We report the first global extraction of generalized parton distributions, GUMP 1.0, by combining deeply virtual Compton scattering and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>ρ</mi></mrow></math>-meson production data from Jefferson Lab and the Hadron-Electron Ring Accelerator with global fits of parton distribution functions, charge form factors, and lattice quantum chromodynamics simulations. Using a conformal moment space parametrization, we achieve a unified description across low- and high-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>x</mi></math> regions at next to leading order accuracy in perturbative corrections. The results provide state-of-the-art generalized parton distributions consistent with almost all known facts, enabling three-dimensional nucleon imaging in impact parameter space and, at the same time, establishing a benchmark for future theoretical and experimental studies of the nucleon structure.

United States

Yuxun Guo

Fatma P. Aslan

Xiangdong Ji

M. Gabriel Santiago

First Global Extraction of Generalized Parton Distributions from Experiment and Lattice Data with Next-to-Leading-Order Accuracy

Light cone distribution amplitudes for a light baryon can be extracted through the simulation of the quasi-distribution amplitudes (quasi-DAs) on the lattice. We implement the hybrid renormalization for the quasi-DAs of light baryons. Lattice simulations are performed using <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>N</mi><mi>f</mi></msub><mo>=</mo><mn>2</mn><mo>+</mo><mn>1</mn></math> stout-smeared clover fermions and a tree-level Symanzik-improved gauge action, with three lattice spacings of 0.105, 0.077, 0.052 fm. By analyzing zero-momentum matrix elements for different lattice spacings, we extract the linear divergence associated with the Wilson-line self-energy. Matching to perturbative matrix elements in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>MS</mi><mo stretchy="true">¯</mo></mover></math> scheme yields the residual self-renormalization factors. Using these factors, we renormalize the quasi-DAs within the hybrid scheme, which combines self-renormalization at large separations and the ratio scheme at short distances. The renormalized results demonstrate effective cancellation of linear divergences and yield smooth, continuumlike coordinate-space distributions suitable for subsequent Fourier transformation and perturbative matching. These results establish the viability of both self- and hybrid-renormalization frameworks for light baryon quasi-DAs, providing a robust foundation for LaMET-based determinations of light cone distribution amplitudes in future.

China

Haoyang Bai

Jun Hua

Xiangyu Jiang

Jian Liang

Germany

Andreas Schäfer

Wei Wang

Yi-Bo Yang

Jian-Hui Zhang

JiaLu Zhang

Mu-Hua Zhang

Qi-An Zhang

Hybrid renormalization for distribution amplitude of a light baryon in large momentum effective theory

We present a search for light dark matter particles through their interactions with atomic electrons and nucleons, utilizing PandaX-4T data with an effective exposure of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>1.04</mn><mtext> </mtext><mtext> </mtext><mi>tonne</mi><mo>·</mo><mi>year</mi></mrow></math> for ionization-only data and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>1.20</mn><mtext> </mtext><mtext> </mtext><mi>tonne</mi><mo>·</mo><mi>year</mi></mrow></math> for paired data. Our analysis focuses on the energy range (efficiency <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>&gt;</mo><mn>0.01</mn></math>) of approximately 0.33 to 3 keV for nuclear recoils and from 0.04 to 0.39 keV for electronic recoils. We establish the most stringent constraints on spin-independent dark matter-nucleon interactions within a mass range of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>2.5</mn><mi>–</mi><mn>5.0</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi><mo>/</mo><msup><mrow><mi>c</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math>, spin-dependent neutron-only interactions within <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>1.0</mn><mi>–</mi><mn>5.6</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi><mo>/</mo><msup><mrow><mi>c</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math>, and spin-dependent proton-only interactions within <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>1.0</mn><mi>–</mi><mn>4.1</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi><mo>/</mo><msup><mrow><mi>c</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math>. Their corresponding limits at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>3</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi><mo>/</mo><msup><mrow><mi>c</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math> are <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1.1</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>43</mn></mrow></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>8.4</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>40</mn></mrow></msup></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>2.8</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>38</mn></mrow></msup><mtext> </mtext><mtext> </mtext><msup><mrow><mi>cm</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math>, respectively. Additionally, our results improve the upper limits on the dark matter-electron scattering cross section by a factor of 1.5 and 9.3 for heavy and light mediator scenarios, respectively, within <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>50</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi><mo>/</mo><msup><mi>c</mi><mn>2</mn></msup></math> to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>10</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi><mo>/</mo><msup><mi>c</mi><mn>2</mn></msup></math>, compared with previous best results. The improved limits reach <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1.5</mn><mo>×</mo><mrow><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>41</mn></mrow></msup></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>5.6</mn><mo>×</mo><mrow><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>37</mn></mrow></msup><mtext> </mtext><mtext> </mtext><msup><mrow><mi>cm</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></mrow></math> at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>200</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi><mo>/</mo><msup><mi>c</mi><mn>2</mn></msup></math> for the heavy and light mediators, respectively.

