In this work, we explore the possible scenario of strange stars admixed with fermionic or bosonic dark matter. For the description of the “visible” sector, we use a specific phenomenological quark model that takes into account in-medium effects for the quark masses through a suitable baryonic density dependence in which the free parameters are chosen from the analysis of the stellar matter stability window (parametrizations presenting lower energy per baryon than iron nuclei). In the case of the dark sector, we investigate the predictions of fermionic and bosonic models. In the former, we consider a spin $1/2$ dark particle, and the latter is described by a dark scalar meson. Both models present a repulsive vector interaction, which is particularly important for the bosonic model since it helps avoid the collapse of the star due to the lack of degeneracy pressure. Our results point out possible stable strange star configurations in agreement with data from the NASA NICER measurements of the pulsars PSR $\mathrm{J}0030+0451$ and PSR $\mathrm{J}0740+6620$, including the latest observational data, as well as the observed HESS J1731-347 mass-radius relationship. As another feature, we find stars with dark matter halo configurations for lower values of the dark particle mass.

Recent simulations of wave dark matter around black hole binaries revealed the formation of a universal density profile that corotates with the binary. We derive this profile from first principles, interpreting it as the steady state of a scattering process. We find that the scattering becomes particularly efficient when the ratio of the binary separation to the dark matter’s de Broglie wavelength assumes certain discrete values, which can be interpreted as bound state resonances. After estimating the amount of dark matter that undergoes this type of scattering off supermassive black hole binaries at galactic centers, we demonstrate that the process can induce an observable modification of the slope of the pulsar timing array spectrum. This opens up a new possibility to gain insights on the nature of dark matter from observations of low-frequency gravitational waves.

In this work, we numerically explore the dynamics of a point mass (e.g., a stellar-mass black hole) moving within a thin accretion disk of a massive object (i.e., a supermassive black hole) with three dimensional hydrodynamical simulations using athena++. We are particularly interested in the regime that the Hill radius of the point mass is greater than the disk thickness, but the point mass is not sufficiently massive to open a “gap” in a high viscosity disk. This parameter regime may be seen for stellar-mass objects moving within thin accretion disks of massive black holes, but less studied for the planet migration scenario in protoplanetary disks. We find that the disk migration may be significantly slower than the type-I migration, depending on the surface density gradient of the disk. Furthermore, the circumsingle disk around the point mass plays an important role in damping the orbital eccentricity. If the gravitational interaction between the point mass and circumsingle disk material is turned off, the orbital eccentricity may be pumped to $\mathcal{O}({10}^{-2})$ level. Because space-borne gravitational wave detectors such as LISA (Laser Interferometer Space Antenna) are able to measure the eccentricity of extreme mass-ratio inspirals to the level of $\mathcal{O}({10}^{-5})$, this finding highlights the importance of understanding stellar-mass black hole feedback mechanisms which will modify the structures of the circumsingle disk, as they will impact LISA observables such as the eccentricity.

Very-high-energy ($E>100\mathrm{GeV}$) $\gamma$-ray observations offer the possibility of indirectly detecting the presence of axion-like particles (ALPs). This paper focuses on detecting photon-ALP oscillations in $\gamma$-ray spectra from distant sources in astrophysical magnetic fields. Strong evidence indicates that 1) photon-ALP oscillations can effectively decrease photon absorption at energies of several tens of TeV—caused by the extragalactic background light—to a level able to better explain the observational data, and 2) the impact of magnetic-field models in photon-ALP beams crossing several magnetized media is significant. We revisit the expected signature for the photon-ALP oscillation effects on $\gamma \text{−}\gamma$ absorption in the TeV spectra of Mrk 501. The result is that the photon-ALP beam propagation with mass $m_a\sim {10}^{-10}\mathrm{eV}$ and two-photon coupling constant $g_{a\gamma }\sim 0.417\times {10}^{-11}{\mathrm{GeV}}^{-1}$ crossing reasonable magnetic field scenarios considered here can roughly reproduce the observed TeV $\gamma$-ray spectra for Mrk 501.

