844 research outputs found
Double-logarithms in Einstein-Hilbert gravity and supergravity
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
High Energy Behavior of a Six-Point R-Current Correlator in N=4 Supersymmetric Yang-Mills Theory
We study the high energy limit of a six-point R-current correlator in N=4
supersymmetric Yang-Mills theory for finite N_c. We make use of the framework
of perturbative resummation of large logarithms of the energy. More
specifically, we apply the (extended) generalized leading logarithmic
approximation. We find that the same conformally invariant two-to-four gluon
vertex occurs as in non-supersymmetric Yang-Mills theory. As a new feature we
find a direct coupling of the four-gluon t-channel state to the R-current
impact factor.Comment: 47 page
Analytic structure of the scattering amplitude in SYM theory at multi-Regge kinematics: Conformal Regge pole contribution
We investigate the analytic structure of the scattering amplitude in
the planar limit of SYM in multi-Regge kinematics in all
physical regions. We demonstrate the close connection between Regge pole and
Regge cut contributions: in a selected class of kinematic regions (Mandelstam
regions) the usual factorizing Regge pole formula develops unphysical
singularities which have to be absorbed and compensated by Regge cut
contributions. This leads, in the corrections to the BDS formula, to conformal
invariant 'renormalized' Regge pole expressions in the remainder function. We
compute these renormalized Regge poles for the scattering amplitude.Comment: 46 pages, references added, typos corrected, journal versio
Effect of the Charm Quark Mass on the BFKL gamma^* gamma^* Total Cross Section at LEP
We perform a numerical study of various improvements of the LO BFKL
prediction for the gamma^* gamma^* total cross section in the kinematical
region of the L3 detector at LEP. In particular, we study the effects of a
massive charm quark and of different photon polarizations. The variation of the
BFKL prediction under changes of alpha_s is investigated.Comment: 10 pages, 6 figure
Analytic structure of the scattering amplitude in SYM theory in multi-Regge kinematics: Conformal Regge cut contribution
In this second part of our investigation of the analytic structure of the
scattering amplitude in the planar limit of SYM in
multi-Regge kinematics we compute, in all kinematic regions, the Regge cut
contributions in leading order. The results are infrared finite and conformally
invariant.Comment: 44 pages, 14 figures, 2 table
- …