A model for the nuclear medium modification of parton densities is presented. The approach is based on a global analysis of available deep inelastic scattering data for different nuclear targets within the rescaling model, combined with the effects of Fermi motion. The scale dependence is implemented through the DGLAP-evolved quark and gluon densities in a proton derived analytically at the leading order of QCD coupling. By fitting the rescaling parameters to experimental data on the ratio $F_2^A(x,Q^2)/F_2^{A^\prime}(x,Q^2) $ for several nuclear targets $\textit{A}$ and $\textit{A}$', we obtain predictions for nuclear parton distributions, even for unmeasured nuclei. The effects of nuclear modifications are investigated with respect to the mass number $\textit{A}$. We highlight distinct shadowing and antishadowing behaviors for gluons and quarks.

Russia

A.V. Kotikov

A.V. Lipatov

A simple model for nuclear modification of parton distribution functions * This research has been carried out at the expense of the Russian Science Foundation grant 25-22-00066, https://rscf.ru/en/project/25-22-00066/

We measured the <italic>&#946;</italic>-delayed neutron emission from 25F for the first time at the Facility for Rare Isotope Beams (FRIB). Using combined neutron and <italic>&#947;</italic>-ray detector systems of the FRIB Decay Station Initiator (FDSi), we observed <italic>&#946;</italic>-decay transitions populating neutron unbound states between 4.2 and 8 MeV in 25Ne. The experimental results led to the revision of the <italic>&#946;</italic>-decay half-life and <italic>&#946;</italic>-delayed neutron-emission probability of 25F. The <italic>&#946;</italic>-decay strength distribution of 25F extracted from the data agrees with the shell-model predictions using the USDB and SDPF-M effective interactions. This result indicates that the spherical neutron <math altimg='si1.svg'><mi>N</mi><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>16</mn></math> shell gap persists in 25F and 25Ne.

United States

J.F. Peltier

Z.Y. Xu

I. Cox

R. Grzywacz

R.S. Lubna

Japan

N. Kitamura

S. Neupane

J.M. Allmond

J. Christie

A.A. Doetsch

P. Dyszel

T. Gaballah

T.T. King

K. Kolos

S.N. Liddick

M. Madurga

T.H. Ogunbeku

B.M. Sherrill

K. Siegl

The evidence of <italic>N</italic>&#8239;=&#8239;16 shell closure and <italic>&#946;</italic>-delayed neutron emission from 25F

In a recent study, we have observed that by imposing a truncated T-duality transformation on the circular reduction of the bosonic couplings in the heterotic theory at four- and six-derivative orders, we can calculate these couplings in a particular YM gauge where the YM potential vanishes but its field strength remains non-zero. Importantly, the coupling constants are independent of the gauge choice, so these results are valid across different YM gauge choices.

