Nuclear Theory·nucl-th

Wednesday·April 6, 2022

18 papers—9 primary·9 cross-listed

10
Magnetic impurity in a one-dimensional few-fermion system
Lukas Rammelmüller · David Huber · Matija Čufar · Joachim Brand · Hans-Werner Hammer · Artem G. Volosniev
We present a numerical analysis of spin- $\frac{1}{2}$ fermions in a one-dimensional harmonic potential in the presence of a magnetic point-like impurity at the center of the trap. The model represents a few-body analogue of a magnetic impurity in the vicinity of an $s$ -wave superconductor. Already for a few particles we find a ground-state level crossing between sectors with different fermion parities. We interpret this crossing as a few-body precursor of a quantum phase transition, which occurs when the impurity `breaks' a Cooper pair. This picture is further corroborated by analyzing density-density correlations in momentum space. Finally, we discuss how the system may be realized with existing cold-atoms platforms.
↳ cond-mat.quant-gascond-mat.supr-connucl-thSciPost Phys.(2023)·9 citations
11
Quasi-stationary sequences of hyper massive neutron stars with exotic equations of state
Sanika Khadkikar · Chatrik Singh Mangat · Sarmistha Banik
In this work, we study the effect of differential rotation, finite temperature and strangeness on the quasi stationary sequences of hyper massive neutron stars (HMNS). We generate constant rest mass sequences of differentially rotating and uniformly rotating stars. The nucleonic matter relevant to the star interior is described within the framework of the relativistic mean field model with the DD2 parameter set. We also consider the strange $Λ$ hyperons using the BHB $Λ ϕ$ equation of state (EoS). Additionally, we probe the behaviour of neutron stars (NS) with these compositions at different temperatures. We report that the addition of hyperons to the EoS produces a significant boost to the spin-up phenomenon. Moreover, increasing the temperature can make the spin-up more robust. We also study the impact of strangeness and thermal effects on the T/W instability. Finally, we analyse equilibrium sequences of a NS following a stable transition from differential rotation to uniform rotation. The decrease in frequency relative to angular momentum loss during this transition is significantly smaller for EoS containing hyperons, compared to nucleonic EoS.
↳ astro-ph.HEnucl-thJ.Astrophys.Astron.(2022)·1 citation
12
Molecular states from $B ˉ^{(*)} N$ interactions
Zhong-Yi Jian🇨🇳 · Hong Qiang Zhu🇨🇳 · Feng Yang🇨🇳 · Qi-Hui Chen🇨🇳 · Yin Huang🇨🇳 · Jun He🇨🇳
In 2019, two new structures $Λ_{b} (6146)$ and $Λ_{b} (6152)$ were observed by the LHCb Collaboration at the invariant mass spectrum of $Λ_{b}^{0} π^{+} π^{-}$ , which aroused a hot discussion about their inner structures. The $Λ_{b} (6146)$ and $Λ_{b} (6152)$ might still be molecular states because their masses are close to threshold of a $B ˉ$ meson and a nucleon. In this work, we perform a systematical investigation of possible heavy baryonic molecular states from the $B ˉ N$ interaction. Since the $B ˉ N$ channel strongly couples to the $B ˉ^{*} N$ channel, the possible $B ˉ N - B ˉ^{*} N$ bound states are also studied. The interaction of the system considered is described by the $t$ -channel $σ$ , $π$ , $η$ , $ω$ , and $ρ$ mesons exchanges. By solving the non-relativistic Schrödinger equation with the obtained one-boson-exchange potentials, the $B ˉ^{(*)} N$ bound states with different quantum numbers are searched. The calculation suggests that recently observed $Λ_{b} (6146)$ can be assigned as a $P$ -wave $B ˉ N$ molecular state with spin parity $J^{P} = 3/ 2^{+}$ or a $B ˉ N - B ˉ^{*} N$ bound state. However, assignment of $Λ_{b} (6152)$ as an $F$ -wave $B ˉ N$ molecular is disfavored. The $Λ_{b} (6152)$ can be explained as meson-baryon molecular state with a small $B ˉ N$ component. The calculation also predict the existence of two $S$ -wave $B ˉ N - B ˉ^{*} N$ bound states that can be related to the experimentally observed $Λ_{b} (5912)$ and $Λ_{b} (5920)$ .
↳ hep-phnucl-thEPJA(2023)·6 citations
13
Parton energy loss at LHC tests for a strongly coupled medium
Sourendu Gupta🇮🇳 · Rishi Sharma🇮🇳
