947 research outputs found
Generalized Gribov-Lipatov Reciprocity and AdS/CFT
Planar N=4 SYM theory and QCD share the gluon sector, suggesting the
investigation of Gribov-Lipatov reciprocity in the supersymmetric theory. Since
the AdS/CFT correspondence links N=4 SYM and superstring dynamics on AdS5xS5,
reciprocity is also expected to show up in the quantum corrected energies of
certain classical string configurations dual to gauge theory twist-operators.
We review recent results confirming this picture and revisiting the old idea of
Gribov-Lipatov reciprocity as a modern theoretical tool useful for the study of
open problems in AdS/CFT.Comment: 42 pages. Submitted to Advances in High Energy Physics, special issue
on the "Gauge/String duality
New Physics signals from measurable polarization asymmetries at LHC
We propose a new type of Z polarization asymmetry in bottom-Z production at
LHC that should be realistically measurable and would provide the determination
of the so-called parameter, whose available measured value still appears
to be in disagreement with the Standard Model prediction. This polarization can
be measured independently of a possible existence of Supersymmetry. If
Supersymmetry is found, a second polarization, i.e. the top longitudinal
polarization in top-charged Higgs production, would neatly identify the parameter. In this case, the value of should be in agreement with
the Standard Model. If Supersymmetry does not exist, a residual disagreement of
from the Standard Model prediction would be a clean signal of New Physics
of "non Supersymmetric" origin.Comment: typo correcte
Charged Higgs Production in the 1 TeV Domain as a Probe of Supersymmetric Models
We consider the production, at future lepton colliders, of charged Higgs
pairs in supersymmetric models. Assuming a relatively light SUSY scenario, and
working in the MSSM, we show that, for c.m. energies in the one TeV range, a
one-loop logarithmic Sudakov expansion that includes an "effective" next-to
subleading order term is adequate to the expected level of experimental
accuracy. We consider then the coefficient of the linear (subleading) SUSY
Sudakov logarithm and the SUSY next to subleading term of the expansion and
show that their dependence on the supersymmetric parameters of the model is
drastically different. In particular the coefficient of the SUSY logarithm is
only dependent on while the next to subleading term depends on a
larger set of SUSY parameters. This would allow to extract from the data
separate informations and tests of the model.Comment: 18 pages and 13 figures e-mail: [email protected]
The relevance of polarized bZ production at LHC
We consider the Z polarization asymmetry
A_Z=(sigma(Z_R)-sigma(Z_L))/(sigma(Z_R)+sigma(Z_L)) in the process of
associated bZ production at the LHC. We show that in the Standard Model (SM)
this quantity is essentially given by its Born approximation, remaining almost
unaffected by QCD scales and parton distribution functions variations as well
as by electroweak corrections. The theoretical quantity that appears in A_Z is
the same that provides the LEP1 Z -> b bbar forward-backward asymmetry, the
only measured observable still in some contradiction with the SM prediction. In
this sense, A_Z would provide the possibility of an independent verification of
the possible SM discrepancy, which could reach, if consistency with LEP1
measurements is imposed, values of the relative ten percent size.Comment: 10 pages, 5 eps figure
Weak Interaction Sum Rules for Polarized top-antitop Production at LHC
We consider two polarization asymmetries in the process of top-antitop
production at LHC. We show that the theoretical predictions for these two
quantities, at the strong and electroweak partonic one-loop level, are free of
QCD and QED effects. At this perturbative level we derive two sum rules, that
relate measurable quantities of top-antitop production to genuinely weak
inputs. This would allow to perform two independent tests of the candidate
theoretical model, with a precision that will be fixed by the future
experimental accuracies of the different polarization measurements. A tentative
quantitative illustration of this statement for a specific MSSM scenario is
enclosed, and a generalization to include two other future realistic
measurements is also proposed.Comment: 13 pages, 3 figures, local report number adde
Three loop anomalous dimensions of twist-3 gauge operators in N=4 SYM
We propose a closed expression for the three loop anomalous dimension of a
class of twist-3 operators built with gauge fields and covariant derivatives.
To this aim, we solve the long-range Bethe Ansatz equations at finite spin and
provide a consistent analytical formula obtained assuming maximal
transcendentality violation as suggested by the known one-loop anomalous
dimension. The final result reproduces the universal cusp anomalous dimension
and obeys recursion relations inspired by the principle of reciprocity
invariance.Comment: 20 pages, JHEP styl
QCD properties of twist operators in the N=6 Chern-Simons theory
We consider twist-1, 2 operators in planar N=6 superconformal Chern-Simons
ABJM theory. We derive higher order anomalous dimensions from integrability and
test various QCD-inspired predictions known to hold in N=4 SYM. In particular,
we show that the asymptotic anomalous dimensions display intriguing remnants of
Gribov-Lipatov reciprocity and Low-Burnett-Kroll logarithmic cancellations.
Wrapping effects are also discussed and shown to be subleading at large spin.Comment: 22 pages, expanded reference
Twist operators in N=4 beta-deformed theory
In this paper we derive both the leading order finite size corrections for
twist-2 and twist-3 operators and the next-to-leading order finite-size
correction for twist-2 operators in beta-deformed SYM theory. The obtained
results respect the principle of maximum transcendentality as well as
reciprocity. We also find that both wrapping corrections go to zero in the
large spin limit. Moreover, for twist-2 operators we studied the pole structure
and compared it against leading BFKL predictions.Comment: 17 pages; v2: minor changes, references adde
Twist-three at five loops, Bethe Ansatz and wrapping
We present a formula for the five-loop anomalous dimension of N=4 SYM
twist-three operators in the sl(2) sector. We obtain its asymptotic part from
the Bethe Ansatz and finite volume corrections from the generalized Luescher
formalism, considering scattering processes of spin chain magnons with virtual
particles that travel along the cylinder. The complete result respects the
expected large spin scaling properties and passes non-trivial tests including
reciprocity constraints. We analyze the pole structure and find agreement with
a conjectured resummation formula. In analogy with the twist-two anomalous
dimension at four-loops, wrapping effects are of order log^2 M/M^2 for large
values of the spin.Comment: 19 page
The relevance of virtual electroweak effects in the overall -channel single top production at LHC
We compute the complete one loop electroweak effects in the MSSM for the
eight processes of single top (and single antitop) production in the
-channel at hadron colliders, generalizing a previous analysis performed for
the dominant final state. The results are quite similar for all processes,
showing an impressively large Standard Model effect and a generally modest
genuine SUSY contribution in the mSUGRA scenario. The one loop effect on the
total rate is shown and the possibility of measuring it at LHC is discussed.Comment: 15 pages, 7 eps figure
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