<p>In the heavy quarkonium decay process <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>V</mi><mo stretchy="false">→</mo><mi>g</mi><mi>g</mi><mi>g</mi></math> (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>V</mi><mo>=</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>,</mo><mi mathvariant="normal">ϒ</mi></math>), making a definite prediction including relativistic corrections has so far remained a significant challenge. In this work, we study this decay process by taking into account the relativistic corrections in the Bethe-Salpeter formalism, where the relativistic bound-state wave function of quarkonium is obtained by solving the Bethe-Salpeter equation under the covariant instantaneous ansatz. Through analytical calculation, we find that some polarized decay widths vanish due to the helicity selection rule, which suppresses the corresponding helicity amplitudes. Owing to helicity flip symmetry and phase space symmetry, the nonvanishing polarized decay widths are not all independent; they are related through a set of symmetry relations. Then we obtain the unpolarized decay width formula <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Γ</mi><mo stretchy="false">(</mo><mi>V</mi><mo stretchy="false">→</mo><mi>g</mi><mi>g</mi><mi>g</mi><mo stretchy="false">)</mo><mo>=</mo><mfrac><mrow><mn>80</mn><mo stretchy="false">(</mo><msup><mi>π</mi><mn>2</mn></msup><mo stretchy="false">−</mo><mn>9</mn><mo stretchy="false">)</mo><msubsup><mi>α</mi><mi>s</mi><mn>3</mn></msubsup><msubsup><mi>N</mi><mi>V</mi><mn>2</mn></msubsup><msubsup><mi>β</mi><mi>V</mi><mn>3</mn></msubsup></mrow><mrow><mn>81</mn><msup><mi>π</mi><mrow><mn>9</mn><mo stretchy="false">/</mo><mn>2</mn></mrow></msup><mi>M</mi></mrow></mfrac><mo stretchy="false">(</mo><mn>1</mn><mo>−</mo><mi>κ</mi><mfrac><msubsup><mi>β</mi><mi>V</mi><mn>2</mn></msubsup><msup><mi>M</mi><mn>2</mn></msup></mfrac><mo stretchy="false">)</mo></math>, where the factor <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>κ</mi><mfrac><msubsup><mi>β</mi><mi>V</mi><mn>2</mn></msubsup><msup><mi>M</mi><mn>2</mn></msup></mfrac></math> arises from the relativistic corrections with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>κ</mi><mo>≡</mo><mfrac><mrow><mn>3</mn><mo stretchy="false">(</mo><mn>112</mn><mo stretchy="false">+</mo><mn>25</mn><msup><mi>π</mi><mn>2</mn></msup><mo stretchy="false">)</mo></mrow><mrow><mn>16</mn><mo stretchy="false">(</mo><msup><mi>π</mi><mn>2</mn></msup><mo stretchy="false">−</mo><mn>9</mn><mo stretchy="false">)</mo></mrow></mfrac></math>. Furthermore, including both relativistic and QCD radiative corrections within the factorization assumption, our predictions of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><mi>V</mi><mo stretchy="false">→</mo><mi>g</mi><mi>g</mi><mi>g</mi><mo stretchy="false">)</mo></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><mi>V</mi><mo stretchy="false">→</mo><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mo stretchy="false">)</mo></math> agree well with their experimental data. As a crossing check, with the experimental value of the ratio <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>R</mi><mi>V</mi></msub><mo>=</mo><mfrac><mrow><mi mathvariant="normal">Γ</mi><mo stretchy="false">(</mo><mi>V</mi><mo stretchy="false">→</mo><mi>g</mi><mi>g</mi><mi>g</mi><mo stretchy="false">)</mo></mrow><mrow><mi mathvariant="normal">Γ</mi><mo stretchy="false">(</mo><mi>V</mi><mo stretchy="false">→</mo><msup><mi>e</mi><mo stretchy="false">+</mo></msup><msup><mi>e</mi><mo stretchy="false">−</mo></msup><mo stretchy="false">)</mo></mrow></mfrac></math> and our result for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>R</mi><mi>V</mi></msub></math>, we extract <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>α</mi><mi>s</mi></msub><mo stretchy="false">(</mo><msub><mi>M</mi><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></msub><mo>/</mo><mn>2</mn><mo stretchy="false">)</mo><mo>=</mo><mn>0.31</mn></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>α</mi><mi>s</mi></msub><mo stretchy="false">(</mo><msub><mi>M</mi><mi mathvariant="normal">ϒ</mi></msub><mo>/</mo><mn>2</mn><mo stretchy="false">)</mo><mo>=</mo><mn>0.20</mn></math>, respectively.</p>

China

Hong-Mei Jiang

Chao-Jie Fan

Jun-Kang He

Cui Kong

Heavy quarkonium decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>V</mi><mo stretchy="false">→</mo><mi>g</mi><mi>g</mi><mi>g</mi></math> with both relativistic and QCD radiative corrections

