In this study, we compute the next-to-leading-order QCD corrections to the Dirac electromagnetic form factors of the Σ hyperons within the hard-collinear factorization framework at leading power. The corresponding short-distance coefficient functions are extracted from the relevant seven-point partonic correlation functions. We find that the one-loop radiative corrections to the leading-twist hard-scattering contributions are numerically significant over a broad range of momentum transfer. Combining the perturbatively calculated hard kernels with nonperturbative Σ distribution amplitudes determined from lattice QCD, we present state-of-the-art theoretical predictions for the Σ hyperon electromagnetic form factors.

China

Bo-Xuan Shi

Hui-Xin Yu

Xue-Chen Zhao

Next-to-leading-order QCD predictions for the Σ Dirac form factors * This research is supported by the National Natural Science Foundation of China (12475097, 12535006) and the Natural Science Foundation of Tianjin (25JCZDJC01190). Xue-Chen Zhao is supported by the Postdoctoral Fellowship Program of CPSF (GZB20250794)

We assess the impact of measuring deeply virtual Compton scattering (DVCS) off protons using the planned detector at the Electron-Ion Collider in China (EicC), which is proposed as an upgrade to the High Intensity Heavy-Ion Accelerator Facility (HIAF). We develop a neural-network architecture to flexibly parameterize Compton form factors (CFFs), reliably extrapolate into unmeasured kinematic regions, and provide robust uncertainty estimates using the replica method. The framework is fitted to available worldwide DVCS data using the $ {\mathrm{Gepard}}$ software. We find a significant reduction in the uncertainties of all CFFs after incorporating pseudo-data from single and double polarization asymmetries at the EicC, with particularly strong improvements in the sea-quark region.

Yuan-Yuan Huang

Xu Cao

Taifu Feng

Croatia

Krešimir Kumerički

Yu Lu

Assessing the impact of the Electron-Ion Collider in China on deeply virtual Compton scattering * Supported by the National Key R&D Program of China (2023YFA1606703), the National Natural Science Foundation of China (12547111, 12235008, 12405105) and (PK.1.1.10.0004) co-financed by the European Union and through the European Regional Development Fund - Competitiveness and Cohesion Programme 2021-2027. TF also thanks the Hebei Natural Science Foundation (A2022201017, A2023201041) and Natural Science Foundation of Guangxi Autonomous Region (2022GXNSFDA035068)

The quark-mass dependence of the $ N^*(920) $ pole is analyzed using the $\textit{K}$-matrix method, with the $ \pi N $ scattering amplitude calculated up to the $ O(p^3) $ order in the chiral perturbation theory. As the quark mass increases, the $ N^*(920) $ pole gradually approaches the real axis in the complex $\textit{w}$-plane (where $ w=\sqrt{s} $ ). Eventually, in the $ O(p^2) $ case, it crosses the $\textit{u}$-cut on the real axis and enters the adjacent Riemann sheet when the pion mass reaches $ 526\; {\rm{MeV}} $ . At order $ O(p^3) $ , the rate at which it approaches the real axis decreases; however, it remains uncertain whether it will ultimately cross the $\textit{u}$-cut and enter the adjacent Riemann sheet. In addition, the trajectory of the $N^*(920)$ pole is in qualitative agreement with the results from the linear $\textit{σ}$ model calculation.

Xu Wang

Kai-Ge Kang

Qu-Zhi Li

Zhiguang Xiao

Han-Qing Zheng

Studies on quark-mass dependence of the $\textit{N}$ $^{*}$(920) pole from unitarized $\textit{πN}$ $\textit{χ}$PT amplitudes * Supported by China National Natural Science Foundation (12335002, 12375078) and the Fundamental Research Funds for the Central Universities

