arXiv subjects

Ferdinando Gliozzi

Publications and source records attributed to Ferdinando Gliozzi.

At least 37 records · Page 2Linked to original sources

arXiv2008

Confining string beyond the free approximation: the case of random percolation

The random percolation model can be viewed as the dual of a well defined confining gauge theory; since this theory, having no Monte Carlo dynamics at all, is simple to simulate, it is possible to study the properties of the flux tube with very high precision; we show it can be described by the effective string picture. Our results are lattice regularisation independent, therefore they are well defined also in the continuum limit, and, for the first time in a gauge theory, it has been possible to determine the next-to-leading quantum corrections throughout the computation of the T^6 coefficient of the Taylor expansion of sigma(T). Furthermore, this coefficient results to be related to the universal ratio T_c/\sqrt{sigma_0}.

hep-lat↗

arXiv2008

The monopole mass in the random percolation gauge theory

We study the behaviour of the monopole at finite temperature in the (2+1)-dimensional lattice gauge theory dual to the percolation model; by exploiting the correspondences to statistical systems, we possess powerful tools to evaluate the monopole mass both above and below the critical temperature with high-precision Monte Carlo simulations.

hep-lat↗

arXiv2008

On the ODE/IM correspondence for minimal models

Within the framework of the ODE/IM correspondence, we show that the minimal conformal field theories with c<1 emerge naturally from the monodromy properties of certain families of ordinary differential equations.

hep-th↗

arXiv2007

K-string tensions at finite temperature and integrable models

It has recently been pointed out that simple scaling properties of Polyakov correlation functions of gauge systems in the confining phase suggest that the ratios of k-string tensions in the low temperature region is constant up to terms of order T^3. Here we argue that, at least in a three-dimensional Z_4 gauge model, the above ratios are constant in the whole confining phase. This result is obtained by combining numerical experiments with known exact results on the mass spectrum of an integrable two-dimensional spin model describing the infrared behaviour of the gauge system near the deconfining transition.

hep-lat↗

arXiv2007

On the conformal anomaly of k-strings

We discuss the long distance behaviour of the flux tube associated to baryon vertices and argue that, if the gauge system admits stable k-strings, the conformal field theory describing this string in the IR has conformal anomaly c=(d-2)σ_k/σ, where σ_k is the k-string tension and σthat of the fundamental representation. We check this result in a 3D Z_4 gauge model at finite temperature, where a string effect directly related to "c" can be clearly identified.

hep-lat↗

arXiv2007

Universal properties of the confining string in the random percolation model

Random percolation can be fully interpreted as a confining pure gauge theory. With numerical high-precision measurements of Polyakov-Polyakov correlators at finite temperature, we could well observe the presence of shape effects due to rough fluctuations of the confining string, in complete agreement with the universality predictions up to the next-to-leading order.

hep-lat↗

arXiv2007

The conformal anomaly of k-strings

Simple scaling properties of correlation functions of a confining gauge theory in d-dimensions lead to the conclusion that k-string dynamics is described, in the infrared limit, by a two-dimensional conformal field theory with conformal anomaly c=(d-2)T_k/T_1, where T_k is the k-string tension. This result applies to any gauge theory with stable k-strings. We check it in a 3D Z_4 gauge model at finite temperature, where a string effect directly related to c can be clearly identified.

hep-th↗

arXiv2006

Quantum broadening of k-strings in gauge theories

We study the thickness of the confining flux tube generated by a pair of sources in higher representations of the gauge group. Using a simple geometric picture we argue that the area of the cross-section of the flux tube, as measured by a Wilson loop probe, grows logarithmically with source separation, as a consequence of the quantum fluctuations of the underlying k-string. The slope of the logarithm turns out to be universal, i.e. it is the same for all the representations and all the gauge theories. We check these predictions in a 3D Z_4 lattice gauge model by comparing the broadening of the 1-string and the 2-string.

hep-th↗

arXiv2006

Broadening of the confining flux tube joining higher-representation sources

In the context of confining gauge theories we study the flux tube generated by a pair of static sources belonging to higher rank representations of the gauge group. Using a simple geometric approach based on minimal surfaces describing the world-sheet of the underlying k-string, we infer logarithmic broadening of the flux tube as a function of source separation. It turns out that the coefficient of the logarithm does not depend on the specific representation of the source nor on its N-ality and is universal. Numerical results on a Z_4 gauge theory in three dimensions with static sources carrying two units of elementary flux compare very favourably with these predictions.

hep-lat↗

arXiv2006

Quantum fluctuations of k-strings: A case study

K strings in Yang-Mills theory can be considered as bound states of k elementary confining strings carrying one unit of colour flux. Current estimates of k-string tension sigma_k are very sensitive to the leading corrections due to quantum fluctuations of the string. In this study we address this problem by comparing Polyakov-Polyakov correlators in the fundamental representation (k=1) with the corresponding ones with k=2 in the confining phase of a Z_4 gauge theory in three dimensions. Highly efficient simulation techniques are available in this case. Although the k=1 Polyakov-Polyakov correlator matches nicely with the expected bosonic string effects up to the Next-to-Leading-Order, the k=2 Polyakov-Polyakov correlators show large deviations. This is an important source of potential systematic errors in the current estimates of sigma_k.

