We perform a comparative phase space analysis of the light mass Galileon model and standard quintessence in the context of late-time cosmic acceleration. Focusing on a spatially flat FLRW background, we consider a cubic Galileon interaction supplemented by a scalar potential and examine three representative choices of the potential: a generalized cosh potential, a simple cosh potential, and a linear potential. By introducing suitable dimensionless variables, the cosmological field equations are reformulated as an autonomous dynamical system, allowing a systematic investigation of the stationary points and their stability properties. For the light mass Galileon scenario, we find that although the phase space admits scalar field dominated solutions, all critical points are of saddle type for the potentials considered. In particular, no stable late-time accelerating attractor emerges, even in the presence of de-Sitter like configurations. In contrast, the quintessence limit admits stable de-Sitter attractors for cosh potentials, providing a viable description of the observed late-time acceleration. Our results highlight a key qualitative distinction between Galileon and quintessence cosmologies and indicate that, within the light mass Galileon framework, the higher-order Galileon interactions may be required to realize a stable accelerating Universe.

Kazakhstan

India

Mohd Shahalam

Galileon versus quintessence: a comparative phase space analysis and late-time cosmic relevance

$\textit{U}$-spin symmetry, which reflects the symmetry between the down-type $\textit{d}$ and $\textit{s}$ quarks, is a powerful tool for analyzing heavy hadron weak decays. Motivated by recent experimental achievements in the bottom baryon sector, we study the $\textit{U}$-spin sum rules for bottom baryon decays. The effective Hamiltonian for $\textit{b}$ quark decay is zero under the $\textit{U}$-spin lowering operators $$U_-^n$$ , permitting us to derive $\textit{U}$-spin sum rules involving only the $$b\rightarrow d$$ transition or $$b\rightarrow s$$ transition. Moreover, a new operator, $$S_b=U_++rU_3-r^2U_-$$ , is proposed to generate $\textit{U}$-spin sum rules involving both the $$b\rightarrow d$$ and $$b\rightarrow s$$ transitions. The proof that the effective Hamiltonian for $\textit{b}$ quark decay is zero under $$U_-^n$$ and $$S_b$$ is presented. The master formulas for generating $\textit{U}$-spin sum rules for the two-body decays of bottom baryons involving $$b\rightarrow c\overline{c}d/s$$ , $$b\rightarrow c\overline{u}d/s$$ , $$b\rightarrow u\overline{u}d/s$$ , and $$b\rightarrow u\overline{c}d/s$$ transitions are derived. Numerous $\textit{U}$-spin sum rules for the two-body decays of bottom baryons are obtained through these master formulas, which provide hints for new decay modes and enable the extraction of dynamical information. As a phenomenological analysis, some branching fractions are predicted according to $\textit{U}$-spin symmetry. Several rate and decay parameter sum rules beyond the $\textit{U}$-spin limit are found, providing a more precise test of flavor symmetry in the bottom baryon sector. Moreover, some $\textit{CP}$ asymmetry relations for $\textit{U}$-spin conjugate pairs in heavy baryon decays are derived for the first time by taking partial-wave amplitudes into account.

China

Si-Jia Wen

Wei-Chen Fu

Di Wang

$\textit{U}$-spin sum rules for two-body decays of bottom baryons

Several proposed future lepton colliders are capable of producing trillions of Z-bosons, including FCC-ee, CEPC, LEP3 and LEP-Z. Such Tera-Z factories can discover new elementary particles with couplings to the Z-boson that are orders of magnitude smaller than current bounds. For couplings near the currently excluded parameter regions they could produce sufficiently large samples to study the new particles’ properties in detail, thereby serving as both a discovery and precision machine in one. Using simple analytic estimates, we quantify the dependence of the expected event yield in long-lived particle searches on the number of produced Z-bosons and on the detector dimensions. From this, we derive estimates for both the discovery reach and the measurement precision attainable at such facilities. While the precision of such estimates of course falls short of proper simulations, the analytic approach is suitable for a quick assessment of the sensitivity for a given design. We illustrate this with two examples, heavy neutral leptons and axion-like particles. Under optimistic assumptions, these could be produced in the millions and billions, respectively, effectively turning future lepton colliders into exotics factories.

