The solutions of many issues, of the ongoing efforts to make deformed graphene a tabletop quantum field theory in curved spacetimes, are presented. A detailed explanation of the special features of curved spacetimes, originating from embedding portions of the Lobachevsky plane into ${\mathbf{R}}^3$, is given, and the special role of coordinates for the physical realizations in graphene is explicitly shown, in general, and for various examples. The Rindler spacetime is reobtained, with new important differences with respect to earlier results. The de Sitter spacetime naturally emerges, for the first time, paving the way to future applications in cosmology. The role of the Bañados, Teitelboim, and Zanelli (BTZ) black hole is also briefly addressed. The singular boundary of the pseudospheres, “Hilbert horizon,” is seen to be closely related to the event horizon of the Rindler, de Sitter, and BTZ kind. This gives new, and stronger, arguments for the Hawking phenomenon to take place. An important geometric parameter, $c$, overlooked in earlier work, takes here its place for physical applications, and it is shown to be related to graphene’s lattice spacing, $\ell$. It is shown that all surfaces of constant negative curvature, $\mathcal{K}=-r^{-2}$, are unified, in the limit $c/r\to 0$, where they are locally applicable to the Beltrami pseudosphere. This, and $c=\ell$, allow us (a) to have a phenomenological control on the reaching of the horizon; (b) to use spacetimes different from the Rindler spacetime for the Hawking phenomenon; and (c) to approach the generic surface of the family. An improved expression for the thermal LDOS is obtained. A nonthermal term for the total LDOS is found. It takes into account (i) the peculiarities of the graphene-based Rindler spacetime; (ii) the finiteness of a laboratory surface; and (iii) the optimal use of the Minkowski quantum vacuum, through the choice of this Minkowski-static boundary.

We calculate the Casimir energy-momentum tensor induced in a scalar field by a macroscopic ultrastatic spherically symmetric long-throated traversable wormhole, and examine whether this exotic matter is sufficient to stabilize the wormhole itself. The Casimir energy-momentum tensor is obtained (within the $\mathbb{R}\times S_2$ throat) by a mode sum approach, using a sharp energy cutoff and the Abel-Plana formula; Lorentz invariance is then restored by use of a Pauli-Villars regulator. The massless conformally coupled case is found to have a logarithmic divergence (which we renormalize) and a conformal anomaly, the thermodynamic relevance of which is discussed. Provided the throat radius is above some fixed length, the renormalized Casimir energy density is seen to be negative by all timelike observers, and almost all null rays; furthermore, it has sufficient magnitude to stabilize a long-throated wormhole far larger than the Planck scale, at least in principle. Unfortunately, the renormalized Casimir energy density is zero for null rays directed exactly parallel to the throat, and this shortfall prevents us from stabilizing the ultrastatic spherically symmetric wormhole considered here. Nonetheless, the negative Casimir energy does allow the wormhole to collapse extremely slowly, its lifetime growing without bound as the throat length is increased. We find that the throat closes slowly enough that its central region can be safely traversed by a pulse of light.

Ground-based gravitational wave detectors are sensitive to a narrow range of frequencies, effectively taking a snapshot of merging compact-object binary dynamics just before merger. We demonstrate that by adopting analysis parameters that naturally characterize this “picture,” the physical parameters of the system can be extracted more efficiently from the gravitational wave data and interpreted more easily. We assess the performance of Markov chain Monte Carlo parameter estimation in this physically intuitive coordinate system, defined by (a) a frame anchored on the binary’s spins and orbital angular momentum and (b) a time at which the detectors are most sensitive to the binary’s gravitational wave emission. Using anticipated noise curves for the advanced-generation LIGO and Virgo gravitational wave detectors, we find that this careful choice of reference frame and reference time significantly improves parameter estimation efficiency for binary neutron stars, neutron star–black hole, and binary black hole signals.

