We investigate the motion of neutral test particles around a non-rotating regular black hole within the framework of asymptotically safe gravity, analyzing the impact of the black hole’s parameters on particle motion. This black hole solution is characterized by an additional parameter, $$\eta $$ , which differentiates it from the standard Schwarzschild black hole solution. We obtain analytical formulations for the energy and angular momentum of equatorial circular orbits as functions of the black hole parameter. The stability of these circular orbits is examined by the effective potential. Additionally, we present a graphical study of the innermost stable equatorial circular orbits as functions of the black hole parameter and investigate the effective force exerted on circular orbits. We also derive the frequencies of radial and latitudinal harmonic oscillations as functions of the model parameters and discuss the key features of quasi-periodic oscillations of test particles near stable circular orbits in the black hole’s equatorial plane. The phenomenon of periastron precession is also considered. Additionally, we explore particle collisions near the black hole and demonstrate that such collisions can produce high energy near the event horizon. Our findings indicate that the black hole parameter significantly influences the motion of test particles around a regular black hole in the context of asymptotically safe gravity. We examine the shadow of black hole and using observational data from the Event Horizon Telescope (EHT) collaboration for Sgr A* and M87*, we have determined the range of $$\eta $$ parameter that corresponds to the observations.

China

Azerbaijan

G. Mustafa

Uzbekistan

Asalkhon Alimova

Farruh Atamurotov

Saudi Arabia

Awad Ibraheem

Thailand

Phongpichit Channuie

Gunel Bahaddinova

Testing regular black holes in the framework of asymptotically safe gravity using particle dynamics, QPOs, and shadow constraints

The magnetic moment of the muon can receive significant two-loop contributions from a light pseudoscalar. Notably, the spectrum of scalars of 3-3-1 models includes one pseudoscalar. However, this scalar spectrum inevitably gives rise to flavor-changing neutral current (FCNC) processes. In this study, we examine, within the 3-3-1 model with right-handed neutrinos, whether such spectrum of scalars can account for the anomalous magnetic moment of the muon, considering the constraints imposed by $\textit{B}$-meson decays, meson mixing, and invisible Higgs decays. Our principal finding reveals that a pseudoscalar with mass around 66 GeV and $$\tan \beta =58$$ can account for the $$g-2$$ anomaly without conflicting with flavor physics.

Brazil

A. Doff

Spain

João Pinheiro

C. S. Pires

Exploring solutions to the muon g-2 anomaly in a 3-3-1 model under flavor constraints

This study investigates the existence and stability of traversable wormhole (WH) solutions within the framework of Rastall Teleparallel Gravity. In this context, we focus on the impact of geometric constraints and energy conditions. Utilizing the class I embedding technique under the Karmarkar condition, we derive two novel static spherically symmetric WH solutions. In addition, these solutions are illustrated with distinct redshift functions, leading to corresponding shape functions that satisfy the Morris-Thorne criteria, ensuring asymptotic flatness and necessary throat conditions. The field equations, constructed within an anisotropic stress-energy tensor framework, are analyzed to evaluate the energy density, radial pressure, and tangential pressure distributions. A comprehensive graphical analysis tested the energy conditions, i.e., the null energy condition (NEC), weak energy condition (WEC), strong energy condition (SEC), and dominant energy condition (DEC). This shows the violations of the Null Energy Condition (NEC), confirming the presence of exotic matter necessary for sustaining WH structures. Both models exhibit regions where the energy density remains positive, while radial and tangential pressures violate classical energy conditions, reinforcing the theoretical expectations for the stability of the WH. Also, these results illustrated the compatibility of Rastall Teleparallel Gravity with traversable WH subjects and tested the intricate matter-geometry interplay in exotic spacetimes.

