The boundary of the first order chiral phase transition in the m_pi-m_K--plane with a linear sigma model

Tree-level and complete one-loop parametrisation of the linear sigma model (LSM) is performed and the phase boundary between first order and crossover transition regions of the m_pi-m_K-plane is determined using the optimised perturbation theory (OPT) as a resummation tool of perturbative series. Away from the physical point the parameters of the model were determined by making use of chiral perturbation theory (ChPT). The location of the phase boundary for m_pi=m_K and of the tricritical point (TCP) on the m_pi=0 were estimated.Comment: 4 pages, 1 figure, uses espcrc1.sty; to appear in the proceedings of Strong and Electroweak Matter 2006 (SEWM06), BNL, May 200

Sensitivity of the chiral phase transition of QCD to the scalar meson sector

Gribov's theory of light quark confinement implies the existence of two kinds of scalar bound states. The phase diagram of the three-flavor QCD is mapped out in the (m_pi-m_K)-plane with help of the SU_L(3)xSU_R(3) linear sigma model supplemented with the assumption that the masses of the so-called superbound scalars do not change under the variation of the pion and kaon mass. The phase boundary along the m_pi=m_K line is found in the interval 15 MeV<m_crit<25 MeV, irrespective which f_0-sigma linear combination is identified with the pure superbound state.Comment: 11 pages, 3 figures, presented at the Gribov-75 Memorial Workshop on Quarks, Hadrons, and Strong Interactions, Budapest, Hungary, 22-24 May 200

Pion condensation in the two--flavor chiral quark model at finite baryochemical potential

Pion condensation is studied at one--loop level and nonzero baryochemical potential in the framework of two flavor constituent quark model using the one--loop level optimized perturbation theory for the resummation of the perturbative series. A Landau type of analysis is presented for the investigation of the phase boundary between the pion condensed/non-condensed phases. The statement that the condensation starts at \muI = m_{\pi} is slightly modified by one--loop corrections. The second order critical surface is determined and analysed in the \muI-\muB-T space. The \muI dependence of the one--loop level charged pion pole masses is also studied.Comment: 12 pages, 5 figures, submitted to PR

Resummed one-loop determination of the phase boundary of the SU(3)(R) x SU(3)(L) linear sigma model in the (m(pi) - m(K))-plane

Complete one-loop parametrization of the linear sigma model is performed and the phase boundary between first order and crossover transition regions of the m_pi-m_K-plane is determined using the optimized perturbation theory as a resummation tool of perturbative series. Away from the physical point the parameters of the model were determined by making use of chiral perturbation theory. Along the diagonal m_pi=m_K of the mass--plane we estimate m_pi^c=110 +- 20 MeV. The location of the tricritical point on the m_pi=0 axis is estimated in the interval m_K^TCP in (1700,1850) MeV.Comment: RevTeX4, 11 pages, 6 figures, with macro package feynm

Comment on "Finite Size Corrections to the Radiation Reaction Force in Classical Electrodynamics" [arXiv:1005.2617]

In [1, arXiv:1005.2617] effective field theory methods have been employed to compute the equations of motion of a spherically symmetric charged shell of radius R, taking into account the radiation reaction force exerted by the shell's own electromagnetic field up to O(R^2). The authors of Ref. [1] have stated that the known result for the self force of the shell as can be found from Eq. (16.28) of the textbook of Jackson [2] (see also Chap. 4 in the review of Pearle [3]) is incorrect, in that the term linear in R should be absent. We claim that this conclusion of Ref. [1] is incorrect, and that the textbook result, Eq. (1) does hold.Comment: 1 pag

Mapping the boundary of the first order finite temperature restoration of chiral symmetry in the mpi - mK -plane with a linear sigma model

The phase diagram of the three-flavor QCD is mapped out in the low mass corner of the (m(pi)-m(K))-plane with help of the SU(L)(3)xSU(R)(3) linear sigma model (L sigma M). A novel zero temperature parametrization is proposed for the mass dependence of the couplings away from the physical point based on the three-flavor chiral perturbation theory(U(3) ChPT). One-loop thermodynamics is constructed by applying optimized perturbation theory. The unknown dependence of the scalar spectra on the pseudoscalar masses limits the accuracy of the predictions. Results are compared to lattice data and similar investigations with other variants of effective chiral models. The critical value of the pion mass is below 65 MeV for all m(K) value less than or similar to 800 MeV. Along the diagonal m(pi)=m(K), we estimate m(crit)(diag)=40 +/- 20 MeV

High Energy Neutrinos and Photons from Curvature Pions in Magnetars

We discuss the relevance of the curvature radiation of pions in strongly magnetized pulsars or magnetars, and their implications for the production of TeV energy neutrinos detectable by cubic kilometer scale detectors, as well as high energy photons.Comment: 19 pages, 4 figures, to appear in JCA

The order of the quantum chromodynamics transition predicted by the standard model of particle physics

We determine the nature of the QCD transition using lattice calculations for physical quark masses. Susceptibilities are extrapolated to vanishing lattice spacing for three physical volumes, the smallest and largest of which differ by a factor of five. This ensures that a true transition should result in a dramatic increase of the susceptibilities.No such behaviour is observed: our finite-size scaling analysis shows that the finite-temperature QCD transition in the hot early Universe was not a real phase transition, but an analytic crossover (involving a rapid change, as opposed to a jump, as the temperature varied). As such, it will be difficult to find experimental evidence of this transition from astronomical observations.Comment: 7 pages, 4 figure