Spherical scalar collapse in $f(R)$ gravity is studied numerically in double-null coordinates in Einstein frame. Dynamics in the vicinity of the singularity of the formed black hole is examined via mesh refinement and asymptotic analysis. Before the collapse, the scalar degree of freedom $f^{\prime }$ is coupled to a physical scalar field, and general relativity is restored. During the collapse, the major energy of the physical scalar field moves to the center. As a result, $f^{\prime }$ loses the coupling and becomes light, and gravity transits from general relativity to $f(R)$ gravity. Due to strong gravity from the singularity and the low mass of $f^{\prime }$, $f^{\prime }$ will cross the minimum of the potential and approach zero. Therefore, the dynamical solution is significantly different from the static solution of the black hole in $f(R)$ gravity—it is not the de Sitter-Schwarzschild solution as one might have expected. $f^{\prime }$ tries to suppress the evolution of the physical scalar field, which is a dark energy effect. As the singularity is approached, metric terms are dominant over other terms. The Kasner solution for spherical scalar collapse in $f(R)$ theory is obtained and confirmed by numerical results. These results support the Belinskii-Khalatnikov-Lifshitz conjecture well.

Theories with Planck-scale-deformed symmetries exhibit quantum time evolution in which purity of the density matrix is not preserved. In particular we show that the nontrivial structure of momentum space of these models is reflected in a deformed action of translation generators on operators. Such action in the case of time-translation generators leads to a Lindblad-like evolution equation for density matrices when expanded at leading order in the Planckian deformation parameter. This evolution equation is covariant under the deformed realization of Lorentz symmetries characterizing these models.

A five-parametric exact solution, describing a binary system composed of identical counterrotating black holes endowed with opposite electromagnetic charges, is constructed. The addition of the angular momentum parameter to the static Emparan-Teo dihole model introduces magnetic charges into this two-body system. The solution can be considered as an extended model for describing generalized black diholes as dyons. We derive the explicit functional form of the horizon half-length parameter $\sigma$ as a function of the Komar parameters: Komar mass $M$, electric/magnetic charge $Q_E/Q_B$, angular momentum $J$, and a coordinate distance $R$, where $Q_E<0$, $J>0$ for the upper constituent and $Q_E>0$, $J<0$ for the lower one. The addition of magnetic charges enhances the standard Smarr mass formula in order to take into account their contribution to the mass. The solution contains, as particular cases, two solutions already discussed in the literature.

We will consider the torsional completion of gravity for a background filled with Dirac matter fields, studying what happens when fermionic nonminimal coupling is taken into account: we will show that, although nonminimal couplings are usually disregarded because of their ill-defined behavior in ultraviolet regimes, this is due to the fact that torsion is commonly neglected, whereas when torsion is not left aside, even nonminimal couplings behave properly. In detail, we will see that nonminimal coupling allows one to renormalize the Dirac equation even when torsion is taken into consideration and that in some type of nonminimally coupled models parity oddness might be present even in the gravitational sector. In addition, we will show that in the presence of the considered nonminimal coupling, torsion is able to evade cosmological singularities as it can happen in the minimal coupling case and in some other nonminimally coupled theory. In the course of the paper, we shall consider a specific interaction as prototype to study this fermionic nonminimal coupling, but we will try to present results that do not depend on the actual structure of the nonminimal couplings by investigating alternative types of interaction.

Charge carriers moving at the speed of light along a straight, superconducting cosmic string carry with them a logarithmically divergent slab of electromagnetic field energy. Thus, no finite local input can induce a current that travels unimpeded to infinity. Rather, electromagnetic backreaction must damp this current asymptotically to nothing. We compute this backreaction and find that the electromagnetic fields and currents decline exactly as rapidly as necessary to prevent a divergence. We briefly discuss the corresponding gravitational situation.

