We present a comprehensive bottom-up analysis of lepton mass and mixing based on the non-holomorphic $A_{4}$ modular symmetry. Neutrinos are assumed to be Majorana particles, and the light neutrino masses are generated through the Weinberg operator. In this framework, we construct all phenomenologically viable models with minimal number of free parameters, with the Yukawa couplings expressed in terms of polyharmonic Maaß forms of weights $\pm4$ , $\pm2$ , and 0 at level $N=3$ . Without imposing generalized CP (gCP) symmetry, we identify 147 (six) viable models with eight real free parameters that successfully reproduce the current experimental data of the lepton sector for the normal (inverted) mass ordering. When gCP symmetry consistent with $A_{4}$ modular symmetry is included, the number of free parameters is reduced by one, yielding 47 (five) phenomenologically viable models in the normal (inverted) mass ordering. Finally, we present detailed numerical analyses of a representative model for both mass orderings to illustrate these results.

China

Xiang-Yan Gao

Cai-Chang Li

Minimal lepton models with non-holomorphic modular $\textit{A}$ $_{4}$ symmetry * Supported by Natural Science Basic Research Program of Shaanxi (2024JC-YBQN-0004) and the National Natural Science Foundation of China (12547106, 12247103)

The Schwinger effect, a non-perturbative mechanism for particle production in strong fields, plays a crucial role in understanding quantum vacuum decay and high-energy phenomena, including heavy-ion collisions (HIC). Although holographic quantum chromodynamics (QCD) models have been widely used to study this effect, most treatments assume isotropy or consider only a single type of anisotropy, neglecting the interplay between spatial and magnetic anisotropies that arise in realistic HIC scenarios. A unified framework accounting for both anisotropies is needed to accurately model particle production. We investigate the Schwinger effect in a twice anisotropic holographic QCD model incorporating both spatial and magnetic anisotropies. Using the anti-de Sitter/conformal field theory correspondence, we compute the total potential of a particle-antiparticle pair to quantify how these anisotropies influence pair production. Our results show that the magnetic field (parameterized by $c_B$ and $q_3$ ) enhances the Schwinger effect by lowering and narrowing the potential barrier, while increasing spatial anisotropy (controlled by $\nu$ ) suppresses the process by raising and widening the barrier. These findings demonstrate that magnetic and spatial anisotropies exert competing effects on particle production, emphasizing the necessity of treating both concurrently in holographic models. This work advances the theoretical description of the Schwinger effect in anisotropic environments, with implications for understanding non-equilibrium dynamics in HIC and other strongly coupled systems.

Wen-Bin Chang

Defu Hou

Schwinger effect in a twice anisotropic holographic model * Defu Hou's research is supported in part by the National Key Research and Development Program of China (2022YFA1604900). Additionally, Defu Hou receives partial support from the National Natural Science Foundation of China (NSFC) (12435009, 12275104). Wen-Bin Chang is supported by the Ph.D. Research Startup Project at Hubei Minzu University (RZ2500000857)

We investigate abelian Chern-Simons gauge theory on a strip geometry with two spatial boundaries. In the presence of boundaries, gauge invariance is broken by boundary conditions, leading to physical edge excitations. By deriving the most general local boundary conditions consistent with power counting in the sense of Symanzik, we show that the bulk equations of motion determine the boundary degrees of freedom through a broken gauge Ward identity, yielding boundary Kac-Moody current algebras with opposite central charges on the two edges. The corresponding two-dimensional boundary actions are of Tomonaga-Luttinger type and describe chiral bosons propagating in opposite directions along the two boundaries. A consistency condition, interpreted as a holographic-like bulk-boundary matching, relates the Chern-Simons coupling constant and the boundary parameters to the physical edge velocities. Within this framework, the equality and opposite sign of the two velocities in a symmetric setup follow directly from the boundary structure rather than from model-dependent assumptions about confining potentials, and the velocities are independent of the strip width. Our analysis provides a fully field-theoretic realization of bulk-boundary correspondence in Chern-Simons theory with two boundaries, with direct applications to edge physics in quantum Hall systems and related topological/hydrodynamic settings.

