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arXiv 1901.10282nucl-th
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从手征夸克-介子理论可以了解热介质中的相变、介子和核子结构吗?

What could be learned about phase transitions, meson and nucleon structure in hot medium from a chiral quark-meson theory?

Christo V. Christov

摘要:

本文总结和讨论了在手征夸克-介子理论框架下得到的热物质的整体热力学特性、介子和核子结构的结果。一个混合NJL模型中使用的狄拉克海的夸克相结合的费米海的夸克或核子。在该模型中,介子被描述为集体$\bar qq$激发,核子表现为与狄拉克海和费米海耦合的$N_c$价夸克的重子一号孤子。根据该模型,在一定的临界密度和/或温度下,可以预期从核子到夸克以及从Goldstone到Wigner相的相变。在有限密度的手征序参量和组分夸克质量有一个非单调的温度依赖性-在温度不接近临界一,他们是受影响比冷物质。夸克物质对热涨落相当软,相应的手征相变是光滑的。核子物质的硬度要大得多,相变非常剧烈。在夸克物质的情况下,一阶跃迁建议在低温($T<80$ MeV)的变化到一个二阶在更高的温度。与夸克物质相反,核子物质的热力学变量显示出大的不连续性,这是一个一阶相变的明确指示。在中温热介质中,核子孤子比在冷物质中束缚得更多,膨胀得更少。当核子物质的临界温度与相变的临界温度相一致时,不再有定域解,根据这个模型,我们可以预期从核子到夸克物质的一级相变。

英文摘要:

In this contribution I summarize and discuss the results of the bulk thermodynamic characteristics, meson and nucleon structure in hot matter obtained in the framework of a chiral quark-meson theory. A hybrid NJL model is used in which a Dirac sea of quarks is combined with a Fermi sea of quarks or of nucleons. In the model mesons are described as collective $\bar qq$ excitations and the nucleon appears as a baryon-number-one soliton of $N_c$ valence quarks coupled to both Dirac and Fermi sea. According to the model at some critical density and/or temperature phase transitions from nucleons to quarks as well as from Goldstone to Wigner phase are expected. At finite density the chiral order parameter and the constituent quark mass have a non-monotonic temperature dependence-at temperatures not close to the critical one they are less affected than in cold matter. The quark matter is rather soft against thermal fluctuations and the corresponding chiral phase transition is smooth. The nucleon matter is much stiffer and the phase transition is very sharp. In the case of quark matter a first-order transition is suggested at low temperatures ($T<80$ MeV) which changes to a second-order one at higher temperatures. In contrast to the quark matter in the case of nucleon matter the thermodynamic variables show large discontinuities which is a clear indication for a first-order phase transition. In hot medium at intermediate temperature the nucleon soliton is more bound and less swelled than in the case of cold matter. At some critical temperature, which for nucleon matter coincides with the critical temperature for the phase transition, no more a localized solution is found. According to this model scenario one should expect a first-order phase transition from nucleon to quark matter.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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