We study the prospects of detecting dark matter coupled to the spin of the electron, such that it may scatter and excite magnons—collective excitations of electronic spins. We show that materials exhibiting long-range magnetic order where the spins are coupled only along a plane may act as directional dark matter detectors. These quasi-two-dimensional materials possess anisotropic dispersion relations and structure functions which induce a sidereal modulation in the excitation rate. We calculate the expected signal rate for some candidate (anti)ferromagnets, demonstrating a possible route to the direct detection of spin-dependent dark matter in the keV to MeV mass range.

The Large Hadron Collider precision measurement of $h_{125}$ properties suggests that a misaligned two-Higgs-doublet model (2HDM) type I is preferred among other types of the model. In this analysis, a lepton collider potential for charged Higgs boson observation is evaluated and compared with HL-LHC expectations. We focus on $H^{\pm }\to W^{\pm }{h}_{125}$ decay which is exclusively activated in misaligned scenario. An event analysis including fast detector simulation is performed, and it is shown that some parts of the parameter space which are out of HL-LHC reach can be probed by a high-energy lepton collider with signal significance exceeding $2\sigma$ and $5\sigma$ for exclusion or discovery. The region with highest sensitivity is in the middle range charged Higgs boson mass, i.e., $350<m_{H^{\pm }}<450\mathrm{GeV}$ and $\tan \beta \gtrsim 4$ at nonzero $\cos (\beta -\alpha )$ values.

The axionlike particle (ALP) and primordial black hole (PBH) are two representative dark matter (DM) candidates as light bosonic DM and macroscopic objects, respectively. In this work, we investigate the gamma-ray production mechanisms induced by PBH evaporation and ALP-photon coupling $g_{a\gamma \gamma }$. The detection of gamma rays is also explored in future satellite telescopes, including AMEGO, e-ASTROGAM, and MAST. We first propose the evaporation-conversion scenario in which light ALPs are emitted by PBHs and are converted into photons in the presence of magnetic field in the Universe. The second scenario assumes ALPs as a dominant DM component in the Milky Way and considers the relativistic electron production from PBH evaporation. The emitted electrons scatter off nonrelativistic ALP in DM halo and produce gamma rays through the ALP-photon coupling. Using the Fisher forecasting method, we calculate the gamma-ray energy spectra from these two scenarios and derive projected sensitivity for the fraction of DM composed of PBHs $f_{\mathrm{PBH}}$ and ALP-photon coupling $g_{a\gamma \gamma }$.

Neutrino self-interaction with a larger “Fermi constant” is often resorted to for understanding various puzzles of our Universe. We point out that a light, neutrinophilic scalar particle $\varphi$ through radiative correction leads to an energy-scale dependence in the neutrino-$Z$-boson gauge coupling. The driver behind this phenomenon is a large separation between the mass scales of $\varphi$ and additional heavy particles needed for gauge invariance. This is a generic effect insensitive to details of the UV completion. We show that the running can change the $Z\nu \overline{\nu }$ coupling by several percent and affect the measurement of weak mixing angle through neutrino neutral-current processes. We discuss the interplay between the running of the $Z\nu \overline{\nu }$ coupling and ${\sin }^2{\theta }_W$ in various experimental observables. It is possible to disentangle the two effects with more than one precise measurement.

We study a scale invariant inverse seesaw model that radiatively generates the electroweak scale, the Standard Model (SM) neutrino masses, and stabilizes the electroweak vacuum. Previous studies have noted that the SM Higgs potential and the electroweak scale can be radiatively generated via the minimal seesaw mechanism. This scenario, called the “neutrino option,” was UV completed by a scale invariant framework. However, these models predict singlet neutrino and scalar masses at ${10}^7–{10}^9\mathrm{GeV}$, beyond any experimental reach and leave the electroweak vacuum metastable/unstable at high energies. In this work, we propose modifications to this framework that lower the singlet neutrino masses to experimentally accessible scales through an inverse seesaw mechanism, while fully stabilizing the electroweak vacuum with an additional singlet scalar. The possibility of generating the observed baryon asymmetry of the Universe via leptogenesis is also explored.

