Gravitational redshift is a fundamental prediction of general relativity and a sensitive probe of possible deviations from it. Motivated by recent progress in optical clocks and satellite–ground frequency transfer, we study a dual one-way optical Doppler-cancellation observable for space-based gravitational-redshift tests. The corresponding observable is constructed by combining oppositely directed one-way frequency observables, namely, an uplink and a downlink whose measurements are recorded at the receiving terminals and combined in post-processing. We derive the corresponding relativistic observable up to order $$c^{-3}$$ , as required for future $$10^{-18}$$ -level clock comparisons. The resulting combination suppresses the first-order Doppler contribution to second order while retaining the gravitational-redshift signal. We analyze the dominant residual effects, including higher-order Doppler terms, atmospheric delay, Shapiro delay, tidal effects, and clock synchronization. The formalism is applied to representative satellite–ground configurations, including an Atomic Clock Ensemble in Space/China Space Station (ACES/CSS)-like low-Earth-orbit configuration and a geostationary Earth-orbit satellite. The results show that the dual one-way optical DCS configuration provides a useful relativistic framework and error-modeling reference for future $$10^{-18}$$ -level space-based gravitational-redshift tests, while highlighting the need for stringent clock synchronization.

China

Cheng-Gang Qin

Tong Liu

Qin Li

Yang Li

Qi-Long Gong

Zhi-Yu Ma

Yu-Jie Tan

Cheng-Gang Shao

Relativistic formulation for dual one-way Doppler cancellation scheme observables for gravitational redshift tests

We present a phenomenological study of the discovery potential at the FCC-hh for a new heavy neutral vector boson, $$Z^{\prime }$$ , predicted by the $$U(1)_{B-L}$$ gauge symmetry. Focusing on the parameter space currently not excluded by Large Hadron Collider data, we analyze the dilepton production channel $$p p \rightarrow Z^{\prime } \rightarrow l^{+} l^{-}$$ ( $$l^{\pm } = e^{\pm }, \mu ^{\pm }$$ ) at a center-of-mass energy of $$\sqrt{s} = 100$$ TeV. Full Monte Carlo simulations were performed for different ( $$M_{Z'}$$ , $$g_{B-L}$$ ) BSM scenarios and relevant Standard Model backgrounds (including irreducible Drell-Yan, diboson, single top-quark and top-quark pair productions), identifying optimal kinematic selection cuts to guide future searches for this type of resonance. We estimate the FCC-hh reach for an integrated luminosity of $$\mathcal {L}_{int}$$ = 30 $$ab^{-1}$$ . Our results demonstrate that the FCC-hh at full operation can exclude $$Z^{\prime }$$ masses up to $$\sim $$ 50 TeV with 95% C.L. for couplings of $$g_{B-L} \sim 1$$ , and up to $$\sim $$ 30 TeV for $$g_{B-L} \sim 0.1$$ . We find the kinematic cuts that optimize the signal over background ratio and achieve a $$5\sigma $$ signal up to $$Z^{\prime }$$ masses of $$\sim $$ 40 TeV. These findings highlight the FCC-hh potential to uncover new physics signals in the high-mass regime.

Brazil

Chile

Farinaldo Queiroz

J. Zamora-Saa

France

Ricardo Silva

Y. Oviedo-Torres

Can the FCC-hh prove the B-L gauge symmetry?

Using an extended Polyakov-looped Nambu–Jona-Lasinio (PNJL) model to describe the baryon density fluctuations of quark matter along the isentropic trajectories corresponding to different $$s/\rho _B$$ values extracted from Au+Au collisions at energies $$\sqrt{s_{NN}} = 7.7-200$$ GeV, we investigate the effects of the first-order phase transition on the light nucleus yield ratio $$N_t \times N_p/N_d^2$$ . The results indicate that the second-order scaled density moment $$y_2$$ , used to quantify density fluctuations, rapidly increases to form a peak when the isentropic trajectories pass through the phase coexistence region. We extract the yield ratios $$N_t\times N_p/N_d^2$$ at chemical freeze-out from the isentropic trajectories at different collision energies and found significant enhancements at 19.6 GeV and 27 GeV. This is similar to the trends observed by the STAR experiment, suggesting that the enhancements in the yield ratios $$N_t\times N_p/N_d^2$$ observed in the STAR experiment could be explained by the density fluctuations generated in the first-order phase transition region.

