The weak decays of charmonium states such as $ J/\psi $ and $ \psi(2S) $ are instrumental in probing both nonperturbative QCD dynamics and the flavor structure of the Standard Model (SM). The extreme rarity of charmonium weak decays renders them highly sensitive to physics beyond the SM, particularly in channels that are heavily suppressed in the SM, such as flavor-changing neutral-current (FCNC) decays. This review highlights the critical role of the BESIII experiment, which leverages an unprecedented data sample of over $ 10^{10} $ $ J/\psi $ and $ 2.7\times10^{9} $ $ \psi(2S) $ events to achieve leading sensitivity in searches for charmonium weak decays. We present the latest and most stringent upper limits established by BESIII on various semileptonic, nonleptonic, and FCNC charmonium weak decay channels.

China

Xu-Ze Li

Kai-Xin Fan

Zheng-Yun You

Yu Zhang

Minggang Zhao

Mini-review of charmonium weak decays at BESIII * Supported in part by the National Key R&D Program of China (2023YFA1606000); the National Natural Science Foundation of China (NSFC) (12035009, 12175321, U1932101), and the National College Students' Science and Technology Innovation Project of Sun Yat-sen University

We investigate the direct $\rm CP $ violation in the decay $ D^\pm \to \pi^\pm \pi^+ \pi^- $ incorporating the $ a_0^0(980) $ - $ f_0(980) $ mixing mechanism. The integrated mixing intensities $ \overline \xi_{fa} $ and $ \overline \xi_{af} $ are calculated using meson masses and coupling constants extracted from various theoretical models and experimental data, yielding values of appreciable magnitude. We find that when the invariant mass of the $ \pi^+\pi^- $ pair lies near the $ f_0(980) $ resonance, this isospin-breaking mechanism can enhance the $\rm CP $ asymmetry. The enhancement is particularly pronounced when the $ f_0(980) $ carries a significant $ n\bar{n} $ quark component and the $ f_0(980) $ and $ \sigma(600) $ mixing angle is approximately $ 26^\circ $ . After accounting for non-factorizable effects, we find these corrections tend to partially cancel the leading-order contributions, resulting in a suppression of the $\rm CP $ violations relative to the naive factorization predictions. It is emphasized that the $ a_0^0(980) $ - $ f_0(980) $ mixing mechanism should be taken into account in both theoretical and experimental studies of $\rm CP $ violation in $\textit{B}$ or $\textit{D}$ meson decays.

Shi-Ji Cao

Jing-Juan Qi

Yi-Fan Zhao

Chao Wang

Zhen-Yang Wang

Xin-Heng Guo

Direct CP violation in ${ {\boldsymbol D}^{\bf\pm }\to {\boldsymbol\pi}^{\bf\pm} {\boldsymbol\pi}^{\bf +} {\boldsymbol\pi}^{\bf -}} $ with ${{\boldsymbol a}_{\bf 0}^{\bf 0}{\bf (980)-}{\boldsymbol f}_{\bf 0}{\bf (980)}} $ mixing * Supported by the National Natural Science Foundation of China (12405115, 12105149, 11805153, 12275024), and the High-Level Scientific Research Fund of Ningbo University (GJPY2026032)

We constructed a four-Higgs-doublet model (4HDM) invariant under $\textit{D}$ $_{5}$ symmetry and investigated its complete neutral vacuum structure in detail. Assuming explicit CP conservation in the scalar potential, we examined whether CP symmetry can be spontaneously broken. We provided a complete list of all possible real and complex vacua, along with the constraints on the potential parameters required for each vacuum solution to exist. We also discussed the positive-definiteness conditions that the Hessian must satisfy for each vacuum to be a local minimum of the potential. The results show that, after spontaneous symmetry breaking, some complex vacua lead to spontaneous CP violation in the potential, whereas the remaining complex vacua still preserve CP conservation. Among these CP-violating complex vacua, one can be regarded as the most general form. Furthermore, we discussed the relationship between real and complex vacua.

Dong-Ping Fu

Michihisa Takeuchi

Spontaneous CP violation in the $\textit{D}$ $_{5}$-symmetric four-Higgs-doublet models * Supported by the Fundamental Research Funds for the Central Universities, the One Hundred Talent Program of Sun Yat-sen University, China, and the Guangdong Natural Science Foundation (2026A1515012641)

In this work, we present the multiplicity and yield of charged hadrons and particle ratios in d-Au collisions at $$\sqrt{s_{NN}}= 200$$ GeV using the PYTHIA8/Angantyr. The model reproduces the multiplicity ( $$N_{ch}$$ ) and pseudo-rapidity distribution reasonably well in minimum-biased d-Au collisions without assuming the formation of a thermalized medium. The invariant yield from Angantyr underpredicts the data in central collisions. We discussed the similarity between the nuclear modification factor $$R_{AA}$$ and data/MC from Angantyr and the possibility of using it as a model-dependent observable to check in-medium effects. The data/MC suggests that the central d-Au collisions exhibit signals like baryon enhancement, but no high $$p_T$$ suppression was found. The d-Au collisions have a much smaller invariant yield than the thermal model calculation for similar $$N_{part}$$ .

