature. This effective theory includes an order parameter for deconfinement and thus allows to broaden the range of validity of the conventional three-dimensional effective theory (EQCD) towards the confining phase transition. We extend the previous results by including the effects of massive quarks with nonzero baryon chemical potential. The parameter space of the theory is constrained by leading-order matching to the Polyakov loop effective potential of two-color QCD. Once all the parameters are fixed, the effective theory can provide model-independent predictions for the physics above the deconfinement transition, thus bridging the gap between large-scale numerical simulations and semi-analytical calculations within phenomenological models.