Nuclear Theory·nucl-th

Thursday·May 9, 2024

12 papers—7 primary·5 cross-listed

08
Baryon-number -flavor separation in the topological expansion of QCD
David Frenklakh🇺🇸 · Dmitri Kharzeev🇺🇸 · Giancarlo Rossi🇮🇹 · Gabriele Veneziano🇨🇭
Gauge invariance of QCD dictates the presence of string junctions in the wave functions of baryons. In high-energy inclusive processes, these baryon junctions have been predicted to induce the separation of the flows of baryon number and flavor. In this paper we describe this phenomenon using the analog-gas model of multiparticle production proposed long time ago by Feynman and Wilson and adapted here to accommodate the topological expansion in QCD. In this framework, duality arguments suggest the existence of two degenerate junction-antijunction glueball Regge trajectories of opposite $C$ -parity with intercept close to 1/2. The corresponding results for the energy and rapidity dependence of baryon stopping are in reasonably good agreement with recent experimental findings from STAR and ALICE experiments. We show that accounting for correlations between the fragmenting strings further improves agreement with the data, and outline additional experimental tests of our picture at the existing (RHIC, LHC, JLab) and future (EIC) facilities.
↳ hep-phhep-thnucl-thJHEP(2024)·8 citations
09
Onset of scaling violation in pion and kaon elastic electromagnetic form factors
Zhao-Qian Yao🇮🇹 · Daniele Binosi🇮🇹 · Craig D. Roberts🇨🇳
Using a symmetry-preserving truncation of the quantum field equations describing hadron properties, parameter-free predictions are delivered for pion and kaon elastic electromagnetic form factors, $F_{P = π, K}$ , thereby unifying them with kindred results for nucleon elastic electromagnetic form factors. Regarding positive-charge states, the analysis stresses that the presence of scaling violations in QCD entails that $Q^{2} F_{P} (Q^{2})$ should exhibit a single maximum on $Q^{2} > 0$ . Locating such a maximum is both necessary and sufficient to establish the existence of scaling violations. The study predicts that, for charged $π$ , $K$ mesons, the $Q^{2} F_{P} (Q^{2})$ maximum lies in the neighbourhood $Q^{2} ≃ 5$ GeV $^{2}$ . Foreseeable experiments will test these predictions and, providing their $Q^{2}$ reach meets expectations, potentially also provide details on the momentum dependence of meson form factor scaling violation.
↳ hep-phhep-exhep-latnucl-ex+1PLB(2024)·25 citations
10
Amplitude analysis of $B^{0} \to K_{S}^{0} K^{+} K^{-}$ decays in a quasi-two-body QCD factorization approach
J.-P. Dedonder🇫🇷 · R. Kamiński🇵🇱 · L. Leśniak🇵🇱 · B. Loiseau🇫🇷 · P. Żenczykowski🇵🇱
The $B^{0} \to K_{S}^{0} K^{+} K^{-}$ decay amplitude is derived within a quasi-two-body QCD factorization framework in terms of kaon form factors and $B^{0}$ to two-kaon-transition functions. The final state kaon-kaon interactions in the $S$ , $P$ , and $D$ waves are taken into account. The unitarity constraints are satisfied for the two kaons in scalar states. It is shown that with few terms of the full decay amplitude one may reach a fair agreement with the total branching fraction and Dalitz-plot projections published in 2010 by the Belle Collaboration and in 2012 by the $BABAR$ Collaboration. With 13 free parameters, our model fits the corresponding 422 data with a $χ^{2}$ of 583.6 which leads to a $χ^{2}$ per degree of freedom equal to 1.43. The dominant branching fraction arises from the $f_{0} (K^{+} K^{-}) K_{S}^{0}$ mode with 83.0 $%$ of the total branching. The next important mode is dominated by $ϕ K_{S}^{0}$ plus small $ω K_{S}^{0}$ and $ρ^{0} K_{S}^{0}$ modes with 18.3 $%$ of the total. Then follows the $a_{0}^{\pm} K^{\mp}$ mode with 6.2 $%$ . Adding the other smaller modes, the total percentage sum is 107.7 $%$ which indicates a small interference contribution. In most regions of the Dalitz plot, our model gives rather small $C P$ asymmetry, but in some parts its values can be large and positive or negative. Its predicted total value is equal to -0.11 $%$ . The calculated time dependent $CP$ -asymmetry parameters agree, within errors, with those obtained by the $BABAR$ analysis. Our model amplitude can be the basis for a parametrization in experimental Dalitz plot analyses of LHCb and Belle II Collaborations.