Belgium

Germany

Marco Drewes

Croatia

Juraj Klarić

Yuan-Zhen Li

New particles at the Z-pole:

We construct a canonical quantization, the Wheeler–DeWitt equation, of the interior geometry of static and spherically symmetric black holes in Einstein–Maxwell- $$\Lambda $$ framework, focusing on Reissner–Nordström. The wave function of the Wheeler–DeWitt equation for the Reissner–Nordström black hole is set to be on-shell and exhibiting exponential damping away from the classical locus. Horizon boundary conditions for the wave function generate two regimes: a single inward mode from event horizon yields monotonic decay, while superpositions produce either a quantum bounce (single time arrow) or interference-driven “annihilation-to-nothing” (two time arrows). We show that these are generic features of static black hole interiors. Furthermore, the wave function of the Schwarzschild black hole, obtained as the charge-neutral limit of the Reissner–Nordström black hole, is monotonically decaying and no longer unbounded. Moreover, this framework unifies classical and quantum interiors, suggests a quantum gravitational suppression to the mass inflation, and motivates extensions to Kerr and regular black holes.

Czechia

Chen-Hsu Chien

South Korea

Woosung Song

Gansukh Tumurtushaa

Taiwan

Canada

Dong-han Yeom

Quantum suppression of mass inflation in Reissner–Nordström interiors via Wheeler–DeWitt equation

In this paper, we present a detailed study of axial gravitational perturbations of the regular black hole solution in asymptotically safe gravity, as proposed in Bonanno et al. (Phys Rev Lett 132:031401, , [gr-qc], 2024). We analyze the quasinormal mode (QNM) spectrum of this black hole using two numerical techniques: the Bernstein spectral method and the asymptotic iteration method (AIM). These approaches allow us to compute QNM frequencies with high accuracy, even for higher overtones. Our results show that the fundamental mode is only weakly affected by the deviation parameter, whereas notable deviations from the Schwarzschild case emerge for higher overtones. Additionally, we examine the correspondence between grey-body factors and QNMs by comparing the WKB grey-body factors with accurate QNM frequencies, finding excellent agreement, especially for larger multipole numbers $$\ell $$ .

Qi-Long Shi

Rui Wang

Wei Xiong

Peng-Cheng Li

Quasinormal modes and grey-body factors of axial gravitational perturbations of regular black holes in asymptotically safe gravity

Hexaquarks, as exotic hadronic states composed of six quarks, represent a fascinating frontier in quantum chromodynamics (QCD). While not yet conclusively observed experimentally, these particles provide crucial insights into the structure of multi-quark systems and serve as important testing grounds for theoretical models. In this work, we investigate the ground-state masses and binding energies of hexaquark configurations formed by the binding of two baryons. We employ the Bethe–Salpeter equation (Salpeter and Bethe in Phys Rev 84:1232, 1951) framework with a phenomenological potential that incorporates color-Coulomb, linear confining, and spin-spin interaction terms. The resulting equation is solved using the Ansatz (Tazimi and Ghasempour in Adv High Energy Phys 2020:2541837, 2020) to obtain precise energy eigenvalues. Our calculations yield mass predictions for various hexaquark systems, including $$\Lambda _c\Lambda _c$$ , $$\Lambda _b\Lambda _b$$ , $$\Sigma _c\Sigma _c$$ , $$\Sigma _b\Sigma _b$$ , $$\Sigma _c^{}\Sigma _c^{}$$ , and $$\Sigma _b^{}\Sigma _b^{}$$ , which show good agreement with existing theoretical studies. Furthermore, we construct Regge trajectories for these hexaquark states, revealing linear behavior in both $$(J,M^2)$$ and $$(n_r,M^2)$$ planes that aligns with established patterns in conventional hadronic spectroscopy. The calculated binding energies indicate the stability of these configurations, supporting their possible existence as resonant states. This comprehensive analysis demonstrates the efficacy of our approach in describing exotic multi-quark systems and contributes to the ongoing search for hexaquarks in experimental facilities.

