The particle origin of dark matter (DM) remains elusive despite decades of direct, indirect, and collider searches. Several groups have reported a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>γ</mi></math>-ray excess toward the Galactic Center commonly referred to as the Galactic Center excess (GCE). Its spectrum is consistent with annihilation of weakly interacting massive particles (WIMPs) of mass <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><mn>10</mn><mo>−</mo><mn>100</mn><mo stretchy="false">)</mo><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math> and a thermal-relic cross section. Although many concrete WIMP models reproduce the GCE spectrum, most are now excluded by direct detection experiments that are approaching the neutrino floor. We investigate a class of anomaly-free extensions of the Standard Model featuring gauged differences of lepton number, <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><msub><mi>L</mi><mi>i</mi></msub><mo>−</mo><msub><mi>L</mi><mi>j</mi></msub></mrow></msub></math>, and gauged baryon minus lepton number, <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>. We show that these models can reproduce the GCE while remaining compatible with the observed relic abundance. We then impose collider and direct detection constraints, accounting for both tree-level and loop-induced kinetic mixing. The <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>L</mi><mi>μ</mi></msub><mo>−</mo><msub><mi>L</mi><mi>e</mi></msub></math> model gives the best fit to the GCE: a DM mass of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>m</mi></mrow><mrow><mi>χ</mi></mrow></msub><mo>∼</mo><mn>40</mn><mo>−</mo><mn>50</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math> remains consistent with the muon and electron magnetic moment anomalies, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">(</mo><mi>g</mi><mo>−</mo><mn>2</mn><msub><mo stretchy="false">)</mo><mrow><mi>μ</mi><mo>,</mo><mi>e</mi></mrow></msub></math>, as well as current collider and direct detection limits, for mediator masses in the range <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>m</mi></mrow><mrow><msup><mrow><mi>A</mi></mrow><mrow><mo>′</mo></mrow></msup></mrow></msub><mo>∼</mo><mn>70</mn><mo>−</mo><mn>86</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math> and a DM mediator coupling of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mn>1</mn><mo>−</mo><mn>5</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></mrow></math>. By contrast, the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>L</mi><mi>e</mi></msub><mo>−</mo><msub><mi>L</mi><mi>τ</mi></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>L</mi><mi>μ</mi></msub><mo>−</mo><msub><mi>L</mi><mi>τ</mi></msub></math> models yield poorer fits; satisfying both the relic density and experimental bounds forces the DM mass to lie very close to resonance (i.e. approximately half the mediator mass). Finally, while the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo>−</mo><mi>L</mi></math> model also matches the GCE well, its parameter space is almost entirely ruled out by strong direct detection limits, except for the narrow resonance region where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>χ</mi></msub></math> should be equal to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><msup><mi>A</mi><mo>′</mo></msup></msub><mo>/</mo><mn>2</mn></math> requiring a fine-tuning at the few-percent level.

Italy

Jordan Koechler

Mattia Di Mauro

Leptophilic dark matter in <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><msub><mi>L</mi><mi>i</mi></msub><mo>−</mo><msub><mi>L</mi><mi>j</mi></msub></mrow></msub></math> models: A solution to the Fermi-LAT Galactic Center excess consistent with cosmological and laboratory observations

We construct backreacted geometries dual to the supersymmetric mass deformation of the IKKT matrix model. They are Euclidean type IIB supergravity solutions given in terms of an electrostatic potential, having SO(7) × SO(3) isometry and 16 supersymmetries. Quantizing the fluxes, we find that the supergravity solutions are in one-to-one correspondence with fuzzy sphere vacua of the matrix model.