Pakistan

Amna Saleem

Zulfiqar Ali

Algeria

Abdelmalek Bouzenada

Allah Ditta

New relativistic traversable wormholes and energy constraints in the rastall teleparallel gravitational paradigm

We study the most general $\textit{G}$ -invariant AdS vacua in 11 dimensional supergravity preserving 4 real supercharges, with the goal of understanding the IR fixed points of the RG flow induced by the cubic deformation of the ABJM theory. We identify a new $\textit{G}$ -invariant background, which completes the web of RG flows connecting its holographic dual with the ABJM theory and the (cubic analogue of) mass-deformed ABJM theory with SU(3) × U(1) isometry. Our holographic study gives non-trivial predictions for the strongly-coupled field theory dual.

Belgium

Xuao Zhang

New $\textit{G}$

Despite the prominence of tensor mesons in photon-photon collisions, until recently their contribution to the hadronic light-by-light (HLbL) scattering part of the anomalous magnetic moment of the muon has been estimated to be at the level of only a few 10 , with an almost negligible contribution to the error budget of the Standard Model prediction. A recent reanalysis within the dispersive approach has found that after resolving the issue of kinematic singularities in previous approaches, a larger result is obtained, a few 10 , and with opposite sign as in previous results, when a simple quark model for the transition form factors is employed. In this paper, we present the first complete evaluation of tensor meson contributions within a hard-wall model in holographic QCD, which reproduces surprisingly well mass, two-photon width, and the observed singly virtual transition form factors of the dominant $\textit{f}$ (1270), requiring only that the energy-momentum tensor correlator is matched to the leading OPE result of QCD. Due to a second structure function that is absent in the quark model and in lowest-order resonance chiral theory, the result for $\textit{a}$ turns out to be positive instead of negative, and also with a magnitude of a few 10 . We discuss both pole and non-pole contributions arising from tensor meson exchanges in the holographic HLbL amplitude, finding that keeping all contributions improves dramatically the convergence of a sum over excited tensor mesons and avoids unnaturally large contributions from the first few excited modes at low energies. Moreover, we find that the infinite tower of tensor mesons permits to fill the gap in the symmetric longitudinal short-distance constraint on the HLbL amplitude left by the contribution of axial vector mesons. Matching the corresponding leading-order OPE result leads to two-photon couplings consistent with the observed combined effects of the ground-state $\textit{f}$ $\textit{, a}$ $\textit{,}$ $$ {f}_2^{\prime } $$ multiplet and a total $$ {a}_{\mu}^{\textrm{Tensor}} $$ contribution of +12$\textit{.}$4 × 10 ; with an $\textit{F}$ fit this is reduced slightly to +11$\textit{.}$1 × 10 . A contribution of this size from the tensor sector could explain the tension between the most recent dispersive and lattice results for $$ {a}_{\mu}^{\textrm{HLbL}} $$ .

Italy

Luigi Cappiello

Austria

Josef Leutgeb

Jonas Mager

Anton Rebhan

Tensor meson transition form factors in holographic QCD and the muon $\textit{g −}$ 2

We present results for the dominant light-quark connected contribution to the long-distance window of the hadronic vacuum polarization (HVP) contribution to the muon <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>g</mi><mo>−</mo><mn>2</mn></math> from lattice quantum chromodynamics. Specifically, with a new determination of the lattice scale on MILC’s physical-mass HISQ ensembles, using the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi mathvariant="normal">Ω</mi><mo>−</mo></msup></math> baryon mass, we obtain a result of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mi>a</mi></mrow><mrow><mi>μ</mi></mrow><mrow><mi>l</mi><mi>l</mi><mo>,</mo><mi>LD</mi></mrow></msubsup><mo stretchy="false">(</mo><mrow><mi>conn</mi></mrow><mo stretchy="false">)</mo><mo>=</mo><mn>400.2</mn><mo stretchy="false">(</mo><mn>2.3</mn><msub><mrow><mo stretchy="false">)</mo></mrow><mrow><mi>stat</mi></mrow></msub><mo stretchy="false">(</mo><mn>3.7</mn><msub><mrow><mo stretchy="false">)</mo></mrow><mrow><mi>syst</mi></mrow></msub><mo stretchy="false">[</mo><mn>4.3</mn><msub><mrow><mo stretchy="false">]</mo></mrow><mrow><mtext>total</mtext></mrow></msub><mo>×</mo><mspace linebreak="goodbreak"></mspace><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>10</mn></mrow></msup></mrow></math>. Summing this result with our recent determinations of the light-quark connected contributions to the short- and intermediate-distance windows, we obtain a subpercent precision determination of the light-quark-connected contribution to HVP of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mi>a</mi></mrow><mrow><mi>μ</mi></mrow><mrow><mi>l</mi><mi>l</mi></mrow></msubsup><mo stretchy="false">(</mo><mrow><mi>conn</mi></mrow><mo stretchy="false">)</mo><mo>=</mo><mn>655.2</mn><mo stretchy="false">(</mo><mn>2.3</mn><msub><mrow><mo stretchy="false">)</mo></mrow><mrow><mi>stat</mi></mrow></msub><mo stretchy="false">(</mo><mn>3.9</mn><msub><mrow><mo stretchy="false">)</mo></mrow><mrow><mi>syst</mi></mrow></msub><mo stretchy="false">[</mo><mn>4.5</mn><msub><mrow><mo stretchy="false">]</mo></mrow><mrow><mtext>total</mtext></mrow></msub><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>10</mn></mrow></msup></mrow></math>. Finally, as a consistency check, we verify that an independent analysis of the full contribution is in agreement with the sum of individual windows. We discuss our future plans for improvements of our HVP calculations to meet the target precision of the Fermilab <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>g</mi><mo>−</mo><mn>2</mn></math> experiment.

United States

Alexei Bazavov

Claude W. Bernard

David A. Clarke

United Kingdom

Christine Davies

Carleton DeTar

Aida X. El-Khadra

Elvira Gámiz

Steven Gottlieb

Anthony V. Grebe

Leon Hostetler

William I. Jay

Hwancheol Jeong

Andreas S. Kronfeld

Shaun Lahert

Jack Laiho

G. Peter Lepage

Michael Lynch

Andrew T. Lytle

Craig McNeile

Ethan T. Neil

Curtis T. Peterson

James N. Simone

Jacob W. Sitison

Ruth S. Van de Water

Alejandro Vaquero

Hadronic Vacuum Polarization for the Muon <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>g</mi><mo>−</mo><mn>2</mn></mrow></math> from Lattice QCD: Long-Distance and Full Light-Quark Connected Contribution

This study investigates the deflection of light, Einstein rings, thermal fluctuations, and tidal force and geodesic deviation in a loop quantum black hole (LQBH) resulting from gravitational collapse. Initially, we employ the Gauss–Bonnet theorem (GBT) to examine the weak deflection angle of the LQBH. For the GBT, we used the Gibbons-Werner method to obtain the Gaussian optical curvature. We also determined the deflection angle for a spherically symmetric BH in the context of the non-plasma and plasma environments under weak field constraints. Furthermore, we graphically investigate the deflection angle of light in the scenario of the impact parameter and find that the impact parameter has a direct effect on the angle. Later, we compute the Einstein rings of the LQBH and examine the graphical impact of various parameters. Moreover, we employ corrected entropy to examine the effects of thermal fluctuations for small and large BHs. For both large and small BHs, we examine the impact of the correction terms on the thermodynamic system. We also study the geodesic deviation in LQBH, with a particular emphasis on how quantum factors affect the paths of neighboring geodesics. Angular geodesics, in contrast to radial geodesics, tend to converge as one moves away from the BH, a phenomenon that reflects the complicated consequences of space-time curvature in this scenario.

Farzan Mushtaq

Xia Tiecheng

Faisal Javed

Bander Almutairi

Abdullo Hakimov

Impact of loop quantum gravity on gravitational lensing, thermal fluctuations, tidal force and geodesic deviation around a black hole

We point out that the odd-in-velocity contribution to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><msup><mi>G</mi><mn>4</mn></msup><mo stretchy="false">)</mo></math> radiated angular momentum for two-body scattering is determined by the radiation-reaction (RR) term in the one-loop waveform. This RR term is actually proportional to the tree-level waveform, and this reduces the calculation of the odd-in-velocity contribution to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><msup><mi>G</mi><mn>4</mn></msup><mo stretchy="false">)</mo></math> angular momentum loss, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>J</mi></mrow><mrow><mn>2</mn><mtext> </mtext><mtext> </mtext><mi>rad</mi></mrow></msub></mrow></math>, to two loops, instead of three loops as one would expect by power counting. We exploit this simplification, which follows from unitarity, to obtain a closed-form expression for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>J</mi></mrow><mrow><mn>2</mn><mtext> </mtext><mtext> </mtext><mi>rad</mi></mrow></msub></mrow></math> for generic velocities, which resums all fractional post-Newtonian (PN) corrections to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><msup><mi>G</mi><mn>4</mn></msup><mo stretchy="false">)</mo></math> angular momentum loss starting at 1.5PN.

France

Carlo Heissenberg

Radiation-reaction and angular momentum loss at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><msup><mrow><mi>G</mi></mrow><mrow><mn>4</mn></mrow></msup><mo stretchy="false">)</mo></mrow></math>

The low-energy spectrum relevant to the lattice calculation of the hadronic vacuum polarization contribution to muon anomalous magnetic moment <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>a</mi><mi>μ</mi><mrow><mi>HVP</mi><mo>,</mo><mi>LO</mi></mrow></msubsup></math> is dominantly given by two-pion states satisfying Lüscher’s finite-volume quantization condition. Finite-volume effects from those states may exhibit power-law dependence on the volume, contrary to an exponential suppression as suggested by chiral effective theory. Employing the finite-volume state decomposition of Euclidean correlators, we systematically investigate the volume dependence and identify the different volume scalings depending on the volume and Euclidean-time region. Using phenomenological inputs for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>π</mi><mi>π</mi></math> phase shift and the timelike pion form factor, we obtain an estimate for the finite-volume effects on <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>a</mi><mi>μ</mi><mrow><mi>HVP</mi><mo>,</mo><mi>LO</mi></mrow></msubsup></math>, which is consistent with previous works. Numerical results are given for the “window” observables of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>a</mi><mi>μ</mi></msub></math>.

Japan

Sakura Itatani

Hidenori Fukaya

Shoji Hashimoto

Anatomy of finite-volume effects on the hadronic vacuum polarization contribution to the muon <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>g</mi><mo>−</mo><mn>2</mn></math>

The motion of spinning particles around a quantum-corrected black hole is examined in this paper. We investigate the dynamics of spinning test particles by using the Mathisson–Papapetrou–Dixon equations, the Tulczyjew spin-supplementary condition, and restricting the motion to the equatorial plane. We determine the innermost stable circular orbit (ISCO), effective potential, and effective force and examine how these depend on the black hole’s $$\alpha $$ parameter and the particle’s $\textit{s}$ spin. However, we also take into account a superluminal bound on the motion of the spinning particle since its kinematical four-velocity and dynamical four-momentum are not always parallel. We also show how the parameter $$\alpha $$ affects the maximum value of the spin parameter $\textit{s}$. We determine the critical angular momentum of the particle for which a collision is possible by investigating collisions of spinning particles close to the horizon of a black hole. Finally, we compute the particle’s center-of-mass energy $$\mathcal {E}_{cm}$$ and analyze how the spin of the colliding particles affects it.

Ahmadjon Abdujabbarov

Impact of quantum-corrected parameter on spinning particle motion around a black hole