Iran

M. Ghaderi

N. Tazimi

M. Monemzadeh

Hexaquark bound states and Regge trajectories in QCD via Bethe–Salpeter formalism

The presence of a quintessence-like field can influence the black hole shadow through three primary mechanisms: the dynamics of accretion flows, the trajectories of photons, and the motion of observers. Unlike standard shadow analyses that assume a static observer at spatial infinity, the non-asymptotically flat nature of quintessence-corrected spacetimes motivates the consideration of freely falling (geodesic) observers. Using a perturbative approach, we derive analytical expressions for the event-horizon location, photon-sphere radius, innermost stable circular orbit, and critical impact parameter. We compute the observed intensity profiles for both static and infalling spherical accretion flows. We find that, although the photon-sphere radius and the critical impact parameter are invariant properties of the spacetime, the apparent angular size of the shadow depends sensitively on the observer’s motion and location. Freely infalling observers systematically measure smaller angular radii than static observers at the same radius, whereas freely outgoing observers measure larger ones, in agreement with relativistic aberration. In contrast to the Schwarzschild case, the impact parameter alone is insufficient to characterize the observed angular structure in non-asymptotically flat spacetimes. Applying our results to the Event Horizon Telescope observation of M87 $$^*$$ , we show that more negative equations of state lead to stronger constraints on the quintessence parameter, largely independent of the observer prescription. Our analysis highlights the importance of carefully specifying the observer in shadow studies of non-asymptotically flat black-hole spacetimes.

Ji-Wen Li

Zi-Liang Wang

Tao-Tao Sui

Shadows of quintessence black holes: spherical accretion, photon trajectories, and geodesic observers

In the era of precision measurements in high-energy heavy-ion physics, there is an increasing expectation towards phenomenological and theoretical studies to provide a better description of data. In recent years, multiple experiments have confirmed through two-pion Bose–Einstein correlation measurements that the shape of the two-pion pair source can be well described by Lévy-stable distributions. However, direct comparisons of new phenomenological results with the data are still needed to understand the underlying phenomena and learn more about the nature of pion emission. In this paper, we present a three-dimensional analysis of the two-pion source in Monte-Carlo simulations of $$\text {Au}{+}\text {Au}$$ collisions at 200 GeV per nucleon collision energy based on EPOS3, and discuss a detailed comparison with the most recent centrality-dependent measurements from the PHENIX Collaboration. We find that the model remarkably agrees with the data for peripheral collisions, while an increasing discrepancy is found in case of central collisions for the source shapes and sizes. On the other hand, scaled correlation strengths are found to be well described by the model across all investigated system sizes.

Hungary

Dániel Kincses

Emese Árpási

László Kovács

Márton Nagy

Máté Csanád

Three-dimensional sizes and shapes of pion emission in heavy-ion collisions

Nanohertz gravitational waves (GWs) from supermassive binary black holes (SMBBHs), detectable via pulsar timing arrays (PTAs), offer a novel avenue to constrain dark energy. Based on cosmological simulations and semi-analytic galaxy formation models, this study explores the detectability of individual nanohertz SMBBH sources using next-generation PTAs and their potential for constraining dark energy under an optimistic scenario considering only the presence of white noise. By constructing light-cone SMBBH populations across hardening timescales $$(\tau _H = 0.1/5/10$$ Gyr) and computing signal-to-noise ratios (SNR), we find advanced PTAs can resolve $$10^2$$ – $$10^3$$ sources with SNR $$> 8$$ (primarily at $$z < 1$$ with chirp masses of $$10^8$$ – $$10^{10}M_{\odot }).$$ If electromagnetic counterparts can be identified, optimal configurations $$(\sigma _t = 50$$ ns, $$N_p = 1000,$$ $$T_{\text {obs}} = 30$$ yr with $$ \tau _H \le 5$$ Gyr) could constrain the dark energy equation-of-state (EoS) parameter $\textit{w}$ to $$\Delta w \sim 0.023$$ –0.048, where the constraints only exhibit weak dependence on $$\tau _H$$ within 0.1–5 Gyr. If only $$10\%$$ of GW sources have detectable electromagnetic counterparts, constraints weaken to $$\Delta w = 0.075$$ $$(\tau _H = 0.1$$ Gyr) and $$\Delta w = 0.162$$ $$(\tau _H = 5$$ Gyr) under the most optimal parameter configuration. What’s more, conservative PTAs $$(N_p = 500,$$ $$\sigma _t = 100$$ –200 ns) with additional 30-year data accumulation could double resolvable source counts and improve $$\Delta w$$ precision by $$\sim 40\%.$$

