Scalar σ meson at a finite temperature in a nonlocal quark model

Abstract

Properties and temperature behavior of π and σ bound states are studied in the framework of the nonlocal model with a separable interaction kernel based on the quark Dyson-Schwinger and the meson Bethe-Salpeter equations. M π (T ), f π (T ), M σ (T ) and Γ σ→ππ (T ) are considered above and below the deconfinement and chiral restoration transitions.

ηandη′mesons in the Dyson-Schwinger approach at finite temperature

“…Its behavior precisely shows the value of the chiral symmetry restoration temperature T Ch , because f 0 π (T ) vanishes at T = T Ch , as does the chiral condensate qq(T ) 0 . We also confirm [33] the result of earlier DS studies at finite and Mss(T ), are depicted by the long-dashed, short dashed and dash-dotted curves, respectively. They practically do not change with temperature till T ≈ 0.95 T Ch , after which they rise monotonically towards the thin diagonal line, which (in all figures displaying masses) represents twice the zeroth Matsubara frequency, 2πT .…”

“…[33,34,35], where fitting the properties of non-strange (N S) mesons, containing just u-and d-quarks, fixed the parameters to…”

“…[32,33,34,35], the Matsubara formalism is used for calculations at T > 0. The usage of the above separable model interaction simplifies greatly DS equations and calculations at finite T , while yielding equivalent results on a given level of truncation [32,36], and a similar quality of results for pions [32,33] and now also for kaons [34] (and fictitious ss pseudoscalars) at T = 0 as in Refs. [28,29,30,31], which employ more realistic interactions while modeling QCD.…”

η′ and η mesons at high T when the Horvatić1, Kekez2, Klabučar3 2019Phys. Rev. D249800View full textAdd to dashboardCite

“…Such models-socalled rank-2 separable models-are phenomenologically successful (see, e.g., Refs. [23][24][25][26][27]). However, they have the well-known drawback of predicting a somewhat too low transition temperature: the model we use in this paper and that was used in Refs.…”

Pions in the quark matter phase diagram

“…The CBM experiment planned at FAIR Darmstadt and the NICA project at JINR Dubna could be capable of creating thermodynamical conditions for the observation of these excitations in the experiment. One promising signal could be the scalar resonance in the pionpion scattering at the two-pion threshold which is in principle observable, e.g., in the two-photon decay channel [39,40]. However, the description of this state goes beyond the Gaussian approximation to which we restrict ourselves in this work.…”