Electroweak (EW) amplitudes in the gauge-Goldstone five-component formalism have a distinctive property: gauge symmetry is imprinted in the amplitudes, manifested as the massive Ward identity (MWI) $ k^M{\cal{M}}_M=0 $ . In this study, we used the HELAS package to numerically study gauge symmetry in EW amplitudes. First, we directly tested gauge symmetry by examining the MWI of amplitudes. Second, we modified the couplings within a vertex and among vertices to check if and how the MWI changes. Third, we tested gauge symmetry by considering the couplings modified by operators from the standard model effective field theory (SMEFT). Similar to the standard model, there are relations between different couplings that are protected by gauge symmetry. We observed that, if we modify the couplings to deviate from the relations, the MWI is violated. In contrast, the MWI is restored when the relations between couplings reduce to those in the SMEFT.

China

Wang-Fa Li

Junmou Chen

Qian-Jiu Wang

Zhao-Huan Yu

Numerical study on the gauge symmetry of electroweak amplitudes * Junmou Chen is supported by National Natural Science Foundation of China (12205118), Wang-Fa Li, Qian-Jiu Wang, and Zhao-Huan Yu are supported by the Guangzhou Science and Technology Planning Project (2024A04J4026)

<p>The Event Horizon Telescope (EHT) has significantly advanced our ability to study black holes, achieving unprecedented spatial resolution and revealing horizon-scale structures. Notably, these observations feature a distinctive dark shadow—primarily arising from faint jet emissions—surrounded by a bright photon ring. Anticipated upgrades of the EHT promise substantial improvements in dynamic range, enabling deeper exploration of low-background regions, particularly the inner shadow defined by the lensed equatorial horizon. Our analysis shows that observations of these regions transform supermassive black holes into powerful probes for annihilating dark matter, which is expected to accumulate densely in their vicinity. By analyzing the black hole image morphology and performing electron-positron propagation calculations in realistic plasma backgrounds derived from general relativistic magnetohydrodynamic simulations, we set stringent constraints on dark matter annihilation, requiring contributions below the astrophysical emission. These constraints, derived from both current EHT observations and projections for future upgraded arrays, exclude a substantial region of previously unexplored parameter space and remain robust against astrophysical uncertainties, including black hole spin and plasma temperature variations.</p>

Denmark

Yifan Chen

Ran Ding

United States

Yuxin Liu

Yosuke Mizuno

Jing Shu

Haiyue Yu

Yanjie Zeng

Illuminating Black Hole Shadows with Dark Matter Annihilation

Dark photons have emerged as promising candidates for dark matter, and their search is a top priority in particle physics, astrophysics, and cosmology. We report the first use of a tunable niobium superconducting radio-frequency cavity for a scan search of dark photon dark matter with innovative data analysis techniques. We mechanically adjusted the resonant frequency of a cavity submerged in liquid helium at a temperature of 2 K, and scanned the dark photon mass over a frequency range of 1.37 MHz centered at 1.3 GHz. Our study leveraged the superconducting radio-frequency cavity’s remarkably high quality factors of approximately <math><msup><mn>10</mn><mn>10</mn></msup></math>, resulting in the most stringent constraints to date on a substantial portion of the exclusion parameter space on the kinetic mixing coefficient <math><mi>ε</mi></math> between dark photons and electromagnetic photons, yielding a value of <math><mi>ε</mi><mo>&lt;</mo><mn>2.2</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>16</mn></mrow></msup></math>.

Zhenxing Tang

Bo Wang

Chunlong Li

Yuting Yang

Liwen Feng

Peng Sha

Zhenghui Mi

Weimin Pan

Tianzong Zhang

Yirong Jin

Jiankui Hao

Lin Lin

Fang Wang

Huamu Xie

Senlin Huang

First Scan Search for Dark Photon Dark Matter with a Tunable Superconducting Radio-Frequency Cavity