Erica Bertolini

Michael Doyle

Nicola Maggiore

Conor Murphy

Carlotta Piras

Edge modes in Chern-Simons theory on a strip

This study examines the spectral functions of neutral (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>π</mi><mn>0</mn></msub></math>) and charged (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>π</mi><mo>±</mo></msub></math>) pions under a uniform magnetic field using the SU(2) Nambu–Jona-Lasinio model with the Ritus method. The analysis highlights the complex interplay of magnetic field effects, thermal influences, and chiral symmetry on meson properties in extreme QCD environments. For <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>π</mi><mn>0</mn></msub></math>, whose properties are governed by the behavior of its constituent quarks, magnetic field-induced Landau levels lead to a multipeak structure in its spectral function, reflecting stable and resonance solutions that evolve with temperature, showing shifts and critical enhancements near chiral restoration. For <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>π</mi><mo>±</mo></msub></math>, cross terms that come from the asymmetry between the constituent quarks introduce Landau cuts alongside unitary cuts, indicating damping effects, with decay widths narrowing at higher temperatures, suggesting increased stability.

Jie Mei

Rui Wen

Min Zhou

Shijun Mao

Mei Huang

Spectral function for pions in a magnetic field

Using the coefficient-frame freedom of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><msup><mrow><mi>α</mi></mrow><mrow><mo>′</mo></mrow></msup><mo stretchy="false">)</mo></mrow></math> heterotic metric-dilaton effective action and incorporating it into Kaluza-Klein reduction with different reduction Ansätze and maximally symmetric internal spaces, we derive two distinct reduced five-dimensional scalar-tensor branches: a Lovelock-Horndeski-type theory and, for a special coefficient choice, an Einstein-dilaton-Gauss-Bonnet theory. We present a novel derivation of the full holographic conformal anomaly for these two reduced five-dimensional scalar-tensor theories. In the Lovelock-Horndeski case, we also construct exact asymptotically anti–de Sitter (AdS) solutions with linear-dilaton profiles and establish a holographic a-theorem. Our findings show that AdS/CFT remains sound in the presence of nonminimal scalars and higher-curvature terms, with string corrections fixing the conformal anomaly and the dual RG flow.

Tianhao Wu

Michael Stone

Holographic conformal anomaly and a-theorem in 5D scalar-tensor theories from heterotic strings

Finding a complete and yet minimal on-shell basis of operators of a given mass-dimension that are compatible with a specific set of transformation properties is the first step in any Effective Field Theory description. This step is the main bottleneck for systematic studies of leading logarithmic corrections to integer-power lattice artifacts in Symanzik Effective Field Theory targeting various local fields and lattice actions. The focus on discrete symmetry transformations in lattice field theory, especially reduced hypercubic spacetime symmetry with Euclidean signature, complicates the use of standard continuum field theory tools. Here, a new Python package is being presented that targets the typical lattice field-theorist’s use cases. While the main target lies on continuum EFTs describing 4D non-Abelian lattice gauge theories, the applicability can be extended beyond Effective Field Theories. New discrete symmetries, twisted masses, or the introduction of boosts are just a few examples of possible extensions that can be easily implemented by the user. This should allow for a wider range of theories and applications beyond the initial focus of this package. The general functionality of the package is explained along the lines of three examples: The $$\mathop {\textrm{O}}(a)$$ operator basis of the axial-vector in Wilson QCD, operator bases compatible with the symmetries of unrooted Staggered quarks as well as a pedestrian derivation of a $$B^*(\textbf{p})\pi (-\textbf{p})$$ operator with pseudo-scalar quantum numbers. Each example makes use of an increasing range of features and requires user-defined extensions show-casing the versatility of the package.

Spain

Switzerland

Nikolai Husung

opbasis: a Python package to derive minimal operator bases

This study reports on the design, simulation, construction, and testing of a full-size prototype of the multi-wire drift chamber for the CSR external-target experiment. The multi-wire drift chamber array incorporates drift cells of three different sizes: 8 $$\times $$ 8 mm $$^{\textrm{2}}$$ , 10 $$\times $$ 10 mm $$^{\textrm{2}}$$ , and 15 $$\times $$ 15 mm $$^{\textrm{2}}$$ . Simulation studies were carried out to compare their electron drift time spectra, R-T relations, and position resolution. The prototype was constructed based on the design of the multi-wire drift chamber closest to the target. Since the beam passes through the center region of the multi-wire drift chamber, the prototype features a special beam avoidance design. The design ensures that the detector is sensitive to reaction products while remaining unresponsive to heavy ion beams. The size of the prototype is 930 $$\times $$ 1660 mm $$^{\textrm{2}}$$ , comprising 960 drift cells. Testing was conducted with dedicated electronics. An energy resolution of 22% was achieved for the $$^{\textrm{55}}$$ Fe source; the track residuals were approximately 300 $$\upmu $$ m for the cosmic rays; the detection efficiency of each layer exceeds 96% for the cosmic rays.

