We investigate the diurnal modulation of the event rate for dark matter scattering on solid targets arising from the directionally dependent defect creation threshold energy. In particular, we quantify how this effect would help in separating dark matter signal from the neutrino background. We perform a benchmark analysis for a germanium detector and compute how the reach of the experiment is affected by including the timing information of the scattering events. We observe that for light dark matter just above the detection threshold the magnitude of the annual modulation is enhanced. In this mass range using either the annual or diurnal modulation information provides a similar gain in the reach of the experiment, while the additional reach from using both effects remains modest. Furthermore, we demonstrate that if the background contains a feature exhibiting an annual modulation similar to the one observed by DAMA experiment, the diurnal modulation provides for an additional handle to separate dark matter signal from the background.

An excess of 511 keV photons has been detected from the central region of the Milky Way. It has been suggested that the positrons responsible for this signal might be produced through the Hawking evaporation of primordial black holes. After evaluating the constraints from INTEGRAL, COMPTEL, and Voyager 1, we find that black holes in mass range of $\sim (1-4)\times {10}^{16}\mathrm{g}$ could potentially produce this signal if they make up a small fraction of the total dark matter density. Proposed MeV-scale gamma-ray telescopes such as AMEGO or e-ASTROGAM should be able to test this class of scenarios by measuring the diffuse gamma ray emission from the Milky Way’s inner halo.

We analytically investigate hydrodynamic attractor solutions in both Müller-Israel-Stewart (MIS) and kinetic theories in a viscous fluid system undergoing a Hubble expansion with a fixed expansion rate. We show that the gradient expansion for the MIS theory and the Chapman-Enskog expansion for the Boltzmann equation within the relaxation time approximation are factorially divergent. By resumming those asymptotic divergent series exactly via the Borel resummation technique (without using any approximations such as the Borel-Padé method), we obtain closed expressions for hydrodynamic attractor solutions. In both theories, we find that the hydrodynamic attractor solutions are globally attractive and only a single nonhydrodynamic mode exists. We also find that the hydrodynamic attractor solutions in the two theories disagree with each other when gradients become large, and that the speed of the attraction is different. Similarities and differences from hydrodynamic attractors in the Bjorken and Gubser flows are also discussed. Our results push the idea of far-from-equilibrium hydrodynamics in systems undergoing a Hubble expansion.

To solve the hierarchy problem, the relaxion must remain trapped in the correct minimum, even if the electroweak symmetry is restored after reheating. In this scenario, the relaxion starts rolling again until the backreaction potential, with its set of local minima, reappears. Depending on the time of barrier reappearance, Hubble friction alone may be insufficient to retrap the relaxion in a large portion of the parameter space. Thus, an additional source of friction is required, which might be provided by coupling to a dark photon. The dark photon experiences a tachyonic instability as the relaxion rolls, which slows down the relaxion by backreacting to its motion, and efficiently creates anisotropies in the dark photon energy-momentum tensor, sourcing gravitational waves. We calculate the spectrum of the resulting gravitational wave background from this new mechanism and evaluate its observability by current and future experiments. We further investigate the possibility that the coherently oscillating relaxion constitutes dark matter and present the corresponding constraints from gravitational waves.

We revisit Higgs inflation in the framework of a minimal extension of the Standard Model gauge symmetry by a $U(1{)}_{B-L}$ factor. Various aspects are taken into account, with particular focus on the role of the supersymmetry-breaking (SUSY) scale and the cosmological constraints associated with the gravitino. The scalar potential of the model is considered in the context of no-scale supergravity consisting of the $F$ part constructed from the Kähler function, the $D$ terms, and soft SUSY contributions. We investigate several limiting cases and by varying the SUSY scale from a few TeV up to intermediate energies, for a spectral index around $n_s\sim 0.9655$ and reheating temperature $T_r\le {10}^9\mathrm{GeV}$, we find that the value of the tensor-to-scalar ratio ranges from $r\approx {10}^{-3}$ to ${10}^{-2}$. Furthermore, it is shown that for certain regions of the parameter space the gravitino can live sufficiently long, and as such is a potential candidate for a dark matter component. In general, the inflationary scenario is naturally implemented and it is consistent with nonthermal leptogenesis, whereas the dominant decay channel of the inflaton yields right-handed neutrinos. Other aspects of cosmology and particle physics phenomenology are briefly discussed. Finally, we investigate the case where the inflaton is initially relaxed in a false minimum and estimate its probability to decay to the true vacuum.

Light neutralinos could be copiously produced from the decays of mesons generated in cosmic-ray air showers. These neutralinos can be long-lived particles in the context of $R$-parity violating (RPV) supersymmetric models, implying that they could be capable of reaching the surface of the earth and decay within the instrumental volume of large neutrino detectors. In this article, we use atmospheric neutrino data from the Super-Kamiokande experiment to derive novel constraints for the RPV couplings involved in the production of long-lived light neutralinos from the decays of charged $D$-mesons and kaons. Our results highlight the potential of neutrino detectors to search for long-lived particles, by demonstrating that it is possible to explore regions of parameter space that are not yet constrained by any fixed-target nor collider experiments.

The gamma factory is a proposal to back-scatter laser photons off a beam of partially-stripped ions at the LHC, producing a beam of $\sim 10\mathrm{MeV}$ to 1 GeV photons with intensities of ${10}^{16}$ to ${10}^{18}{\mathrm{s}}^{-1}$. This implies $\sim {10}^{23}$ to ${10}^{25}$ photons on target per year, many orders of magnitude greater than existing accelerator light sources and also far greater than all current and planned electron and proton fixed target experiments. We determine the gamma factory’s discovery potential through “dark Compton scattering,” $\gamma e\to eX$, where $X$ is a new, weakly-interacting particle. For dark photons and other new gauge bosons with masses in the 1 to 100 MeV range, the gamma factory has the potential to discover extremely weakly-interacting particles with just a few hours of data and will probe couplings as low as $\sim {10}^{-9}$ with a year of running. The gamma factory therefore may probe couplings lower than all other terrestrial experiments and is highly complementary to astrophysical probes. We outline the requirements of an experiment to realize this potential and determine the sensitivity reach for various experimental configurations.

Our first aim is to explore the effect of the collision integral with the insurance of instantaneous conservation of particle number on the charge and heat transport in a thermal QCD medium. The second aim is to see how the dimensional reduction due to strong magnetic field modulates the transport through the entangled effects such as the collision-time and occupation probability etc. in the collision integral. Final aim is to check how the quasiparticle description of partons, through the dispersion relation of thermal QCD in strong magnetic field, alters the aforesaid conclusions. We observe that the modified collision term expedites both transport, which is manifested by the larger magnitudes of electrical (${\sigma }_{\mathrm{el}}$) and thermal ($\kappa$) conductivities, in comparison to the relaxation collision term. As a corollary, the Lorenz number is dominated by the later and the Knudsen number is by the former. However, the strong magnetic field not only flips the dominance of collision term in the heat transport, it also causes drastic enhancement of both ${\sigma }_{\mathrm{el}}$ and $\kappa$ and reduction in the specific heat. As a result, the equilibration factor, the Knudsen number becomes much larger than one, which defies physical interpretation. Finally, the quasiparticle description of partons in the absence of strong magnetic field impedes the transport of charge and heat, resulting in tiny decrease of the conductivities. However, the strong magnetic field does noticeable observations: the conductivities now gets reduced to the physically plausible values, the temperature dependence of ${\sigma }_{\mathrm{el}}$ gets reversed, i.e., it now decreases with temperature, effect of collision integral gets smeared in $\kappa$ etc. The Knudsen number thus becomes much smaller than one, implying that the system be remained in equilibrium. These findings attribute to the fact that the collective oscillation in the dispersion relation of thermal QCD in strong magnetic field sets in much larger scale, manifested by the large in-medium flavor masses.

