Nuclear Theory·nucl-th

Tuesday·July 9, 2024

15 papers—7 primary·8 cross-listed

08
[Submitted on 5 Jul 2024] (cross-list from hep-ph)
Gluon to $q q ˉ$ antenna in anisotropic QCD matter: spin-polarized and azimuthal jet observables
João Barata🇺🇸 · Carlos A. Salgado🇪🇸 · João M. Silva🇪🇸
We study the production of a quark-antiquark antenna in the presence of a dense and anisotropic QCD medium. We assume the antenna to originate from an unpolarized gluon state, and consider both massless and massive final states. The medium anisotropy is captured by allowing the jet quenching coefficient to take different magnitudes in orthogonal directions with respect to the jet axis. We find that the final particle distribution is sensitive to the medium anisotropy, and more importantly, that this effect couples directly to the helicity/spin of the final states. We propose to look into these effects by performing a Fourier decomposition of the particle distribution inside the jet. In our medium model, we find that the spin independent terms contribute to the even harmonics of the cosine series. The helicity/spin dependence enters only through the sine Fourier series. We further explore the spin dependence by examining the degree of polarization of the final states in different directions. Our results indicate that the anisotropies present in the QCD matter produced in heavy ion collisions can be probed by studying azimuthal and spin observables inside jets.
Comments:
33 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2407.04774 [pdf]
JHEP(2024)·30 citations
09
[Submitted on 6 Jul 2024] (cross-list from hep-ph)
QCD Masterclass Lectures on Jet Physics and Machine Learning
Andrew J. Larkoski🇺🇸
These lectures were presented at the 2024 QCD Masterclass in Saint-Jacut-de-la-Mer, France. They introduce and review fundamental theorems and principles of machine learning within the context of collider particle physics, focused on application to jet identification and discrimination. Numerous examples of binary discrimination in jet physics are studied in detail, including $H \to b b ˉ$ identification in fixed-order perturbation theory, generic one-versus two-prong discrimination with parametric power counting techniques, and up versus down quark jet classification by assuming the central limit theorem, isospin conservation, and a convergent moment expansion of the single particle energy distribution. Quark versus gluon jet discrimination is considered in multiple contexts, from using additive, infrared and collinear safe observables, to using hadronic multiplicity, and to including measurements of the jet charge. While many of the results presented here are well known, some novel results are presented, the most prominent being a parametrized expression for the likelihood ratio of quark versus gluon discrimination for jets on which hadronic multiplicity and jet charge are simultaneously measured. End-of-lecture exercises are also provided.
Comments:
130 pages, 32 figures, 603 references; v2: fixed some minor typos, accepted to EPJC
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2407.04897 [pdf]
EPJC(2024)·20 citations
10
[Submitted on 7 Jul 2024] (cross-list from hep-ph)
Impact of finite volume on kaon, antikaon, and $ϕ$ meson masses and decay width in asymmetric strange hadronic matter
Zeeshan Ahmad🇮🇳 · Nisha Chahal🇮🇳 · Arvind Kumar🇮🇳 · Suneel Dutt🇮🇳
