We investigated the effect of an isospin chemical potential ( $ \mu_{I} $ ) within the quark-meson model, which approximates quantum chromodynamics (QCD) by modeling low-energy phenomena such as chiral symmetry breaking and phase structure under varying conditions of temperature and chemical potential. Using the functional renormalization group (FRG) flow equations, we calculated the phase diagram in the chiral limit within the two-flavor quark-meson model in a finite $ \mu_{I} $ with $\textit{ρ}$ vector meson interactions. Fluctuation effects significantly decrease the critical chemical potential from the mean-field (MF) value $\mu_{I,{\rm MF}} \gt m_\rho$ to a lower value at which the $\textit{ρ}$ vector meson condensates alongside the chiral condensate once the isospin chemical potential exceeds the critical value $ \mu_{I}^{{\rm{crit}}} $ . This $\textit{ρ}$ condensation was investigated numerically for different meson coupling strengths. The $\textit{ρ}$ meson dominated region is delineated from other phases by a second-order phase transition at lower $ \mu_{I} $ and a first-order transition at slightly higher $ \mu_{I} $ .

China

Mohammed Osman

Defu Hou

Wentao Wang

United States

Hui Zhang

Functional renormalization group study of $\textit{ρ}$ meson condensate at a finite isospin chemical potential in the quark meson model * Supported in part by the National Key Research and Development Program of China (2022YFA1604900). This work is also partly supported by the National Natural Science Foundation of China (NSFC) (12435009, 12275104). Hui Zhang acknowledges the financial support from the Guangdong Major Project of Basic and Applied Basic Research (2020B0301030008) and the National Natural Science Foundation of China (12047523, 12105107)

We show that a very clear signal of the presence of a strong magnetic field during the early stage of a high-energy heavy-ion collision is provided by the decay of the <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>Z</mi><mn>0</mn></msup></math> into dimuon pairs. We find that the process is highly anisotropic, producing pairs mainly out of plane, as signaled by a negative value of <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>v</mi><mn>2</mn></msub></math>, and leads to an antimuon transverse momentum distribution which peaks at a higher value of the transverse momentum compared to the peak of the muon transverse momentum distribution. We also show that the process does not produce a significant distortion of the <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>Z</mi><mn>0</mn></msup></math> spectral function. The signal can be identified by comparing the dimuon-invariant mass and the individual muon and antimuon spectra produced in semicentral heavy-ion collisions with the corresponding scaled spectra produced in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>p</mi><mo>+</mo><mi>p</mi></mrow></math> collisions at the <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>Z</mi><mn>0</mn></msup></math> peak.

Mexico

Brazil

Alejandro Ayala

Chile

Ana Julia Mizher

Javier Rendón

Asymmetric muon-antimuon emission from <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>Z</mi><mn>0</mn></msup></math> decays: A potential magnetometer in relativistic heavy-ion collisions

We investigate the formation of primordial black holes (PBHs) induced by a first-order electroweak phase transition in a realistic renormalizable framework, the complex singlet extension of the Standard Model. We perform a quantitative analysis of the PBH abundance and identify parameter regions consistent with current microlensing constraints. Furthermore, we show that the same parameter space predicts observable stochastic gravitational waves within the sensitivities of future space-based detectors, as well as a sizable deviation in the Higgs triple coupling that can be probed at future lepton colliders. Our results highlight a comprehensive multimessenger framework in which PBHs, gravitational waves, and collider observations can jointly test the dynamics of a strongly first-order electroweak phase transition in the early Universe.

Fa Peng Huang

Chikako Idegawa

Aidi Yang

Primordial black hole formation and multimessenger signals in a complex singlet extension of the standard model

We examine the idea that our Universe began as a baby universe and show that this is feasible in a gauged <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi><mo stretchy="false">(</mo><mn>1</mn><msub><mo stretchy="false">)</mo><mrow><mi>B</mi><mo>−</mo><mi>L</mi></mrow></msub></math> extension of the Standard Model with the classically conformal principle. For the first time, we define a measure to describe the probability that we reside in a baby universe, and find that it can be close to 1 in a considerable portion of the parameter space. The framework is consistent with current cosmological data, and it predicts the existence of a heavy neutral gauge boson, which could be detected at colliders, thereby offering a direct link between early universe dynamics and experimentally testable signatures at the TeV scale.