Primordial black holes can be the entirety of the dark matter in a broad, approximately 5-orders-of-magnitude-wide mass range, the “asteroid mass range,” between ${10}^{-16}{M}_{\text{Sun}}$—where constraints originate from evaporation—and ${10}^{-11}{M}_{\text{Sun}}$—from microlensing. A direct detection in this mass range is very challenging with any known observational or experimental methods. Here we update the calculation of the sight distance for narrow-band detectors such as resonant microwave cavities and the resulting maximal event rate. We find that the largest detection rates are associated with binaries from nonmonochromatic mass functions in early-formed three-body systems. Even in the most optimistic setup, these events are anticipated to be extremely rare.

Future gravitational wave observatories can probe dark matter by detecting the dephasing in the waveform of binary black hole mergers induced by dark matter overdensities. Such a detection hinges on the accurate modeling of the dynamical friction, induced by dark matter on the secondary compact object in intermediate and extreme mass ratio inspirals. In this paper, we introduce nbodyimri, a new publicly available code designed for simulating binary systems within cold dark matter spikes. Leveraging higher particle counts and finer time steps, we validate the applicability of the standard dynamical friction formalism and provide an accurate determination of the maximum impact parameter of particles which can effectively scatter with a compact object, across various mass ratios. We also show that in addition to feedback due to dynamical friction, the dark matter also evolves through a stirring effect driven by the time-dependent potential of the binary. We introduce a simple semianalytical scheme to account for this effect and demonstrate that including stirring tends to slow the rate of dark matter depletion and therefore enhances the impact of dark matter on the dynamics of the binary.

Dark matter overdensities around black holes can alter the dynamical evolution of a companion object orbiting around it, and cause a dephasing of the gravitational waveform. Here, we present a refined calculation of the coevolution of the binary and the dark matter distribution, taking into account the accretion of dark matter particles on the companion black hole, and generalizing previous quasicircular calculations to the general case of eccentric orbits. These calculations are validated by dedicated $N$-body simulations. We show that accretion can lead to a large dephasing, and therefore cannot be neglected in general. We also demonstrate that dark matter spikes tend to circularize eccentric orbits faster than previously thought.

We investigate nonradial $f$-mode oscillations of hybrid neutron stars in full general relativity, employing hybrid equations of state describing a nuclear outer core and a pasta-phase transition to a quark-matter core. The validity of various universal relations is confirmed for those stars. Prospects of observations are also discussed.

Magnetic effects significantly contribute to errors in gravitational experiments. Typically, remanent magnetism is characterized by magnetic dipole interactions. However, this approach neglects higher-order magnetic terms, particularly the remanent magnetic quadrupole moment (RMQM) interaction, which may compromise experimental accuracy. This paper focuses on measuring the RMQM of a macroscopic mass to evaluate its impact. Measurements were performed using a rotating torsion pendulum equipped with custom-designed magnetic coils. The investigation examines two predominantly non-magnetic samples, one of which is an optimized pendulum specifically designed to test the equivalence principle. The results indicate that the RMQM components of interest for the pendulum have a magnitude of $3.7(3)\times {10}^{-11}\mathrm{A}·{\mathrm{m}}^3$. Given a reported magnetic field gradient of $0.1\mathrm{nT}/\mathrm{cm}$, the RMQM interaction can introduce a non-negligible correction at the ${10}^{-14}$ precision level in the equivalence principle test. For the second sample, the RMQM components of interest are measured to be $43.8(4)\times {10}^{-11}\mathrm{A}·{\mathrm{m}}^3$. The uncertainty is mainly due to statistical error and the coil installation error. This RMQM measurement could be similarly applied to other gravitational experiments if needed.

