Based on a sample of $2.7\times10^{9}$ $\psi(3686)$ events collected by the BESIII detector operating at the BEPCII collider, the decay $\psi(3686)\to\gamma\chi_{cJ}, \chi_{cJ}\to\eta\eta\eta^{\prime}$ is analyzed. The decay modes $\chi_{c1}$ and $\chi_{c2}\to\eta\eta\eta^{\prime}$ are observed for the first time, and their corresponding branching fractions are determined to be ${\cal{B}}(\chi_{c1}\to\eta\eta\eta^{\prime}) = $ $ (1.40\, \pm 0.13\, (\text{stat.}) \pm 0.09\, (\text{sys.})) \times 10^{-4}$ and ${\cal{B}}(\chi_{c2}\to\eta\eta\eta^{\prime}) = (4.18\, \pm 0.84\, (\text{stat.}) \pm 0.48\, (\text{sys.})) \times 10^{-5}$ . An upper limit on the branching fraction of $\chi_{c0}\to\eta\eta\eta^{\prime}$ is set as $2.59 \times 10^{-5}$ at a 90% confidence level (CL). A partial wave analysis (PWA) of the decay $\chi_{c1}\to\eta\eta\eta^{\prime}$ is performed to search for the $1^{-+}$ exotic state $\eta_1(1855)$ . The PWA result indicates that the structure in the $\eta\eta^{\prime}$ mass spectrum is attributed to $f_0(1500)$ , while in the $\eta\eta$ mass spectrum, it is attributed to the $0^{++}$ phase space. The upper limit of ${\cal{B}}(\chi_{c1}\to\eta_{1}(1855)\eta) \cdot {\cal{B}}(\eta_{1}(1855)\to\eta\eta^{\prime}) \lt $ $ 9.79 \times 10^{-5}$ is set based on the PWA at 90% CL.

China

M. Ablikim

Russia

M.N. Achasov

Sweden

P. Adlarson

X.C. Ai

Germany

R. Aliberti

Italy

A. Amoroso

Q. An

Y. Bai

O. Bakina

Y. Ban

H.R. Bao

Poland

V. Batozskaya

Mongolia

K. Begzsuren

N. Berger

M. Berlowski

M. Bertani

D. Bettoni

F. Bianchi

E. Bianco

A. Bortone

I. Boyko

United States

R.A. Briere

A. Brueggemann

H. Cai

M.H. Cai

X. Cai

A. Calcaterra

G.F. Cao

N. Cao

Türkiye

S.A. Cetin

X.Y. Chai

J.F. Chang

G.R. Che

Y.Z. Che

C.H. Chen

Chao Chen

G. Chen

H.S. Chen

H.Y. Chen

M.L. Chen

S.J. Chen

S.L. Chen

S.M. Chen

T. Chen

X.R. Chen

X.T. Chen

X.Y. Chen

Y.B. Chen

Y.Q. Chen

Z. Chen

Z.J. Chen

Z.K. Chen

S.K. Choi

X. Chu

G. Cibinetto

F. Cossio

United Kingdom

J. Cottee-Meldrum

J.J. Cui

H.L. Dai

J.P. Dai

A. Dbeyssi

R.E. de Boer

D. Dedovich

C.Q. Deng

Z.Y. Deng

A. Denig

I. Denysenko

M. Destefanis

F. De Mori

B. Ding

X.X. Ding

Y. Ding

Y.X. Ding

J. Dong

L.Y. Dong

M.Y. Dong

X. Dong

M.C. Du

S.X. Du

Y.Y. Duan

P. Egorov

G.F. Fan

J.J. Fan

Y.H. Fan

J. Fang

S.S. Fang

W.X. Fang

Y.Q. Fang

R. Farinelli

L. Fava

F. Feldbauer

G. Felici

C.Q. Feng

J.H. Feng

L. Feng

Q.X. Feng

Search for $\textit{η}$ $_{1}$(1855) in $\textit{χ}$ $\textit{cJ}$ → $\textit{ηηη}$′ decays * Supported in part by National Key R&D Program of China (2023YFA1606000, 2023YFA1606704); National Natural Science Foundation of China (NSFC) (11635010, 11935015, 11935016, 11935018, 12025502, 12035009, 12035013, 12061131003, 12192260, 12192261, 12192262, 12192263, 12192264, 12192265, 12221005, 12225509, 12235017, 12361141819); the Chinese Academy of Sciences (CAS) Large-Scale Scientific Facility Program; CAS (YSBR-101); 100 Talents Program of CAS; The Institute of Nuclear and Particle Physics (INPAC) and Shanghai Key Laboratory for Particle Physics and Cosmology; Agencia Nacional de Investigación y Desarrollo de Chile (ANID), Chile (ANID PIA/APOYO AFB230003); German Research Foundation DFG (FOR5327); Istituto Nazionale di Fisica Nucleare, Italy; Knut and Alice Wallenberg Foundation (2021.0174, 2021.0299); Ministry of Development of Turkey (DPT2006K-120470); National Research Foundation of Korea ( NRF-2022R1A2C1092335); National Science and Technology fund of Mongolia; National Science Research and Innovation Fund (NSRF) via the Program Management Unit for Human Resources Institutional Development, Research and Innovation of Thailand ( B50G670107); Polish National Science Centre (2024/53/B/ST2/00975); Swedish Research Council (2019.04595); U. S. Department of Energy (DE-FG02-05ER41374)

