activity
20242026
collaborators

6 papers

hep-ph2026

The canonical approach at high temperature revisited

Kouji Kashiwa, Hiroaki Kouno

This paper discusses a paradox encountered when employing the canonical approach, particularly in the high-temperature region where the Roberge-Weiss transition exists at finite im…

hep-ph2026

Effective degrees of freedom, trace anomaly and c-theorem like condition in the hadron resonance gas model

Hiroaki Kouno, Riki Oshima, Kouji Kashiwa

The relation between the effective degrees of freedom (EDOF) and the trace anomaly is studied in the hadron resonance gas (HRG) model. If we regard the thermodynamical relation as…

hep-ph2026

Thermodynamic geometry in hadron resonance gas model at real and imaginary baryon chemical potential and a simple sufficient condition for quark deconfinement

Riki Oshima, Hiroaki Kouno, Motoi Tachibana +1

The thermodynamic geometry of the hadron resonance gas model with (without) excluded volume effects (EVE) of baryons is investigated. The case with imaginary mu, where mu is the ba…

hep-ph2025

Polyakov-loop phase, Roberge-Weiss periodicity and thermodynamics

Kouji Kashiwa, Hiroaki Kouno

In this paper, we discuss the role of Roberge-Weiss periodicity in the thermodynamics of quantum chromodynamics at moderately high temperature, where the semi-quark-gluon plasma is…

hep-ph2024

Hadron-quark hybrid model, modular transformation and Roberge-Weiss transition

Hiroaki Kouno, Riki Oshima, Motoi Tachibana +1

In the framework of modular transformations, we reformulate the recently proposed hadron-quark hybrid model when the imaginary baryonic chemical potential is introduced. As a resul…

hep-ph2024

Roberge-Weiss periodicity and singularity in hadron resonance gas model with excluded volume effects

Riki Oshima, Hiroaki Kouno, Kouji Kashiwa

Quantum chromodynamics (QCD) with pure imaginary baryon number chemical potential mu =i theta T, where T is temperature and theta is a real number, has the Roberge-Weiss periodicit…