Interface effects of strange quark matter with density dependent quark masses

Abstract

We study the interface effects in strangelets adopting mean-field approximation (MFA). Based on an equivparticle model, the linear confinement and leading-order perturbative interactions are included with density-dependent quark masses. By increasing the confinement strength, the surface tension and curvature term of strange quark matter (SQM) become larger, while the perturbative interaction does the opposite. For those parameters constrained according to the 2M strange star, the surface tension is ∼2.4 MeV/fm 2 , while unstable SQM indicates a slightly larger surface tension. The obtained results are then compared with those predicted by the multiple reflection expansion (MRE) method. In contrast to the bag model case, it is found that MRE method overestimates the surface tension and underestimates the curvature term. To reproduce our results, the density of states in the MRE approach should be modified by proper damping factors.

Systematic study on the quark-hadron mixed phase in compact stars

“…Note that at μ B ≈ 1400 MeV, for few cases, the perturbation model predicts smaller baryon number density of quark matter than that of hadronic matter, which causes fluctuations if the surface tension is estimated with Σ ¼ 14.3Δn þ 1.3. At larger μ B , the relation 0.3Σ MRE ≈ 14.3Δn þ 1.3 can be fulfilled approximately, which coincides with the predictions of equivparticle model [62,63]. With the surface tension values indicated in Fig.…”

“…The surface tension predicted by the MRE method is then obtained with Σ ¼ Σ MRE ¼ P i¼u;d;s Σ MRE i . Nevertheless, the MRE method tends to overestimate the surface tension by twice the value obtained with equivparticle model [62,63]. This is mainly due to the different confinement potential adopted in those models, where the bag mechanism of the MRE method introduces an infinite wall that results in a sharp density discontinuity.…”

“…At the quark-hadron interface, the wave functions of quarks approach to zero due to the presence of a confinement potential, where quarks are depleted and the corresponding energy contribution can be treated with a surface tension Σ. Based on Massachusetts Institute of Technology (MIT) bag model [107], linear sigma model [108][109][110], NJL model [111,112], three-flavor Polyakovquark-meson model [113], Dyson-Schwinger equation approach [114], equivparticle model [62], nucleon-meson model [115], and Fermi gas approximations [116,117], recent estimations suggest that the surface tension is likely small and Σ ≲ 30 MeV=fm 2 . Nevertheless, larger Σ was also predicted in other investigations [118][119][120].…”

“…Note that the surface tension obtained by the equivparticle model [62,63] was for the quark-vacuum interface. The contributions from the hadron phase can be roughly included by replacing the density of quark matter n Q by the density difference Δn ≡ jn Q − n H j between the two phases.…”

Constraining quark-hadron interface tension in the multimessenger era

“…It is found that σ c (in MeV/fm 2 ) increases linearly with µ T (in MeV) and can be well approximated with σ c = 0.23(µ T − 930) + 19, where the coefficients depend on the EoSs of HM and QM. In such cases, if the deconfinement phase transition occurs at large µ T , the emergence of geometrical structures may be inevitable in hybrid stars since typical estimations suggest σ < σ c with σ < ∼ 30 MeV/fm 2 [77][78][79][80][81][82][83][84]86].…”