We investigate the gravitational <math altimg='si1.svg'><mrow><msup><mi>e</mi><mo>&#8722;</mo></msup><mo linebreak='goodbreak'>+</mo><msup><mi>e</mi><mo>+</mo></msup><mo>&#8594;</mo><msup><mi>&#8467;</mi><mo>&#8722;</mo></msup><mo linebreak='goodbreak'>+</mo><msup><mi>&#8467;</mi><mo>+</mo></msup></mrow></math> scattering process within the framework of gravitoelectromagnetism, a weak-field approximation of gravity analogous to Maxwell&#8217;s theory of electromagnetism. This process involves the interaction between a fermion and an antifermion mediated by graviton exchange. We consider the nonminimal gravitational sector of the standard model extension and calculate the corrections to the scattering cross section arising from Lorentz violation. The analysis is carried out in two scenarios: (i) at zero temperature and (ii) at finite temperature. To incorporate thermal effects, we employ the thermo field dynamics formalism, which allows for a consistent treatment of quantum fields at finite temperature. The results provide insights into how Lorentz-violating and thermal corrections influence gravitational interactions, particularly relevant in high-energy or astrophysical environments.

Brazil

L.A.S. Evangelista

A.F. Santos

Gravitational Lorentz-violating <math altimg='si1.svg'><mrow><msup><mi>e</mi><mo>&#8722;</mo></msup><mo linebreak='goodbreak'>+</mo><msup><mi>e</mi><mo>+</mo></msup><mo>&#8594;</mo><msup><mi>&#8467;</mi><mo>&#8722;</mo></msup><mo linebreak='goodbreak'>+</mo><msup><mi>&#8467;</mi><mo>+</mo></msup></mrow></math> scattering

The measurement of the Higgs boson self-coupling is crucial for our understanding of the nature of electroweak symmetry breaking and potential physics beyond the Standard Model (BSM). In this work, we study in the framework of the 2-Higgs-Doublet Model (2HDM) the impact of one-loop corrections to triple Higgs couplings (THCs) on the pair production of two Standard Model (SM)-like Higgs bosons $\textit{h}$ at future high-energy $\textit{e}$ $\textit{e}$ colliders, focusing on the $\textit{e}$ $\textit{e}$ → $\textit{Zhh}$ process. By including the one-loop corrections to the THCs relevant for this process, i.e. the coupling between three SM-like Higgs bosons, $\textit{λ}$ , and between the non-SM-like Higgs $\textit{H}$, assumed to be heavier, and two SM-like Higgs bosons, $\textit{λ}$ , we account for the leading one-loop corrections to the di-Higgs production cross section. We show that the one-loop corrected THC $\textit{λ}$ can be enhanced up to nearly six times its SM value, which substantially enhances the di-Higgs production cross section w.r.t. the tree-level prediction, even in the alignment limit. On the other hand, one-loop corrections to $\textit{λ}$ can also enhance its value, potentially yielding to more prominent heavy Higgs $\textit{H}$ resonant production. We explore the sensitivity to the loop-corrected $\textit{λ}$ and the possible access to $\textit{λ}$ via the $\textit{H}$ resonant peak at a future high-energy $\textit{e}$ $\textit{e}$ collider, such as the ILC. We highlight the fact that including the one-loop corrected THCs can enhance the sensitivity to the $\textit{H}$ resonant peak, and therefore to $\textit{λ}$ . Finally, we discuss the required experimental precision at future $\textit{e}$ $\textit{e}$ colliders necessary to achieve these sensitivities.

Germany

F. Arco

Spain

S. Heinemeyer

M. Mühlleitner

Large one-loop effects of BSM triple Higgs couplings on double Higgs production at $\textit{e}$

The BESIII Collaboration has recently observed a resonant structure <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi><mo stretchy="false">(</mo><mn>4500</mn><mo stretchy="false">)</mo></math> 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><mi>J</mi><mo>/</mo><mi>ψ</mi><msup><mi>K</mi><mo>+</mo></msup><msup><mi>K</mi><mo>−</mo></msup></math>, whose origin remains unresolved. In this study, we analyze the cross section line shape 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>J</mi><mo>/</mo><mi>ψ</mi><msup><mi>K</mi><mo>+</mo></msup><msup><mi>K</mi><mo>−</mo></msup></math> by taking into account the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>4415</mn><mo stretchy="false">)</mo></math> state and intermediate charmed meson loops. By treating <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>4415</mn><mo stretchy="false">)</mo></math> as both a pure <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi></math>-wave state and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi><mo>−</mo><mi>D</mi></math> mixed states, and introducing the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>Z</mi><mrow><mi>c</mi><mi>s</mi></mrow><mrow><mo stretchy="false">(</mo><mo>′</mo><mo stretchy="false">)</mo></mrow></msubsup></math> resonance, we find that the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi><mo stretchy="false">(</mo><mn>4500</mn><mo stretchy="false">)</mo></math> peak at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>4.5</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math> arises from the triangle singularity mechanism in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>Z</mi><mrow><mi>c</mi><mi>s</mi></mrow><mrow><mo stretchy="false">(</mo><mo>′</mo><mo stretchy="false">)</mo></mrow></msubsup></math>-mediated rescattering processes, supporting its interpretation as a threshold effect rather than a conventional resonance.

China

Xiao-Yun Wang

Liu-Lin Wang

Xiao-Hai Liu

Qiang Zhao

Threshold effects as the origin of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi><mo stretchy="false">(</mo><mn>4500</mn><mo stretchy="false">)</mo></math> observed 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><mi>J</mi><mo>/</mo><mi>ψ</mi><msup><mi>K</mi><mo>+</mo></msup><msup><mi>K</mi><mo>−</mo></msup></math>

Light higgsinos with mass <math altimg='si10.svg'><mrow><mo>&#8764;</mo><mn>100</mn><mo linebreak='goodbreak'>&#8722;</mo><mn>400</mn></mrow></math> GeV are well-motivated from naturalness considerations within supersymmetric models. However, at hadron colliders such as CERN LHC, they are rather difficult to search for due to the small visible energy release from heavy higgsino decay to the lightest higgsino, assumed here to be the lightest SUSY particle (LSP). An alternative way to search for the sparticles of supersymmetry is via their virtual effects on electroweak precision observables (EWPO) such as the <italic>W</italic> boson mass or the effective weak mixing angle sin&#8201; 2 <italic>&#952;</italic> <inf>eff</inf>. We quantify the ability of an <math altimg='si3.svg'><mrow><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>&#8722;</mo></msup></mrow></math> Higgs factory operating at <math altimg='si11.svg'><mrow><msqrt><mi>s</mi></msqrt><mo>&#8764;</mo><mn>90</mn><mo linebreak='goodbreak'>&#8722;</mo><mn>250</mn></mrow></math> GeV to indirectly detect higgsinos via EWPO in the so-called <italic>higgsino discovery plane</italic>. The latter allows one to compare the relative reach of LHC and high-lumi LHC with an <math altimg='si3.svg'><mrow><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>&#8722;</mo></msup></mrow></math> Higgs factory and with a linear <math altimg='si3.svg'><mrow><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>&#8722;</mo></msup></mrow></math> collider operating at <math altimg='si12.svg'><mrow><msqrt><mi>s</mi></msqrt><mo>&#8764;</mo><mn>0.5</mn></mrow></math> TeV.

United States

Howard Baer

Vernon Barger

Japan

Natsumi Nagata

Italy

Dibyashree Sengupta

Reach of <math altimg='si3.svg'><mrow><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>&#8722;</mo></msup></mrow></math> Higgs factory for light higgsinos via electroweak precision observables and comparison with other future facilities

<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>γ</mi><mo>*</mo></msup><mi>γ</mi><mo stretchy="false">→</mo><mi>B</mi><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover></math> is the golden process to access chiral-even di-baryon generalized distribution amplitudes (GDAs) as deeply virtual Compton scattering has proven to be for the generalized parton distributions. In the framework of colinear quantum chromodynamics factorization, where the leading twist amplitude is the convolution of GDAs and a perturbatively calculable coefficient function, we study the scattering amplitude for the baryonic channels where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi></math> is a spin <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1</mn><mo>/</mo><mn>2</mn></math> baryon such as the nucleon or hyperon <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">Λ</mi></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">Σ</mi></mrow></math>. Taking into account the interfering quantum electrodynamics amplitude, we calculate the cross section of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>±</mo></msup><mi>γ</mi><mo stretchy="false">→</mo><msup><mi>e</mi><mo>±</mo></msup><mi>B</mi><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover></math> process, which can be experimentally studied 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></math> as well as in electron-ion facilities. We explore both the final state polarization summed case and the polarization dependent effects. Numerical estimates are presented for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>−</mo></msup><mi>γ</mi><mo stretchy="false">→</mo><msup><mi>e</mi><mo>−</mo></msup><mi>p</mi><mover accent="true"><mi>p</mi><mo stretchy="false">¯</mo></mover></math> using motivated models for GDAs. Our results show that a first extraction of baryon-antibaryon GDAs from experimental measurements is feasible at Belle II.

Jing Han

France

Bernard Pire

Qin-Tao Song

Accessing baryon-antibaryon generalized distribution amplitudes in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>±</mo></msup><mi>γ</mi><mo stretchy="false">→</mo><msup><mi>e</mi><mo>±</mo></msup><mi>B</mi><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover></math>

The small-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>x</mi></math> regime remains a key testing ground for perturbative QCD and future lepton-hadron collider physics. We demonstrate that the long-standing <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>∼</mo><mn>30</mn><mo>%</mo></math> spread among global next-to-next-to-leading-order parton distribution functions (PDFs) for heavy-flavor parton densities at small <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>x</mi></math> has now converged below <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>≈</mo><mn>17</mn><mo>%</mo></math>. Using the latest nnpdf4.0, ct18, and msht20 sets, we quantify a maximal relative deviation of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Δ</mi><mi>max</mi></msub><mo>≃</mo><mn>16.8</mn><mo>%</mo></math> at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>x</mi><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"><mi>Q</mi><mo>=</mo><mn>100</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>. This convergence, further stabilized by consistent <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>α</mi><mi>s</mi></msub></math> and scale variations, marks a new precision frontier for the heavy-flavor sector. We evaluate the phenomenological impact for heavy-quark electroproduction at future <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>e</mi><mi>p</mi></math> colliders (LHeC and FCC–eh), showing that PDF-driven cross section uncertainties for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>−</mo></msup><mi>p</mi><mo stretchy="false">→</mo><msup><mi>e</mi><mo>−</mo></msup><mi>c</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover><mi>X</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>−</mo></msup><mi>p</mi><mo stretchy="false">→</mo><msup><mi>e</mi><mo>−</mo></msup><mi>b</mi><mover accent="true"><mi>b</mi><mo stretchy="false">¯</mo></mover><mi>X</mi></math> have been reduced by nearly a factor of 2 compared to 2013 estimates.

Türkiye

S.O. Kara

Convergence of heavy-flavor parton distribution functions at small <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>x</mi></math> and its impact on future <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>e</mi><mi>p</mi></math> colliders

We investigate the production of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ϕ</mi><mo stretchy="false">(</mo><mn>2170</mn><mo stretchy="false">)</mo></math> state 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><mo stretchy="false">→</mo><mi>ϕ</mi><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup></math> reaction with the effective Lagrangian approach. In addition to the tree level contributions from the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ϕ</mi><mo stretchy="false">(</mo><mn>1680</mn><mo stretchy="false">)</mo></math> meson and a possible <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>X</mi><mo stretchy="false">(</mo><mn>1750</mn><mo stretchy="false">)</mo></math> state, we consider also the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn></mrow></msub><mtext>−</mtext><mi>K</mi><mtext>−</mtext><mover accent="true"><mrow><mi>K</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover></mrow></math> intermediate state process from the perspective of triangular singularity. Based on the one-photon exchange approximation, a pair of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>K</mi><mn>1</mn></msub><mover accent="true"><mi>K</mi><mo stretchy="false">¯</mo></mover></math> mesons was firstly produced, and then the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>K</mi><mn>1</mn></msub></math> meson subsequently decays into <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ϕ</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi></math>, and the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>K</mi><mover accent="true"><mi>K</mi><mo stretchy="false">¯</mo></mover></math> pair produce the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup></math> through the final state interactions, in which the scalar meson <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>f</mi><mn>0</mn></msub><mo stretchy="false">(</mo><mn>980</mn><mo stretchy="false">)</mo></math> is dynamically generated. We show that the inclusion of the triangle loop diagrams leads to a good description of the new BESIII measurements, especially for the structure of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ϕ</mi><mo stretchy="false">(</mo><mn>2170</mn><mo stretchy="false">)</mo></math>. This provides a novel interpretation of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ϕ</mi><mo stretchy="false">(</mo><mn>2170</mn><mo stretchy="false">)</mo></math> state, offering new insights into its fundamental nature, which are still unclear. Furthermore, it is found that these measurements on 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><mo stretchy="false">→</mo><mi>ϕ</mi><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup></math> reaction can be used to determine some of the properties of two <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>K</mi><mn>1</mn></msub></math> mesons with masses around 1613 MeV and 1890 MeV, which are crucial to reproduce the experimental data.

Xiang Wei

Qing-Hua Shen

Ju-Jun Xie

Shedding light on the nature of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ϕ</mi><mo stretchy="false">(</mo><mn>2170</mn><mo stretchy="false">)</mo></math> state 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><mo stretchy="false">→</mo><mi>ϕ</mi><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup></math> reaction

The top-quark Yukawa coupling is extracted from the distribution of the top-quark pair ( $$ t\overline{t} $$ ) invariant mass in proton-proton collisions using 140 fb of data at $$ \sqrt{s}=13 $$ TeV collected in 2015–2018 by the ATLAS experiment at the Large Hadron Collider. In the region near the production threshold, the $$ t\overline{t} $$ invariant mass spectrum is sensitive to electroweak virtual corrections, including contributions from Higgs boson exchange, thereby providing sensitivity to the top-quark Yukawa coupling. This is the first measurement in ATLAS that aims to obtain this coupling exploiting this approach. The $$ t\overline{t} $$ system is reconstructed in the single-lepton final state, requiring exactly one isolated electron or muon and at least four jets with at least two identified as originating from $\textit{b}$-quarks. The measured Yukawa coupling is found to be in good agreement with the Standard Model prediction. An upper limit on the top-quark Yukawa coupling strength of $\textit{Y}$ $\textit{<}$ 2$\textit{.}$1 relative to the Standard Model prediction is observed at 95% confidence level, consistent with the expected sensitivity.

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

United Kingdom

B. Acharya

A. Ackermann

C. Adam Bourdarios

Poland

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. Ait Tamlihat

B. Aitbenchikh

Sweden

T. Åkesson

A. Akimov

D. Akiyama

N. Akolkar

S. Aktas

G. Alberghi

Canada

J. Albert

Switzerland

U. Alberti

P. Albicocco

G. Albouy

S. Alderweireldt

Z. Alegria

M. Aleksa

I. Aleksandrov

C. Alexa

Greece

T. Alexopoulos

F. Alfonsi

M. Algren

M. Alhroob

Czechia

B. Ali

Saudi Arabia

H. Ali

S. Ali

S. Alibocus

South Africa

M. Aliev

G. Alimonti

W. Alkakhi

C. Allaire

B. Allbrooke

D. Allen

J. Allen

P. Allport

A. Aloisio

Argentina

F. Alonso

C. Alpigiani

Z. Alsolami

A. Alvarez Fernandez

M. Alves Cardoso

M. Alviggi

M. Aly

Y. Amaral Coutinho

A. Ambler

C. Amelung

M. Amerl

C. Ames

T. Amezza

D. Amidei

B. Amini

K. Amirie

A. Amirkhanov

Portugal

S. Amor Dos Santos

K. Amos

D. Amperiadou

S. An

C. Anastopoulos

T. Andeen

J. Anders

A. Anderson

A. Andreazza

S. Angelidakis

A. Angerami

A. Anisenkov

A. Annovi

C. Antel

E. Antipov

M. Antonelli

F. Anulli

Measurement of the top-quark Yukawa coupling from $$ t\overline{t} $$ production in the lepton+jets final state using $\textit{pp}$ collisions at $$ \sqrt{s}=13 $$ TeV with the ATLAS detector

H. Abreu

C. Bourdarios

J. Agarwala

W. Ahmed

M. Tamlihat

M. Akbiyik

K. Khoury

Chile

C. Flores

M. Estevez

A. Fernandez

M. Cardoso

Y. Coutinho

S. Santos

V. Ananiev

S. Andrean

Erratum: Precision measurement of the $$B^0$$ meson lifetime using $$B^0 \rightarrow J/\psi K^{*0}$$ decays with the ATLAS detector

