This study explores the structure of compact stars using an extended theory of gravity known as <math altimg='si1.svg'><mi>f</mi><mo stretchy='false'>(</mo><mi mathvariant='script'>R</mi><mo>,</mo><mi mathvariant='script'>G</mi><mo>,</mo><mi mathvariant='script'>T</mi><mo stretchy='false'>)</mo></math> gravity, where <math altimg='si3.svg'><mi mathvariant='script'>R</mi></math>, is the Ricci scalar, <math altimg='si4.svg'><mi mathvariant='script'>G</mi></math>, the Gauss-Bonnet invariant, and <math altimg='si5.svg'><mi mathvariant='script'>T</mi></math> the trace of the energy-momentum tensor. Focusing on massive radio pulsars, specifically neutron stars with masses greater than 1.8 solar masses, utilize these extreme astrophysical environments to test gravity in regimes unreachable by Earth-based experiments. We adopt a linear form of the theory, <math altimg='si18.svg'><mi>f</mi><mo stretchy='false'>(</mo><mrow><mi mathvariant='script'>R</mi><mo>,</mo><mi mathvariant='script'>G</mi><mo>,</mo><mi mathvariant='script'>T</mi></mrow><mo stretchy='false'>)</mo><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mi mathvariant='script'>R</mi><mo linebreak='goodbreak' linebreakstyle='after'>+</mo><mi>&#945;</mi><mi mathvariant='script'>G</mi><mo linebreak='goodbreak' linebreakstyle='after'>+</mo><mi>&#946;</mi><mi mathvariant='script'>T</mi></math>, with <italic>&#945;</italic>, <cross-ref refid='fn0010' id='crf0390'>1</cross-ref> and <italic>&#946;</italic> are dimensional constants, and derive an exact analytical solution for anisotropic perfect fluid spheres in hydrostatic equilibrium. This model incorporates the compactness factor <math altimg='si7.svg'><mi>C</mi><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mfrac><mrow><mn>2</mn><mi>G</mi><mi>M</mi></mrow><mrow><mi>R</mi><msup><mrow><mi>c</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></mfrac></math>, to describe all physical properties within the stellar interior. To constrain the model, we employ observational data from the pulsar <italic>U</italic>1724, using its mass and radius to fix the parameters at their upper bounds: <math altimg='si8.svg'><msub><mrow><mi>&#945;</mi></mrow><mrow><mn>1</mn></mrow></msub><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mfrac><mrow><mi>&#945;</mi></mrow><mrow><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></mfrac><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mo>&#177;</mo><mn>0.023</mn></math> and <math altimg='si9.svg'><msub><mrow><mi>&#946;</mi></mrow><mrow><mn>1</mn></mrow></msub><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mfrac><mrow><mi>&#946;</mi></mrow><mrow><msup><mrow><mi>&#954;</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></mfrac><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mo>&#177;</mo><mn>0.001</mn></math>. The resulting model is consistent with physical viability and observational constraints. Notably, the squared sound speed in this framework remains below the theoretical limit ( <math altimg='si10.svg'><mmultiscripts><mrow><mtext mathvariant='normal'>c</mtext></mrow><mrow><mi>s</mi></mrow><none /><none /><mrow><mn>2</mn></mrow></mmultiscripts><mo linebreak='goodbreak' linebreakstyle='after'>&lt;</mo><msup><mrow><mi>c</mi></mrow><mrow><mn>2</mn></mrow></msup><mo stretchy='false'>/</mo><mn>3</mn></math>), contrasting with general relativity results. Without assuming a specific equation of state, the model exhibits linear behavior and predicts a core density several times higher than nuclear saturation density ( <math altimg='si11.svg'><msub><mrow><mi>&#961;</mi></mrow><mrow><mtext>nuc</mtext></mrow></msub><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>2.6</mn><mo>&#215;</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>14</mn></mrow></msup></math> g/cm 3), with surface density <math altimg='si12.svg'><msub><mrow><mi>&#961;</mi></mrow><mrow><mi>s</mi></mrow></msub></math>, also exceeding this threshold. Additionally, the derived mass-radius relation agrees well with existing astrophysical observations.