Understanding the origin and mechanism of the transverse polarization of hyperons produced in unpolarized proton-proton collision, $pp\to {\mathrm{\Lambda }}^{\uparrow }X$, has been one of the longstanding issues in high-energy spin physics. In the framework of the collinear factorization applicable to large-$p_T$ hadron productions, this phenomenon is a twist-3 observable which is caused by multiparton correlations either in the initial protons or in the process of fragmentation into the hyperon. We derive the twist-3 gluon fragmentation function (FF) contribution to this process in the leading order (LO) with respect to the QCD coupling constant. Combined with the known results for the contribution from the twist-3 distribution function and the twist-3 quark FF, this completes the LO twist-3 cross section. We also found that the model-independent relations among the twist-3 gluon FFs based on the QCD equation of motion and the Lorentz invariance property of the correlation functions guarantee the color gauge invariance and the frame independence of the cross section.

We report new measurements of the branching fraction $\mathcal{B}(D_s^{+}\to {\ell }^{+}\nu )$, where ${\ell }^{+}$ is either ${\mu }^{+}$ or ${\tau }^{+}(\to {\pi }^{+}{\overline{\nu }}_{\tau })$, based on $6.32{\mathrm{fb}}^{-1}$ of electron-positron annihilation data collected by the BESIII experiment at six center-of-mass energy points between 4.178 and 4.226 GeV. Simultaneously floating the $D_s^{+}\to {\mu }^{+}{\nu }_{\mu }$ and $D_s^{+}\to {\tau }^{+}{\nu }_{\tau }$ components yields $\mathcal{B}(D_s^{+}\to {\tau }^{+}{\nu }_{\tau })=(5.21\pm 0.25\pm 0.17)\times {10}^{-2}$, $\mathcal{B}(D_s^{+}\to {\mu }^{+}{\nu }_{\mu })=(5.35\pm 0.13\pm 0.16)\times {10}^{-3}$, and the ratio of decay widths $R=\frac{\mathrm{\Gamma }(D_s^{+}\to {\tau }^{+}{\nu }_{\tau })}{\mathrm{\Gamma }(D_s^{+}\to {\mu }^{+}{\nu }_{\mu })}=9.73_{-0.58}^{+0.61}\pm 0.36$, where the first uncertainties are statistical and the second systematic. No evidence of $CP$ asymmetry is observed in the decay rates $D_s^{\pm }\to {\mu }^{\pm }{\nu }_{\mu }$ and $D_s^{\pm }\to {\tau }^{\pm }{\nu }_{\tau }$: $A_{CP}({\mu }^{\pm }\nu )=(-1.2\pm 2.5\pm 1.0)\%$ and $A_{CP}({\tau }^{\pm }\nu )=(+2.9\pm 4.8\pm 1.0)\%$. Constraining our measurement to the Standard Model expectation of lepton universality ($R=9.75$), we find the more precise results $\mathcal{B}(D_s^{+}\to {\tau }^{+}{\nu }_{\tau })=(5.22\pm 0.10\pm 0.14)\times {10}^{-2}$ and $A_{CP}({\tau }^{\pm }{\nu }_{\tau })=(-0.1\pm 1.9\pm 1.0)\%$. Combining our results with inputs external to our analysis, we determine the $c\to \overline{s}$ quark mixing matrix element, $D_s^{+}$ decay constant, and ratio of the decay constants to be $|V_{cs}|=0.973\pm 0.009\pm 0.014$, $f_{D_s^{+}}=249.9\pm 2.4\pm 3.5\mathrm{MeV}$, and $f_{D_s^{+}}/f_{D^{+}}=1.232\pm 0.035$, respectively.

Axionlike particles (ALPs) are a compelling candidate for dark matter (DM), whose production is associated with the formation of a string-wall network. If walls bounded by strings persist, which requires the potential to have multiple local minima ($N>1$), they must annihilate before they become dominant. They annihilate mostly into gravitational waves and nonrelativistic ALPs. We show that for ALPs other than the QCD axion these gravitational waves, if produced at temperatures below 100 eV, could be detected by future cosmological probes for ALPs with mass from ${10}^{-16}$ to ${10}^6\mathrm{eV}$ that could constitute the entirety of the DM.

