5,469 research outputs found
Critical Behavior of CP^1 at theta = pi, Haldane's Conjecture and the Universality Class
Using an approach to analyze the theta dependence of systems with a
theta-term we recently proposed, the critical behavior of CP^1 at theta=pi is
studied. We find a region outside the strong coupling regime where Haldane's
conjecture is verified. The critical line however does not belong to the
universality class of the Wess-Zumino-Novikov-Witten model at topological
coupling k=1 since it shows continuously varying critical exponents.Comment: 4 pages, 5 figure
Renormalization group and triviality in noncompact lattice QED with light fermions
In the framework of noncompact lattice QED with light fermions, we derive the
functional dependence of the average energy per plaquette on the bare
parameters using block-spin Renormalization Group arguments and assuming that
the renormalized coupling vanishes. Our numerical results for this quantity in
and lattices show evidence for triviality in the weak coupling
phase and point to a non vanishing value for the renormalized coupling constant
in the strong coupling phase.Comment: 9 page
Investigation of a Toy Model for Frustration in Abelian Lattice Gauge Theory
We introduce a lattice model with local U(1) gauge symmetry which
incorporates explicit frustration in d >2. The form of the action is inspired
from the loop expansion of the fermionic determinant in standard lattice QED.
We study through numerical simulations the phase diagram of the model,
revealing the existence of a frustrated (antiferromagnetic) phase for d=3 and
d=4, once an appropriate order parameter is identified.Comment: 7 pages, 7 figure
Obstructive sleep apnea syndrome in the pediatric age: the role of the dentist
Sleep disordered breathing in children designates a wide spectrum of respiratory disorders characterized by partial or complete obstruction of the upper airways. It ranges from primary snoring, its mildest clinical manifestation, to obstructive sleep apnea syndrome (OSAS): complete obstruction of the upper airways with cessation of airflow. The aim of this paper is to highlight the roles of the pediatric dentist and the orthodontist in the therapeutic approach to pediatric OSAS as a "sentinel" who can detect early signs of the disease for immediate referral to the otolaryngologist and as an active participant in therapy
Phase structure of a generalized Nambu Jona-Lasinio model with Wilson fermions in the mean field or large -expansion
We analyze the vacuum structure of a generalized lattice Nambu--Jona-Lasinio
model with two flavors of Wilson fermions, such that its continuum action is
the most general four-fermion action with 'trivial' color interactions, and
having a symmetry in the chiral limit. The phase structure
of this model in the space of the two four-fermion couplings shows, in addition
to the standard Aoki phases, new phases with , in
close analogy to similar results recently suggested by some of us for lattice
QCD with two degenerate Wilson fermions. This result shows how the phase
structure of an effective model for low energy QCD cannot be entirely
understood from Wilson Chiral Perturbation Theory, based on the standard QCD
chiral effective Lagrangian approach.Comment: 24 pages, 3 figures, sent to Nuclear Physics
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