We outline two important effects that are missing from most evaluations of the dark matter capture rate in neutron stars. As dark matter scattering with nucleons in the star involves large momentum transfer, nucleon structure must be taken into account via a momentum dependence of the hadronic form factors. In addition, due to the high density of neutron star matter, we should account for nucleon interactions rather than modeling the nucleons as an ideal Fermi gas. Properly incorporating these effects is found to suppress the dark matter capture rate by up to four orders of magnitude for the heaviest stars.
We calculate the properties of neutron matter and highlight the physics of chiral three-nucleon forces. For neutrons, only the long-range 2 pi-exchange interactions of the leading chiral three-nucleon forces contribute, and we derive density-dependent two-body interactions by summing the third particle over occupied states in the Fermi sea. Our results for the energy suggest that neutron matter is perturbative at nuclear densities. We study in detail the theoretical uncertainties of the neutron matter energy, provide constraints for the symmetry energy and its density dependence, and explore t…
Enhanced Neutrino Cooling from Parity-Doubled Nucleons in Neutron Star Cooling Simulations
Catholic Institute of Technology（天主教理工学院）；Universidade Federal Fluminense（弗鲁米嫩塞联邦大学）；ICRANet（国际相对论天体物理中心网络）；Washington University in St. Louis（圣路易斯华盛顿大学）；Frankfurt Institute for Advanced Studies (FIAS)（法兰克福高等研究所）；GSI Helmholtzzentrum für Schwerionenforschung GmbH（德国重离子研究中心）；Kent State University（肯特州立大学）；Brookhaven National Laboratory（布鲁克海文国家实验室）
In order to reveal the difference between the latest neutron star observation experiment GW170817 and the existing theory, we mainly consider the effect of the nucleon radius on the neutron star from the existing theory. We believe that the effect of nucleon radius in neutron star is not negligible, and the mass radius of nucleon should be used instead of the charge radius. The nucleon mass radius is set as $r_m = 0.55\pm0.09$ fm from the new measurements. It is considered as an input to the "Excluded Volume Effects" model in the equation of state of nuclear matter. We propose a novel neutron …
We calculate the differential scattering rate for thermal neutrinos in a hot and dilute gas of interacting neutrons using linear response theory. The dynamical structure factors for density and spin fluctuations of the strongly interacting neutron matter, expected in the neutrino decoupling regions of supernovae and neutron star mergers, are calculated in the virial expansion for the first time. Correlations due to nucleon-nucleon interactions are taken into account using a pseudo-potential that reproduces measured nucleon-nucleon phase shifts, and we find that attractive s-wave interactions e…
Various kinds of isovector nucleon effective masses are used in the literature to characterize the momentum/energy dependence of the nucleon symmetry potential or self-energy due to the space/time non-locality of the underlying isovector strong interaction in neutron-rich nucleonic matter. The multifaceted studies on nucleon isovector effective masses are multi-disciplinary in nature. Besides structures, masses and low-lying excited states of nuclei as well as nuclear reactions, studies of the isospin dependence of short-range correlations in nuclei from scatterings of high-energy electrons an…
We calculate the rate of production of hypothetical light vector bosons (LVBs) from nucleon-nucleon bremsstrahlung reactions in the soft radiation limit directly in terms of the measured nucleon-nucleon elastic cross sections. We use these results and the observation of neutrinos from supernova SN1987a to deduce constraints on the couplings of vector bosons with masses $\lesssim 200$ MeV to either electric charge (dark photons) or to baryon number. We establish for the first time strong constraints on LVB that couple only to baryon number, and revise earlier constraints on the dark photon. For…
In this contribution, we summarize our recent studies on the chiral invariant mass and the chiral condensates in neutron star matter. We construct a unified equations of state assuming the crossover phase transition from hadronic matter described by a parity doublet model to quark matter by an Nambu--Jona-Lasinio type quark model. We first show that the chiral invariant mass is constrained to be 600 MeV $\lesssim m_0 \lesssim$ 900 MeV from recent observations of neutron stars. We then determine the density dependence of the chiral condensate in the crossover description, and show that the chir…
