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Chachamis, G., Hentschinski, M., Madrigal Martinez, J. D., & Sabio Vera, A. (2013). Next-to-leading order corrections to the gluon-induced forward jet vertex from the high energy effective action. Phys. Rev. D, 87(7), 076009–11pp.
Abstract: We determine both real and virtual next-to-leading order corrections to the gluon-induced forward jet vertex from the high energy effective action proposed by Lipatov. For these calculations we employ the same regularization and subtraction formalism developed in our previous work on the quark-initiated vertex. We find agreement with previous results in the literature.
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Caporale, F., Chachamis, G., Madrigal, J. D., Murdaca, B., & Sabio Vera, A. (2013). A study of the diffusion pattern in N=4 SYM at high energies. Phys. Lett. B, 724(1-3), 127–132.
Abstract: In the context of evolution equations and scattering amplitudes in the high energy limit of the N = 4 super Yang-Mills theory we investigate in some detail the BFKL gluon Green function at next-to-leading order. In particular, we study its collinear behavior in terms of an expansion in different angular components. We also perform a Monte Carlo simulation of the different final states contributing to such a Green function and construct the diffusion pattern into infrared and ultraviolet modes and multiplicity distributions, making emphasis in separating the gluon contributions from those of scalars and gluinos. We find that the combined role of the non-gluonic degrees of freedom is to improve the collinear behavior and reduce the diffusion into ultraviolet regions while not having any effect on the average multiplicities or diffusion into the infrared. In terms of growth with energy, the non-zero conformal spin components are mainly driven by the gluon terms in the BFKL kernel. For zero conformal spin (Pomeron) the effect of the scalar and gluino sectors is to dramatically push the Green function towards higher values.
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Chachamis, G., Hentschinski, M., Madrigal Martinez, J. D., & Sabio Vera, A. (2013). Gluon Regge trajectory at two loops from Lipatov's high energy effective action. Nucl. Phys. B, 876(2), 453–472.
Abstract: We present the derivation of the two-loop gluon Regge trajectory using Lipatov's high energy effective action and a direct evaluation of Feynman diagrams. Using a gauge invariant regularization of high energy divergences by deforming the light-cone vectors of the effective action, we determine the two-loop self-energy of the reggeized gluon, after computing the master integrals involved using the Mellin-Barnes representations technique. The self-energy is further matched to QCD through a recently proposed subtraction prescription. The Regge trajectory of the gluon is then defined through renormalization of the reggeized gluon propagator with respect to high energy divergences. Our result is in agreement with previous computations in the literature, providing a non-trivial test of the effective action and the proposed subtraction and renormalization framework.
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Chachamis, G., Hentschinski, M., Madrigal Martinez, J. D., & Sabio Vera, A. (2014). Forward jet production and quantum corrections to the gluon Regge trajectory from Lipatov's high energy effective action. Phys. Part. Nuclei, 45(4), 788–799.
Abstract: We review Lipatov's high energy effective action and show that it is a useful computational tool to calculate scattering amplitudes in (quasi)-multi-Regge kinematics. We explain in some detail our recent work where a novel regularization and subtraction procedure has been proposed that allows to extend the use of this effective action beyond tree level. Two examples are calculated at next-to-leading order: forward jet vertices and the gluon Regge trajectory.
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Buchta, S., Chachamis, G., Draggiotis, P., Malamos, I., & Rodrigo, G. (2014). On the singular behaviour of scattering amplitudes in quantum field theory. J. High Energy Phys., 11(11), 014–13pp.
Abstract: We 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.
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