Nuclear Theory·nucl-th

Tuesday·March 18, 2025

17 papers—8 primary·9 cross-listed

09
Testing the QCD formation time with reconstructed parton splittings
Jasmine Brewer🇬🇧 · Wilke van der Schee🇨🇭 · Urs Wiedemann🇨🇭
In high-energy elementary collisions the space-time ordering of parton branching processes is not accessible experimentally. In contrast, in heavy-ion collisions, parton showers interact with a spatially extended dense medium. This sets a reference length scale with respect to which the space-time ordering may be analysed. Here, we explore the possibility of identifying experimental signatures of the QCD formation time, $τ_{f}$ , on the level of a single parton splitting. Since heavy flavour offers an additional handle on tracing the propagation of individual quarks through the medium, we focus on the $g \to c c ˉ$ splitting. Combining adapted versions of the Cambridge-Aachen and FlavourCone jet finding algorithms with grooming techniques, we show how the kinematics of such splittings can be reconstructed with high fidelity using either final state partons or hadrons, and how the formation time distribution of parton splittings can be constructed therefrom. Medium modification leads to a characteristic modification of this $τ_{f}$ distribution. This effect can be used to construct experimentally-accessible ratios of $τ_{f}$ distributions, in which the sensitivity of the medium modification to the QCD formation time becomes measurable.
↳ hep-phnucl-exnucl-th5 citations
10
NNPDFpol2.0: a global determination of polarised PDFs and their uncertainties at next-to-next-to-leading order
Juan Cruz-Martinez🇨🇭 · Toon Hasenack🇳🇱 · Felix Hekhorn🇫🇮 · Giacomo Magni🇳🇱 · Emanuele R. Nocera🇮🇹 · Tanjona R. Rabemananjara🇳🇱 · Juan Rojo🇳🇱 · Tanishq Sharma🇮🇹 · Gijs van Seeventer🇳🇱
We present NNPDFpol2.0, a new set of collinear helicity parton distribution functions (PDFs) of the proton based on legacy measurements of structure functions in inclusive neutral-current longitudinally polarised deep-inelastic scattering (DIS), and of W -boson, single-inclusive, and di-jet production asymmetries in longitudinally polarised proton-proton collisions. The determination is accurate to next-to-next-to-leading order in the strong coupling, and includes heavy quark mass corrections in the analysis of DIS data. Uncertainties due to missing higher-order corrections are systematically incorporated by means of a covariance matrix determined by scale variations. NNPDFpol2.0 is based on a machine learning methodology, that makes use of Monte Carlo sampling for the representation of uncertainties into PDFs, of a neural network for the parametrisation of PDFs, of stochastic gradient descent for the optimisation of PDF parameters, and of hyperoptimisation for the selection of the best fitting model. We study the impact on PDFs of higher-order corrections, of the positivity constraint, and of the data. We demonstrate two phenomenological applications of NNPDFpol2.0, specifically the determination of the proton spin fraction carried by gluons and quarks, and of theoretical predictions for single-hadron production in longitudinally polarised DIS and proton-proton collisions.