He Liu

Kai-Jia Sun

Peng-Cheng Chu

Effects of a first-order QCD phase transition on light nuclei production

Di-muon events emanating from a replica of the SHiP target at the CERN SPS (with a 400 GeV/c proton beam) contain a clear signal of $${J \hspace{-1.66656pt}/\hspace{-1.111pt}\psi \hspace{1.111pt}}$$ production. The target consisted of 13 interaction lengths of molybdenum and tungsten, followed by a 2.4m iron hadron absorber. The di-muon rate is in reasonable agreement with Monte Carlo simulation based on Pythia v8. However, the $${J \hspace{-1.66656pt}/\hspace{-1.111pt}\psi \hspace{1.111pt}} $$ rate observed in the data is much lower than predicted by the Monte Carlo simulation, which is advantageous for SHiP since muons with a large $$p_\textrm{T} $$ are more difficult to deflect by the active muon shield.

Germany

A. Aksoy

Italy

R. Albanese

K. Albrecht

Switzerland

F. Alessio

A. Alexandrov

F. Aloschi

T. Arndt

D. Arutinov

A. Ballarino

L. Baudin

Russia

V. Bautin

A. Bay

I. Bekman

Japan

C. Betancourt

I. Bezshyiko

Ukraine

O. Bezshyyko

D. Bick

United Kingdom

M. Birch

Portugal

A. Castro

Bulgaria

M. Bogomilov

P. Sousa

Netherlands

K. Bondarenko

W. Bonivento

M. Borisyak

N. Bourcey

T. Bowcock

A. Boyarsky

D. Breton

A. Brignoli

L. Brombach

V. Büscher

S. Buontempo

C.S. Caillot

M. Campanelli

D. Centanni

A. Cervelli

S. Charity

South Korea

K. Choi

Georgia

D. Chokheli

A. Chukanov

Belgium

M. Climescu

M. Cristinziani

G. Dallavalle

M. Dam

N. D’Ambrosio

G. D’Appollonio

D. Davino

R. Asmundis

P. Bryas

J. Carvalho Saraiva

G. Lellis

M. Magistris

A. Roeck

M. Serio

G. Giudice

P. Deucher

A. Devred

A. Crescenzo

C. Cristo

H. Dijkstra

D. Dobur

D. Ramos

T. Enik

O. Fecarotta

F. Fedotov

T. Ferber

M. Ferrillo

M. Ferro-Luzzi

A. Fiorillo

H. Fischer

R. Fresa

G. Frisella

S. Garrido

T. Fukuda

G. Galati

E. Gamberini

K. Genovese

B. Goddard

L. Golinka-Bezshyyko

A. Golutvin

Kazakhstan

D. Gorbunov

V. Gorkavenko

E. Graverini

Türkiye

A. Guler

V. Guliaeva

C. Gwilliam

G. Haefeli

C. Hagner

J. Herrera

M. Zeren’e

E. Herwijnen

A. Hollnagel

C. Issever

S. Bermudez

A. Iuliano

R. Jacobsson

Serbia

D. Jokovic

C. Kamiscioglu

V. Kholoimov

S. Kim

Measurement of di-muons from 400 GeV/c protons interacting in a thick molybdenum/tungsten target

This study investigates the nonlinear dynamics of a test particle near the traversable wormhole throat under an external harmonic potential. One-dimensional radial perturbation analysis shows that the particle is locally linearly stable at the equilibrium position. However, for two-dimensional and high-energy cases, the system exhibits a nonlinear response, triggering significant chaotic dynamics.The analysis indicates that, if the particle is confined on one side of the wormhole, the Poincaré section will still retain Kolmogorov–Arnold–Moser (KAM) tori under extremely high-energy conditions, which is distinct from the integrability to chaos transition triggered near the black hole event horizon under external potential.By studying another set of shape functions, the robustness of the observed phase space structure against different geometric profiles is substantiated. This research demonstrates a specific nonlinear dynamical phenomenon of the traversable wormhole. It provides a new criterion, based on chaotic dynamics, for identifying black hole mimickers in strong-field astrophysical observations.