We present a Physics-Informed Neural Network (PINN) framework for reconstructing the redshift-dependent Hubble parameter $$H(z)$$ within the Tsallis Holographic Dark Energy (THDE) model extended by massive neutrinos. In this approach, the modified Friedmann equation is incorporated into the neural network loss function, enabling training on Cosmic Chronometers data up to $$z \le 2$$ . The framework allows for the simultaneous estimation of the Hubble constant $$H_0$$ , the neutrino density parameter $$\Omega _\nu $$ , and the Tsallis non-extensivity index $$\delta $$ . Uncertainty quantification is performed through dropout simulations, resulting in statistically consistent $$1\sigma $$ confidence bands. Our results show that the THDE+ $$\nu $$ model, reconstructed via PINN, alleviates the statistical Hubble tension from the canonical $$\sim 5\sigma $$ level down to a range of $$0.5\sigma \le T \le 2.2\sigma $$ , depending on the redshift sampling. Additionally, we constrain the total neutrino mass to $$\Sigma m_\nu < 0.11\,\text {eV}$$ . A detailed comparison with the traditional Markov Chain Monte Carlo (MCMC) analysis demonstrates the consistency of both methods, while highlighting the competitiveness of the PINN-based THDE framework as a robust, data-driven approach for non-parametric cosmological inference within generalized thermodynamics.

Iran

Muhammad Yarahmadi

Amin Salehi

Towards a machine learning solution for hubble tension: Physics-Informed Neural Network (PINN) analysis of Tsallis Holographic Dark Energy in presence of neutrinos

We investigate and compare quantum chromodynamics (QCD) dipole cascade models, the 1D Mueller dipole model, its high energy limit, and its generalization that follows from studies of 1D systems with conformal symmetry. To address the ambiguity stemming from different definitions of the rapidity ranges in experimental measurements, we propose the entropy as the function of the logarithm of the average multiplicity, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>S</mi><mo stretchy="false">(</mo><mi>ln</mi><mo stretchy="false">⟨</mo><mi>n</mi><mo stretchy="false">⟩</mo><mo stretchy="false">)</mo></mrow></math>, as a universal observable. From the solutions of the models, we calculate both the entropy and the average charged particle multiplicity and compare to data measured in proton-proton collisions. We obtained these quantities directly from the measured multiplicity distributions and determine the model parameters via fits. We find that the generalized dipole model provides a significantly better description of the data than the 1D Mueller model.

France

Krzysztof Kutak

Hungary

Sándor Lökös

Entropy and multiplicity of hadrons in the high energy limit within dipole cascade models

We investigate constraints on couplings of Standard Model effective field theory (SMEFT) operators contributing to $\textit{Wtb}$ effective vertex at tree level. We study the one-loop level impact of these couplings on the low-energy flavour changing charged and neutral current processes and on the electroweak precision observables. We use the available data on these relevant processes to constrain the associated SMEFT/$\textit{Wtb}$ couplings. Solving the renormalisation group equations, we connect the SMEFT couplings at different scales and use the bounds at low energy to obtain the relevant bounds at the large scale Λ. Our findings indicate significantly improved constraints on the couplings compared to existing constraints on $\textit{Wtb}$ couplings by ATLAS and CMS. Additionally, we predict branching ratios for various top-quark flavour-changing neutral current processes, which exceed SM expectations by several orders of magnitude but remain within the reach of future colliders. These SMEFT couplings, or anomalous couplings of the effective $\textit{Wtb}$ vertex, can further constrain different UV-complete and simplified models that generate such interactions at the tree or loop level.

India

Subhajit Kala

Lipika Kolay

Lopamudra Mukherjee

Soumitra Nandi

Constraining anomalous $\textit{Wtb}$ and related SMEFT couplings using low-energy and electroweak precision observables

We discover a surprising relationship between exceptional effective field theories (EFTs) in de Sitter space and a notion of generalized energy conservation (GEC) of an <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>S</mi></mrow></math> matrix defined in an extended Poincaré patch of four-dimensional de Sitter. By demanding that such an <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>S</mi></mrow></math> matrix has support only when the total energies of in and out states are equal, we constrain the coupling constants in theories of self-interacting scalars living in the exceptional series of de Sitter representations. We rediscover the theories of Dirac-Born-Infeld (DBI) and special Galileon, and when increasing the conformal dimension, we find evidence for new exceptional theories where the four-point scalar self-interactions are uniquely fixed in terms of a single coupling constant. We conjecture that for each integer conformal dimension <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Δ</mi><mo>≥</mo><mn>4</mn></math>, there is at least one exceptional EFT that can be entirely fixed by GEC.

