In the Cachazo-He-Yuan (CHY) representation, many tree-level scattering amplitudes are written as integrals localized by the scattering equations, where the CHY integrand encodes the theory and must reproduce the physical factorization pattern of Mandelstam singularities. The inverse CHY problem therefore asks for a rational integrand whose physical poles match a prescribed set of factorization channels, a task that becomes rapidly combinatorial at higher multiplicity. We present an algorithmic approach that makes the subset structure of pole data explicit by assigning each particle subset <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>A</mi></math> a generalized pole degree <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>K</mi><mo stretchy="false">(</mo><mi>A</mi><mo stretchy="false">)</mo></mrow></math>, realized as a signed internal-edge count in a colored integrand graph. Additivity under integrand multiplication and an elementary face recursion on the subset lattice imply that all higher-channel <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi><mo stretchy="false">(</mo><mi>A</mi><mo stretchy="false">)</mo></math> are linear functions of the two-particle integers <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">{</mo><mi>K</mi><mo stretchy="false">(</mo><msub><mi>s</mi><mrow><mi>i</mi><mi>j</mi></mrow></msub><mo stretchy="false">)</mo><mo stretchy="false">}</mo></math>, so the inverse step becomes a mixed-integer linear feasibility problem. The same subset lattice provides a fixed computation graph for exact constraint satisfaction: pole requirements and recursion identities are treated as hard constraints, updates are restricted to those that preserve feasibility, and whenever a proposed change would enter a fixed node its constraint residual is rerouted and redistributed through unfixed degrees of freedom so that all constraints remain satisfied throughout. After a factorial rescaling, every local propagation update is purely integral, keeping the entire procedure exact in integer arithmetic and avoiding a posteriori reconstruction from numerical evaluations. Since physical tree-level amplitudes must contain only simple factorization poles as dictated by unitarity and locality, we further organize generalized integrands by an <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>n</mi></math>-regular grading under multiplication, where degree-zero factors act as Möbius-invariant insertions admitting a decomposition into products of four-point cross ratios, which guides efficient higher-order pole reduction. We illustrate the construction at six and eight points, including pole selection and higher-order pole reduction.

China

Simeng Li

Yaobo Zhang

Inverse Cachazo-He-Yuan integrand construction from factorization channels with exact integer constraint propagation

Motivated by recent HAL QCD simulations of the <italic>&#981;N</italic> interaction in the 4 <italic>S</italic> <inf>3/2</inf> channel and its modification in the 2 <italic>S</italic> <inf>1/2</inf> channel, we develop a first-principles few-body framework that embeds these potentials into configuration-space Faddeev&#8211;Yakubovsky equations. We predict bound <math altimg='si30.svg'><mrow><msubsup><mrow /><mi>&#981;</mi><mn>4</mn></msubsup><mi mathvariant='normal'>H</mi></mrow></math>, <math altimg='si31.svg'><mrow><msubsup><mrow /><mi>&#981;</mi><mn>4</mn></msubsup><mtext>He</mtext></mrow></math>, and <math altimg='si32.svg'><mrow><msubsup><mrow /><mi>&#981;</mi><mn>5</mn></msubsup><mtext>He</mtext></mrow></math> nuclei by performing calculations for <italic>&#981;</italic>-mesic <italic>&#981;NNN</italic> and <italic>&#981;NNNN</italic> systems. Both spin-dependent and spin-independent <italic>&#981;N</italic> interactions are considered, leading to deeply and moderately bound states, respectively. The deeply bound states originate from the strong attraction in the 2 <italic>S</italic> <inf>1/2</inf> <italic>&#981;N</italic> channel. Coulomb shifts of the binding energies are evaluated. Our findings provide the binding mechanism and demonstrate the importance of short-range <italic>&#981;N</italic> attraction.

