Fri·Oct 18, 2024Friday·October 18, 2024

1. 01*

   Sketching pion and proton mass distributions

   Xiaobin Wang🇨🇳 · Zanbin Xing🇨🇳 · Lei Chang🇨🇳 · Minghui Ding🇨🇳 · Khépani Raya🇪🇸 · Craig D. Roberts🇨🇳

   A light-front holographic model is used to illustrate an algebraic scheme for constructing a representation of a hadron's zero-skewness generalised parton distribution (GPD) from its valence-quark distribution function (DF) and electromagnetic form factor, $F_H$, without reference to deeply virtual Compton scattering data. The hadron's mass distribution gravitational form factor, $A_H$, calculated from this GPD is harder than $F_H$; and, for each hadron, the associated mass-density profile is more compact than the analogous charge profile, with each pion near-core density being larger than that of its proton partner. These features are independent of the scheme employed.

   ↳ hep-phhep-exhep-latnucl-ex+1PLB(2025)·13 citations
2. 02*

   An end-to-end generative diffusion model for heavy-ion collisions

   Jing-An Sun🇨🇳 · Li Yan🇨🇳 · Charles Gale🇨🇦 · Sangyong Jeon🇨🇦

   We train a generative diffusion model (DM) to simulate ultra-relativistic heavy-ion collisions from end to end. The model takes initial entropy density profiles as input and produces two-dimensional final particle spectra, successfully reproducing integrated and differential observables. It also captures higher-order fluctuations and correlations. These findings suggest that the generative model has successfully learned the complex relationship between initial conditions and final particle spectra for various shear viscosities, as well as the fluctuations introduced during initial entropy production and hadronization stages, providing an efficient framework for resource-intensive physical goals. The code and trained model are available at https://huggingface.co/Jing-An/DiffHIC/tree/main.

   ↳ nucl-thhep-phnucl-exPRC(2025)·10 citations
3. 03*

   Azimuthal Correlation Anisotropies in p + p Collisions Simulated by Pythia

   Manuel Sebastian Torres🇨🇴 · Yicheng Feng🇺🇸 · Fuqiang Wang🇺🇸

   Stimulated by the keen interest of possible collective behavior in high-energy proton-proton and proton-nucleus collisions, we study two-particle angular correlations in pseudorapidity and azimuthal differences in simulated p + p interactions by the Pythia 8 event generator. Multi-parton interactions and color connection are included in these simulations which have been perceived to produce collectivity in final-state particles. Meanwhile, contributions from genuine few-body nonflow correlations, not of collective flow behavior, are known to be severe in those small-system collisions. We present our Pythia correlation studies in a pedagogical way and report azimuthal harmonic anisotropies analyzed by several methods. We observe anisotropies in those Pythia simulated events qualitatively and semi-quantitatively similar to experimental data. Our findings highlight the delicate nature of azimuthal anisotropies in small-system collisions, and provide a benchmark helping improve data analysis and interpret experimental measurements in small-system collisions.

   ↳ nucl-thnucl-exCPC(2025)·1 citation
4. 04*

   Twist-3 contribution in the Drell-Yan process with tensor-polarized deuteron

   Si-Yi Qiao🇨🇳 · Qin-Tao Song🇨🇳

   The tensor-polarized structures of the deuteron can be probed through the proton-deuteron Drell-Yan process, where the proton is unpolarized and the deuteron is tensor polarized. This measurement will be conducted at Fermilab in the near future. In this reaction, the twist-3 contribution is not negligible compared to the twist-2 contribution due to the limited invariant mass of the dilepton pair. We calculate the twist-3 contribution for the Drell-Yan cross section with a tensor-polarized deuteron target, preserving the U(1)-gauge invariance of the hadronic tensor. The cross sections and weighted cross sections are expressed in terms of the tensor-polarized parton distribution functions (PDFs), thus one can extract the PDFs $f_{1LL}$, $f_{LT}$, and $f_{1LT}^{(1)}$ from the experimental measurements of Drell-Yan process. Our study should be helpful to solve the puzzle in the tensor-polarized structures of the deuteron.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2025)·4 citations
5. 05*

   Negative moments as the signature of the radial density at small distances

   M. Atoui🇫🇷 · M. Hoballah🇫🇷 · M. Lassaut🇫🇷 · J. Van de Wiele🇫🇷

   The present paper proposes a robust evaluation of any radial density at small distances using negative-order radial moments evaluated in momentum space. This evaluation provides a valuable insight into the behavior of a given radial density in the vicinity of $r=0$, and puts strong emphasis on the importance of measuring form factors at large squared four-momentum transfer, a domain essential for the determination of negative order moments. A specific attention is paid to the regularization scheme directly affecting the numerical determination of the radial density's parametrization. The proposed method is applied to non-relativistic study cases of the nucleon electric ($G_{En},G_{Ep}$), and proton magnetic $G_{Mp}$ form factors. The validation is performed through comparison of the results of the approach to the analytically determined Maclaurin expansion - in the vicinity of $r=0$ - of the radial density function. The method is also applied to the relativistic Dirac form factor $F_1$ of the proton. In such a non-trivial case, the Maclaurin development might not exist for the radial density, rendering the determination from the proposed method extremely important.