Egypt

South Africa

G.G.L. Nashed

Constraining linear form of <math altimg='si1.svg'><mi>f</mi><mo stretchy='false'>(</mo><mrow><mi mathvariant='script'>R</mi><mo>,</mo><mi mathvariant='script'>G</mi><mo>,</mo><mi mathvariant='script'>T</mi></mrow><mo stretchy='false'>)</mo></math> gravity from astrophysical observations of the Pulsar U1724

We consider the effects of a local axion dark matter background on $\textit{g}$ − 2 of the electron. We calculate loop corrections to the photon-electron vertex and determine analytical formulas for the spin and cyclotron frequencies when the electron is in an external magnetic field. By comparing with current measurements of these observables, we are able to place the strongest constraint on the axion-elecron coupling for axion masses below 3 × 10 eV.

China

Ariel Arza

Jason Evans

Electron $\textit{g −}$ 2 corrections from axion dark matter

Non-geometric flux vacua have recently been revisited, leading to the remarkable discovery of isolated 4D $$ \mathcal{N} $$ = 1 supersymmetric Minkowski vacua. These constructions rely on the non-renormalization of the superpotential, which is supported by heuristic arguments. Given the significance of verifying the existence of these isolated M-theory-like vacua, we present alternative symmetry-based arguments that arrive at the same conclusion. Additionally, we leverage these symmetries to argue for the existence of unstable dS solutions as well as supersymmetric AdS solutions.

United States

Shi Chen

Damian Heisteeg

Cumrun Vafa

Symmetries and M-theory-like vacua in four dimensions

The ALPHA-g experiment at CERN aims to precisely measure the terrestrial gravitational acceleration of antihydrogen atoms. A radial Time Projection Chamber (rTPC), that surrounds the ALPHA-g magnetic trap, is employed to determine the annihilation location, called the vertex. The standard approach requires identifying the trajectories of the ionizing particles in the rTPC from the location of their interaction in the gas (spacepoints), and inferring the vertex positions by finding the point where those trajectories (helices) pass closest to one another. In this work, we present a novel approach to vertex reconstruction using an ensemble of models based on the PointNet deep learning architecture. The newly developed model, PointNet Ensemble for Annihilation Reconstruction (PEAR), directly learns the relation between the location of the vertices and the rTPC spacepoints, thus eliminating the need to identify and fit the particle tracks. PEAR shows strong performance in reconstructing vertical vertex positions from simulated data, that is superior to the standard approach for all metrics considered. Furthermore, the deep learning approach can reconstruct the vertical vertex position when the standard approach fails.

Canada

A. Ferreira

M. Singh

Y. Saito

A. Capra

I. Carli

D. Duque Quiceno

W. Fedorko

M. Fujiwara

M. Li

L. Martin

G. Smith

A. Xu

Antimatter annihilation vertex reconstruction with deep learning for ALPHA-g radial Time Projection Chamber

In this paper, we analyze the potential variation of the gravitational constant <italic>G</italic> using data from strong gravitational lensing systems and Type Ia supernovae. Testing <math altimg='si1.svg'><mi>G</mi><mo stretchy='false'>(</mo><mi>z</mi><mo stretchy='false'>)</mo></math> parameterizations where <math altimg='si2.svg'><mi>G</mi><mo stretchy='false'>(</mo><mi>z</mi><mo stretchy='false'>)</mo><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><msub><mrow><mi>G</mi></mrow><mrow><mn>0</mn></mrow></msub><mo stretchy='false'>(</mo><mn>1</mn><mo linebreak='badbreak' linebreakstyle='after'>+</mo><msub><mrow><mi>G</mi></mrow><mrow><mn>1</mn></mrow></msub><mi>z</mi><mo stretchy='false'>)</mo></math> and <math altimg='si3.svg'><mi>G</mi><mo stretchy='false'>(</mo><mi>z</mi><mo stretchy='false'>)</mo><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><msub><mrow><mi>G</mi></mrow><mrow><mn>0</mn></mrow></msub><msup><mrow><mo stretchy='false'>(</mo><mn>1</mn><mo linebreak='badbreak' linebreakstyle='after'>+</mo><mi>z</mi><mo stretchy='false'>)</mo></mrow><mrow><msub><mrow><mi>G</mi></mrow><mrow><mn>1</mn></mrow></msub></mrow></msup></math>, we also account for the influence of <italic>G</italic> on the luminosity of SNe Ia through the Chandrasekhar mass-luminosity relation. Only the flat universe hypothesis is considered. Constraints from 158 lensing systems and the Pantheon+ sample show no significant evidence of <italic>G</italic> variation. However, although the results are compatible with no variation, the errors are not yet sufficiently restrictive to rule out any variation of <italic>G</italic> with high statistical confidence. This study highlights the viability of using combined astrophysical data to probe variations in fundamental constants, suggesting that future surveys could refine these constraints.

