Nuclear Theory·nucl-th

Friday·February 26, 2021

12 papers—2 primary·10 cross-listed

01
Microscopic calculations of 6He and 6Li with real-time evolution method
Q. Zhao · B. Zhou · M. Kimura · H. Motoki · Seung-heon Shin
The low-lying cluster states of 6He (a+n+n) and 6Li (a+n+p) are calculated by the real-time evolution method (REM) which generates basis wave functions for the generator coordinate method (GCM) from the equation of motion of Gaussian wave packets. The 0+ state of 6He as well as the 1+, 0+ and 3+ states of 6Li are calculated as a benchmark. We also calculate the root-mean-square (r.m.s.) radii of the point matter, the point proton, and the point neutron of these states, particularly for the study of the halo characters of these two nuclei. It is shown that REM can be one constructive way for generating effective basis wave functions in GCM calculations.
nucl-thEPJA(2022)·9 citations
02
Role of tensor terms of the Skyrme energy-density functional on neutron deformed magic numbers in the rare-earth region
Kai-Wen Kelvin-Lee🇲🇾 · Meng-Hock Koh🇲🇾 · Ludovic Bonneau🇫🇷
The role of the tensor part of the nuclear interaction is actively investigated in recent years due to experimental advancement yielding new data in nuclei far from the $β$ -stability line. In this article we study the effect of this part of the nuclear interaction on deformed neutron magic numbers in the rare-earth region within the Skyrme energy-density functional for various TIJ \cite{lesinski:2007} parametrizations. Two quantities signaling magic numbers are considered: two-neutron separation energies and single-particle energies. They are calculated in isotopic series involving well-deformed rare-earth nuclei ranging from $Z = 64$ to $Z = 72$ in the $N = 100$ region. Obtained results show that, whereas the neutron-proton tensor contribution to binding energies is important to reproduce neutron sub-shell closure at $N = 104$ in heavier rare earths Yb ( $Z = 70$ ) and Hf ( $Z = 72$ ) isotopes, like-particle tensor also plays a role in the single-particle spectrum around Fermi level and is even favored in lighter Gd ( $Z = 64$ ) and Dy ( $Z = 66$ ) rare-earth isotopes.
nucl-thPRC(2021)·2 citations
03
Axions: From Magnetars and Neutron Star Mergers to Beam Dumps and BECs
Jean-François Fortin🇨🇦 · Huai-Ke Guo🇺🇸 · Steven P. Harris🇺🇸 · Doojin Kim🇺🇸 · Kuver Sinha🇺🇸 · Chen Sun🇮🇱
We review topics in searches for axion-like-particles (ALPs), covering material that is complementary to other recent reviews. The first half of our review covers ALPs in the extreme environments of neutron star cores, the magnetospheres of highly magnetized neutron stars (magnetars), and in neutron star mergers. The focus is on possible signals of ALPs in the photon spectrum of neutron stars and gravitational wave/electromagnetic signals from neutron star mergers. We then review recent developments in laboratory-produced ALP searches, focusing mainly on accelerator-based facilities including beam-dump type experiments and collider experiments. We provide a general-purpose discussion of the ALP search pipeline from production to detection, in steps, and our discussion is straightforwardly applicable to most beam-dump type and reactor experiments. We end with a selective look at the rapidly developing field of ultralight dark matter, specifically the formation of Bose-Einstein Condensates (BECs). We review the properties of BECs of ultralight dark matter and bridge these properties with developments in numerical simulations, and ultimately with their impact on experimental searches.
↳ hep-phastro-ph.HEnucl-thInt.J.Mod.Phys.D(2021)·38 citations
04
Simulation of Collective Neutrino Oscillations on a Quantum Computer
Benjamin Hall🇺🇸 · Alessandro Roggero🇺🇸 · Alessandro Baroni🇺🇸 · Joseph Carlson🇺🇸
In astrophysical scenarios with large neutrino density, like supernovae and the early universe, the presence of neutrino-neutrino interactions can give rise to collective flavor oscillations in the out-of-equilibrium collective dynamics of a neutrino cloud. The role of quantum correlations in these phenomena is not yet well understood, in large part due to complications in solving for the real-time evolution of the strongly coupled many-body system. Future fault-tolerant quantum computers hold the promise to overcome much of these limitations and provide direct access to the correlated neutrino dynamic. In this work, we present the first simulation of a small system of interacting neutrinos using current generation quantum devices. We introduce a strategy to overcome limitations in the natural connectivity of the qubits and use it to track the evolution of entanglement in real-time. The results show the critical importance of error-mitigation techniques to extract meaningful results for entanglement measures using noisy, near term, quantum devices.
