Nuclear Theory·nucl-th

Friday·February 4, 2022

10 papers—1 primary·9 cross-listed

02
Anisotropic magnetized neutron star
Gholam Hossein Bordbar · Mohammad Karami
As we know, the effect of strong magnetic field causes the anisotropy for the magnetized compact objects. Therefore, in this paper, we have studied the structure properties of anisotropic case of magnetized neutron star. We have derived the equation of state (EoS) of neutron star matter for two forms of magnetic fields, one uniform and one density dependent. We have solved the generalized Tolman Oppenheimer Volkoff equations to examine the maximum mass and corresponding radius, Schwarzschild radius, graviitational redshift, Kretschmann scalar, and Buchdahl theorem for this system. It was shown that the maximum mass and radius of neutron star are increasing functions of the magnetic field. Also redshift, strength of gravity, and Kretschmann scalar increase as the magnetic field increases. In addition, the dynamical stability of anisotrop neutron star has been investigated, and finally a comparison with the empirical results has been made.
↳ gr-qcnucl-thEPJC(2022)·25 citations
03
Uncovering a chirally suppressed mechanism of $0 ν β β$ decay with LHC searches
Michael L. Graesser🇺🇸 · Gang Li🇺🇸 · Michael J. Ramsey-Musolf🇺🇸 · Tianyang Shen🇺🇸 · Sebastián Urrutia-Quiroga🇺🇸
$Δ L = 2$ lepton number violation (LNV) at the TeV scale could provide an alternative interpretation of positive signal(s) in future neutrinoless double beta $(0 ν β β)$ decay experiments. An interesting class of models from this point of view are those that at low energies give rise to dimension-9 vector operators and a dimension-7 operator, both of whose $0 ν β β$ -decay rates are "chirally suppressed". We study and compare the sensitivities of $0 ν β β$ -decay experiments and LHC searches to a simplified model in this class of TeV-scale LNV that is also $S U (2)_{L} \times U (1)_{Y}$ gauge invariant. The searches for $0 ν β β$ decay, which are here diluted by a chiral suppression of the vector operators, are found to be less constraining than LHC searches whose reach is increased by the assumed kinematic accessibility of the mediator particles. For the chirally suppressed dimension-7 operator generated by TeV-scale mediators, in contrast, $0 ν β β$ -decay searches place strong constraints on the size of the new Yukawa coupling. Signals of this model at the LHC and $0 ν β β$ -decay experiments are entirely uncorrelated with the observed neutrinos masses, as these new sources of LNV give negligible contributions to the latter. We find the prospects for the high-luminosity LHC and ton-scale $0 ν β β$ -decay experiments to uncover the chirally-suppressed mechanism with TeV-scale LNV to be promising. We also comment on the sensitivity of the $0 ν β β$ -decay lifetime to certain unknown low-energy constants that in the case of dimension-9 {\it scalar} operators are expected to be large due to non-perturbative renormalization.
↳ hep-phhep-exnucl-exnucl-thJHEP(2022)·17 citations
04
Quasi-normal g-modes of neutron stars with quarks
Tianqi Zhao🇺🇸 · Constantinos Constantinou🇮🇹 · Prashanth Jaikumar🇺🇸 · Madappa Prakash🇺🇸
Quasi-normal oscillation modes of neutron stars provide a means to probe their interior composition using gravitational wave astronomy. We compute the frequencies and damping times of composition-dependent core g-modes of neutron stars containing quark matter employing linearized perturbative equations of general relativity. We find that ignoring background metric perturbations due to the oscillating fluid, as in the Cowling approximation, underestimates the g-mode frequency by up to 10% for higher mass stars, depending on the parameters of the nuclear equation of state and how the mixed phase is constructed. The g-mode frequencies are well-described by a linear scaling with the central lepton (or combined lepton and quark) fraction for nucleonic (hybrid) stars. Our findings suggest that neutron stars with and without quarks are manifestly different with regards to their quasi-normal g-mode spectrum, and may thus be distinguished from one another in future observations of gravitational waves from merging neutron stars.
↳ gr-qcastro-ph.HEastro-ph.SRnucl-thPRD(2022)·49 citations
05
Universal tetramer and pentamer in two-dimensional fermionic mixtures
Ruijin Liu · Cheng Peng · Xiaoling Cui
We study the emergence of universal tetramer and pentamer bound states in the two-dimensional $(N + 1)$ system, which consists of $N$ identical heavy fermions interacting with a light atom. We show that the critical heavy-light mass ratio to support a ( $3 + 1$ ) tetramer below the trimer threshold is $3.38$ , and to support a ( $4 + 1$ ) pentamer below the tetramer threshold is $5.14$ . While these ground state tetramer and pentamer are both with zero total angular momentum, they exhibit very different density distributions and correlations in momentum space, due to their distinct angular momentum decompositions in the dimer-fermion frame. These universal bound states can be accessible by a number of Fermi-Fermi mixtures now realized in cold atoms laboratories, which also suggest novel few-body correlations dominant in their corresponding many-body systems.
↳ cond-mat.quant-gasnucl-thPRL(2022)·10 citations
06
Lattice QCD calculation of the two-photon exchange contribution to the muonic-hydrogen Lamb shift
Yang Fu🇨🇳 · Xu Feng🇨🇳 · Lu-Chang Jin🇺🇸 · Chen-Fei Lu🇨🇳
