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)

We constructed a four-Higgs-doublet model (4HDM) invariant under $\textit{D}$ $_{5}$ symmetry and investigated its complete neutral vacuum structure in detail. Assuming explicit CP conservation in the scalar potential, we examined whether CP symmetry can be spontaneously broken. We provided a complete list of all possible real and complex vacua, along with the constraints on the potential parameters required for each vacuum solution to exist. We also discussed the positive-definiteness conditions that the Hessian must satisfy for each vacuum to be a local minimum of the potential. The results show that, after spontaneous symmetry breaking, some complex vacua lead to spontaneous CP violation in the potential, whereas the remaining complex vacua still preserve CP conservation. Among these CP-violating complex vacua, one can be regarded as the most general form. Furthermore, we discussed the relationship between real and complex vacua.

Dong-Ping Fu

Michihisa Takeuchi

Spontaneous CP violation in the $\textit{D}$ $_{5}$-symmetric four-Higgs-doublet models * Supported by the Fundamental Research Funds for the Central Universities, the One Hundred Talent Program of Sun Yat-sen University, China, and the Guangdong Natural Science Foundation (2026A1515012641)

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 study the implications for $$B_s - \bar{B}_s$$ mixing and the neutron electric dipole moment (EDM) in a light dark matter model with sizable invisible rare meson decays to accommodate the recent possible deviations from Standard Model (SM) predictions observed in $$B^+\rightarrow K^+\nu \bar{\nu }$$ by Belle II and $$K^+\rightarrow \pi ^+\nu \bar{\nu }$$ by NA62. Given that the neutrinos in these decays escape detection, they can be replaced by other invisible final states. Based on effective operator analysis, it has been proposed that branching ratios for $$B^+\rightarrow K^+ +\text{ invisible }$$ and $$K^+\rightarrow \pi ^+ +\text{ invisible }$$ can naturally be larger than the SM predictions due to the emission of light dark matter pairs. We demonstrate that this scenario can be realized within a UV-complete two-Higgs-doublet model (2HDM) where neutral Higgs bosons mediating dark matter interactions induce significant low-energy effects especially for $$B_s-\bar{B}_s$$ mixing and neutron EDM. Within the allowed parameter space, we find non-negligible contributions to $$B_s - \bar{B}_s$$ mixing. For the neutron EDM, there is a cancellation due to the exchange of neutral spin-zero particles, but QCD renormalization group evolution will lift this cancellation which in fact is generally true for any neutral Higgs contribution. However, we demonstrate that such a cancellation does not occur for charged scalar contributions. Ultimately, the allowed CP-violating phases in the Yukawa sector can generate a neutron EDM at a level consistent with the current experimental bound.

Xuan Hong

Xiao-Gang He

Ming-Wei Li

A light DM model for large $$B \rightarrow K + \text{ invisible }$$ and $$K \rightarrow \pi + \text{ invisible }$$ decays and its implications for $$B_s-\bar{B}_s$$ mixing and neutron EDM

In asymptotically AdS spacetimes, the mathematical structure of the set of entanglement wedges reflects the algebraic structure of the underlying holographic description. For more general spacetimes, Bousso and Penington (BP) have recently proposed a generalization of entanglement wedges sharing many of the same properties as usual entanglement wedges. In this paper, we explore the hypothesis that each generalized entanglement wedge can be associated with an algebra in the (generally unknown) fundamental description (in a semiclassical limit). We postulate features of the map from entanglement wedges to algebras that provide a natural algebraic interpretation for some of the basic mathematical properties of the set of entanglement wedges. Quantitatively, we suggest a possible generalization of the Ryu-Takayanagi formula that associates the gravitational entropy of a generalized entanglement wedge with an entropic quantity for the associated algebra. Through this assignment, inclusion monotonicity and strong-subadditivity properties shown by BP for generalized entanglement wedges would follow from various inequalities satisfied by algebraic entropies. We include a detailed appendix reviewing relevant algebraic background, including a discussion of algebraic entropies and their inequalities.

Canada

Abhisek Sahu

Jeremy Heijden

Mark Raamsdonk

Rana Zibakhsh

Algebras for generalized entanglement wedges

We report a new measurement of transverse single-spin asymmetries for dijet production in collisions of polarized protons at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mrow><mn>200</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math>. Correlations between the proton spin and the transverse momenta of its partons, each perpendicular to the proton momentum direction, are probed at high <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Q</mi><mn>2</mn></msup><mo>≈</mo><mn>160</mn><mtext> </mtext><mtext> </mtext><msup><mi>GeV</mi><mn>2</mn></msup></math>. Evidence for nonzero Sivers effects is measured for the first time in dijets from proton-proton collisions, but only when the jets are sorted by their net charge, which enhances the otherwise canceling opposite-sign <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>u</mi></math>- or <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi></math>-quark contributions to separate data samples. The resulting asymmetries are compared to recent theoretical calculations. Separately, the associated Sivers observable <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">⟨</mo><msub><mi>k</mi><mi>T</mi></msub><mo stretchy="false">⟩</mo></math>, the average parton transverse momentum, is extracted using a simple kinematics approach which further enables a determination of the individual partonic contributions to the observed asymmetries.

B.E. Aboona

Czechia

J. Adam

JINR

G. Agakishiev

India

I. Aggarwal

M.M. Aggarwal

Z. Ahammed

A. Aitbayev

I. Alekseev

E. Alpatov

A.K. Alshammri

E.C. Aschenauer

A. Aparin

S. Aslam

J. Atchison

G.S. Averichev

Chile

V. Bairathi

X. Bao

P. Barik

K. Barish

S. Behera

P. Bhagat

A. Bhasin

S. Bhatta

I.G. Bordyuzhin

J.D. Brandenburg

A.V. Brandin

C. Broodo

X.Z. Cai

H. Caines

M. Calderón de la Barca Sánchez

D. Cebra

J. Ceska

I. Chakaberia

Y.S. Chang

Z. Chang

A. Chatterjee

D. Chen

J.H. Chen

L. Chen

Q. Chen

W. Chen

Z. Chen

J. Cheng

Y. Cheng

W. Christie

X. Chu

S. Corey

H.J. Crawford

G. Dale-Gau

A. Das

D. De Souza Lemos

T.G. Dedovich

Germany

I.M. Deppner

A.A. Derevschikov

A. Deshpande

A. Dhamija

A. Dimri

P. Dixit

X. Dong

J.L. Drachenberg

E. Duckworth

J.C. Dunlop

Egypt

Y.S. El-Feky

J. Engelage

G. Eppley

Japan

S. Esumi

O. Evdokimov

O. Eyser

B. Fan

Y. Fang

R. Fatemi

S. Fazio

H. Feng

Y. Feng

E. Finch

Y. Fisyak

F.A. Flor

B. Fu

C. Fu

T. Fu

T. Gao

Y. Gao

G. Garcia

F. Geurts

A. Gibson

A. Giri

K. Gopal

M. Gordon

X. Gou

D. Grosnick

A. Gu

J. Gu

A. Gupta

A. Hamed

R.J. Hamilton

J. Han

X. Han

M.D. Harasty

J.W. Harris

H. Harrison-Smith

Measurement of transverse single-spin asymmetries for dijet production in polarized proton-proton collisions at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>200</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>

Observation of baryon number violation (BNV) in laboratory experiments would constitute unambiguous evidence for physics beyond the Standard Model. We propose dedicated searches for apparent BNV in charm-baryon decays, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mi mathvariant="normal">Λ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo>+</mo></mrow></msubsup><mo stretchy="false">→</mo><msup><mrow><mi>M</mi></mrow><mrow><mo>+</mo></mrow></msup><mo>+</mo></mrow></math> missing energy (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mrow><mi>M</mi><mo>=</mo><mi>π</mi></mrow><mo>,</mo><mrow><mi>K</mi></mrow></mrow></math>), where the missing energy stems from a resonance. These channels have not been explored experimentally so far, despite the relatively clean environment potentially provided by near-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup><msubsup><mover accent="true"><mi mathvariant="normal">Λ</mi><mo stretchy="false">¯</mo></mover><mi>c</mi><mo>−</mo></msubsup></math> threshold production at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> colliders. Performing state-of-the-art Monte Carlo simulations for the proposed Super Tau-Charm Facility (STCF), we evaluate the signal efficiencies and derive projected model-independent sensitivities under the assumption of negligible background. We further interpret these sensitivities within two theoretical frameworks: a sterile-neutrino-extended low-energy effective field theory (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ν</mi><mi>LEFT</mi></math>) and R-parity-violating (RPV) supersymmetry. With an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>1</mn><mtext> </mtext><mtext> </mtext><msup><mrow><mi>ab</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math>, STCF can probe new-physics scales of several TeV in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ν</mi><mi>LEFT</mi></math> description and constrain the RPV model parameter <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>λ</mi><mn>212</mn><mo>′′</mo></msubsup><mo>/</mo><msubsup><mi>m</mi><mover accent="true"><mi>q</mi><mo stretchy="false">˜</mo></mover><mn>2</mn></msubsup></math> down to about <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>0.1</mn><mtext> </mtext><mtext> </mtext><msup><mi>TeV</mi><mrow><mo>−</mo><mn>2</mn></mrow></msup></math>. Our results demonstrate that STCF provides a highly competitive opportunity for probing BNV interactions in rare charm-baryon decays.

