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

United States

Xin Guan

China

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 study the dissociative associated production of a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> meson and a dimuon via double parton scattering (DPS) in nucleus-proton ultraperipheral collisions. This new channel, characterized by a rapidity gap, is sensitive to the photon and gluon distributions of the proton. We derive a DPS pocket formula for this process, together with a corresponding expression for the effective cross section. Furthermore, we demonstrate the kinematic dependence of the effective cross section and present predictions for the differential DPS cross section at LHC and FCC energies.

Brazil

Bruna O. Stahlhöfer

Edgar Huayra

Emmanuel G. de Oliveira

Dissociative associated <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">J</mi><mo>/</mo><mi>ψ</mi></math> and dimuon production in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>A</mi><mi>p</mi></math> ultraperipheral collisions via double parton scattering

Motivated by the first LHCb searches for the rare $$ {\overline{B}}_{s,d}^0 $$ → $\textit{J}$/$\textit{ψμ}$ $\textit{μ}$ decays, we perform a detailed study of these processes within the QCD factorization formalism. Since the transverse size of the $\textit{J}$/$\textit{ψ}$ meson is small in the heavy quark mass limit, this formalism is generally expected to hold for these decays. We include both the leading- and next-to-leading-order QCD corrections to the hard-scattering kernels, which are convoluted with the light-cone distribution amplitudes (LCDAs) of the initial- and final-state hadrons. It is numerically found that, depending on the model parameters for the leading-twist $\textit{B}$-meson LCDA, the maximum branching ratios of $$ {\overline{B}}_s^0 $$ → $\textit{J}$/$\textit{ψμ}$ $\textit{μ}$ and $$ {\overline{B}}_d^0 $$ → $\textit{J}$/$\textit{ψμ}$ $\textit{μ}$ , integrated over the dimuon invariant mass squared $\textit{q}$ from 1 GeV to ( $$ {m}_{B_{s,d}} $$ − $\textit{m}$ ) , can reach up to 2.21 × 10 and 7.69 × 10 at the leading order in $\textit{α}$ , respectively. After incorporating the non-factorizable one-loop vertex corrections, these branching ratios are further reduced by about one order of magnitude, with $$ \mathcal{B}{\left.\left({\overline{B}}_s^0\to J/\psi {\mu}^{+}{\mu}^{-}\right)\right|}_{q^2\ge 1{\textrm{GeV}}^2} $$ = 2.88 × 10 and $$ \mathcal{B}{\left.\left({\overline{B}}_d^0\to J/\psi {\mu}^{+}{\mu}^{-}\right)\right|}_{q^2\ge 1{\textrm{GeV}}^2} $$ = 1.07 × 10 . In addition, we have presented the dimuon invariant mass distributions of the individual and total helicity amplitudes squared, as well as the differential and integrated longitudinal polarization fractions of the $\textit{J}$/$\textit{ψ}$ meson, which could be probed by the future LHCb and Belle II experiments with more accumulated data.

Xin-Qiang Li

Yan Shi

Ya-Dong Yang

Xing-Bo Yuan

Chun-Yang Zhao

$$ {\overline{B}}_{s,d}^0 $$ → $\textit{J}$/$\textit{ψμ}$ + $\textit{μ}$ − decays in QCD factorization

The decay of light bosonic dark matter particles can produce a bright electron/positron (<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>) flux that can be strongly constrained by local Voyager observations of the direct <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> flux, as well as 511 keV line and x-ray continuum observations 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> emission. We carefully analyze 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></math> yield and resulting cosmic ray and x-ray spectra from theoretically well-motivated light dark matter models, including (a) electrophilic axion-like particles, (b) dark photons, (c) scalars, and (d) <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo>−</mo><mi>L</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>L</mi><mi>i</mi></msub><mo>−</mo><msub><mi>L</mi><mi>j</mi></msub></math> vector bosons. We use the morphology and spectrum of the INTEGRAL 511 keV line data, the eROSITA x-ray continuum spectrum and the Voyager <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> spectrum to constrain the decay lifetime and coupling of each dark matter model. We find that 511 keV observations typically set world-leading limits on bosonic dark matter decay below masses of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>∼</mo><mn>1</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>, while eROSITA observations provide the strongest constraints in the range from 1–10 GeV. Finally, we forecast future limits from 21 cm line searches with next-generation HERA data.

Sweden

Thong T.Q. Nguyen

Spain

Pedro De la Torre Luque

Italy

Isabelle John

United Kingdom

Shyam Balaji

Pierluca Carenza

Germany

Tim Linden

INTEGRAL, eROSITA and Voyager constraints on light bosonic dark matter: ALPs, dark photons, scalars, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo>−</mo><mi>L</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>L</mi><mi>i</mi></msub><mo>−</mo><msub><mi>L</mi><mi>j</mi></msub></math> vectors

In this work, we distinguish the isospin for the first time and study the diquark–diquark–antiquark type $$udsc\bar{c}$$ pentaquark states with zero isospin via the QCD sum rules systematically. We distinguish contributions of the pentaquark states with negative parity from positive parity unambiguously and obtain clean QCD sum rules for the pentaquark states with negative parity. Then we adopt the modified energy scale formula to choose the optimal energy scales of the QCD spectral densities, and obtain the mass spectrum of the $$udsc\bar{c}$$ pentaquark states with the quantum numbers $$I=0$$ and $$J^{P}={\frac{1}{2}}^-$$ , $${\frac{3}{2}}^-$$ , $${\frac{5}{2}}^-$$ , which could interpret the $$P_{cs}(4338)$$ and $$P_{cs}(4459)$$ in the $$J/\psi \Lambda $$ mass spectrum naturally.

Zhi-Gang Wang

Qi Xin

Analysis of the hidden-charm pentaquark candidates in the $$J/\psi \Lambda $$ mass spectrum via the QCD sum rules

A novel machine-learning-based flavor-tagging algorithm combining same-side and opposite-side tagging is used to obtain the equivalent of 27 500 tagged <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>B</mi><mi>s</mi><mn>0</mn></msubsup><mo stretchy="false">→</mo><mi>J</mi><mo stretchy="false">/</mo><mi>ψ</mi><mi>ϕ</mi><mo stretchy="false">(</mo><mn>1020</mn><mo stretchy="false">)</mo></math> decays from <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>, collected by the CMS experiment and corresponding to an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>96.5</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math>. A time- and flavor-dependent angular analysis of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mrow><msup><mrow><mi>μ</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>μ</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow><mrow><msup><mrow><mi>K</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>K</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></mrow></math> final state, consistent with a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mrow><mi>ϕ</mi><mo stretchy="false">(</mo><mn>1020</mn><mo stretchy="false">)</mo></mrow><mo stretchy="false">→</mo><mrow><msup><mrow><mi>K</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>K</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></mrow></math> decay, is used to measure parameters of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>B</mi><mi>s</mi><mn>0</mn></msubsup><mo>−</mo><msubsup><mover accent="true"><mi>B</mi><mo accent="true" stretchy="false">¯</mo></mover><mi>s</mi><mn>0</mn></msubsup></math> system. The weak phase is measured to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>ϕ</mi></mrow><mrow><mi mathvariant="normal">s</mi></mrow></msub><mo>=</mo><mrow><mo>−</mo><mn>73</mn></mrow><mo>±</mo><mn>22</mn><mrow><mo stretchy="false">(</mo><mi>stat</mi><mo stretchy="false">)</mo></mrow><mo>±</mo><mn>10</mn><mrow><mo stretchy="false">(</mo><mi>syst</mi><mo stretchy="false">)</mo></mrow><mtext> </mtext><mtext> </mtext><mi>mrad</mi></mrow></math>, which, combined with the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msqrt><mrow><mi>s</mi></mrow></msqrt><mo>=</mo><mn>8</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></mrow></math> CMS result, gives <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>ϕ</mi></mrow><mrow><mi mathvariant="normal">s</mi></mrow></msub><mo>=</mo><mrow><mo>−</mo><mn>75</mn></mrow><mo>±</mo><mn>23</mn><mtext> </mtext><mtext> </mtext><mi>mrad</mi></mrow></math>. This value differs from zero by 3.2 standard deviations, providing the first evidence for mixing-induced <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> violation in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>B</mi><mi>s</mi><mn>0</mn></msubsup><mo stretchy="false">→</mo><mi>J</mi><mo stretchy="false">/</mo><mi>ψ</mi><mi>ϕ</mi><mo stretchy="false">(</mo><mn>1020</mn><mo stretchy="false">)</mo></math> decays. All measured physics parameters are found to agree with standard model predictions where available.