We theoretically investigate the Casimir effect originating from Dirac fields in finite-density matter under a magnetic field. In particular, we focus on quark fields in the magnetic dual chiral density wave phase as a possible inhomogeneous ground state of interacting Dirac-fermion systems. In this system, the distance dependence of Casimir energy shows a complex oscillatory behavior by the interplay between the chemical potential, magnetic field, and inhomogeneous ground state. By decomposing the total Casimir energy into contributions of each Landau level, we elucidate what types of Casimir effects are realized from each Landau level: The lowest or some types of higher Landau levels lead to different behaviors of Casimir energies. Furthermore, we point out characteristic behaviors due to level splitting between different fermion flavors, i.e., up and down quarks. These findings provide new insights into Dirac-fermion (or quark) matter with a finite thickness.

Charged-current deep inelastic scattering plays a significant role in determining parton distribution functions with flavor separation. In this work, we present a systematic calculation of the charged-current semi-inclusive deep inelastic scattering (SIDIS) in the $eN$ collinear frame up to twist-3 level at leading order. Semi-inclusive refers to the process in which a jet is detected in addition to the scattered neutrino. We focus on neutrino-jet correlations in our calculation. We first present the differential cross section in terms of structure functions, followed by the differential cross section expressed in term of transverse momentum dependent parton distribution functions. We derive the complete set of azimuthal asymmetries and intrinsic asymmetries. We also introduce an observable $A^C$, defined as the ratio of the difference from the sum of differential cross sections for electron and positron semi-inclusive deep inelastic scattering. We notice that $A^C$ provides a sensitive probe for valence and sea quark distribution functions.

We derive and simplify the gravitational equations that apply in accelerating cosmological spacetimes. Solutions to these equations should be tantamount to all order resummations of the perturbative leading logarithms. We also discuss possible phenomenological applications to cosmological observables.

Recently, a quantum mechanical theory of quantum spaces described by a large $N$ non-commutative coordinates is proposed as a model for quantum gravity [arXiv:2406.01466]. In this paper, we construct Kerr black hole as a rotating noncommutative geometry solution of this theory. Due to rotation, the fuzzy sphere is deformed into a fuzzy ellipsoid, which matches exactly the outer horizon of the Kerr black hole in the Boyer-Lindquist coordinates. Together with a half-filled Fermi sea, the fuzzy solution reproduces the Bekenstein-Hawking entropy as well as the mass and angular momentum of the Kerr black hole. These results provide support that the proposed quantum mechanics of quantum spaces as a model of quantum gravity.

We investigate whether quantum gravity fluctuations can break chiral symmetry for fermions that are charged under a U(1) and an $\mathrm{SU}(N_{\mathrm{c}})$ gauge symmetry and thus closely resemble Standard-Model fermions. Unbroken chiral symmetry in the quantum-gravity regime is a necessary prerequisite to recover the Standard Model from a joint gravity-matter theory; if chiral symmetry is broken by quantum gravity, fermions cannot generically be much lighter than the Planck mass, and the theory is ruled out. To answer this, we work in a Fierz-complete basis of four-fermion interactions and explore whether they are driven to criticality. We discover that the interplay of quantum gravity with the non-Abelian gauge theory results in chiral symmetry breaking, because gravitational and gauge field fluctuations act together to produce bound states. Chiral symmetry breaking is triggered by four-fermion channels that first appear when non-Abelian charges are introduced and that become critical if the non-Abelian symmetry is gauged. Extrapolating our result to the Standard Model fermions, we conjecture that the non-Abelian gauge coupling, Abelian gauge coupling and Newton coupling are all bounded from above at trans-Planckian scales, if Standard Model fermions are to remain much lighter than the Planck mass. In contrast, fermions that are charged under a global non-Abelian group can remain light for arbitrarily large values of the Newton coupling. We find that different chiral symmetries are emergent at low energies, depending on the strength of the gravitational coupling. This is an example of fixed points with different degrees of enhanced global symmetry trading stability in fixed-point collisions driven by gravitational fluctuations.

