We study classical background electric fields and the Schwinger effect in de Sitter space. We show that a constant electric field in de Sitter requires the photon to have a tachyonic mass proportional to the Hubble scale. This has physical implications for the induced Schwinger current that affect its IR behaviour. To study this, we recompute the Schwinger current in de Sitter space for charged fermions and minimally coupled scalars, imposing a physically consistent renormalization condition. We find a $\textit{finite and positive}$ Schwinger current even in the massless limit. This is in contrast to previous calculations in the literature, which found a negative IR divergence. We also obtain the first result for the Schwinger current of a non-minimally coupled scalar, including the conformally coupled case, which we find exhibits behaviour very similar to that of the fermion current. Our results may have physical implications for both magnetogenesis and inflationary dark matter production.

Spain

Mar Bastero-Gil

Portugal

Paulo B. Ferraz

António Torres Manso

Slovenia

Italy

Lorenzo Ubaldi

Roberto Vega-Morales

Schwinger current in de Sitter space * This work has been partially supported by Junta de Andalucía Projects P21-00199 and A-FQM-472-UGR20 (FEDER funds); SRA (10.13039/501100011033) and ERDF (PID2022-139466NB-C21) (R.V.M.); PID2022-140831NB-I00, funded by MICIU/AEI/10.13039/501100011033 and FEDER, UE (M.B.G., A.T.M.); by FCT CERN (10.54499/2024.00252.CERN) (M.B.G., A.T.M., P.F.); FCT Grant No. SFRH/BD/151475/2021 and 10.54499/SFRH/BD/151475/2021 (P.F.). LU is supported by the Slovenian Research Agency under research core funding No. P1-0035 and by research grants J1-60026 and J1-4389. This article is based upon work from COST Action COSMIC WISPers CA21106, supported by COST (European Cooperation in Science and Technology). R.V.M. thanks the Mainz Institute for Theoretical Physics (MITP) of the Cluster of Excellence PRISMA$^{+}$ (Project ID 390831469) for its hospitality and partial support during the completion of this work

We investigate the direct $\rm CP $ violation in the decay $ D^\pm \to \pi^\pm \pi^+ \pi^- $ incorporating the $ a_0^0(980) $ - $ f_0(980) $ mixing mechanism. The integrated mixing intensities $ \overline \xi_{fa} $ and $ \overline \xi_{af} $ are calculated using meson masses and coupling constants extracted from various theoretical models and experimental data, yielding values of appreciable magnitude. We find that when the invariant mass of the $ \pi^+\pi^- $ pair lies near the $ f_0(980) $ resonance, this isospin-breaking mechanism can enhance the $\rm CP $ asymmetry. The enhancement is particularly pronounced when the $ f_0(980) $ carries a significant $ n\bar{n} $ quark component and the $ f_0(980) $ and $ \sigma(600) $ mixing angle is approximately $ 26^\circ $ . After accounting for non-factorizable effects, we find these corrections tend to partially cancel the leading-order contributions, resulting in a suppression of the $\rm CP $ violations relative to the naive factorization predictions. It is emphasized that the $ a_0^0(980) $ - $ f_0(980) $ mixing mechanism should be taken into account in both theoretical and experimental studies of $\rm CP $ violation in $\textit{B}$ or $\textit{D}$ meson decays.

China

Shi-Ji Cao

Jing-Juan Qi

Yi-Fan Zhao

Chao Wang

Zhen-Yang Wang

Xin-Heng Guo

Direct CP violation in ${ {\boldsymbol D}^{\bf\pm }\to {\boldsymbol\pi}^{\bf\pm} {\boldsymbol\pi}^{\bf +} {\boldsymbol\pi}^{\bf -}} $ with ${{\boldsymbol a}_{\bf 0}^{\bf 0}{\bf (980)-}{\boldsymbol f}_{\bf 0}{\bf (980)}} $ mixing * Supported by the National Natural Science Foundation of China (12405115, 12105149, 11805153, 12275024), and the High-Level Scientific Research Fund of Ningbo University (GJPY2026032)

Hadron-hadron interactions, being nonperturbative in nature, play a significant role in addressing phenomenological questions in particle physics. Femtoscopy is a powerful tool in heavy-ion collision experiments, enabling the extraction of hadron-hadron interactions via momentum-correlation functions (CFs). These CFs are typically expressed as a convolution of source functions and hadron-hadron wave functions, with the latter encoding information about the interactions. However, source functions remain poorly constrained and are commonly approximated by a Gaussian form. Reconstructing source functions from experimental correlation data constitutes an 'inverse problem.' To address this, we propose a toy model based on Tikhonov regularization. Using a square-well potential with four distinct strengths, we calculate the CFs for inputs of single Gaussian source functions and mixed Gaussian source functions. The resulting CFs are then used to reconstruct the source functions via Tikhonov regularization. Our results show that the Gaussian source function can be successfully reconstructed, highlighting the potential of this approach for extracting realistic source functions from hadron pairs of interest.

