<p>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.</p>

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 <i>Fermi</i>-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.

It is well known that a weak gravity limit can be associated with a restoration of Lorentz covariance. In this paper we present a physical example of a parity-even Einstein–Cartan domain wall (ECDW) embedded in a Weitzenböck zero connection vacuum manifold in the weak torsion gravity limit. Off the wall, the manifold is almost Minkowskian, and the teleparallel equivalent of general relativity is restored (TEGR). ECDW non-dynamical torsion gravity implies that the regions off the wall would naturally be Minkowskian. Thus, our generalization here is used for a parity-even ECDW in Weitzenböck geometry to allow for coupling the wall to the weak gravitational waves in teleparallel gravity. Recently, Li et al. reported giving up Weitzenböck geometry, and they also argued that local Lorentz invariance (LLI) does not affect experiments. But here we argue that in these lab experiments, weak Weitzenböck gravity is used and the specific ECDW embedded in the Weitzenböck manifold vacuum can be considered equivalent to GR (TEGR). Since conformal Bianchi type I metrics are in general not Bianchi I, we do not address here the use of the proper Weitzenböck frame instead of the orthonormal frame which introduces the local covariance violation.

Brazil

Croatia

L. Andrade

Restoring Lorentz symmetries in parity-even Einstein–Cartan domain walls conformal to Bianchi I metric embedded in weak gravity Weitzenböck vacuum manifold

The present paper is the first installment where, extending our previous work in pure Yang–Mills (YM) theory, we compute the generating functional of correlators of collinear twist-2 operators that enter the components of balanced superfields – i.e., superfields with an equal number of dotted and undotted indices in their spinor representation – in $$\mathscr {N} = 1$$ SUSY SU($\textit{N}$) YM theory in Minkowskian and Euclidean space-time, in the conformal limit and renormalization-group (RG) improved form, and to the leading and next-to-leading order in the large-$\textit{N}$ expansion. Moreover, we compare our asymptotic RG-improved generating functional to the next-to-leading large-$\textit{N}$ order with the corresponding nonperturbative object arising from the glueball/gluinoball one-loop effective action, which it should be asymptotic to at short distances because of the asymptotic freedom. Remarkably, we find that both have the structure of the logarithm of a functional superdeterminant. Hence, our large-$\textit{N}$ computation sets strong ultraviolet asymptotic constraints on the nonperturbative solution of large-$\textit{N}$ $$\mathscr {N} = 1$$ SUSY YM theory that may be a pivotal guide for the search of such a solution.

Marco Bochicchio

Mauro Papinutto

Francesco Scardino

Generating functional of correlators of twist-2 operators in $$\mathscr {N} = 1$$ SUSY Yang–Mills theory, I

This study is concern to the homothetic symmetry approach to get exact solutions for locally rotationally symmetric (LRS) Bianchi type-I spacetimes within the framework of <math altimg='si108.svg'><mrow><mi>f</mi><mo>(</mo><mi>R</mi><mo>)</mo></mrow></math> gravity, revealing that such spacetimes posses homothetic symmetry of different dimensions. By employing the Rif tree algorithm implemented in Maple, we systematically transform the symmetry and field equations into a set of constraints on the metric functions, enabling the derivation of exact analytical forms for the homothetic vector fields. Furthermore, we compute the corresponding physical quantities, including the energy density <math altimg='si109.svg'><mi>&#961;</mi></math>, pressure <math altimg='si110.svg'><mi>p</mi></math>, Ricci scalar <math altimg='si111.svg'><mi>R</mi></math>, shear scalar <math altimg='si8.svg'><msup><mi>&#963;</mi><mn>2</mn></msup></math>, equation of state <math altimg='si112.svg'><mi>w</mi></math> and modified gravity function <math altimg='si113.svg'><mrow><mi>F</mi><mo>(</mo><mi>r</mi><mo>)</mo></mrow></math>, for each solution, providing crucial insights into the geometric and physical properties of these spacetimes within the <math altimg='si107.svg'><mrow><mi>F</mi><mo>(</mo><mi>R</mi><mo>)</mo></mrow></math> gravity.

Pakistan

Jamshed Khan

Sumaira Saleem Akhtar

Ambreen Ayub

Exact LRS Bianchi type I solutions in quadratic <math altimg='si107.svg'><mrow><mi>F</mi><mo>(</mo><mi>R</mi><mo>)</mo></mrow></math> gravity from homothetic symmetries: A Rif tree approach

In this paper, we continue our investigation of gravitational interactions for massive higher spins extending our previous work on massive spin 3/2 and spin 2 to massive spin 5/2, including partially massless and massless limits. We use the gauge invariant frame-like description for massive fields, both for general analysis of possible vertices and for constructing the minimal vertex (i.e. vertex containing standard minimal interactions and non-minimal interactions with a minimum number of derivatives). In particular, we show that there is a special point $\textit{m}$ = 4Λ, which corresponds to the boundary of a unitary allowed region in $\textit{dS}$ , where minimal interactions disappear, leaving only non-minimal ones.

Russia

Yu. Zinoviev

On massive higher spins and gravity. Part I. Spin 5/2

This work considers the dynamics of the gauge vector and inflaton (dilaton) fields inspired by Kaluza–Klein theory in an inflationary universe with Bianchi type-I spacetime. The inverse power-law potential of the inflaton field is used to study dynamical system analysis. As a result, all fixed points in the autonomous system are non-hyperbolic fixed points, and one cannot determine their stability. Therefore, a center manifold theory is required to analyze the stability of the dynamical system properly. Interestingly, we found an isotropic attractor point which means that the universe undergoes accelerated expansion (inflation) from an anisotropic phase to an isotropic phase of the universe. According to the dynamical system analysis of the anisotropic Bianchi type-I universe with the inspired Kaluza–Klein model, our results supported the isotropization of the observed universe.

Thailand

Jaturaporn Watanakampolkij

Patinya Ma-ardlerd

Natthason Autthisin

Pornpatara Chuvala

Nutthaphat Lunrasri

Chakrit Pongkitivanichkul

Daris Samart

Kaluza–Klein inspired a model of the inflation with the inverse power law potential in Bianchi type-I universe