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.

China

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 match the real Higgs triplet model (RHTM) onto Higgs effective field theory (HEFT) under different parameter choices and power-counting schemes, thereby obtaining several representative HEFT formulations and clarifying their relations. We establish the primary HEFT (pHEFT) as a benchmark framework, demonstrating that alternative HEFT constructions can be systematically derived from it. A key advantage of the pHEFT construction is its parameter choice, which maintains linear relations between the UV Lagrangian parameters and squared heavy masses. By strictly employing the inverse squared heavy masses as the expansion parameters without imposing additional constraints, pHEFT preserves maximal UV information and ensures higher perturbative accuracy by avoiding the additional truncations inherent in more complex nonlinear formulations or extra constraints. Through the analysis of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>Z</mi><mn>2</mn></msub></math>-symmetric real singlet model and the two-Higgs-doublet model, we illustrate the criteria for identifying viable primary HEFT constructions in UV models with scalar extensions. Furthermore, for the first time, we derive the HEFT operators of the RHTM involving fermions.

Zizhou Ge

South Korea

Huayang Song

Xia Wan

Establishing the primary HEFT as a precision benchmark for UV-HEFT matching

We present a worldsheet action that reproduces a class of dual resonance amplitudes discussed in the literature, which generalize the Veneziano amplitude for open strings. Our proposal builds on the chiral composite linear dilaton introduced recently. We further compute higher-point extensions and closed-string analogs, which exhibit partial crossing symmetry.

CERN

Shota Komatsu

Switzerland

Pronobesh Maity

Worldsheet for Generalized Veneziano Amplitudes

The Karlsruhe Tritium Neutrino (KATRIN) experiment measures the neutrino mass from a precise measurement of the endpoint region of the kinematic tritium $$\upbeta $$ -decay spectrum by using a spectrometer combining magnetic adiabatic collimation and electrostatic filtering (MAC-E filter). For calibration purposes, KATRIN uses a monoenergetic angular-selective photoelectron source. We present an upgrade of this source, which was installed in the KATRIN beamline in February 2022. The source allows for a wide range of accessible electron energies up to 32keV and a variation of the angle with regard to the magnetic field. These features are used for precise measurements of electron scattering effects off tritium molecules in KATRIN’s gaseous tritium source, for investigations of angular-dependent backscattering for example at KATRIN’s focal-plane detector, and for studies on adiabatic transport in the main spectrometer.

Italy

Germany

S. Schneidewind

R. Sack

F. Block

United States

S. Enomoto

V. Hannen

C. Köhler

A. Lokhov

A. Marsteller

H.W. Ortjohann

R.W.J. Salomon

L. Schimpf

K. Schlösser

S. Wüstling

C. Weinheimer

A precision 32 keV angular-selective photoelectron source for calibration measurements at the KATRIN experiment

When tunneling occurs out of generic initial states, a significant fraction of probability is lost at early times, during which the dynamics is governed by excited resonance states. However, first-principles analyses based on path-integrals have only captured the leading asymptotic behavior, during which the tunneling rate is dominated by the false vacuum contribution. In this work, we discuss the behavior in the preasymptotic regime from a first-principles path-integral perspective. We demonstrate how the relevant expressions can be evaluated systematically through semiclassical methods in the recently developed steadyon picture. This approach allows one to trace the role of the relevant physical scales, making transparent the underlying assumptions and approximations, and offering a clear path to establishing a systematically improvable framework to evaluate tunneling rates nonperturbatively.