↳ hep-phhep-exnucl-exnucl-thJHEP(2025)·37 citations
11
The $ϕN N, J / ψ N N, η_{c} N N$ systems based on HAL QCD interactions
Liang-Zhen Wen🇨🇳 · Yao Ma🇨🇳 · Lu Meng🇩🇪 · Shi-Lin Zhu🇨🇳
We investigate the existence of bound states and resonances in the $ϕN N, J / ψ N N, η_{c} N N$ systems using HAL QCD interactions for $ϕN, J / ψ N$ , and $η_{c} N$ . We employ the Gaussian expansion method to solve the complex-scaled Schrödinger equation and find no resonances or bound states in the $J / ψ N N$ and $η_{c} N N$ systems. We estimate the interaction between charmonium and nuclei, concluding that the $J / ψ$ or $η_{c}$ is likely to bind with $^{3} H$ , $^{3} He$ , $^{4} He$ , and heavier nuclei. For the $ϕN N$ system, the lattice QCD $ϕN (^{2} S_{1/2})$ interaction is absent. We combine the $ϕp$ correlation function analysis and HAL QCD results in Model A. We assume the spin-spin interactions for $J / ψ N$ and $ϕN$ systems are inversely proportional to their masses in Model B. Model A predicts a stronger $ϕN (^{2} S_{1/2})$ interaction and permits a two-body bound state, whereas Model B suggests the interaction is attractive but too weak to form a bound state. Both models predict bound states for the $I (J^{P}) = 0 (0^{-})$ and $0 (1^{-})$ $ϕN N$ systems. In Model A, these states are deeply bound with binding energies exceeding 15 MeV and remain existent when considering parameter uncertainties. In contrast, these states are very loosely bound in Model B, with binding energies below 1 MeV and an existent probability of about 60\% when parameter uncertainties are considered. In both models, there exist very loosely bound $I (J^{P}) = 0 (2^{-})$ three-body states which resemble a $ϕ$ -d atom with the $ϕ$ meson surrounding the deuteron, but their existences are sensitive to parameter uncertainties. No bound states or resonances are found in the isovector $I (J^{P}) = 1 (1^{-})$ $ϕN N$ system.
↳ hep-phhep-exhep-latnucl-ex+1PRD(2025)·13 citations
12
Tomography of the Rho meson in the QCD Instanton Vacuum: Transverse Momentum Dependent Parton Distribution Functions
Wei-Yang Liu🇺🇸 · Ismail Zahed🇺🇸
We analyse the rho meson unpolarized and polarized transverse momentum dependent parton distribution functions (TMDPDFs) in the instanton liquid model (ILM). The corresponding TMDs in ILM are approximated by a constituent quark beam function in the leading Fock state multiplied by a rapidity-dependent factor resulting from the staple-shaped Wilson lines, for fixed longitudinal momentum, transverse separation, and rapidity. At the resolution of the ILM, all of the rho meson TMDs are symmetric in parton x for fixed transverse momentum, and Gaussian-like in the transverse momentum for fixed parton x. The latter is a direct consequence of the profiling of the quark zero modes in the ILM. The evolved TMDs at higher rapidity using the Collins-Soper kernel, and higher resolution using the renormalization group (RG), show substantial skewness towards low parton x.
↳ hep-phhep-lathep-thnucl-thPRD(2025)·8 citations
13
The Science of the Einstein Telescope
Adrian Abac · Raul Abramo · Simone Albanesi · Angelica Albertini · Alessandro Agapito · Michalis Agathos · Conrado Albertus · Nils Andersson · Tomas Andrade · Igor Andreoni · Federico Angeloni · Marco Antonelli and 476 other authors
Einstein Telescope (ET) is the European project for a gravitational-wave (GW) observatory of third-generation. In this paper we present a comprehensive discussion of its science objectives, providing state-of-the-art predictions for the capabilities of ET in both geometries currently under consideration, a single-site triangular configuration or two L-shaped detectors. We discuss the impact that ET will have on domains as broad and diverse as fundamental physics, cosmology, early Universe, astrophysics of compact objects, physics of matter in extreme conditions, and dynamics of stellar collapse. We discuss how the study of extreme astrophysical events will be enhanced by multi-messenger observations. We highlight the ET synergies with ground-based and space-borne GW observatories, including multi-band investigations of the same sources, improved parameter estimation, and complementary information on astrophysical or cosmological mechanisms obtained combining observations from different frequency bands. We present advancements in waveform modeling dedicated to third-generation observatories, along with open tools developed within the ET Collaboration for assessing the scientific potentials of different detector configurations. We finally discuss the data analysis challenges posed by third-generation observatories, which will enable access to large populations of sources and provide unprecedented precision.