The QCD axion is a hypothetical particle motivated by the Strong CP problem of particle physics. One of the primary ways in which its existence can be inferred is via its function as an additional cooling channel in stars, with some of the strongest constraints coming from the supernova observation SN1987A. Multimessenger observations of binary neutron star mergers (such as those of GW170817, AT2017gfo, and GRB170817A) may provide another scenario in which such constraints could be obtained. In particular, the axion could potentially alter the lifetime, the ejection of material, and the emitte…
We discuss the dark gauge boson emission from neutron stars via nucleon-nucleon bremsstrahlung. Through the rigorous treatment of the effective field theory prescription and the thermal effect, we derive the relevant couplings of dark gauge bosons to hadrons in medium. As a specific example, the $U(1)_{\rm B-L}$ gauge boson scenario is chosen to investigate dark gauge boson emissivities during supernovae and cooling of young neutron stars. From the stellar cooling argument, we obtain the constraints on the $\rm B-L$ gauge coupling for given gauge boson masses in two observations: the duration …
We study the interplay between charge symmetry breaking and renormalization in the NN system for s-waves. We find a set of universality relations which disentangle explicitly the known long distance dynamics from low energy parameters and extend them to the Coulomb case. We analyze within such an approach the One-Boson-Exchange potential and the theoretical conditions which allow to relate the proton-neutron, proton-proton and neutron-neutron scattering observables without the introduction of extra new parameters and providing good phenomenological success.
We investigate the parity-violating analyzing power in neutron capture on the proton at thermal energies in the framework of chiral effective field theory. By combining this analysis with a previous analysis of parity violation in proton-proton scattering, we are able to extract the size of the weak pion-nucleon coupling constant. The uncertainty is significant and dominated by the experimental error which is expected to be reduced soon.
I compare the non-relativistic effective theory of one-body dark matter-nucleon interactions to current dark matter direct detection experiments and neutrino telescope observations, presenting exclusion limits on the coupling constants of the theory. In the analysis of direct detection experiments, I focus on the interference of different dark matter-nucleon interaction operators and on predictions observable at directional detectors. Interpreting neutrino telescope observations, I use new nuclear response functions recently derived through nuclear structure calculations and show that hydrogen…
Neutron stars generally cools off by the emission of gamma rays and neutrinos. But axions can also be produced inside a neutron star by the process of nucleon-nucleon axion bremsstrahlung. The escape of these axions adds to the cooling process of neutron star. We explore the nature of cooling of neutron stars including the axion emission and compare our result with the scenario when the neutron star is cooled by only the emission of gamma rays and neutrinos. In our calculations we consider both the degenerate and non-degenerate limits for such axion energy loss rate and the resulting variation…
We survey the current status of understanding of pairing and superfluidity of neutrons and protons in neutron stars from a theoretical perspective, with emphasis on basic physical properties. During the past two decades, the blossoming of the field of ultracold atomic gases and the development of quantum Monte Carlo methods for solving the many-body problem have been two important sources of inspiration, and we shall describe how these have given insight into neutron pairing gaps. The equilibrium properties and collective oscillations of the inner crust of neutron stars, where neutrons paired …
Neutron structure function $F_2^n(x)$ from deep inelastic electron scattering off few-nucleon systems
研究了从氘核、$^{3}He$和$^{3}H$的深部非弹性结构函数的联合测量中可靠地提取$ x < 0.85$的中子深部非弹性结构函数$F_2^n(x)$的可能性。如果适当考虑原子核结构的影响，这种提取中的模型依赖性，与原子核中核子之间可能的不同相互作用有关，被证明是弱的。提出了一个联合分析的深非弹性结构函数的这些核研究的影响超出了脉冲近似。
We improve limits on the spin-independent scattering cross section of Dark Matter on nucleons, for DM in the 300 MeV -- 100 GeV mass range, based on the DAMIC and XQC experiments. Our results close the window which previously existed in this mass range, for a DM-nucleon cross section of order $\approx μ$b, assuming the standard velocity distribution.