Iran

Mohammad Garousi

O(9, 25) symmetry of heterotic string theory at orders α ′, α ′2

We present cross sections for the reaction <math><mrow><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><mo>→</mo><msubsup><mrow><mi>K</mi></mrow><mrow><mi>S</mi></mrow><mrow><mn>0</mn></mrow></msubsup><msubsup><mrow><mi>K</mi></mrow><mrow><mi>L</mi></mrow><mrow><mn>0</mn></mrow></msubsup></mrow></math> at center-of-mass energies ranging from 3.51 to 4.95 GeV using data samples collected in the BESIII experiment, corresponding to a total integrated luminosity of <math><mrow><mn>26.5</mn><mtext> </mtext><mtext> </mtext><msup><mrow><mi>fb</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math>. The ratio of neutral-to-charged kaon form factors at large momentum transfers (<math><mrow><mn>12</mn><mo>&lt;</mo><msup><mrow><mi>Q</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>&lt;</mo><mn>25</mn><mtext> </mtext><mtext> </mtext><msup><mrow><mi>GeV</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math>) is determined to be <math><mn>0.21</mn><mo>±</mo><mn>0.01</mn></math>, which indicates a small but significant effect of flavor-SU(3) breaking in the kaon wave function, and, consequently, excludes the possibility that flavor-SU(3) breaking is the primary reason for the strong experimental violation of the pQCD prediction <math><mrow><mo>|</mo><mi>F</mi><mo>(</mo><msup><mrow><mi>π</mi></mrow><mrow><mo>±</mo></mrow></msup><mo>)</mo><mo>|</mo><mo>/</mo><mo>|</mo><mi>F</mi><mo>(</mo><msup><mrow><mi>K</mi></mrow><mrow><mo>±</mo></mrow></msup><mo>)</mo><mo>|</mo><mo>=</mo><msubsup><mrow><mi>f</mi></mrow><mrow><mi>π</mi></mrow><mrow><mn>2</mn></mrow></msubsup><mo>/</mo><msubsup><mrow><mi>f</mi></mrow><mrow><mi>K</mi></mrow><mrow><mn>2</mn></mrow></msubsup></mrow></math>, where <math><mi>F</mi><mo>(</mo><msup><mi>π</mi><mo>±</mo></msup><mo>)</mo></math> and <math><mi>F</mi><mo>(</mo><msup><mi>K</mi><mo>±</mo></msup><mo>)</mo></math> are the form factors, and <math><msub><mi>f</mi><mi>π</mi></msub></math> and <math><msub><mi>f</mi><mi>K</mi></msub></math> are the decay constants of charged pions and kaons, respectively. We also observe a significant signal for the charmless decay <math><mrow><mi>ψ</mi><mo>(</mo><mn>3770</mn><mo>)</mo><mo>→</mo><msubsup><mrow><mi>K</mi></mrow><mrow><mi>S</mi></mrow><mrow><mn>0</mn></mrow></msubsup><msubsup><mrow><mi>K</mi></mrow><mrow><mi>L</mi></mrow><mrow><mn>0</mn></mrow></msubsup></mrow></math> for the first time. Within a <math><mn>1</mn><mi>σ</mi></math> contour of the likelihood value, the branching fraction for <math><mrow><mi>ψ</mi><mo>(</mo><mn>3770</mn><mo>)</mo><mo>→</mo><msubsup><mrow><mi>K</mi></mrow><mrow><mi>S</mi></mrow><mrow><mn>0</mn></mrow></msubsup><msubsup><mrow><mi>K</mi></mrow><mrow><mi>L</mi></mrow><mrow><mn>0</mn></mrow></msubsup></mrow></math> is determined to be <math><mrow><mi>B</mi><mo>=</mo><mo>(</mo><mn>2.6</mn><msubsup><mrow><mn>3</mn></mrow><mrow><mo>−</mo><mn>1.59</mn></mrow><mrow><mo>+</mo><mn>1.40</mn></mrow></msubsup><mo>)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>5</mn></mrow></msup></mrow></math>, and the relative phase between the continuum and <math><mi>ψ</mi><mo>(</mo><mn>3770</mn><mo>)</mo></math> amplitudes is <math><mrow><mi>ϕ</mi><mo>=</mo><mo>(</mo><mo>−</mo><mn>0.3</mn><msubsup><mrow><mn>9</mn></mrow><mrow><mo>−</mo><mn>0.10</mn></mrow><mrow><mo>+</mo><mn>0.05</mn></mrow></msubsup><mo>)</mo><mi>π</mi></mrow></math>. The branching fraction is in good agreement with the <math><mi>S</mi></math>- and <math><mi>D</mi></math>-wave charmonia mixing scheme proposed in the interpretation of the “<math><mi>ρ</mi><mi>π</mi></math> puzzle” between <math><mi>J</mi><mo>/</mo><mi>ψ</mi></math> and <math><mi>ψ</mi><mo>(</mo><mn>3686</mn><mo>)</mo></math> decays.

China

M. Ablikim

M. N. Achasov

Sweden

P. Adlarson

X. C. Ai

Germany

R. Aliberti

Italy

A. Amoroso

M. R. An

Q. An

Y. Bai

JINR

O. Bakina

I. Balossino

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

R. A. Briere

A. Brueggemann

H. Cai

X. Cai

A. Calcaterra

G. F. Cao

N. Cao

Türkiye

S. A. Cetin

J. F. Chang

T. T. Chang

W. L. Chang

G. R. Che

G. Chelkov

C. Chen

Chao Chen

G. Chen

H. S. Chen

M. L. Chen

S. J. Chen

S. L. Chen

S. M. Chen

T. Chen

X. R. Chen

X. T. Chen

Y. B. Chen

Y. Q. Chen

Z. J. Chen

South Korea

S. K. Choi

X. Chu

G. Cibinetto

S. C. Coen

F. Cossio

J. J. Cui

H. L. Dai

J. P. Dai

A. Dbeyssi

R. E. de Boer

D. Dedovich

Z. Y. Deng

A. Denig

I. Denysenko

M. Destefanis

F. De Mori

B. Ding

X. X. Ding

Y. Ding

J. Dong

L. Y. Dong

M. Y. Dong

X. Dong

M. C. Du

S. X. Du

Z. H. Duan

P. Egorov

Y. H. Fan

J. Fang

S. S. Fang

W. X. Fang

Y. Fang

Y. Q. Fang

R. Farinelli

L. Fava

F. Feldbauer

G. Felici

C. Q. Feng

J. H. Feng

United Kingdom

K. Fischer

M. Fritsch

C. D. Fu

J. L. Fu

Y. W. Fu

H. Gao

Y. N. Gao

Yang Gao

S. Garbolino

I. Garzia

Observation of Significant Flavor-SU(3) Breaking in the Kaon Wave Function at <math><mrow><mn>12</mn><mo>&lt;</mo><msup><mrow><mi>Q</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>&lt;</mo><mn>25</mn><mtext> </mtext><mtext> </mtext><msup><mrow><mi>GeV</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math> and Discovery of the Charmless Decay <math><mrow><mi>ψ</mi><mo>(</mo><mn>3770</mn><mo>)</mo><mo>→</mo><msubsup><mrow><mi>K</mi></mrow><mrow><mi>S</mi></mrow><mrow><mn>0</mn></mrow></msubsup><msubsup><mrow><mi>K</mi></mrow><mrow><mi>L</mi></mrow><mrow><mn>0</mn></mrow></msubsup></mrow></math>