Abstract The open N = 2 string theory is defined on the 4D space-time with the split signature (+, +, −, −). The string field theory action of the open N = 2 string theory is described by the 4D Wess–Zumino–Witten (WZW$_{4}$) model. The equation of motion of the WZW$_{4}$ model is the Yang equation, which is equivalent to the anti-self-dual Yang–Mills equation. In this paper, we study soliton-type classical solutions of the WZW$_{4}$ model in the split signature by calculating the action density of the WZW$_{4}$ model. We find that the action density of the one-soliton solutions is localized on a 3D hyperplane. This shows that there would be codimension-one-solitonic objects, or equivalently some kind of three-branes in the open N = 2 string theory. We also prove that, in the asymptotic region of the space-time, the action density of the n-soliton solutions is a “non-linear superposition” of n one-solitons. This suggests the existence of n intersecting three-branes in the N = 2 strings. Finally we make a reduction to a (1 + 2)D real space-time to calculate the energy densities of the soliton solutions. We can successfully evaluate the energy distribution for the two-soliton solutions and find that there is no singularity in the interacting region. This implies the existence of smooth intersecting codimension-one branes in the whole region. Soliton solutions in the Euclidean signature are also discussed.

Japan

Masashi Hamanaka

Shan-Chi Huang

Hiroaki Kanno

Solitons in open = 2 String Theory Kahler-Chen-Simons theory A tour through N=2 strings On soliton solutions of the anti-self-dual Yang-Mills equations from the perspective of integrable systems Soliton solutions in an integrable chiral model in 2+1 dimensions On the space-time monopole equation A review on tachyon condensation in open string field theories Soliton equations as dynamical systems on infinite dimensional Grassmann manifold

Boosted dark particles of astrophysical origin can lead to nonstandard nuclear or electron recoil signals in direct detection experiments. We conduct an investigation of the daily modulation feature of a potential future signal of this type. In particular, we perform simulations of the dark particle interactions with electrons in atoms building up the Earth on its path to the detector and provide in-depth predictions for the expected daily changes in the signal for various direct detection experiments, including XENONnT, PandaX, and LUX-ZEPLIN.

Bartosz Fornal

Pearl Sandick

Germany

Xiao Xue

Yue Zhao

Junchao Zong

Earth shielding and daily modulation from electrophilic boosted dark particles

The XENON1T collaboration reported an excess of the low-energy electron recoil events between 1 and 7 keV. We explore the possibility to explain such an anomaly by the MeV-scale dark matter (DM) heated by the interior of the Sun due to the same DM-electron interaction as in the detector. The kinetic energies of heated DM particles can reach a few keV, and can potentially account for the excess signals detected by XENON1T. We study different form factors of the DM-electron interactions, F(q) ∝ q  i  with q being the momentum exchange and i = 0, 1, 2, and find that for all these cases the inclusion of the Sun-heated DM component improves the fit to the XENON1T data. The inferred DM-electron scattering cross section (at q = αm  e  where α is the fine structure constant and m  e  is electron mass) is from ∼ 10 −38 cm2 (for i = 0) to ∼ 10 −42 cm2 (for i = 2). We also derive constraints on the DM-electron cross sections for these form factors, which are stronger than previous results with similar assumptions. We emphasize that the Sun-heated DM scenario relies on the minimum assumption on DM models, which serves as a general explanation of the XENON1T anomaly via DM-electron interaction. The spectrum of the Sun-heated DM is typically soft comparing to other boosted DM, so the small recoil events are expected to be abundant in this scenario. More sensitive direct detection experiments with lower thresholds can possibly distinguish this scenario with other boosted DM models or solar axion models.