India

Satya Nayak

Akash Das

B. Singh

Separating non-collective effects in d-Au collisions

We study the semileptonic decays <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>B</mi><mi>s</mi></msub><mo stretchy="false">→</mo><msubsup><mi>D</mi><mi>s</mi><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msubsup><mi>τ</mi><mover accent="true"><mi>ν</mi><mo stretchy="false">¯</mo></mover></math> as a promising probe for new physics (NP) beyond the standard model (SM). The extension of the SM is done through the introduction of four-fermion operators beyond the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>V</mi><mo>−</mo><mi>A</mi></math> structure with the corresponding Wilson coefficients characterizing their contribution. The constraints on these coefficients are obtained from recent experimental data. Form factors describing hadron transitions are calculated in our covariant quark model with infrared confinement. Theoretical predictions for the full set of observables in these channels are provided. We analyze possible NP effects to be tested in future experiments.

JINR

M.A. Ivanov

J.N. Pandya

Italy

P. Santorelli

N.R. Soni

Vietnam

C.T. Tran

H.C. Tran

Vo Quoc Phong

Detailed analysis of possible new-physics effects in the semileptonic decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>B</mi><mi>s</mi></msub><mo stretchy="false">→</mo><msubsup><mi>D</mi><mi>s</mi><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msubsup><mi>τ</mi><mover accent="true"><mi>ν</mi><mo stretchy="false">¯</mo></mover></math>

Germany

Simon Mutke

Leon Heuser

Ingrid Dax

Bastian Kubis

Sweden

Stefan Leupold

Publisher Correction: Dispersive analysis of $\textit{D}$- and $\textit{B}$-meson form factors with chiral and heavy-quark constraints

We ask whether two classical time-machine geometries, the Ori (2005) compact-vacuum-core metric and the Ahmed (2018) four-dimensional generalisation of Misner space, remain admissible exact solutions when the gravitational sector is enlarged to the recently proposed $$f(R,\mathcal {L}_{m},\Phi ,X)$$ class, an extension of $$f(R,\mathcal {L}_{m})$$ that couples curvature, the matter Lagrangian density, a scalar field $$\Phi $$ , and its kinetic invariant $$X = g^{\mu \nu }\nabla _{\mu }\Phi \nabla _{\nu }\Phi $$ . Working with the explicit model $$f = R + \mathcal {L}_{m} + (\lambda /2)\,X$$ and a vanishing scalar potential, we compute the curvature invariants, the modified field equations, and the effective stress-energy components produced by the harmonic scalar profile $$\Phi (x,y) = a(x^{2}-y^{2})/2$$ in both backgrounds. The Ricci scalar vanishes for the Ori metric and obeys $$R = e^{f}(f_{,xx}+f_{,yy})$$ for the Ahmed metric; the kinetic invariant takes the explicit forms $$X = a^{2}(x^{2}+y^{2})$$ and $$X = a^{2}e^{f}(x^{2}+y^{2})$$ , respectively. Both metrics solve the field equations of the modified theory with anisotropic matter sources, and the chronology-violating regions $$g_{zz}<0$$ (Ori) and $$g_{\psi \psi }<0$$ (Ahmed) survive the modification. Energy-density profiles measured by a closed-timelike-curve observer match those measured by a static observer outside the chronology horizon, so the additional scalar degree of freedom in $$f(R,\mathcal {L}_{m},\Phi ,X)$$ gravity does not enforce a chronology-protection mechanism in either background. The conclusion mirrors the parallel result for the Li time-machine and supplies a consistency test for scalar-extended modified gravity in non-globally-hyperbolic settings.

Faizuddin Ahmed

Jordan

Ahmad Al-Badawi

Türkiye

İzzet Sakallı

Are Petrov type-N and D spacetimes admitting CTCs valid in $$f(R,\mathcal {L}_m,\Phi ,X)$$ gravity?

