Nuclear Theory·nucl-th

Tuesday·March 5, 2024

18 papers—11 primary·7 cross-listed

12
Strangeness plus-one ( $S = + 1$ ) resonance-state $P_{0}^{+*}$ via $K^{+} n \to K^{* 0} p$
Dayoung Lee🇰🇷 · Seung-il Nam🇰🇷
In our current study, we delve into the peak-like structure observed during the reaction process of $K^{+} n \to K^{0} p$ at approximately $s \sim 2.5$ GeV. Our focus centers on exploring the potential $S = + 1$ resonance $P_{0}^{+*} \equiv P_{0}^{*}$ as an excited state within the extended vector-meson and baryon ( $V B$ ) antidecuplet. To achieve this aim, we employ the effective Lagrangian method in conjunction with the $(u, t)$ -channel Regge approach, operating within the tree-level Born approximation. We thoroughly examine various spin-parity quantum numbers for the resonance, resulting in a compelling description of the data, where $M_{P_{0}^{*}} \approx 2.5$ GeV and $Γ_{P_{0}^{*}} \approx 100$ MeV. Furthermore, we propose an experimental technique to amplify the signal-to-noise ratio ( $S / N$ ) for accurately measuring the resonance. Notably, our findings reveal that background interference diminishes significantly within the $K^{*}$ forward-scattering region in the center-of-mass frame when the $K^{*}$ is perpendicularly polarized to the reaction plane. Additionally, we explore the recoil-proton spin asymmetry to definitively determine the spin and parity of the resonance. This study stands to serve as a valuable reference for designing experimental setups aimed at investigating and comprehending exotic phenomena in QCD. Specifically, our insights will inform future J-PARC experiments, particularly those employing higher kaon beam energies.
↳ hep-phnucl-exnucl-thPRC(2024)·2 citations
13
Study of identified particle production as a function of transverse event activity classifier, $S_{T}$ in p $-$ p collisions
Rahul Verma🇮🇳 · Vishu Saini🇮🇳 · Basanta Nandi🇮🇳 · Sadhana Dash🇮🇳
A new observable, $S_{T}$ , is introduced in terms of the sum of the transverse momentum of charged particles ( $\sum_{i} p_{T_{i}}$ ) produced in proton proton (p $-$ p) collisions at LHC energies to probe the underlying events (UE). The UE are defined as those aspects of proton-proton collisions that are not attributed to the primary hard scattering process, but rather to the accompanying interactions of the rest of the proton. The conventional approach of studying underlying events is usually carried out by defining topological regions with respect to the leading particle in an event. The transverse region is generally sensitive to UE and various classifiers have been used to discriminate the extent of UE activity regions. The production of identified particles like $π^{\pm}$ , $K^{\pm}$ , p , $K_{S}^{0}$ , and $Λ^{0}$ are studied in different ranges of transverse activity classifier in p $-$ p collisions at $s = 13$ TeV using pQCD inspired PYTHIA 8 event generator. A comparative analysis of the identified particle spectra, mean multiplicity and mean transverse momentum has been carried out with respect to $S_{T}$ and the performance of this new observable is gauged by comparing the results with previously defined $R_{T}$ observable.
↳ hep-phnucl-thEur.Phys.J.Plus(2025)·2 citations
14
Analyzing the transport coefficients and observables of a rotating QGP medium in kinetic theory framework with a novel approach to the collision integral
Shubhalaxmi Rath🇨🇱 · Sadhana Dash🇮🇳
In the present work, we have studied how the rotation of the QGP medium affects the transport coefficients and observables in heavy ion collisions. For the noncentral collisions, although most of the angular momentum gets carried away by the spectators, there still remains a finite angular momentum with a finite range of angular velocity, which thus incites rotation in the produced matter. As a result, various properties of the QGP medium including its transport properties are most likely to be modulated by the rotation. We have calculated the transport coefficients and observables, such as the electrical conductivity, the thermal conductivity, the Knudsen number, the elliptic flow, the specific heat at constant pressure, the specific heat at constant volume, the trace anomaly, the thermal diffusion constant and the isothermal compressibility using the kinetic theory to see the effect of rotation on them. In particular, we have used the novel relaxation time approximation for the collision integral in the relativistic Boltzmann transport equation to derive the transport coefficients and compared them with their values in the relaxation time approximation within the kinetic theory approach in conjunction with the finite angular velocity. We have found that the emergence of angular velocity enhances the flow of charge and heat in the medium. Further, as compared to the relaxation time approximation, the electrical and the thermal conductivities have smaller values in the novel relaxation time approximation and these differences between the conductivities in the said approximations are more pronounced at high temperatures than at low temperatures. Furthermore, all the aforesaid observables are found to be sensitive to the rotation of the QGP medium.
↳ hep-phhep-thnucl-thEPJC(2025)·7 citations
15
Identification of the $G (3900)$ as the P-wave $D D ˉ^{*} / D ˉ D^{*}$ resonance
Zi-Yang Lin🇨🇳 · Jun-Zhang Wang🇨🇳 · Jian-Bo Cheng🇨🇳 · Lu Meng🇩🇪 · Shi-Lin Zhu🇨🇳
The BESIII Collaboration recently performed a precise measurement of the $e^{+} e^{-} \to D D ˉ$ Born cross sections, and confirmed the $G (3900)$ structure reported by BaBar and Belle with high significance. We identify the $G (3900)$ as the first P-wave $\DDbar$ molecular resonance. The experimental and theoretical identification of the P-wave dimeson state holds paramount importance in enhancing our comprehension of the non-perturbative QCD and few-body physics. Its existence is firmly established in a unified meson-exchange model which simultaneously depicts the features of the $χ_{c 1} (3872)$ , $Z_{c} (3900)$ and $T_{cc} (3875)$ . This scenario can be directly examined in the $e^{+} e^{-} \to D D ˉ^{*} / D ˉ D^{*}$ cross section by seeing whether a resonance exists at the threshold. The credibility of the investigations is also ensured by the fact that the P-wave interaction dominantly arises from the well-known long-range pion exchange. Additionally, thanks to the centrifugal barrier, it is easier to form resonances in P-wave than in S-wave. We extensively calculate all systems up to P-wave with various quantum numbers and predict a dense population of the $\DDbar$ and $\DD$ states, where the S-wave $\DDbar$ state with $I^{G} (J^{P C}) = 0^{-} (1^{+-})$ , P-wave $\DDbar$ state with $I^{G} (J^{P C}) = 0^{+} (0^{-+})$ , and P-wave $\DD$ state with $I (J^{P}) = 0 (0^{-})$ are more likely to be observed in experiments.
↳ hep-phhep-exhep-latnucl-thPRL(2024)·35 citations
16
A Global View of the EDM Landscape
Skyler Degenkolb🇩🇪 · Nina Elmer🇩🇪 · Tanmoy Modak🇩🇪 · Margarete Mühlleitner🇩🇪 · Tilman Plehn🇩🇪
Permanent electric dipole moments (EDMs) are sensitive probes of the symmetry structure of elementary particles, which in turn is closely tied to the baryon asymmetry in the universe. A meaningful interpretation framework for EDM measurements has to be based on effective quantum field theory. We interpret the measurements performed to date in terms of a hadronic-scale Lagrangian, using the SFitter global analysis framework. We find that part of this Lagrangian is constrained very well, while some of the parameters suffer from too few high-precision measurements. Theory uncertainties lead to weaker model constraints, but can be controlled within the global analysis.
↳ hep-phnucl-thSciPost Phys.(2026)·18 citations
17
Neutron star cooling and mass distributions
H. C. Das🇮🇹 · Jin-Biao Wei🇨🇳 · G. F. Burgio🇮🇹 · H.-J. Schulze🇮🇹
We study the cooling of isolated neutron stars, employing different nuclear equations of state with or without active direct Urca process, and investigate the interplay with the nuclear pairing gaps. We find that a consistent description of all current cooling data requires fast direct Urca cooling and reasonable proton 1S0 gaps, but no neutron 3P2 pairing. We then deduce the neutron star mass distributions compatible with the cooling analysis and compare with current theoretical models. Reduced 1S0 gaps and unimodal mass distributions are preferred by the analysis. The importance of statistical and systematic errors is also investigated.
↳ astro-ph.HEnucl-thPRD(2024)·9 citations
18
On the study of new proxies for second order cumulants of conserved charges in heavy-ion collisions with EPOS4
Johannes Jahan🇺🇸 · Claudia Ratti🇺🇸 · Maria Stefaniak🇺🇸 · Klaus Werner🇫🇷
Proxies for cumulants of baryon number $B$ , electric charge $Q$ and strangeness $S$ are usually measured in heavy-ion collisions via moments of net-number distribution of given hadronic species. Since these cumulants of conserved charges are expected to be sensitive to the existence of a critical point in the phase diagram of nuclear matter, it is crucial to ensure that the proxies used as substitutes are as close to them as possible. Hence, we use the EPOS4 framework to generate Au+Au collisions at several collision energies of the RHIC Beam Energy Scan. We compute $2^{nd}$ order net-cumulants of $π$ , $K$ and $p$ , for which experimental data has been published, as well as the corresponding conserved charge cumulants. We then compare them with proxies, defined in previous lattice QCD and Hadron Resonance Gas model studies, which are shown to reproduce more accurately their associated conserved charge cumulants. We investigate the impact of hadronic re-scatterings occurring in the late evolution of the system on these quantities, as well as the amount of signal actually originating from the bulk medium which endures a phase transition.
↳ hep-phnucl-thPRC(2024)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE

Tuesday·March 5, 2024

Strangeness plus-one ( $S = + 1$ ) resonance-state $P_{0}^{+}$ via $K^{+} n \to K^{ 0} p$

Study of identified particle production as a function of transverse event activity classifier, $S_{T}$ in p $-$ p collisions

Analyzing the transport coefficients and observables of a rotating QGP medium in kinetic theory framework with a novel approach to the collision integral

Identification of the $G (3900)$ as the P-wave $D D ˉ^{} / D ˉ D^{}$ resonance

A Global View of the EDM Landscape

Neutron star cooling and mass distributions

On the study of new proxies for second order cumulants of conserved charges in heavy-ion collisions with EPOS4

Affiliations

Strangeness plus-one (S=+1) resonance-state P0+∗​ via K+n→K∗0p

Study of identified particle production as a function of transverse event activity classifier, ST​ in p−p collisions

Analyzing the transport coefficients and observables of a rotating QGP medium in kinetic theory framework with a novel approach to the collision integral

Identification of the G(3900) as the P-wave DDˉ∗/DˉD∗ resonance

A Global View of the EDM Landscape

Neutron star cooling and mass distributions

On the study of new proxies for second order cumulants of conserved charges in heavy-ion collisions with EPOS4

Affiliations

Strangeness plus-one ( $S = + 1$ ) resonance-state $P_{0}^{+}$ via $K^{+} n \to K^{ 0} p$

Study of identified particle production as a function of transverse event activity classifier, $S_{T}$ in p $-$ p collisions

Identification of the $G (3900)$ as the P-wave $D D ˉ^{} / D ˉ D^{}$ resonance