↳ hep-phnucl-thPRD(2024)·1 citation
11
Longitudinal spin polarization in a thermal model with dissipative corrections
Soham Banerjee🇮🇳 · Samapan Bhadury🇵🇱 · Wojciech Florkowski🇵🇱 · Amaresh Jaiswal🇮🇳 · Radoslaw Ryblewski🇵🇱
In this work, we address the problem of longitudinal spin polarization of the $Λ$ hyperons produced in relativistic heavy-ion collisions. We combine a relativistic kinetic-theory framework that includes spin degrees of freedom treated in a classical way with the freeze-out parametrization used in previous investigations. The use of the kinetic theory allows us to incorporate dissipative corrections (due to the thermal shear and gradients of thermal vorticity) into the Pauli-Lubanski vector that determines spin polarization and can be directly compared with the experimental data. As in earlier similar studies, it turns out that a successful description of data can only be achieved with additional assumptions -- in our case, they involve the use of projected thermal vorticity and a suitably adjusted time for spin relaxation ( $τ_{s}$ ). From our analysis, we find that $τ_{s} \sim 5$ fm/ $c$ , which is comparable with other estimates.
↳ hep-phhep-thnucl-thPRC(2025)·24 citations
12
The Ghent Hybrid Model in NuWro: a new neutrino single-pion production model in the GeV regime
Qiyu Yan🇨🇳 · Kajetan Niewczas🇧🇪 · Alexis Nikolakopoulos🇧🇪 · Raúl González-Jiménez🇪🇸 · Natalie Jachowicz🇧🇪 · Xianguo Lu🇬🇧 · Jan Sobczyk🇵🇱 · Yangheng Zheng🇨🇳
Neutrino-induced single-pion production constitutes an essential interaction channel in modern neutrino oscillation experiments, with its products building up a significant fraction of the observable hadronic final states. Frameworks of oscillation analyses strongly rely on Monte Carlo neutrino event generators, which provide theoretical predictions of neutrino interactions on nuclear targets. Thus, it is crucial to integrate state-of-the-art single-pion production models with Monte Carlo simulations to prepare for the upcoming systematics-dominated landscape of neutrino measurements. In this work, we present the implementation of the Ghent Hybrid model for neutrino-induced single-pion production in the NuWro Monte Carlo event generator. The interaction dynamics includes coherently-added contributions from nucleon resonances and a non-resonant background, merged into the pythia branching predictions in the deep-inelastic regime, as instrumented by NuWro. This neutrino-nucleon interaction model is fully incorporated into the nuclear framework of the generator, allowing it to account for the influence of both initial- and final-state nuclear medium effects. We compare the predictions of this integrated implementation with recent pion production data from accelerator-based neutrino experiments. The results of the novel model show improved agreement of the generator predictions with the data and point to the significance of the refined treatment of the description of pion-production processes beyond the $Δ$ region.
↳ hep-phhep-exnucl-thJHEP(2024)·22 citations

Affiliations

first authorsco-authorsvia INSPIRE

Baryon-number -flavor separation in the topological expansion of QCD

Onset of scaling violation in pion and kaon elastic electromagnetic form factors

Amplitude analysis of B0→KS0​K+K− decays in a quasi-two-body QCD factorization approach

Longitudinal spin polarization in a thermal model with dissipative corrections

The Ghent Hybrid Model in NuWro: a new neutrino single-pion production model in the GeV regime

Affiliations

Amplitude analysis of $B^{0} \to K_{S}^{0} K^{+} K^{-}$ decays in a quasi-two-body QCD factorization approach