Zeren Simon Wang

Xin-Ru Tang

Yu Zhang

Xiaorong Zhou

Searching for apparent baryon number violation in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup></math> decays at the Super Tau-Charm Facility

A systematic way to constructing optimized interpolating operators for two-hadron systems is developed by incorporating interhadron spatial wave functions. The wave functions can be obtained from an iterative process with an appropriate initial guess. To implement these operators, a novel quark smearing technique utilizing <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>Z</mi><mn>3</mn></msub></math> noise vectors is proposed, which allows for effectively incorporating interhadron spatial wave functions at the source without using all-to-all quark propagators. Proof-of-principle application to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Ω</mi><mrow><mi>c</mi><mi>c</mi><mi>c</mi></mrow></msub><msub><mi mathvariant="normal">Ω</mi><mrow><mi>c</mi><mi>c</mi><mi>c</mi></mrow></msub></math> system using physical-point lattice configurations with a large size <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>L</mi><mi>a</mi><mo>≃</mo><mn>8.1</mn><mtext> </mtext><mtext> </mtext><mi>fm</mi></math> demonstrates that optimized operators outperform combinations of limited plane wave operators in the variational analysis, enabling clear identification of states around <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2</mn><msub><mi>m</mi><msub><mi mathvariant="normal">Ω</mi><mrow><mi>c</mi><mi>c</mi><mi>c</mi></mrow></msub></msub><mo>≃</mo><mn>9700</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></math> with the energy gap as narrow as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>∼</mo><mn>5</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></math>. A comparison on correlation functions, effective energies, and HAL QCD potentials between unoptimized operators and optimized operators is given, with a special emphasis on the effects from nearby elastic scattering states. Potential applicability of the optimized operator to various two-hadron systems and its relation to the variational method are also discussed.

Yan Lyu

Sinya Aoki

Takumi Doi

Tetsuo Hatsuda

Kotaro Murakami

Takuya Sugiura

Wave-function-based operator optimization for two-hadron systems in lattice QCD

Dark matter direct detection experiments involving electron recoils are beginning to test highly predictive, thermal-relic milestones for sub-GeV dark matter models. Due to the Lee-Weinberg bound, thermal dark matter candidates in this mass range necessarily require comparably light mediator particles to achieve a suitably large annihilation cross section. Here we present new thermal-relic milestones for sub-GeV dark matter candidates that couple to vector mediators. In these models, the mediators are massive gauge bosons of anomaly-free Abelian extensions to the Standard Model, including the dark photon, gauged <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>L</mi><mi>i</mi></msub><mo>−</mo><msub><mi>L</mi><mi>j</mi></msub><mo>,</mo><mi>B</mi><mo>−</mo><mi>L</mi></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo>−</mo><mn>3</mn><msub><mi>L</mi><mi>i</mi></msub></math> models, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi></math> is the baryon number, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>L</mi></math> is the lepton number, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>i</mi></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>j</mi></mrow></math> index the lepton families. Since the same interactions that govern cosmological production also govern electron scattering, the targets we present are firmly predictive and allow for these models to be robustly discovered or falsified. Furthermore, since the mediators we study exhaust the minimal anomaly-free U(1) extensions to the Standard Model, our results offer a complete list of predictive milestones for sub-GeV dark matter coupled to vector mediators.

United States

Xu Han

Gordan Krnjaic

New thermal-relic targets for sub-GeV dark matter direct detection