We take a bottom-up approach to find the interaction potential between the anti–de Sitter (AdS) black hole molecules under mean-field approximation. We start with the equation of state of dyonic AdS black holes in a fixed charge ensemble and use the method of classical cluster expansion to find the mean-field potential. We show that the Lennard-Jones (LJ) potential is a feasible choice to describe the equation of state. The LJ potential describes a two-body interaction. There exists a critical distance $r_0$ such that two interacting particles repel (attract) each other for $r<r_0$ ($r>r_0$). We compute the value of $r_0$ for dyonic AdS black holes and compare the result obtained from the Ruppeiner scalar curvature. Our analysis shows how the electric (and magnetic) charge affects the interaction between black hole molecules.

We study the prelude to black-hole formation using a suspended shell composed of physical matter that fulfills the dominant energy condition. Here, the collapse of the shell is brought to rest when the formation of the horizon is imminent but has not yet occurred. As the main achievement of this work, we obtain the Feynman propagator which connects the interior and the exterior of the shell within two local coordinate patches. It is derived by drawing an analogy to the propagation of light across interfaces that separate regions with different susceptibilities inside a medium. As a first application, we use this propagator to determine the vacuum persistence amplitude in the presence of external sources. On timescales much shorter than the Page time, we find that the amplitude builds up with time yet remains consistent with perturbative unitarity.

We define and sketch the generalized ergosphere of the Majumdar-Papapetrou (MP) spacetime. In particular, we demonstrate the existence of closed orbits of negative energy that live outside the event horizon of such a spacetime. Relying on the Penrose process mechanism, we use these orbits to illustrate the possibility of energy extraction from a MP binary black hole by particle scattering. We also analyze the efficiency of the process and construct explicit examples that optimize the extraction of energy. Lastly, we show how such concepts can be extended to a pair of noncoalescing Kerr black holes described by the Cabrera-Munguia, Manko and Ruiz (CMMR) metric.

Hawking radiation of astrophysical black holes is minute and thought to be unobservable. However, different mechanisms could contribute to an anomalously high emission rate: extra dimensions, new “dark” families of bosons or fermions, or a lower fundamental Planck scale. Do black holes flood the Universe with gravitational waves via mass loss? Here, we show that the formation of black hole binaries and the absence of a stochastic background of gravitational waves can limit the emission rate to $|\dot{M}|\lesssim {10}^{-15}{M}_{\odot }/\mathrm{yr}$ ($|\dot{M}|\lesssim {10}^{-13}{M}_{\odot }/\mathrm{yr}$), when the mass loss branching ratio to gravitons is unity (${10}^{-2}$). This constraint is up to seven orders of magnitude more stringent than bounds from resolvable inspiralling binaries.

We study the evolution of cosmological domain walls in models with asymmetric potentials. Our research goes beyond the standard case of spontaneous breaking of an approximate symmetry. When the symmetry is explicitly broken the potential exhibits nearly degenerate minima which can lead to creation of a metastable network of domain walls. The time after which the network will decay depends on the difference of values of the potential in minima, its asymmetry around the maximum separating minima, and the bias of the initial distribution of the field. The effect of asymmetry around the maximum separating minima is a novel one that we study with a new type of potential. Using numerical lattice simulations we determine relative importance of these factors on decay time of networks for generic potentials. We find that even very small departures from the symmetric initial distribution case leads to rapid decay of the domain wall network. As a result creation of a long lasting network capable of producing observable gravitational wave signals is much more difficult than previously thought. On the other hand details of the shape of the potential turn out to be much less important than expected and the evolution of network from symmetric distribution is controlled by the difference of values of the potential in the minima.

We present 500 high-resolution, full-sky millimeter-wave deep learning (DL) simulations that include lensed CMB maps and correlated foreground components. We find that these MillimeterDL simulations can reproduce a wide range of non-Gaussian summary statistics matching the input training simulations, while only being optimized to match the power spectra. The procedure we develop in this work enables the capability to mass produce independent full-sky realizations from a single expensive full-sky simulation, when ordinarily the latter would not provide enough training data. We also circumvent a common limitation of high-resolution DL simulations that they be confined to small sky areas, often due to memory or GPU issues; we do this by developing a “stitching” procedure that can recover the large-scale, high-order statistics and avoid discontinuities or repeated features in the maps. In addition, since our network takes as input a full-sky lensing convergence map, it can in principle take a full-sky lensing convergence map from any large-scale structure (LSS) simulation and generate the corresponding lensed CMB and correlated foreground components at millimeter wavelengths; this is especially useful in the current era of combining results from both CMB and LSS surveys, which require a common set of simulations.

A new detection method using magnetization generated at triggered radiative emission of neutrino pairs, $|e⟩\to |g⟩+\gamma +{\sum }_{ij}{\nu }_i{\overline{\nu }}_j$ (which is the atomic deexcitation from state $|e⟩$ to state $|g⟩$ while emitting the sum of neutrino pairs ${\sum }_{ij}{\nu }_i{\overline{\nu }}_j$ accompanied by a photon $\gamma$), is investigated in order to determine unknown neutrino properties: the absolute neutrino masses of ${\nu }_i$ and Majorana/Dirac distinction. Magnetization associated with radiative emission of neutrino pair events has a parity violating component intrinsic to weak interaction enforced by the crystal field effect in solids, and greatly helps background rejection of QED origin even when these backgrounds are amplified. In proposed experiments we prepare a coherently excited body of trivalent lanthanoid ions, ${\mathrm{Er}}^{3+}$ (a best candidate ion so far found), doped in a transparent dielectric crystal. The magnetic moment $\mu ⟨\overrightarrow{S}·\overrightarrow{k}⟩/k$ arising from generated electron spin $\overrightarrow{S}$ parallel to trigger photon direction $\overrightarrow{k}/k$ is parity odd, and is absent in QED processes. The generated magnetic field of order nano-Gauss is stored in crystals long after pair emission event till spin relaxation time. An improved calculation method of coherent rate and angular distribution of magnetization is developed in order to incorporate finite size effect of crystal target beyond the infinite size limit in previous calculations.

We present the results of the first calculation of the logarithmic corrections to the QCD contribution to same-sign $W$-pair production, $pp\to e^{\pm }{\nu }_e{\mu }^{\pm }{\nu }_{\mu }jj$, for same-sign charged leptons. This includes all leading logarithmic contributions which scale as ${\alpha }_W^4{\alpha }_s^{2+k}{\log }^k(\widehat{s}/p_{\perp }^2)$. This process is important for the study of electroweak couplings and hence the QCD contributions are usually suppressed through a choice of vector boson scattering cuts. These select regions of phase space where logarithms in $\widehat{s}/p_{\perp }^2$ are enhanced. While the logarithmic corrections lead to a small change for the cross sections, several distributions relevant for experimental studies are affected more significantly.

Higher-derivative corrections to cosmological effective actions in string theory are largely constrained by T-duality, but have been computed hitherto only to the first few orders in the string scale ${\alpha }^{\prime }$. The functional renormalization group, in conjunction with the strong constraints imposed by T-duality, allows us to derive cosmological effective actions to all orders in ${\alpha }^{\prime }$ while avoiding “truncations” of the theory space. We show that the resulting higher-derivative ${\alpha }^{\prime }$-corrections forbid the existence of de Sitter vacua, at least in regimes where string-loop corrections can be neglected. Our findings thus support the no-de Sitter swampland conjecture in the presence of all-order effects in ${\alpha }^{\prime }$.

The elastic scattering of two real photons in vacuum is one of the most elusive of the fundamentally new processes predicted by quantum electrodynamics. This explains why, although it was first predicted more than eighty years ago, it has so far remained undetected. Here we show that in present-day facilities, the elastic scattering of two real photons can become detectable far off axis in an asymmetric photon-photon collider setup. This may be obtained within one day of operation time by colliding 1 mJ extreme ultraviolet pulses with the broadband gamma-ray radiation generated in nonlinear Compton scattering of ultrarelativistic electron beams with terawatt-class optical laser pulses operating at a 10 Hz repetition rate. In addition to the investigation of elastic photon-photon scattering, this technique allows us to unveil or constrain new physics that could arise from the coupling of photons to yet undetected particles, therefore opening new avenues for searches of physics beyond the standard model.

Models of spin foam quantum gravity come in different spacetime signatures, either Euclidean or Lorentzian. The choice is reflected in the use of $Spin(4)$ or $SL(2,\mathbb{C})$ as gauge groups for the holonomies of the connection. In this work we show that a rotation of the Immirzi parameter to purely imaginary values maps the Euclidean Engle-Pereira-Rovelli-Livine spin foam model to its Lorentzian version and vice versa. Our methods provide a general recipe for relating spin foam models of different signature through analytic continuation of the gauge groups and their unitary irreducible representations.

We consider the thermoelectric properties of the mixed-dimensional quantum electrodynamics of the relativistic Dirac fermion and Wilson-Fisher boson. These models are self-dual, and can form nontrivial many-body phases depending on the values of chemical potential, background magnetic field and the electromagnetic fine-structure constant. Using particle-vortex duality, we derive a variety of thermoelectric relations for strongly interacting phases with classic paradigms such as the Wiedemann-Franz law and the Mott’s relation in the dual weakly interacting regimes. Besides, at the self-dual point, for the fermionic theory we find the ratio of thermal conductivity of electrical conductivity depends on the determinant of the Seebeck tensor and the phenomenological parameter Hall angle ${\theta }_H$. As for the bosonic theory, the dual fermion description explains how its Seebeck tensor varies depending on the dynamic regime characterized by ${\theta }_H$.

Gravitational wave echoes may provide a smoking gun signal for new physics in the immediate vicinity of black holes. As a quasiperiodic signal in time, echoes are characterized by the nearly constant time delay, and its precise measurement can help reveal a Planck-scale deviation outside of the would-be horizon. Different search methods have been developed for this quasiperiodic signal, while the searches suffer from large theoretical uncertainties of the echo waveform associated with the near-horizon physics. On the other hand, a coherent combination of a large number of pulses gives rise to a generic narrow resonance structure for the echo amplitude in frequency. This quasiperiodic pattern sets a complementary search target for echoes, and the time delay is inversely related to the average resonance spacing. A uniform comb has been proposed to look for the resonance structure in a rather model-independent way. In this paper, we develop a Bayesian algorithm to search for the resonance structure based on combs, where a phase-marginalized likelihood plays an essential role. The algorithm is validated with signal injections in detector noise from Advanced LIGO. With special treatments of the non-Gaussian artifacts, the noise outliers of the log Bayes factor distribution are properly removed. An echo signal not significantly below noise is detectable, and the time delay can be determined to very high precision. We perform the proposed search on real gravitational wave strain data of the first observing run of Advanced LIGO. We find no clear evidence of a comblike structure for GW150914 and GW151012.

We set up the Sugawara-Sommerfield (SS) construction and generalize it by the inclusion of canonical spin current. Using the techniques of current algebra, we infer that the canonical spin current are linear in the vector-axial vector currents. From a geometric perspective, the underlying manifold has a vanishing Lorentz curvature and a nonvanishing torsion. This leads to teleparallelism, and the canonical spin current (connection) assumes a pure gauge form. Moreover, this model provides a possibility to unify gravity with strong interactions by expressing the gravitational gauge connections in terms of the Yang-Mills gauge connections.

We construct Barrow holographic dark energy in the case of nonflat universe. In particular, considering closed and open spatial geometry we extract the differential equations that determine the evolution of the dark-energy density parameter, and we provide the analytical expression for the corresponding dark energy equation-of-state parameter. We show that the scenario can describe the thermal history of the universe, with the sequence of matter and dark energy epochs. Comparing to the flat case, where the phantom regime is obtained for relative large Barrow exponents, the incorporation of positive curvature leads the universe into the phantom regime for significantly smaller values. Additionally, in the case of negative curvature we find a reversed behavior, namely for increased Barrow exponent we acquire algebraically higher dark-energy equation-of-state parameters. Furthermore, we confront the scenario with Hubble parameter measurements and supernova type Ia data. Hence, the incorporation of slightly non-flat spatial geometry to Barrow holographic dark energy improves the phenomenology while keeping the new Barrow exponent to smaller values.

We go forward in completing the Standard Model of the Universe back in time with Planckian and trans-Planckian physics before inflation in agreement with observations, classical-quantum gravity duality, and quantum space-time. The quantum vacuum energy bends the space-time and produces a constant curvature de Sitter background. We link the de Sitter Universe and the cosmological constant to the (classical and quantum) harmonic oscillator. We find the quantum discrete cosmological levels: size, time, vacuum energy, Hubble constant, and gravitational (Gibbons-Hawking) entropy and temperature from the very early trans-Planckian vacuum to the classical vacuum energy today. For each level $n=0,1,2,\dots$, the two post- and pre-(trans)-Planckian phases are covered: In the post-Planckian Universe $t_{\text{planck}}\equiv t_P\le t\le {10}^{61}{t}_P$, the levels (in Planck units) are Hubble constant $H_n=1/\sqrt{(2n+1)}$, vacuum energy ${\mathrm{\Lambda }}_n=1/(2n+1)$, and entropy $S_n=(2n+1)$. As $n$ increases, radius, mass, and $S_n$ increase, $H_n$ and ${\mathrm{\Lambda }}_n$ decrease, and consistently the Universe classicalizes. In the pre-Planckian (trans-Planckian) phase ${10}^{-61}{t}_P\le t\le t_P$, the quantum levels are $H_{Qn}=\sqrt{(2n+1)}$, ${\mathrm{\Lambda }}_{Qn}=(2n+1)$, and $S_{Qn}=1/(2n+1)$, $Q$ denoting quantum. The $n$ levels cover all scales from the far past highest excited trans-Planckian level $n={10}^{122}$ with finite curvature, ${\mathrm{\Lambda }}_Q={10}^{122}$, and minimum entropy $S_Q={10}^{-122}$; $n$ decreases till the Planck level ($n=0$) with $H_{\text{planck}}=1={\mathrm{\Lambda }}_{\text{planck}}=S_{\text{planck}}$ and enters the post-Planckian phase, e.g., $n=1,2,\dots$, $n_{\mathrm{inflation}}={10}^{12},\dots$, $n_{\mathrm{cmb}}={10}^{114},\dots$, $n_{\text{reoin}}={10}^{118},\dots$, and $n_{\text{today}}={10}^{122}$, with the most classical value $H_{\text{today}}={10}^{-61}$, ${\mathrm{\Lambda }}_{\text{today}}={10}^{-122}$, and $S_{\text{today}}={10}^{122}$. We implement the Snyder-Yang algebra in this context, yielding a consistent group-theory realization of quantum discrete de Sitter space-time, classical-quantum gravity duality symmetry, and a clarifying unifying picture.

We revisit the geometrical meaning of statistical isotropy that is manifest in excursion sets of smooth random fields in two dimensions. Using the contour Minkowski tensor, ${\mathcal{W}}_1$, as our basic tool we first examine geometrical properties of single structures. For simple closed curves in two dimensions we show that ${\mathcal{W}}_1$ is proportional to the identity matrix if the curve has $m$-fold symmetry, with $m\ge 3$. Then we elaborate on how ${\mathcal{W}}_1$ maps any arbitrary shaped simple closed curve to an ellipse that is unique up to translations of its centroid. We also carry out a comparison of the shape parameters, $\alpha$ and $\beta$, defined using ${\mathcal{W}}_1$, with the filamentarity parameter defined using two scalar Minkowski functionals—area and contour length. We show that they contain complementary shape information, with ${\mathcal{W}}_1$ containing additional information of orientation of structures. Next, we apply our method to boundaries of excursion sets of random fields and examine what statistical isotropy means for the geometry of the excursion sets. Focusing on Gaussian isotropic fields, and using a seminumerical approach we quantify the effect of finite sampling of the field on the geometry of the excursion sets. In doing so we obtain an analytic expression for $\alpha$ which takes into account the effect of finite sampling. Finally we derive an analytic expression for the ensemble expectation of ${\mathcal{W}}_1$ for Gaussian anisotropic random fields. Our results provide insights that are useful for designing tests of statistical isotropy using cosmological data.