Ming-Yang Cui

Guan-Wen Yuan

Qiang Yuan

Sun heated MeV-scale dark matter and the XENON1T electron recoil excess

With high spatial resolution, polarimetric imaging of a supermassive black hole, like <math><mrow><mi>M</mi><msup><mrow><mn>87</mn></mrow><mrow><mo>⋆</mo></mrow></msup></mrow></math> or Sgr <math><mrow><msup><mrow><mi>A</mi></mrow><mrow><mo>⋆</mo></mrow></msup></mrow></math>, by the Event Horizon Telescope can be used to probe the existence of ultralight bosonic particles, such as axions. Such particles can accumulate around a rotating black hole through the superradiance mechanism, forming an axion cloud. When linearly polarized photons are emitted from an accretion disk near the horizon, their position angles oscillate due to the birefringent effect when traveling through the axion background. In particular, the observations of supermassive black holes <math><mrow><mi>M</mi><msup><mrow><mn>87</mn></mrow><mrow><mo>⋆</mo></mrow></msup></mrow></math> (Sgr <math><mrow><msup><mrow><mi>A</mi></mrow><mrow><mo>⋆</mo></mrow></msup></mrow></math>) can probe the dimensionless axion-photon coupling <math><mi>c</mi><mo>=</mo><mn>2</mn><mi>π</mi><msub><mi>g</mi><mrow><mi>a</mi><mi>γ</mi></mrow></msub><msub><mi>f</mi><mi>a</mi></msub></math> for axions with mass around <math><mi>O</mi><mo>(</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>20</mn></mrow></msup><mo>)</mo><mtext> </mtext><mtext> </mtext><mi>eV</mi></math> [<math><mrow><mi>O</mi><mo>(</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>17</mn></mrow></msup><mo>)</mo><mtext> </mtext><mtext> </mtext><mi>eV</mi></mrow></math>] and decay constant <math><msub><mi>f</mi><mi>a</mi></msub><mo>&lt;</mo><mi>O</mi><mo>(</mo><msup><mn>10</mn><mn>16</mn></msup><mo>)</mo><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>, which is complimentary to other axion measurements.

France

Probing Axions with Event Horizon Telescope Polarimetric Measurements

We study string loop corrections to the gravity kinetic terms in type IIB com- pactifications on Calabi-Yau threefolds or their orbifold limits, in the presence of 7-branes and orientifold planes. We show that they exhibit in general a logarithmic behaviour in the large volume limit transverse to the 7-branes, induced by a localised four-dimensional Einstein-Hilbert action that appears at a lower order in the closed string sector, found in the past. Here, we compute the coefficient of the logarithmic corrections and use them to provide an explicit realisation of a mechanism for Kähler moduli stabilisation that we have proposed recently, which does not rely on non-perturbative effects and lead to de Sit- ter vacua. Our result avoids no-go theorems of perturbative stabilisation due to runaway potentials, in a way similar to the Coleman-Weinberg mechanism, and provides a counter example to one of the swampland conjectures concerning de Sitter vacua in quantum grav- ity, once string loop effects are taken into account; it thus paves the way for embedding the Standard Model of particle physics and cosmology in string theory.

Switzerland

Ignatios Antoniadis

Greece

George Leontaris

Logarithmic loop corrections, moduli stabilisation and de Sitter vacua in string theory

Stochastic gravitational waves can be produced during the preheating when out-of-equilibrium particles are produced with an anisotropic stress tensor. We discuss the case where these particles carry spin <math><mrow><mn>3</mn><mo>/</mo><mn>2</mn></mrow></math>. We compute the spectrum of the gravitational waves generated by the transverse and longitudinal components. We find a different scaling of the spectrum near the peak and the longitudinal components lead to an enhancement when compared to spin-<math><mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></mrow></math> fermions with Yukawa couplings. We note, as expected, that the corresponding typical frequency is too high for the current observation and calls for ultrahigh frequency gravitational wave detectors in the future.

Karim Benakli

Peng Cheng

Gaëtan Lafforgue-Marmet

Stochastic gravitational waves from spin-<math><mrow><mrow><mn>3</mn><mo>/</mo><mn>2</mn></mrow></mrow></math> fields

It has been observed that an automatic alignment without decoupling is predicted at tree-level in a Two-Higgs Doublet Model (2HDM) with extended supersymmetry in the gauge and Higgs sectors. Moreover, it was found that radiative corrections preserve this alignment to a very good precision. We show that it is the non-abelian global $$SU(2)_R$$ <math><mrow><mi>S</mi><mi>U</mi><msub><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow><mi>R</mi></msub></mrow></math>  R-symmetry that is at the origin of this alignment. This differs from previously considered Higgs family symmetries as it is present only in the quartic part of the Higgs potential. It can not be imposed to the quadratic part which has to be generated by $$N=1$$ <math><mrow><mi>N</mi><mo>=</mo><mn>1</mn></mrow></math>  supersymmetry breaking sectors. This absence of symmetry does not spoil alignment at the minimum of the potential. We show how the (small) misalignment induced by higher order corrections can be described as the appearance of non-singlet representations of $$SU(2)_R$$ <math><mrow><mi>S</mi><mi>U</mi><msub><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow><mi>R</mi></msub></mrow></math>  in the quartic potential.

R-symmetry for Higgs alignment without decoupling