We implement a variational quantum algorithm to investigate the chiral condensate in a $1+1$ dimensional SU(2) non-Abelian gauge theory. The algorithm is evaluated using a proposed Monte Carlo sampling method, which allows the extension to large qubit systems. The obtained results through quantum simulations on classical and actual quantum hardware are in good agreement with exact diagonalization of the lattice Hamiltonian, revealing the phenomena of chiral symmetry breaking and restoration as functions of both temperature and chemical potential. Our findings underscore the potential of near-term quantum computing for exploring QCD systems at finite temperature and density in non-Abelian gauge theories.

In the paper, we derive the $\xi$ moments $⟨{\xi }_{2;b_1}^{n;\parallel }⟩$ of the longitudinal leading-twist distribution amplitude ${\varphi }_{2;b_1}^{\parallel }$ for the ${}^1{P}_1$-state $b_1(1235)$ meson by using the QCD sum rules under the background field theory. Considering the contributions from the vacuum condensates up to dimension six, its first two nonzero $\xi$ moments at the scale 1 GeV are $⟨{\xi }_{2;b_1}^{1;\parallel }⟩=-0.647_{-0.113}^{+0.118}$ and $⟨{\xi }_{2;b_1}^{3;\parallel }⟩=-0.328_{-0.052}^{+0.055}$, respectively. Using those moments, we then fix the Gegenbauer expansion series of ${\varphi }_{2;b_1}^{\parallel }$ and apply it to calculate $B\to b_1(1235)$ transition form factors (TFFs) that are derived by using the QCD light-cone sum rules. Those TFFs are then extrapolated to the physically allowable $q^2$ range via the simplified series expansion. As for the branching fractions, we obtain $\mathcal{B}({\overline{B}}^0\to b_1(1235{)}^{+}{e}^{-}{\overline{\nu }}_e)=2.179_{-0.422}^{+0.553}\times {10}^{-4}$, $\mathcal{B}(B^0\to b_1(1235{)}^{-}{\mu }^{+}{\nu }_{\mu })=2.166_{-0.415}^{+0.544}\times {10}^{-4}$, $\mathcal{B}(B^{+}\to b_1(1235{)}^0{e}^{+}{\nu }_e)=2.353_{-0.456}^{+0.597}\times {10}^{-4}$, and $\mathcal{B}(B^{+}\to b_1(1235{)}^0{\mu }^{+}{\nu }_{\mu })=2.339_{-0.448}^{+0.587}\times {10}^{-4}$, respectively.

We explore various ${\mathrm{\Lambda }}_c$ states, including ${\mathrm{\Lambda }}_c$, ${\mathrm{\Lambda }}_c(2595)$, ${\mathrm{\Lambda }}_c(2940)$, and the predicted $(\overline{D}N)$ hadronic molecular states, in photoproduction and electroproduction to estimate their yields at the EicC and EIC. Assuming ${\mathrm{\Lambda }}_c(2940)$ as either a hadronic molecular state or a three-quark state, our analysis demonstrates that its production rates are of the same order of magnitude, posing challenges in identifying its underlying structure. After considering the integral luminosity, the yields of ${\mathrm{\Lambda }}_c$ excited states reach ${10}^6$ to ${10}^7$ at the EicC and EIC. The $(\overline{D}N)$ molecular states with both isospin $I=0$ and $I=1$ are also studied, with yields reaching ${10}^5$, making them likely to be detectable at these facilities.

The semileptonic $B_{(s)}\to T(J^P=2^{-})l^{+}{l}^{-}$ decays induced by flavor changing neural currents are investigated within the light cone quantum chromodynamics (QCD) sum rule method in the leading order of $O({\alpha }_s)$. We apply the $B$ meson distribution amplitudes up to twist-4 and calculate the relevant form factors of the $B_{(s)}\to T$ transitions, where $T=K_2,a_2,f_2,{\varphi }_2$ with $J^P=2^{-}$. The obtained results of the form factors then adopted in the calculations of the corresponding widths. The present results can be used in future experiments for studying the properties of $J^P=2^{-}$ tensor mesons.