Ao-Sheng Xiong

Qi-Wei Yuan

Ming-Zhu Liu

Fu-Sheng Yu

Zhi-Wei Liu

Li-Sheng Geng

Solving the inverse source problem in femtoscopy with a toy model * Supported in part by the Fundamental and Interdisciplinary Disciplines Breakthrough Plan of the Ministry of Education of China (JYB2025XDXM204) and the National Natural Science Foundation of China (W2543006, 12435007). Ming-Zhu Liu acknowledges support from the National Natural Science Foundation of China (12575086). Zhi-Wei Liu acknowledges support from the National Natural Science Foundation of China (12405133) and from the Shenzhen Science and Technology Program (ZDSYS20230626091501002). Fu-Sheng Yu and Ao-Sheng Xiong acknowledge support from the Scientific Research Innovation Capability Support Project for Young Faculty (ZYGXQNJSKYCXNLZCXM-P2) and from the Fundamental Research Funds for the Central Universities (lzujbky-2023-stlt01, lzujbky-2024-oy02, lzujbky-2025-eyt01)

We present (EvaLuator of tunnElliNg Actions), an open-source Python package designed to compute the full evolution of first-order phase transitions in the early Universe generated by particle physics models, taking into account several refinements that go beyond commonly assumed simplifications. The core of is based on a vectorized implementation of the tunnelling potential formalism, making it the first and only public code to compute finite-temperature tunnelling actions within this framework. This allows for a fast computation of the finite-temperature tunnelling action. This, in turn, enables the sampling of the full range of temperatures where two phases coexist and the use of integral expressions that track the complete evolution of the transition, providing a comprehensive picture of it. In addition, provides all the tools to compute the resulting stochastic gravitational waves spectrum, allowing for the full chain of computations – from the Lagrangian parameter inputs to the final gravitational waves spectrum – in a fast and self-contained implementation.

Czechia

Francesco Costa

Poland

Jaime Hoefken Zink

Michele Lucente

Silvia Pascoli

Salvador Rosauro-Alcaraz

ELENA: a software for fast and precise computation of first order phase transitions and gravitational waves production in particle physics models

We present the yield, average transverse momentum, and collective flow calculations of <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>K</mi><mrow><mo>*</mo><mn>0</mn></mrow></msup></math> resonances in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Au</mi><mo>+</mo><mi>Au</mi></mrow></math> collisions at <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>19.6</mn></mrow></math>, 14.5, and 7.7 GeV using the AMPT model. It is found that, due to hadronic rescattering, the decay daughters of <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>K</mi><mrow><mo>*</mo><mn>0</mn></mrow></msup></math> interact with other particles in the medium, causing the yield of reconstructable <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>K</mi><mrow><mo>*</mo><mn>0</mn></mrow></msup></math> to be significantly suppressed, especially at low transverse momentum. The model results are compared with recent experimental data from Phase-II of the Beam Energy Scan (BES-II) program at the Relativistic Heavy-Ion Collider. The string-melting version of the AMPT model successfully reproduces the measured <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mi>K</mi><mrow><mo>*</mo><mn>0</mn></mrow></msup><mo>/</mo><mi>K</mi></mrow></math> ratios at all three analyzed collision energies. Interestingly, AMPT calculations that exclude the hadronic phase nevertheless provide a reasonable description of the data, thereby challenging the conventional interpretation that hadronic rescattering is the primary mechanism responsible for suppressing the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mi>K</mi><mrow><mo>*</mo><mn>0</mn></mrow></msup><mo>/</mo><mi>K</mi></mrow></math> ratio in central heavy-ion collisions. In addition, we find that the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mi>K</mi><mrow><mo>*</mo><mn>0</mn></mrow></msup><mo>/</mo><mi>K</mi></mrow></math> ratio appears to be largely insensitive to the lifetime of the hadronic phase, whereas the average transverse momentum, <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>〈</mo><msub><mi>p</mi><mi>T</mi></msub><mo>〉</mo></mrow></math>, of the <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>K</mi><mrow><mo>*</mo><mn>0</mn></mrow></msup></math> shows a strong dependence, increasing significantly as the lifetime of the hadronic phase becomes longer. We further show that the directed flow <math xmlns="http://www.w3.org/1998/Math/MathML"><mo>(</mo><msub><mi>v</mi><mn>1</mn></msub><mo>)</mo></math> of <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>K</mi><mrow><mo>*</mo><mn>0</mn></mrow></msup></math> mesons is strongly influenced by hadronic rescattering, whereas the elliptic flow <math xmlns="http://www.w3.org/1998/Math/MathML"><mo>(</mo><msub><mi>v</mi><mn>2</mn></msub><mo>)</mo></math> exhibits only weak sensitivity to hadronic effects. These results establish <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>K</mi><mrow><mo>*</mo><mn>0</mn></mrow></msup></math> directed flow as a sensitive probe of the late-stage hadronic medium in heavy-ion collisions. These model calculations therefore provide valuable insight into the underlying physics governing the observed experimental results at RHIC.