Xin Zhao

Xing-Kun Zhang

Ya-Peng Hu

Yu-Sen An

Chaotic particle dynamics near a traversable wormhole throat

We explore the phenomenological viability of non-minimally coupled Weyl connection gravity by confronting its static, spherically symmetric black hole solutions with classical weak-field Solar System tests and stellar-orbit observations near Sgr A*. In this geometric framework, non-metricity is encoded via a Weyl vector field, giving rise to two distinct families of Schwarzschild-like vacuum solutions characterized by a free parameter $$\omega $$ with dimensions of length. We compute the corrections to four classical observables – gravitational redshift, Mercury’s perihelion advance, light deflection, and radar echo delay – and derive stringent lower bounds on $$\omega $$ using current observational data. For Solution I (purely radial Weyl vector), the leading metric corrections scale as $$1/\omega $$ , yielding bounds as strong as $$\omega > rsim 10^{30}$$ m from perihelion precession. For Solution II (time-radial Weyl vector), the corrections scale as $$1/\omega ^2$$ , resulting in weaker constraints, with $$\omega > rsim 10^{20}$$ m from the same test. This marked difference arises from the distinct behavior of the linear corrections in each solution: while Solution I exhibits an unsuppressed linear term $$2r/\omega $$ that dominates in the Solar System regime, Solution II features a linear term suppressed by an additional factor of $$M/\omega $$ , making the quadratic term $$-r^2/4\omega ^2$$ dominant throughout. We then analyze stellar orbits near the Galactic Center, finding that current observations of the S2 star provide complementary constraints on both solutions. For Solution I, the S2 periastron precession yields $$\omega > rsim 10^{21}$$ m, while the S2 gravitational redshift provides the stronger constraint $$\omega > rsim 10^{24}$$ m. For Solution II, the corresponding bounds are $$\omega > rsim 10^{17}$$ m from periastron precession and $$\omega > rsim 10^{22}$$ m from gravitational redshift. While Solar System tests probe the weak-field regime, these stellar-orbit observations extend the analysis to a substantially stronger gravitational environment. The stellar-orbit analysis reveals a qualitative distinction: Solution I produces a retrograde correction to the periastron precession, while Solution II produces a prograde one, mirroring the behavior identified in the Solar System. Finally, despite both solutions sharing the same quadratic asymptotic structure, only Solution II can accommodate an effective cosmological constant of the same order as the observed value, $$\Lambda _{\textrm{obs}} \sim 10^{-52}$$ m $$^{-2}$$ , while Solution I is constrained to produce a negligibly small effective $$\Lambda $$ .

Iran

Azerbaijan

Mohsen Khodadi

Margarida Lima

Cláudio Gomes

Non-minimally coupled Weyl connection gravity in the Solar System and at the Galactic Center

We construct static, spherically symmetric, and asymptotically flat colored black holes in four-dimensional Einstein gravity coupled to logarithmic nonlinear Yang–Mills theory with gauge group SU(2). Unlike exact solutions based on the Wu–Yang ansatz, these configurations contain a dynamical radial gauge amplitude and arise from a fully coupled boundary-value problem. An integral identity establishes that nontrivial magnetically neutral solutions must be nodal. We obtain the fundamental one-node branch and verify its smooth convergence to the ordinary Einstein–Yang–Mills colored black hole in the weakly nonlinear regime. Increasing the logarithmic nonlinearity lowers the ADM mass, raises the Hawking temperature, and shifts the gauge-field node outward. No termination of the branch is detected within the parameter and radial ranges investigated; instead, the exterior geometry approaches Schwarzschild on fixed radial domains while the colored field develops an increasingly extended tail. A characteristic analysis shows that sufficiently strong logarithmic deformations lose hyperbolicity near the event horizon, restricting their dynamical interpretation. Although the non-Abelian hair carries no independent asymptotic charge, it leaves a subleading gravitational imprint. For representative solutions within the investigated parameter and radial ranges, the numerical interior evolution detects neither an inner Cauchy horizon nor oscillatory mass inflation. Their mass function approaches a finite limit, while the center remains a Schwarzschild-type spacelike curvature singularity. The recovery of the linear theory is nonuniform near the center, where every finite nonlinear deformation eventually enters the strongly logarithmic regime. Temperature turning points also mark changes of local thermodynamic stability, without implying a global phase transition.

