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)

In the present work, the strong decays of the discovered $ P_c(4380) $ , $ P_c(4440) $ , $ P_c(4457) $ and their possible isospin cousins are systematically studied via the assignment that they are meson-baryon molecular states. In detail, the strong decay constants and partial decay widths of their decay channels are calculated under the framework of QCD sum rules. The decay widths of the discovered $ P_c(4380) $ , $ P_c(4440) $ , and $ P_c(4457) $ are in good agreement with the experiments. The predictions of the decays of these three related possible isospin cousins are presented, which would shed light on their findings in experiments. In return, this may testify to the assignments of the discovered $ P_c $ states.

Xiu-Wu Wang

Xin Li

Zhi-Gang Wang

Systematic study of the strong decays of the $\textit{P}$ $\textit{c}$ states and their possible isospin cousins via the QCD sum rules * Supported by the National Natural Science Foundation of China (12575083) and the Natural Science Foundation of Hebei Province (A2024502002)

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)

The Standard Model Effective Field Theory (SMEFT) has attracted much attention as a model-independent way for probing new physical signals. In the SMEFT framework, $$e^{-}p$$ colliders can be used to study new interactions of gauge bosons, such as neutral Triple Gauge Couplings (nTGCs). We study the signals and backgrounds of six different processes at the Future Circular Collider-hadron electron (FCC-he) and propose different event selection strategies. The expected constraints on the coefficients of the dimension-8 operators for each process, as well as the combined constraints are obtained. The results show that the sensitivity of $$e^{-}p$$ colliders to nTGCs is similar to the current Large Hadron Collider (LHC) experiments and is more competitive than that of Circular Electron Positron Collider (CEPC) experiments.

Xue-Jia Cheng

Chong-Xing Yue

Ji-Chong Yang

Si-Tong Liu

Probing neutral triple gauge couplings at $$e^{-}p$$ colliders

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

The production of <math xmlns="http://www.w3.org/1998/Math/MathML"><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup></math> baryons in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Pb</mi><mo>+</mo><mi>Pb</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>5.02</mn></mrow></math> TeV is investigated within the quark recombination framework, including the energy loss of light and charm quarks inside the hot and dense medium. The model simultaneously describes the transverse momentum (<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>p</mi><mi>T</mi></msub></math>) spectra of <math xmlns="http://www.w3.org/1998/Math/MathML"><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup></math> baryons, <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo>/</mo><msup><mi>D</mi><mn>0</mn></msup></mrow></math> yield ratio, which is attributed to the dominance of the quark recombination mechanism in the quark-gluon plasma), and the second harmonic coefficient of <math xmlns="http://www.w3.org/1998/Math/MathML"><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup></math> baryons with emphasis on the effects of minijets on the azimuthal anisotropy. Furthermore, we extend the theoretical calculation to <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Pb</mi><mo>+</mo><mi>Pb</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>2.76</mn></mrow></math> TeV and make predictions for <math xmlns="http://www.w3.org/1998/Math/MathML"><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup></math> baryons and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo>/</mo><msup><mi>D</mi><mn>0</mn></msup></mrow></math> yield ratio. The simultaneous description of the yield, baryon-to-meson ratio, and azimuthal anisotropy further validates that the recombination model is an effective hadronization mechanism in heavy-ion collisions.

Jing-Zong Zhang

Hua Zheng

Lilin Zhu

Hadronization of <math xmlns="http://www.w3.org/1998/Math/MathML"><msubsup><mi mathvariant="normal">Λ</mi><mrow><mi>c</mi></mrow><mo>+</mo></msubsup></math> baryons from a recombination model in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Pb</mi><mo>+</mo><mi>Pb</mi></mrow></math> collisions at energies available at the CERN Large Hadron Collider

We study the hadron-quark mixed phase within a two-phase model for symmetric and asymmetric matter. For the quark sector we employ the (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>2</mn><mo>+</mo><mn>1</mn></mrow></math>) Polyakov-extended Nambu–Jona-Lasinio model (PNJL) with vector interactions. We investigate how the hadronic equation of state affects the phase diagram and the thermodynamic properties inside the mixed phase. The behavior of isentropic trajectories in the mixed phase depends on the fixed entropy per baryon (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi><mo>/</mo><msub><mi>ρ</mi><mi>B</mi></msub></math>), with trajectories near the critical end point (CEP) exhibiting a pronounced cooling pattern, while isentropic trajectories with low entropy per baryon undergo pronounced heating as the baryonic density increases. The adiabatic squared speed of sound displays characteristic peak and dip structures that depend on <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi><mo>/</mo><msub><mi>ρ</mi><mi>B</mi></msub></math>. The polytropic index along isentropic and isothermal trajectories, including in the vicinity of the CEP are also investigated. The effects of vector interactions and isospin asymmetry on thermodynamic observables likewise depend on the chosen <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi><mo>/</mo><msub><mi>ρ</mi><mi>B</mi></msub></math> value. Finally, we discuss the population of hyperons along isentropic trajectories and their influence on the phase diagram. The main effect of hyperons is to shift the onset of deconfinement to larger densities and decrease the density extension of the mixed phase.

Eduardo L.G. Salgado

Pedro Costa

Constança Providência

Isentropic thermodynamics across the hadron-quark mixed phase in a two-phase model with a PNJL quark description