India

Pranjal Barik

Kadambini Menduli

Aswini Kumar Sahoo

Md. Nasim

<math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>K</mi><mrow><mo>*</mo><mn>0</mn></mrow></msup></math> meson production using a multiphase transport model at RHIC BES energies

We study the partition function associated with the democratic formulation of M-theory, focusing on its global definition and quantum properties. Using a path integral representation that makes manifest the underlying cohomological structure, we analyze the coupled system of M-theory form fields ($\textit{A}$ + $\textit{A}$ ), and the background fields ($\textit{C}$ + $\textit{C}$ ), as well as their associated global transformations. We show that the resulting description is naturally captured by a Heisenberg-type group reflecting the presence of a quadratic coupling between electric and magnetic degrees of freedom. This framework provides a transparent characterization of the global structure of the theory, clarifies the role of higher-form global symmetry, and allows for a consistent definition of the partition function in terms of higher-dimensional auxiliary manifolds.

South Korea

J. Rosabal

Holographic partition function of democratic M-theory

We compute quasinormal modes of the Kazakov–Solodukhin quantum-corrected black hole using a high-precision Chebyshev spectral method. After factoring out the quasinormal mode asymptotics at the event horizon and at spatial infinity, the radial problem is reduced to a quadratic matrix pencil for the dimensionless frequency $$\Omega =M\omega $$ . We apply this framework to minimally coupled scalar perturbations, electromagnetic perturbations, a non-minimally coupled scalar field, and an axial effective source Regge–Wheeler-type gravitational sector. The latter is treated as an effective axial model, rather than as the full gravitational perturbation problem, because the Kazakov–Solodukhin spacetime is not Ricci flat. Our results reproduce the available WKB, time-domain, Mashhoon, and asymptotic-iteration benchmarks in their common regimes of validity, after accounting for the different normalisations used in the literature. The spectral method also resolves additional overtones and candidate purely imaginary overdamped roots. In several sectors, these roots exhibit a spacing scale close to $$M\kappa =1/4$$ , with occasional multiple gaps in the retained numerical sequence. In the near-extremal, but still subextremal, regime, the detected purely imaginary branches approach an approximately equally spaced surface-gravity-scaled ladder, while the oscillatory spectra remain sector dependent. Within the parameter ranges and resolutions considered here, all retained modes have $$\text {Im}\left\{ \Omega \right\} <0$$ , and no stable growing mode is detected.

United Arab Emirates

Davide Batic

Denys Dutykh

Mark Sukaiti

Quasinormal modes of the Kazakov–Solodukhin quantum-corrected black hole: a spectral analysis

We compute the spectrum of gluons emitted by a highly energetic quark inside a flowing QCD medium, focusing on the soft gluon limit at first order in the opacity expansion. Specifically, we derive the leading energy-suppressed corrections to the double differential final parton distribution, and show that they are substantial for both static and flowing matter. In particular, we demonstrate that the corrections due to the transverse flow become large even at moderate energies and flow velocities, affecting drastically both the shape and magnitude of the spectrum. We observe that the final transverse momentum of the emitted gluon tends to align along the flow direction, resulting in a nontrivial azimuthal distribution. These results can be directly implemented into the estimation of multiple observables to get a better understanding of the jet-medium interaction processes in heavy-ion collisions.