We develop a nonperturbative analysis of the electroproduction of heavy vector mesons ($\varphi$, $J/\mathrm{\Psi }$) from threshold to high energy. We use the holographic construction with bulk confinement enforced through a soft wall. Using Witten diagrams, we evaluate the pertinent cross sections for heavy vector mesons ($\varphi$, $J/\mathrm{\Psi }$) production and study their dependence on both the incoming virtual photon polarization as well as the outgoing polarization of the heavy meson. Our results for $J/\mathrm{\Psi }$ electroproduction compares well with the available HERA data at low and intermediate $Q^2$, and for a wide range of momentum transfer. We also predict the quasi-electroproduction of $J/\mathrm{\Psi }$ near threshold.

We derive constraints on scalar field theories coupled to gravity by using recently developed positivity bounds in the presence of gravity. It is found that a canonically normalized real scalar cannot have an arbitrarily flat potential unless some new physics enters well below the Planck scale. An upper bound on the scale of new physics is determined by loop corrections to the self-energy. Our result provides a swampland condition for scalar potentials.

The Palatini gravitational action is enlarged by an arbitrary function $f(\mathit{X})$ of the determinants of the Ricci tensor and the metric, $\mathit{X}=|\mathbf{det}.R|/|\mathbf{det}.g|$. The resulting Ricci-determinant theory exhibits novel deviations from general relativity. We study a particular realization where the extension is characterized by the square-root of the Ricci determinant, $f(\mathit{X})={\lambda }_{\mathrm{Edd}}\sqrt{\mathit{X}}$, which corresponds to the famous Eddington action. We analyze the obtained equations for perfect fluid source and show that the affine connection can be solved in terms of the energy density and pressure of the fluid through an obtained disformal metric. As an application, we derive the hydrostatic equilibrium equations for relativistic stars and inspect the significant effects induced by the square-root of the Ricci tensor. We find that an upper bound on ${\lambda }_{\text{Edd}}$, at which deviations from the predictions of general relativity on neutron stars become prominent, corresponds to the hierarchy between the Planck and the vacuum mass scales. The Ricci-determinant gravity that we propose here is expected to have interesting implications in other cosmological domains.

The existence of black holes is one of the key predictions of general relativity (GR) and therefore a basic consistency test for modified theories of gravity. In the case of spherical symmetry in GR the existence of an apparent horizon and its regularity is consistent with only two distinct classes of physical black holes. Here we derive constraints that any self-consistent modified theory of gravity must satisfy to be compatible with their existence. We analyze their properties and illustrate characteristic features using the Starobinsky model. Both of the GR solutions can be regarded as zeroth-order terms in perturbative solutions of this model. We also show how to construct nonperturbative solutions without a well-defined GR limit.

Exotic electromagnetic energy injection in the early Universe may alter cosmological recombination, and ultimately cosmic microwave background (CMB) anisotropies. Moreover, if energy injection is inhomogeneous, it may induce a spatially varying ionization fraction, and non-Gaussianity in the CMB. The observability of these signals, however, is contingent upon how far the injected particles propagate and deposit their energy into the primordial plasma, relative to the characteristic scale of energy injection fluctuations. In this study we inspect the spatial properties of energy deposition and perturbed recombination resulting from an inhomogeneous energy injection of sub-10 MeV photons, relevant to accreting primordial black holes (PBHs). We develop a novel Monte Carlo radiation transport code accounting for all relevant photon interactions in this energy range, and including secondary electron energy deposition efficiency through a new analytic approximation. For a specified injected photon spectrum, the code outputs an injection-to-deposition Green’s function depending on time and distance from the injection point. Combining this output with a linearized solution of the perturbed recombination problem, we derive time- and scale-dependent deposition-to-ionization Green’s functions. We apply this general framework to accreting PBHs, whose luminosity is strongly spatially modulated by supersonic relative velocities between cold dark matter and baryons. We find that the resulting spatial fluctuations of the free-electron fraction are of the same magnitude as its mean deviation from standard recombination, from which current CMB power spectra constraints are derived. This work suggests that the sensitivity to accreting PBHs might be substantially improved by propagating these inhomogeneities to CMB anisotropy power spectra and non-Gaussian statistics, which we study in subsequent papers.

We delineate the quark-hadron continuity by constructing QCD equations of state for neutron star dynamics, covering the wide range of charge chemical potential (${\mu }_Q$) and temperatures ($T$). Based on the nuclear-2SC continuity scenario, we match equations of state for nuclear and two-flavor color-superconducting (2SC) quark matter, where the matching baryon density is $n_B\simeq 1.5n_0$ ($n_0\simeq 0.16{\mathrm{fm}}^{-3}$: nuclear saturation density). The effective vector and diquark couplings in a quark matter model evolve as functions of $n_B$ or ($n_B,{\mu }_Q,T$), whose low density values are constrained by the nuclear matter properties and neutron star radii, with the high density behavior by the two solar mass ($2M_{\odot }$) constraint. With couplings dependent on $n_B$, we examined how smooth the nuclear-2SC continuity can be and found problems in matching nuclear and 2SC entropies at low temperatures; they differ unless the baryon Fermi velocity significantly increases to match with the quark’s, or the 2SC matter allows low energy collective modes whose velocities are as low as the baryon’s. This implies that the realization of the nuclear-2SC continuity, if possible, demands additional ingredients to the conventional nuclear and 2SC descriptions. To proceed with the continuity scenario, we enforce smooth matching by making the couplings ($n_B,{\mu }_Q,T$) dependent. In effect, this adds phenomenological contributions which we call “X” to emphasize our ignorance on the practical description. After the phenomenological matching, we take the rest as our predictions. The 2SC and color-flavor-locked (CFL) phases computed with these evolving couplings are called 2SCX and CFLX. The CFLX appears around $n_B\simeq 2–4n_0$ and, in contrast to the conventional CFL, has non-negligible dependence on $({\mu }_Q,T)$. To examine the astrophysical consequences of our modeling, we add charged leptons and neutrinos, and study the composition of matter for lepton fractions relevant for protoneutron stars and neutron star mergers. The abundance of neutrinos and thermal effects reduce the strangeness fraction and stiffen equations of state. For a neutrino trapped neutron star at $T\simeq 30\mathrm{MeV}$ with a lepton fraction $Y_L\simeq 0.05$, the mass is larger than its cold static counterpart by $\sim 0.1M_{\odot }$.

Neutron star tidal deformability extracted from gravitational wave data provides a novel probe to the interior neutron star structures and the associated nuclear equation of state (EOS). Instead of the popular composition of nucleons and leptons in neutron stars, we include hyperons and examine the role of hyperons in the tidal deformability and its impact on the symmetry energy in a relativistic mean-field approach with the density-dependent parametrizations. The hyperons are found to have a significant impact on the deformability, correlated sensitively with the onset density and fraction of hyperons in neutron star matter. A moderately lower onset density of hyperons can yield considerable modification to the tidal deformability and shift its inference on the nuclear EOS. The future measurements of the tidal deformability at multifiducial star masses are anticipated to lift the degeneracy between the contributions from the hyperon component and symmetry energy.

Searches for gravitational waves crucially depend on exact signal processing of noisy strain data from gravitational wave detectors, which are known to exhibit significant nonstationary and non-Gaussian behavior. In this paper, we study two distinct effects in the LIGO/Virgo data that reduce the sensitivity of searches: first, variations in the noise power spectral density (PSD) on timescales of more than a few seconds; and second, loud and abrupt transient “glitches” of terrestrial or instrumental origin. We derive a simple procedure to correct, at first order, the effect of the variation in the PSD on the search background. Given the knowledge of the existence of localized glitches, in particular segments of data, we also develop a method to insulate statistical inference from these glitches, so as to cleanly excise them without affecting the search background in neighboring seconds. We show the importance of applying these methods on the publicly available LIGO data and estimate an increase in the detection volume of at least 15% from the PSD-drift correction alone, due to the improved background distribution.