France

R. Lazauskas

United States

R.Ya. Kezerashvili

I. Filikhin

Possible existence of <math altimg='si22.svg'><msubsup><mrow /><mi>&#981;</mi><mn>3</mn></msubsup></math>H, <math altimg='si23.svg'><msubsup><mrow /><mi>&#981;</mi><mn>4</mn></msubsup></math>H, <math altimg='si23.svg'><msubsup><mrow /><mi>&#981;</mi><mn>4</mn></msubsup></math>He, and <math altimg='si24.svg'><msubsup><mrow /><mi>&#981;</mi><mn>5</mn></msubsup></math>He nuclei

We report an experimental investigation of an unexplored breakup pathway of 6Li proceeding via one-proton stripping to the unbound 5He nucleus, followed by its decay into <math altimg='si22.svg'><mrow><mi>&#945;</mi><mo linebreak='goodbreak'>+</mo><mi>n</mi></mrow></math>, in the 6Li + 112Sn reaction at <math altimg='si3.svg'><mrow><msub><mi>E</mi><mrow><mrow><mi mathvariant='normal'>b</mi></mrow><mi>e</mi><mi>a</mi><mi>m</mi></mrow></msub><mo linebreak='goodbreak'>=</mo><mn>30</mn></mrow></math> MeV. Coincident <italic>&#945;</italic>- <italic>n</italic> events were measured using an array of silicon strip telescopes in conjunction with liquid scintillator neutron detectors. Successive kinematical cuts on the reconstructed projectile-like, fragment energies and Q-values enabled a clear separation of contributions arising purely through 5He <math altimg='si6.svg'><mrow><mo>&#8594;</mo><mi>&#945;</mi><mo linebreak='goodbreak'>+</mo><mi>n</mi></mrow></math> from competing processes such as evaporation following complete and incomplete fusion. The resultant relative energy distributions exhibit a pronounced peak at 0.84 MeV, indicating sequential breakup through the first unbound resonance 5He(3/2 <math altimg='si23.svg'><msup><mrow /><mo>&#8722;</mo></msup></math>) and show good agreement with Monte-Carlo simulations. Absolute breakup cross-sections for the ( 6Li, 5He&#8239;&#8594;&#8239; <italic>&#945;n</italic>) channel are determined using the efficiency-corrected yields. In addition, angular distributions for elastic scattering and breakup cross sections are interpreted within coupled-channels (CDCC+CRC) framework. The present results provide valuable insight into transfer-induced breakup dynamics of weakly bound nuclei near the Coulomb barrier.

India

Tanya Singh

S. Santra

P.C. Rout

A. Pal

A. Baishya

H. Kumawat

T. Santhosh

M. Meher

Jyotisankar Das

Ramandeep Gandhi

Sequential breakup of 6Li via ( 6Li, 5He <math altimg='si6.svg'><mrow><mo>&#8594;</mo><mi>&#945;</mi><mo linebreak='goodbreak'>+</mo><mi>n</mi></mrow></math>) reaction

In high-energy proton-proton (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>p</mi><mi>p</mi></math>) collisions at the LHC, nonprompt charm hadrons, originating from beauty hadron decays, provide a valuable probe for beauty quark dynamics, particularly at low transverse momentum where direct beauty measurements are challenging. We employ a multiphase transport (AMPT) model of string melting version coupled with pythia8 initial conditions to study the beauty hadron and nonprompt charm hadron productions in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>p</mi><mi>p</mi></math> collisions at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math>. In this work, the beauty quark mass during the generation stage has been increased to reproduce the measured <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi><mover accent="true"><mi>b</mi><mo stretchy="false">¯</mo></mover></math> cross section, and a beauty flavor-specific coalescence parameter <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mi>r</mi></mrow><mrow><mi>B</mi><mi>M</mi></mrow><mrow><mi>b</mi></mrow></msubsup></mrow></math> is introduced to match LHCb measurements of beauty baryon-to-meson ratios. With these refinements, the AMPT model achieves a reasonable agreement with experimental data on beauty hadron yields and nonprompt charm hadron production from ALICE and LHCb. We present the transverse momentum and multiplicity dependence of nonprompt-to-prompt charm hadron ratios, providing new insights into the interplay between beauty quark production and the hadronization process. We emphasize that the multiplicity dependence of the nonprompt to prompt charm hadron productions can be useful to constrain the flavor dependences of the coalescence dynamics. This work establishes a unified framework for future studies of heavy quark transport and collective flow behavior in small collision systems.

Jialin He

Xinye Peng

Xiaoming Zhang

Liang Zheng

Studies of beauty hadron and nonprompt charm hadron production in pp collisions at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msqrt><mrow><mi>s</mi></mrow></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></mrow></math> within a transport model approach

Light <italic>s</italic>-shell hypernuclei ( <math altimg='si41.svg'><mrow><msubsup><mrow /><mstyle mathvariant='normal'><mi>&#923;</mi></mstyle><mrow><mn>3</mn><mo>,</mo><mn>4</mn></mrow></msubsup><mtext>H</mtext></mrow></math>) and their ground-state properties are crucial benchmarks in hypernuclear physics. In particular, comparing the production cross sections of <math altimg='si42.svg'><mrow><msubsup><mrow /><mstyle mathvariant='normal'><mi>&#923;</mi></mstyle><mn>3</mn></msubsup><mtext>H</mtext></mrow></math> and <math altimg='si43.svg'><mrow><msubsup><mrow /><mstyle mathvariant='normal'><mi>&#923;</mi></mstyle><mn>4</mn></msubsup><mtext>H</mtext></mrow></math> provides insights into the &#923; <italic>N</italic> interaction in different isospin configurations, which can help address recent discrepancies in the reported &#923; binding energy of hypertriton. We present the first measurement of the production cross sections for <math altimg='si42.svg'><mrow><msubsup><mrow /><mstyle mathvariant='normal'><mi>&#923;</mi></mstyle><mn>3</mn></msubsup><mtext>H</mtext></mrow></math> and <math altimg='si43.svg'><mrow><msubsup><mrow /><mstyle mathvariant='normal'><mi>&#923;</mi></mstyle><mn>4</mn></msubsup><mtext>H</mtext></mrow></math> using the in-flight <math altimg='si44.svg'><mrow><mo>(</mo><msup><mi>K</mi><mo>&#8722;</mo></msup><mo>,</mo><msup><mi>&#960;</mi><mn>0</mn></msup><mo>)</mo></mrow></math> reaction at a beam momentum of 1.0&#8239;GeV/ <italic>c</italic> with an identical experimental setup. The production cross sections in the laboratory frame, for the angular range from 0 &#8728; to 20 &#8728;, are measured to be <math altimg='si45.svg'><mrow><mn>15.0</mn><mspace width='0.33em' /><mo>&#177;</mo><mspace width='0.33em' /><mn>2.6</mn><mspace width='0.33em' /><mrow><mo>(</mo><mtext>stat.</mtext><mo>)</mo></mrow><msubsup><mspace width='0.33em' /><mrow><mo>&#8722;</mo><mn>2.8</mn></mrow><mrow><mo>+</mo><mn>2.4</mn></mrow></msubsup><mspace width='0.33em' /><mrow><mo>(</mo><mtext>syst.</mtext><mo>)</mo></mrow><mspace width='0.33em' /><mi>&#956;</mi><mtext>b</mtext></mrow></math> and <math altimg='si46.svg'><mrow><mn>49.9</mn><mspace width='0.33em' /><mo>&#177;</mo><mspace width='0.33em' /><mn>2.1</mn><mspace width='0.33em' /><mrow><mo>(</mo><mtext>stat.</mtext><mo>)</mo></mrow><msubsup><mspace width='0.33em' /><mrow><mo>&#8722;</mo><mn>8.0</mn></mrow><mrow><mo>+</mo><mn>7.8</mn></mrow></msubsup><mspace width='0.33em' /><mrow><mo>(</mo><mtext>syst.</mtext><mo>)</mo></mrow><mspace width='0.33em' /><mi>&#956;</mi><mtext>b</mtext></mrow></math> for the ground-state of <math altimg='si42.svg'><mrow><msubsup><mrow /><mstyle mathvariant='normal'><mi>&#923;</mi></mstyle><mn>3</mn></msubsup><mtext>H</mtext></mrow></math> and <math altimg='si43.svg'><mrow><msubsup><mrow /><mstyle mathvariant='normal'><mi>&#923;</mi></mstyle><mn>4</mn></msubsup><mtext>H</mtext></mrow></math>, respectively. Using the ratio of these cross sections and comparing it with theoretical calculations, we evaluate the &#923; binding energy of hypertriton, yielding a value consistent with the picture of a loosely bound system.

Japan

T. Akaishi

H. Asano

X. Chen

Italy

A. Clozza

C. Curceanu

Czechia

R. Del Grande

C.D. Han

T. Hashimoto

M. Iliescu

K. Inoue

S. Ishimoto

K. Itahashi

M. Iwasaki

Y. Ma

R. Murayama

H. Noumi

H. Ohnishi

S. Okada

H. Outa

K. Piscicchia

A. Sakaguchi

F. Sakuma

M. Sato

A. Scordo

K. Shirotori

Romania

D. Sirghi

F. Sirghi

S. Suzuki

K. Tanida

T. Toda

T. Yamaga

X. Yuan

P. Zhang

Y.P. Zhang

H. Zhang

Measurement of 3,4He( <math altimg='si40.svg'><mrow><msup><mi>K</mi><mo>&#8722;</mo></msup><mo>,</mo><msup><mi>&#960;</mi><mn>0</mn></msup><mrow><mo>)</mo></mrow><msubsup><mrow /><mstyle mathvariant='normal'><mi>&#923;</mi></mstyle><mrow><mn>3</mn><mo>,</mo><mn>4</mn></mrow></msubsup></mrow></math>H reaction cross section and evaluation of hypertriton &#923; binding energy