Qing-Hong Cao

Masanori Tanaka

Jun-Chen Wang

Ke-Pan Xie

Jing-Jun Zhang

Can we live in a baby universe formed by a delayed first-order phase transition?

We present a study of the impact of data from the upcoming Electron Ion Collider (EIC) on the determination of the strong coupling within the context of the global MSHT fitting framework. To achieve this, we generate EIC electron-proton scattering pseudodata according to both conservative and optimistic experimental uncertainty projections and perform a simultaneous fit to obtain the proton PDFs and the value of the strong coupling. In the conservative case the impact is found to be moderate, but non-negligible, while in the optimistic case it is observed to be rather significant. These results therefore underline the promising potential for the EIC in the determination of the strong coupling. We in addition explore the impact of any potential tensions between the EIC data and the rest of the data in the global fit by injecting explicit inconsistencies into the pseudodata generation. This can lead to a noticeable bias in the extracted value of the strong coupling, highlighting the importance of accounting for all sources of theoretical uncertainty in the fit as well as the relevance of an enlarged, conservative, error definition in the determination of the strong coupling.

United Kingdom

L. Harland-Lang

Belgium

T. Cridge

P. Newman

R. Thorne

Germany

K. Wichmann

The impact of inclusive electron ion collider data on the strong coupling determination in a global PDF fit

In this work, we explore the new agegraphic dark energy model within the framework of Loop Quantum Cosmology (LQC). A quantum gravitational perspective on the dark energy evolution is explored. A combination of cold dark matter and dark energy in the form of New Agegraphic dark energy is considered with LQC as the background gravity theory. Both the interacting and non-interacting scenarios between dark energy and matter are considered. Various cosmological parameters, like the equation of state parameter, deceleration parameter, and statefinder parameters, are studied. The squared speed of sound is investigated to get an idea about the stability of the system. An observational data analysis using recent cosmological data and the Markov chain Monte Carlo algorithm is performed to constrain the free parameter space of the model. Our findings imply that the interaction of loop quantum effects with agegraphic dark energy offers a nonsingular origin scenario and a theoretically sound and observationally compatible explanation of the universe’s late-time acceleration.

India

Sayani Maity

Aritra Sanyal

Prabir Rudra

New agegraphic dark energy in loop quantum cosmology: a quantum gravitational perspective on dark energy evolution

The interaction problem between solitons and mean flows including the dispersive shock wave, rarefaction wave, kink and contact dispersive shock wave, is discussed in the framework of the Gardner equation, a generic non-convex mathematical model containing quadratic-cubic nonlinear terms, describing the dynamics of internal waves for an arbitrary vertical stratification of the density field. Based on the augmented solitonic modulation system constructed in a Riemann invariant form, two main interaction regimes are identified: soliton tunneling and soliton trapping. Furthermore, kinks and flat-top solitons caused by the non-convexity, play dual roles as both mean flows and localised waves, imparting polarity reversal to solitons and mean flows. Specially, flat-top solitons formed by the quadratic-cubic nonlinear competition, can be considered as a combination of kinks and antikinks, and induce polarity reversal to solitons and mean flows twice, which is an evidence of elastic collisions between flat-top solitons and bell solitons. In addition, the shape of flat-top solitons is changed after the interaction with mean flows. A full classification of the interaction problem is given for both signs of the cubic nonlinear term in the Gardner equation, and numerical simulations agree with modulation theory predictions.

