783 research outputs found
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
Four loop reciprocity of twist two operators in N=4 SYM
The four loop universal anomalous dimension of twist-2 operators in N=4 SYM
has been recently conjectured. In this paper, we prove that it obeys a
generalized Gribov-Lipatov reciprocity, previously known to hold at the three
loop level.Comment: 15 pages, v3: Appendix A.3 added, main body shortened, version
accepted in JHE
Large spin behavior of anomalous dimensions and short-long strings duality
We are considering the semi-classical string soliton solution of Gubser,
Klebanov and Polyakov which represents highly excited states on the leading
Regge trajectory, with large spin in . A prescription relates this
soliton solution with the corresponding field theory operators with many
covariant derivatives, whose anomalous scaling dimension grows logarithmically
with the space-time spin. We explicitly derive the dependence of anomalous
dimension on spin for all leading and next-to-leading orders at strong
coupling. We develop an iteration procedure which, in principle, allows to
derive all terms in the large spin expansion of the anomalous scaling dimension
of twist two operators. Our string theory results are consistent with the
conjectured "reciprocity" relation, which has been verified to hold in
perturbation theory up to five loops in N=4 SYM. We also derive a duality
relation between long and short strings.Comment: 15 pages, 1 figure, comments and references adde
Associated production of charged Higgs and top at LHC: the role of the complete electroweak supersymmetric contribution
The process of charged Higgs production in association with a top quark at
the LHC has been calculated at the complete NLO electroweak level both in a Two
Higgs Doublets Model and in the Minimal Supersymmetric Standard Model, assuming
a mSUGRA breaking scheme. We have numerically explored the size of the one-loop
corrections in two typical supersymmetric scenarios, with particular attention
to the tan beta dependence, and we have found that they remain perturbatively
small but possibly sizable, reaching a 20% limit for extreme values of tan
beta, when the complete set of Feynman diagrams is taken into account.Comment: 22 pages, 5 figures, reference adde
Supersymmetry spectroscopy in stop-chargino production at LHC
We consider the process of associated stop-chargino production in the MSSM at
LHC and show that, at the simplest Born level, the production rate is
dramatically sensitive to the choice of the benchmark points, oscillating from
potentially "visible" maxima of the picobarn size to much smaller, hardly
"visible", values. Adopting a canonical choice of SM type CKM matrices, we also
show that in some "visible" cases the total rate exhibits a possibly relevant
dependence on tan(beta).Comment: 23 pages, 18 eps figure
The role of universal and non universal Sudakov logarithms in four fermion processes at TeV energies: the one-loop approximation revisited
We consider the separate effects on four fermion processes, in the TeV energy
range, produced at one loop by Sudakov logarithms of universal and not
universal kind, working in the 't Hooft xi=1 gauge. Summing the various vertex
and box contributions allows to isolate two quite different terms.The first one
is a combination of vertex and box quadratic and linear logarithms that are
partially universal and partially not universal and independent of the
scattering angle theta. The second one is theta-dependent, not universal,
linearly logarithmic and only produced by weak boxes. We show that for several
observables, measurable at future linear e+e- colliders (LC, CLIC), the role of
the latter term is dominant and we discuss the implications of this fact for
what concerns the reliability of a one-loop approximation.Comment: 22 pages and 13 figures; version to appear in Phys.Rev.D. e-mail:
[email protected]
Supersymmetry breaking in two dimensions: the lattice N=1 Wess-Zumino model
We study dynamical supersymmetry breaking by non perturbative lattice
techniques in a class of two-dimensional N=1 Wess-Zumino models. We work in the
Hamiltonian formalism and analyze the phase diagram by analytical
strong-coupling expansions and explicit numerical simulations with Green
Function Monte Carlo methods.Comment: 53 pages, 17 figures, revtex
Anomalous dimensions of finite size field strength operators in N=4 SYM
In the N=4 super Yang-Mills theory, we consider the higher order anomalous
dimensions gamma_L(g) of purely gluonic operators Tr(F^L) where F is a
component of the self-dual field strength. We propose compact closed
expressions depending parametrically on L that reproduce the prediction of
Bethe Ansatz equations up to five loop order, including transcendental dressing
corrections. The size dependence follows a simple pattern as the perturbative
order is increased and suggests hidden relations for these special operators.Comment: 26 pages, 3 eps figures. v2: published version, minor changes,
references adde
D0-brane tension in string field theory
We compute the D0-brane tension in string field theory by representing it as
a tachyon lump of the D1-brane compactified on a circle of radius . To this
aim, we calculate the lump solution in level truncation up to level L=8. The
normalized D0-brane tension is independent on . The compactification radius
is therefore chosen in order to cancel the subleading correction . We
show that an optimal radius indeed exists and that at the
theoretical prediction for the tension is reproduced at the level of .
As a byproduct of our calculation we also discuss the determination of the
marginal tachyon field at .Comment: 13 pages, 3 Eps figure
Wrapping corrections, reciprocity and BFKL beyond the sl(2) subsector in N=4 SYM
We consider N=4 SYM and a class of spin N, length-3, twist operators beyond
the well studied sl(2) subsector. They can be identified at one-loop with three
gluon operators. At strong coupling, they are associated with spinning strings
with two spins in AdS5. We exploit the Y-system to compute the leading
weak-coupling four loop wrapping correction to their anomalous dimension. The
result is written in closed form as a function of the spin N. We combine the
wrapping correction with the known four-loop asymptotic Bethe Ansatz
contribution and analyze special limits in the spin N. In particular, at large
N, we prove that a generalized Gribov-Lipatov reciprocity holds. At negative
unphysical spin, we present a simple BFKL-like equation predicting the
rightmost leading poles.Comment: 18 page
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