↳ gr-qcastro-ph.COastro-ph.HEastro-ph.IM+1JCAP(2026)·506 citations
14
Axion-Like Particle Mediated Dark Matter and Neutron Star Properties in the QHD Model
Tanech Klangburam🇹🇭 · Chakrit Pongkitivanichkul🇹🇭
We investigate the effects of the ALP-mediated dark matter (DM) model on neutron star properties using the Quantum Hadrodynamics model (QHD). Using the relativistic mean-field approximation with the QHD-ALP-DM framework, we compute the equation of state (EoS) of neutron stars. Based on our previous study, we find that typical ALP parameter values have no significant effect on the EoS. We then explore various parametrizations of this model by varying the DM Fermi momentum, $q_{f}$ , and DM mass, $m_{χ}$ . Our results show that increasing $q_{f}$ or $m_{χ}$ shifts the energy density to higher values while reducing the maximum mass, radius, and tidal deformability of neutron stars. Finally, comparison with observational constraints from gravitational wave events and pulsar measurements indicates that the allowed parameter space for this model is constrained to $q_{f} < 0.05$ GeV and $m_{χ} < 1000$ GeV. As a result, our study highlights the importance of next-generation gamma-ray observatories, such as the Cherenkov Telescope Array (CTA), in probing the ALP-mediated DM model.
↳ astro-ph.HEhep-phnucl-thPRD(2025)·4 citations
15
Gluon gravitational form factors of the proton in a light-front spectator model
Amrita Sain🇨🇳 · Poonam Choudhary🇮🇳 · Bheemsehan Gurjar🇮🇳 · Chandan Mondal🇨🇳 · Dipankar Chakrabarti🇮🇳 · Asmita Mukherjee🇮🇳
We calculate the gluon gravitational form factors (GFFs) of the proton using a light-front spectator model based on soft-wall AdS/QCD, where the active parton is a gluon. The model parameters are determined by fitting the unpolarized gluon distribution function to the NNPDF3.0nlo dataset. Subsequently, we predict the polarized gluon distribution, finding consistency with global analyses. Our predictions for the gluon GFFs show good agreement with recent lattice QCD simulations and experimental extractions. Using these gluon GFFs, we compute the contribution of the gluon to the proton mass and mechanical radii. We also analyze the gluonic contribution to the two-dimensional Galilean densities, including energy density, radial and tangential pressure, isotropic pressure, and pressure anisotropy of the proton.
↳ hep-phhep-lathep-thnucl-thPRD(2025)·20 citations
16
A multi-messenger mass determination method for LISA Neutron-Star White-Dwarf Binaries
Kaye Jiale Li · Jane SiNan Long · Kinwah Wu · Albert K. H. Kong
Determining the mass of the neutron stars (NSs) accurately improves our understanding of the NS interior and complicated binary evolution. However, the masses of the systems are degenerate with orbital inclination angle when using solely gravitational waves (GWs) or electromagnetic measurements, especially for face-on binaries. Taking advantages of both GWs and optical observations for LISA neutron-star white-dwarf (NS-WD) binaries, we propose a mass determination method utilising multi-messenger observational information. By combining the binary mass function obtained from optical observations and a GW mass function, that we introduce, derived from GW observations, we demonstrate how we can set improved constraints on the NS mass and break the degeneracy in the mass and viewing inclination determination. We further comment on the universal relation of the error bar of the GW mass function versus GW signal-to-noise ratio (SNR), and propose a simple method for the estimate of capability of GW observations on mass determination with {LISA}. We show that for ultra-compact NS-WD binaries within our Galaxy, the mass of the NS can be constrained to within an accuracy of +- 0.2 \solarmass with the proposed method.
↳ astro-ph.HEnucl-thApJ(2025)·2 citations
17
Radiative corrections on vortical spin polarization in hot QCD matter
Shuo Fang🇨🇳 · Shi Pu🇨🇳 · Di-Lun Yang🇹🇼
We investigate the radiative corrections on spin polarization of relativistic fermions induced by vortical fields in thermal-equilibrium QCD matter at weak coupling. Such corrections stem from the self-energy gradients in quantum kinetic theory, which are further obtained by a more systematic and general approach through the Keldysh equation. By applying the hard-thermal-loop approximation, we obtain new corrections upon the spin-polarization spectrum and also the axial-charge current in connection to the axial/chiral vortical effect for massive quarks up to the leading order of the QCD coupling. Further influence on spin alignment of vector mesons from similar effects is also analyzed.
↳ hep-phhep-thnucl-thPRD(2025)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE