Using a sample of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">(</mo><mn>10087</mn><mo>±</mo><mn>44</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mn>10</mn><mn>6</mn></msup><mtext> </mtext><mtext> </mtext><mi>J</mi><mo>/</mo><mi>ψ</mi></math> events collected with the BESIII detector, an improved measurement of the decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>η</mi><mo>′</mo></msup><mo stretchy="false">→</mo><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mi>ω</mi></math>, with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ω</mi><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup><msup><mi>π</mi><mn>0</mn></msup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>π</mi><mn>0</mn></msup><mo stretchy="false">→</mo><mi>γ</mi><mi>γ</mi></math> is performed. The branching fraction is determined to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msup><mi>η</mi><mo>′</mo></msup><mo stretchy="false">→</mo><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mi>ω</mi><mo stretchy="false">)</mo><mo>=</mo><mo stretchy="false">(</mo><mn>1.79</mn><mo>±</mo><mn>0.09</mn><mo>±</mo><mn>0.12</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>4</mn></mrow></msup></math>, where the first uncertainty is statistical and the second is systematic. This result is consistent with the previous measurement and is obtained with significantly improved precision. Furthermore, the first measurement of the transition form factor cutoff parameter for this decay is reported, with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi mathvariant="normal">Λ</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup><mo>=</mo><mo stretchy="false">(</mo><mn>2.92</mn><mo>±</mo><mn>0.83</mn><mo>±</mo><mn>0.15</mn><mo stretchy="false">)</mo><mtext> </mtext><mtext> </mtext><msup><mrow><mi>GeV</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math>. These measurements provide valuable input for understanding the internal structure of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>η</mi><mo>′</mo></msup></math> meson and testing theoretical models.

China

M. Ablikim

Russia

M.N. Achasov

Sweden

P. Adlarson

X.C. Ai

Italy

C.S. Akondi

Germany

R. Aliberti

A. Amoroso

Q. An

Y.H. An

Y. Bai

JINR

O. Bakina

H.R. Bao

X.L. Bao

M. Barbagiovanni

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

D. Cabiati

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

W. Chen

X.R. Chen

X.T. Chen

X.Y. Chen

Y.B. Chen

Y.Q. Chen

Z.K. Chen

J. 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

E. Di Fiore

X.X. Ding

Y. Ding

Y.X. Ding

Yi. Ding

J. Dong

L.Y. Dong

M.Y. Dong

X. Dong

Z.J. Dong

M.C. Du

S.X. Du

Shaoxu Du

X.L. Du

Y.Q. Du

Y.Y. Duan

Z.H. Duan

P. Egorov

G.F. Fan

J.J. Fan

Y.H. Fan

J. Fang

Jin Fang

S.S. Fang

W.X. Fang

Y.Q. Fang

Improved measurement of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>η</mi></mrow><mrow><mo>′</mo></mrow></msup><mo stretchy="false">→</mo><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><mi>ω</mi></mrow></math>

The Standard Model Effective Field Theory (SMEFT) has attracted much attention as a model-independent way for probing new physical signals. In the SMEFT framework, $$e^{-}p$$ colliders can be used to study new interactions of gauge bosons, such as neutral Triple Gauge Couplings (nTGCs). We study the signals and backgrounds of six different processes at the Future Circular Collider-hadron electron (FCC-he) and propose different event selection strategies. The expected constraints on the coefficients of the dimension-8 operators for each process, as well as the combined constraints are obtained. The results show that the sensitivity of $$e^{-}p$$ colliders to nTGCs is similar to the current Large Hadron Collider (LHC) experiments and is more competitive than that of Circular Electron Positron Collider (CEPC) experiments.

Xue-Jia Cheng

Chong-Xing Yue

Ji-Chong Yang

Si-Tong Liu

Probing neutral triple gauge couplings at $$e^{-}p$$ colliders

We study the ODE/IM correspondence for the ordinary differential equation associated with the affine Lie algebra $$ {E}_6^{(1)} $$ . The WKB expansion of the solution of the ODE is performed by the diagonalization method, and the period integrals of the WKB coefficients along the Pochhammer contour are calculated. We also compute the integrals of motion on a cylinder in two-dimensional conformal field theory with W-symmetry associated with $$ {E}_6^{(1)} $$ . Their eigenvalues on the highest-weight state are shown to agree with the period integrals up to the sixth order.

Japan

Daichi Ide

Katsushi Ito

Wataru Kono

Integrals of motion in $\textit{W E}$ 6 CFT and the ODE/IM correspondence

Using a data sample of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mn>1.0087</mn><mo>±</mo><mn>0.0044</mn><mo stretchy="false">)</mo><mo>×</mo><mrow><msup><mrow><mn>10</mn></mrow><mrow><mn>10</mn></mrow></msup></mrow></mrow></math> <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> events collected with the BESIII detector, we study the rare double Dalitz decay of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>η</mi><mo stretchy="false">→</mo><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> through the processes <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi><mo stretchy="false">→</mo><mi>γ</mi><mi>η</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi><mo stretchy="false">→</mo><mi>γ</mi><msup><mi>η</mi><mo>′</mo></msup><mo>,</mo><msup><mi>η</mi><mo>′</mo></msup><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup><mi>η</mi></math>. Clear <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>η</mi></math> signals are observed in the <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><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> invariant mass spectrum, with statistical significances of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>5.9</mn><mi>σ</mi></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>7.8</mn><mi>σ</mi></mrow></math> for the two channels, respectively. By combining both modes, we determine the branching fraction of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>η</mi><mo stretchy="false">→</mo><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">(</mo><mn>2.63</mn><mo>±</mo><mn>0.3</mn><msub><mrow><mn>4</mn></mrow><mrow><mi>stat</mi></mrow></msub><mo>±</mo><mn>0.1</mn><msub><mrow><mn>6</mn></mrow><mrow><mi>syst</mi></mrow></msub><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>5</mn></mrow></msup></mrow></math>. The result is consistent with the previous measurements within uncertainties and further constrains physics beyond the standard model.