Using <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> collision data collected with the BESIII detector corresponding to an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>44.2</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math>, we measure the Born cross sections for the process <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><mo stretchy="false">→</mo><mi mathvariant="normal">Ξ</mi><mo stretchy="false">(</mo><mn>1530</mn><msup><mo stretchy="false">)</mo><mn>0</mn></msup><msup><mover accent="true"><mi mathvariant="normal">Ξ</mi><mo stretchy="false">¯</mo></mover><mn>0</mn></msup><mo>+</mo><mi mathvariant="normal">c</mi><mo>.</mo><mi mathvariant="normal">c</mi><mo>.</mo></math> at 48 center-of-mass energies between 3.51 and 4.95 GeV. The potential signal from non-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover></math> decays for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>3770</mn><mo stretchy="false">)</mo></math>, i.e., <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>ψ</mi><mo stretchy="false">(</mo><mn>3770</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi mathvariant="normal">Ξ</mi><mo stretchy="false">(</mo><mn>1530</mn><msup><mo stretchy="false">)</mo><mn>0</mn></msup><msup><mover accent="true"><mi mathvariant="normal">Ξ</mi><mo stretchy="false">¯</mo></mover><mn>0</mn></msup><mo>+</mo><mi>c</mi><mo>.</mo><mi>c</mi></mrow></math>., is investigated by fitting the dressed cross section, no obvious signal is found. The upper limit of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><mi>ψ</mi><mo stretchy="false">(</mo><mn>3770</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi mathvariant="normal">Ξ</mi><mo stretchy="false">(</mo><mn>1530</mn><msup><mo stretchy="false">)</mo><mn>0</mn></msup><msup><mover accent="true"><mi mathvariant="normal">Ξ</mi><mo stretchy="false">¯</mo></mover><mn>0</mn></msup></math>) at 90% confidence level is given.

M. Ablikim

Russia

M.N. Achasov

Sweden

P. Adlarson

X.C. Ai

Germany

R. Aliberti

Italy

A. Amoroso

Q. An

Y. Bai

JINR

O. Bakina

Y. Ban

H.R. Bao

Poland

V. Batozskaya

Mongolia

K. Begzsuren

N. Berger

M. Berlowski

M.B. 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

T.T. 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.M. Chen

T. Chen

X.R. Chen

X.T. Chen

X.Y. Chen

Y.B. Chen

Y.Q. Chen

Z.K. Chen

J.C. Cheng

L.N. Cheng

South Korea

S.K. Choi

X. Chu

G. Cibinetto

F. Cossio

United Kingdom

J. Cottee-Meldrum

H.L. Dai

J.P. Dai

X.C. Dai

A. Dbeyssi

R.E. de Boer

D. Dedovich

C.Q. Deng

Z.Y. Deng

A. Denig

I. Denisenko

M. Destefanis

F. De Mori

X.X. Ding

Y. Ding

Y.X. Ding

J. Dong

L.Y. Dong

M.Y. Dong

X. Dong

M.C. Du

S.X. Du

X.L. Du

Y.Y. Duan

Z.H. Duan

P. Egorov

G.F. Fan

J.J. Fan

Y.H. Fan

J. Fang

S.S. Fang

W.X. Fang

Y.Q. Fang

L. Fava

F. Feldbauer

G. Felici

C.Q. Feng

J.H. Feng

L. Feng

Q.X. Feng

Y.T. Feng

M. Fritsch

Cross sections measurement of <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><mo stretchy="false">→</mo><mi mathvariant="normal">Ξ</mi><mo stretchy="false">(</mo><mn>1530</mn><msup><mo stretchy="false">)</mo><mn>0</mn></msup><msup><mover accent="true"><mi mathvariant="normal">Ξ</mi><mo stretchy="false">¯</mo></mover><mn>0</mn></msup><mo>+</mo><mi mathvariant="normal">c</mi><mo>.</mo><mi mathvariant="normal">c</mi><mo>.</mo></math> and search for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>ψ</mi><mo stretchy="false">(</mo><mn>3770</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi mathvariant="normal">Ξ</mi><mo stretchy="false">(</mo><mn>1530</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mover accent="true"><mrow><mi mathvariant="normal">Ξ</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover></mrow><mrow><mn>0</mn></mrow></msup><mo>+</mo><mi mathvariant="normal">c</mi><mo>.</mo><mi mathvariant="normal">c</mi><mo>.</mo></mrow></math>