Qing Yang

Gu-yue Zhang

Yi Huang

Xiao Guo

Prospective constraints on dark energy from nanohertz individual gravitational wave sources

Constraints on Wilson coefficients (WCs) corresponding to dimension-6 operators of the standard model effective field theory (SMEFT) are determined from a simultaneous fit to seven sets of CMS measurements probing Higgs boson, electroweak vector boson, top quark, and multijet production. Measurements of electroweak precision observables are also included and provide complementary constraints to those from the CMS experiment. The CMS measurements, using LHC proton-proton collision data at $$\sqrt{s}=13\,\text {Te}\text {V} $$ , corresponding to integrated luminosities of 36.3 or 138 $$\,\text {fb}^{-1}$$ , are chosen to provide sensitivity to a broad set of operators, for which consistent SMEFT predictions can be derived. These are primarily measurements of differential cross sections which are parameterized as functions of the WCs. In measurements targeting $${\text {t}} (\bar{\textrm{t}})\text {X} $$ production, SMEFT effects are modelled at the detector level. Individual constraints on 64 WCs, and constraints on 43 linear combinations of WCs, are obtained.

Armenia

V. Chekhovsky

A. Hayrapetyan

V. Makarenko

A. Tumasyan

Austria

W. Adam

J. Andrejkovic

L. Benato

T. Bergauer

K. Damanakis

M. Dragicevic

C. Giordano

P. Hussain

M. Jeitler

N. Krammer

A. Li

D. Liko

I. Mikulec

J. Schieck

R. Schöfbeck

D. Schwarz

M. Sonawane

W. Waltenberger

C.E. Wulz

T. Janssen

H. Kwon

T. Laer

P. Mechelen

J. Bierkens

N. Breugelmans

J. D’Hondt

S. Dansana

A. Moor

M. Delcourt

F. Heyen

Y. Hong

S. Lowette

I. Makarenko

D. Müller

S. Tavernier

M. Tytgat

G. Onsem

S. Putte

D. Vannerom

B. Bilin

B. Clerbaux

A. Das

I. Bruyn

G. Lentdecker

H. Evard

L. Favart

P. Gianneios

A. Khalilzadeh

F. Khan

A. Malara

M. Shahzad

L. Thomas

M. Vanden Bemden

C. Vander Velde

P. Vanlaer

F. Zhang

M. Coen

D. Dobur

G. Gokbulut

J. Knolle

L. Lambrecht

D. Marckx

K. Skovpen

N. Bossche

J. Linden

J. Vandenbroeck

L. Wezenbeek

S. Bein

A. Benecke

A. Bethani

G. Bruno

A. Cappati

J. Favereau De Jeneret

C. Delaere

A. Giammanco

A. Guzel

Sa. Jain

V. Lemaitre

J. Lidrych

P. Mastrapasqua

S. Turkcapar

Brazil

G. Alves

E. Coelho

G. Correia Silva

C. Hensel

T. Menezes De Oliveira

C. Mora Herrera

P. Rebello Teles

M. Soeiro

E. Tonelli Manganote

A. Vilela Pereira

W. Aldá Júnior

M. Barroso Ferreira Filho

H. Brandao Malbouisson

W. Carvalho

J. Chinellato

Combined effective field theory interpretation of Higgs boson, electroweak vector boson, top quark, and multijet measurements