We develop a method for lattice QCD calculation of the two-photon exchange contribution to the muonic-hydrogen Lamb shift. To demonstrate its feasibility, we present the first lattice calculation with a gauge ensemble at $m_{π} = 142$ MeV. By adopting the infinite-volume reconstruction method along with an optimized subtraction scheme, we obtain $Δ E_{TPE} = - 28.9 (4.9) μ eV + 93.72 μ eV / fm^{2} \cdot ⟨ r_{p}^{2} ⟩$ , or $Δ E_{TPE} = 37.4 (4.9) μ$ eV, which is consistent with the previous theoretical results in a range of 20-50 $μ$ eV.
↳ hep-lathep-phnucl-thPRL(2022)·25 citations
07
Formulating bulk viscosity for neutron star simulations
T. Celora🇬🇧 · I. Hawke🇬🇧 · P. C. Hammond🇬🇧 · N. Andersson🇬🇧 · G. L. Comer🇺🇸
In order to extract the precise physical information encoded in the gravitational and electromagnetic signals from powerful neutron-star merger events, we need to include as much of the relevant physics as possible in our numerical simulations. This presents a severe challenge, given that many of the involved parameters are poorly constrained. In this paper we focus on the role of nuclear reactions. Combining a theoretical discussion with an analysis connecting to state-of-the-art simulations, we outline multiple arguments that lead to a reactive system being described in terms of a bulk viscosity. The results demonstrate that in order to properly account for nuclear reactions, future simulations must be able to handle different regimes where rather different assumptions/approximations are appropriate. We also touch upon the link to models based on the large-eddy-strategy required to capture turbulence.
↳ astro-ph.HEgr-qchep-phnucl-thPRD(2022)·41 citations
08
NCQ scaling of $f_{0} (980)$ elliptic flow in 200 GeV Au+Au collisions by STAR and its constituent quark content
Jie Zhao (for the STAR collaboration)🇺🇸
Searching for exotic state particles and studying their properties have furthered our understanding of quantum chromodynamics (QCD). The $f_{0}$ (980) resonance is an exotic state with relatively high production rate in relativistic heavy-ion collisions, decaying primarily into $π π$ . Currently, the structure and quark content of the $f_{0}$ (980) are unknown with several predictions from theory being a $q q$ state, a $q q q q$ state, a $K K$ molecule state, or a gluonium state. We report the first $f_{0}$ (980) elliptic flow ( $v_{2}$ ) measurement from 200 GeV Au+Au collisions at STAR. The transverse momentum dependence of $v_{2}$ is examined and compared to those of other hadrons (baryons and mesons). The empirical number of constituent quark (NCQ) scaling is used to investigate the constituent quark content of $f_{0}$ (980), which may potentially address an important question in QCD.
↳ nucl-exhep-exhep-phnucl-thEPJ Web Conf.(2022)·1 citation
09
Constraints on the merging binary neutron star mass distribution and equation of state based on the incidence of jets in the population
O. S. Salafia🇮🇹 · A. Colombo🇮🇹 · F. Gabrielli🇮🇹 · I. Mandel🇦🇺
A relativistic jet has been produced in the single well-localised binary neutron star (BNS) merger detected to date in gravitational waves (GWs), and the local rates of BNS mergers and short gamma-ray bursts are of the same order of magnitude. This suggests that jet formation is not a rare outcome for BNS mergers, and we show that this intuition can be turned into a quantitative constraint: at least about $1/3$ of GW-detected BNS mergers, and at least about $1/5$ of all BNS mergers, should produce a successful jet (90\% credible level). Whether a jet is launched depends on the properties of the merger remnant and of the surrounding accretion disc, which in turn are a function of the progenitor binary masses and equation of state (EoS). The incidence of jets in the population therefore carries information about the binary component mass distribution and EoS. Under the assumption that a jet can only be produced by a black hole remnant surrounded by a non-negligible accretion disc, we show how the jet incidence can be used to place a joint constraint on the space of BNS component mass distributions and EoS. The result points to a broad mass distribution, with particularly strong support for masses in the $1.3 - 1.6 M_{⊙}$ range. The constraints on the EoS are shallow, but we show how they will tighten as the knowledge on the jet incidence improves. We also discuss how to extend the method to include future BNS mergers, with possibly uncertain jet associations.
↳ astro-ph.HEgr-qcnucl-thAstron.Astrophys.(2022)·28 citations
10
Neutrino Astronomy with IMB, Kamiokande and Super Kamiokande
John M. LoSecco🇺🇸
Some of the earliest work on neutrino astronomy was accomplished by a class of underground detectors primarily designed for particle physics goals . These detectors used inexpensive water to obtain the large masses needed to observe the very low interaction rates expected from neutrinos. They exploited the relatively large light attenuation length and the index of refraction of the water to get a very inexpensive cost per thousand tons of detector. The results obtained from these pioneering neutrino detectors have included real time observation of solar neutrinos, supernova neutrinos, and atmospheric neutrinos. Searches for neutrino point sources, dark matter and primordial magnetic monopoles were also made using them.
↳ astro-ph.HEhep-exhep-thnucl-ex+10 citations

Affiliations

first authorsco-authorsvia INSPIRE