In the present work, we investigate the impact of finite volume on the in-medium properties of kaons ( $K^{+}$ , $K^{0}$ ) and antikaons ( $K^{-}$ , $K^{0} ˉ$ ), and $ϕ$ mesons in the isospin asymmetric strange hadronic medium at finite density and temperature. We use the chiral SU(3) hadronic mean-field model, which accounts for the interactions between baryons through the exchange of scalar ( $σ, ζ, δ$ ) and vector ( $ω$ , $ρ$ , $ϕ$ ) fields. To investigate the effects of finite volume, we apply the multiple reflection expansion (MRE) technique for calculations of the density of states. The non-strange scalar field $σ$ shows significant variation in an asymmetric medium, while the strange scalar field $ζ$ shows good dependency in the strange medium. We use the medium-modified masses of kaons and antikaons calculated using the chiral SU(3) model to obtain the masses and decay width of $ϕ$ mesons in finite volume hadronic medium. To obtain the masses and decay widths of $ϕ$ mesons, an effective Lagrangian approach with $ϕ$ $K$ $K ˉ$ interactions at one-loop level is used in the present work. We obtain the effective masses and decay widths in the finite volume matter, for the spherical geometry of the medium with Neumann and Dirichlet boundary conditions as well as for the cubic geometry. The finite volume effects are found to be appreciable at high baryon densities.
Comments:
40 pages and 13 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2407.05263 [pdf]
PTEP(2025)·4 citations
11
[Submitted on 7 Jul 2024] (cross-list from hep-ph)
Pion photoproduction of nucleon excited states with Hamiltonian effective field theory
Yu Zhuge🇨🇳 · Zhan-Wei Liu🇨🇳 · Derek B. Leinweber🇦🇺 · Anthony W. Thomas🇦🇺
We refine our previous calculation of multipole amplitude $E_{0 +}$ for pion photoproduction process, $γ N \to π N$ . The treatment of final-state interactions is based upon an earlier analysis of pion-nucleon scattering within Hamiltonian effective field theory, supplemented by incorporating contributions from the $N^{*} (1650)$ and the $K Λ$ coupled channel. The contribution from the bare state corresponding to the $N^{*} (1650)$ significantly enhances our results. Additionally, we also compute the multipole amplitude $M_{1 -}$ , which is of direct relevance to the Roper resonance. The results are comparable with other dynamical coupled channel models, even though the contribution from the bare state (interpreted as a 2 $s$ excitation) in this channel is small because of its large mass.
Comments:
14 pages, 9 figures, 3 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2407.05334 [pdf]
PRD(2024)·14 citations
12
[Submitted on 8 Jul 2024] (cross-list from hep-ph)
Probing the nature of the anticharmed-strange pentaquark states: mass spectra, decays, and magnetic moments
Xuejie Liu🇨🇳 · Yue Tan🇨🇳 · Xiaoyun Chen🇨🇳 · Dianyong Chen🇨🇳 · Hongxia Huang🇨🇳 · Jialun Ping🇨🇳
Within the framework of the quark delocalization color screening model, a systematic investigation of the anticharmed-strange pentaquark system is performed using the resonance group method. The currently estimations predict three bound states with estimated masses to be 2886 MeV, 3039 MeV, and 3153 MeV, respectively. Additionally, three resonance states are identified in various scattering phase shifts processes. Among them, two resonance states $Σ D$ and $Σ^{*} D^{*}$ with quantum number $\frac{1}{2} (\frac{1}{2}^{-})$ are detected in channels $N D_{s}^{*}$ and $N D$ , and $Σ D^{*}$ and $Λ D$ , with masses and decay widths of ( $M_{R} = 3053 \sim 3055$ MeV, $T_{t o t a l} = 13.0 \sim 13.4$ MeV) and ( $M_{R} = 3389 \sim 3390$ MeV, $T_{t o t a l} = 10.4$ MeV), respectively. In the $Λ D^{*}$ and $Σ D^{*}$ channels, a resonance state with quantum number $\frac{1}{2} (\frac{3}{2}^{-})$ is discovered, with its mass and decay width being $3250 \sim 3252$ MeV and 4.4 MeV, respectively. These predicted pentaquark states have $c ˉ s nnn$ quark compositions, allowing them to be recognized as genuine pentaquark states. To validate these predictions, it is expected that upcoming experiments will further explore the predicted resonance and bound states in these possible decay channels.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2407.05598 [pdf]
PRD(2024)·3 citations
13
[Submitted on 8 Jul 2024] (cross-list from nucl-ex)
Effect of ground-state deformation on the Isoscalar Giant Monopole Resonance and the first observation of overtones of the Isoscalar Giant Quadrupole Resonance in rare-earth Nd isotopes