Minzhen Zhang

Zihao Bo

Wei Chen

Xun Chen

Yunhua Chen

Chen Cheng

Xiangyi Cui

Manna Deng

Yingjie Fan

Deqing Fang

Xuanye Fu

Zhixing Gao

Yujie Ge

Lisheng Geng

Karl Giboni

Xunan Guo

Xuyuan Guo

Zichao Guo

Chencheng Han

Ke Han

Changda He

Jinrong He

Houqi Huang

Junting Huang

Yule Huang

Ruquan Hou

Yonglin Ju

Xiaorun Lan

Chenxiang Li

Jiafu Li

Mingchuan Li

Peiyuan Li

Shuaijie Li

Tao Li

Yangdong Li

Zhiyuan Li

Qing Lin

Jianglai Liu

Yuanchun Liu

Congcong Lu

Xiaoying Lu

Lingyin Luo

Yunyang Luo

Yugang Ma

Yajun Mao

Yue Meng

Binyu Pang

Ningchun Qi

Zhicheng Qian

Xiangxiang Ren

Dong Shan

Xiaofeng Shang

Xiyuan Shao

Guofang Shen

Manbin Shen

Wenliang Sun

Xuyan Sun

Yi Tao

Yueqiang Tian

Yuxin Tian

Anqing Wang

Guanbo Wang

Hao Wang

Haoyu Wang

Jiamin Wang

Lei Wang

Meng Wang

Qiuhong Wang

Shaobo Wang

Shibo Wang

Siguang Wang

Xu Wang

Zhou Wang

Yuehuan Wei

Weihao Wu

Yuan Wu

Mengjiao Xiao

Xiang Xiao

Kaizhi Xiong

Jianqin Xu

Yifan Xu

Shunyu Yao

Binbin Yan

Xiyu Yan

Yong Yang

Peihua Ye

Chunxu Yu

Ying Yuan

Zhe Yuan

Youhui Yun

Xinning Zeng

Peng Zhang

Shibo Zhang

Siyuan Zhang

Shu Zhang

Tao Zhang

Wei Zhang

Yang Zhang

Search for Light Dark Matter with 259 Days of Data in PandaX-4T

We phenomenologically constrain the small-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>x</mi></math> and small-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ξ</mi></math> gluon generalized parton distributions (GPDs) with the deeply virtual <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> production (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>DV</mi><mi>J</mi><mo>/</mo><mi>ψ</mi><mi mathvariant="normal">P</mi></mrow></math>) in the framework of GPDs through universal moment parameterization (GUMP). We use a hybrid cross-section formula combining collinear factorization to the next-to-leading order (NLO) accuracy of the strong coupling <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>α</mi><mi>s</mi></msub></math>, with corrections from nonrelativistic QCD to account for the power corrections due to the heavy <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> mass. We reach reasonable fit to the measured differential cross sections of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>DV</mi><mi>J</mi><mo>/</mo><mi>ψ</mi><mi mathvariant="normal">P</mi></mrow></math> by H1 at the Hadron-Electron Ring Accelerator as well as forward gluon parton distribution functions (PDFs) from JAM22 global analysis. We find that both NLO and nonrelativistic corrections are significant for heavy vector meson productions. Of course, the gluon GPD we obtain still contains considerable freedom in need of inputs from other constraints, particularly in the distribution-amplitude-like region.

Jinghong Yang

Hao-Cheng Zhang

Small-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>x</mi></math> gluon GPD constrained from deeply virtual <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> production and gluon PDF through universal-moment parametrization

Light-cone distribution amplitudes (LCDAs) of heavy meson within heavy quark effective theory (HQET) are crucial for predicting physical observables in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi></math> decays, but unfortunately there is no first-principle result due to severe challenges. After analyzing these challenges, we propose a realistic method to determine heavy meson LCDA. We utilize equal-time correlations and incorporate a dynamic quark field for a fast moving heavy quark. To verify this method, we make use of lattice QCD simulation on a lattice ensemble with spacing <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>a</mi><mo>=</mo><mn>0.05187</mn><mtext> </mtext><mtext> </mtext><mi>fm</mi></math>. The preliminary findings for HQET LCDAs qualitatively align with phenomenological models, and the fitted result for the first inverse moment <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>λ</mi><mi>B</mi><mrow><mo>−</mo><mn>1</mn></mrow></msubsup></math> is consistent with the experimentally constrained region from <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><mi>γ</mi><mo>ℓ</mo><msub><mi>ν</mi><mo>ℓ</mo></msub></math>. We explore how our findings can reduce model uncertainties in predictions of heavy-to-light form factors at large recoil. These results demonstrate the promise of our method in providing first-principle predictions for heavy meson LCDAs.