We study the dynamics of the nonrelativistic spinning test body (STB) in the framework of Poincaré gauge theory of gravity (PGT), in which the weak equivalence principle is violated by the spin-gravitational interaction. We derive the general geodesic equation in terms of comoving tetrads. More concretely, we consider the case of the quadratic form of the Lagrangian, within the environment of a weak and static spherically symmetric space-time. We find that the trajectories of a STB deviate from the traditional Mathisson-Papapetrou equation, which is due to the coupling of the spin of the test particle to the torsion field of the environment. This allows us to test the theory with a free-fall experiment in the laboratory, such as with an atom interferometer. By using the previous data, we find the upper bound of the possible torsion field on Earth is given by up to $2.0\times {10}^1{\mathrm{m}}^{-1}$ and torsion gradient up to $3.1\times {10}^{-6}{\mathrm{m}}^{-2}$. This result may enable us to provide a theoretical foundation for future precision measurements of the existence of the fifth force.

We present a new mass generation mechanism for linearized gravity in three spacetime dimensions, which consists of a lower-dimensional Chern-Simons-like term added to the invariant action. The propagators of the gauge-fixed massive action show a massive pole and a good massless limit. Moreover, we show that, as the topological massive gravity model of Deser, Jackiw, and Templeton, this theory displays one propagating massive degree of freedom, which can be traced back to the transverse part of the spatial Ricci tensor. Finally, the action of this linearized massive gravity is characterized by an algebraic structure formed by a set of Ward operators, which uniquely determine the theory.

We introduce a covariant canonical quantization for a particle in curved spacetime that tracks operator-ordering ambiguities. Parametrizing spatial and temporal ordering, we derive a Hermitian Hamiltonian with leading quantum-relativistic corrections. In a uniformly accelerated frame, we show the semiclassical heat-capacity approximation misses these effects and then develop a perturbative quantum treatment using Airy-function modes to obtain analytical first- and second-order energy shifts. Including these shifts in the partition function yields nontrivial, ordering-dependent specific-heat corrections. Numerical studies for electrons in extreme electric fields and ultralight particles in strong gravitational fields demonstrate that these corrections become significant at intermediate temperatures. Enforcing the Tolman-Ehrenfest relation for spatial temperature variation further modulates the heat-capacity profile. Our results suggest that precision calorimetry in laser-acceleration or analog gravity setups could probe quantum-ordering effects in relativistic regimes.

We model a single black hole in equilibrium with a dark photon-cold dark matter environment. Representing the dark photon as a Proca field, we show that a Schwarzschild black hole grows vector-field “hair” when allowed to accrete from an infinite homogeneous bath of particles far from the horizon. We solve the Proca equation in linear perturbation theory, separating it using the vector spherical harmonics and Frolov-Krtouš-Kubizňák-Santos approaches for the odd-parity and even-parity sectors, respectively. In the “particle” dark matter regime, the field is purely infalling and exhibits a sharply peaked density profile, in concordance with the particle dark matter “spikes” studied in the literature. In the “wave” regime, the field exhibits standing waves, and the profile is smeared. We find a dark-matter density amplification upward of ${10}^7$ near the horizon. Though small for most black holes, we find the mass enclosed in the cloud can reach $\sim 1\%$ of the black hole mass for large supermassive black holes. These black holes are also most susceptible to vector dark matter accretion, with mass accretion rates as large as $10M_{\odot }/\mathrm{yr}$.

In [Phys. Rev. D 110, 103538 (2024)], we attempted to reconstruct the weak lensing convergence map $\widehat{\kappa }$ from cosmic magnification by linearly weighting the DECaLS galaxy overdensities in different magnitude bins of $grz$ photometry bands. The $\widehat{\kappa }$ map is correlated with cosmic shear at $20\sigma$ significance. However, the low galaxy number density in the DECaLS survey prohibits the measurement of $\widehat{\kappa }$ autocorrelation. In this paper, we apply the reconstruction method to the Dark Energy Survey year 3 (DES Y3) galaxies from the DES data release 2. With greater survey depth and higher galaxy number density, convergence-shear cross-correlation signals are detected with $S/N\approx 9$, 16, 20 at $0.4<z_{\kappa }<0.6$, $0.6<z_{\kappa }<0.8$, and $0.8<z_{\kappa }<1.0$, respectively. More remarkably, the $\widehat{\kappa }-\widehat{\kappa }$ correlations of the $0.4<z_{\kappa }<0.6$ and $0.6<z_{\kappa }<0.8$ bins show reasonably good agreement with predictions based on theoretical interpretation of $\widehat{\kappa }-\gamma$ measurement. This result takes a step further toward the cosmological application of our lensing reconstruction method.