Brazil

R.F.L. Holanda

Marcelo Ferreira

Javier E. Gonzalez

An investigation of a varying G through Strong Lensing and SNe Ia observations

In this work we investigate the muon anomalous magnetic dipole moment <math altimg='si1.svg'><msub><mrow><mi>a</mi></mrow><mrow><mi>&#956;</mi></mrow></msub></math> in a model that extends the Standard Model with a scalar triplet and a lepton triplet. Different from previous studies, we find that there is still viable parameter space in this model to explain the discrepancy <math altimg='si2.svg'><mi mathvariant='normal'>&#916;</mi><msub><mrow><mi>a</mi></mrow><mrow><mi>&#956;</mi></mrow></msub><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><msub><mrow><mi>a</mi></mrow><mrow><mi>&#956;</mi></mrow></msub><mo stretchy='false'>(</mo><mrow><mi mathvariant='normal'>Exp</mi></mrow><mo stretchy='false'>)</mo><mo linebreak='goodbreak' linebreakstyle='after'>&#8722;</mo><msub><mrow><mi>a</mi></mrow><mrow><mi>&#956;</mi></mrow></msub><mo stretchy='false'>(</mo><mrow><mi mathvariant='normal'>SM</mi></mrow><mo stretchy='false'>)</mo></math>. While being consistent with the current data of neutrino mass, electroweak precision measurements and the perturbativity of couplings, our model can provide new physics contribution <math altimg='si128.svg'><msubsup><mrow><mi>a</mi></mrow><mrow><mi>&#956;</mi></mrow><mrow><mtext mathvariant='normal'>NP</mtext></mrow></msubsup></math> to cover the central region of <math altimg='si18.svg'><mi mathvariant='normal'>&#916;</mi><msub><mrow><mi>a</mi></mrow><mrow><mi>&#956;</mi></mrow></msub></math> with new scalar and lepton mass as low as around TeV. This mass scale is allowed by the current collider searches for doubly charged scalars and the lepton triplet, and they can be tested at future high energy and/or high luminosity colliders.

Lei Cai

South Korea

Chengcheng Han

Shi-Ping He

Peiwen Wu

Hybrid Type-II and Type-III seesaw model for the muon <italic>g</italic>&#8239;&#8722;&#8239;2 anomaly

In order to reach a precision of 0$\textit{.}$2% on the hadronic vacuum polarization (HVP) contribution to the anomalous magnetic moment of the muon, ($\textit{g}$ – 2) , such that the full Standard-Model prediction matches in precision the direct experimental measurement, it is crucial to include the leading, O($\textit{α}$) electromagnetic corrections to HVP. In this work, we determine an important contribution to the latter from a diagram comprised of two two-point quark-loops, connected by the internal photon and gluons. This ultraviolet-finite correction is calculated from lattice QCD using a coordinate-space formalism, where photons are treated in the continuum and infinite volume. Our result amounts to a (−0.89 ± 0.18)% correction to the leading-order HVP contribution to ($\textit{g}$ – 2) . To overcome the worsening statistical noise at large distances, our analysis is combined with phenomenological models featuring light pseudoscalar mesons with masses below 1 GeV. In particular, our data show a very steep mass dependence as dictated by the charged pion loop. Similarly, the other diagrams appearing in the O($\textit{α}$)-corrections to the HVP with the internal photon connecting two separate quark loops are also ultraviolet-finite and can be computed with the same formalism.

Germany

Julian Parrino

Volodymyr Biloshytskyi

En-Hung Chao

Harvey Meyer

Vladimir Pascalutsa

Computing the UV-finite electromagnetic corrections to the hadronic vacuum polarization in the muon ($\textit{g}$ − 2) from lattice QCD

Big Bang nucleosynthes describes a significant process in the early universe, responsible for the formation of light nuclei a while after the Big Bang explosion. Its sensitivity to the expansion rate makes BBN an effective probe for testing deviations from standard cosmology, particularly within the framework of modified theories of gravity. In this article, we investigate the evolution of the Universe through Big Bang nucleosynthesis within the framework of <math altimg='si2.svg'><mi>f</mi><mo stretchy='false'>(</mo><mi>T</mi><mo>,</mo><mspace width='0.25em' /><mi>B</mi><mo>,</mo><mspace width='0.25em' /><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant='script'>G</mi></mrow></msub><mo>,</mo><mspace width='0.25em' /><msub><mrow><mi>B</mi></mrow><mrow><mi mathvariant='script'>G</mi></mrow></msub><mo stretchy='false'>)</mo></math> gravity. Here, <math altimg='si3.svg'><mi>T</mi><mo>,</mo><mspace width='0.25em' /><mi>B</mi><mo>,</mo><mspace width='0.25em' /><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant='script'>G</mi></mrow></msub></math> and <math altimg='si4.svg'><msub><mrow><mi>B</mi></mrow><mrow><mi mathvariant='script'>G</mi></mrow></msub></math> correspond to the torsion, boundary term, teleparallel Gauss-Bonnet term, and Gauss-Bonnet boundary term, respectively. To explore the deviation from the teleparallel equivalent of general relativity, we apply the transformation <math altimg='si2.svg'><mi>f</mi><mo stretchy='false'>(</mo><mi>T</mi><mo>,</mo><mspace width='0.25em' /><mi>B</mi><mo>,</mo><mspace width='0.25em' /><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant='script'>G</mi></mrow></msub><mo>,</mo><mspace width='0.25em' /><msub><mrow><mi>B</mi></mrow><mrow><mi mathvariant='script'>G</mi></mrow></msub><mo stretchy='false'>)</mo></math> = <math altimg='si5.svg'><mo linebreak='badbreak' linebreakstyle='after'>&#8722;</mo><mi>T</mi><mo linebreak='goodbreak' linebreakstyle='after'>+</mo><mi mathvariant='script'>F</mi><mo stretchy='false'>(</mo><mi>T</mi><mo>,</mo><mspace width='0.25em' /><mi>B</mi><mo>,</mo><mspace width='0.25em' /><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant='script'>G</mi></mrow></msub><mo>,</mo><mspace width='0.25em' /><msub><mrow><mi>B</mi></mrow><mrow><mi mathvariant='script'>G</mi></mrow></msub><mo stretchy='false'>)</mo></math>. For an in-depth analysis of the Big Bang nucleosynthesis, we choose five distinct models from gravity and compared the results with the observational limits on <math altimg='si6.svg'><mo stretchy='true'>|</mo><mfrac><mrow><mi mathvariant='normal'>&#916;</mi><msub><mrow><mi mathvariant='script'>T</mi></mrow><mrow><mi>f</mi></mrow></msub></mrow><mrow><msub><mrow><mi mathvariant='script'>T</mi></mrow><mrow><mi>f</mi></mrow></msub></mrow></mfrac><mo stretchy='true'>|</mo></math> to examine restrictions on the free parameters associated with these models. Our outcomes indicate that <math altimg='si2.svg'><mi>f</mi><mo stretchy='false'>(</mo><mi>T</mi><mo>,</mo><mspace width='0.25em' /><mi>B</mi><mo>,</mo><mspace width='0.25em' /><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant='script'>G</mi></mrow></msub><mo>,</mo><mspace width='0.25em' /><msub><mrow><mi>B</mi></mrow><mrow><mi mathvariant='script'>G</mi></mrow></msub><mo stretchy='false'>)</mo></math> gravity can agree with the constraint of big bang nucleosynthesis, and hence build a valid view of the universe. Moreover, we take the limiting cases of the assumed theory, that is, <math altimg='si7.svg'><mi>f</mi><mo stretchy='false'>(</mo><mi>T</mi><mo>,</mo><mi>B</mi><mo stretchy='false'>)</mo></math> and <math altimg='si8.svg'><mi>f</mi><mo stretchy='false'>(</mo><mi>T</mi><mo stretchy='false'>)</mo></math> theories, which also ensure consistency with BBN data.