Armenia

A. Hayrapetyan

A. Tumasyan

Austria

W. Adam

J.W. Andrejkovic

L. Benato

T. Bergauer

S. Chatterjee

K. Damanakis

M. Dragicevic

P.S. Hussain

M. Jeitler

N. Krammer

A. Li

D. Liko

I. Mikulec

J. Schieck

R. Schöfbeck

D. Schwarz

M. Sonawane

W. Waltenberger

C.E. Wulz

Belgium

T. Janssen

T. Van Laer

P. Van Mechelen

N. Breugelmans

J. D’Hondt

S. Dansana

A. De Moor

M. Delcourt

F. Heyen

S. Lowette

I. Makarenko

D. Müller

S. Tavernier

M. Tytgat

G.P. Van Onsem

S. Van Putte

D. Vannerom

B. Bilin

B. Clerbaux

A.K. Das

I. De Bruyn

G. De Lentdecker

H. Evard

L. Favart

P. Gianneios

J. Jaramillo

A. Khalilzadeh

F.A. Khan

K. Lee

A. Malara

S. Paredes

M.A. Shahzad

L. Thomas

M. Vanden Bemden

C. Vander Velde

P. Vanlaer

M. De Coen

D. Dobur

G. Gokbulut

Y. Hong

J. Knolle

L. Lambrecht

D. Marckx

K. Mota Amarilo

K. Skovpen

N. Van Den Bossche

J. van der Linden

L. Wezenbeek

A. Benecke

A. Bethani

G. Bruno

C. Caputo

J. De Favereau De Jeneret

C. Delaere

I.S. Donertas

A. Giammanco

A.O. Guzel

Sa. Jain

V. Lemaitre

J. Lidrych

P. Mastrapasqua

T.T. Tran

G.A. Alves

E. Coelho

G. Correia Silva

C. Hensel

T. Menezes De Oliveira

C. Mora Herrera

P. Rebello Teles

M. Soeiro

A. Vilela Pereira

W.L. Aldá Júnior

M. Barroso Ferreira Filho

H. Brandao Malbouisson

W. Carvalho

J. Chinellato

E.M. Da Costa

G.G. Da Silveira

D. De Jesus Damiao

First Evidence for Mixing-Induced <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> Violation in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>B</mi><mi>s</mi><mn>0</mn></msubsup><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><mi>ϕ</mi><mo stretchy="false">(</mo><mn>1020</mn><mo stretchy="false">)</mo></math> Decays 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"><mrow><msqrt><mrow><mi>s</mi></mrow></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></mrow></math>

We investigate gluonic hidden-charm tetraquark states composed of two valence quarks, two valence antiquarks and an explicit valence gluon. In the color configuration $$[\bar{3}_c]_{c q}\otimes [8_c]_{G}\otimes [3_c]_{\bar{c}\bar{q}}$$ , a complete set of eight interpolating currents is constructed for states with quantum numbers $$^{PC}=0^{++}$$ , $$0^{-+},$$ $$0^{-}{-}$$ , and $$0^{+-}$$ . The corresponding mass spectra are systematically analysed within the QCD sum rule framework, including nonperturbative condensate contributions up to dimension eight. Our numerical analysis indicates the possible existence of six gluonic hidden-charm tetraquark states exhibiting stable behaviour in the adopted Borel windows. By replacing the charm quark with the bottom quark, masses for the corresponding hidden-bottom partners are also estimated. Possible production mechanisms and dominant decay channels are discussed, providing phenomenological guidance for experimental searches. These predicted states may be accessible at current and forthcoming facilities, including Belle II, PANDA, SuperB and LHCb, and thus offer an opportunity to probe explicit gluonic degrees of freedom in multiquark systems and deepen our understanding of nonperturbative QCD.