We construct a measure of transverse momentum loss of jets in nuclear collisions at LHC directly using measurements of jet cross sections in PbPb and pp collisions. The proposal is shown to be equivalent to R_AA and is equally straightforward to construct. Using data from the ATLAS collaboration at two different collision energies, we show that the proposed measure has small statistical uncertainties. We argue that systematic errors can be easily improved over our estimates by the experimental collaboration to such an extent that it directly probes whether the jet-medium interaction is due to a strongly interacting medium or a weakly interacting plasma. We argue that the current data may marginally favour a strongly interacting medium. On the other hand, assuming that the medium is weakly interacting, we are able to provide estimates of the jet quenching parameter qhat which are in rough agreement with previously reported estimates.
↳ hep-phhep-exnucl-exnucl-th0 citations
14
Local and global polarization of $Λ$ hyperons across RHIC-BES energies: the roles of spin hall effect, initial condition and baryon diffusion
Xiang-Yu Wu🇨🇳 · Cong Yi🇨🇳 · Guang-You Qin🇨🇳 · Shi Pu🇨🇳
We perform a systematic study on the local and global spin polarization of $Λ$ and $Λ$ hyperons in relativistic heavy-ion collisions at beam energy scan energies via the (3+1)-dimensional CLVisc hydrodynamics model with AMPT and SMASH initial conditions. Following the quantum kinetic theory, we decompose the polarization vector as the parts induced by thermal vorticity, shear tensor and the spin Hall effect (SHE). We find that the polarization induced by SHE and the total polarization strongly depends on the initial conditions. At $7.7$ GeV, SHE gives a sizeable contribution and even flips the sign of the local polarization along the beam direction for AMPT initial condition, which is not observed for SMASH initial condition. Meanwhile, the local polarization along the out-of-plane direction induced by SHE with AMPT initial condition does not always increase with decreasing collision energies. Next, we find that the polarization along the beam direction is sensitive to the baryon diffusion coefficient, but the local polarization along the out-of-plane direction is not. Our results for the global polarization of $Λ$ and $Λ$ agree well with the STAR data. Interestingly, the global polarization of $Λ$ is not always larger than that of $Λ$ due to various competing effects. Our findings are helpful for understanding the polarization phenomenon and the detailed structure of quark-gluon plasma in relativistic heavy-ion collisions.
↳ hep-phnucl-exnucl-thPRC(2022)·78 citations
15
Molecular formations and spectra due to electron correlations in three-electron hybrid double-well qubits
Constantine Yannouleas🇺🇸 · Uzi Landman🇺🇸
We show that systematic full configuration-interaction (FCI) calculations enable prediction of the energy spectra and the intrinsic spatial and spin structures of the many-body wave functions as a function of the detuning parameter for the case of three-electron hybrid qubits based on GaAs asymmetric double quantum dots. Specifically, in comparison with the case of weak interactions and treating the entire three-electron double-dot hybrid qubit as an integral unit, it is shown that the predicted spectroscopic patterns, originating from strong electron correlations, manifest the formation of Wigner molecules (WMs). Signatures of WM formation include: (1) a strong suppression of the energy gaps relative to the non-interacting-electrons modeling, and (2) the appearance of a pair of avoided crossings arising between states associated with two-electron occupancies in the left and right wells. The Wigner molecule is a physical entity associated with electron localization within each well and it cannot be captured by the previously employed independent-particle or two-site-Hubbard theoretical modeling of the hybrid qubits. The emergence of strong WMs is investigated in depth through the concerted use of FCI-adapted diagnostic tools like charge and spin densities, as well as conditional probability distributions. Furthermore, the energy spectrum as a function of the strength of the Coulomb repulsion (at constant detuning) is calculated in order to complement the thorough analysis of the factors contributing to WM emergence. We report remarkable agreement with recent experimental measurements. The present FCI methodology for multi-well quantum dots can be straightforwardly extended to treat valleytronic two-band Si/SiGe hybrid qubits, where the central role of the WMs was confirmed recently.
↳ cond-mat.mes-hallnucl-thquant-phPRB(2022)·14 citations
16
Three-body molecules $D ˉ D ˉ^{*} Σ_{c}$ - understanding the nature of $T_{cc}$ , $P_{c} (4312)$ , $P_{c} (4440)$ and $P_{c} (4457)$
Ya-Wen Pan🇨🇳 · Tian-Wei Wu🇨🇳 · Ming-Zhu Liu🇨🇳 · Li-Sheng Geng🇨🇳
The nature of the three pentaquark states, $P_{c} (4312)$ , $P_{c} (4440)$ and $P_{c} (4457)$ , discovered by the LHCb Collaboration in 2019, is still under debate, although the $D ˉ^{(*)} Σ_{c}$ molecular interpretation seems to be the most popular. In this work, by adding a $D ˉ$ meson into the $D ˉ^{*} Σ_{c}$ pair, we investigate the mass and decay width of the three-body molecules $D ˉ D ˉ^{*} Σ_{c}$ and explore the correlation between the existence of the $D ˉ D ˉ^{*} Σ_{c}$ molecules with the existence of $D ˉ^{(*)} Σ_{c}$ and $D ˉ^{*} D ˉ$ two-body molecules. The latter can be identified with the doubly charmed tetraquark state $T_{cc}$ recently discovered by the LHCb Collaboration. Based on the molecular nature of $P_{c} (4312)$ , $P_{c} (4440)$ , $P_{c} (4457)$ , and $T_{cc}$ , our results indicate that there exist two three-body bound states of $D ˉ D ˉ^{*} Σ_{c}$ with $I (J^{P}) = 1 (1/ 2^{+})$ and $I (J^{P}) = 1 (3/ 2^{+})$ , and binding energies $37.24$ MeV and $29.63$ MeV below the $D ˉ D ˉ^{*} Σ_{c}$ mass threshold. In addition, we find that the mass splitting of these two three-body molecules are correlated to the mass splitting of $P_{c} (4440)$ and $P_{c} (4457)$ , which offers a non-trivial way to reveal the molecular nature of these states. The partial widths of two $D ˉ D ˉ^{*} Σ_{c}$ molecules decaying into $J / ψ p D ˉ$ and $J / ψ p D ˉ^{*}$ are found to be several MeV. We recommend the experimental searches for the $D ˉ D ˉ^{*} Σ_{c}$ molecules in the $J / ψ p D ˉ$ and $J / ψ p D ˉ^{*}$ invariant mass distributions.
↳ hep-phnucl-thPRD(2022)·16 citations
17
Anisotropic tomography of heavy quark dissociation by using general propagator structure at finite magnetic field
Ritesh Ghosh🇮🇳 · Aritra Bandyopadhyay🇨🇳 · Indrani Nilima🇮🇳 · Sabyasachi Ghosh🇮🇳
In this work we have explored the imaginary part of the Heavy Quark (HQ) potential and subsequently the dissociation of heavy quarkonia at finite temperature and magnetic field. With respect to earlier investigations on this topic, present work contain three new ingredients. First one is considering all Landau level summation, for which present work can be applicable in entire magnetic field domain - from weak to strong. Second one is the general structure of the gauge boson propagator in a hot magnetized medium, which is used here in heavy quark potential problem first time. Third one is a rich anisotropic structure of the complex heavy quark potential, which explicitly depends on the longitudinal and transverse distance. By comparing with earlier references, we have attempted to display our new contributions by plotting heavy quark potential tomography and dissociation probability at finite temperature and magnetic field.
↳ hep-phnucl-thPRD(2022)·21 citations
18
Heavy quark potential and LQCD based quark condensate at finite magnetic field
Indrani Nilima🇮🇳 · Aritra Bandyopadhyay🇨🇳 · Ritesh Ghosh🇮🇳 · Sabyasachi Ghosh🇮🇳
In the present work, we have studied heavy quarkonia potential in hot and magnetized quark gluon plasma. Inverse magnetic catalysis (IMC) effect is incorporated within the system through the magnetic field modified Debye mass by modifying the effective quark masses. We have obtained the real and imaginary part of the heavy quark potential in this new scenario. After the evaluation of the binding energy and the decay width we comment about the dissociation temperatures of the heavy quarkonia in presence of magnetic field.
↳ hep-phnucl-thEPJC(2023)·17 citations

Affiliations

first authorsco-authorsvia INSPIRE