↳ quant-phhep-thnucl-thPRD(2021)·89 citations
05
Masses of positive- and negative-parity hadron ground-states, including those with heavy quarks
Pei-Lin Yin🇨🇳 · Zhu-Fang Cui🇨🇳 · Craig D. Roberts🇨🇳 · Jorge Segovia🇪🇸
A symmetry-preserving treatment of a vector $\times$ vector contact interaction is used to compute spectra of ground-state $J^{P} = 0^{\pm}, 1^{\pm}$ $(f g ˉ)$ mesons, their partner diquark correlations, and $J^{P} = 1/ 2^{\pm}, 3/ 2^{\pm}$ $(f g h)$ baryons, where $f, g, h \in {u, d, s, c, b}$ . Results for the leptonic decay constants of all mesons are also obtained, including scalar and pseudovector states involving heavy quarks. The spectrum of baryons produced by this chiefly algebraic approach reproduces the 64 masses known empirically or computed using lattice-regularised quantum chromodynamics with an accuracy of 1.4(1.2)%. It also has the richness of states typical of constituent-quark models and predicts many baryon states that have not yet been observed. The study indicates that dynamical, nonpointlike diquark correlations play an important role in all baryons; and, typically, the lightest allowed diquark is the most important component of a baryon's Faddeev amplitude.
↳ hep-phhep-exhep-latnucl-ex+1EPJC(2021)·66 citations
06
The imaginary part of the heavy-quark potential from real-time Yang-Mills dynamics
Kirill Boguslavski🇦🇹 · Babak S. Kasmaei🇺🇸 · Michael Strickland🇺🇸
We extract the imaginary part of the heavy-quark potential using classical-statistical simulations of real-time Yang-Mills dynamics in classical thermal equilibrium. The $r$ -dependence of the imaginary part of the potential is extracted by measuring the temporal decay of Wilson loops of spatial length $r$ . We compare our results to continuum expressions obtained using hard thermal loop theory and to semi-analytic lattice perturbation theory calculations using the hard classical loop formalism. We find that, when plotted as a function of $m_{D} r$ , where $m_{D}$ is the hard classical loop Debye mass, the imaginary part of the heavy-quark potential shows little sensitivity to the lattice spacing at small $m_{D} r ≲ 1$ and agrees well with the semi-analytic hard classical loop result. For large quark-antiquark separations, we quantify the magnitude of the non-perturbative long-range corrections to the imaginary part of the heavy-quark potential. We present our results for a wide range of temperatures, lattice spacings, and lattice volumes. This work sets the stage for extracting the imaginary part of the heavy-quark potential in an expanding non-equilibrium Yang Mills plasma.
↳ hep-phhep-latnucl-thJHEP(2021)·12 citations
07
Bragg-Curve Simulation of Carbon-Ion Beams for Particle-therapy Applications: a study with the GEANT4 toolkit
M. Kh. Hamad
We used the GEANT4 Monte Carlo MC Toolkit to simulate carbon ion beams incident on water, tissue, and bone, taking into account nuclear fragmentation reactions. Upon increasing the energy of the primary beam, the position of the Bragg-Peak transfers to a location deeper inside the phantom. For different materials, the peak is located at a shallower depth along the beam direction and becomes sharper with increasing electron density NZ. Subsequently, the generated depth dose of the Bragg curve is then benchmarked with experimental data from GSI in Germany. The results exhibit a reasonable correlation with GSI experimental data with an accuracy of between 0.02 and 0.08 cm, thus establishing the basis to adopt MC in heavy-ion treatment planning. The Kolmogorov-Smirnov K-S test further ascertained from a statistical point of view that the simulation data matched the experimentally measured data very well. The two-dimensional isodose contours at the entrance were compared to those around the peak position and in the tail region beyond the peak, showing that bone produces more dose, in comparison to both water and tissue, due to secondary doses. In the water, the results show that the maximum energy deposited per fragment is mainly attributed to secondary carbon ions, followed by secondary boron and beryllium. Furthermore, the number of protons produced is the highest, thus making the maximum contribution to the total dose deposition in the tail region. Finally, the associated spectra of neutrons and photons were analyzed. The mean neutron energy value was found to be 16.29 MeV, and 1.03 MeV for the secondary gamma. However, the neutron dose was found to be negligible as compared to the total dose due to their longer range.
↳ physics.med-phnucl-thNucl.Eng.Tech.(2021)·0 citations
08
Factorization and transverse phase-space parton distributions
Bin Wu🇨🇭
We first revisit impact-parameter dependent collisions of ultra-relativistic particles in quantum field theory. Two conditions sufficient for defining an impact-parameter dependent cross section are given, which could be violated in proton-proton collisions. By imposing these conditions, a general formula for the impact-parameter dependent cross section is derived. Then, using soft-collinear effective theory, we derive a factorization formula for the impact-parameter dependent cross section for inclusive hard processes with only colorless final-state products in hadron and nuclear collisions. It entails defining thickness beam functions, which are Fourier transforms of transverse phase-space parton distribution functions. By modelling non-perturbative modes in thickness beam functions of large nuclei in heavy-ion collisions, the factorization formula confirms the cross section in the Glauber model for hard processes. Besides, the factorization formula is verified up to one loop in perturbative QCD for the inclusive Drell-Yan process in quark-antiquark collisions at a finite impact parameter.
