We assess the impact of measuring deeply virtual Compton scattering (DVCS) off protons using the planned detector at the Electron-Ion Collider in China (EicC), which is proposed as an upgrade to the High Intensity Heavy-Ion Accelerator Facility (HIAF). We develop a neural-network architecture to flexibly parameterize Compton form factors (CFFs), reliably extrapolate into unmeasured kinematic regions, and provide robust uncertainty estimates using the replica method. The framework is fitted to available worldwide DVCS data using the $ {\mathrm{Gepard}}$ software. We find a significant reduction in the uncertainties of all CFFs after incorporating pseudo-data from single and double polarization asymmetries at the EicC, with particularly strong improvements in the sea-quark region.

China

Yuan-Yuan Huang

Xu Cao

Taifu Feng

Croatia

Krešimir Kumerički

Yu Lu

Assessing the impact of the Electron-Ion Collider in China on deeply virtual Compton scattering * Supported by the National Key R&D Program of China (2023YFA1606703), the National Natural Science Foundation of China (12547111, 12235008, 12405105) and (PK.1.1.10.0004) co-financed by the European Union and through the European Regional Development Fund - Competitiveness and Cohesion Programme 2021-2027. TF also thanks the Hebei Natural Science Foundation (A2022201017, A2023201041) and Natural Science Foundation of Guangxi Autonomous Region (2022GXNSFDA035068)

We revisit the holographic description of heavy-light mesons in the D3/D7 system at zero temperature, analyzing the dynamics of the coupled probe D7-branes through the non-Abelian Dirac-Born-Infeld action. Distinct quark masses are realized by separating the flavor branes, producing holographic flavor hierarchies. We refine the calculation made in previous works: we impose Hermiticity on the induced metric and fix the expansion of the determinant for matrix-valued fields. Implementing these improvements yields modified fluctuation equations and quantitatively different meson spectra: the scalar modes become heavier while the vector modes become lighter, removing the degeneracy reported in the literature. At finite ’t Hooft coupling, we also observe a qualitatively different dependence of the vector modes on the quark masses. The resulting prescription provides a consistent, broadly applicable framework for incorporating non-Abelian flavor dynamics into holographic models and can be readily extended to situations away from the vacuum.

Spain

Carlos Hoyos

Finland

Niko Jokela

Italy

Andrea Olzi

Subtleties of non-Abelian D-brane actions and their effect on holographic heavy-light meson spectra

In this work, we conduct a systematic investigation of the electromagnetic properties, specifically the magnetic moments and the M1 radiative decay behavior, of the predicted $$\Xi _c^{(',*)}D^{(*)}_s$$ -type double-charm hidden-strangeness molecular pentaquarks. The study is carried out within the framework of the constituent quark model to evaluate these electromagnetic observables, and our analysis incorporates three distinct scenarios: single-channel analysis, $\textit{S}$–$\textit{D}$ wave mixing analysis, and coupled-channel analysis. The calculated magnetic moments reveal characteristic patterns that reflect their underlying constituent configurations and provide sensitive probes for their quantum number assignments. Furthermore, we identify several M1 radiative decay channels with sizable widths that may offer promising signatures for future experimental detection. These M1 transitions also act as sensitive probes into their inner structures, displaying distinctive features that help differentiate between their constituent configurations and quantum number assignments. We anticipate that this study will stimulate experimental interest in exploring the electromagnetic properties of the $$\Xi _c^{(',*)}D^{(*)}_s$$ molecular states, thereby advancing our structural understanding of these exotic hadronic states.

Sheng-He Zhu

Fu-Lai Wang

Xiang Liu

Electromagnetic characteristics as probes into the inner structures of the predicted $$\Xi _c^{(',*)}D^{(*)}_s$$ molecular states

