Lech Szymanowski

Confronting Mueller-Navelet jets in NLL BFKL with LHC experiments at 7 TeV

A bstractMore than 25 years ago, Mueller Navelet jets were proposed as a decisive test of BFKL dynamics at hadron colliders. We here study this process at NLL BFKL accuracy, taking into account NLL corrections to the Green’s function and to the jet vertices. We present detailed predictions for various observables that can be measured at LHC in ongoing experiments like ATLAS or CMS at

Perturbative odderon in the dipole model

\sqrt{s}=7

Effective action for multi-Regge processes in QCD

TeV: the cross-section, the azimuthal correlations and the angular distribution of these jets. For this purpose, we apply realistic kinematical cuts and binning, and study the dependence of our results with respect to several parameters. We then compare our results with those that can be obtained in a fixed order NLO treatment, and propose specific observables which could actually be used as a probe of BFKL dynamics.

Next-to-leading order corrections to timelike, spacelike, and double deeply virtual Compton scattering

Abstract We show that, in the framework of Muellers dipole model, the perturbative QCD odderon is described by the dipole model equivalent of the BFKL equation with a C-odd initial condition. The eigenfunctions and eigenvalues of the odderon solution are the same as for the dipole BFKL equation and are given by the functions En,ν and χ(n,ν) correspondingly, where the C-odd initial condition allows only for odd values of n. The leading high-energy odderon intercept is given by α odd −1= 2α s N c π χ(n=1,ν=0)=0 in agreement with the solution found by Bartels, Lipatov and Vacca. We proceed by writing down an evolution equation for the odderon including the effects of parton saturation. We argue that saturation makes the odderon solution a decreasing function of energy.

Timelike and spacelike deeply virtual Compton scattering at next-to-leading order

Abstract We construct the effective Lagrangian describing QCD in the multi-Regge kinematics. It is obtained from the original QCD Lagrangian by eliminating modes of gluon and quark fields not appearing in this underlying kinematics.

Mueller Navelet jets at LHC - complete NLL BFKL calculation

We calculate the O({alpha}{sub s}) corrections to the timelike, spacelike, and double deeply virtual Compton scattering amplitudes in the generalized Bjorken scaling region. Special attention is devoted to studies of the difference between the next-to-leading order timelike and spacelike coefficient functions, which plays for this process a role analogous to the large K factor which was much discussed in the analysis of inclusive Drell-Yan cross sections. Also in the present studies the timelike nature of the hard scale gives rise to a new absorptive part of the amplitude and to the presence of characteristic {pi}{sup 2} terms, which can potentially lead to sizable corrections.

Violation of energy–momentum conservation in Mueller–Navelet jets production

We study timelike and spacelike virtual Compton scattering in the generalized Bjorken scaling regime at next to leading order in the strong coupling constant, in the medium energy range which will be studied intensely at JLab12 and in the COMPASS-II experiment at CERN. We show that the Born amplitudes get sizeable O(alpha_s) corrections and, even at moderate energies, the gluonic contributions are by no means negligible. We stress that the timelike and spacelike cases are complementary and that their difference deserves much special attention.

Symmetry properties of the effective action for high-energy scattering in QCD

For the first time, a next-to-leading BFKL study of the cross s ection and azimuthal decorrellation of Mueller Navelet jets is performed, i.e. including next-t o-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 and big importance for final magni tude and final behavior of observables, in particular for the LHC kinematics investigated here in detail. The astonishing conclusion of our analysis is that the observables obtained within the c omplete next-lo-leading order BFKL framework of the present paper are quite similar to the same observables obtained within nextto-leading logarithm 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.

Evaluating the double parton scattering contribution to Mueller-Navelet jets production at the LHC

Abstract We study effects related to violation of energy–momentum conservation inherent to the BFKL approach, in the particular case of Mueller–Navelet jets production. We argue, based on the comparison of the lowest order non-trivial corrections O ( α s 3 ) to the cross section with predictions of an exact calculation, that the inclusion of next-to-leading order BFKL corrections to the jet production vertex significantly reduces the importance of these effects.

Can one measure timelike Compton scattering at LHC

The effective action for the multi-Regge asymptotics is considered as a first step in calculating the unitarity correction to the perturbative pomeron. It can be derived from the original QCD action by intgrating out certain modes of the fields in the functional integral. The derivation is described for the case without fermions.