1,720,980 research outputs found
On the behaviour of the interquark potential in the vicinity of the deconfinement transition
No full textTwo-loop coupling constant renormalization in lattice SU(N)×SU(N) 2 D chiral models
No full textFor the most general link action of lattice SU(N)×SU(N) two dimensional chiral models, the two loop coupling constant renormalization is discussed in the context of the background field method. A non-linear reparametrization of the fields, necessary to keep the invariance of the theory, introduces unpleasant extra-terms. However some of the non-universal contributions are unaffected by these extra-terms and can be easily calculated. This allows to compute the difference between the first non-universal coefficients of the Callan-Symanzik beta function for two actions having the same scale Λ. © 1986 Springer-Verlag
Phase transitions in lattice 2 D O(N)σ-model with mixed action in the large N limit
No full textWe study the exact N→∞ solution of the two-dimensional lattice o(N) σ-model, described by a two parameter action that mixes Wilson (quadratic) and RPN-1≈O(N)/Z2 (quartic) actions. A rich phase structure emerges, with a first order transition line crossing, in the two-dimensional parameter space the RPN-1 axis. At the end of this line the specific-heat diverges while the correlation length remains finite. © 1987 Springer-Verlag
Level-Crossing in the Instanton-Anti-Instanton Valley
No full textWe study the level crossing of the fermion system described by the euclidean
Dirac Hamiltonian in the valley background.
One chiral fermion level is shown to cross twice the zero value in the case
of well-separated instanton-anti-instanton background.
Below a critical separation, however, level crossings are absent. The
phenomenon can be interpreted as the transition to a gauge field configuration
of purely perturbative nature, below a critical instanton-anti-instanton
separation. In the context of high-energy electroweak interactions, our
findings seem to definitely invalidate some optimistic argument concerning the
observability of baryon number violation based on the use of the optical
theorem in conjunction with the valley fields
Quasiparticle agglomerates in the Read-Rezayi and anti-Read-Rezayi states
No full textWe calculate the dominant excitations for the k-level () Read-Rezayi (RR) states and their particle-hole conjugates, the anti-Read-Rezayi (), proposed for quantum Hall states. These states are supposed to be built over the second Landau level with total filling factor ν=2+ν* with ν*=k/(k+2) for RR and ν*=2/(k+2) for . In the k-level RR states, based on parafermions, the dominant excitations are the fundamental quasiparticles (qps) with fractional charge e*k=e/(k+2), with e the electron charge, if k=2,3. For k=4 the single-qp and the 2-agglomerate, with charge 2e*k, have the same scaling and both dominate, while for k>4 the 2-agglomerates are dominant. Anyway the dominance of the 2-agglomerates can be affected by the presence of environmental renormalizations. For all the k-level states, the single-qp and the 2-agglomerate have the same scaling and both dominate. In this case, only the presence of environmental renormalizations can make one dominant over the other. We determine the conditions in which the environmental renormalizations of the charged and neutral modes make the Abelian 2-agglomerates dominant over the non-Abelian single-qps in the two models and for any value of k. We conclude by observing that, according to these predictions, the dominance of 2-agglomerates, at very low energies for the ν=5/2, can be an interesting indication supporting the validity of the anti-Pfaffian model in comparison with the Pfaffian. © 2012 The Royal Swedish Academy of Sciences
FERMIONS, ANOMALY AND UNITARITY IN HIGH-ENERGY ELECTROWEAK INTERACTIONS
No full textWe report on the ''state of the art'' of the problem of B + L violation in high energy electroweak scatterings. Results of various analyses point to (but do not prove rigorously yet) ''half-suppression,'' i.e. the (B + L)-violating cross section remains suppressed at least by the negative exponent of the single instanton action, at all energies. The most interesting techniques developed in this field are reviewed. Particular attention is paid to unitarity constraints on the anomalous cross section, and to some conceptual problems involving the use of the optical theorem in the presence of instantons
GENERATION OF MASS HIERARCHIES AND GRAVITATIONAL INSTANTON-INDUCED SUPERSYMMETRY BREAKING
No full textOn the Beta Function in Supersymmetric Gauge Theories
No full textWe re-examine perturbative and nonperturbative aspects of the beta function
in N=1 and N=2 supersymmetric gauge theories, make comments on the recent
literature on the subject and discuss the exactness of several known results
such as the NSVZ beta function
Magneto-thermal transport implies an incoherent Hall conductivity
No full textWe consider magnetohydrodynamics with an external magnetic field. We find that in general one must allow for a non-zero incoherent Hall conductivity to correctly describe the DC longitudinal and Hall thermal conductivities beyond order zero in the magnetic field expansion. We apply our result to the dyonic black hole, determining the incoherent Hall conductivity in that case, and additionally prove that the existence of this transport coefficient leads to a significantly better match between the hydrodynamic and AC thermo-electric correlators
Energy trapped Ising model
No full textIn this paper we have considered the 3D Ising model perturbed with the energy operator coupled with a non uniform harmonic potential acting as a trap, showing that this system satisfies the trap-size scaling behavior. Eventually, we have computed the correlators ⟨σ(z)σ(0)⟩, ⟨ε(z)ε(0)⟩ and ⟨σ(z)ε(0)⟩ near the critical point by means of conformal perturbation theory. Combining this result with Monte Carlo simulations, we have been able to estimate the OPE coefficients Cσσε, Cεσσ and Cεεε, finding a good agreement with the values obtained in [1,2]
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