Jia-Xue Niu

Rui Guo

Jian-Wen Zhang

Soliton–mean flow interaction problem for a non-convex system with quadratic-cubic nonlinearity in the stratified fluid

An analysis of baryogenesis and stochastic gravitational wave production is presented for an extension of the Standard Model where the dark sector consists of dark matter particles charged under a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi><mo stretchy="false">(</mo><mn>1</mn><msub><mo stretchy="false">)</mo><mi>x</mi></msub></math> gauge symmetry, while a subset of dark fields also carry lepton number but no <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi><mo stretchy="false">(</mo><mn>1</mn><msub><mo stretchy="false">)</mo><mi>x</mi></msub></math> charge. We demonstrate that, with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> violation induced by Yukawa couplings, equal and opposite lepton asymmetries are generated in the visible and hidden sectors. Subsequent evolution preserves the lepton number separately in each sector, and sphaleron interactions partially convert the lepton asymmetry into baryon asymmetry near the temperature of the first-order phase transition. Furthermore, we discuss stochastic gravitational wave background production for the first-order phase transition using a gauge-independent bubble nucleation dynamics which yields spectra also valid in the supercooled low-temperature regime with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mi>p</mi></msub><mo>/</mo><msub><mi>m</mi><msub><mi>A</mi><mi>x</mi></msub></msub><mo>≪</mo><mn>1</mn></math>, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mi>p</mi></msub></math> is the percolation temperature and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><msub><mi>A</mi><mi>x</mi></msub></msub></math> is the dark photon mass. A parameter-space scan identifies regions that simultaneously account for cogenesis of baryon asymmetry and dark matter and predict stochastic gravitational wave signals within reach of current (NANOGrav, EPTA, and PPTA) and future detectors at higher frequencies, providing a unified framework for cogenesis and associated gravitational wave production.

Wan-Zhe Feng

Jinzheng Li

Pran Nath

Zong-Huan Ye

Gauge-independent gravitational waves from cogenesis in a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo>−</mo><mi>L</mi></math> conserving universe

The gravitational weak lensing of neutrinos in the presence of a Schwarzschild black hole surrounded by a Dehnen-type dark matter halo is investigated. The event horizon structure is explored, and the existence of the BH is studied in two different slices of the parameter space. Additionally, we derive analytic expressions for the oscillation phase and transition probabilities for both radial and non-radial neutrino propagation. Finally, we use a two-flavor toy model, and numerically analyze how the dark matter halo parameters as density and scale radius, affect oscillation probabilities and examine the role of decoherence. The results show that the presence of a dark matter halo modifies the oscillation phase and damping factor, leading to measurable deviations from the standard Schwarzschild BH case. These findings suggest that neutrino oscillations could, in principle, serve as a probe for dark matter distributions around compact astrophysical objects.

Uzbekistan

Mirzabek Alloqulov

Ahmadjon Abdujabbarov

Bobomurat Ahmedov

Chengxun Yuan

Can a Dehnen-type dark matter halo affect the neutrino flavor oscillations?

In this study, we investigate a scenario based on the effects of the Loop Quantum Gravity (LQG) on the electromagnetic sector of the Standard Model of Fundamental Interactions and Particle Physics (SM). Starting from a post-Maxwellian version of electromagnetism that includes LQG effects, we derive and discuss the influence of LQG parameters on classical quantities such as the components of the stress-tensor. Furthermore, we inspect the propagation of electromagnetic waves and examine the optical properties of the QED vacuum in this scenario. Among these, we contemplate the combined effect of the LQG parameters and a homogeneous background magnetic field on the propagation of electromagnetic waves by considering issues such as group velocities and refractive indices of the QED vacuum, in detail. Finally, with the aid of the previously analyzed LQG-extended photonic dispersion relations, we re-discuss the kinematics of the Compton effect and conclude that an interesting nonlinear profile emerges in the wavelengths of the incoming and deflected photons.

P.A.L. Mourão

G.L.L.W. Levy

J.A. Helayël-Neto

Reassessing aspects of LQG-modified dispersion relations of photons * P. A. L. Mourão is support by CAPES. G. L. L. W. L. Levy is support by the Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ), Grant No. E-26/202.437/2024.