Approximating neutrino oscillations as subgrid physics is an appealing prospect for simulators of core-collapse supernovae and neutron star mergers. Because flavor instabilities quickly lead to quasisteady states in oscillation calculations, it is widely believed that flavor mixing can be approximated in astrophysical simulations by mapping unstable states onto the appropriate asymptotic ones. Subgrid models of this kind, however, are not self-consistent. The miscidynamic theory of quantum-coherent gases furnishes a subgrid model that is.

Inverse decays are an interesting avenue for producing dark matter in the early Universe. We study in detail various phases of dark matter parameter space where inverse decays control its abundance, expanding on our work of inverse decay (INDY) dark matter and going beyond. The role of initial conditions and the impact of departure from kinetic equilibrium are investigated as well. We show how these inverse decay phases can arise in theories of a kinetically mixed dark photon and dark Higgs, with promising prospects for detection at upcoming experiments.

One of the most ambitious goals of quantum simulation of quantum field theory is the description of scattering in real time, which would allow not only for computation of scattering amplitudes, but also for studying the collision process step by step. The initial state of such simulation is made of typically two wave packets of stable particles moving on top of the vacuum, whose preparation is difficult. Here we extend a previous work to create wave packets of a general kind of particle from the vacuum in lattice gauge theories in various dimensions, including three-dimensional QCD for the first time. The conceptual foundation of this approach is the Haag-Ruelle scattering theory, and the only theoretical limitation is given by the presence of massless particles. In the context of digital quantum computation, the wave packet creation from the vacuum is implemented with the technique known as LCU (linear combination of unitaries). The preparation is performed successfully upon measuring an ancillary register with a certain probability, which vanishes polynomially in the lattice spacing, the wave-packet energy, and the momentum narrowness.

We present the results of our lattice QCD computation of the hadronic matrix elements relevant to the $h_c\to {\eta }_c\gamma$ and $h_b\to {\eta }_b\gamma$ decays by using the gauge configurations produced by the Extended Twisted Mass Collaboration with $N_f=2+1+1$ dynamical Wilson-Clover twisted mass fermions at five different lattice spacings with physical dynamical $u$, $d$, $s$ and $c$ quark masses (except for the coarsest lattice for which the lightest sea quark corresponds to a pion with $m_{\pi }\simeq 175\mathrm{MeV}$). While the hadronic matrix element for $h_c\to {\eta }_c\gamma$ is obtained directly, the one relevant to $h_b\to {\eta }_b\gamma$ is reached by working with heavy quark masses $m_H^{(n)}={\lambda }^{n-1}{m}_c$, with $\lambda \sim 1.24$ and $n=1,2,\dots ,6$, and then extrapolated to $m_b$ by several judicious Ansätze. In the continuum limit we obtain $\mathrm{\Gamma }(h_c\to {\eta }_c\gamma )=0.604(24)\mathrm{MeV}$, which is by a factor of 2.3 more accurate than the previous lattice estimates, and in good agreement with the experimental measurement. In the $b$-quark case we obtain $\mathrm{\Gamma }(h_b\to {\eta }_b\gamma )=46.0(4.8)\mathrm{keV}$.

A new method was proposed recently to investigate the location of the putative critical point of strongly interacting matter, governed by quantum chromodynamics. By approximating contours of constant entropy density at finite baryon chemical potential, the conditions for the existence of a critical point are solved. In this work, we analyze this method in the hadron resonance gas and Nambu–Jona-Lasinio models. We demonstrate that the prediction of the critical point in the HRG model is solely due to mesonic and baryonic degrees of freedom, and thus is not necessarily a signal of a critical point. We argue that such an expansion leads to a physically meaningful prediction only when applied near the critical point.