Celio Muniz

Colored black holes in logarithmic nonlinear Yang–Mills theory

We study a massive scalar field on the rotating Kalb–Ramond black hole of Kumar et al. [7], near extremality in $$(a,\gamma ,\lambda )$$ . The Klein–Gordon–Fock equation separates, with $$\Lambda _\textrm{rad}=\Lambda _\textrm{ang}+a^{2}\omega ^{2}-2am\omega $$ . At extremality $$\Delta $$ and $\textit{K}$($\textit{r}$) share a zero, keeping $$K^{2}/\Delta $$ regular and reducing the radial problem to Whittaker form on the Kerr line $$\gamma =0$$ and the Kerr–Newman line $$\lambda =1$$ . Stationary resonances saturate $$\omega =m\,\Omega _{H}$$ with $$\mu _\textrm{cloud}>m\,\Omega _{H}$$ , overtones accumulating from above. In the genuine Kalb–Ramond interior $$0<\lambda <1$$ no such reduction exists; we solve the exact radial equation numerically, validated against the closed forms to eleven digits. Off extremality, $$a=a_\textrm{ext}(1-\delta ^{2})$$ , the clouds join the co-rotating zero-damped branch $$\omega _{n}=m\,\Omega _{H}-i\,\kappa \,(n+\tfrac{1}{2}+\beta )$$ , governed by the near-horizon exponent $$\beta $$ and distinct from the photon-sphere family. Greybody factors and superradiance follow from direct integration, recovering the classical $$\ell =m=1$$ Kerr result. Strong-field lensing follows in the Bozza–Tsukamoto limit, the shadow from Carter separation. Intersecting the Event Horizon Telescope window of Zubair et al. [8] with our cloud-existence region bounds $$(\gamma ,\lambda )$$ more tightly than either alone.

Gülnihal Aydemir

İzzet Sakallı

Stationary scalar clouds, quasinormal ringing, and observational signatures of (near-)extremal rotating Kalb–Ramond black holes: from the superradiant threshold to EHT bounds

Allowing for greater low redshift flexibility through parametrizations such as CPL can lead to apparent deviations from $$\Lambda $$ CDM. This motivates an investigation into whether such deviations reflect genuine dynamical dark energy or arise from parametrization choices. We investigate several dark energy parametrizations, including two phenomenological power law type extensions proposed here, the power law and modified power law forms, which allow greater low redshift flexibility (around $$z \sim 1$$ ) than CPL. Parametrizations permitting stronger evolution of the equation of state can exhibit enhanced phantom like behaviour at intermediate redshifts, but this feature is sensitive to the assumed functional form and its extrapolation. The statistical preference for such behaviour is modest, depends on the supernova sample, and is consistent across parametrizations, in agreement with recent analyses. The likelihood-ratio significance of this preference is 2.2– $$3.9\sigma $$ . Owing to limited data at $$z > 2$$ , this is primarily driven by the equation of state in the range $$1 \le z \le 2$$ , where parametrizations with enhanced flexibility, such as power law type forms, mildly improve the fit. The Akaike Information Criterion favours the DDE parametrizations over $$\Lambda $$ CDM for all three supernova samples. The Bayesian Information Criterion mildly favours them for +Union3 and +DESY5 but disfavours them for +PantheonPlus.

India

Md. Hossain

Probing the sensitivity of dark energy dynamics to equation of state parametrization flexibility

Some cumulants of the fluctuations of conserved charges soon above the chiral crossover behave as if the quarks were free. This was taken by many as evidence of deconfinement. At the same temperatures the mesonic correlators reveal the chiral spin and $\textit{SU}$(4) symmetries, indicating that the propagating degrees of freedom are massless quarks connected into color singlets by the chromoelectric confining string. These correlators are qualitatively different from the free quark gas. Here we clarify the reason for the difference. The conserved quark number densities do not propagate in time but do propagate in spatial directions. The mesonic propagators calculated in full QCD differ radically from the free quark loop (quark gas) above $$T_{ch}.$$ In contrast, the quark number density spatial propagator in full QCD at $$T \ge 220$$ MeV is very close to the free quark loop. In other words, the conserved charges do not see confinement, in contrast to the mesonic correlators. This is consistent with the well understood quark-hadron duality at $$T=0$$ in $$e^+e^- \rightarrow hadrons,$$ where at invariant masses above 2 GeV the cross-section in the confining regime is represented by the free quark loop plus small perturbative corrections. All these features above $$T_{ch}$$ but below the deconfinement temperature $$T_d$$ can be combined within the following microscopic picture of the stringy fluid matter. It is a medium of the overlapping strongly interacting color singlet clusters. The quark interchanges between the clusters, required by Pauli principle, make the quarks quasifree, which is reflected in fluctuations of conserved charges.

Austria

L. Glozman

Why fluctuations of conserved charges in the confining regime above $$T_{ch}$$ behave as if the quarks were free?