L. Szymanowski

Mueller Navelet jets at LHC — complete next-to-leading BFKL calculation

We calculate cross section and azimuthal decorrellation of Mueller Navelet jets at the LHC in the complete next-lo-leading order BFKL framework, i.e. including next-to-leading corrections to the Green’s function as well as next-to-leading corrections to the Mueller Navelet vertices. The obtained results for standard observables proposed for studies of Mueller Navelet jets show that both sources of corrections are of equal, big importance for final magnitude and final behavior of observables. The astonishing conclusion of our analysis is that the observables obtained within the complete next-lo-leading order BFKL framework of the present paper are quite similar to the same observables obtained within next-to-leading DGLAP type treatment. This fact sheds doubts on general belief that the studies of Mueller Navelet jets at the LHC will lead to clear discrimination between the BFKL and the DGLAP dynamics.

Towards a Solution of the Charmonium Production Controversy: k ⊥ Factorization versus Color-Octet Mechanism

The cross section of \chi_{cJ} hadroproduction is calculated in the k_t-factorization approach. We find a significant contribution of the \chi_{c1} state due to non-applicability of the Landau-Yang theorem because of off-shell gluons. The results are in agreement with data and, in contrast to the collinear factorization, show a dominance of the color singlet part and a strong suppression of the color octet contribution. Our results could therefore lead to a solution of the longstanding controversy between the color singlet model and the color octet mechanism.

Towards a Solution of the Charmonium Production Controversy: k[perpendicular] Factorization versus Color-Octet Mechanism

The cross section of chi(cJ) hadroproduction is calculated in the k( perpendicular)-factorization approach. We find a significant contribution of the chi(c1) state due to non-applicability of the Landau-Yang theorem because of off-shell gluons. The results are in agreement with data and, in contrast to the collinear factorization, show a dominance of the color-singlet part and a strong suppression of the color octet contribution. Our results could therefore lead to a solution of the long-standing controversy between the color-singlet model and the color-octet mechanism.

QCD factorization of exclusive processes beyond leading twist: gamma*T ---> rho(T) impact factor with twist three accuracy

Abstract We describe a consistent approach to factorization of scattering amplitudes for exclusive processes beyond the leading twist approximation. The method involves the Taylor expansion of the scattering amplitude in the momentum space around the dominant light-cone direction and thus naturally introduces an appropriate set of non-perturbative correlators which encode effects not only of the lowest but also of the higher Fock states of the produced particle. The reduction of original set of correlators to a set of independent ones is achieved with the help of equations of motion and invariance of the scattering amplitude under rotation on the light cone. We compare the proposed method with the covariant method formulated in the coordinate space, based on the operator product expansion. We prove the equivalence of two proposed parametrizations of the ρ T distribution amplitudes. As a concrete application, we compute the expressions of the impact factor for the transition of virtual photon to transversally polarised ρ-meson up to the twist 3 accuracy within these two quite different methods and show that they are identical.

Direct

The hadroproduction of direct

J/\psi

J/\ensuremath{\psi}

hadroproduction in

in the framework of the

k^-

{k}_{\ensuremath{\perp}}

perpendicular factorization and the color octet mechanism

-factorization approach is studied. The color-singlet contribution is essentially larger than in the collinear approach but is still an order of magnitude below the data. The deficit may be well described by the color octet contribution with the value of the matrix element

On AdS/QCD correspondence and the partonic picture of deep inelastic scattering

〈0|{O}_{8}^{J/\ensuremath{\psi}}{(}^{3}{S}_{1})|0〉