Event shape measurements are crucial for understanding the underlying event and multiple-parton interactions (MPIs) in high energy proton-proton (pp) collisions. In this study, the Tsallis blast-wave model with independent non-extensive parameters for mesons and baryons was applied to analyze the transverse momentum spectra of charged pions, kaons, and protons in pp collision events at $ \sqrt{s}=13 $ TeV classified by event shape estimators such as relative transverse event activity, unweighted transverse spherocity, and flattenicity. Our analysis reveals consistent trends in the kinetic freeze-out temperature and non-extensive parameter across different collision systems and event shape classes. The use of diverse event-shape observables in pp collisions has significantly expanded the accessible freeze-out parameter space, enabling a more comprehensive exploration of its boundaries. Among these event shape classifiers, flattenicity emerges as a unique observable for disentangling hard process contributions from additive MPI effects, which helps isolate collective motion effects encoded by the radial flow velocity. Through the analysis of the interplay between event-shape measurements and kinetic freeze-out properties, we gain deeper insights into mechanisms responsible for flow-like signatures in pp collisions.

Zhongbao Yin

Extracting the kinetic freeze-out properties of high energy pp collisions at the LHC with event shape classifiers * Supported by the National Key Research and Development Program of China (2024YFA1610800), the National Natural Science Foundation of China (12205259, 12147101, 12275103, 12061141008), the Fundamental Research Funds for the Central Universities, China University of Geosciences(Wuhan) with G1323523064 and the Innovation Fund of Key Laboratory of Quark and Lepton Physics QLPL2025P01

A thermal model describing hadron production in heavy-ion collisions in the few-GeV energy regime is combined with the concept of nucleon coalescence to make predictions for the production of $^{3}$H and $^{3}$He nuclei. A realistic parametrization of the freeze-out conditions is employed, which accurately reproduces the spectra of protons and pions. It also correctly predicts the deuteron yield, which agrees with experimental observations. However, the predicted yields of $^{3}$H and $^{3}$He are lower than the experimental results by approximately a factor of two. The model predictions for the spectra can be compared with future experimental data.

Poland

Zbigniew Drogosz

Wojciech Florkowski

Nikodem Witkowski

Radoslaw Ryblewski

$^{3}$H and $^{3}$He nuclei production in a combined thermal and coalescence framework for heavy-ion collisions in the few-GeV energy regime * Supported in part by the National Science Centre, Poland (NCN) (2022/47/B/ST2/01372 (W.F.) , 2018/30/E/ST2/00432 (R.R.))

We present a model-independent extraction of the $$\phi $$ – $$^{4}\textrm{He}$$ scattering length from near-threshold $$\phi $$ photoproduction on helium-4, based on LEPS Collaboration data for the coherent process $$\gamma + {}^{4}\textrm{He} \rightarrow \phi + {}^{4}\textrm{He}$$ and the Vector Meson Dominance framework. Assuming an energy-independent differential cross section, we extract the absolute value of the $$\phi -^4\!\textrm{He}$$ scattering length $$|\alpha _{\phi ^{4}\textrm{He}}| = (3.33 \pm 0.06) \times 10^{-4}~\textrm{fm}$$ from a fit at threshold $$t_{\text {thr}}$$ . This value is orders of magnitude smaller than those for $$\phi N$$ and $$\phi d$$ scattering length, indicating an inverse dependence of $$|\alpha _{VA}|$$ on the target nucleus mass. Our results provide new insight into the $$\phi $$ –nucleus interaction, supporting the notion of weak $$\phi $$ –nucleus coupling. We further explore the dependence of $$|\alpha _{VA}|$$ on the vector meson mass, the target atom mass, and the threshold energy. An approximate exponential suppression of $$|\alpha _{VA}|$$ is observed with increasing vector meson mass or target atom mass, indicating that heavier vector mesons or heavier target nuclei exhibit weaker couplings in vector meson–nucleus interactions.