Y. Ban

L. Fava

F. Feldbauer

G. Felici

C.Q. Feng

J.H. Feng

L. Feng

Q.X. Feng

Measurement of the double Dalitz decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>η</mi><mo stretchy="false">→</mo><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></math>

We present a search for the lepton number violating decay <math altimg='si9.svg'><mrow><msup><mstyle mathvariant='normal'><mi>&#926;</mi></mstyle><mo>&#8722;</mo></msup><mo>&#8594;</mo><msup><mstyle mathvariant='normal'><mi>&#931;</mi></mstyle><mo>+</mo></msup><msup><mi>e</mi><mo>&#8722;</mo></msup><msup><mi>e</mi><mo>&#8722;</mo></msup><mo linebreak='goodbreak'>+</mo><mi>c</mi><mo>.</mo><mi>c</mi><mo>.</mo></mrow></math> with (10087&#8239;&#177;&#8239;44)&#8239;&#215;&#8239;10 6 <italic>J</italic>/ <italic>&#968;</italic> events collected by the BESIII detector at the BEPCII collider, which provided a sample of <math altimg='si10.svg'><mrow><msup><mstyle mathvariant='normal'><mi>&#926;</mi></mstyle><mo>&#8722;</mo></msup><msup><mover accent='true'><mstyle mathvariant='normal'><mi>&#926;</mi></mstyle><mo>&#175;</mo></mover><mo>+</mo></msup></mrow></math> pairs. Employing a blind analysis strategy, no significant signal is observed above the expected background yield. The upper limit on the branching fraction is determined to be <math altimg='si11.svg'><mrow><mrow><mrow><mi mathvariant='normal'>B</mi></mrow><mi>F</mi></mrow><mrow><mo>(</mo><msup><mstyle mathvariant='normal'><mi>&#926;</mi></mstyle><mo>&#8722;</mo></msup><mo>&#8594;</mo><msup><mstyle mathvariant='normal'><mi>&#931;</mi></mstyle><mo>+</mo></msup><msup><mi>e</mi><mo>&#8722;</mo></msup><msup><mi>e</mi><mo>&#8722;</mo></msup><mo>)</mo></mrow><mo linebreak='goodbreak'>&lt;</mo><mn>2.0</mn><mo linebreak='goodbreak'>&#215;</mo><msup><mn>10</mn><mrow><mo>&#8722;</mo><mn>5</mn></mrow></msup></mrow></math> at the 90% confidence level.

Search for the lepton number violating process <math altimg='si8.svg'><mrow><msup><mstyle mathvariant='normal'><mi>&#926;</mi></mstyle><mo>&#8722;</mo></msup><mo>&#8594;</mo><msup><mstyle mathvariant='normal'><mi>&#931;</mi></mstyle><mo>+</mo></msup><msup><mi>e</mi><mo>&#8722;</mo></msup><msup><mi>e</mi><mo>&#8722;</mo></msup><mo linebreak='goodbreak'>+</mo><mi>c</mi><mo>.</mo><mi>c</mi></mrow></math>

We report on the measurements of the double-spin asymmetry from electron- 3He scattering in the threshold region of two- and three-body breakup of 3He for 4-momentum transfer values of 0.1 and 0.2 (GeV/ <italic>c</italic>) 2. The measurement was done at Jefferson Lab using a polarized 3He target with its spin aligned parallel to the beam direction. This asymmetry is sensitive to a combination of spin-dependent response functions not previously measured and may highlight differences in two body forces, meson-exchange currents and final-state interactions. The results of this measurement serve as a test of our understanding of few-body systems. When compared with calculations from plane wave impulse approximation and Faddeev calculations, we found that the latter, which use modern nuclear potentials and prescriptions for meson-exchange currents, demonstrate an overall good agreement with data.

M. Nycz

W. Armstrong

T. Averett

C. Ayerbe Gayoso

X. Bai

J. Bane

S. Barcus

J. Benesch

H. Bhatt

D. Bhetuwal

D. Biswas

A. Camsonne

G.D. Cates

J-P. Chen

J. Chen

M. Chen

C. Cotton

M.M. Dalton

Lithuania

A. Deltuva

A. Deur

B. Dhital

B. Duran

S.C. Dusa

I. Fernando

E. Fuchey

B.R. Gamage

H. Gao

D. Gaskell

T. Gautam

N. Gauthier

J. Golak

J.O. Hansen

F. Hauenstein

W. Henry

D.W. Higinbotham

Canada

G.M. Huber

C. Jantzi

S. Jia

K. Jin

M. Jones

S. Joosten

A. Karki

B. Karki

S. Katugampola

S. Kay

C. Keppel

E. King

P. King

W. Korsch

V. Kumar

R. Li

S. Li

W. Li

D. Mack

S. Malace

P. Markowitz

J. Matter

M. McCaughan

Z-E. Meziani

R. Michaels

Quasielastic <math altimg='si1.svg'><mrow><mover accent='true'><mrow><msup><mrow /><mn>3</mn></msup><mtext>He</mtext></mrow><mo>&#8594;</mo></mover><mrow><mo>(</mo><mover accent='true'><mi>e</mi><mo>&#8594;</mo></mover><mo>,</mo><msup><mi>e</mi><mo>&#8242;</mo></msup><mo>)</mo></mrow></mrow></math> asymmetry in the threshold region with a longitudinally polarized target