In performing cosmological $N$-body simulations, it is widely appreciated that the growth of structure on the largest scales within a simulation box will be inhibited by the finite size of the simulation volume. Following ideas set forth by Seto Astrophys. J. 523, 24 (1999), this paper shows that standard (also known as one-loop) cosmological perturbation theory (SPT) [E. T. Vishniac, Mon. Not. R. Astron. Soc. 203, 345 (1983)] can be used to predict, in an approximate way, the deleterious effect of the box scale on the power spectrum of density fluctuations in simulation volumes. Alternatively, this approach can be used to quickly estimate post facto the effect of the box scale on power spectrum results from existing simulations. In this way SPT can help determine whether larger box sizes or other more-sophisticated methods are needed to achieve a particular level of precision for a given application (e.g. simulations to measure the nonlinear evolution of baryon acoustic oscillations). I focus on SPT in this paper and show that its predictions differ only by about a factor of 2 or less from the measured suppression inferred from both power law and $\mathrm{\Lambda }\mathrm{CDM}$ $N$-body simulations. It should be possible to improve the accuracy of these predictions through using more-sophisticated perturbation theory models. An Appendix compares power spectrum measurements from the power law simulations at outputs where box-scale effects are minimal to perturbation theory models and previously published fitting functions. These power spectrum measurements are included with this paper to aid efforts to develop new perturbation theory models.

We study structure formation in K-mouflage cosmology whose main feature is the absence of screening effect on quasilinear scales. We show that the growth of structure at the linear level is affected by both a new time dependent Newton constant and a friction term which depend on the background evolution. These combine with the modified background evolution to change the growth rate by up to ten percent since $z\sim 2$. At the one loop level, we find that the nonlinearities of the K-mouflage models are mostly due to the matter dynamics and that the scalar perturbations can be treated at tree level. We also study the spherical collapse in K-mouflage models and show that the critical density contrast deviates from its $\mathrm{\Lambda }$-CDM value and that, as a result, the halo mass function is modified for large masses by an order one factor. Finally we consider the deviation of the matter spectrum from $\mathrm{\Lambda }$-CDM on nonlinear scales where a halo model is utilized. We find that the discrepancy peaks around $1h{\text{Mpc}}^{-1}$ with a relative difference which can reach fifty percent. Importantly, these features are still true at larger redshifts, contrary to models of the chameleon-$f(R)$ and Galileon types.

We study the cosmology of K-mouflage theories at the background level. We show that the effects of the scalar field are suppressed at high matter density in the early Universe and only play a role in the late time Universe where the deviations of the Hubble rate from its $\mathrm{\Lambda }$-CDM counterpart can be of the order five percent for redshifts $1\lesssim z\lesssim 5$. Similarly, we find that the equation of state can cross the phantom divide in the recent past and even diverge when the effective scalar energy density goes negative and subdominant compared to matter, preserving the positivity of the squared Hubble rate. These features are present in models for which big bang nucleosynthesis is not affected. We analyze the fate of K-mouflage when the nonlinear kinetic terms give rise to ghosts, particle excitations with negative energy. In this case, we find that the K-mouflage theories can only be considered as an effective description of the Universe at low energy below 1 keV. In the safe ghost-free models, we find that the equation of state always diverges in the past and changes significantly by a few percent since $z\lesssim 1$.

We study high-energy neutrino production in inner jets of radio-loud active galactic nuclei (AGN), taking into account effects of external photon fields and the blazar sequence. We show that the resulting diffuse neutrino intensity is dominated by quasar-hosted blazars, in particular, flat spectrum radio quasars, and that PeV-EeV neutrino production due to photohadronic interactions with broadline and dust radiation is unavoidable if the AGN inner jets are ultrahigh-energy cosmic-ray (UHECR) sources. Their neutrino spectrum has a cutoff feature around PeV energies since target photons are due to $\mathrm{Ly}\alpha$ emission. Because of infrared photons provided by the dust torus, neutrino spectra above PeV energies are too hard to be consistent with the IceCube data unless the proton spectral index is steeper than 2.5, or the maximum proton energy is $\lesssim 100\mathrm{PeV}$. Thus, the simple model has difficulty in explaining the IceCube data. For the cumulative neutrino intensity from blazars to exceed $\sim {10}^{-8}\mathrm{GeV}{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}{\mathrm{sr}}^{-1}$, their local cosmic-ray energy generation rate would be $\sim 10–100$ times larger than the local UHECR emissivity but is comparable to the averaged $\gamma$-ray blazar emissivity. Interestingly, future detectors such as the Askaryan Radio Array can detect $\sim 0.1–1\mathrm{EeV}$ neutrinos even in more conservative cases, allowing us to indirectly test the hypothesis that UHECRs are produced in the inner jets. We find that the diffuse neutrino intensity from radio-loud AGN is dominated by blazars with $\gamma$-ray luminosity of $\gtrsim 10^{48}\mathrm{erg}{\mathrm{s}}^{-1}$, and the arrival directions of their $\sim 1–100\mathrm{PeV}$ neutrinos correlate with the luminous blazars detected by Fermi.

We compile a list of 14 independent measurements of a large-scale structure growth rate between redshifts $0.067\le z\le 0.8$ and use this to place constraints on model parameters of constant and time-evolving general-relativistic dark energy cosmologies. With the assumption that gravity is well modeled by general relativity, we discover that growth-rate data provide restrictive cosmological parameter constraints. In combination with type Ia supernova apparent magnitude versus redshift data and Hubble parameter measurements, the growth rate data are consistent with the standard spatially flat $\mathrm{\Lambda }\mathrm{CDM}$ model, as well as with mildly evolving dark energy density cosmological models.

We discuss a nonlocal modification of gravity obtained adding a term $m^{2}R{\square }^{-2}R$ to the Einstein-Hilbert action. We find that the mass parameter $m$ only affects the nonradiative sector of the theory, while the graviton remains massless, there is no propagating ghostlike degree of freedom, no vDVZ discontinuity, and no Vainshtein radius below which the theory becomes strongly coupled. For $m=\mathcal{O}(H_0)$ the theory therefore recovers all successes of GR at solar system and lab scales, and only deviates from it at cosmological scales. We examine the cosmological consequences of the model and we find that it automatically generates a dynamical dark energy and a self-accelerating evolution. After fixing our only free parameter $m$ so to reproduce the observed value of the dark energy density today, we get a pure prediction for the dark energy equation of state, $w_{\mathrm{DE}}\simeq -1.14$. This value is consistent with the existing data, and could also resolve the possible tension between the Planck data and local measurements of the Hubble parameter.

Searches for gravitational-wave transients from binary black hole coalescences typically rely on one of two approaches: matched filtering with templates and morphology-independent excess power searches. Multiple algorithmic implementations in the analysis of data from the first generation of ground-based gravitational-wave interferometers have used different strategies for the suppression of non-Gaussian noise transients and have targeted different regions of the binary black hole parameter space. In this paper we compare the sensitivity of three such algorithms: matched filtering with full coalescence templates, matched filtering with ringdown templates, and a morphology-independent excess power search. The comparison is performed at a fixed false alarm rate and relies on Monte Carlo simulations of binary black hole coalescences for spinning, nonprecessing systems with a total mass of $25–350{\mathrm{M}}_{\odot }$, which covers a portion of the parameter space of stellar mass and intermediate mass black hole binaries. We find that in the mass range of $25–100{\mathrm{M}}_{\odot }$, the sensitive distance of the search, marginalized over source parameters, is the best with matched filtering to full waveform templates, which is within 10% of the next most sensitive search of morphology-independent excess power algorithm, at a false alarm rate of 3 events/year. In the mass range of $100–350{\mathrm{M}}_{\odot }$, the same comparison favors the morphology-independent excess power search within 20% of matched filtering with ringdown templates. The dependence on mass and spin is also explored.

We consider direct bounds on the coefficients of higher-dimensional top quark dipole operators from their contributions to anomalous top couplings that affect some related processes at the LHC. Several observables are studied. In particular, we incorporate for the first time in this type of analysis the recently measured associated $t\overline{t}V$ production, which is currently the only measured direct observable sensitive to the dipole operator involving the hypercharge field. We perform a Bayesian analysis to derive the $1(2)\sigma$ confidence level intervals on these coefficients.