The recent ATOMKI experiments provided evidence pointing towards the existence of an X17 boson in the anomalous nuclear transitions of Beryllium-8, Helium-4, and Carbon-12. In this work, we consider X17 boson contributions to the previously measured $\textit{D}$ meson decays which include $$D_s^{*+} \rightarrow D_s^+ e^+ e^-$$ , $$D_s^{*+} \rightarrow D_s^+ \gamma $$ , $$D^{*0} \rightarrow D^0 e^+ e^-$$ , and $$D^{*0} \rightarrow D^0 \gamma $$ , as well as the measured decays of $$\psi (2S) \rightarrow \eta _c e^+ e^-$$ , $$\psi (2S) \rightarrow \eta _c \gamma $$ , $$\phi \rightarrow \eta e^+ e^-$$ , and $$\phi \rightarrow \eta \gamma $$ . Using the data of the above meson decays, we perform a fitting to the coupling parameters $$\varepsilon _u, \varepsilon _c$$ , and $$\varepsilon _s$$ by treating the couplings $$\varepsilon _u$$ and $$\varepsilon _c$$ as independent from each other rather than assuming the generation universality $$\varepsilon _u =\varepsilon _c$$ . It is found that the above fitting renders $$|\varepsilon _c|=7.6\times 10^{-3}$$ , $$|\varepsilon _s|=2.4\times 10^{-3}$$ and a huge magnitude for $$\varepsilon _u$$ , which is in serious tension with $$\left| \varepsilon _u\right| $$ determined from ATOMKI measurements. Using our fitted range for $$\varepsilon _c$$ and the range for $$\varepsilon _d$$ from ATOMKI measurements, we predict the range for $$D^{*+} \rightarrow D^{+} e^+ e^-$$ decay rate.

Fei-Fan Lee

Taiwan

Lam Uyen

Guey-Lin Lin

Testing the hypothesis of vector X17 boson by $$D$$ meson, charmonium, and $$\phi $$ meson decays

In the presence of a strong electric field, the vacuum is unstable to the production of pairs of charged particles—the Schwinger effect. The created pairs extract energy from the electric field, resulting in nontrivial backreaction. In this paper, we study <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>1</mn><mo>+</mo><mn>1</mn><mi mathvariant="normal">D</mi></mrow></math> massive QED subject to strong external electric fields in a self-consistent and fully quantum manner. We use the bosonized version of the theory, which attains a cosine interaction term in the presence of nonzero fermion mass <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>m</mi></math>. However, the assumption of a strong electric field justifies a perturbative treatment of the cosine interaction, i.e., an expansion in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>m</mi></math>. We calculate the vacuum expectation value of the electric field to first order in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>m</mi></math> and show that—surprisingly—it satisfies a classical nonlinear partial differential equation (related to the sine-Gordon equation). We show that the electric field exhibits dissipation-free oscillations (analogous to ordinary plasma oscillations) and calculate the plasma frequency analytically. We also compare to the semiclassical approximation commonly used to study backreaction, showing that it fails to capture the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>O</mi><mo stretchy="false">(</mo><mi>m</mi><mo stretchy="false">)</mo></math> shift in the plasma frequency.

Samuel E. Gralla

Morifumi Mizuno

Schwinger effect with backreaction in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>1</mn><mo>+</mo><mn>1</mn><mi mathvariant="normal">D</mi></mrow></math> massive QED with a strong external field

A striking prediction of QCD on the properties of the novel Transverse Momentum Dependent (TMD) distribution functions is that the time-reversal odd Sivers and Boer-Mulders functions extracted from semi-inclusive deep-inelastic scattering (SIDIS) will undergo a sign reversal in the Drell-Yan (DY) process. This prediction has been tested by experiments that have focused on the Sivers functions so far. We review the current status on the theoretical prediction and experimental extraction of the signs of the Boer-Mulders functions from SIDIS and DY. We note that the existing SIDIS and DY data are consistent with the predicted sign reversal of the Boer-Mulders functions for proton’s valence quark distribution. Prospects for future experiments at EIC capable of testing the sign reversal of the pion Boer-Mulders functions are also discussed.

United States

Jen-Chieh Peng

Ming-Xiong Liu

Guanghua Xu

Sign reversal of Boer-Mulders functions from semi-inclusive deep-inelastic scattering to the Drell-Yan process

Our understanding of high-lying states within the charmonium family remains incomplete, particularly in light of recent observations of charmonium states at energies around 4 GeV. In this study, we investigate the spectroscopic properties of several high-lying charmonia, focusing on the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2</mn><mi>D</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1</mn><mi>F</mi></math> states. A mass spectrum analysis is conducted, incorporating the unquenched effects. We then present a detailed study of the strong decay properties, including partial decay widths for two-body strong decays permitted by the Okubo-Zweig-Iizuka rule. Additionally, we explore the primary radiative decay channels associated with these states. Finally, we discuss the radiative transitions of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2</mn><mi>D</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1</mn><mi>F</mi></math> states via <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. Theoretical predictions provided here aim to guide future experimental searches for high-lying charmonium states at facilities such as BESIII, Belle II, LHCb, and the future Super <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math>–Charm Facility.