We present a search for solar axions produced through the axion-electron coupling ($\textit{g}$ ) using data from a novel 7-GridPix detector installed at the CERN Axion Solar Telescope (CAST). The detector, featuring ultra-thin silicon nitride windows and multiple veto systems, collected approximately 160 hours of solar tracking data between 2017–2018. Using machine learning techniques and the veto systems, we achieved a background rate of 1.06 × 10 keV cm s at a signal efficiency of about 80% in the 0.2 to 8 keV range. Analysis of the data yielded no significant excess above background, allowing us to set a new upper limit on the product of the axion-electron and axion-photon couplings of $\textit{g}$ · $\textit{g}$ < 7.35 × 10 GeV at 95% confidence level for axion masses below 10 meV. This result improves upon the previous best helioscope limit and demonstrates the potential of GridPix technology for rare event searches. Additionally, we derived a limit on the axion-photon coupling of $\textit{g}$ < 9.0 × 10 GeV at 95% CL, which, while not surpassing CAST’s best limit, provides complementary constraints on axion models.

Spain

K. Altenmüller

Greece

V. Anastassopoulos

Switzerland

S. Arguedas-Cuendis

France

S. Aune

Germany

J. Baier

K. Barth

H. Bräuninger

Italy

G. Cantatore

F. Caspers

J. Castel

Türkiye

S. Çetin

Denmark

F. Christensen

C. Cogollos

T. Dafni

M. Davenport

United States

T. Decker

K. Desch

D. Díez-Ibáñez

B. Döbrich

E. Ferrer-Ribas

H. Fischer

W. Funk

J. Galán

J. García

A. Gardikiotis

I. Giomataris

J. Golm

C. Hailey

Canada

M. Hasinoff

D. Hoffmann

I. Irastorza

J. Jacoby

A. Jakobsen

Croatia

K. Jakovčić

J. Kaminski

M. Karuza

S. Kostoglou

C. Krieger

B. Lakić

J. Laurent

G. Luzón

C. Malbrunot

C. Margalejo

M. Maroudas

South Korea

L. Miceli

H. Mirallas

P. Navarro

L. Obis

A. Özbey

K. Özbozduman

T. Papaevangelou

O. Pérez

M. Pivovaroff

Romania

M. Rosu

E. Ruiz-Chóliz

J. Ruz

T. Schiffer

S. Schmidt

M. Schumann

Y. Semertzidis

S. Solanki

L. Stewart

T. Vafeiadis

J. Vogel

K. Zioutas

Search for solar axions produced through the axion-electron coupling $\textit{g}$

We argue that $\textit{perturbatively flat vacua}$ (PFVs) introduced in $\textit{Phys. Rev. Lett.}$ (2020) 211603 are dual to M-theory compactifications on $\textit{G}$ -manifolds, enabling the enumeration of potentially novel $\textit{G}$ -manifolds via solutions to Diophantine equations in type IIB flux quanta. Independently, we show that warping corrections to the effective action of type IIB flux vacua grow parametrically at large complex structure, and we demonstrate that these corrections can nonetheless be captured by a classical geometric computation in M-theory.

Jakob Moritz

$\textit{G}$

In the context of fitting cosmological models, parameter degeneracy remains a central issue. This paper critically examines traditional methods for constraining parameters and focuses on the <italic>G</italic> factor as a tool for evaluating the quality of observational data. To ensure analytical independence, two datasets-Cosmic Chronometers (CC) and Baryon Acoustic Oscillations (BAO)-were utilized as samples for parameter fitting, supplemented by Markov Chain Monte Carlo (MCMC) simulations. The Figure of Merit (FoM) matrix served as the final criterion for assessing fitting performance. The results show that the <italic>G</italic> factor of the CC dataset increases linearly with redshift <italic>z</italic>, whereas the <italic>G</italic> factor of the BAO dataset follows a cubic relationship. Further analysis indicates that the FoM value for datasets with high <italic>G</italic> factors is significantly higher than that for datasets with low <italic>G</italic> factors, thereby validating the <italic>G</italic> factor&#8217;s effectiveness as a tool for assessing observational data quality and reducing parameter degeneracy. This suggests that the <italic>G</italic> factor may serve as a diagnostic tool and selection criterion for optimizing observational datasets in future research.

Yuan-Bo Xie

Yun-Dong Wu

Wei Hong

Tong-Jie Zhang

Exploring the cosmological model degeneracy with a new evaluate factor <italic>G</italic>

