arXiv subjects

Antonio Bassetto

Publications and source records attributed to Antonio Bassetto.

4 recordsLinked to original sources

arXiv2011

Quantum 't Hooft loops of SYM N=4 as instantons of YM_2 in dual groups SU(N) and SU(N)/Z_N

A relation between circular 1/2 BPS 't Hooft operators in 4d N=4 SYM and instantonic solutions in 2d Yang-Mills theory (YM_2) has recently been conjectured. Localization indeed predicts that those 't Hooft operators in a theory with gauge group G are captured by instanton contributions to the partition function of YM_2, belonging to representations of the dual group ^LG. This conjecture has been tested in the case G=U(N)=^LG and for fundamental representations. In this paper we examine this conjecture in the case of the groups G=SU(N) and ^LG=SU(N)/Z_N and loops in different representations. Peculiarities when groups are not self-dual and representations not "minimal" are pointed out.

hep-th↗

arXiv2009

Correlators of supersymmetric Wilson loops at weak and strong coupling

We continue our study of the correlators of a recently discovered family of BPS Wilson loops in N=4 supersymmetric U(N) Yang-Mills theory. We perform explicit computations at weak coupling by means of analytical and numerical methods finding agreement with the exact formula derived from localization. In particular we check the localization prediction at order g^6 for different BPS "latitude" configurations, the N=4 perturbative expansion reproducing the expected results within a relative error of 10^(-4). On the strong coupling side we present a supergravity evaluation of the 1/8 BPS correlator in the limit of large separation, taking into account the exchange of all relevant modes between the string world-sheets. While reproducing the correct geometrical dependence, we find that the associated coefficient does not match the localization result.

hep-th↗

arXiv2008

Supersymmetric Wilson loops at two loops

We study the quantum properties of certain BPS Wilson loops in ${\cal N}=4$ supersymmetric Yang-Mills theory. They belong to a general family, introduced recently, in which the addition of particular scalar couplings endows generic loops on $S^3$ with a fraction of supersymmetry. When restricted to $S^2$, their quantum average has been further conjectured to be exactly computed by the matrix model governing the zero-instanton sector of YM$_2$ 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.

hep-th↗

arXiv2003

Planarity in Noncommutative Gauge Theories

Planarity was introduced by 't Hooft in his topological classification of diagrams in the large-N limit of U(N) gauge theories. Planarity also occurs in noncommutative field theories where amplitudes possess invariance only under cyclic permutations, a feature inherited from the parent string theory. In noncommutative gauge theories both kinds of planarity merge in a context which turns out to be particularly intriguing in the two-dimensional case where gauge invariant correlators can be explicitly computed.

hep-th↗