We investigate the processes $\textit{e}$ $\textit{e}$ → $\textit{η}$ + $\textit{γ}$ and $\textit{e}$ $\textit{e}$ → $\textit{χ}$ + $\textit{γ}$ at B factories within the NRQCD factorization framework, computing the corresponding helicity amplitudes through $$ \mathcal{O}\left({\alpha}_s^2\right) $$ . The short-distance coefficients are obtained as series expansions in $$ r=\frac{4{m}_c^2}{s} $$ around $\textit{r}$ = 0, 1/3, 2/3, 1, using the method of differential equations. By combining the expansions from all four points, we construct composite asymptotic expressions that reproduce the exact results accurately over the full range 0 ≤ $\textit{r}$ ≤ 1, with relative errors below 0.1% over most of the domain and remaining under 1% elsewhere. Analytic expressions for the leading and next-to-leading logarithmic terms are extracted in the limit $\textit{r}$ → 0. Using these results, we compute the unpolarized cross sections and observe that the perturbative corrections are small for $\textit{χ}$ + $\textit{γ}$, moderate for $\textit{χ}$ + $\textit{γ}$, and substantial for $\textit{η}$ + $\textit{γ}$ and $\textit{χ}$ + $\textit{γ}$. Theoretical prediction for $\textit{χ}$ + $\textit{γ}$ is consistent with the Belle measurement within 2$\textit{σ}$, showing good agreement between theory and experiment. We also predict the angular distribution parameters $$ {\alpha}_{\theta}^H $$ , which are insensitive to NRQCD matrix elements and exhibit small theoretical uncertainties. These parameters further display good stability across different perturbative orders. With the high luminosity anticipated at Belle 2, future experimental measurements will thus provide a clear test of NRQCD factorization.

China

Cong Li

Wen-Long Sang

Hong-Fei Zhang

The next-to-next-to-leading-order QCD corrections to $\textit{e}$ + $\textit{e}$ $\textit{−}$ $\textit{→ η}$ $\textit{c}$ $\textit{/χ}$ $\textit{cJ}$ + $\textit{γ}$ at B factories

We search for 15 rare decays of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi></math> mesons to hadrons accompanied by an electron-positron pair <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>D</mi><mo stretchy="false">→</mo><mi>h</mi><mo stretchy="false">(</mo><msup><mrow><mi>h</mi></mrow><mrow><mrow><mo stretchy="false">(</mo><mo>′</mo><mo stretchy="false">)</mo></mrow></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></mrow></math>, based on <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>20.3</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math> 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></math> collision data collected at the center-of-mass energy of 3.773 GeV with the BESIII detector at BEPCII. No significant signals are observed, and the corresponding upper limits on the branching fractions at the 90% confidence level are determined. The sensitivities of the results are at the level of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mn>10</mn><mrow><mo>−</mo><mn>6</mn></mrow></msup><mo>∼</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>7</mn></mrow></msup></math>. The upper limits on the branching fractions for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>ρ</mi><mo>+</mo></msup><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>K</mi><mrow><mo>*</mo><mo>+</mo></mrow></msup><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mn>0</mn></msup><mo stretchy="false">→</mo><msubsup><mi>K</mi><mi>S</mi><mn>0</mn></msubsup><msubsup><mi>K</mi><mi>S</mi><mn>0</mn></msubsup><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mn>0</mn></msup><mo stretchy="false">→</mo><msup><mi>π</mi><mn>0</mn></msup><msup><mi>π</mi><mn>0</mn></msup><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mn>0</mn></msup><mo stretchy="false">→</mo><msup><mi>η</mi><mo>′</mo></msup><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> decay channels are measured for the first time. For the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mn>0</mn></msup><mo stretchy="false">→</mo><msup><mi>π</mi><mn>0</mn></msup><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mn>0</mn></msup><mo stretchy="false">→</mo><mi>η</mi><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mn>0</mn></msup><mo stretchy="false">→</mo><mi>ω</mi><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mn>0</mn></msup><mo stretchy="false">→</mo><msubsup><mi>K</mi><mi>S</mi><mn>0</mn></msubsup><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mn>0</mn></msup><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>K</mi><mo>+</mo></msup><msup><mi>π</mi><mn>0</mn></msup><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><msubsup><mi>K</mi><mi>S</mi><mn>0</mn></msubsup><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>K</mi><mo>+</mo></msup><msubsup><mi>K</mi><mi>S</mi><mn>0</mn></msubsup><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> decay channels, the upper limits on the branching fractions are determined, with an improvement of at least a factor of four compared to previous searches. The upper limits on the branching fractions for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mn>0</mn></msup><mo stretchy="false">→</mo><msup><mi>ρ</mi><mn>0</mn></msup><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mn>0</mn></msup><mo stretchy="false">→</mo><mi>ϕ</mi><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> decay channels are set at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>0.7</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>6</mn></mrow></msup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>4.6</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>6</mn></mrow></msup></math>, respectively.

