Grigorios Chachamis

On the singular behaviour of scattering amplitudes in quantum field theory

A bstractWe analyse the singular behaviour of one-loop integrals and scattering amplitudes in the framework of the loop-tree duality approach. We show that there is a partial cancellation of singularities at the loop integrand level among the different components of the corresponding dual representation that can be interpreted in terms of causality. The remaining threshold and infrared singularities are restricted to a finite region of the loop momentum space, which is of the size of the external momenta and can be mapped to the phase-space of real corrections to cancel the soft and collinear divergences.

Monte Carlo techniques in small-x physics: Formal studies and phenomenology

We discuss the solution to the BFKL equation in the adjoint representation at LO and NLO accuracy for the N = 4 SUSY theory. We use Monte Carlo techniques to study numerically the Gluon Green’s function at LO and NLO directly written in the transverse momentum space which allows for the factorization of its infrared divergencies. Finally, we discuss the applicability of our approach to phenomenological searches for the BKP Odderon at the LHC.

The loop-tree duality at work

We review the recent developments of the loop-tree duality method, focussing our discussion on analysing the singular behaviour of the loop integrand of the dual representation of one-loop integrals and scattering amplitudes. We show that within the loop-tree duality method there is a partial cancellation of singularities at the integrand level among the different components of the corresponding dual representation. The remaining threshold and infrared singularities are restricted to a finite region of the loop momentum space, which is of the size of the external momenta and can be mapped to the phase-space of real corrections to cancel the soft and collinear divergences.

Heavy quark impact factor in kT-factorization

A bstractWe present the calculation of the finite part of the heavy quark impact factor at next-to-leading logarithmic accuracy in a form suitable for phenomenological studies such as the calculation of the cross-section for single bottom quark production at the LHC within the kT -factorization scheme.

Attacking One-loop Multi-leg Feynman Integrals with the Loop-Tree Duality

We discuss briefly the first numerical implementation of the Loop-Tree Duality (LTD) method. We apply the LTD method in order to calculate ultraviolet and infrared finite multi-leg one-loop Feynman integrals. We attack scalar and tensor integrals with up to six legs (hexagons). The LTD method shows an excellent performance independently of the number of external legs.

NNLO W Pair Production at the LHC: Status Report

We discuss the result with full mass dependence for the virtual NNLO QCD corrections to the W boson pair production in the quark-anti-quark annihilation channel. We also report on our progress regarding the treatment of the double-real radiat ive corrections which, along with the virtual-real corrections, are the other two necessary ingr edients for a theoretical prediction of the total cross section for W + W − production to NNLO accuracy.

Heavy quark impact factor and single bottom quark production at the LHC

Grigorios Chachamis Instituto de Física Corpuscular, Universitat de València – Consejo Superior de Investigaciones Científicas, Parc Científic, E-46980 Paterna (Valencia), Sp ain E-mail: grigorios.chachamis@ific.uv.es Michal Deák ∗ Instituto de Física Corpuscular, Universitat de València – Consejo Superior de Investigaciones Científicas, Parc Científic, E-46980 Paterna (Valencia), Sp ain E-mail: michal.deak@ific.uv.es

High Precision Gauge Boson Pair Production at the LHC

We discuss the recent derivation of the two loop virtual QCD corrections to the W boson pair production in the quark-anti-quark-annihilation channel in the limit where all kinematical invariants are large compared to the mass of the W boson. In particular, we describe the use of the PSLQ algorithm on an example integral.

Inclusive three- and four-jet production in multi-Regge kinematics at the LHC

A study of differential cross sections for the production of three and four jets in multi-Regge kinematics is presented. The main focus lies on the azimuthal angle dependences in events with two forward/backward jets tagged in the final state. Furthermore, the tagging of one or two extra jets in more central regions of the detector with a relative separation in rapidity from each other is requested. It is found that the dependence of the cross sections on the transverse momenta and the rapidities of the central jet(s) can offer new means of studying the onset of BFKL dynamics.A study of differential cross sections for the production of three and four jets in multi-Regge kinematics is presented. The main focus lies on the azimuthal angle dependences in events with two forward/backward jets tagged in the final state. Furthermore, the tagging of one or two extra jets in more central regions of the detector with a relative separation in rapidity from each other is requested. It is found that the dependence of the cross sections on the transverse momenta and the rapidities of the central jet(s) can offer new means of studying the onset of BFKL dynamics.

The Loop-Tree Duality: Progress Report

We review the recent developments of the Loop-Tree Duality method, focussing our discussion on the first numerical implementation and its use in the direct numerical computation of multi-leg Feynman integrals. Non-trivial examples are presented.