↳ hep-phhep-exnucl-exnucl-thJHEP(2021)·10 citations
09
Alice meets Boojums in neutron stars: vortices penetrating two-flavor quark-hadron continuity
Yuki Fujimoto🇯🇵 · Muneto Nitta🇯🇵
Alice and Boojums are both representative characters created by Lewis Carroll. We show that they possibly meet in cores of rotating neutron stars. Recent studies of quark-hadron continuity suggest that neutron superfluid matter can connect smoothly to two-flavor symmetric quark matter at high densities. We study how this can be maintained in the presence of the vortices. In the neutron matter, quantized superfluid vortices arise. In the two-flavor dense quark matter, vortices carrying color magnetic fluxes together with fractionally quantized superfluid circulations appear as the most stable configuration, and we call these as the non-Abelian Alice strings. We show that three integer neutron superfluid vortices and three non-Abelian Alice strings of different color magnetic fluxes with total color flux canceled out are joined at a junction called a Boojum.
↳ hep-phastro-ph.HEcond-mat.supr-conhep-th+1PRD(2021)·12 citations
10
$Z_{N}$ symmetry in $S U (N)$ gauge theories
Minati Biswal🇮🇳 · Sanatan Digal🇮🇳 · Vinod Mamale🇮🇳 · Sabiar Shaikh🇮🇳
We study $Z_{N}$ symmetry in $S U (N)$ gauge theories in the presence of matter fields in the fundamental representation, by restricting the lattice partition function integration to matter fields which are uniform in spatial directions and gauge fields with vanishing spatial components. In this approximation the gauge matter field interaction effectively reduces to a 1-dimensional gauged chain. This makes analytical calculations of the matter field contribution to the Polyakov loop free energy possible. We show that in the limit of large number of temporal sites the explicit breaking of $Z_{N}$ symmetry in this free energy vanishes, driven by dominance of the density of states. We argue that the spatial links as well as the spatial modes of the matter fields determine the boundaries separating regions where $Z_{N}$ symmetry is realised from rest of the phase diagram.
↳ hep-lathep-phnucl-thInt.J.Mod.Phys.A(2022)·2 citations
11
Axial meson exchange and the $Z_{c} (3900)$ and $Z_{cs} (3985)$ resonances as heavy hadron molecules
Mao-Jun Yan🇨🇳 · Fang-Zheng Peng🇨🇳 · Mario Sánchez Sánchez🇫🇷 · Manuel Pavon Valderrama🇨🇳
Early speculations about the existence of heavy hadron molecules were grounded on the idea that light-meson exchanges forces could lead to binding. In analogy to the deuteron, the light-mesons usually considered include the pion, sigma, rho and omega, but not the axial meson $a_{1} (1260)$ . Though it has been argued in the past that the coupling of the axial meson to the nucleons is indeed strong, its mass is considerably heavier than that of the vector mesons and thus its exchange ends up being suppressed. Yet, this is not necessarily the case in heavy hadrons molecules: we find that even though the contribution to binding from the axial meson is modest, it cannot be neglected in the isovector sector where vector meson exchange cancels out. This might provide a natural binding mechanism for molecular candidates such as the $Z_{c} (3900)$ , $Z_{c} (4020)$ or the more recently observed $Z_{cs} (3985)$ . However the $Z_{cs} (3985)$ is more dependent on a mixture of different factors, which (besides axial meson exchange) include $η$ exchange and the nature of scalar meson exchange. Together they point towards the existence of two $Z_{cs} (3985)$ -like resonances instead of one, while the observations about the role of scalar meson exchange in the $Z_{cs} (3985)$ might be relevant for the $P_{cs} (4459)$ . Finally, the combination of axial meson exchange and flavor symmetry breaking effects indicates that the isovector $J^{P C} = 0^{++}$ $D^{*} D ˉ^{*}$ and the strange $J^{P} = 2^{+}$ $D^{*} D ˉ_{s}^{*}$ molecules are the most attractive configurations and thus the most likely molecular partners of the $Z_{c} (3900)$ , $Z_{c} (4020)$ and $Z_{cs} (3985)$ .
↳ hep-phhep-exhep-latnucl-thPRD(2021)·57 citations
12
Charmed and bottomed hadronic cross sections from a statistical model
Gábor Balassa🇭🇺 · György Wolf🇭🇺
In this work, we extended our statistical model with charmed and bottomed hadrons, and fit the quark creational probabilities for the heavy quarks, using low energy inclusive charmonium and bottomonium data. With the finalized fit for all the relevant types of quarks (up, down, strange, charm, bottom) at the energy range from a few GeV up to a few tens of GeV's, the model is now considered complete. Some examples are also given for proton-proton, pion-proton, and proton-antiproton collisions with charmonium, bottomonium, and open charm hadrons in the final state.
↳ hep-phnucl-thEPJA(2020)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE