We show that a recent interesting idea to circumvent the difficulties with the continuation of parton distribution functions to the Euclidean region, which consists in looking at equal time correlators between proton states of infinite momentum, encounters some problems related to the power divergent mixing pattern of deep inelastic scattering operators, when implemented within the lattice regularization.

The determination of the $CP$ nature of the Higgs coupling to top quarks is addressed in this paper, using $t\overline{t}h$ events produced in $\sqrt{s}=13\mathrm{TeV}$ proton-proton collisions at the LHC. Dileptonic final states are employed, with two oppositely charged leptons and four jets, corresponding to the decays $t\to b{W}^{+}\to b{\ell }^{+}{\nu }_{\ell }$, $\overline{t}\to \overline{b}{W}^{-}\to \overline{b}{\ell }^{-}{\overline{\nu }}_{\ell }$, and $h\to b\overline{b}$. Pure scalar ($h=H$), pure pseudoscalar ($h=A$), and $CP$-violating Higgs boson signal events, generated with MadGraph5_aMC@NLO, are fully reconstructed through a kinematic fit. We furthermore generate samples that have both a $CP$-even and a $CP$-odd component in the $t\overline{t}h$ coupling in order to probe the ratio of the two components. New angular distributions of the decay products, as well as $CP$ angular asymmetries, are explored in order to separate the scalar from the pseudoscalar components of the Higgs boson and reduce the contribution from the dominant irreducible background, $t\overline{t}b\overline{b}$. Significant differences between the angular distributions and asymmetries are observed, even after the full kinematic fit reconstruction of the events, allowing to define the best observables for a global fit of the Higgs couplings parameters.

By performing explicit computations of correlation functions, we find evidence that there is a sector of the two matrix model defined by the $SU(2)$ sector of $\mathcal{N}=4$ super Yang-Mills theory that can be reduced to eigenvalue dynamics. There is an interesting generalization of the usual Van der Monde determinant that plays a role. The observables we study are the Bogomol’nyi-Prasad-Sommerfield operators of the $SU(2)$ sector and include traces of products of both matrices, which are genuine multimatrix observables. These operators are associated with supergravity solutions of string theory.

In an analogy to the odd-dimensional case we define the parity anomaly as the part of the one-loop effective action for fermions associated with spectral asymmetry of the Dirac operator. This quantity is computed directly on four-dimensional manifolds with a boundary and related to the Chern-Simons current on the boundary. Despite a quite unusual Chern-Simons level obtained, the action is gauge invariant and passes all consistency checks.

This work deals with twinlike models that support topological structures such as kinks, vortices, and monopoles. We investigate the equations of motion and develop the first order framework to show how to build distinct models with the same solution and energy density, as required to make them twinlike models. We also investigate how the stability under small fluctuations behaves and introduce the conditions to get the same stability on general grounds. In particular, we study models that support kinks, vortices, and monopoles in one, two, and three spatial dimensions, respectively.

We analyze in detail the propagation of a minimally coupled massless scalar field in the gravitational background of a four-dimensional Einstein-Born-Infeld dilaton charged black hole. We obtain analytical expressions for the absorption cross section as well as the decay rate for the scalar field in the aforementioned spacetime, and we graphically show its behavior for different values of the free parameters of the theory.

To clarify certain nonlinear properties of strong gravitational field, we investigate cylindrically symmetric gravitational waves that are localized as regular wave packets in the space of radial and time coordinates. The waves are constructed by applying a certain kind of harmonic mapping method to the seed solutions with linear polarization, which are generalizations of the solution representing a cylindrical gravitational pulse wave discussed by Weber, Wheeler, and Bonnor. The solutions obtained here, though their form is rather simple, show occurrence of strong mutual conversion between a linear mode and a cross mode apparently. The single localized wave shows the conversion in the vicinity of the symmetric axis where the self-interaction is strengthened, and the collision between multiple waves also causes the conversion. These phenomena can be thought to be the emergence of genuine nonlinearity that the Einstein gravity holds. Finally we discuss a simple, but interesting application of the solutions to the case of the Einstein-Maxwell system.

In this article the study of four-dimensional spaces with NUT charges and their ground states is continued. In particular, through the introduction of an improved action principle containing topological densities, it is shown that these spaces have simple and sound thermodynamical relations. As an example, the entropy of the Taub-bolt-AdS solution is computed in terms of a Noether charge.

Given a spacetime with nonvanishing torsion, we discuss the equation for the evolution of the separation vector between infinitesimally close curves in a congruence. We show that the presence of a torsion field leads, in general, to tangent and orthogonal effects on the congruence; in particular, the presence of a completely generic torsion field contributes to a relative acceleration between test particles. We derive, for the first time in the literature, the Raychaudhuri equation for a congruence of timelike and null curves in a spacetime with the most generic torsion field.

The time evolution of matter fields in black hole exterior spacetimes is a well-studied subject, spanning several decades of research. However, the behavior of fields in the black hole interior spacetime has only relatively recently begun receiving some attention from the research community. In this paper, we numerically study the late-time evolution of scalar fields in both Schwarzschild and Kerr spacetimes, including the black hole interior. We recover the expected late-time power-law “tails” on the exterior (null infinity, timelike infinity, and the horizon). In the interior region, we find an interesting oscillatory behavior that is characterized by the multipole index $\ell$ of the scalar field. In addition, we also study the extremal Kerr case and find strong indications of an instability developing at the horizon.

It has recently been proved that horizonless compact stars with reflecting boundary conditions cannot support spatially regular matter configurations made of minimally coupled scalar fields, vector fields, and tensor fields. In the present paper we extend this intriguing no-hair property to the physically interesting regime of scalar fields with nonminimal coupling to gravity. In particular, we prove that static spherically symmetric configurations made of nonminimally coupled massless scalar fields cannot be supported by compact reflecting stars.

We obtain the exact (confluent Heun) solutions to the massive scalar field in a gravity’s rainbow Schwarzschild metric. With these solutions at hand, we study the Hawking radiation resulting from the tunneling rate through the event horizon. We show that the emission spectrum obeys nonextensive statistics and is halted when a certain mass remnant is reached. Next, we infer constraints on the rainbow parameters from recent LHC particle physics experiments and Hubble STIS astrophysics measurements. Finally, we study the low frequency limit in order to find the modified energy spectrum around the source.

We use a set of N-body simulations employing a modified gravity (MG) model with Vainshtein screening to study matter and halo hierarchical clustering. As test-case scenarios we consider two normal branch Dvali-Gabadadze-Porrati (nDGP) gravity models with mild and strong growth rate enhancement. We study higher-order correlation functions ${\xi }_n(R)$ up to $n=9$ and associated reduced cumulants $S_n(R)\equiv {\xi }_n(R)/\sigma (R{)}^{2n-2}$. We find that the matter probability distribution functions are strongly affected by the fifth force on scales up to $50h^{-1}\mathrm{Mpc}$, and the deviations from general relativity (GR) are maximized at $z=0$. For reduced cumulants $S_n$, we find that at small scales $R\le 6h^{-1}\mathrm{Mpc}$ the MG is characterized by lower values, with the deviation growing from 7% in the reduced skewness up to even 40% in $S_5$. To study the halo clustering we use a simple abundance matching and divide haloes into thee fixed number density samples. The halo two-point functions are weakly affected, with a relative boost of the order of a few percent appearing only at the smallest pair separations ($r\le 5h^{-1}\mathrm{Mpc}$). In contrast, we find a strong MG signal in $S_n(R)$’s, which are enhanced compared to GR. The strong model exhibits a $>3\sigma$ level signal at various scales for all halo samples and in all cumulants. In this context, we find that the reduced kurtosis to be an especially promising cosmological probe of MG. Even the mild nDGP model leaves a $3\sigma$ imprint at small scales $R\le 3h^{-1}\mathrm{Mpc}$, while the stronger model deviates from a GR signature at nearly all scales with a significance of $>5\sigma$. Since the signal is persistent in all halo samples and over a range of scales, we advocate that the reduced kurtosis estimated from galaxy catalogs can potentially constitute a strong MG-model discriminatory as well as GR self-consistency test.

We revisit the cosmological and astrophysical constraints on the fraction of the dark matter in primordial black holes (PBHs) with an extended mass function. We consider a variety of mass functions, all of which are described by three parameters: a characteristic mass and width and a dark matter fraction. Various observations then impose constraints on the dark matter fraction as a function of the first two parameters. We show how these constraints relate to those for a monochromatic mass function, demonstrating that they usually become more stringent in the extended case than the monochromatic one. Considering only the well-established bounds, and neglecting the ones that depend on additional astrophysical assumptions, we find that there are three mass windows, around $5\times {10}^{-16}{M}_{\odot }$, $2\times {10}^{-14}{M}_{\odot }$ and $25–100M_{\odot }$, where PBHs can constitute all the dark matter. However, if one includes all the bounds, PBHs can only constitute of order 10% of the dark matter.

The gravitational waves (GWs) from a binary black hole (BBH) with masses ${10}^4\lesssim M\lesssim {10}^7{\mathrm{M}}_{\odot }$ can be detected with the Laser Interferometer Space Antenna (LISA) once their orbital frequency exceeds ${10}^{-4}–{10}^{-5}\mathrm{Hz}$. The binary separation at this stage is $a=O(100)R_{\mathrm{g}}$ (gravitational radius), and the orbital speed is $v/c=O(0.1)$. We argue that at this stage, the binary will be producing bright electromagnetic (EM) radiation via gas bound to the individual BHs. Both BHs will have their own photospheres in x-ray and possibly also in optical bands. Relativistic Doppler modulations and lensing effects will inevitably imprint periodic variability in the EM light curve, tracking the phase of the orbital motion, and serving as a template for the GW inspiral waveform. Advanced localization of the source by LISA weeks to months prior to merger will enable a measurement of this EM chirp by wide-field x-ray or optical instruments. A comparison of the phases of the GW and EM chirp signals will help break degeneracies between system parameters, and probe a fractional difference $\mathrm{\Delta }v$ in the propagation speed of photons and gravitons as low as $\mathrm{\Delta }v/c\approx {10}^{-17}$.

The cosmic neutrino flux recently discovered by IceCube will be instrumental in probing the highest-energy astrophysical processes. Nevertheless, the origin of these neutrinos is still unknown. While it would be more straightforward to identify a transient, or galactic source, class, finding a population of distant, continuous sources is challenging. We introduce a source-type classification technique that incorporates all available information from catalogs of source candidates. We show that IceCube-Gen2 can statistically establish the origin of cosmic neutrinos, even for the most challenging source populations–starburst galaxies, AGN, or galaxy clusters–if neutrino track directions can be reconstructed with a precision $\sim {0.3}^{°}$. We further show that the source catalog out to $\sim 100\mathrm{Mpc}$ can be sufficient for the most challenging source types, allowing for more straightforward source surveys. We also characterize the role of detector properties, namely angular resolution, size, and veto power in order to understand the effects of IceCube-Gen2’s design specifics.

In the present work we study the gravitational effects of condensed dark matter on strange stars. We consider self-interacting dark matter particles with properties consistent with current observational constraints, and dark matter inside the star is modeled as a Bose-Einstein condensate. We integrate numerically the Tolman-Oppenheimer-Volkoff equations in the two-fluid formalism assuming that strange stars are made of up to 4 percent dark matter. It is shown that for a mass of the dark matter particles in the range 50–160 MeV strange stars are characterized by a maximum mass and radius similar to the ones found for neutron stars.

We analyze the chiral magnetic effect in a homogeneous neutral plasma from the point of view of energy conservation, and construct an effective potential for the growth of maximally helical perturbations of the electromagnetic field. We show that a negative curvature at the origin of the potential, indicating instability of the plasma, is induced by a chiral asymmetry in electron Fermi energy, as opposed to number density, while the potential grows at large field value. It follows that the ground state for a plasma has zero magnetic helicity; a nonzero electron mass will allow an excited state of a plasma with nonzero helicity to relax to that ground state quickly. We conclude that a chiral plasma instability triggered by weak interactions is not a viable mechanism for explaining magnetic fields in stars except possibly when dynamics drives the system far from equilibrium.

We propose a model with a two-Higgs doublet, where quark and charged-lepton masses in the first and second families are induced at one-loop level, and neutrino masses are induced at the two-loop level. In our model, we introduce an extra $U(1{)}_R$ gauge symmetry that plays a crucial role in achieving desired terms in no conflict with anomaly cancellation. We show the mechanism to generate fermion masses, the resultant mass matrices, and Yukawa interactions in mass eigenstates, and we discuss several interesting phenomenologies such as the muon anomalous magnetic dipole moment and the dark matter candidate that arise from this model.

We present an improved result for the lattice computation of the proton decay matrix elements in $N_f=2+1$ QCD. In this study, by adopting the error reduction technique of all-mode-averaging, a significant improvement of the statistical accuracy is achieved for the relevant form factor of proton (and also neutron) decay on the gauge ensemble of $N_f=2+1$ domain-wall fermions with $m_{\pi }=0.34–0.69\mathrm{GeV}$ on a $2.7{\mathrm{fm}}^3$ lattice, as used in our previous work [1]. We improve the total accuracy of matrix elements to 10–15% from 30–40% for $p\to \pi e^{+}$ or from 20–40% for $p\to K\overline{\nu }$. The accuracy of the low-energy constants $\alpha$ and $\beta$ in the leading-order baryon chiral perturbation theory (BChPT) of proton decay are also improved. The relevant form factors of $p\to \pi$ estimated through the “direct” lattice calculation from the three-point function appear to be 1.4 times smaller than those from the “indirect” method using BChPT with $\alpha$ and $\beta$. It turns out that the utilization of our result will provide a factor 2–3 larger proton partial lifetime than that obtained using BChPT. We also discuss the use of these parameters in a dark matter model.