Zong-Zhe Du

David Stefanyszyn

New Exceptional Effective Field Theories in de Sitter Space from Generalized Energy Conservation

The Balitsky-Kovchegov (BK) equation offers a tractable description of the high-energy growth of gauge-theory scattering amplitudes and the nonlinear saturation effects that eventually tame it. Motivated by the upcoming Electron-Ion Collider (EIC), whose extended kinematic reach promises more decisive tests of saturation at high energies, we present a framework based on the spacelike-timelike correspondence that streamlines the computation of multi-loop corrections to the BK equation. We explicitly verify the correspondence at three loops in the large-flavor limit and predict the full non-conformal component of the three-loop BK Hamiltonian in the planar limit of a generic gauge theory, treating the numbers of fermions and scalars as free parameters.

Giacomo Brunello

Canada

Simon Caron-Huot

Giulio Crisanti

Mathieu Giroux

Sid Smith

High-energy evolution in planar QCD to three loops: the non-conformal contribution

It is shown to all orders of perturbation theory that in the effective field theory of general relativity the condition of vanishing of the vacuum energy leads to the same value of the cosmological constant viewed as a parameter of the effective Lagrangian, as obtained by demanding the consistency of the effective field theory in the Minkowski background. The resulting effective action is characterized by the cosmological constant term that vanishes exactly.

E. Epelbaum

Georgia

J. Gegelia

Ulf-G. Meißner

Vacuum energy in effective field theory of general relativity

Neural networks have emerged as a powerful paradigm for tasks in high energy physics, yet their opaque training process renders them as a black box. In contrast, the traditional cut flow method offers simplicity and interpretability but requires extensive manual tuning to identify optimal cut boundaries. To merge the strengths of both approaches, we propose the $\textit{Learnable Cut Flow}$ (LCF), a neural network that transforms the traditional cut selection into a fully differentiable, data-driven process. LCF implements two cut strategies — parallel, where observable distributions are treated independently, and sequential, where prior cuts shape subsequent ones — to flexibly determine optimal boundaries. Building on this strategy, we introduce the $\textit{Learnable Importance}$, a metric that quantifies feature importance and adjusts their contributions to the loss accordingly, offering model-driven insights unlike ad-hoc metrics. To ensure differentiability, a modified loss function replaces hard cuts with mask operations, preserving data shape throughout the training process. LCF is tested on six varied mock datasets and a realistic diboson vs. QCD dataset. Results demonstrate that LCF (1) accurately learns cut boundaries across typical feature distributions in both parallel and sequential strategies, (2) assigns higher importance to discriminative features with minimal overlap, (3) handles redundant or correlated features robustly, and (4) performs effectively in real-world scenarios. In the diboson dataset, LCF initially underperforms boosted decision trees and multilayer perceptrons when using all observables. LCF bridges the gap between traditional cut flow method and modern black-box neural networks, delivering actionable insights into the training process and feature importance. Source code and experimental data are available at .

Jing Li

Hao Sun

Learnable cut flow for high energy physics

For the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math>-point energy correlator in the collinear limit, the largest projected angle <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi></math> in the large <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math> limit can be viewed as the radius of the jet that encompasses all the collinear core particles, while contributions from soft gluons to the radius are suppressed. We relate the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math>-point energy correlator in the large <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math> limit to the moments of the fragmentation functions to a jet, and, using previous work, we compare the difference between jets initiated by heavy quarks and light quarks. This comparison demonstrates the dead-cone effect.

Lin Dai

South Korea

Chul Kim

Adam K. Leibovich

Large <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math>-point energy correlator in the collinear limit

In the Standard Model, the $$c \rightarrow u\nu {\bar{\nu }}$$ transition arises only at the one-loop level, leading to extremely suppressed branching ratios for the corresponding three-body decays of charmed hadrons. This suppression motivates the search for possible enhancements from physics beyond the Standard Model. In this work, we study the contributions to the $$c \rightarrow u\nu {\bar{\nu }}$$ transition from the $$R^{a2}_2$$ scalar leptoquark predicted in the Non-Minimal SU(5) GUT framework. We derive constraints on the model parameters using the recent BESIII results on $$D^0 \rightarrow \pi ^0\nu {\bar{\nu }}$$ and available data on $$D^0$$ – $$\bar{D}^0$$ mixing. Additional bounds from direct LHC searches for scalar leptoquarks, lepton flavor violation processes, and the LHCb upper limit on $$\mathcal {B}(D^0 \rightarrow \mu ^+ \mu ^-)$$ are also taken into account. After imposing all constraints, we show that the branching ratios of the three-body charmed hadron decays with missing energy can be enhanced up to $${{\mathcal {O}}}(10^{-6})$$ .

Gaber Faisel

Investigating three body charm hadron decays with missing energy within non-minimal SU(5)