<p>The recent observation of multiple near-threshold structures 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> annihilation—including <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>3770</mn><mo stretchy="false">)</mo></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>G</mi><mo stretchy="false">(</mo><mn>3900</mn><mo stretchy="false">)</mo></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi><mo stretchy="false">(</mo><mn>3760</mn><mo stretchy="false">)</mo></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi><mo stretchy="false">(</mo><mn>3780</mn><mo stretchy="false">)</mo></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi><mo stretchy="false">(</mo><mn>3810</mn><mo stretchy="false">)</mo></math>—reveals limitations in existing models of charmonium and exotic hadrons. In this paper, we propose a unified coupled-channel description that simultaneously incorporates all five near-threshold structures using parameters constrained by hadron spectroscopy. Our model accurately reproduces the line shapes in both <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover></math> and nonopen-charm hadron (nOCH) channels, resolves the asymmetric profile of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>3770</mn><mo stretchy="false">)</mo></math>, and produces the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>G</mi><mo stretchy="false">(</mo><mn>3900</mn><mo stretchy="false">)</mo></math> bump. We identify the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi><mo stretchy="false">(</mo><mn>3780</mn><mo stretchy="false">)</mo></math> as the dominant manifestation of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>3770</mn><mo stretchy="false">)</mo></math>, attribute <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi><mo stretchy="false">(</mo><mn>3760</mn><mo stretchy="false">)</mo></math> to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">→</mo><mtext>nOCH</mtext></math> rescattering and suggest that <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi><mo stretchy="false">(</mo><mn>3810</mn><mo stretchy="false">)</mo></math> arises from coupling between the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>1</mn><mi>D</mi><mo stretchy="false">)</mo></math> state and the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>h</mi><mi>c</mi></msub><mi>π</mi><mi>π</mi></math> channel. The significant non-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover></math> decay of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>3770</mn><mo stretchy="false">)</mo></math> is explained by its near-threshold position. This analysis provides a coherent, unquenched framework centered on a charmonium <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ψ</mi><mo stretchy="false">(</mo><mn>1</mn><mi>D</mi><mo stretchy="false">)</mo></math> core for near-threshold phenomena and offers a predictive approach extendable to bottomonium systems and future data from Belle II.</p>

Ri-Qing Qian

Xiang Liu

Unified coupled-channel description for the five near-threshold structures <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>ψ</mi><mo stretchy="false">(</mo><mn>3770</mn><mo stretchy="false">)</mo></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>G</mi><mo stretchy="false">(</mo><mn>3900</mn><mo stretchy="false">)</mo></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi><mo stretchy="false">(</mo><mn>3760</mn><mo stretchy="false">)</mo></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi><mo stretchy="false">(</mo><mn>3780</mn><mo stretchy="false">)</mo></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi><mo stretchy="false">(</mo><mn>3810</mn><mo stretchy="false">)</mo></math> from <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

The DarkSide-20k dark matter direct detection experiment will employ a $${21}\,\hbox {m}^{2}$$ silicon photomultiplier (SiPM) array, instrumenting a dual-phase 50 tonnes liquid argon Time Projection Chamber (TPC). SiPMs are arranged into modular photosensors called $\textit{Tiles}$, each integrating 24 SiPMs onto a printed circuit board (PCB) that provides signal amplification, power distribution, and a single-ended output for simplified readout. $$16$$ Tiles are further grouped into $\textit{Photo-Detector Units}$ (PDUs). This paper details the production of the Tiles and the Quality Assurance and Quality Control (QA-QC) protocol established to ensure their performance and uniformity. The production and QA-QC of the Tiles are carried out at Nuova Officina Assergi (NOA), an ISO-6 clean room facility at LNGS. This process includes wafer-level cryogenic characterisation, precision die attaching, wire bonding, and extensive electrical and optical validation of each Tile. The overall production yield exceeds 83.5%, matching the requirements of the DarkSide-20k production plan. These results validate the robustness of the Tile design and its suitability for operation in a cryogenic environment.

F. Acerbi

P. Adhikari

P. Agnes

Poland

I. Ahmad

S. Albergo

Brazil

I. Albuquerque

T. Alexander

A. Alton

P. Amaudruz

M. Angiolilli

E. Aprile

M. Atzori Corona

D. Auty

M. Ave

Russia

I. Avetisov

O. Azzolini

H. Back

Z. Balmforth

A. Barrado Olmedo

P. Barrillon

G. Batignani

United Kingdom

P. Bhowmick

M. Bloem

S. Blua

V. Bocci

W. Bonivento

B. Bottino

M. Boulay

T. Braun

A. Buchowicz

S. Bussino

J. Busto

M. Cadeddu

M. Cadoni

R. Calabrese

V. Camillo

A. Caminata

N. Canci

M. Caravati

M. Cárdenas-Montes

N. Cargioli

M. Carlini

A. Castellani

P. Cavalcante

S. Cebrian

S. Chashin

A. Chepurnov

S. Choudhary

L. Cifarelli

B. Cleveland

Y. Coadou

V. Cocco

D. Colaiuda

E. Conde Vilda

L. Consiglio

A. Cortez

B. Costa

M. Czubak

M. D’Aniello

S. D’Auria

M. Rocha Rolo

A. Dainty

G. Darbo

S. Davini

R. de Asmundis

S. De Cecco

G. Dellacasa

A. Derbin

A. Devoto

L. Di Noto

P. Di Stefano

L. Dias

D. Díaz Mairena

C. Dionisi

G. Dolganov

F. Dordei

V. Dronik

F. Dylon

A. Elersich

E. Ellingwood

T. Erjavec

N. Fearon

M. Fernandez Diaz

L. Ferro

A. Ficorella

G. Fiorillo

D. Fleming

P. Franchini

D. Franco

H. Frandini Gatti

E. Frolov

F. Gabriele

D. Gahan

C. Galbiati

G. Galiński

G. Gallina

Production, quality assurance and quality control of the SiPM Tiles for the DarkSide-20k Time Projection Chamber