A chiral soliton model of nucleon and delta

From the nonextensive statistical mechanics, we investigate the chiral phase transition at finite temperature and baryon chemical potential in the framework of the linear sigma model. The corresponding nonextensive distribution, based on Tsallis' statistics, is characterized by a dimensionless nonextensive parameter, , and the results in the usual Boltzmann-Gibbs case are recovered when → 1. The thermodynamics of the linear sigma model and its corresponding phase diagram are analysed. At high temperature region, the critical temperature is shown to decrease with increasing from the phase diagram in the ( , ) plane. However, larger values of cause the rise of at low temperature but high chemical potential. Moreover, it is found that different from zero corresponds to a first-order phase transition while = 0 to a crossover one. The critical endpoint (CEP) carries higher chemical potential but lower temperature with increasing due to the nonextensive effects.

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“…Within the linear sigma model, the chiral effective Lagrangian with quark degrees of freedom reads [15,18,19] …”

Section: Theoretical Frameworkmentioning

confidence: 99%

Chiral Phase Transition in Linear Sigma Model with Nonextensive Statistical Mechanics

Shen

Zhang

Hou

et al. 2017

Advances in High Energy Physics

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“…It is a clean-cut problem, and can be solved numerically or, approximately, analytically. The description of baryons based on this construction has been named the Chiral Quark-Soliton Model (CQSM) [113,114,115].…”

Section: Chiral Quark-soliton Modelmentioning

confidence: 99%

Instantons at work

Diakonov

2003

Progress in Particle and Nuclear Physics

347

506

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The aim of this review is to demonstrate that there exists a coherent picture of strong interactions, based on instantons. Starting from the first principles of Quantum Chromodynamics -via the microscopic mechanism of spontaneous chiral symmetry breakingone arrives to a quantitative description of the properties of light hadrons, with no fitting parameters. The discussion of the importance of instanton-induced interactions in soft high-energy scattering is new.

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“…The model parameters for our numerical calculations are taken from Refs. [22,51]: F π = 93MeV , gF π = 500MeV , m π = 139.6MeV , and m σ = 1200MeV .…”

Section: Electric Polarizabilitymentioning

confidence: 99%

“…In recent years numerous hedgehog models, such as the Skyrme model [18][19][20][21], chiral quark models [22][23][24][25][26][27], hybrid bag models [28], chiral models with confinement [26,[29][30][31], or the Nambu-Jona-Lasinio model [32] in the solitonic treatment [33][34][35][36][37][38][39], were quite successful in describing the phenomenology of nucleon structure. The basis for these hedgehogs models is the large-N c limit [40,41] of QCD.…”

Section: Introductionmentioning

confidence: 99%

Response of nucleons to external probes in hedgehog models. I. Electromagnetic polarizabilities

Broniowski

Cohen

1993

Phys. Rev. D

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Electromagnetic polarizabilities of the nucleon are analyzed in a hedgehog model with quark and meson degrees of freedom. Semiclassical methods are used (linear response theory, quantization via cranking). It is found that in hedgehog models (Skyrmion, chiral quark models, Nambu-Jona-Lasinio model), the average electric polarizability of the nucleon, α N , is of the order N c , and the splitting of the neutron and proton electric(proper) polarizabilities, δα = α n − α p , is of the order 1/N c . We present a general argument why one expects δα > 0 in models with a pionic cloud. Our model prediction for the sign and magnitude of δα is in agreement with recent measurements. The obtained value for α N , however, is roughly a factor of three too large. This is because of two problems with our particular model: a too strong pion tail, and the degeneracy of N and ∆ states in the large-N c limit. This degeneracy also results in a very strong N c -dependence of the paramagnetic part of the magnetic polarizability, β, which is of the order N 3 c . We compare the large-N c results to the one-loop chiral perturbation theory predictions, and show the importance of ∆-effects in pionic loops. We also investigate the role of non-minimal substitution terms in the effective lagrangian on the polarizabilities of the nucleon.

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A chiral soliton model of nucleon and delta

Cited by 221 publications

References 7 publications

Chiral Phase Transition in Linear Sigma Model with Nonextensive Statistical Mechanics

Chiral Phase Transition in Linear Sigma Model with Nonextensive Statistical Mechanics

Instantons at work

Response of nucleons to external probes in hedgehog models. I. Electromagnetic polarizabilities

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