arXiv subjects

S. Digal

Publications and source records attributed to S. Digal.

21 records · Page 2Linked to original sources

arXiv2000

Cluster Percolation in O(n) Spin Models

The spontaneous symmetry breaking in the Ising model can be equivalently described in terms of percolation of Wolff clusters. In O(n) spin models similar clusters can be built in a general way, and they are currently used to update these systems in Monte Carlo simulations. We show that for 3-dimensional O(2), O(3) and O(4) such clusters are indeed the physical `islands' of the systems, i.e., they percolate at the physical threshold and the percolation exponents are in the universality class of the corresponding model. For O(2) and O(3) the result is proven analytically, for O(4) we derived it by numerical simulations.

hep-lat↗

arXiv2000

Deconfinement through Chiral Symmetry Restoration in Two-Flavour QCD

We propose that in QCD with dynamical quarks, colour deconfinement occurs when an external field induced by the chiral condensate strongly aligns the Polyakov loop. This effect sets in at the chiral symmetry restoration temperature T-chi and thus makes deconfinement and chiral symmetry restoration coincide. The predicted singular behaviour of Polyakov loop susceptibilities at T-chi is shown to be supported by finite temperature lattice calculations.

hep-ph↗

arXiv1999

Forming a Single, Large, DCC Domain in a Heavy-Ion Collision

We demonstrate the possibility of forming a single, large domain of disoriented chiral condensate (DCC) in a heavy-ion collision. In our scenario, rapid initial heating of the parton system provides a driving force for the chiral field, moving it away from the true vacuum and forcing it to go to the opposite point on the vacuum manifold. This converts the entire hot region into a single DCC domain. Subsequent rolling down of the chiral field to its true vacuum will then lead to emission of a large number of (approximately) coherent pions. The requirement of suppression of thermal fluctuations to maintain the (approximate) coherence of such a large DCC domain, favors three dimensional expansion of the plasma over the longitudinal expansion even at very early stages of evolution. This also constrains the maximum temperature of the system to lie within a window. We roughly estimate this window to be about 200 - 400 MeV. These results lead us to predict that extremely high energy collisions of {\it very small nuclei} (possibly hadrons) are better suited for observing signatures of a large DCC. Another possibility is to focus on {\it peripheral} collisions of heavy nuclei.

hep-ph↗