A. Sabio Vera

Universidad Autónoma de Madrid, Madrid, Madrid, Spain

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Publications (93)177.38 Total impact

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    ABSTRACT: We complete the computation of the Mueller–Tang jet impact factor at next-to-leading order (NLO) initiated in [1] and presented in [2] by computing the real corrections associated to gluons in the initial state making use of Lipatov's effective action. NLO corrections for this effective vertex are an important ingredient for a reliable description of large rapidity gap phenomenology within the BFKL approach.
    Nuclear Physics B. 10/2014;
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    ABSTRACT: We present the calculation of the forward jet vertex associated to a rapidity gap (coupling of a hard pomeron to the jet) in the BFKL formalism at next-to-leading order (NLO). Real emission contributions are computed via Lipatov's effective action. The NLO jet vertex turns out to be finite within collinear factorization and allows, together with the NLO non-forward gluon Green's function, to perform NLO studies of jet production in diffractive events (e.g. Mueller-Tang dijets).
    09/2014;
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    ABSTRACT: We present the NLO corrections for the quark induced forward production of a jet with an associated rapidity gap. We make use of Lipatov's QCD high energy effective action to calculate the real emission contributions to the so-called Mueller-Tang impact factor. We combine them with the previously calculated virtual corrections and verify ultraviolet and collinear finiteness of the final result.
    Nuclear Physics B 06/2014; · 4.33 Impact Factor
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    ABSTRACT: We present the results for the calculation of the forward jet vertex associated to a rapidity gap (coupling of a hard pomeron to the jet) in the Balitsky-Fadin-Kuraev-Lipatov (BFKL) formalism at next-to-leading order (NLO). We handle the real emission contributions making use of the high energy effective action proposed by Lipatov, valid for multi-Regge and quasi-multi-Regge kinematics. This result is important since it allows, together with the NLO non-forward gluon Green function, to perform NLO studies of jet production in diffractive events (Mueller-Tang dijets, as a well-known example).
    Physics Letters B 04/2014; 735. · 4.57 Impact Factor
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    ABSTRACT: In this talk we review the work in [1,2,3] where we have studied the applicability of the color-kinematics duality to the scattering of two distinguishable scalar matter particles with one gluon emission in QCD, or one graviton emission in Einstein gravity. We have shown that the duality works well in the Regge limit under two different extensions of the gauge theory: the introduction of a new scalar contact interaction and the relaxation of the distinguishability of the scalars. Both modifications correspond to theories obtained by dimensional reduction from higher-dimensional pure gauge theories.
    10/2013;
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    ABSTRACT: We discuss aspects of our recent derivation of the gluon Regge trajectory at two loop from Lipatov's high energy effective action. We show how the gluon Regge trajectory can be rigorously defined through renormalization of the high energy divergence of the reggeized gluon propagator. We furthermore provide some details on the determination of the two-loop reggeized gluon self-energy.
    08/2013;
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    G. Chachamis, A. Sabio Vera
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    ABSTRACT: 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.
    07/2013;
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    ABSTRACT: We discuss computational details of our recent result, namely, the first derivation of the two-loop gluon Regge trajectory within the framework of Lipatov's high energy effective action. In particular, we elaborate on the direct evaluation of Feynman two-loop diagrams by using the Mellin-Barnes representations technique. Our result is in precise agreement with previous computations in the literature, providing this way a highly non-trivial test of the effective action and the proposed subtraction and renormalization scheme combined with our approach for the treatment of the loop diagrams.
    07/2013;
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    ABSTRACT: In this note we study the applicability of the color-kinematics duality to the scattering of two distinguishable scalar matter particles with gluon emission in QCD, or graviton emission in Einstein gravity. Previous analysis suggested that direct use of the Bern-Carrasco-Johansson double-copy prescription to matter amplitudes do not reproduce the gravitational amplitude in multi-Regge kinematics. However, minimal extensions of the calculation cure this obstacle. Here we present two approaches: introduction of a scalar contact interaction, or relaxing distinguishability of the scalars. In both cases new diagrams allow for a full reconstruction of the correct Regge limit on the gravitational side. Both modifications correspond to theories obtained by dimensional reduction from higher-dimensional gauge theories.
    07/2013;
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    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.
    Nuclear Physics B 07/2013; 876(2). · 4.33 Impact Factor
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    F. Caporale, B. Murdaca, A. Sabio Vera, C. Salas
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    ABSTRACT: We investigate the stability under variation of the renormalization, factorization and energy scales entering the calculation of the cross section, at next-to-leading order in the BFKL formalism, for the production of Mueller-Navelet jets at the Large Hadron Collider, following the experimental cuts on the tagged jets. To find optimal values for the scales involved in this observable it is possible to look for regions of minimal sensitivity to their variation. We show that the scales found with this logic are more natural, in the sense of being more similar to the squared transverse momenta of the tagged jets, when the BFKL kernel is improved with a resummation of collinear contributions than when the treatment is at a purely next-to-leading order. We also discuss the good perturbative convergence of the ratios of azimuthal angle correlations, which are quite insensitive to collinear resummations and well described by the original BFKL framework.