We analyze the classical stability of $Q$-tubes—charged extended objects in $(3+1)$-dimensional complex scalar field theory. Explicit solutions were found analytically in the piecewise parabolic potential. Our choice of potential allows us to construct a powerful method of stability investigation. We check that in the case of the zero winding number $n=0$, the previously known stability condition ${\partial }^{2}E/\partial Q^2<0$ for $Q$-balls is fulfilled. However, in the case $n\ge 1$, we find a continuous family of instabilities. Our result has an analogy with the theory of superconductivity of the second type, in which the vortex with $n>1$ becomes unstable towards the decay into the $n$ vortices with the single winding number.

The baryon to photon ratio in the present Universe is very accurately measured to be $(6.065\pm 0.090)\times {10}^{-10}$. We study the possible origin of this baryon asymmetry in the neutrino sector through the generic mechanism of baryogenesis through leptogenesis. We consider both the type I and type II seesaw origin of neutrino masses within the framework of left-right symmetric models (LRSM). Using the latest best-fit global neutrino oscillation data of mass squared differences, mixing angles and Dirac $CP$ phase, we compute the predictions for baryon to photon ratio keeping the Majorana $CP$ phases as free parameters for two different choices of lightest neutrino mass eigenvalue for both normal and inverted hierarchical patterns of neutrino masses. We do our calculation with and without lepton flavor effects being taken into account. We choose different diagonal Dirac neutrino mass matrix for different flavor effects in such a way that the lightest right-handed neutrino mass is in the appropriate range. We also study the predictions for baryon asymmetry when the neutrino masses arise from a combination of both type I and type II seesaw (with dominating type I term) and discriminate between several combinations of Dirac and Majorana $CP$ phases by demanding successful predictions for baryon asymmetry.

We compute the nuclear corrections to the proton-deuteron Drell-Yan cross section for inclusive dilepton production, which, when combined with the proton-proton cross section, is used to determine the flavor asymmetry in the proton sea, $\overline{d}\ne \overline{u}$. In addition to nuclear smearing corrections that are known to be important at large values of the nucleon’s parton momentum fraction $x_N$, we also consider dynamical off-shell nucleon corrections associated with the modifications of the bound nucleon structure inside the deuteron, which we find to be significant at intermediate and large $x_N$ values. We also provide estimates of the nuclear corrections at kinematics corresponding to existing and planned Drell-Yan experiments at Fermilab and J-PARC which aim to determine the $\overline{d}/\overline{u}$ ratio for $x\lesssim 0.6$.

The mass spectra of the $D_s$ meson is obtained in the framework of the relativistic independent quark model using a Martin-like potential for the quark confinement. The predicted excited states are in good agreement with the experimental results as well as with the lattice and other theoretical predictions. The spectroscopic parameters are employed further to compute the decay constant, electromagnetic transition and leptonic decay widths. The present result for its decay constant, $f_P$ (252.82 MeV) is in excellent agreement with the value $252.6\pm 11.1\mathrm{MeV}$ reported by CLEO-c. The predicted branching ratios for $(D_s\to \tau {\overline{\nu }}_{\tau },\mu {\overline{\nu }}_{\mu })$ ($5.706\times 10^{-2},5.812\times 10^{-3}$) are in close agreement with the values [$(5.43\pm 0.31)\times 10^{-2},(5.90\pm 0.33)\times 10^{-3}$] reported in Particle Data Group. The Cabibbo favored semileptonic branching ratio of $[D_s\to \varphi e^{+}{\nu }_e(2.01\%)]$ and that of the hadronic decay $[D_s\to \varphi {\pi }^{+}(4.62\%)]$ are in very good agreement with the respective Particle Data Group values, and the branching ratio $[D_s\to K^0{\pi }^{+}(2.16\times 10^{-3})]$ is in very good agreement with the branching ratio of $(2.40\pm 0.18)\times 10^{-3}$ reported by Belle collaboration.