Xue-Ying Han

Cai-Dian Lü

Ji Xu

Shuai Zhao

Realistic method to access heavy meson light-cone distribution amplitudes from first-principle

Detailed studies of two-neutrino double electron capture (2$\textit{ν}$DEC) is a crucial step towards searching for the neutrinoless mode to explore the Majorana nature of neutrinos. We have measured precisely the half-life of the 2$\textit{ν}$DEC process in Xe, utilizing a total exposure of 1.73 tonne year from the commissioning run and the first science run of the PandaX-4T experiment. A time-dependent background model in the $$ \mathcal{O} $$ (10 keV) energy is constructed for the first time in PandaX-4T data. With an unbinned maximum likelihood fit, we determine the half-life of the 2$\textit{ν}$DEC process to be (1.03 ± 0.15 ± 0.08 ) × 10 yr. Furthermore, we have evaluated the capture fraction for both electrons captured from the $\textit{K}$ shell ($\textit{KK}$) to be (65 ± 5)%, which aligns with the Xe nuclear model calculations within 1.8 $\textit{σ}$.

Zhaokan Cheng

Di Huang

Yu Hou

Xiangpan Ji

Wenbo Ma

Xuyang Ning

Xiuli Wang

Yingxin Zhang

Yuanyuan Zhang

Li Zhao

Jifang Zhou

Jiaxu Zhou

Jiayi Zhou

Ning Zhou

Xiaopeng Zhou

Yubo Zhou

Measurement of two-neutrino double electron capture half-life of

We perform a search of double beta decay of Xe to the excited state, $$ {0}_1^{+} $$ , of Ba (2$\textit{νββ}$- $$ {0}_1^{+} $$ ), using the dual-phase xenon detector of PandaX-4T with the first 94.9-day commissioning data. The multi-site events are reconstructed up to the MeV energy scale, which helps to improve the background model significantly. The background contribution from the stainless steel platform outside PandaX-4T cryostat is evaluated for the first time. No significant evidence for 2$\textit{νββ}$- $$ {0}_1^{+} $$ is observed, resulting in a lower limit on half-life of 7$\textit{.}$5 × 10 yr at the 90% confidence level. This is the first experimental limit on such a rare decay in a natural xenon-based detector.

Zhizhen Zhou

Search for double beta decay of

We present a novel constraint on light dark matter utilizing 1.54 metric ton/year of data acquired from the PandaX-4T dual-phase xenon time projection chamber. This constraint is derived through detecting electronic recoil signals resulting from the interaction with solar-enhanced dark matter flux. Low-mass dark matter particles, lighter than a few <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>MeV</mi><mo>/</mo><msup><mi>c</mi><mn>2</mn></msup></math>, can scatter with the thermal electrons in the Sun. Consequently, with higher kinetic energy, the boosted dark matter component becomes detectable via contact scattering with xenon electrons, resulting in a few keV energy deposition that exceeds the threshold of PandaX-4T. We calculate the expected recoil energy in PandaX-4T considering the Sun’s acceleration with heavy mediators and the detection capabilities of the xenon detector. The first experimental search results using the xenon detector yield the most stringent upper limits cross section of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>3.51</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>39</mn></mrow></msup><mtext> </mtext><mtext> </mtext><msup><mrow><mi>cm</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math> at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>0.08</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi><mo>/</mo><msup><mrow><mi>c</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math> for a solar boosted dark matter mass ranging from 0.02 to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>10</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi><mo>/</mo><msup><mi>c</mi><mn>2</mn></msup></mrow></math>, achieving a 23-fold improvement compared with earlier experimental studies.

Search for Solar Boosted Dark Matter Particles at the PandaX-4T Experiment

We report a search for a lepton-portal dark matter model, where dark matter couples to a charged lepton in the standard model. This simplified model naturally leads to photon-mediated dark matter interactions with nuclei, making it suitable for direct dark matter detection experiments. Matching to the framework of non-relativistic effective field theory for dark matter, we report the first sensitive search for this model using data from the PandaX-4T commissioning run. Our results yield strong constraints on Dirac fermion dark matter but relatively weaker constraints on Majorana dark matter due to the suppression of effective photon interactions. These constraints complement those obtained from the collider and indirect detection experiments.

Search for lepton portal dark matter in the PandaX-4T experiment

Parton distribution functions (PDFs) at large are challenging to extract from experimental data, yet they are essential for understanding hadron structure and searching for new physics beyond the Standard Model. Within the framework of the large momentum expansion of lattice quasi-PDFs, we investigate large PDFs, where the matching coefficient is factorized into the hard kernel, related to the active quark momentum , and the threshold soft function, associated with the spectator momentum (1 − ) . The renormalization group equation of the soft function enables the resummation of the threshold double logarithms ln (1 − ), which is crucial for a reliable and controllable calculation of large PDFs. Our analysis with pion valence PDFs indicates that perturbative matching breaks down when the spectator momentum (1 − ) approaches Λ , but remains valid when both and (1 − ) are much larger than Λ . Additionally, we incorporate leading renormalon resummation within the threshold framework, demonstrating good perturbative convergence in the region where both spectator and active quark momenta are perturbative scales.