We introduce a novel search strategy for heavy top-philic resonances that induce new contributions to four-top production at the LHC. We capitalize on recent advances in top-tagging performance to demonstrate that the final state, that is expected to be boosted based on current limits, can be fully reconstructed and exploited. Notably, our approach promises bounds on new physics cross sections that are a few to 60 times stronger than those obtained with existing searches, showcasing its unprecedented effectiveness in probing top-philic new physics.

New gauge bosons coupled to heavy neutral leptons (HNLs) are simple and well-motivated extensions of the Standard Model. In searches for HNLs in proton fixed-target experiments, we find that a large population of gauge bosons ($Z^{\prime }$) produced by proton bremsstrahlung may decay to HNLs, leading to a significant improvement in existing bounds on the ($m_{\mathrm{HNL}},U_{\alpha }$), where $U_{\alpha }$ represent the mixing between HNL and the active neutrinos with flavor $\alpha$. We study this possibility in fixed target experiments with the 8 GeV proton beams, including SBND, MicroBooNE, and ICARUS, as well as DUNE and DarkQuest at 120 GeV. We find the projected sensitivities to additional $Z^{\prime }$-mediated HNL production can bring the seesaw mechanism of the neutrino masses within a broadened experimental reach.

We study the kinetic cooling (heating) of old neutron stars due to coherent scattering with relic neutrinos (sterile neutrino dark matter) via Standard Model neutral-current interactions. We take into account several important physical effects, such as coherent enhancement, gravitational clustering, neutron degeneracy, Pauli blocking and weak potential. We find that the anomalous cooling of neutron stars due to relic neutrino scattering is difficult to observe. However, the anomalous heating of neutron stars due to coherent scattering with keV-scale sterile neutrino dark matter may be observed by current and future telescopes operating in the optical to near-infrared frequency band, such as the James Webb Space Telescope (JWST), which would probe hitherto unexplored parameter space in the sterile neutrino mass-mixing plane.

The dynamics of cosmic reheating, that is, on how the energy stored in the inflaton is transferred to the standard model (SM) thermal bath, is largely unknown. In this work, we show that the phenomenology of the nonbaryonic dark matter (DM) ultraviolet freeze-in production strongly depends on the dynamics of the cosmic-reheating era. Using a general parametrization for the Hubble expansion rate, and SM temperature, we thoroughly investigate DM production during reheating, not only recovering earlier findings that focused on specific cases but also exploring alternative scenarios. Additionally, we derive a generalized framework for DM production via inflaton decays and identify the viable parameter space, while simultaneously addressing constraints from cosmic microwave background observations. As illustrative examples, we explore gravitational DM production through scatterings of SM particles or inflatons, deriving well-defined parameter regions for these scenarios.

Neutrinoless double-beta ($0\nu \beta \beta$) decay is an as-yet unobserved nuclear process, which stands to provide crucial insights for model building beyond the Standard Model of particle physics. Its detection would simultaneously confirm the hypothesis that neutrinos are Majorana fermions, thus violating lepton-number conservation, and provide the first measurement of the absolute neutrino mass scale. This work aims to improve the estimation within chiral effective field theory of the so-called “contact term” for $0\nu \beta \beta$ decay, a short-range two-nucleon effect that is unaccounted for in traditional nuclear approaches to the process. We conduct a thorough review of the justifications for this contact term and the most precise computation of its size to date [$g_{\nu }^{NN}=1.3(6)$ at renormalization point $\mu =m_{\pi }$], whose precision is limited by a truncation to elastic intermediate hadronic states. We then perform an extension of this analysis to a subleading class of inelastic intermediate states that we characterize, delivering an updated figure for the contact coefficient [$g_{\nu }^{NN}=1.4(3)$ at $\mu =m_{\pi }$] with uncertainty reduced by half. Such ab initio nuclear results, especially with enhanced precision, show promise for the resolution of disagreements between estimates of $0\nu \nu \beta \beta$ from different many-body methods.