Neutrino Bremsstrahlung in Neutron Matter from Effective Nuclear Interactions
我们重新讨论了中子-中子散射中中微子对韧致辐射的发射率，nn -> nn nu nubar，这是由Friman和Maxwell从包含关联效应的一π交换势计算的。从自由空间低动量核子-核子相互作用V_{low k}出发，考虑了张量、自旋轨道和二阶介质诱导的非中心效应对中子物质散射振幅的贡献。我们发现核子-核子相互作用的屏蔽降低了密度低于核物质密度的中微子韧致辐射的发射率。我们讨论了介质修改的影响，通过中微子发射冷却的中子星，考虑到最近的结果极化效应的中子超流性。
The existence of stars with a large mass of 2 solar masses means that the equation of state is stiff enough to provide high enough pressure at large central densities. Previous work shows that such a stiff equation of state is possible if the ground state has nucleons as its constituents. We find this to be so in a chiral soliton ( skyrmion ) model for a composite nucleon which has bound state quarks. The strong binding of the quarks in this composite nucleon is plausibly the origin of the nucleon-nucleon hard core. In this model we find a new state of superdense matter at high density which i…
We investigate kaon photoproduction off the neutron target, i.e., $γn \to K^0 Λ$, focusing on the role of nucleon resonances given in the Review of Particle Data Group in the range of $\sqrt{s} \approx 1600 - 2200$ MeV. We employ an effective Lagrangian method and a Regge approach. The strong couplings of nucleon resonances with $KΛ$ vertices are constrained by quark model predictions. The numerical results of the total and differential cross sections are found to be in qualitative agreement with the recent CLAS and FOREST experimental data. We discuss the effects of the narrow nucleon resonan…
We investigate $η$ photoproduction off the neutron target, i.e., $γn \to ηn$, employing an effective Lagrangian method combining with a Regge approach. As a background, we consider nucleon exchange in the $s$-channel diagram and $ρ$- and $ω$-meson Regge trajectories in the $t$ channel. The role of nucleon resonances given in the Review of Particle Data Group in the range of $W \approx 1500 - 2100$ MeV and the narrow nucleon resonance $N(1685,1/2^+)$ is extensively studied. The numerical results of the total and differential cross sections, double polarization observable $E$, and helicity-depen…
Non-relativistic dark matter scattering with nucleons is constrained by direct detection experiments. We use the XENON constraints on the spin-independent and spin-dependent cross section for dark matter scattering with nucleons to constrain a hypothetical Majorana fermionic dark matter particle's couplings to the Higgs boson and Z boson. In the procedure we illustrate the change in the dark matter nucleon cross section as one goes from non-relativistic, coherent scattering to relativistic, incoherent scattering. While the Z invisible decay width excludes directly couplings of dark matter to o…
By employing a recently constructed hyperon-nucleon potential the equation of state of β-equilibrated and charge neutral nucleonic matter is calculated. The hyperon-nucleon potential is a low-momentum potential which is obtained within a renormalization group framework. Based on the Hartree-Fock approximation at zero temperature the densities at which hyperons appear in neutron stars are estimated. For several different bare hyperon-nucleon potentials and a wide range of nuclear matter parameters it is found that hyperons in neutron stars are always present. These findings have profound conseq…
Celestial objects such as stars and planets might be able to capture a large amount of dark matter particles through dark matter-nucleon scattering. Many previous studies have considered different celestial objects such as the Sun and the Earth as natural dark matter detectors and obtained some stringent bounds of the dark matter-nucleon scattering cross section. In this study, we use the $\sim 10$ MeV electron neutrino flux limits obtained by the Super-Kamiokande experiment and consider the Earth as a large natural dark matter detector to constrain the dark matter-nucleon scattering cross sec…
Background: Deep-inelastic scattering (DIS) on the deuteron with spectator nucleon tagging represents a unique method for extracting the free neutron structure functions and exploring the nuclear modifications of bound protons and neutrons. The detection of the spectator (with typical momenta $\lesssim$ 100 MeV/c in the deuteron rest frame) controls the nuclear configuration during the DIS process and enables a differential analysis of nuclear effects. At the future electron-ion collider (EIC) such measurements will be performed using far-forward detectors. Purpose: Simulate deuteron DIS with …
