A. Bassetto

Gauge invariance and anomalous dimensions of a light-cone Wilson loop in light-like axial gauge

Complete two-loop calculation of a dimensionally regularized Wilson loop with light-like segments is performed in the light-like axial gauge with the Mandelstam-Leibbrandt prescription for the gluon propagator. We find an expression which {\it exactly} coincides with the one previously obtained for the same Wilson loop in covariant Feynman gauge. The renormalization of Wilson loop is performed in the

On two-particle correlations in high energy production experiments

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Supersymmetric Wilson loops at two loops

scheme using a general procedure tailored to the light-like axial gauge. We find that the renormalized Wilson loop obeys a renormalization group equation with the same anomalous dimensions as in covariant gauges. Physical implications of our result for investigation of infrared asymptotics of perturbative QCD are pointed out.Complete two-loop calculation of a dimensionally regularized Wilson loop with light-like segments is performed in the light-like axial gauge with the Mandelstam-Leibbrandt prescription for the gluon propagator. We find an expression which exactly coincides with the one previously obtained for the same Wilson loop in covariant Feynman gauge. The renormalization of the Wilson loop is performed in the MS-scheme using a general procedure tailored to the light-like axial gauge. We find that the renormalized Wilson loop obeys a renormalization group equation with the same anomalous dimensions as in covariant gauges. Physical implications of our result for the investigation of infrared asymptotics of perturbative QCD are pointed out.

Correlators of supersymmetric Wilson-loops, protected operators and matrix models in N=4 SYM

One-particle and two-particle inclusive distributions are considered in the light of future production experiments at CERN Intersecting Storage Rings machine. We discuss the general properties of those models which are based on factorized approximations to the production amplitudes and are in agreement with some general hypotheses like the Feynman scaling law. First the role of phase space arguments is clarified and the importance of detecting correlations in high energy production experiments as an hint for understanding the underlying dynamics is emphasized. Then two peculiar (and, in a sense, complementary) kinds of correlation in two-particle inclusive distributions are examined: the one coming from multiperipheral dynamics with Lorentz pole exchanges, the other due to “direct channel” resonances. Some general properties of inclusive distributions are expressed in terms of quantities which are suitable for direct measurement.

Correlators of supersymmetric Wilson loops at weak and strong coupling

We study the quantum properties of certain BPS Wilson loops in = 4 supersymmetric Yang-Mills theory. They belong to a general family, introduced recently, in which the addition of particular scalar couplings endows generic loops on S3 with a fraction of supersymmetry. When restricted to S2, their quantum average has been further conjectured to be exactly computed by the matrix model governing the zero-instanton sector of YM2 on the sphere. We perform a complete two-loop analysis on a class of cusped Wilson loops lying on a two-dimensional sphere, finding perfect agreement with the conjecture. The perturbative computation reproduces the matrix-model expectation through a highly non-trivial interplay between ladder diagrams and self-energies/vertex contributions, suggesting the existence of a localization procedure.

Two-dimensional non-commutative Yang-Mills theory: coherent effects in open Wilson line correlators

We study the correlators of a recently discovered family of BPS Wilson loops in = 4 supersymmetric U(N) Yang-Mills theory. When the contours lie on a two-sphere in the space-time, we propose a closed expression that is valid for all values of the coupling constant g and for any rank N, by exploiting the suspected relation with two-dimensional gauge theories. We check this formula perturbatively at order (g4) for two latitude Wilson loops and we show that, in the limit where one of the loops shrinks to a point, logarithmic corrections in the shrinking radius are absent at (g6). This last result strongly supports the validity of our general expression and suggests the existence of a peculiar protected local operator arising in the OPE of the Wilson loop. At strong coupling we compare our result to the string dual of the = 4 SYM correlator in the limit of large separation, presenting some preliminary evidence for the agreement.

Perturbative Wilson loop in two-dimensional non-commutative Yang–Mills theory

We continue our study of the correlators of a recently discovered family of BPS Wilson loops in

On the unitarity of quantum gauge theories on non-commutative spaces

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