The <italic>&#947;d</italic>&#8239;&#8594;&#8239; <italic>K</italic> 0&#923; <italic>p</italic> reaction has been studied to search for a <math altimg='si30.svg'><mrow><mover accent='true'><mi>K</mi><mo>&#175;</mo></mover><mi>N</mi><mi>N</mi></mrow></math> quasi-bound state using the LEPS2 solenoid spectrometer at SPring-8. A localized enhancement concentrated at low <italic>q</italic> is observed in the ( <italic>M</italic> <inf>&#923;<italic>p</italic></inf>, <italic>q</italic>) distribution below the <math altimg='si8.svg'><mrow><msup><mi>K</mi><mo>&#8722;</mo></msup><mi>p</mi><mi>p</mi></mrow></math> mass threshold, where <italic>M</italic> <inf>&#923;<italic>p</italic></inf> is the &#923; <italic>p</italic> invariant mass and <math altimg='si31.svg'><mrow><mrow><mi>q</mi><mo>&#8801;</mo><mo>|</mo></mrow><msub><mover accent='true'><mi>p</mi><mo>&#8594;</mo></mover><mi>&#947;</mi></msub><mo linebreak='goodbreak'>&#8722;</mo><msub><mover accent='true'><mi>p</mi><mo>&#8594;</mo></mover><msup><mi>K</mi><mn>0</mn></msup></msub><mrow><mo>|</mo><mo>=</mo><mo>|</mo></mrow><msub><mover accent='true'><mi>p</mi><mo>&#8594;</mo></mover><mrow><mstyle mathvariant='normal'><mi>&#923;</mi></mstyle><mi>p</mi></mrow></msub><mrow><mo>|</mo></mrow></mrow></math> is the momentum transfer. A two-dimensional ( <italic>M</italic> <inf>&#923;<italic>p</italic></inf>, <italic>q</italic>) fit demonstrates that the enhancement near the threshold is statistically significant, yielding a local significance of 7.3&#8201; <italic>&#963;</italic>. The enhancement is characterized by effective shape parameters including the Breit&#8211;Wigner mass <italic>M</italic> and width &#915;, and a Gaussian form-factor momentum scale <italic>Q</italic>: <math altimg='si32.svg'><mrow><mi>M</mi><mo linebreak='goodbreak'>=</mo><mn>2.354</mn><mo>&#177;</mo><mn>0.011</mn><msubsup><mrow><mo>(</mo><mrow><mtext>stat</mtext><mo>.</mo></mrow><mo>)</mo></mrow><mrow><mo>&#8722;</mo><mn>0.005</mn></mrow><mrow><mo>+</mo><mn>0.009</mn></mrow></msubsup><mrow><mo>(</mo><mrow><mtext>syst</mtext><mo>.</mo></mrow><mo>)</mo></mrow><mspace width='0.33em' /><mtext>GeV</mtext><mo linebreak='goodbreak'>/</mo><msup><mi>c</mi><mn>2</mn></msup></mrow></math>, <math altimg='si33.svg'><mrow><mstyle mathvariant='normal'><mi>&#915;</mi></mstyle><mo linebreak='goodbreak'>=</mo><mn>0.055</mn><mo>&#177;</mo><mn>0.023</mn><msubsup><mrow><mo>(</mo><mrow><mtext>stat</mtext><mo>.</mo></mrow><mo>)</mo></mrow><mrow><mo>&#8722;</mo><mn>0.009</mn></mrow><mrow><mo>+</mo><mn>0.031</mn></mrow></msubsup><mrow><mo>(</mo><mrow><mtext>syst</mtext><mo>.</mo></mrow><mo>)</mo></mrow><mspace width='0.33em' /><mtext>GeV</mtext><mo linebreak='goodbreak'>/</mo><msup><mi>c</mi><mn>2</mn></msup></mrow></math>, and <math altimg='si34.svg'><mrow><mi>Q</mi><mo linebreak='goodbreak'>=</mo><mn>0.350</mn><mo>&#177;</mo><mn>0.041</mn><msubsup><mrow><mo>(</mo><mrow><mtext>stat</mtext><mo>.</mo></mrow><mo>)</mo></mrow><mrow><mo>&#8722;</mo><mn>0.010</mn></mrow><mrow><mo>+</mo><mn>0.035</mn></mrow></msubsup><mrow><mo>(</mo><mrow><mtext>syst</mtext><mo>.</mo></mrow><mo>)</mo></mrow><mspace width='0.33em' /><mtext>GeV</mtext><mo linebreak='goodbreak'>/</mo><mi>c</mi></mrow></math>. The obtained results support the existence of a <math altimg='si30.svg'><mrow><mover accent='true'><mi>K</mi><mo>&#175;</mo></mover><mi>N</mi><mi>N</mi></mrow></math> quasi-bound state in photoproduction.