hep-lat↗

arXiv2006

Critical exponents for higher-representation sources in 3D SU(3) gauge theory from CFT

We establish an exact mapping between the multiplication table of the irreducible representations of SU(3) and the fusion algebra of the two-dimensional conformal field theory in the same universality class of 3D SU(3) gauge theory at the deconfining point. In this way the Svetitsky-Yaffe conjecture on the critical behaviour of Polyakov lines in the fundamental representation naturally extends to whatever representation one considers. As a consequence, the critical exponents of the correlators of these Polyakov lines are determined. Monte Carlo simulations with sources in the symmetric two-index representation, combined with finite-size scaling analysis, compare very favourably with these predictions.

hep-th↗

arXiv2006

Where is the confining string in random percolation

The percolating phase of whatever random percolation process resembles the confining vacuum of a gauge theory in most respects, with a string tension having a well-behaved continuum limit, a non trivial glueball spectrum and a deconfinement transition at a well determined temperature T_c. Simple numerical experiments reveal an underlying, strongly fluctuating, confining string, with an internal vortex structure formed by a core trapping inside a Coulomb-like phase composed by the vacuum at the percolation threshold. The width of the core almost coincides with 1/T_c and it turns out to be separated form the confining vacuum by a domain wall of definite thickness.

hep-lat↗

arXiv2005

The glue-ball spectrum of pure percolation

We present a high-precision numerical study of 3D random percolation viewed as a confining gauge theory. Using large correlation matrices among multiform Wilson loops we determine the low-lying masses in various spin channels.

hep-lat↗

arXiv2005

The decay of unstable k-strings in SU(N) gauge theories at zero and finite temperature

Sources in higher representations of SU(N) gauge theory at T=0 couple with apparently stable strings with tensions depending on the specific representation rather than on its N-ality. Similarly at the deconfining temperature these sources carry their own representation-dependent critical exponents. It is pointed out that in some instances one can evaluate exactly these exponents by fully exploiting the correspondence between the 2+1 dimensional critical gauge theory and the 2d conformal field theory in the same universality class. The emerging functional form of the Polyakov-line correlators suggests a similar form for Wilson loops in higher representations which helps in understanding the behaviour of unstable strings at T=0. A generalised Wilson loop in which along part of its trajectory a source is converted in a gauge invariant way into higher representations with same N-ality could be used as a tool to estimate the decay scale of the unstable strings.

hep-th↗

arXiv2005

k-strings and baryon vertices in SU(N) gauge theories

It is pointed out that the sine law for the k-string tension emerges as the critical threshold below which the spatial Z_N symmetry of the static baryon potential is spontaneously broken. This result applies not only to SU(N) gauge theories, but to any gauge system with stable k-strings admitting a baryon vertex made with N sources in the fundamental representation. Some simple examples are worked out.

hep-th↗

arXiv2003

Confinement-deconfinement and universal string effects from random percolation

The 't Hooft criterion leading to confinement out of a percolating cluster of central vortices suggests defining a novel three-dimensional gauge theory directly on a random percolation process. Wilson loop is viewed as a counter of topological linking with the random clusters. Beyond the percolation threshold large Wilson loops decay with an area law and show the universal shape effects due to flux tube fluctuations. Wilson loop correlators define a non-trivial glueball spectrum. The crumbling of the percolating cluster when one periodic direction narrows accounts for the finite temperature deconfinement, which belongs to 2D percolation universality class.

hep-lat↗

arXiv2002

The phase diagram of the three-dimensional Z2 gauge Higgs system at zero and finite temperature

We study the effect of adding a matter field to the Z2 gauge model in three dimensions at zero and finite temperature. Up to a given value of the parameter regulating the coupling, the matter field produces a slight shift of the transition line without changing the universality class of the pure gauge theory, as seen by finite size scaling analysis or by comparison, in the finite temperature case, to exact formulas of conformal field theory. At zero temperature the critical line turns into a first-order transition. The fate of this kind of transition in the finite temperature case is discussed.

hep-lat↗

arXiv2002

Simulation of Potts models with real q and no critical slowing down

A Monte Carlo algorithm is proposed to simulate ferromagnetic q-state Potts model for any real q>0. A single update is a random sequence of disordering and deterministic moves, one for each link of the lattice. A disordering move attributes a random value to the link, regardless of the state of the system, while in a deterministic move this value is a state function. The relative frequency of these moves depends on the two parameters q and beta. The algorithm is not affected by critical slowing down and the dynamical critical exponent z is exactly vanishing. We simulate in this way a 3D Potts model in the range 2<q<3 for estimating the critical value q_c where the thermal transition changes from second-order to first-order, and find q_c=2.620(5).

cond-mat.stat-mech↗