Joshua Lin

Bruno Scheihing-Hitschfeld

Spain

Thomas Steingasser

Path-integral predictions for preasymptotic quantum tunneling

We present an uncertainty-aware description of leading-power fragmentation for all-charm pentaquark states (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi></math>-wave <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">|</mo><mi>c</mi><mi>c</mi><mi>c</mi><mi>c</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">⟩</mo></math>) at hadron colliders. We construct a multimodal set of collinear fragmentation functions, PQ5Q1.1, incorporating both perturbative and nonperturbative uncertainties. Perturbative effects are estimated via missing higher-order variations, while the nonperturbative wave function is modeled through controlled modifications of its transverse-momentum structure, consistently combined within a replicalike framework. The initial-scale input for constituent charm fragmentation is refined to describe both compact multiquark and diquark-driven production mechanisms. We employ the (sym) jethad interface to study <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>NLL</mi><mo>/</mo><msup><mrow><mi>NLO</mi></mrow><mo>+</mo></msup></math> (next-to-leading logarithmic/next-to-leading order) semi-inclusive pentaquark-plus-jet production at the HL-LHC and future Future Circular Collider. The bottom sector is left to future dedicated studies due to its enhanced sensitivity to nonperturbative modeling. Our results provide a flexible framework for uncertainty-controlled predictions, bridging exotic-hadron structure, heavy-flavor fragmentation, and high-energy QCD.

Francesco Giovanni Celiberto

Multimodal fragmentation of all-heavy pentaquarks: Uncertainty-aware predictions for hadron colliders

We show that rank-ordered jet rapidity distributions provide simple probes of high-energy QCD dynamics at the LHC. Comparing the Balitsky-Fadin-Kuraev-Lipatov-based Monte Carlo (bfklex) to standard event generators based on collinear factorization and Dokshitzer–Gribov–Lipatov–Altarelli–Parisi (DGLAP) parton showers (pythia8, herwig7) in inclusive dijet topologies at 13 TeV, we find clear shape differences. While inclusive distributions can be very similar, rank-ordered spectra reveal that bfklex populates the rapidity interval more democratically, whereas DGLAP showers exhibit stronger edge enhancement and central concentration. We quantify the separation using the total-variation and one-dimensional Wasserstein distances between normalized histograms. The separation persists when applying the harder selection <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>p</mi><mrow><mi>T</mi><mo>,</mo><mi>j</mi></mrow></msub><mo>&gt;</mo><mn>60</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>H</mi><mrow><mi>T</mi><mn>2</mn></mrow></msub><mo>&gt;</mo><mn>250</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>. Rank-ordered rapidity distributions thus compress exclusive multijet information into simple histograms, offering a new handle on high-energy radiation patterns measurable with existing data.

G. Chachamis

A. Sabio Vera

Portugal

D. Vaccaro

Order statistics for multijet events

Measurements of Higgs boson Yukawa couplings to Standard Model (SM) fermions constrain radiative mass models for those species. Such models, motivated by the observed fermion mass hierarchy, act as foils for the SM tree-level mechanism: we cannot claim to have verified the standard mechanism if other possibilities also fit the data well. We construct a benchmark model which generates the top mass at tree level and the bottom, charm, tau, and tau Dirac neutrino masses at one-loop level. Current theoretical and experimental constraints on the model, including from Higgs decays, demonstrate it possesses viable regions of parameter space. We show that future improvements to measurements will not be able to rule out the model, only increase the scale of new physics required, illustrating how difficult it will be to verify the SM fermion mass generation mechanism with great precision. As a bonus, a dark matter candidate is shown to be capable of reproducing the correct relic density within the permitted parameter space.

Australia

Lucia Stockdale

Raymond R. Volkas

Higgs-Yukawa coupling constraints on a benchmark one-loop radiative mass model for the bottom, charm and tau

We consider two-point functions of light fields at finite temperature and large real frequencies in holographic theories. The thermal system is dual to a single-sided anti–de Sitter black hole. We show that the high-frequency expansion obtained from the operator product expansion receives exponentially small nonperturbative corrections, which are controlled by null geodesics bouncing off the black hole singularity in the two-sided eternal black hole geometry. We develop a bulk WKB description of these bouncing geodesics and explain how to calculate reflection coefficients at the singularity.