After scattering off nuclei in the Sun, dark matter particles can be gravitationally captured by the Sun, accumulate in the Sun's core and annihilate into Standard Model particles. Neutrinos originating from these annihilations can be detected by the IceCube Neutrino Observatory, located at the South Pole. Due to the non-observation of these neutrinos, constraints on the standard spin-dependent and spin-independent dark matter-nucleon scattering cross sections have been placed. Based on these constraints, we present upper limits on the coupling constants of the non-relativistic effective theor…
We present a method to derive conservative upper limits on the coupling constants of the effective theory of dark matter-nucleon interactions, taking into account the interference among operators. The method can be applied in any basis, and can be easily particularized to any UV complete model. To illustrate our method, we use the IceCube constraints on an exotic neutrino flux from dark matter annihilations in the Sun to derive conservative upper limits on the dark matter-nucleon coupling constants of the effective theory, as well as to derive conservative upper limits on the dark matter-proto…
Within the standard V - A theory of weak interactions, Quantum Electrodynamics (QED) and the linear sigma-model (LsM) of strong low-energy hadronic interactions we analyse gauge and infrared properties of hadronic structure of the neutron and proton in the neutron beta decay to leading order in the large nucleon mass expansion. We show that the complete set of Feynman diagrams describing radiative corrections of order O(α/π), induced by hadronic structure of the nucleon, to the rate of the neutron beta decay is gauge non-invariant and unrenormalisable. We show that a gauge non-invariant contri…
The Split SUSY scenario with light Higgsino states is treated as an application to the Dark Matter problem. We have considered the structure of the neutralino-nucleon interaction and calculated cross-section of the neutralino-nucleon scattering. The decay properties of the lightest chargino and next lightest neutralino are analyzed in details.
The consequences of a flavor broken SU(3)_f dynamical parton model are studied in the context of the elastic scattering of supersymmetric dark matter off nucleons. It is shown that the predictions of this model differ considerably from those of the commonly applied `standard' parton model. Some notable properties of the dynamical parton model are finally presented and discussed.
We investigate an asymmetry in the angular distribution of hard elastic proton-neutron scattering with respect to 90deg center of mass scattering angle. We demonstrate that the magnitude of the angular asymmetry is related to the helicity-isospin symmetry of the quark wave function of the nucleon. Our estimate of the asymmetry within the quark-interchange model of hard scattering demonstrates that the quark wave function of a nucleon based on the exact SU(6) symmetry predicts an angular asymmetry opposite to that of experimental observations. On the other hand the quark wave function based on …
Within the standard V - A theory of weak interactions, Quantum Electrodynamics (QED) and the linear sigma-model (LsM) of strong low-energy hadronic interactions we analyse infrared properties of hadronic structure of the neutron and proton in the neutron beta decays to leading order in the large nucleon mass expansion. We confirm validity and high confidence level of contributions of hadronic structure of the nucleon to the radiative corrections, calculated by Sirlin (Phys. Rev. 164, 1767 (1967)) to leading order in the large nucleon mass expansion. At the level of order 10^{-5} relative to Si…
We present lattice QCD simulation results from the European Twisted Mass Collaboration (ETMC) for the light, strange and charm quark contents of the nucleon. These quantities are important ingredients to estimate the cross-section for the detection of WIMPs as Dark Matter candidates. By employing a particular lattice QCD formulation, i.e. twisted mass fermions, accurate results of the light and strange scalar contents of the nucleon can be obtained. In addition, we provide a bound for the charm quark content of the nucleon.