By analyzing a data sample of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></math> collisions with center-of-mass energy <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msqrt><mrow><mi>s</mi></mrow></msqrt><mo>=</mo><mn>3.773</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math>, corresponding to an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>7.9</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math> collected with the BESIII detector operating at the BEPCII collider, we study semileptonic decays of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mrow><mn>0</mn><mo stretchy="false">(</mo><mo>+</mo><mo stretchy="false">)</mo></mrow></msup></math> mesons into the axial-vector meson <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>b</mi><mn>1</mn></msub><mo stretchy="false">(</mo><mn>1235</mn><mo stretchy="false">)</mo></math> via the decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>ω</mi><mi>π</mi></mrow></math>. The decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>D</mi></mrow><mrow><mn>0</mn></mrow></msup><mo stretchy="false">→</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mo>−</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>e</mi></mrow></msub></mrow></math> is observed with a significance of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>5.2</mn><mi>σ</mi></mrow></math> after considering systematic uncertainty, while evidence for the decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>D</mi></mrow><mrow><mo>+</mo></mrow></msup><mo stretchy="false">→</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>e</mi></mrow></msub></mrow></math> is obtained with a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>3.1</mn><mi>σ</mi></mrow></math> significance. The product branching fractions are determined to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">B</mi><mo stretchy="false">[</mo><msup><mrow><mi>D</mi></mrow><mrow><mn>0</mn></mrow></msup><mo stretchy="false">→</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mo>−</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>e</mi></mrow></msub><mo stretchy="false">]</mo><mo>×</mo><mi mathvariant="script">B</mi><mo stretchy="false">[</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mo>−</mo></mrow></msup><mo stretchy="false">→</mo><mi>ω</mi><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup><mo stretchy="false">]</mo><mo>=</mo><mo stretchy="false">(</mo><mn>0.72</mn><mo>±</mo><mn>0.1</mn><msubsup><mrow><mn>8</mn></mrow><mrow><mo>−</mo><mn>0.08</mn></mrow><mrow><mo>+</mo><mn>0.06</mn></mrow></msubsup><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">B</mi><mo stretchy="false">[</mo><msup><mrow><mi>D</mi></mrow><mrow><mo>+</mo></mrow></msup><mo stretchy="false">→</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>e</mi></mrow></msub><mo stretchy="false">]</mo><mo>×</mo><mi mathvariant="script">B</mi><mo stretchy="false">[</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mn>0</mn></mrow></msup><mo stretchy="false">→</mo><mi>ω</mi><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup><mo stretchy="false">]</mo><mo>=</mo><mspace linebreak="goodbreak"></mspace><mo stretchy="false">(</mo><mn>1.16</mn><mo>±</mo><mn>0.44</mn><mo>±</mo><mn>0.16</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></math>, where the first uncertainties are statistical and the second systematic. The ratio of their partial decay widths is determined to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">{</mo><mi mathvariant="normal">Γ</mi><mo stretchy="false">[</mo><msup><mrow><mi>D</mi></mrow><mrow><mn>0</mn></mrow></msup><mo stretchy="false">→</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mo stretchy="false">−</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo stretchy="false">+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>e</mi></mrow></msub><mo stretchy="false">]</mo><mo>/</mo><mn>2</mn><mi mathvariant="normal">Γ</mi><mo stretchy="false">[</mo><msup><mrow><mi>D</mi></mrow><mrow><mo stretchy="false">+</mo></mrow></msup><mo stretchy="false">→</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo stretchy="false">+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>e</mi></mrow></msub><mo stretchy="false">]</mo><mo stretchy="false">}</mo><mo>=</mo><mspace linebreak="goodbreak"></mspace><mn>0.78</mn><mo>±</mo><mn>0.1</mn><msubsup><mrow><mn>9</mn></mrow><mrow><mo>−</mo><mn>0.05</mn></mrow><mrow><mo>+</mo><mn>0.04</mn></mrow></msubsup></mrow></math>, which is consistent with unity, predicted by isospin invariance, within uncertainties.

M. Ablikim

Russia

M.N. Achasov

P. Adlarson

O. Afedulidis

X.C. Ai

R. Aliberti

A. Amoroso

Q. An

Y. Bai

JINR

O. Bakina

I. Balossino

Y. Ban

H.R. Bao

V. Batozskaya

Mongolia

K. Begzsuren

N. Berger

M. Berlowski

M. Bertani

D. Bettoni

F. Bianchi

Observation of the Singly Cabibbo Suppressed Decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mn>0</mn></msup><mo stretchy="false">→</mo><msub><mi>b</mi><mn>1</mn></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mo stretchy="false">)</mo><mo>−</mo></msup><msup><mi>e</mi><mo>+</mo></msup><msub><mi>ν</mi><mi>e</mi></msub></math> and Evidence for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>D</mi></mrow><mrow><mo>+</mo></mrow></msup><mo stretchy="false">→</mo><msub><mrow><mi>b</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1235</mn><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>e</mi></mrow></msub></mrow></math>