Exotic objects such as the Ellis wormhole are expected to act as gravitational lenses. Much like their nonexotic counterparts, information about these lenses can be found by considering the strong and weak lensing fields they induce. In this work, we consider how weak gravitational lensing flexion can provide information beyond that of shear. We find that directional flexion can distinguish between the case of a positive or negative convergence where directional shear cannot, and therefore can provide a unique lensing signature for objects with an Ellis wormhole-type metric. We also consider cosmic flexion, the flexion correlation function whose signal originates from the large-scale structure of the Universe, in the context of modified gravity. We find flexion to be a unique probe of parametric models of modified gravity, particularly in the case of scale-dependent phenomenological post-general relativity functions.

We study the finite distance boundary symmetry current algebra of the most general first order theory of 3D gravity. We show that the space of quadratic generators contains diffeomorphisms but also a notion of dual diffeomorphisms, which together form either a double Witt or centerless ${\mathrm{BMS}}_3$ algebra. The relationship with the usual asymptotic symmetry algebra relies on a duality between the null and angular directions, which is possible thanks to the existence of the dual diffeomorphisms.

In this work we apply a local quantum field theory (QFT) approach in order to analyze the connection between real-time observables and Euclidean thermal correlation functions. In particular, using data generated from the functional renormalization group (FRG) in the quark-meson model, we demonstrate that in-medium effects can be directly extracted from the spatial momentum dependence of the Euclidean propagators, in contrast to conventional approaches, which rely on the reconstruction from different Matsubara frequencies. As an application, we determine the analytic features that arise from the discrete spectral contribution to the pion correlation function, and calculate the nonperturbative shear viscosity arising from these states.

We consider a BRST-invariant generalization of the “massive background Landau gauge,” resembling the original Curci-Ferrari model that saw a revived interest due to its phenomenological success in modeling infrared Yang-Mills dynamics, including that of the phase transition. Unlike the Curci-Ferrari model, however, the mass parameter is no longer a phenomenological input, but it enters as a result of dimensional transmutation via a BRST-invariant dimension-2 gluon condensate. The associated renormalization constant is dealt with using Zimmermann’s reduction of constants program, which fixes the value of the mass parameter to values close to those obtained within the Curci-Ferrari approach. Using a self-consistent background field, we can include the Polyakov loop and probe the deconfinement transition, including its interplay with the condensate and its electric–magnetic asymmetry. We report a continuous phase transition at $T_c\approx 0.230\mathrm{GeV}$ in the SU(2) case and a first-order one at $T_c\approx 0.164\mathrm{GeV}$ in the SU(3) case, values which are again rather close to those obtained within the Curci-Ferrari model at one-loop order.

We discuss the definition of conserved quantities in asymptotically locally de Sitter spacetimes. One may define an analog of holographic charges at future and past infinity and at other Cauchy surfaces $I_t$ as integrals over the intersection of timelike surfaces $C$ and the Cauchy surface $I_t$. In general, the charges $Q^t$ defined on the Cauchy surface $I_t$ depend on $C$, but if gravitational flux is absent the charges are independent of $C$. On the other hand, if there is a net gravitational flux entering or leaving the spacetime region bounded by $C_1$, $C_2$ and two Cauchy surfaces then $\mathrm{\Delta }{Q}^t(C_1,C_2)=Q^t(C_1)-Q^t(C_2)$ changes by the same amount.

The $\nu \mathrm{GeN}$ experiment is aimed to investigate neutrino properties using antineutrinos from the reactor of the Kalinin Nuclear Power Plant. The experimental setup is located at about 11 meters from the center of the 3.1 ${\mathrm{GW}}_{\mathrm{th}}$ reactor core. Scattering of the antineutrinos from the reactor is detected with low energy threshold high purity germanium detector. Passive and active shieldings are used to suppress all kinds of backgrounds coming from surrounding materials and cosmic radiation. The description of the experimental setup together with the first results is presented. The data taken in regimes with reactor on (94.50 days) and reactor off (47.09 days) have been compared. No significant difference between spectra of two datasets is observed, i.e., no positive signals for coherent elastic neutrino-nucleus scattering are detected. Under Standard Model assumptions about coherent neutrino scattering an upper limit on a quenching parameter $\mathrm{k}<0.26$ (90% CL) in germanium has been set.

The coherent oscillation of ultralight dark matter in the mass regime around ${10}^{-23}\mathrm{eV}$ induces changes in gravitational potential with the frequency in the nanohertz range. This effect is known to produce a monochromatic signal in the pulsar timing residuals. Here we discuss a multifield scenario that produces a wide spectrum of frequencies, such that the ultralight particle oscillation can mimic the pulsar timing signal of stochastic common spectrum process. We discuss how ultralight dark matter with various spins produces such a wide band spectrum on pulsar timing residuals and perform the Bayesian analysis to constrain the parameters. It turns out that the stochastic background detected by NANOGrav can be associated with a wideband ultralight dark matter.

We evaluate the probability of (de)excitation and photon emission from a neutral, moving, nonrelativistic atom, coupled to the quantum electromagnetic field and in the presence of a thin, perfectly conducting plane (“mirror”). These results extend, to a more realistic model, the ones we had presented for a scalar model, where the would-be electron was described by a scalar variable, coupled to an (also scalar) vacuum field. The latter was subjected to either Dirichlet or Neumann conditions on a plane. In our evaluation of the spontaneous emission rate produced when the accelerated atom is initially in an excited state, we pay attention to its comparison with the somewhat opposite situation, namely, an atom at rest facing a moving mirror.

In this work we reconsider the solution describing black holes surrounded by a quintessencelike fluid. This geometry was introduced by Kiselev in 2003 and its physical source was originally modeled by an anisotropic fluid. We show that the Kiselev geometry is actually an exact solution of the Einstein equations coupled to nonlinear electrodynamics. More specifically, we show that the Kiselev geometry becomes an exact solution in the context of power-Maxwell electrodynamics, using either an electric ansatz or a magnetic one. In both cases the physical source can be modeled by a power-Maxwell Lagrangian, albeit with different powers corresponding to the electric or the magnetic charges. We briefly investigate the motion of charged particles in this geometry. Finally, we give the proper interpretation of the black-hole thermodynamics in this context. Similarly to the Schwarzschild-de Sitter case, we note the presence of the Schottky peaks in the heat capacity, signaling out the possibility of this thermodynamic black hole system to function as a continuous heat machine.

The approximate solution of the Klein-Gordon equation for a real scalar field of mass $\mu$ in the geometry of a Kerr black hole obtained by Detweiler [Detweiler, Phys. Rev. D 22, 2323 (1980)] is widely used in the analysis of the stability of black holes as well as the search of axionlike particles. In this work, we confirm a a missing factor $1/2$ in this solution, which was first identified in [Pani et al., Phys. Rev. D 86, 104017 (2012)]. The corrected result has strange features that put questions on the power-counting strategy. We solve this problem by adding the next-to-leading order (NLO) contribution. Compared to the numerical results, the NLO solution reduces the percentage error of the LO solution by a factor of 2 for all important values of $r_g\mu$. Especially the percentage error is $\lesssim 10\%$ in the region of $r_g\mu \lesssim 0.35$. The NLO solution also has a compact form and could be used straightforwardly.

We calculate the operator complexity for the displacement, squeeze and rotation operators of a quantum harmonic oscillator, assuming equal computational cost for the corresponding fundamental gates. The complexity of the time-dependent displacement operator is constant, equal to the magnitude of the coherent state parameter, while the complexity of unitary evolution by a generic quadratic Hamiltonian is proportional to the amount of squeezing and is sensitive to the time-dependent phase of the unitary operator. We apply these results to study the complexity of a free massive scalar field, finding that the complexity has a period of rapid linear growth followed by a saturation determined by the UV cutoff and the number of spatial dimensions. We also study the complexity of the unitary evolution of quantum cosmological perturbations in de Sitter space, which can be written as time-dependent squeezing and rotation operators on individual Fourier mode pairs. The complexity of a single mode pair at late times grows linearly with the number of $e$-folds, while the complexity at early times oscillates rapidly due to the sensitivity of operator complexity to the phase of unitary time evolution. Integrating over all modes, the total complexity of cosmological perturbations scales as the square root of the (exponentially) growing volume of de Sitter space, suggesting that inflation leads to an explosive growth in complexity of the Universe.

A dark energy with a negative energy density in the past can simultaneously address various cosmological tensions, and if it is to be positive today to drive the observed acceleration of the universe, we show that it should have a pole in its equation of state parameter. More precisely, in a spatially uniform universe, a perfect fluid (submitting to the usual continuity equation of local energy conservation) whose energy density $\rho (z)$ vanishes at an isolated zero $z=z_p$, necessarily has a pole in its equation of state parameter $w(z)$ at $z_p$, and, $w(z)$ diverges to positive infinity in the limit $z\to z_p^{+}$ and it diverges to negative infinity in the limit $z\to z_p^{-}$—we assume that $z_p$ is not an accumulation point for poles of $w(z)$. However, the converse statement that this kind of a pole of $w(z)$ corresponds to a vanishing energy density at that point is not true as we show by a counterexample. An immediate implication of this result is that one should be hesitant to observationally reconstruct the equation of state parameter of the dark energy directly, and rather infer it from a directly reconstructed dark energy density.

As one of the promising candidates of cold dark matter, primordial black holes (PBHs) were formed due to the collapse of overdense regions generated by the enhanced curvature perturbations during the radiation-dominated era. The enhanced curvature perturbations are expected to be non-Gaussian in some relevant inflation models, and hence, the higher-order loop corrections to the curvature power spectrum might be non-negligible as well as altering the abundance of PBHs. In this paper, we calculate the one-loop correction to the curvature power spectrum with local-type non-Gaussianities characterized by $F_{\mathrm{NL}}$ and $G_{\mathrm{NL}}$ standing for the quadratic and cubic non-Gaussian parameters, respectively. Requiring that the one-loop correction be subdominant, we find a perturbativity condition, namely, $|2cA{F}_{\mathrm{NL}}^2+6A{G}_{\mathrm{NL}}|\ll 1$, where $c$ is a constant coefficient which can be explicitly calculated in the given model, and $A$ denotes the variance of the Gaussian part of the enhanced curvature perturbation, and such a perturbativity condition can provide a stringent constraint on the relevant inflation models for the formation of PBHs.

Detectors with low thresholds for electron recoil open a new window to direct searches of sub-GeV dark matter (DM) candidates. In the past decade, many strong limits on DM-electron interactions have been set, but most on the one which is spin-independent (SI) of both dark matter and electron spins. In this work, we study DM-atom scattering through a spin-dependent (SD) interaction at leading order (LO), using well-benchmarked, state-of-the-art atomic many-body calculations. Exclusion limits on the SD DM-electron cross section are derived with data taken from experiments with xenon and germanium detectors at leading sensitivities. In the DM mass range of 0.1–10 GeV, the best limits set by the XENON1T experiment: ${\sigma }_e^{(\mathrm{SD})}<{10}^{-41}–{10}^{-40}{\mathrm{cm}}^2$, are comparable to the ones drawn on DM-neutron and DM-proton at slightly bigger DM masses. The detector’s responses to the LO SD and SI interactions are analyzed. In nonrelativistic limit, a constant ratio between them leads to an indistinguishability of the SD and SI recoil energy spectra. Relativistic calculations however show the scaling starts to break down at a few hundreds of eV, where the spin-orbit effects become sizable. We discuss the prospects of disentangling the SI and SD components in DM-electron interactions via spectral shape measurements, as well as having spin-sensitive experimental signatures without SI backgrounds.

We investigate a method of model-agnostic anomaly detection through studying jets, collimated sprays of particles produced in high-energy collisions. We train a transformer neural network to encode simulated QCD “event space” dijets into a low-dimensional “latent space” representation. We optimize the network using the self-supervised contrastive loss, which encourages the preservation of known physical symmetries of the dijets. We then train a binary classifier to discriminate a beyond the standard model resonant dijet signal from a QCD dijet background both in the event space and the latent space representations. We find the classifier performances on the event and latent spaces to be comparable. We finally perform an anomaly detection search using a weakly supervised bump hunt on the latent space dijets, finding again a comparable performance to a search run on the physical space dijets. This opens the door to using low-dimensional latent representations as a computationally efficient space for resonant anomaly detection in generic particle collision events.

The Standard Model effective field theory (SMEFT) is the tool of choice for studying deviations of Higgs couplings from the Standard Model predictions. The SMEFT is an expansion in an infinite tower of higher dimension operators, which is typically truncated at dimension-six. We consider the effective theory including dimension-eight operators and examine the matching to the 2 Higgs doublet model (2HDM) that is assumed to be valid at some high scale. Both the limits from the direct production of single Higgs bosons and the indirect limits on the Higgs trilinear coupling are considered in the context of the SMEFT matched to the 2HDM, and the importance of the assumptions about the expansions in powers of the high scale are examined numerically.

A new $U(1{)}_X$ gauge boson $X$ primarily interacting with a dark sector can have renormalizable kinetic mixing with the standard model (SM) $U(1{)}_Y$ gauge boson $Y$. This mixing besides introduces interactions of dark photon and dark sector with SM particles, it also modifies interactions among SM particles. The modified interactions can be casted into the oblique $S$, $T$, and $U$ parameters. We find that with the dark photon mass larger than the $Z$ boson mass, the kinetic mixing effects can reduce the tension of the $W$-mass excess problem reported recently by CDF from $7\sigma$ deviation to within $3\sigma$ compared with theory prediction. If there is non-Abelian kinetic mixing between $U(1{)}_X$ and $SU(2{)}_L$ gauge bosons, in simple renormalizable models of this type a triplet Higgs is required to generate the mixing. We find that this triplet with a vacuum expectation value of order 5 GeV can naturally explain the $W$-mass excess.

We investigate the possibility of keV scale thermal dark matter (DM) in a gauged $B-L$ extension of the standard model with three right-handed neutrinos (RHNs) and one vector like fermion in the context of cosmic inflation. The complex singlet scalar field responsible for the spontaneous breaking of $B-L$ gauge symmetry is nonminimally coupled to gravity and serves the role of inflaton. The keV scale vector like fermion DM gives rise to the possibility of warm dark matter, but it gets overproduced thermally. The subsequent entropy dilution due to one of the RHN decay can bring the thermal abundance of DM within the observed limit. The dynamics of both the DM and the diluter are regulated by the $B-L$ model parameters which are also restricted by the requirement of successful inflationary dynamics. We constrain the model parameter space from the requirement of producing sufficient entropy dilution to obtain correct DM relic, inflationary observables along with other phenomenological constraints. Interestingly, we obtain unique predictions for the order of lightest active neutrino mass ($m_{{\nu }_l}\lesssim {10}^{-14}\mathrm{eV}$) as a function of the $B-L$ gauge coupling for keV scale DM. The proposed framework also explains the origin of observed baryon asymmetry from the decay of other two heavier RHNs by overcoming the entropy dilution effect.

We calculate the spin-averaged generalized parton distributions (GPDs) of sea quarks in the proton at zero skewness from nonlocal covariant chiral effective theory, including one-loop contributions from intermediate states with pseudoscalar mesons and octet and decuplet baryons. A relativistic regulator is generated from the nonlocal Lagrangian where a gauge link is introduced to guarantee local gauge invariance, with additional diagrams from the expansion of the gauge link ensuring conservation of electric charge and strangeness. Flavor asymmetries for sea quarks at zero and finite momentum transfer, as well as strange form factors, are obtained from the calculated GPDs, and results compared with phenomenological extractions and lattice QCD.