Cheng-Xi Liu

Zi-Long Man

Tian-Le Gao

Prospects for observing the missing <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2</mn><mi>D</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1</mn><mi>F</mi></math> charmonium states around 4 GeV

In all previous calculations of the nonlocal subleading contribution to the inclusive penguin decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">→</mo><msub><mi>X</mi><mi>s</mi></msub><mi>γ</mi></math> due to the interference of the electroweak operators <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi mathvariant="script">O</mi><mn>1</mn><mi>c</mi></msubsup><mo>−</mo><msub><mi mathvariant="script">O</mi><mrow><mn>7</mn><mi>γ</mi></mrow></msub></math> the local Voloshin term was subtracted. In view of the ongoing analysis at order <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>α</mi><mi>s</mi></msub></math>, we present a calculation of the complete nonlocal contribution which takes into account the high correlation between the uncertainties of the local Voloshin and the nonlocal term of the previous analyses. The new calculation has a high impact on the range of the nonlocal contribution.

Michael Benzke

Maria Vittoria Garzelli

Tobias Hurth

Addendum to “Resolved <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1</mn><mo>/</mo><msub><mi>m</mi><mi>b</mi></msub></math> contributions to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">→</mo><msub><mi>X</mi><mrow><mi>s</mi><mo>,</mo><mi>d</mi></mrow></msub><msup><mo>ℓ</mo><mo>+</mo></msup><msup><mo>ℓ</mo><mo>−</mo></msup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>B</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">→</mo><msub><mi>X</mi><mi>s</mi></msub><mi>γ</mi></math>”

Particle identification (PID) is essential for future particle physics experiments such as the Circular Electron-Positron Collider (CEPC) and the Future Circular Collider. A high-granularity Time Projection Chamber (TPC) not only provides precise tracking but also enables d$\textit{N}$/d$\textit{x}$ measurements for PID. The d$\textit{N}$/d$\textit{x}$ method estimates the number of primary ionization electrons, offering significant improvements in PID performance. However, accurate reconstruction remains a major challenge for this approach. In this paper, we introduce a deep learning model, the Graph Point Transformer (GraphPT), for d$\textit{N}$/d$\textit{x}$ reconstruction. In our approach, TPC data are represented as point clouds. The network backbone adopts a U-Net architecture built upon graph neural networks, incorporating an attention mechanism for node aggregation specifically optimized for point cloud processing. The proposed GraphPT model surpasses the traditional truncated mean method in PID performance. In particular, for the CEPC baseline TPC, the $\textit{K/π}$ separation power improves by approximately 10% to 20% in the momentum interval from 5 to 20 GeV/$\textit{c}$.

Guang Zhao

Yue Chang

Jinxian Zhang

Linghui Wu

Huirong Qi

Xin She

Mingyi Dong

Shengsen Sun

Jianchun Wang

Yifang Wang

Chunxu Yu

d$\textit{N}$/d$\textit{x}$ reconstruction with deep learning for high-granularity TPCs

We derive the general form of the effective equations governing black hole dynamics in the limit of a large number of dimensions $\textit{D}$. These split into a universal $\textit{soap-bubble}$ embedding condition for stationary configurations and a set of nonlinear dynamical evolution equations describing near-horizon fluctuations of $\textit{O}$(1/$\textit{D}$) amplitude over horizon scales of $$ O\left(1/\sqrt{D}\right) $$ . We obtain these equations in full generality, including arbitrary asymptotic sources in the near-horizon region, and we show that they form a parabolic system with a well-posed initial value problem. To connect the various approaches to large-$\textit{D}$ black hole dynamics, we also show that both the embedding and dynamical equations can be derived from the covariant membrane formalism. We clarify the intrinsic scope of the large-$\textit{D}$ approach, emphasizing that it yields a well-posed dynamical evolution only on horizon scales of $$ O\left(1/\sqrt{D}\right) $$ , which is the range where the most relevant horizon dynamics occur. Our results highlight the versatility of these effective theories for studying a wide class of black hole phenomena.

Roberto Emparan

Jordi Rafecas-Ventosa

Benson Way

General effective theories of black holes in the large $\textit{D}$ limit