Switzerland

Shota Komatsu

Adrien Martina

Joao Penedones

Antoine Vuignier

France

Xiang Zhao

Einstein gravity from a matrix integral. Part I

We propose a novel type of duality that connects a sequence of well-known theories with even-multiplicity scalar amplitudes: it relates the Yang-Mills theory coupled to a specific scalar matter sector to the nonlinear sigma model on a symmetric coset space, the (multiflavor) Dirac-Born-Infeld theory, and the special Galileon theory. The duality is manifested with the help of a covariant formulation of the classical equations of motion that features a contact quartic scalar self-coupling combined with propagation on a dynamical background of elementary or composite gauge fields. This is augmented with a set of constitutive relations that reflect the intrinsic or extrinsic geometry of the target space of the theory. The universality of the underlying geometric structure allows for an unambiguous mapping between different theories.

Norway

Tomáš Brauner

Netherlands

Yang Li

Diederik Roest

Tianzhi Wang

Geometric duality between effective field theories. Part I. Scattering amplitudes

We analyse electromagnetic leptogenesis within the framework of an effective field theory, where the dynamics is governed by the gauge-invariant dipole operator $${\mathcal{O}}_{NB}=\left(\overline{L}{\sigma }^{\mu \nu }N\right)\widetilde{H}{B}_{\mu \nu }$$ . The Wilson coefficient $\textit{C}$ is matched at one loop and evolved to the electroweak scale via renormalisation-group (RG) running. After electroweak symmetry breaking, we compute flavour-dependent decay widths and CP asymmetries for the two-body modes $\textit{N}$ → $\textit{νγ}$ and $\textit{N}$ → $\textit{νZ}$, and solve the fully flavoured Boltzmann equations. In the $\textit{N}$ -dominated regime, the freeze-out baryon asymmetry is $${Y}_{B}^{\text{FO}}\lesssim {1}{0}^{-{17}}$$ , far below the observed value $${Y}_{B}^{\text{obs}}\simeq 8.7\times {10}^{-11}$$ . The suppression is structural: gauge invariance forces a Higgs insertion; therefore the dipole coupling scales as $$\mu \propto v/{M}_{\psi}^{2}$$ , while the matched Wilson coefficient $\textit{C}$ is loop-generated and further suppressed by RG running. We note that in the quasi-degenerate limit the self-energy resonance can be operative and suggest a plausible path to $${Y}_{B}^{\text{obs}}$$ .

Japan

Rin Takada

Electromagnetic leptogenesis — an EFT-consistent analysis via Wilson coefficients. Part I. Low-scale, non-resonant regime

We perform the first computation of phase-transition parameters to cubic order in $ \lambda\sim m^2/T^2 $ , where $\textit{m}$ is the scalar mass and $\textit{T}$ is the temperature, in a simple model resembling the Higgs sector of the SMEFT. We use dimensional reduction, including 1-loop matching corrections for terms of dimension 6 (in 4-dimensional units), 2-loop contributions for dimension-4 ones and 3-loops for the squared mass. We precisely quantify the size of the different corrections, including renormalization-group running as well as quantum effects from light fields in the effective theory provided by the Coleman-Weinberg potential, and discuss briefly the implications for gravitational waves. Our results suggest that, for strong phase transitions, 1-loop corrections from dimension-6 operators can compete with 2-loop ones from quartic couplings and largely surpass those from 3-loop thermal masses.

Spain

Mikael Chala

Luis Gil

Zhe Ren

Phase transitions in dimensional reduction up to three loops * Supported by MCIN/AEI (10.13039/501100011033) and ERDF (grants PID2021-128396NB-I00 and PID2022-139466NB-C22), from the Junta de Andalucía grants FQM 101 and P21-00199 and from Consejería de Universidad, Investigación e Innovación, Gobierno de España and Unión Europea – NextGenerationEU under grants AST22 6.5 and CNS2022-136024. MC and LG are further supported by the RyC and FPU programs under contract numbers RYC2019-027155-I and FPU23/02026, respectively.

In this work, we explore the cosmological dynamics of a modified gravity framework based on the function $$f(Q,B)=\delta Q^{2}+\beta B$$ , where $\textit{Q}$ denotes the nonmetricity scalar and $\textit{B}$ is the boundary term that relates $\textit{Q}$ to the Ricci scalar. The matter sector is modeled using the Modified Chaplygin Gas (MCG) with the equation of state $$p=A\rho -\frac{D_{1}}{\rho ^{\alpha }}$$ , allowing the model to interpolate between early-time matter behavior and late-time cosmic acceleration. By deriving an analytical expression for the Hubble parameter $\textit{H}$($\textit{z}$), we perform a parameter estimation using Markov Chain Monte Carlo (MCMC) techniques in conjunction with the latest cosmological observations: 46 Hubble parameter measurements, 15 BAO data points, DESI DR2 BAO data and the Pantheon+ Type Ia supernovae compilation. The best-fit values are obtained as $$H_0=72.2814^{+3.4702}_{-4.5209}$$ km/s/Mpc, $$A_s = 0.6964^{+0.0779}_{-0.1258}$$ , $$\alpha = 0.0027^{+0.0225}_{-0.0209}$$ and $$A = 0.0024^{+0.0702}_{-0.0464}$$ . The deceleration parameter transitions at redshift $$z_{tr} \approx 0.946$$ , while the present-day value is $$q_0 = -0.789$$ . The model yields an age of the Universe $$t_0 \approx 13.53$$ Gyr and a present EoS parameter $$\omega _0 \approx -0.691$$ , which reflects the late-time acceleration consistent with observational bounds. These results demonstrate that the MCG scenario within $\textit{f}$($\textit{Q}$, $\textit{B}$) gravity provides a viable and observationally consistent framework for explaining the late-time accelerated expansion of the Universe.

India

Amit Samaddar

S. Singh

A new parametric study of $\textit{f}$($\textit{Q}$, $\textit{B}$) gravity with modified Chaplygin gas and recent observations

The anisotropic distribution of ultra high energy cosmic rays (UHECRs) remains a compelling and deeply informative observable in astro-particle physics, illuminating their enigmatic origins, extreme acceleration processes, and trajectories shaped by the cosmic large-scale structure. Among the hierarchy of anisotropy modes, the dipole stands out as a particularly sensitive tracer reflecting both the spatial configuration of sources and the foundational cosmological model. In this work, we conduct a rigorous comparative analysis of dipolar anisotropy within the diffusive propagation regime, evaluating its evolution across three gravitational framework: the standard ΛCDM model, a power-law extension of <italic>f</italic>( <italic>R</italic>) modified gravity, and the Starobinsky inflationary scenario. Our objective is to disentangle the gravitational signatures embedded in UHECR anisotropy, with particular emphasis on deviations arising from extended theories of gravity within the <italic>f</italic>( <italic>R</italic>) formalism. The results reveal a striking dependence on the underlying gravitational paradigm: the power-law model predicts significantly enhanced anisotropies, &#923;CDM consistently produces the most suppressed amplitudes, and the Starobinsky model exhibits an intermediate profile with partial convergence toward &#923;CDM. These findings reinforce the notion that UHECR anisotropy is not merely a reflection of astrophysical processes, but also a subtle messenger of the fundamental gravitational laws governing the universe offering a novel and promising avenue for testing physics beyond the standard cosmological framework.

Pakistan

Iftikhar Ahmad

Muhammad Mahtisham

Azerbaijan

China

Adnan Malik

Saudi Arabia

Fatemah Mofarreh

Model-dependent predictions for UHECR dipolar anisotropies in a <italic>f</italic>( <italic>R</italic>) modified gravity

