1,605 research outputs found
A Solution to the 4-tachyon off-shell amplitude in cubic string field theory
No full textWe derive an analytic series solution of the elliptic equations providing the 4-tachyon off-shell amplitude in cubic string field theory (CSFT). From such a solution we compute the exact coefficient of the quartic effective action relevant for time dependent solutions and we derive the exact coefficient of the quartic tachyon coupling. The rolling tachyon solution expressed as a series of exponentials et is studied both using level-truncation computations and the exact 4-tachyon amplitude. The results for the level truncated coefficients are shown to converge to those derived using the exact string amplitude. The agreement with previous work on the subject, both on the quartic tachyon coupling and on the CSFT rolling tachyon, is an excellent test for the accuracy of our off-shell solution
A NEW ROLLING TACHYON SOLUTION OF CUBIC STRING FIELD THEORY
No full textWe present a new analytic time dependent solution of cubic string field theory at the lowest order in the level truncation scheme. The tachyon profile we have found is a bounce in time, a C∞ function which represents an almost exact solution, with an extremely good degree of accuracy, of the classical equations of motion of the truncated string field theory. Such a finite energy solution describes a tachyon which at x0 = −∞ is at the maximum of the potential, at later times rolls toward the stable minimum and then up to the other side of the potential toward the inversion point and then back to the unstable maximum for x0 → +∞. The energy-momentum tensor associated with this rolling tachyon solution can be explicitly computed. The energy density is constant, the pressure is an even function of time which can change sign while the tachyon rolls toward the minimum of its potential. A new form of tachyon matter is realized which might be relevant for cosmological applications
Four loop reciprocity of twist two operators in N=4 SYM
No full textThe complete universal anomalous dimension of twist-2 operators in N=4 SYM has been recently conjectured at four loops in terms of maximum transcendentality combinations of harmonic sums. It reproduces the known cusp anomaly, NLO BFKL poles, and the diagrammatic result for the Konishi operator. In this paper, we prove that it passes a further deep test related to a generalized Gribov-Lipatov reciprocity. This holds for both the asymptotic Bethe Ansatz contribution and the novel wrapping correction. This result suggests reciprocity to be a very stable and intrinsic property of twist-2 operators
EXACT POTENTIAL AND SCATTERING AMPLITUDES FROM THE TACHYON NONLINEAR BETA FUNCTION
No full textWe compute, on the disk, the non-linear tachyon β-function, β T , of the open bosonic string theory. β T is determined both in an expansion to the third power of the field and to all orders in derivatives and in an expansion to any power of the tachyon field in the leading order in derivatives. We construct the Witten-Shatashvili (WS) space-time effective action S and prove that it has a very simple universal form in terms of the renormalized tachyon field and β T . The expression for S is well suited to studying both processes that are far off-shell, such as tachyon condensation, and close to the mass-shell, such as perturbative on-shell amplitudes. We evaluate S in a small derivative expansion, providing the exact tachyon potential. The normalization of S is fixed by requiring that the field redefinition that maps S into the tachyon effective action derived from the cubic string field theory is regular on-shell. The normalization factor is in precise agreement with the one required for verifying all the conjectures on tachyon condensation. The coordinates in the space of couplings in which the tachyon β-function is non linear are the most appropriate to study RG fixed points that can be interpreted as solitons of S, i.e. D-branes
Qcd-like properties of anomalous dimensions in the NN =4 supersymmetric Yang-Mills theory
No full textWe show how closed formulas for the anomalous dimensions of two classes of operators in the =4 supersymmetric Yang-Mills theory can be derived either based on numerical investigation or based on QCD-inspired assumptions. We consider the case of twist-3 “gauge” operators for which we completely prove the reciprocity
Gauge invariant finite size spectrum of the giant magnon
No full textIt is shown that the finite size corrections to the spectrum of the giant magnon solution of classical string theory, computed using the uniform light-cone gauge, are gauge invariant and have physical meaning. This is seen in two ways: from a general argument where the single magnon is made gauge invariant by putting it on an orbifold as a wrapped state obeying the level matching condition as well as all other constraints, and by an explicit calculation where it is shown that physical quantum numbers do not depend on the uniform light-cone gauge parameter. The resulting finite size effects are exponentially small in the R-charge and the exponent (but not the prefactor) agrees with gauge theory computations using the integrable Hubbard model
Finite size corrections and integrability of N=2 SYM and DLCQ strings on a pp-wave
No full textWe compute the planar finite size corrections to the spectrum of the dilatation operator acting on two-impurity states of a certain limit of conformal Script N = 2 quiver gauge field theory which is a ZM-orbifold of Script N = 4 supersymmetric Yang-Mills theory. We match the result to the string dual, IIB superstrings propagating on a pp-wave background with a periodically identified null coordinate. Up to two loops, we show that the computation of operator dimensions, using an effective Hamiltonian technique derived from renormalized perturbation theory and a twisted Bethe ansatz which is a simple generalization of the Beisert-Dippel-Staudacher [1] long range spin chain, agree with each other and also agree with a computation of the analogous quantity in the string theory. We compute the spectrum at three loop order using the twisted Bethe ansatz and find a disagreement with the string spectrum very similar to the known one in the near BMN limit of Script N = 4 super-Yang-Mills theory. We show that, like in Script N = 4, this disagreement can be resolved by adding a conjectured ``dressing factor'' to the twisted Bethe ansatz. Our results are consistent with integrability of the Script N = 2 theory within the same framework as that of Script N = 4
Reciprocity of gauge operators in N=4SYM
No full textA recently discovered generalized Gribov-Lipatov reciprocity holds for the anomalous dimensions of various twist operators in Script N = 4 SYM. Here, we consider a class of scaling operators that reduce at one-loop to twist-3 maximal helicity gluonic operators. We extract from the asymptotic long-range Bethe Ansatz a closed expression for the spin dependent anomalous dimension at four loop order and provide a complete proof of reciprocity. We comment about the interplay with possible, yet unknown, wrapping corrections
Schermi. Immagini, corpi, condivisioni
No full textIn this book the author investigates the digital image proliferation of our times from an interdisciplinary point of view. Starting from the Visual Culture theoretical frame, Valentina Mignano explores the ways in which we interact with the screen, dealing with the "screen experience" in the first years of the network societ
Generalized Gribov-Lipatov Reciprocity and AdS/CFT
No full textPlanar
=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
=4
SYM and superstring dynamics on
Ad
S
5
×
S
5
, 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
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