Pakistan

Abdul Malik Sultan

Manahil Ali

Shamaila Rani

Azerbaijan

Nadeem Azhar

Kazakhstan

N. Myrzakulov

Uzbekistan

Sanjar Shaymatov

Constraining Big Bang nucleosynthesis in <math altimg='si1.svg'><mi>f</mi><mo stretchy='false'>(</mo><mi>T</mi><mo>,</mo><mi>B</mi><mo>,</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant='script'>G</mi></mrow></msub><mo>,</mo><msub><mrow><mi>B</mi></mrow><mrow><mi mathvariant='script'>G</mi></mrow></msub><mo stretchy='false'>)</mo></math> gravity

The arguably most promising avenue towards testing physics beyond the Standard Model in the anomalous magnetic moment of the $\textit{τ}$ proceeds via suitably constructed asymmetries in $\textit{e}$ $\textit{e}$ → $\textit{τ}$ $\textit{τ}$ in the presence of a polarized electron beam. Such a program, as could be realized at Belle II assuming a polarization upgrade of the SuperKEKB $\textit{e}$ $\textit{e}$ collider, crucially relies on a careful consideration of radiative corrections. In this work, we present the complete one-loop result for the fully polarized $\textit{e}$ $\textit{e}$ → $\textit{τ}$ $\textit{τ}$ process and its implementation in the Monte-Carlo integrator M M . As an application, we discuss projections relevant for measurements at Belle II, both with and without electron polarization, and outline the necessary steps for a generalization to next-to-next-to-leading order.

Switzerland

Joël Gogniat

Martin Hoferichter

United Kingdom

Yannick Ulrich

Towards testing ($\textit{g}$ − 2)

Motivated by the updated analysis of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>G</mi><mo stretchy="false">(</mo><mn>3900</mn><mo stretchy="false">)</mo></math> by the BESIII Collaboration, we perform a global analysis of the cross sections of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><mo stretchy="false">→</mo><mi>D</mi><mover accent="true"><mrow><mi>D</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><mo stretchy="false">→</mo><mi>D</mi><msup><mrow><mover accent="true"><mrow><mi>D</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover></mrow><mrow><mo>*</mo></mrow></msup><mo>+</mo><mi mathvariant="normal">c</mi><mo>.</mo><mi mathvariant="normal">c</mi><mo>.</mo></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mo stretchy="false">→</mo><msup><mi>D</mi><mo>*</mo></msup><msup><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover><mo>*</mo></msup></math> processes, especially focusing on the properties of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>G</mi><mo stretchy="false">(</mo><mn>3900</mn><mo stretchy="false">)</mo></math>. As the energy region of interest is limited by the next opening threshold, i.e., the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>D</mi><mn>1</mn></msub><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover></math> threshold, we focus on the energy region [3.7, 4.25] GeV, where three charmonia <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>1</mn><mi>D</mi><mo stretchy="false">)</mo></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>3</mn><mi>S</mi><mo stretchy="false">)</mo></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>D</mi><mo stretchy="false">)</mo></math> explicitly contribute to the cross sections. By constructing the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>P</mi></math>-wave contact interaction between the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">(</mo><mi>D</mi><mo>,</mo><msup><mi>D</mi><mo>*</mo></msup><mo stretchy="false">)</mo></math> doublet and its antiparticle in the heavy quark limit, we extract the physical scattering amplitude by solving the Lippmann-Schwinger equation. No matter whether three or two charmonium states are included in our framework, we always find a dynamically generated state corresponding to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>G</mi><mo stretchy="false">(</mo><mn>3900</mn><mo stretchy="false">)</mo></math>, which suggests it to be a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>P</mi></math>-wave dynamically generated state. We also predict several dynamically generated states in the corresponding <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mn>1</mn><mrow><mo>−</mo><mo>+</mo></mrow></msup></math> channel. These states can be further searched for in the electron-positron annihilation process involving the emission of a single photon.

Quanxing Ye

Zhenyu Zhang

Meng-Lin Du

Ulf-G. Meißner

Peng-Yu Niu

Japan

Qian Wang

Resonance parameters of the vector charmoniumlike state <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>G</mi><mo stretchy="false">(</mo><mn>3900</mn><mo stretchy="false">)</mo></math>