Chengdong Han

Wei Kou

Rong Wang

Xurong Chen

First extraction of the $$\phi $$ - $$^{4}\textrm{He}$$ scattering length from near-threshold $$\phi $$ photoproduction on helium-4

Inclusive electron scattering at carefully chosen kinematics can isolate scattering from the high-momentum nucleons in short-range correlations (SRCs). SRCs are produced by the hard, short-distance interactions of nucleons in the nucleus, and because the two-nucleon (2N) SRCs arise from the same N-N interaction in all nuclei, the cross section in the SRC-dominated regime is identical up to an overall scaling factor. This scaling behavior has been used to identify SRC dominance and to measure the contribution of SRCs in a wide range of nuclei. We examine this scaling behavior over a range of momentum transfers using new data on 2H, 3H, and 3He, and find an expanded scaling region compared to heavy nuclei. Motivated by this improved scaling, we examine the 3H and 3He data in kinematics where three-nucleon SRCs may play an important role. The data for the largest struck nucleon momenta are consistent with isolation of scattering from three-nucleon SRCs, and suggest that the very highest momentum nucleons in 3He have a nearly isospin-independent momentum configuration.

S. Li

S.N. Santiesteban

J. Arrington

R. Cruz-Torres

L. Kurbany

D. Abrams

Saudi Arabia

S. Alsalmi

Croatia

D. Androic

K. Aniol

T. Averett

C. Ayerbe Gayoso

J. Bane

S. Barcus

J. Barrow

A. Beck

V. Bellini

H. Bhatt

D. Bhetuwal

D. Biswas

D. Bulumulla

A. Camsonne

J. Castellanos

J. Chen

J.P. Chen

D. Chrisman

M.E. Christy

C. Clarke

S. Covrig

K. Craycraft

D. Day

D. Dutta

E. Fuchey

C. Gal

F. Garibaldi

T.N. Gautam

T. Gogami

J. Gomez

P. Guèye

A. Habarakada

T.J. Hague

J.O. Hansen

F. Hauenstein

W. Henry

D.W. Higinbotham

R.J. Holt

C.E. Hyde

K. Itabashi

M. Kaneta

A. Karki

A.T. Katramatou

C.E. Keppel

M. Khachatryan

V. Khachatryan

P.M. King

Israel

I. Korover

T. Kutz

N. Lashley-Colthirst

W.B. Li

H. Liu

N. Liyanage

E. Long

Canada

J. Mammei

P. Markowitz

R.E. McClellan

F. Meddi

D. Meekins

S. Mey-Tal Beck

R. Michaels

Slovenia

Germany

M. Mihovilovič

A. Moyer

S. Nagao

V. Nelyubin

D. Nguyen

M. Nycz

M. Olson

L. Ou

V. Owen

C. Palatchi

B. Pandey

A. Papadopoulou

S. Park

S. Paul

T. Petkovic

Ukraine

R. Pomatsalyuk

S. Premathilake

V. Punjabi

R.D. Ransome

P.E. Reimer

J. Reinhold

S. Riordan

J. Roche

Puerto Rico

V.M. Rodriguez

A. Schmidt

B. Schmookler

E.P. Segarra

Armenia

A. Shahinyan

S. Širca

K. Slifer

P. Solvignon

T. Su

Inclusive studies of two- and three-nucleon short-range correlations in 3H and 3He

The Gamow shell model (GSM) framework is extended to the study of weakly bound hypernuclei. As an initial application, we investigate the neutron-rich He hyper-isotopes from <math altimg='si1.svg'><msubsup><mrow /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>6</mn></mrow></msubsup></math>He to <math altimg='si2.svg'><msubsup><mrow /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>9</mn></mrow></msubsup></math>He, accurately treating the unbound or loosely bound character of hypernuclear many-body states. The energy spectra, calculated using a phenomenological Hamiltonian with an effective <italic>YN</italic> interaction, show good agreement with available experimental data. In particular, neutron-emitting resonant states are predicted for the neutron-rich nuclei 5&#8722;8He and the hypernucleus <math altimg='si1.svg'><msubsup><mrow /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>6</mn></mrow></msubsup></math>He. Furthermore, neutron densities exhibit the long-range character of weakly bound and resonant states. This study demonstrates that GSM is a practical tool for describing the complex structure of hypernuclei, especially for those close to drip lines.

Xin Li

Gamow shell model description of neutron-rich He hyper-isotopes