Russia

Matvey V. Kuzmin

Xoán Mayo López

Gluon radiation inside a flowing medium

In this work, we investigate the phenomenological implications of ultralight scalar dark matter (ULDM) coupled to neutrinos. We focus on a large homogeneous liquid scintillator detector, analyzing the regime where ULDM oscillations lead to time-averaged distortions in neutrino oscillation probabilities. We derive sensitivity limits on the modulation parameters <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>η</mi><msub><mi mathvariant="normal">Δ</mi><mn>21</mn></msub></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>η</mi><msub><mi mathvariant="normal">Δ</mi><mn>31</mn></msub></msub></math>, which quantify a ULDM-induced smearing effect in oscillations driven by solar (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Δ</mi><msubsup><mi>m</mi><mn>21</mn><mn>2</mn></msubsup></math>) and atmospheric (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Δ</mi><msubsup><mi>m</mi><mn>31</mn><mn>2</mn></msubsup></math>) mass-squared differences. We further demonstrate that ULDM interactions could produce a mild impact on both the determinations of the neutrino oscillation parameters and the neutrino mass-ordering sensitivity. These results showcase the benefits of a large liquid scintillator detector as a powerful probe of neutrino-ULDM interactions via neutrino oscillations.

Luis A. Delgadillo

Mexico

O.G. Miranda

Brazil

Hiroshi Nunokawa

Ultralight dark matter search in a large liquid scintillator detector

The low-lying orbital excitations of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi mathvariant="normal">Ξ</mi><mi>c</mi><mrow><mo stretchy="false">(</mo><mo>′</mo><mo stretchy="false">)</mo></mrow></msubsup></math> baryons are studied within the chiral quark model combined with the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><msub><mrow><mi>P</mi></mrow><mrow><mn>0</mn></mrow></msub></mrow><mprescripts></mprescripts><none></none><mrow><mn>3</mn></mrow></mmultiscripts></mrow></math> decay mechanism. Motivated by the LHCb observation that <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Ξ</mi><mi>c</mi></msub><mo stretchy="false">(</mo><mn>3055</mn><mo stretchy="false">)</mo></math> is a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>λ</mi></math>-mode <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1</mn><mi>D</mi></math> state with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>J</mi><mi>P</mi></msup><mo>=</mo><mn>3</mn><mo>/</mo><msup><mn>2</mn><mo>+</mo></msup></math>, we take it as a reference to constrain model parameters and perform a systematic analysis of states below 3.1 GeV. Our results provide a consistent interpretation of the observed <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Ξ</mi><mi>c</mi></msub></math> spectrum: <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Ξ</mi><mi>c</mi></msub><mo stretchy="false">(</mo><mn>2790</mn><mo stretchy="false">)</mo></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Ξ</mi><mi>c</mi></msub><mo stretchy="false">(</mo><mn>2815</mn><mo stretchy="false">)</mo></math> are well described as a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>λ</mi></math>-mode <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1</mn><mi>P</mi></math> doublet, the structures around 2.9 GeV can be interpreted as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>P</mi></math>-wave excitations with mixed <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>λ</mi><mo>/</mo><mi>ρ</mi></math> modes, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Ξ</mi><mi>c</mi></msub><mo stretchy="false">(</mo><mn>2970</mn><mo stretchy="false">)</mo></math> is consistent with a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2</mn><mi>S</mi></math> assignment. Furthermore, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Ξ</mi><mi>c</mi></msub><mo stretchy="false">(</mo><mn>3055</mn><mo stretchy="false">)</mo></math> together with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Ξ</mi><mi>c</mi></msub><mo stretchy="false">(</mo><mn>3080</mn><mo stretchy="false">)</mo></math> forms a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>λ</mi></math>-mode <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi></math>-wave doublet, while <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Ξ</mi><mi>c</mi></msub><mo stretchy="false">(</mo><mn>3123</mn><mo stretchy="false">)</mo></math> favors a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1</mn><mi>D</mi></math> assignment. These results provide a coherent picture of the low-lying <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Ξ</mi><mi>c</mi></msub></math> spectrum and call for further experimental tests.

Xiao-Huang Hu

Zhe-Tao Miu

Zi-Xuan Ma

Qi Huang

Yue Tan

Jia-Lun Ping

<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Ξ</mi><mi>c</mi></msub><mo stretchy="false">(</mo><mn>3055</mn><mo stretchy="false">)</mo></math> as a scaling point to establish the excited <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi mathvariant="normal">Ξ</mi><mi>c</mi><mrow><mo stretchy="false">(</mo><mo>′</mo><mo stretchy="false">)</mo></mrow></msubsup></math> family