General Relativity (GR) is not the only way gravity can be geometrized. Instead of curvature, the Teleparallel Theory attributes gravity to the torsion <italic>T</italic>, which is related to the antisymmetric part of the connection. On the other hand, the Symmetric Teleparallel Theory no longer preserves metricity, describing gravity through the non-metricity tensor <italic>Q<inf>&#945;&#956;&#957;</inf></italic>&#8239;&#8801;&#8239;&#8711; <inf><italic>&#945;</italic></inf> <italic>g<inf>&#956;&#957;</inf></italic>. These descriptions give form to what is known as geometrical trinity of gravity. Recently, the extensions of GR have been intensively investigated in order to solve the theoretical impasses which have arisen. In this sense, it is also useful to investigate the extensions of alternative descriptions of gravity, which leads us to the so-called <italic>f</italic>( <italic>T</italic>) and <italic>f</italic>( <italic>Q</italic>) gravities. In this paper, we consider a family of <italic>f</italic>( <italic>Q</italic>) models and obtain their corresponding Tolman-Oppenheimer-Volkoff equations applied to polytropic stars. It is worth mentioning that the <italic>f</italic>( <italic>Q</italic>) covariant formulation is adopted and we present a new equation that substantially simplifies the numerical calculations. Using numerical integration, it is possible to solve a system of differential equations to calculate, among other things, the maximum mass and mass-radius relation allowed. In addition, we explicitly show the non-metricity behavior inside and outside the star.

Brazil

J.C.N. de Araujo

H.G.M. Fortes

Polytropic stars in <math altimg='si11.svg'><mrow><mi>f</mi><mrow><mo>(</mo><mi>Q</mi><mo>)</mo></mrow><mo linebreak='goodbreak'>=</mo><mi>Q</mi><mo linebreak='goodbreak'>+</mo><mi>&#958;</mi><msup><mi>Q</mi><mn>2</mn></msup></mrow></math> covariant formulation

We perform a comprehensive investigation of the radiative decays of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>P</mi></math>-wave charmed baryons in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi><mi>U</mi><mo stretchy="false">(</mo><mn>3</mn><mo stretchy="false">)</mo></math> flavor <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mn mathvariant="bold">6</mn></mrow><mrow><mi>F</mi></mrow></msub></mrow></math> representation, employing the light-cone quantum chromodynamics (QCD) sum rule approach within the framework of heavy quark effective theory. We analyze their electromagnetic transitions into ground-state charmed baryons via photon emission. When combined with the mass spectra and strong decay properties previously studied in Yang and Chen [<a href="http://dx.doi.org/10.1103/PhysRevD.104.034037">Phys. Rev. D 104, 034037 (2021)</a>], our results constitute a systematic and complete QCD sum rule analysis of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>P</mi></math>-wave singly charmed baryons within the framework of heavy quark effective theory. As summarized in Table V, several excited charmed baryons are found to possess suppressed strong decay widths, thereby rendering their radiative decay channels particularly significant for experimental identification and theoretical understanding.

Xuan Luo

Hua-Xing Chen

Er-Liang Cui

Hui-Min Yang

Dan Zhou

Zhi-Yong Zhou

Radiative decays of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>P</mi></mrow></math>-wave charmed baryons in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi><mi>U</mi><mo stretchy="false">(</mo><mn>3</mn><mo stretchy="false">)</mo></math> flavor <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mn>6</mn><mi mathvariant="normal">F</mi></msub></math> representation

Baryogenesis refers to the physical process responsible for generating the observed baryon asymmetry in the early universe. The presence of a nonzero baryon number density suggests a surplus of matter over antimatter. In this study, a novel approach is proposed to verify the direct consequences of late-time observations on gravitational baryogenesis. The incorporation of two key data sets, DESI and gravitational wave observations, makes the analysis more intriguing. In the teleparallel framework, the methodology connects the primordial time to the late time. The intermediating epochs are also investigated with the help of the deceleration parameter. Our results show that the net remaining asymmetry yields a baryon-to-entropy ratio in excellent agreement with observations.

Sai Swagat Mishra

N.S. Kavya

P.K Sahoo

Effects of DESI and GW observations on <italic>f</italic>( <italic>T</italic>) gravitational baryogenesis