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

Search for the rare decays of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mo stretchy="false">→</mo><mi>h</mi><mo stretchy="false">(</mo><msup><mi>h</mi><mrow><mrow><mo stretchy="false">(</mo><mo>′</mo><mo stretchy="false">)</mo></mrow></mrow></msup><mo stretchy="false">)</mo><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math>

We investigate the $$e^+ e^- \rightarrow \eta J/\psi $$ cross section by employing a model that combines relativistic Breit–Wigner amplitudes with a unitarized coupled-channel approach to account for resonant and non-resonant contributions, respectively. By performing a global fit to the BESIII experimental data, we determine the essential free parameters of the transition amplitudes. Furthermore, we analyze the role of a dynamically generated $$D\bar{D}^*$$ pole near 3.88 GeV and demonstrate its critical contribution to shaping the observed cross-section line shape.

Mexico

Sara Rahmani

Analysis of the $$e^+e^- \rightarrow \eta J/\psi $$ cross section within a unitarized coupled-channel approach

We present a next-to-next-to-leading-order (NNLO) calculation within the nonrelativistic QCD framework 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><msup><mi>Z</mi><mo>*</mo></msup><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>+</mo><mi>J</mi><mo>/</mo><mi>ψ</mi></math>. We find that the NNLO contribution is two to three times larger than the next-to-leading-order contribution, which itself is already three to five times larger than the leading-order result. In the high-energy limit, we provide analytic expressions for the leading-power coefficients in the asymptotic expansion of the two-loop amplitudes. Our results are directly applicable to the bottomonium process <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi><mo stretchy="false">→</mo><mi mathvariant="normal">ϒ</mi><mo>+</mo><mi mathvariant="normal">ϒ</mi></math>. Using the obtained hadronic amplitudes, we predict the decay width of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> boson into these rare dicharmonium and dibottomonium final states.

Switzerland

Xiang Chen

Xin Guan

Chuan-Qi He

Yan-Qing Ma

Two-loop QCD corrections to <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><msup><mi>Z</mi><mo>*</mo></msup><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>+</mo><mi>J</mi><mo>/</mo><mi>ψ</mi></math>

We investigate the sensitivity of present and future direct detection experiments to generalized neutrino interactions (GNI) with electrons through elastic neutrino-electron scattering. Using data from LUX-ZEPLIN, PandaX-4T, and XENONnT, we derive constraints on vector, axial-vector, scalar, and tensor effective couplings, and compare them with existing limits. Our results show that current xenon-based detectors already provide competitive bounds, with XENONnT offering the most stringent constraints due to its larger exposure and reduced backgrounds. Among the GNI couplings, the scalar contributions remain more weakly constrained, while tensor interactions yield the strongest limits. We also present projected sensitivities for the DARWIN experiment, showing potential improvements. These results demonstrate the capability of direct detection experiments, originally designed for dark matter searches, to provide complementary and competitive constraints on generalized neutrino interactions.

