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7 pages, 292 KiB

Open AccessProceeding Paper

New Contribution to the Anomalous π⁰→γγ Decay in SU(2) Chiral Perturbation Theory

by Zhen-Yan Lu, Shu-Peng Wang and Qi Lu

Proceedings 2025, 123(1), 1; https://doi.org/10.3390/proceedings2025123001 - 28 Jul 2025

Viewed by 228

Abstract

The introduction of axions gives rise to additional one-loop diagrams for the two-photon decays of neutral pions via axion-pion mixing. We compute this correction that has been overlooked in existing calculations, within the framework of SU(2) chiral perturbation theory. Our analysis shows that the correction is proportional to the axion-photon coupling and the square of the axion mass. In the classical axion parameter space, this correction is strongly suppressed by the axion decay constant. However, for QCD axions in the MeV or higher mass range, the correction may become significant. Furthermore, when combined with experimental measurements of the decay width of the

π^{0} \to γ γ

process, our results rule out the standard QCD axion as a viable explanation for the observed discrepancy between chiral perturbation theory predictions and experimental data. Full article

(This article belongs to the Proceedings of The 5th International Conference on Symmetry (Symmetry 2025))

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7 pages, 263 KiB

Open AccessProceeding Paper

Recent Progress on Conjecture

O

and Its Variants: A Survey

by Xiaobin Li, Yuhui Peng, Yamin Xu and Bin Zhu

Proceedings 2025, 123(1), 2; https://doi.org/10.3390/proceedings2025123002 - 28 Jul 2025

Viewed by 195

Abstract

Conjecture

O

(and the Gamma Conjectures), introduced by Galkin, Golyshev, and Iritani stand as pivotal open problems in the quantum cohomology of Fano manifolds, bridging algebraic geometry, mathematical physics, and representation theory. These conjectures aim to decode the structural essence of quantum multiplication [...] Read more.

Conjecture

O

O

specifically investigates the spectral simplicity and eigenvalue distribution of the operator associated with the first Chern class

c_{1}

in quantum cohomology rings, positing that its eigenvalues govern the convergence and asymptotic behavior of quantum products. Full article

(This article belongs to the Proceedings of The 5th International Conference on Symmetry (Symmetry 2025))

8 pages, 306 KiB

Open AccessProceeding Paper

Constraints on the Equation of State of Quark Stars from Compact Object Observations

by Shu-Peng Wang, Zhi-Jun Ma, Jian-Feng Xu and Zhen-Yan Lu

Proceedings 2025, 123(1), 3; https://doi.org/10.3390/proceedings2025123003 - 29 Jul 2025

Viewed by 264

Abstract

Introducing an additional term into the thermodynamic potential density of the quark matter system, as required for thermodynamic consistency, resolves the inconsistency that arises in the conventional perturbative quantum chromodynamics (QCD) model. In this work, we use a revised, thermodynamically consistent perturbative QCD [...] Read more.

u d

) quark matter at zero temperature. Our results indicate that the measured tidal deformability for GW170817 places an upper limit on the maximum mass of

u d

quark stars, but does not rule out the possibility of such stars with a mass of about two solar masses. However, when the maximum mass of

u d

quark stars significantly exceeds two solar masses, such as the compact object with a mass in the range of 2.50–2.67

M_{⊙}

observed in the GW190814 event, it cannot be identified as a

u d

quark star according to the revised perturbative QCD model. Full article

(This article belongs to the Proceedings of The 5th International Conference on Symmetry (Symmetry 2025))

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