Skip to content
DraconiticResearch
Search Sources API
178,033 studies31 sourcesUpdated 38 min ago
Peer-reviewedCC BY 4.0The European Physical Journal C

Axion effects on hybrid stars: earlier hadron-quark phase transition and larger quark-matter cores

  • Yu-Heng Liu1
  • He Liu1
  • Hong-Ming Liu1
  • Min Ju2
  • Xu-Hao Wu3
  • Peng-Cheng Chu1
  1. 1Qingdao University of Technology
  2. 2China University of Petroleum (East China)
  3. 3Yanshan University
Open at sourcePDFDOICite

Abstract

We investigate the effects of axions on the properties of hybrid stars and the possible hadron-quark phase transition in their cores within the Maxwell construction. The hadronic phase is described by the improved isospin- and momentum-dependent interaction (ImMDI) model, while the quark phase is modeled by a three-flavor Nambu–Jona-Lasinio (NJL) model with an axion-modified Kobayashi-Maskawa-’t Hooft (KMT) interaction. Based on the obtained equation of state, we analyze the properties of hybrid-star matter, including the speed of sound and the polytropic index, as well as the structural characteristics of hybrid stars, including the mass-radius relation and the properties of the quark core. Our study shows that the axion field a/fa slightly stiffens the equation of state of quark matter but significantly shifts the hadron-quark phase transition to lower baryon densities. These two effects compete in influencing the equation of state of hybrid-star matter, and may even soften it, which is different from the effect of the vector coupling interaction. Consequently, the axion field has only a weak influence on the maximum mass of hybrid stars, but significantly increases the mass and radius of the quark core, especially for weak vector coupling. These results indicate that, within the present Maxwell construction, the primary role of the axion is to promote an earlier hadron-quark transition at low densities and to enlarge the quark core.

Related

  1. Evidence for a Continuous Hadron--Quark Transition in Cold Dense Matter
    Yong-Jia Huang, Bikai Gao
    arXivPreprintCC0Full textHigh-energy astrophysicsHigh-energy & particle physicsarXiv
  2. How Neutron Star Radii Encode the Dense-Matter Equation of State and Hadron-Quark Transition
    Bao-An Li, Xavier Grundler
    arXivPreprintCC0Full textHigh-energy astrophysicsHigh-energy & particle physicsarXiv
  3. How Neutron Star Radii Encode the Dense-matter Equation of State and Hadron–Quark Transition
    Bao-An Li, Xavier Grundler
    The Astrophysical JournalPeer-reviewedCC BY 4.0Full textSolar & stellar physicsIOP/AASCrossref
  4. Astrophysical Constraints on Hadron--Quark Crossover in Hybrid Neutron Stars
    Gábor László Kasza, György Wolf
    arXivPreprintarXiv licenceFull textHigh-energy astrophysicsarXiv
  5. General-purpose equations of state for hadron-quark matter: first application to accretion-induced phase transitions in neutron stars
    János Takátsy, Henrique Gieg, Tim Dietrich
    arXivPreprintCC BY-SA 4.0Full textHigh-energy astrophysicsGravitation & general relativityarXiv

Cite

BibTeXRIS
BibTeX
@article{liu2026axion,
  title = {{Axion effects on hybrid stars: earlier hadron-quark phase transition and larger quark-matter cores}},
  author = {Yu-Heng Liu and He Liu and Hong-Ming Liu and Min Ju and Xu-Hao Wu and Peng-Cheng Chu},
  journal = {The European Physical Journal C},
  year = {2026},
  month = oct,
  doi = {10.1140/epjc/s10052-026-16460-y},
  url = {https://link.springer.com/article/10.1140/epjc/s10052-026-16460-y},
  note = {CC BY 4.0},
}
RIS
TY  - JOUR
TI  - Axion effects on hybrid stars: earlier hadron-quark phase transition and larger quark-matter cores
AU  - Yu-Heng Liu
AU  - He Liu
AU  - Hong-Ming Liu
AU  - Min Ju
AU  - Xu-Hao Wu
AU  - Peng-Cheng Chu
PY  - 2026
DA  - 2026/10/27
JO  - The European Physical Journal C
DO  - 10.1140/epjc/s10052-026-16460-y
UR  - https://link.springer.com/article/10.1140/epjc/s10052-026-16460-y
AB  - We investigate the effects of axions on the properties of hybrid stars and the possible hadron-quark phase transition in their cores within the Maxwell construction. The hadronic phase is described by the improved isospin- and momentum-dependent interaction (ImMDI) model, while the quark phase is modeled by a three-flavor Nambu–Jona-Lasinio (NJL) model with an axion-modified Kobayashi-Maskawa-’t Hooft (KMT) interaction. Based on the obtained equation of state, we analyze the properties of hybrid-star matter, including the speed of sound and the polytropic index, as well as the structural characteristics of hybrid stars, including the mass-radius relation and the properties of the quark core. Our study shows that the axion field a/f_a slightly stiffens the equation of state of quark matter but significantly shifts the hadron-quark phase transition to lower baryon densities. These two effects compete in influencing the equation of state of hybrid-star matter, and may even soften it, which is different from the effect of the vector coupling interaction. Consequently, the axion field has only a weak influence on the maximum mass of hybrid stars, but significantly increases the mass and radius of the quark core, especially for weak vector coupling. These results indicate that, within the present Maxwell construction, the primary role of the axion is to promote an earlier hadron-quark transition at low densities and to enlarge the quark core.
SN  - 1434-6052
SN  - 1434-6044
ER  -