Zhoubo He

Zhi Qin

Xiangjie Wen

Herun Yang

Xianglun Wei

Peng Ma

Rongjiang Hu

Zhijie Li

Tao Chen

Yuansheng Yang

Shichao Ren

Zhixuan He

Chengui Lu

Xiuling Zhang

Tingting Hou

Zihe Su

Canwen Liu

Shihai Wen

Haoran Yang

Junwei Yan

Zhe Cao

Zhi Deng

Jie Kong

Yuhong Yu

Zhigang Xiao

Limin Duan

A full-size multi-wire drift chamber prototype for the CSR external-target experiment

This work explores exotic signatures from confining dark sectors that may arise in the $$e^+e^-$$ collision mode at the Future Circular Collider. Assuming the Higgs boson mediates the interaction between the Standard Model and the dark sector, dark quarks can be produced in $$e^+e^-$$ collisions. The ensuing strong dynamics may lead to semi-visible jet final states, containing both visible and invisible particles. We investigate semi-visible jets with different fractions of invisible states, and enriched in leptons and photons. When the invisible component is large, selections based on kinematic features, such as the missing energy in the event, already provide good signal-to-background discrimination. For smaller invisible fractions, the reduced missing energy makes these signals more similar to Standard Model events, and we therefore employ a graph neural network jet tagger exploiting differences in jet substructure. This machine learning strategy improves sensitivity and enhances the discovery prospects of Higgs boson-induced semi-visible jets at the Future Circular Collider. Our results show that the proposed strategy can effectively probe a wide parameter space for the models considered, and a variety of signatures, constraining the Higgs boson exotic branching ratios into dark quarks at the permille-level.

Cesare Cazzaniga

Annapaola Cosa

Germany

Felix Kahlhoefer

Andrea Maria

Roberto Seidita

Emre Sitti

Probing the Higgs portal to a strongly-interacting dark sector at the FCC-ee

We apply the wavelet formalism of quantum field theory to investigate nonperturbative dynamics within the Hamiltonian framework. In particular, we employ Daubechies wavelets in momentum space, whose basis functions are labeled by resolution and translation indices, providing a natural nonperturbative truncation of both infrared and ultraviolet truncation of quantum field theories. As an application, we compute the energy spectra of a free scalar field theory and the interacting <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1</mn><mo>+</mo><mn>1</mn></math>-dimensional <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>ϕ</mi><mn>4</mn></msup></math> theory. This approach successfully reproduces the well-known strong-coupling phase transition in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>m</mi><mn>2</mn></msup><mo>&gt;</mo><mn>0</mn></math> regime. Our results indicate that with increasing resolution, the extracted critical coupling can approach toward its expected value, providing numerical evidence for the plausibility of the wavelet-based Hamiltonian formulation for nonperturbative field-theoretic calculations.

Mrinmoy Basak

Debsubhra Chakraborty

Nilmani Mathur

Raghunath Ratabole

Hamiltonian formulation of the (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>1</mn><mo>+</mo><mn>1</mn></mrow></math>)-dimensional <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>ϕ</mi><mn>4</mn></msup></math> theory in a momentum-space Daubechies wavelet basis

Future proposed lepton collider experiments will reach unprecedented levels of accuracy. To ensure the success of these experiments, and to fully exploit their wealth of data, the precision of theory calculations must reach comparable or even better levels. One bottleneck in achieving this precision target lies in the systematic, process-independent inclusion of higher-order corrections at next-to-next-to-leading order in the electroweak coupling while ensuring the correct matching with modern all-orders resummation techniques. Here, we present a solution to this problem, based on the Yennie-Frautschi-Suura theorem, which employs a local IR subtraction to remove divergences and its matching to an all-order resummation of the soft and soft-collinear logarithms.

Alan Price

Frank Krauss

Toward a fully automated differential <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mrow><mi>NNLO</mi></mrow><mrow><mi>EW</mi></mrow></msub></math> generator for lepton colliders