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Saumen Datta

Publications and source records attributed to Saumen Datta.

46 records · Page 3Linked to original sources
arXiv1999

Impact of Z_2 monopoles and vortices on the deconfinement transition

The impact of Z_2-monopoles and vortices on the bulk and the deconfinement phase transitions of the SU(2) lattice gauge theory with a mixed Villain form of action is investigated by varying their numbers with appropriate chemical potentials. Suppressing the former shifts the line of deconfinement transitions in the coupling plane but it continues to behave also like the bulk transition line. We find separate deconfinement and bulk phase transitions on the same lattice, suggesting the two to be indeed coincident at higher adjoint couplings. Universality is restored when both monopoles and vortices are suppressed.

hep-lat↗
arXiv1999

Screening Masses in SU(2) Pure Gauge Theory

We perform a systematic scaling study of screening masses in pure gauge SU(2) theory at temperatures above the phase transition temperature. The major finite volume effect is seen to be spatial deconfinement. We extract the screening masses in the infinite volume and zero lattice spacing limit. We find that these physical results can be deduced from runs on rather coarse lattices. Dimensional reduction is clearly seen in the spectrum.

hep-lat↗
arXiv1999

The Deconfinement Transition in SO(3) Gauge Theory

The SO(3) lattice gauge theory with a Villain form of action was investigated by Monte Carlo techniques on asymmetric lattices with Nt = 2 and 4, where Nt is the number of sites in the temporal extent. Unlike the results for higher Nt, only one transition of second order was found for Nt = 2 . An extended action with an irrelevant term to suppress Z_2 monopoles enabled us to get a better view of the deconfinement transition as the effects of bulk transition could be suppressed as well. Although the action has no global Z_2 symmetry for the SO(3) theory, unlike the SU(2) theory at finite temperature, our study revealed a second order deconfinement transition, with properties similar to the deconfinement transition of SU(2).

hep-lat↗
arXiv1998

Phase Transitions in SO(3) Lattice Gauge Theory

The phase diagram of SO(3) lattice gauge theory is investigated by Monte Carlo techniques on both symmetric and asymmetric lattices with a view (i) to understanding the relationship between the bulk transition and the deconfinement transition, and (ii) to resolving the current ambiguity about the nature of the high temperature phase. A number of tests, including an introduction of a magnetic field and measurement of different correlation functions in the phases with positive and negative values for the adjoint Polyakov line, lead to the conclusion that the two phases correspond to the same physical state. Studies on lattices of different sizes reveal only one phase transition for this theory on all of them and it appears to have a deconfining nature.

hep-lat↗
arXiv1998

Dimensional Reduction in High Temperature Gauge Theories

Screening masses in the equilibrium thermodynamics of gauge theories were measured. The spectroscopy of these screening masses gives strong evidence for dimensional reduction at $T\ge2T_c$. A perturbative explanation of these masses is ruled out. The mass ratios in the high temperature phase are consistent with those in the pure gauge theory in three dimensions.

hep-ph↗
arXiv1998

Dimensional Reduction and Screening Masses in Pure Gauge Theories at Finite Temperature

We studied screening masses in the equilibrium thermodynamics of SU(2) and SU(3) pure gauge theories on the lattice. At a temperature of 2 Tc we found strong evidence for dimensional reduction in the non-perturbative spectrum of screening masses. Mass ratios in the high temperature SU(3) theory are consistent with those in the pure gauge theory in three dimensions. At the first order SU(3) phase transition we report the first measurement of the true scalar screening mass.

hep-lat↗
arXiv1997

Phase Diagram of SO(3) Lattice Gauge Theory at Finite Temperature

The phase diagram of SO(3) lattice gauge theory at finite temperature is investigated by Monte Carlo techniques with a view i) to understand the relationship between the deconfinement phase transitions in the SU(2) and SO(3) lattice gauge theories and ii) to resolve the current ambiguity of the nature of the high temperature phases of the latter. Phases with positive and negative adjoint Polyakov loop are shown to have the same physics. A first order deconfining phase transition is found for N_t=4.

hep-lat↗
arXiv1996

Stability of the Bulk Phase Diagram of the SU(2) Lattice Gauge Theory with Fundamental - Adjoint Action

Using improved mean field and strong coupling expansions we re-analyse the bulk phase diagram of the fundamental-adjoint action of the SU(2) Lattice Gauge Theory. We find that the qualitative features of the bulk phase diagram are robust and unchanged by the inclusion of higher order terms. On the other hand, some of the quantitative features, such as the location of the endpoint of the line of bulk phase transitions, seem to be strongly dependent on the higher terms of the strong coupling expansion.

hep-lat↗
arXiv1996

Collinear Divergences at One-loop Order for External Particles in a Heat-bath

In hard interactions between external particles incident on a heat-bath, we show that large logarithms are generated when a radiated or absorbed gauge boson is collinear with the initial fermion momentum. These logarithms can be absorbed into process independent splitting/absorption probabilities. Unlike the zero-temperature case, however, they depend explicitly on the temperature and the scale of the interaction.

hep-ph↗