Japan

R. Kobayakawa

South Korea

J.K. Ahn

S. Ajimura

Taiwan

W.C. Chang

M.L. Chu

S. Daté

T. Gogami

T.A. Hashimoto

T. Hotta

T. Ishikawa

H. Katsuragawa

H. Kohri

Y. Ma

M. Miyabe

K. Mizutani

N. Muramatsu

T. Nakano

T.H. Nam

M. Niiyama

Y. Nozawa

Y. Ohashi

H. Ohkuma

H. Ohnishi

T. Ohta

Canada

C. Rangacharyulu

S.Y. Ryu

Y. Sada

H. Shimizu

M. Sumihama

S. Suzuki

S. Tanaka

A.O. Tokiyasu

N. Tomida

K. Watanabe

T. Yorita

C. Yoshida

M. Yosoi

Evidence for a <math altimg='si30.svg'><mrow><mover accent='true'><mi>K</mi><mo>&#175;</mo></mover><mi>N</mi><mi>N</mi></mrow></math> quasi-bound state in the <italic>&#947;d</italic>&#8239;&#8594;&#8239; <italic>K</italic> 0&#923; <italic>p</italic> reaction

The persistent anomalies observed in <italic>B</italic> mesons related to <math altimg='si1.svg'><mrow><mi>b</mi><mo>&#8594;</mo><mi>s</mi><msup><mi>&#956;</mi><mo>+</mo></msup><msup><mi>&#956;</mi><mo>&#8722;</mo></msup></mrow></math> transitions point to the potential for new physics beyond the Standard Model. To explore this further, we conduct an analysis of the exclusive semileptonic decays <math altimg='si6.svg'><mrow><msub><mi>B</mi><mi>c</mi></msub><mo>&#8594;</mo><msubsup><mi>D</mi><mi>s</mi><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msubsup><msup><mi>&#956;</mi><mo>+</mo></msup><msup><mi>&#956;</mi><mo>&#8722;</mo></msup></mrow></math> within an effective field theory formalism. We perform a global fit to new (axial)vector couplings using the current experimental data for <math altimg='si1.svg'><mrow><mi>b</mi><mo>&#8594;</mo><mi>s</mi><msup><mi>&#956;</mi><mo>+</mo></msup><msup><mi>&#956;</mi><mo>&#8722;</mo></msup></mrow></math> transitions. We compute the branching ratios and physical observables such as forward-backward asymmetries, lepton polarization asymmetries, form factor independent observables for <math altimg='si6.svg'><mrow><msub><mi>B</mi><mi>c</mi></msub><mo>&#8594;</mo><msubsup><mi>D</mi><mi>s</mi><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msubsup><msup><mi>&#956;</mi><mo>+</mo></msup><msup><mi>&#956;</mi><mo>&#8722;</mo></msup></mrow></math>, both within the Standard Model and in new physics scenarios. Additionally, we examine the existence of lepton flavor universality violation in the <math altimg='si78.svg'><mrow><msub><mi>B</mi><mi>c</mi></msub><mo>&#8594;</mo><msubsup><mi>D</mi><mi>s</mi><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msubsup><msup><mi>&#8467;</mi><mo>+</mo></msup><msup><mi>&#8467;</mi><mo>&#8722;</mo></msup></mrow></math> process.

Manas Kumar Mohapatra

Ajay Kumar Yadav

Suchismita Sahoo

Signature of (axial)vector operators in <math altimg='si6.svg'><mrow><msub><mi>B</mi><mi>c</mi></msub><mo>&#8594;</mo><msubsup><mi>D</mi><mi>s</mi><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msubsup><msup><mi>&#956;</mi><mo>+</mo></msup><msup><mi>&#956;</mi><mo>&#8722;</mo></msup></mrow></math> decays

We investigate the vacuum-induced current density for a charged scalar field in a (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>D</mi><mo>+</mo><mn>1</mn></mrow></math>)-dimensional cosmic dispiration spacetime threaded by a magnetic flux. This background combines a cosmic string and a screw dislocation, yielding a nontrivial helical geometry. By constructing the normalized mode functions of the Klein-Gordon equation, we evaluate the Wightman function and obtain the vacuum expectation value of the current density. We show that, in addition to the azimuthal component describing a persistent current around the defect, a nonvanishing axial component is induced as a direct consequence of the helical structure of the spacetime. Both components are periodic functions of the magnetic flux depending only on its fractional part, reflecting the Aharonov-Bohm nature of the effect. Closed expressions are obtained for massive and massless fields in arbitrary dimensions. We demonstrate that the screw dislocation parameter plays a crucial role in the behavior of the induced currents, leading to the regularization of the components at the origin and controlling their magnitude. Their asymptotic behavior is also analyzed in detail. Our results reduce to known expressions in the absence of the screw dislocation, providing a consistency check. In particular, we examine the physically relevant (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>3</mn><mo>+</mo><mn>1</mn></mrow></math>)-dimensional case, where numerical analysis reveals nontrivial features arising from the interplay between topology and gauge effects.

Brazil

Herondy Mota

Vacuum-induced current density from a magnetic flux threading a cosmic dispiration in (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mo>+</mo><mn>1</mn></math>)-dimensional spacetime