   ↳ nucl-thnucl-exEPJA(2025)·0 citations
6. 06*

   Heavy-light Pseudoscalar Mesons: Light-Front Wave Functions and Generalized Parton Distributions

   B. Almeida-Zamora🇲🇽 · J.J. Cobos-Martínez🇲🇽 · A. Bashir🇲🇽 · K. Raya🇪🇸 · J. Rodríguez-Quintero🇪🇸 · J. Segovia🇪🇸

   The internal structure of the lowest-lying pseudo-scalar mesons with heavy-light quark content is thoroughly studied using an algebraic model that has been successfully applied to similar physical observables of pseudoscalar and vector mesons with hidden-flavor quark content, ranging from light to heavy quark sectors. This model is based on constructing simple and evidence-based ansätze for the mesons' Bethe-Salpeter amplitude (BSA) and quark propagator, allowing the Bethe-Salpeter wave function (BSWF) to be computed algebraically. Its projection onto the light front yields the corresponding light-front wave function (LFWF), which provides easy access to the valence-quark Parton Distribution Amplitude (PDA) by integrating over the transverse momentum squared. We leverage our current knowledge of the PDAs of the lowest-lying pseudo-scalar heavy-light mesons to compute their Generalized Parton Distributions (GPDs) via the overlap representation of the LFWFs. From this three-dimensional information, various limits and projections allow us to deduce the related Parton Distribution Functions (PDFs), Electromagnetic Form Factors (EFFs), and Impact Parameter Space GPDs (IPS-GPDs). Whenever possible, we make explicit comparisons with available experimental results and previous theoretical predictions.

   ↳ hep-phhep-exhep-latnucl-ex+1PoS(2025)·1 citation
7. 07*

   Observation of a rare beta decay of the charmed baryon with a Graph Neural Network

   BESIII Collaboration: M. Ablikim · M. N. Achasov · P. Adlarson · O. Afedulidis · X. C. Ai · R. Aliberti · A. Amoroso · Q. An · Y. Bai · O. Bakina · I. Balossino · Y. Ban and 649 other authors

   The beta decay of the lightest charmed baryon ${\Lambda }_c^{+}$ provides unique insights into the fundamental mechanism of strong and electro-weak interactions, serving as a testbed for investigating non-perturbative quantum chromodynamics and constraining the Cabibbo-Kobayashi-Maskawa (CKM) matrix parameters. This article presents the first observation of the Cabibbo-suppressed decay ${\Lambda }_c^{+}\to n{e}^{+}{\nu }_e$, utilizing $4.5{\mathrm{fb}}^{-1}$ of electron-positron annihilation data collected with the BESIII detector. A novel Graph Neural Network based technique effectively separates signals from dominant backgrounds, notably ${\Lambda }_c^{+}\to \Lambda e^{+}{\nu }_e$, achieving a statistical significance exceeding $10\sigma$. The absolute branching fraction is measured to be $(3.57\pm 0.34_{stat.}\pm 0.14_{syst.})\times 10^{-3}$. For the first time, the CKM matrix element $\left|V_{cd}\right|$ is extracted via a charmed baryon decay as $0.208\pm 0.011_{exp.}\pm 0.007_{\mathrm{LQCD}}\pm 0.001_{{\tau }_{{\Lambda }_c^{+}}}$. This work highlights a new approach to further understand fundamental interactions in the charmed baryon sector, and showcases the power of modern machine learning techniques in experimental high-energy physics.

   ↳ hep-exhep-lathep-phnucl-exNature Commun.(2025)·23 citations
8. 08*

   Azimuthal modulation in light-by-light scattering from ultraperipheral collisions at LHC

   Yu Jia🇨🇳 · Shuo Lin🇨🇳 · Jian Zhou🇨🇳 · Ya-jin Zhou🇨🇳

   Elastic light-by-light(LbL) scattering, one of the most fascinating processes in the Standard Model(SM), has recently been observed in the ultraperipheral collisions(UPCs) of relativistic heavy ions in the Atlas and CMS experiments at the Large Hadron Collider LHC. Recognizing that the incident quasi-real photons in LbL scattering are strongly linearly polarized, we re-investigate the LbL scattering in UPCs by incorporating the joint dependence of the impact parameter and transverse momenta of the incident photons. We show that the linear polarization of incident photons generates a sizable $\cos 2\varphi$-type azimuthal modulation, which awaits the test in future LHC and EIC experiments.

   ↳ hep-phhep-exnucl-exnucl-th4 citations
9. 09*

   Neutron-neutron distribution of the triton from pionless EFT

   Tanja Kirchner🇩🇪 · Matthias Göbel🇮🇹 · Hans-Werner Hammer🇩🇪

   We compute the neutron-neutron relative-energy distribution of the triton following the hard knockout of the proton in pionless effective field theory. This distribution can be used to study universality as well as to obtain information on the neutron-neutron interaction. Especially, one can infer the scattering length from fitting theory predictions for the shape of the distribution to experimental data. To obtain the distribution for the triton, we first solve the ground-state three-body problem using momentum-space Faddeev equations. Next, we include the neutron-neutron final-state interaction by applying the corresponding Møller operator to the ground state. We present leading-order (LO) and next-to-leading order (NLO) pionless effective field theory results with quantified uncertainties. At NLO, we include the effective ranges semi-perturbatively. We conclude, that pionless EFT works reliably as expected and that the neutron-neutron distribution of the triton shows a significant sensitivity to the scattering length.

   ↳ nucl-thnucl-exPRC(2025)·1 citation

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.