Bound on a flux of ultra-high energy neutrinos in a scenario with extra dimensions

Assuming that a single-flavor diffuse neutrino flux dN_nu/dE_nu is equal to k*E_nu^(-2) in the energy range 10^(17) eV - 2.5*10^(19) eV, an upper bound on k is calculated in the ADD model as a function of the number of extra dimensions n and gravity scale M_D. An expected number of neutrino induced events at the Surface Detector array of the Pierre Auger Observatory is estimated.Comment: 7 pages, 6 figures, submitted to the Proceedings of the XXth International Seminar "Quarks-2018

OPE coefficient functions in terms of composite operators only. Singlet case

A method for calculating coefficient functions of the operator product expansion, which was previously derived for the non-singlet case, is generalized for the singlet coefficient functions. The resulting formula defines coefficient functions entirely in terms of corresponding singlet composite operators without applying to elementary (quark and gluon) fields. Both "diagonal" and "non-diagonal" gluon coefficient functions in the product expansion of two electromagnetic currents are calculated in QCD. Their renormalization properties are studied.Comment: 33 pages, 15 figures, minor corrections are mad

Operator product expansion coefficient functions in terms of composite operators only. Nonsinglet case

A new method for calculating the coefficient functions of the operator product expansion is proposed which does not depend explicitly on elementary fields. Coefficient functions are defined entirely in terms of composite operators. The method is illustrated in the case of QCD nonsinglet operators.Comment: Derivation of the main formula is improved. References are added. To appear in Physical Review

Hyperon Polarization in the Constituent Quark Model

We consider mechanism for hyperon polarization in inclusive production. The main role belongs to the orbital angular momentum and polarization of the strange quark-antiquark pairs in the internal structure of the constituent quarks. We consider a nucleon as a core consisting of the constituent quarks embedded into quark condensate. The nonperturbative hadron structure is based on the results of chiral quark models.Comment: 14 pages, LaTeX, 2 Figures, References adde