Why matter and dark matter contents of the Universe are of the same order of magnitude, is one of the puzzles of modern cosmology. At the face of it, this would seem to point toward a basic similarity between matter and dark matter, suggesting perhaps the widely discussed mirror world picture as an ideal setting for a discussion of this issue. Here we outline a new and simple mirror world scenario to explain this puzzle. Our model uses the Affleck-Dine mechanism to generate baryon asymmetry and dark matter relic density leading to an asymmetric dark matter picture. We find that, for a certain parameter range of the model, the mirror electron is the unique possibility for dark matter whereas, in the complementary parameter range, the mirror baryons constitute the dark matter. In either case, the mirror photon must have mass in the MeV range for consistency with observations. For the case of mirror electron dark matter, the model predicts a lower bound on the amount of dark radiation, i.e., $\mathrm{\Delta }{N}_{\mathrm{eff}}\ge 0.007$.

We develop a new approach to Vlasov Perturbation Theory (VPT) that solves for the hierarchy of cumulants of the phase-space distribution function to arbitrarily high truncation order in the context of cosmological structure formation driven by collisionless dark matter. We investigate the impact of higher cumulants on density and velocity power spectra as well as the bispectrum, and compare to scale-free $N$-body simulations. While there is a strong difference between truncation at the first cumulant, i.e., standard perturbation theory (SPT), and truncation at the second (i.e., including the velocity dispersion tensor), the third cumulant has a small quantitative impact and fourth and higher cumulants only have a minor effect on these summary statistics at weakly non-linear scales. We show that spurious exponential growth is absent in vector and tensor modes if scalar-mode constraints on the non-Gaussianity of the background distribution function that results from shell crossing are satisfied, guaranteeing the screening of UV modes for all fluctuations of any type, as expected physically. We also show analytically that loop corrections to the power spectrum are finite within VPT for any initial power spectra consistent with hierarchical clustering, unlike SPT. Finally, we discuss the relation to and contrast our predictions with effective field theory (EFT), and discuss how the advantages of VPT and EFT approaches could be combined.

We examine the detectability of $\gamma$-ray emission originating from the radioactive decays of unstable nuclei that are synthesized in relativistic outflows launched in magnetorotational core-collapse supernovae. The observed lines have enhanced energies due to the Lorentz boosted nuclei and can also be seen until later times due to time dilation of the rest-frame half-lives. We find that instruments like e-ASTROGAM and INTEGRAL/SPI are sensitive to these boosted line emissions from hundreds of keV to tens of MeV at a distance of 10 kpc over timescales of tens of days. For favorable viewing angles, these decays can be detected to extragalactic distances for rapidly spinning protomagnetar models. On the other hand, detection for off-axis jets is challenging, even for a supernova at the Galactic Center. Measuring multiple decay lines in addition to the integrated luminosity over $\sim 10\mathrm{days}$ postbounce would allow for the ability to distinguish between models and shed light on central engine properties like magnetic field and spin.

Gravitational lensing galaxies are commonly modeled with elliptical density profiles, to which angular complexity is sometimes added through a multipole expansion—encoding deformations of the elliptical isodensity contours. The formalism that is widely used in current studies and software packages, however, employs perturbations that are defined with respect to a circle. In this work, we show that this popular formulation (the “circular multipoles”) leads to perturbation patterns that depend on the axis ratio and do not agree with physical expectations (from studies of galaxy isophotal shapes) when applied to profiles that are not near circular. We propose a more appropriate formulation, the “elliptical multipoles,” representing deviations from ellipticity suited for any axis ratio. We solve for the lensing potentials associated with the elliptical multipoles of any order $m$, assuming that the reference profile is near isothermal. We implement these solutions into the lens modeling package lenstronomy, and assess the importance of the multipole formulation by comparing flux-ratio perturbations in mock lensed systems with quadruply imaged quasars: we show that elliptical multipoles typically produce smaller flux-ratio perturbations than their circular counterparts.

Dark matter admixed neutron stars provide a promising avenue for observationally probing the dark matter characteristic. In this study, we examine nonradial oscillations in neutron stars containing self-interacting dark matter, which interacts with normal matter exclusively via gravity. To achieve this, we derive a new set of perturbation equations for a multifluid system under the Cowling approximation. Using these equations, we analyze the oscillation spectra and identify additional modes associated with dark matter, alongside those of normal matter. We find that the frequency behavior becomes more intricate with increasing self-coupling strength of dark matter, particularly as the stellar structure transitions between dark core and dark halo configurations, depending on the total stellar mass. Nevertheless, we find that in the dark core structure, the fundamental ($f$) mode frequencies associated with dark matter exceed those of normal matter, at least when the central energy densities of both fluids are equal. Furthermore, we find that the $f$-mode frequencies associated with normal matter in dark core configurations adhere to a universal relation between the mass-scaled frequency and stellar compactness.

Spaceborne gravitational-wave observatories utilize a postprocessing technique known as time-delay interferometry (TDI) to reduce the otherwise overwhelming laser frequency noise by around 8 orders of magnitude. While, in its traditional form, TDI considers the spacecraft as point masses, recent studies have enhanced this simplified scenario by incorporating more realistic metrology chain models, which include onboard optical, electronic, and digital delays. These studies have updated the TDI algorithm to include onboard delays obtained from prelaunch and in-flight calibrations. Conversely, the processing scheme presented in this article treats onboard delays as an integral part of the TDI combinations: instead of having separate calibration stages, it directly expresses all delays appearing in the algorithm in terms of onboard measurements, especially pseudo-random-noise ranging (PRNR) measurements. The only onboard delays that need to be corrected in our processing scheme are PRNR delays in the digital domain, which are determined by commandable digital-signal-processing parameters; hence, they can be easily managed in postprocessing. Furthermore, our processing scheme does not require a prior interspacecraft clock synchronization, and it automatically corrects for potential relative drifts between the clocks driving local phase measurement systems. The proposed observable-based formulation closely relates TDI to the actual metrology system, and it clearly outlines how to manage onboard measurements in postprocessing. Hence, it is expected to lead to fundamental advancements in TDI, providing both conceptual completeness and unique practical benefits.

Through model-to-data comparisons from heavy-ion collisions, it has been shown that the quark gluon plasma has an extremely small shear viscosity at vanishing densities. At large baryon densities, significantly less is known about the nature of the shear viscosity from quantum chromodynamics (QCD). Within heavy-ion collisions, there are three conserved charges: baryon number (B), strangeness (S), and electric charge (Q). Here we calculate the shear viscosity in two limits using perturbative QCD (pQCD) and an excluded-volume hadron resonance gas at finite BSQ densities. We then develop a framework that interpolates between these two limits such that shear viscosity is possible to calculate across a wide range of finite BSQ densities. We find that the pQCD and hadron resonance gas calculations have different BSQ density dependencies such that a rather nontrivial shear viscosity appears at finite densities.

The supersymmetric custodial triplet model (SCTM), which is a fully supersymmetric generalization of the Georgi-Machacek (GM) model, is constructed by extending the Higgs sector of the minimal supersymmetric standard model by three triplet chiral superfields with hypercharge $Y=0,\pm 1$, in order to maintain the holomorphy of the superpotential and satisfy the requirements of anomaly cancellation. The global $SU(2{)}_L\otimes SU(2{)}_R$ symmetry has to be respected for the superpotential and soft supersymmetry breaking sector, where the former will only be broken by the Yukawa couplings and the latter one will be broken spontaneously to the custodial $SU(2{)}_V$ symmetry after electroweak symmetry breaking similar to the GM model. The ensuing complicated spectrum not only gives rich collider phenomenology but also provides more available weakly interacting massive particle (WIMP) dark matter (DM) candidates. In this paper, we explore the viability of WIMP solutions for DM in the SCTM, by considering the increasingly stringent constraints from direct detection DM experiments. Our numerical simulations show that a significant portion of the SCTM parameter space remains viable despite these constraints and will be fully tested in future experiments.

We present a lattice QCD investigation of isoscalar tetraquark systems involving bottom quarks with explicit flavor content $bb\overline{u}\overline{d}$ and $bs\overline{u}\overline{d}$. In the doubly bottom sector, the study focuses on axial-vector $J^P=1^{+}$ quantum numbers, whereas in the $bs\overline{u}\overline{d}$ channel, both axial-vector $J^P=1^{+}$ and scalar $J^P=0^{+}$ quantum numbers are investigated in search of signatures for possible tetraquark bound states. The calculations are performed on four ensembles with dynamical quark fields up to the charm quark generated by the MILC Collaboration, with lattice spacings ranging from approximately 0.058 to 0.12 fm, and at different values of the valence light quark mass $m_{u/d}$, corresponding to pseudoscalar meson masses, $M_{ps}=0.5$, 0.6, and 0.7 GeV. The energy eigenvalues in the finite volume are determined by applying a variational procedure to correlation matrices constructed from two-meson interpolating operators and diquark-antidiquark operators. Continuum extrapolated elastic $S$-wave scattering amplitudes of $B{B}^{*}$, $K{B}^{*}$, and $KB$ are extracted from the ground-state eigenenergies following a finite-volume analysis à la Lüscher. The chiral and continuum extrapolated binding energy estimates for the isoscalar axial-vector doubly bottom tetraquark $T_{bb}$ from the extracted elastic $B{B}^{*}$ $S$-wave scattering amplitudes is found to be $\mathrm{\Delta }{E}_{T_{bb}}(1^{+})=-116{(}_{-36}^{+30})\mathrm{MeV}$. In the $bs\overline{u}\overline{d}$ system, no statistically significant deviations were observed in the ground-state energies from the respective elastic threshold energies, leading to no conclusive evidence for any bound states.

The quark mass dependence of octet baryon magnetic polarizabilities is examined at the level of individual quark-sector contributions in the uniform background-field approach of lattice QCD. The aim is to understand the direct impact of increasing the mass of a quark flavor on the magnetic polarizability and indirect or environmental effects associated with changing the mass of spectator quarks, insensitive to the background magnetic field. Noting the need to set the electric charge of some quark flavors to zero, a fractionally charged baryon formalism is introduced. We find that increasing the mass of the charged quark flavor directly causes its contribution to the magnetic polarizability to decrease. However, increasing the mass of the spectator quark flavor indirectly acts to increase the magnetic polarizability. To gain a deeper understanding of these effects, we evaluate the predictions of the constituent quark model in this context. While the model provides a compelling explanation for the environmental effect of varying the spectator quark mass, an explanation of the direct mass dependence is more complicated as competing factors combine in the final result. The lattice results indicate the key factor is a reduction in the constituent quark magnetic moment with increasing quark mass, as it governs the strength of the magnetic transition to the nearby decuplet baryon.

We argue that the Standard Model is accompanied by a new pseudoscalar degree of freedom, ${\eta }_w$ meson, which cancels the topological susceptibility of the electroweak vacuum and gets its mass from this effect. The prediction is based on the analyticity properties of the Chern-Simons correlator combined with the basic features of gravity. Depending on the quality level of the $U(1{)}_{B+L}$ symmetry, the ${\eta }_w$ emerges as a $B+L$ pseudo-Goldstone boson or as a Stückelberg 2-form of the electroweak gauge redundancy. An intriguing scenario of the first category is the emergence of ${\eta }_w$ in the form of the phase of a $U(1{)}_{B+L}$-violating fermion condensate triggered by the instantons, somewhat similar to the ${\eta }^{\prime }$ meson in QCD. Regardless of its origin, the presence of the ${\eta }_w$ meson in the theory appears to be a matter of consistency.

True muonium (${\mu }^{+}{\mu }^{-}$) is one of the cleanest bound states, being composed only of leptons, along with true tauonium and positronium. Unlike the latter, true muonium and true tauonium have not been observed so far. This article shows that the spin-0 state of true muonium (para-TM), decaying into two photons, can be observed at a discovery level of significance in the dataset already collected by the Belle-II experiment at the $\mathrm{\Upsilon }(4S)$ peak, with certain assumptions on systematic uncertainties. Para-TM is produced via photon-photon fusion, and its observation is based on the detection of the photon pair resulting from its decay, on top of the continuum background due predominantly to light-by-light scattering. Trigger, acceptance and isolation cuts, along with calorimeter resolution and reconstruction efficiency, are taken into account during the Monte Carlo simulation of both signal and background. In order to separate signal and background, a machine learning method, based on extremely randomized trees, is trained on simulated events. Finally, the expected statistical significance of TM observation is evaluated, taking into account systematic uncertainties in a parametric fashion.

We introduce a novel, well-defined four-dimensional regularized Gauss-Bonnet theory of gravity by applying a dimensional regularization procedure. The resulting theory is a vector-tensor theory within the generalized Proca class. We then consider the static spherically symmetric solutions of this theory and find black hole solutions that acquire primary hair. Notably, one of the integration constants associated with the Proca field is not manifest in the original metric, but under a disformal transformation of the seed solution, it emerges as a second, independent primary hair. This additional hair acts as an effective cosmological constant in the disformed geometry, even in the absence of a bare cosmological constant term. We further generalize these black hole solutions to include electromagnetic charges and effects related to the scalar-tensor counterparts of the regularized Gauss-Bonnet theory. We discuss the implications of our findings to observations.

Starting from the isomorphism between the anti–de Sitter (AdS) Carroll and Poincaré algebras, we obtain the magnetic AdS Carroll gravity in three dimensions. Moreover, we derive the first set of asymptotic conditions for the AdS Carroll structure, and we prove that the asymptotic symmetry algebra is given by the ${\mathfrak{bms}}_3$ algebra. By mapping the three-dimensional asymptotically flat solutions of Poincaré gravity into an AdS Carroll spacetime, we demonstrate that the resulting solutions satisfy the field equations of the Chern-Simons formulation of AdS Carroll gravity, and we note that this solution possesses an infinite set of Killing vectors.

In this paper, we introduced the unified three-form dark sector (UTFDS) model, a unified dark sector model that combines dark energy and dark matter through a three-form field. In this framework, the potential of the three-form field acts as dark matter, while the kinetic term represents dark energy. The interaction between dark matter and dark energy is driven by the energy exchange between these two terms. Given the dynamical equations of UTFDS, we provide an autonomous system of evolution equations for UTFDS and perform a stability analysis of its fixed points. The result aligns with our expectations for a unified dark sector. Furthermore, we discover that the dual Lagrangian of the UTFDS Lagrangian is equivalent to a Dirac-Born-Infeld Lagrangian. By fixing the parameter $\kappa X_0$ to 250, 500, and 750, we refer to the resulting models as the ${\mathrm{UTFDS}}_{250}$, ${\mathrm{UTFDS}}_{500}$, and ${\mathrm{UTFDS}}_{750}$ model, respectively. We then place constraints on these three models and the $\mathrm{\Lambda }$ cold dark matter ($\mathrm{\Lambda }\mathrm{CDM}$) model in light of the Planck 2018 cosmic microwave background (CMB) anisotropies, redshift space distortions (RSDs) observations, baryon acoustic oscillation (BAO) measurements, and the $S_8$ prior chosen according to the KiDS1000 weak gravitational lensing (WL) measurement. We find that the ${\mathrm{UTFDS}}_{500}$ is the only one among the four models where both ${\sigma }_8$ and $S_8$ tensions, between CMB and $\mathrm{RSD}+\mathrm{BAO}+\mathrm{WL}$ datasets, are below $2.0\sigma$. Furthermore, the tensions are relieved without exacerbating the $H_0$ tension. Although both the CMB and $\mathrm{RSD}+\mathrm{BAO}+\mathrm{WL}$ datasets provide definite/positive evidence favoring $\mathrm{\Lambda }\mathrm{CDM}$ over the ${\mathrm{UTFDS}}_{500}$, the evidence is not strong enough to rule out further study of this model.

The early dark energy (EDE) extension to $\mathrm{\Lambda }$ cold dark matter ($\mathrm{\Lambda }\mathrm{CDM}$) has been proposed as a candidate scenario to resolve the “Hubble tension.” We present new constraints on the EDE model by incorporating new data from the Dark Energy Spectroscopic Instrument (DESI) baryon acoustic oscillation (BAO) survey and cosmic microwave background (CMB) lensing measurements from the Atacama Cosmology Telescope (ACT) sixth data release and Planck NPIPE data. We do not find evidence for EDE. The maximum fractional contribution of EDE to the total energy density is $f_{\mathrm{EDE}}<0.091$ [95% confidence level (CL)] from our baseline combination of Planck CMB, CMB lensing, and DESI BAO. Our strongest constraints on EDE come from the combination of Planck CMB and CMB lensing alone, yielding $f_{\mathrm{EDE}}<0.070(95\%\mathrm{CL})$. We also explore extensions of $\mathrm{\Lambda }\mathrm{CDM}$ beyond the EDE parameters by treating the total neutrino mass as a free parameter, finding $\sum m_{\nu }<0.096\mathrm{eV}(95\%\mathrm{CL})$ and $f_{\mathrm{EDE}}<0.087(95\%\mathrm{CL})$. For the first time in EDE analyses, we perform Bayesian parameter estimation using neural network emulators of cosmological observables, which are on the order of 100 times faster than full Boltzmann solutions.

The Hubble constant, $H_0$, which is a crucial parameter in astrophysics and cosmology, is under significant tension. We explore an independent technique to measure $H_0$ based on the time delay cosmography with strong gravitational lensing of a supernova lensed by a galaxy cluster, focusing on SN Refsdal in MACS $\mathrm{J}1149.5+2223$, the first gravitationally lensed supernova with resolved multiple images. We carefully examine the dependence of constraints on the Hubble constant on the choice of lens mass models, employing 23 lens mass models with different assumptions on dark matter halos and external perturbations. Remarkably, we observe that the dependence on the choice of lens mass models is not significantly large, suggesting the robustness of the constraint on the Hubble constant from SN Refsdal. We combine measurements for the 23 lens mass models to obtain $H_0={70.0}_{-4.9}^{+4.7}\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$ assuming equal weighting. We find that best-fitting Hubble constant values correlate with radial density profiles of the lensing cluster, implying room for improving the constraint on the Hubble constant with future observations of more multiple images. We also find a clear correlation between best-fitting Hubble constant values and magnification factors of supernova multiple images. This correlation highlights the importance of gravitationally lensed Type Ia supernovae for accurate and robust Hubble constant measurements.

Recent observational data seem to show $\gtrsim 3\sigma$ evidence for an evolving dark energy (DE) against the cosmological constant, so the standard $\mathrm{\Lambda }$ Cold Dark Matter ($\mathrm{\Lambda }\mathrm{CDM}$) model. In this paper, we perform the search for the primordial gravitational waves with the potential prerecombination solutions to the Hubble tension, using recent DESI baryon acoustic oscillation measurements combined with BICEP/Keck cosmic microwave background (CMB) B-mode polarization, Planck CMB, and Pantheon supernova data, which reveal that the low bound of the tensor-to-scalar ratio $r$ is $>1.5\sigma$ nonzero with the best fit $r_{0.05}\sim 0.01$ and the scalar spectral index $n_s=1$ (both $|r_{0.05}-0.01|$ and $|n_s-1|\sim \mathcal{O}(0.001)$). In particular, we observe the unnoticed impact of CMB B-mode polarization data for constraining the nature of DE, which together with early dark energy solutions to the Hubble tension is calling for the return of postrecombination $\mathrm{\Lambda }\mathrm{CDM}$.

At least two mechanisms effectively transfer interplanetary magnetic field (IMF) disturbances into the atmosphere. First, the inflow of solar wind into the ionosphere at low latitudes significantly enhances the total vertical electron content, increasing atmospheric conductivity. Second, Forbush decreases (FD) reduce the cosmic ray flux by a few percent, lowering ionization levels at middle latitudes and decreasing conductivity. Changes in atmospheric conductivity affect the global electric circuit and atmospheric electric field (AEF). However, to study the response of AEF to geomagnetic storms (GMS), it is necessary to carefully monitor atmospheric conditions before and during storms, as meteorological influences can be much stronger than those of GMS. Charged clouds above detectors, lightning flashes, and abrupt weather changes significantly impact near-surface electric field (NSEF) variations, which serve as a proxy for AEF measured at the Earth’s surface. The facilities at Aragats station monitor all environmental parameters on a one-minute timescale. We analyze four GMS events described in previous studies, detailing the corresponding weather conditions to isolate the genuine influence of GMS on NSEF. The GMS of June 22, 2015, and September 8, 2017, occurred under fair-weather conditions, providing clear evidence of GMS influence on NSEF. These events were long-lasting, positive, and modest, ranging from 0.2 to $0.3\mathrm{kV}/\mathrm{m}$, and coincided with the depletion phase of FD. The sky was clear, no rain was detected, and lightning flashes from previous thunderstorms were more than 20 km from the station. The other two events did not meet favorable weather criteria, and their occurrence during GMS seemed incidental. We identify a feature that may indicate the solar (FD) origin of NSEF enhancement: a dip in the enhanced NSEF during the daytime.