Jesús Celestino-Ramírez

Spain

F. Escrihuela

L. Flores

O. Miranda

R. Sánchez-Vélez

Searching for generalized neutrino interactions in direct detection experiments with E$\textit{ν}$ES

We demonstrate that chiral-odd dimeson generalized distribution amplitudes (CO-GDAs)—nonperturbative objects encoding the transition of a quark-antiquark pair into two mesons—can be accessed in high-energy <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> annihilation into two meson pairs, each with a relatively low invariant mass. While chiral-even GDAs contribute to the leading one-photon amplitude, the chiral-odd sector enters via two-photon exchange. We show that the interference between these amplitudes leads to specific effects which may be measurable at BES III or future tau-charm factories. This work opens a direct path to experimentally probing the long-missing chiral-odd sector of meson structure—specifically, the spin-orbit correlation in a spin-0 meson, in some contexts referred to as anomalous tensorial magnetic moment.

Shohini Bhattacharya

France

Renaud Boussarie

Bernard Pire

Lech Szymanowski

Revealing chiral-odd two-meson generalized distribution amplitudes in <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><mo stretchy="false">(</mo><mi>π</mi><mi>π</mi><mo stretchy="false">)</mo><mo stretchy="false">(</mo><mi>π</mi><mi>π</mi><mo stretchy="false">)</mo></math> reactions

The inclusive top quark pair ( $$t\bar{t}$$ ) cross-section $$\sigma _{t\bar{t}}$$ has been measured in proton–proton collisions at $$\sqrt{s}=13\,\text {TeV}$$ , using $$140\,{\text {fb}^{-1}} $$ of data collected by the ATLAS experiment at the Large Hadron Collider. Using events with an opposite-charge $$e\mu $$ pair and $\textit{b}$-tagged jets, the cross-section is measured to be: where the uncertainties reflect the limited size of the data sample, experimental and theoretical systematic effects, the integrated luminosity, and the proton beam energy, giving a total uncertainty of 1.3%. The result is used to determine the top quark pole mass via the dependence of the predicted cross-section on $${m_{t}^\textrm{pole}}$$ , giving $${m_{t}^\textrm{pole}}=172.8^{+1.5}_{-1.7}$$ $$\text {GeV}$$ . The same event sample is used to measure absolute and normalised differential cross-sections for the $$t\bar{t} \rightarrow e\mu \nu \bar{\nu }b\bar{b} $$ process as a function of single-lepton and dilepton kinematic variables. Complementary measurements of $$e\mu b\bar{b} $$ production, treating both $$t\bar{t}$$ and $\textit{Wt}$ events as signal, are also provided. Both sets of differential cross-sections are compared to the predictions of various Monte Carlo event generators, demonstrating that the state-of-the-art generators and $\textit{bb}$4$\textit{l}$ describe the data better than .

G. Aad

Norway

E. Aakvaag

B. Abbott

United Arab Emirates

S. Abdelhameed

K. Abeling

N. Abicht

S. Abidi

M. Aboelela

Morocco

A. Aboulhorma

Israel

H. Abramowicz

Y. Abulaiti

B. Acharya

A. Ackermann

C. Adam Bourdarios

L. Adamczyk

S. Addepalli

M. Addison

J. Adelman

A. Adiguzel

T. Adye

A. Affolder

Y. Afik

M. Agaras

A. Aggarwal

Romania

C. Agheorghiesei

Azerbaijan

F. Ahmadov

S. Ahuja

X. Ai

G. Aielli

A. Aikot

M. Tamlihat

B. Aitbenchikh

T. Åkesson

A. Akimov

Japan

D. Akiyama

N. Akolkar

S. Aktas

G. Alberghi

Canada

J. Albert

U. Alberti

P. Albicocco

G. Albouy

S. Alderweireldt

Z. Alegria

M. Aleksa

I. Aleksandrov

C. Alexa

Precise measurement of the $$t\bar{t}$$ production cross-section and lepton differential distributions in $$ e\mu $$ dilepton events from $$\sqrt{s}=13\,\text {TeV}$$ $\textit{pp}$ collisions with the ATLAS detector