The constraint of trans-Planckian censorship conjecture on the brane inflation model is considered. The conjectures put an upper bound on the main parameter including temperature, inflation time, potential, and the tensor-to-scalar ratio parameter $r$. It is determined that the resulting constraint could be stronger than what we have for the standard inflationary models. The constraint, in general, depends on the brane tension and it is concluded that the conjecture also confined the value of brane tension to have consistency for the model. Confining the brane tension turns into a determining value for the five-dimensional Planck mass. The case of slowly varying Hubble parameter gives more interesting results for the $\epsilon$ and $r$, which indicates that the value of the tensor-to-scalar perturbation is not required to be extremely small.

Extragalactic foregrounds in cosmic microwave background (CMB) temperature maps lead to significant biases in CMB lensing reconstruction if not properly accounted for. Combinations of multifrequency data have been used to minimize the overall map variance (internal linear combination, or ILC), or specifically null a given foreground, but these are not tailored to CMB lensing. In this paper, we derive an optimal multifrequency combination to jointly minimize CMB lensing noise and bias. We focus on the standard lensing quadratic estimator, as well as the “shear-only” and source-hardened estimators, whose responses to foregrounds differ. We show that an optimal multifrequency combination is a compromise between the ILC and joint deprojection, which nulls the thermal Sunyaev-Zel’dovich (tSZ) and cosmic infrared background (CIB) contributions. In particular, for a Simons Observatory-like experiment with ${\ell }_{\max ,T}=3000$, we find that profile hardening alone (with the standard ILC) reduces the bias to the lensing power amplitude by 40%, at a 20% cost in noise, while the bias to the cross-correlation with a LSST-like sample is reduced by nearly an order of magnitude at a 10% noise cost, relative to the standard quadratic estimator. With a small amount of joint deprojection the bias to the profile hardened estimator can be further reduced to less than half the statistical uncertainty on the respective amplitudes, at a 20% and 5% noise cost for the auto- and cross-correlation respectively, relative to the profile hardened estimator with the standard ILC weights. Finally, we explore possible improvements with more aggressive masking and varying ${\ell }_{\max ,T}$.

This paper deals with the description of weak $B^{-}\to D^0,{\pi }^0$ and $D^{-}\to K^0,{\pi }^0$ transition form factors in both the space- and timelike momentum transfer regions, within a constituent-quark model. To this aim, neutrino-meson scattering and semileptonic weak decays are formulated within the framework of point-form relativistic quantum mechanics to end up with relativistic invariant process amplitudes from which meson transition currents and form factors are extracted in an unambiguous way. For spacelike momentum transfers, these form factors depend on the frame in which the $WM{M}^{\prime }$ vertex is considered. On physical grounds, such a frame dependence is expected from a pure valence-quark picture, since a complete, frame independent description of form factors is supposed to require valence as well as nonvalence contributions. Nonvalence contributions, the most important being the $Z$ graphs, are, however, suppressed in the infinite-momentum frame ($q^2<0$). On the other hand, they can play a significant role in the Breit frame ($q^2<0$) and in the direct decay calculation ($q^2>0$), as a comparison with the infinite-momentum-frame form factors (analytically continued to $q^2>0$) reveals. Numerical results for the analytically continued infinite-momentum-frame form factors are found to agree very well with lattice data in the timelike momentum transfer region, and also, the experimental value for the slope of the $F_{B\to D}^{+}$ transition form factor at zero recoil is reproduced satisfactorily. Furthermore, these predictions satisfy heavy-quark-symmetry constraints, and their $q^2$ dependence is well approximated by a pole fit, reminiscent of a vector-meson-dominance-like decay mechanism. We discuss how such a decay mechanism can be accommodated within an extension of our constituent-quark model, by allowing for a nonvalence component in the meson wave functions, and we also address the question of wrong cluster properties inherent in the formulation of relativistic quantum mechanics employed in this article.