We extend an earlier lattice QCD analysis of heavy-quark current-current correlators to obtain new values for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>MS</mi><mo stretchy="true">¯</mo></mover></math> masses of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>c</mi></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi></math> quarks. The analysis uses gluon configurations from the MILC Collaboration with vacuum polarization contributions from <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>u</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>c</mi></math> quarks (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>n</mi><mi>f</mi></msub><mo>=</mo><mn>4</mn></math>), and lattice spacings down to 0.032 fm. We find that <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mover accent="true"><mi>m</mi><mo stretchy="false">¯</mo></mover><mi>b</mi></msub><mo stretchy="false">(</mo><msub><mover accent="true"><mi>m</mi><mo stretchy="false">¯</mo></mover><mi>b</mi></msub><mo>,</mo><msub><mi>n</mi><mi>f</mi></msub><mo>=</mo><mn>5</mn><mo stretchy="false">)</mo><mo>=</mo><mrow><mn>4.1923</mn><mo stretchy="false">(</mo><mn>63</mn><mo stretchy="false">)</mo></mrow><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mover accent="true"><mi>m</mi><mo stretchy="false">¯</mo></mover><mi>c</mi></msub><mo stretchy="false">(</mo><mn>3</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi><mo>,</mo><msub><mi>n</mi><mi>f</mi></msub><mo>=</mo><mn>4</mn><mo stretchy="false">)</mo><mo>=</mo><mspace linebreak="goodbreak"></mspace><mrow><mn>0.9813</mn><mo stretchy="false">(</mo><mn>34</mn><mo stretchy="false">)</mo></mrow><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mover accent="true"><mi>m</mi><mo stretchy="false">¯</mo></mover><mi>s</mi></msub><mo stretchy="false">(</mo><mn>3</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi><mo>,</mo><msub><mi>n</mi><mi>f</mi></msub><mo>=</mo><mn>4</mn><mo stretchy="false">)</mo><mo>=</mo><mrow><mn>83.39</mn><mo stretchy="false">(</mo><mn>26</mn><mo stretchy="false">)</mo></mrow><mtext> </mtext><mtext> </mtext><mi>MeV</mi></math>. These results are corrected for QED by including (quenched) QED in the simulations. They are among the most accurate values by any method to date. We give a detailed analysis of finite-lattice-spacing errors that shows why the highly improved staggered quark discretization of the quark action is particularly useful for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi></math>-quark simulations even for lattices where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>a</mi><msub><mi>m</mi><mi>b</mi></msub><mo>≈</mo><mn>1</mn></math>. We also calculate QED and isospin corrections to the (fictitious) <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>η</mi><mi>s</mi></msub></math>-meson mass, which is used to tune <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi></math>-quark masses in lattice simulations.

Brian Colquhoun

Christine T.H. Davies

Daniel Hatton

G. Peter Lepage

New high-precision <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>c</mi></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi></math> masses from pseudoscalar-pseudoscalar correlators in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>n</mi><mi>f</mi></msub><mo>=</mo><mn>4</mn></math> lattice QCD

Parton distribution functions (PDFs) are central to precision QCD phenomenology. Their Mellin moments can be computed on the lattice, but direct determinations using local operators, besides <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">⟨</mo><mi>x</mi><mo stretchy="false">⟩</mo></mrow></math>, face severe challenges from reduced hypercubic symmetry, limiting results to the lowest moments. A recently proposed method resolves these issues using gradient flow. We demonstrate the efficacy of this method by computing ratios of flavor nonsinglet pion PDF moments up to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">⟨</mo><msup><mrow><mi>x</mi></mrow><mrow><mn>5</mn></mrow></msup><mo stretchy="false">⟩</mo></mrow></math> on four lattice spacings at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>m</mi></mrow><mrow><mi>π</mi></mrow></msub><mo>≃</mo><mn>411</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></mrow></math>. The moments and reconstructed PDF agree quantitatively with recent phenomenological extractions.

Taiwan

Anthony Francis

Ireland

Patrick Fritzsch

Robert V. Harlander

Rohith Karur

Jangho Kim

Jonas T. Kohnen

Giovanni Pederiva

Dimitra A. Pefkou

Denmark

Antonio Rago

Andrea Shindler

André Walker-Loud

France

Savvas Zafeiropoulos

Gradient Flow for Parton Distribution Functions: First Application to the Pion

The correct identification of charged hadrons plays a crucial role in flavor-physics measurements. The final detector configurations at the proposed Future Circular Collider are yet to be determined and this study aims to contribute to this discussion by benchmarking the particle-identification (PID) performance of the proposed CLD and IDEA detectors using fully simulated events. At present, neither detector proposal includes dedicated PID systems, relying instead on information from the tracking subsystems. We estimate the expected level of contamination due to misidentified charged hadrons for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi></math>-flavor tagging, rare <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi><mo stretchy="false">→</mo><mi>s</mi></math> transitions, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>s</mi></math>-jet tagging. The PID information provided by silicon trackers, namely time-of-flight and energy-deposit measurements, leads to significant background suppression with high signal efficiency for the low-momentum hadrons considered for same-side <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi></math>-flavor tagging. In order to improve the contamination in rare decays where momenta are in the medium range, only good timing resolution of 30 ps and below can yield an improvement of one order of magnitude below the level achieved by kinematic criteria alone. Light-quark jet-flavor tagging requires identification of particles with very large momentum, which is not possible using only time-of-flight or energy-deposit information in silicon. Access to the number of clusters in a drift-chamber setup, as proposed for the IDEA detector, however, results in strong background suppression in every case. This suppression can be further improved in some scenarios by time-of-flight resolution of 30–50 ps or better. The PID quality generally exhibits only a small dependence on the cluster-counting efficiency. Whether dedicated PID detectors could further enhance flavor-physics sensitivity should be the subject of future study.

Anja Beck

Eluned Smith

Flavor-physics benchmarks for tracker-based particle identification at the FCC-ee

We explore the fundamental but untested possibility that the photon is a continuous spin particle (CSP) with a small but nonzero spin Casimir <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ρ</mi></math>. When <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ρ</mi><mo>≠</mo><mn>0</mn></math>, the familiar polarization modes of the photon transform nontrivially under Lorentz boosts, leading to deviations from familiar QED. Surprisingly, these deviations are strongest at low energy, but smoothly vanish in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ρ</mi><mo stretchy="false">→</mo><mn>0</mn></math> limit. In this letter, we compute corrections to the hydrogen 21-cm transition rate, which is expected to be particularly sensitive given the small hyperfine energy splitting <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ω</mi></math>. We find deviations from <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>QED</mi><mo>∝</mo><msup><mi>ρ</mi><mn>2</mn></msup><msup><mi>α</mi><mn>2</mn></msup><mo>/</mo><msup><mi>ω</mi><mn>2</mn></msup></math> at leading order, suggesting experimental constraints <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ρ</mi><mo>≲</mo><mn>1</mn><mtext> </mtext><mtext> </mtext><mi>meV</mi></math>. Building on this work, we expect that a range of other atomic, molecular, or condensed matter systems could be used to provide even more stringent tests of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ρ</mi></math> in electromagnetic interactions.

Aidan Reilly

Alessandro Russo

Philip Schuster

Natalia Toro

Hydrogen 21-cm constraints on the photon’s spin scale

We present an algorithm to include the correlation between the production and decay planes of gluons in a parton-shower simulation. The technique is based on identifying the charge currents responsible for the creation and annihilation of the vector field. It is applicable in both the hard-collinear and the soft wide-angle region. As a function of the number of particles, the algorithm scales linear in computing time and memory. We demonstrate agreement with fixed-order perturbative calculations in the relevant kinematical limits, and present a new observable that can be used to probe correlations beyond current-current interactions.

Stefan Höche

Mareen Hoppe

CERN

Daniel Reichelt

Simple algorithm for polarized parton evolution

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.