22,064 research outputs found

    Vacuum structure and effective potential at finite temperature: a variational approach

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    We compute the effective potential for ϕ4\phi^4 theory with a squeezed coherent state type of construct for the ground state. The method essentially consists in optimising the basis at zero and finite temperatures. The gap equation becomes identical to resumming the infinite series of daisy and super daisy graphs while the effective potential includes multiloop effects and agrees with that obtained through composite operator formalism at finite temperature.Comment: 15 pages, Revtex, No figures, to appear in Jou. of Phys.G(Nucl. and Part. Phys.

    Strong CP violation and chiral symmetry breaking in hot and dense quark matter

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    We investigate chiral symmetry breaking and strong CP violation effects in the phase diagram of strongly interacting matter. We demonstrate the effect of strong CP violating terms on the phase structure at finite temperature and densities in a 3-flavor Nambu-Jona-Lasinio (NJL) model including the Kobayashi-Maskawa-t'Hooft (KMT) determinant term. This is investigated using an explicit structure for the ground state in terms of quark-antiquark condensates for both in the scalar and the pseudoscalar channels. CP restoring transition with temperature at zero baryon density is found to be a second order transition at θ=π\theta = \pi while the same at finite chemical potential and small temperature turns out to be a first order transition. Within the model, the tri-critical point turns out to be (Tc,μc)(273,94)(T_c,\mu_c)\simeq(273,94) MeV at θ=π\theta = \pi for such a transition.Comment: 10 pages, 12 figure

    Interior gap superfluidity in a two-component Fermi gas of atoms

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    A new superfluid phase in Fermi matter, termed as "interior gap" (IG) or "breached pair", has been recently predicted by Liu and Wilczek [Phys.Rev.Lett. {\bf 90}, 047002 (2003)]. This results from pairing between fermions of two species having essentially different Fermi surfaces. Using a nonperturbative variational approach, we analyze the features, such as energy gap, momentum distributions, and elementary excitations associated with the predicted phase. We discuss possible realization of this phase in two-component Fermi gases in an optical trap.Comment: 5 page
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