Bing-Dong Wan

Ming-Yang Yuan

Jun-Hao Zhang

Yan Zhang

Spectrum of $$J^{PC} = 0^{\pm \pm }$$ gluonic hidden-charm tetraquark states

The first observation of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mi>χ</mi><mrow><mi>c</mi><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>3872</mn><mo stretchy="false">)</mo></mrow><mo stretchy="false">→</mo><mrow><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow><msup><mi>μ</mi><mo>+</mo></msup><msup><mi>μ</mi><mo>−</mo></msup></mrow></math> decay is reported using proton-proton collision data recorded with the LHCb detector corresponding to an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>9</mn><mtext> </mtext><mtext> </mtext><msup><mrow><mi>fb</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math>. The decay mode is observed for the first time, with a significance of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>6.5</mn><mi>σ</mi></math>. Its branching fraction is measured relative to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mi>χ</mi><mrow><mi>c</mi><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>3872</mn><mo stretchy="false">)</mo></mrow><mo stretchy="false">→</mo><mrow><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup></mrow></math> decay mode <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mfrac><mrow><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><mrow><msub><mrow><mi>χ</mi></mrow><mrow><mi>c</mi><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>3872</mn><mo stretchy="false">)</mo></mrow><mo stretchy="false">→</mo><mrow><mrow><mi>J</mi><mo stretchy="false">/</mo><mi>ψ</mi></mrow><msup><mrow><mi>μ</mi></mrow><mrow><mo stretchy="false">+</mo></mrow></msup><msup><mrow><mi>μ</mi></mrow><mrow><mo stretchy="false">−</mo></mrow></msup></mrow><mo stretchy="false">)</mo></mrow><mrow><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><mrow><msub><mrow><mi>χ</mi></mrow><mrow><mi>c</mi><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>3872</mn><mo stretchy="false">)</mo></mrow><mo stretchy="false">→</mo><mrow><mrow><mi>J</mi><mo stretchy="false">/</mo><mi>ψ</mi></mrow><msup><mrow><mi>π</mi></mrow><mrow><mo stretchy="false">+</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo stretchy="false">−</mo></mrow></msup></mrow><mo stretchy="false">)</mo></mrow></mfrac><mo>=</mo><mrow><mo stretchy="false">(</mo><mn>1.68</mn><mo>±</mo><mn>0.32</mn><mo>±</mo><mn>0.05</mn><mo stretchy="false">)</mo></mrow><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>3</mn></mrow></msup></mrow></math>, where the first uncertainty includes both statistical contributions and systematic contributions which are uncorrelated between data-taking periods, and the second represents the systematic contributions that are correlated between data-taking periods.

Netherlands

R. Aaij

A.S.W. Abdelmotteleb

C. Abellan Beteta

F. Abudinén

T. Ackernley

A.A. Adefisoye

B. Adeva

M. Adinolfi

P. Adlarson

France

C. Agapopoulou

C.A. Aidala

Z. Ajaltouni

S. Akar

K. Akiba

Poland

M. Akthar

P. Albicocco

J. Albrecht

R. Aleksiejunas

CERN

F. Alessio

P. Alvarez Cartelle

R. Amalric

S. Amato

J.L. Amey

Y. Amhis

L. An

L. Anderlini

M. Andersson

P. Andreola

M. Andreotti

S. Andres Estrada

A. Anelli

D. Ao

C. Arata

F. Archilli

Z. Areg

M. Argenton

Costa Rica

S. Arguedas Cuendis

L. Arnone

Russia

A. Artamonov

M. Artuso

Observation of the decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>χ</mi><mrow><mi>c</mi><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>3872</mn><mo stretchy="false">)</mo><mo stretchy="false">→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><msup><mi>μ</mi><mo>+</mo></msup><msup><mi>μ</mi><mo>−</mo></msup></math>