We approach a systematic investigation of the one-loop mass corrections to (super-)string massive higher-spin states. While the imaginary part of the relevant amplitudes is finite, being related to the width of the decay of the states into two lower-mass states at tree level, the real part is generally IR-divergent and needs regularization and renormalization. We mostly focus on states of the first Regge trajectory in the NS-NS sector of Type-II string theories. We explicitly derive a closed-form expression for the integral over the insertion point, relying on properties of elliptic functions and lattice sums. We then regularize the IR divergent integral over the modular parameter of the torus, applying the $\textit{iε}$-prescription in string theory. As a result we compute the desired mass corrections up to level $\textit{N}$ = 10 and analyze their behavior at increasing $\textit{N}$. Finally, we speculate on the existence of mixing among lower-spin states and conjecture that the one-loop mass matrix be governed by some random matrix theory.

Italy

Massimo Bianchi

China

Maurizio Firrotta

Lorenzo Grimaldi

One-loop mass corrections and decay widths of Type II heavy string states

In the present study, we extend our previous analysis of the proton electromagnetic form factors (FFs) extracted from exclusive photon leptoproduction (EP) measurements in kinematic regions where the Bethe-Heitler (BH) process dominates the cross section by including all currently available high-precision EP data from CLAS and Hall A Collaborations. Using the same phenomenological framework, we investigate the consistency among the different datasets, determine the proton electromagnetic FFs within several fitting scenarios, and extract the corresponding charge and magnetic radii. A significant tension is found between the CLAS 2018 measurements and the remaining EP data, with the low-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">|</mo><mi>t</mi><mo stretchy="false">|</mo></math> region playing a dominant role in this tension. We systematically investigate this behavior through <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">|</mo><mi>t</mi><mo stretchy="false">|</mo></math>-cut scans and assess its impact on the extracted FFs and radii. For all analyses, the extracted proton charge radius is smaller than the Particle Data Group average and most determinations based on elastic electron-proton scattering. However, the results are consistent, within uncertainties, with the PRad measurement and muonic hydrogen spectroscopy. In contrast, the magnetic radius is found to be compatible with the current world average. These results demonstrate that BH-dominated EP measurements provide an independent and complementary approach to determine the electromagnetic structure of the proton and offer additional support for the small-radius solution of the proton charge-radius puzzle.

Iran

Muhammad Goharipour

Anoushiravan Moradi

Türkiye

K. Azizi

Implications of exclusive photon leptoproduction measurements for the proton charge-radius puzzle

We explore the properties of quark stars by combining the microscopic axion-extended Polyakov–Nambu–Jona-Lasinio model with the macroscopic framework of four-dimensional Einstein–Gauss–Bonnet (4D EGB) gravity. Specifically, axion effects are incorporated through the background phase $$\theta =a/f_a$$ in the thermodynamics of quark matter. Our results show that the inclusion of axion-induced interactions stiffens the quark-matter equation of state, thereby increasing the sound speed and the maximum mass of quark stars. The 4D EGB correction effectively weakens gravitational compression and further modifies the stellar structure, allowing for larger radii and higher maximum masses while reducing the compactness and the surface gravitational redshift. The combined effects can support quark stars above $$2\,M_\odot ,$$ with mass–radius sequences overlapping the observational regions in the indicative phenomenological comparison. These findings reveal that the interplay between axion-induced modifications of dense quark matter and 4D EGB gravity may provide a viable phenomenological framework for describing massive quark stars.

Rui Zhou

Ming-zheng-xuan Wu

Xin-ran Yang

Chong-long Xie

Min Zhou

Zhi-yang Liu

Shi-jun Mao

Guo-yun Shao

Effects of axion interactions on quark stars in 4D Einstein–Gauss–Bonnet gravity

We introduce a family of polytopes—in-in zonotopes—whose boundary structure organizes the contributions to scalar equal-time correlators in flat space computed via the in-in formalism. We provide explicit Minkowski sum and facet descriptions of these polytopes, and show that their boundaries factorize into products of graphical zonotopes and lower-dimensional in-in zonotopes, thereby mimicking the factorization structure of the correlators themselves. Evaluating their canonical forms at the origin—equivalently, calculating the volume of the dual polytope—reproduces the correlator. Finally, in a simple example, we show that the wave function decomposition of the correlator corresponds to a subdivision of the dual polytope.

United Kingdom

Ross Glew

Geometry of In-In Correlators

We present the first experimental search for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math>-naturalness tower of neutrinos using a global analysis of publicly available neutrino data. As a potential solution to the hierarchy problem, the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math>-naturalness model employs a varying Higgs mass parameter among <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math> dark sectors and encodes the required fine-tuning of the placement of the sectors in a parameter <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>r</mi></math>. We report exclusion limits on the parameter space (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>r</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math>), for normal and inverted ordering and in case the neutrino is Majorana or Dirac. In the case of a Majorana neutrino, we can rule out <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi><mo>≤</mo><msup><mn>10</mn><mn>4</mn></msup></math> sectors with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>r</mi><mo>≥</mo><mn>0.1</mn></math>. This is particularly exciting as it shows that a gauge and gravitational unification around <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>M</mi><mi>GUT</mi></msub></math>, which is a benchmark scenario of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math>-naturalness framework with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi><mo>=</mo><msup><mn>10</mn><mn>4</mn></msup></math> without fine-tuning, is ruled out by neutrino experiments.