The identification of jets originating from quarks and gluons, often referred to as quark/gluon tagging, plays an important role in various analyses performed at the Large Hadron Collider, as Standard Model measurements and searches for new particles decaying to quarks often rely on suppressing a large gluon-induced background. This paper describes the measurement of the efficiencies of quark/gluon taggers developed within the ATLAS Collaboration, using $\sqrt{s} = 13$ TeV proton–proton collision data with an integrated luminosity of 140 fb $^{-1}$ collected by the ATLAS experiment. Two taggers with high performances in rejecting jets from gluon over jets from quarks are studied: one tagger is based on requirements on the number of inner-detector tracks associated with the jet, and the other combines several jet substructure observables using a boosted decision tree. A method is established to determine the quark/gluon fraction in data, by using quark/gluon-enriched subsamples defined by the jet pseudorapidity. Differences in tagging efficiency between data and simulation are provided for jets with transverse momentum between 500 GeV and 2 TeV and for multiple tagger working points.

France

G. Aad

B. Abbott

K. Abeling

N.J. Abicht

S.H. Abidi

Morocco

A. Aboulhorma

Israel

H. Abramowicz

H. Abreu

Y. Abulaiti

B.S. Acharya

C. Adam Bourdarios

L. Adamczyk

S.V. Addepalli

M.J. Addison

J. Adelman

A. Adiguzel

T. Adye

A.A. Affolder

Switzerland

Y. Afik

Spain

M.N. Agaras

J. Agarwala

A. Aggarwal

Romania

C. Agheorghiesei

A. Ahmad

Azerbaijan

F. Ahmadov

Canada

W.S. Ahmed

S. Ahuja

X. Ai

G. Aielli

A. Aikot

M. Ait Tamlihat

B. Aitbenchikh

I. Aizenberg

M. Akbiyik

T.P.A. Åkesson

A.V. Akimov

D. Akiyama

N.N. Akolkar

K. Al Khoury

G.L. Alberghi

J. Albert

P. Albicocco

G.L. Albouy

S. Alderweireldt

M. Aleksa

I.N. Aleksandrov

C. Alexa

Greece

T. Alexopoulos

Performance and calibration of quark/gluon-jet taggers using 140 fb$^{−1}$ of $\textit{pp}$ collisions at ${{\sqrt{\boldsymbol s}\bf = 13}}$ TeV with the ATLAS detector * We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWFW and FWF, Austria; ANAS, Azerbaijan; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; ANID, Chile; CAS, MOST and NSFC, China; Minciencias, Colombia; MEYS CR, Czech Republic; DNRF and DNSRC, Denmark; IN2P3-CNRS and CEA-DRF/IRFU, France; SRNSFG, Georgia; BMBF, HGF and MPG, Germany; GSRI, Greece; RGC and Hong Kong SAR, China; ISF and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; NWO, Netherlands; RCN, Norway; MEiN, Poland; FCT, Portugal; MNE/IFA, Romania; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZŠ, Slovenia; DSI/NRF, South Africa; MICINN, Spain; SRC and Wallenberg Foundation, Sweden; SERI, SNSF and Cantons of Bern and Geneva, Switzerland; MOST, Taipei; TENMAK, Türkiye; STFC, United Kingdom; DOE and NSF, United States of America. In addition, individual groups and members have received support from BCKDF, CANARIE, CRC and DRAC, Canada; PRIMUS 21/SCI/017 and UNCE SCI/013, Czech Republic; COST, ERC, ERDF, Horizon 2020, ICSC-Next Generation EU and Marie Skłodowska-Curie Actions, European Union; Investissements d'Avenir Labex, Investissements d'Avenir Idex and ANR, France; DFG and AvH Foundation, Germany; Herakleitos, Thales and Aristeia programmes co-financed by EU-ESF and the Greek NSRF, Greece; BSF-NSF and MINERVA, Israel; Norwegian Financial Mechanism 2014-2021, Norway; NCN and NAWA, Poland; La Caixa Banking Foundation, CERCA Programme Generalitat de Catalunya and PROMETEO and GenT Programmes Generalitat Valenciana, Spain; Göran Gustafssons Stiftelse, Sweden; The Royal Society and Leverhulme Trust, United Kingdom.