    Nuclear Physics B 05/2013; 875(1). · 4.33 Impact Factor
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    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 behaviour 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.
    Physics Letters B 05/2013; 724(s 1–3). · 4.57 Impact Factor
  • M. Hentschinski, Agustín S. Vera, Clara Salas
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    ABSTRACT: We show that it is possible to describe the effective Pomeron intercept, determined from the HERA Deep Inelastic Scattering data at small values of Bjorken x, using next-to-leading order BFKL evolution together with collinear improvements. To obtain a good description over the whole range of Q2 we use a non-Abelian physical renormalization scheme with BLM optimal scale, combined with a parametrization of the running coupling in the infrared region.
    04/2013;
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    Martin Hentschinski, Agustín Sabio Vera, Clara Salas
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    ABSTRACT: We show that it is possible to describe the effective Pomeron intercept, determined from the HERA deep inelastic scattering data at small values of Bjorken x, by using next-to-leading order Balitsky-Fadin-Kuraev-Lipatov evolution together with collinear improvements. To obtain a good description over the whole range of Q2, we use a non-Abelian physical renormalization scheme with the Brodsky-Lepage-Mackenzie optimal scale, combined with a parametrization of the running coupling in the infrared region.
    Physical Review Letters 01/2013; 110(4). · 7.73 Impact Factor
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    Martin Hentschinski, Agustin Sabio Vera, Clara Salas
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    ABSTRACT: We present a detailed description of the Q^2 and x dependence of the structure functions F2 and FL as extracted from the Deep Inelastic Scattering data at HERA in the small Bjorken x region. Making use of a collinearly-improved BFKL equation at next-to-leading order and a treatment of the running of the coupling using non-Abelian physical renormalization together with the BLM scale choice allows us to reach low values of Q^2. We also provide some predictions for future lepton-hadron colliders.
    Physical review D: Particles and fields 01/2013; 87(7).
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    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.
    Physical review D: Particles and fields 12/2012; 87(7).
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    ABSTRACT: We investigate tree-level five-point amplitudes in scalar-QCD expressed in terms of Sudakov variables and find the equivalent "gravitational" counterparts using the color-kinematics duality proposed by Bern, Carrasco, and Johannson. Taking the multi-Regge limit in the gravitational amplitudes, we show that those pieces in the coupling of two reggeized gravitons to one on-shell graviton directly stemming from the double copy of the vertex for two reggeized gluons to one on-shell gluon are universal and properly reproduced by the duality.
    Journal of High Energy Physics 12/2012; 2013(4). · 5.62 Impact Factor
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    G. Chachamis, A. Sabio Vera, C. Salas
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    ABSTRACT: Using Monte Carlo integration techniques, we investigate running coupling effects compatible with the high energy bootstrap condition to all orders in the strong coupling in evolution equations valid at small values of Bjorken x in deep inelastic scattering. A model for the running of the coupling with analytic behavior in the infrared region and compatible with power corrections to jet observables is used. As a difference to the fixed coupling case, where the momentum transfer acts as an effective strong cut-off of the diffusion to infrared scales, in our running coupling study the dependence on the momentum transfer is much milder.
    Physical review D: Particles and fields 11/2012; 87(1).
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    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.
    11/2012;
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    Jochen Bartels, Lev N. Lipatov, Agustin Sabio Vera
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    ABSTRACT: We study the interplay between graviton reggeization and double-logarithmic in energy contributions to four-graviton scattering in theories with and without supersymmetry. Predictions to all orders in the gravitational coupling are given for these double-logarithms. As the number of supersymmetries grows these terms generate a convergent behaviour for the amplitudes at very high energies. At two-loop level, we find agreement with previous exact results for N=8 supergravity and with those of Boucher-Veronneau and Dixon, who studied the N=4,5,6 supergravities using a conjectured double-copy structure of gravity.
    Journal of High Energy Physics 08/2012; · 5.62 Impact Factor

Publication Stats

714 Citations
177.38 Total Impact Points

Institutions

  • 2010–2014
    • Universidad Autónoma de Madrid
      • • Department of Theoretical physics
      • • Facultad de Ciencias
      Madrid, Madrid, Spain
  • 2000–2014
    • CERN
      • Physics Department (PH)
      Genève, Geneva, Switzerland
  • 2011
    • University of Florence
      Florens, Tuscany, Italy
  • 2005
    • University at Buffalo, The State University of New York
      • Department of Physics
      Buffalo, NY, United States
  • 2004–2005
    • University of Hamburg
      • II. Institut für Theoretische Physik
      Hamburg, Hamburg, Germany
  • 2000–2004
    • University of Cambridge
      • Department of Physics: Cavendish Laboratory
      Cambridge, ENG, United Kingdom
  • 1998–1999
    • The University of Manchester
      • School of Physics and Astronomy
      Manchester, England, United Kingdom