Germany

Sofia Lonardi

France

Manuel Ettengruber

Philipp Eller

Searching for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math>-naturalness tower of neutrinos

We construct a quantum information-centered approach to describe the experimentally observed behavior of hyperon spin-pair correlations in high-energy collider experiments. The evolution of the spin density matrix of the hyperon pair is treated in the language of quantum channels, accounting both for the spin dynamics in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi mathvariant="double-struck">C</mi><mn>2</mn></msup><mo stretchy="false">⊗</mo><msup><mi mathvariant="double-struck">C</mi><mn>2</mn></msup></math> and for the pair’s angular separation <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Δ</mi><mi>R</mi></math>. We show that the experimental data are consistent with an evolution under a two-qubit depolarizing channel, from which a Lindblad master equation is derived. This provides an open quantum system picture of spin dynamics during the hadronization transition, which is not naturally captured by other quantum channels, and we discuss its microscopic origins. These results show that quantum information science can offer new insights into confinement dynamics beyond the classification of entanglement in the final particle states.

CERN

João Barata

Spain

Iván Cuntín

Enrique Rico

Bin Wu

<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Λ</mi><mover accent="true"><mi mathvariant="normal">Λ</mi><mo stretchy="false">¯</mo></mover></math> spin correlations in high-energy collisions from quantum channels: An open quantum system view of hadronization

Using forward matrix elements of local leading-twist operators, we present a determination of the isovector third Mellin moments <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">⟨</mo><msup><mrow><mi>x</mi></mrow><mrow><mn>2</mn></mrow></msup><mo stretchy="false">⟩</mo></mrow></math> of nucleon unpolarized, polarized, and transversity parton distribution functions. Two lattice QCD ensembles at the physical pion mass are used, which were generated using a tree-level Symanzik-improved gauge action and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2</mn><mo>+</mo><mn>1</mn></math> flavor tree-level improved Wilson clover fermions coupling via two-level HEX smearing. Leveraging a wide set of operators, two extraction methods for the matrix elements, and the automatic inclusion of model uncertainties via bootstrapped model averages, we extract values of the third Mellin moments. This is the first direct calculation of these observables performed at the physical pion mass.

Emilio Taggi

United States

Michael Engelhardt

Jeremy R. Green

Stefan Krieg

Stefan Meinel

John W. Negele

Andrew Pochinsky

Marcel Rodekamp

Sergey Syritsyn

Third moments of nucleon unpolarized, polarized, and transversity parton distribution functions from physical-point lattice QCD

In this work, we apply topic modeling to detect new physics in proton-proton collisions at the LHC in an unsupervised way. We investigate three new physics scenarios where fully leptonic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>t</mi><mover accent="true"><mi>t</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">→</mo><mi>b</mi><mover accent="true"><mi>b</mi><mo stretchy="false">¯</mo></mover><msup><mo>ℓ</mo><mo>+</mo></msup><msup><mo>ℓ</mo><mo>−</mo></msup><msub><mi>ν</mi><mo>ℓ</mo></msub><msub><mover accent="true"><mi>ν</mi><mo stretchy="false">¯</mo></mover><mo>ℓ</mo></msub></math> is the main source of background without relying on jet substructure variables. We demonstrate that the algorithm remains effective even in this low-particle multiplicity framework, complementing jet tagging studies, where it is typically employed. Moreover, we demonstrate that the performance of topic modeling is competitive or even better than well-known semisupervised outlier detectors, such as isolation forest and variational autoencoders, and unsupervised algorithms like Gaussian mixture models and k-means clustering with moderate and high-background pollution in almost all new physics scenarios considered.

Brazil

Alexandre Alves

Eduardo da Silva Almeida

Douglas Roberto de Matos Pimentel

Topic modeling in new physics detection

The proton’s unpolarized <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>u</mi><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo><mo>−</mo><mi>d</mi><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo></mrow></math> parton distribution function (PDF) has been studied by a number of lattice QCD groups through large momentum expansion. However, due to lattice artifacts (excited state contaminations, unphysical pion masses, and discretization effects) and less-advanced theoretical analysis (renormalizations, large-distance extrapolations, and large-log resummations), the resulting PDFs cannot be compared strictly with experimental data. By using the state-of-the-art theoretical tools and mitigating the lattice artifacts empirically, we reanalyze the available datasets in the literature and find that the new PDF for the physical-limit-extrapolated dataset (MSULat20) is consistent with global fits within <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>∼</mo><mn>1</mn><mi>σ</mi></math>, while others are broadly compatible. This provides evidence that large momentum expansion is capable of accurately predicting the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>x</mi></math> dependence of the PDFs when ideal lattice data become available.

Xiangdong Ji

Yushan Su

Proton’s Isovector Parton Distribution Function with Updated Analysis of Large-Momentum Lattice Data

The black hole horizon can induce chaotic motion of particles around the black hole. The original integrable motion of particles can transit to the chaotic motion when approaching black hole horizon. In this work, we consider the black hole background where quantum conformal anomaly correction is taken into account. We use Poincare section and Lyapunov exponent as representative probes to illustrate chaos. We investigate the effect of anomaly coefficient on the chaos of particles and for both probes, we find that quantum anomaly generally enhances the chaos of particle motions. As the chaotic orbits of particles can leave an imprint on the gravitational wave signals of the extreme mass ratio inspirals, our results pave the way to detect conformal anomaly effect in actual observations.

Yu-Sen An

Wei-Hao Zhang

Probing quantum anomaly corrections on black hole physics through chaos