M. Abdullah · S. Bagchi · M.N. Harakeh · H. Akimune · D. Das · T. Doi · L. M. Donaldson · Y. Fujikawa · M. Fujiwara · T. Furuno · U. Garg · Y.K. Gupta and 24 other authors
The strength distributions of the Isoscalar Giant Monopole Resonance (ISGMR) and Isoscalar Giant Quadrupole Resonance (ISGQR) in 142,146-150Nd have been determined via inelastic alpha-particle scattering with the Grand Raiden (GR) Spectrometer at the Research Center for Nuclear Physics (RCNP), Japan. In the deformed nuclei 146-150Nd, the ISGMR strength distributions exhibit a splitting into two components, while the nearly spherical nucleus 142Nd displays a single peak in the ISGMR strength distribution. A noteworthy achievement in this study is the first-time detection of overtones in the Isoscalar Giant Quadrupole Resonance (ISGQR) strength distributions within Nd isotopes at an excitation energy around 25 MeV obtained through Multipole Decomposition Analysis (MDA).
Comments:
Accepted for publication in Physics Letters B
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2407.05685 [pdf]
PLB(2024)·6 citations
14
[Submitted on 8 Jul 2024] (cross-list from hep-ph)
Studying the $Ξ (2030)$ as a predominantly $K ˉ^{*} Σ$ molecular state
Jing-wen Feng · Cai Cheng · Yin Huang
Since its discovery in 1977, the spin-parity of $Ξ (2030)$ has not been fully determined experimentally. The latest Particle Data Group (PDG) listing suggests it may be a baryon with $J = 5/2$ . Therefore, studying the mass spectrum and decay properties of $Ξ (2030)$ has become a current hot topic to definitively establish its spin-parity. As the three-quark model fails to explain $Ξ (2030)$ , we previously proposed it may be a molecule primarily composed of $K ˉ Σ$ with $J^{P} = 5/ 2^{+}$ , based on its mass spectrum study. To verify its molecular state interpretation, this work proposes studying the strong decays of $Ξ (2030)$ assuming it is a $P$ -wave $J^{P} = 5/ 2^{+}$ meson-baryon molecule predominantly composed of $K ˉ Σ$ . We calculated all experimentally measured two-body and three-body final state decay widths of $Ξ (2030)$ , including $Ξ (2030) \to K ˉ Λ, K ˉ Σ, π Ξ, π Ξ^{*}$ , and $Ξ (2030) \to π π Ξ, π K ˉ Σ, π K ˉ Λ$ . The results indicate that both the total decay width and partial decay widths agree well with experimental values within the error margins. This supports that $Ξ (2030)$ is a molecule with spin-parity $J^{P} = 5/ 2^{+}$ , predominantly composed of $K ˉ^{*} Σ$ . Compared to the experimental central values, our results are slightly smaller, which suggests that $Ξ (2030)$ may contain additional components besides meson-baryon molecular components, such as three quark structures.
Comments:
8 papers,6 figures,1 table
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2407.05697 [pdf]
0 citations
15
[Submitted on 8 Jul 2024] (cross-list from hep-ph)
Light nuclei photoproduction in relativistic heavy ion ultraperipheral collisions
Jin-Yu Hu🇨🇳 · Shuo Lin🇨🇳 · Shi Pu🇨🇳 · Qun Wang🇨🇳
We have investigated light nuclei pair photoproduction in relativistic heavy ion ultraperipheral collisions. As a first attempt, we employ our previously developed quantum electrodynamics model, which incorporates a wave-packet description of initial nuclei, to compute the cross section for proton-antiproton pair photoproduction. The effective vertex for the photon and proton interaction is chosen based on studies of two-photon exchange effects in hadron physics. We present the transverse momentum, invariant mass, and azimuthal angle distributions of proton-antiproton pairs at $s_{N N} = 200$ GeV in Au+Au ultraperipheral collisions. We observe a $cos (2 ϕ)$ modulation and an almost negligible $cos (4 ϕ)$ modulation in the azimuthal angle distribution. Our studies helps us better understand the matter generated by light.
Comments:
6 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2407.06091 [pdf]
4 citations

Affiliations

first authorsco-authorsvia INSPIRE