In the framework of the Einstein-Maxwell-axion theory, we consider a static field configuration in the outer zone of a magnetic star. We assume that this field configuration is formed by the following interacting quartet: a spherically symmetric gravitational field of the Reissner-Nordström type, pseudoscalar field, associated with an axionic dark matter, strong intrinsic magnetic field, and axionically induced electric field. Based on the analysis of the solutions to the master equations of the model, we show that the structure of the formed field configuration reveals the following triple effect. First, if the strong magnetic field of the star has the dipole component, the axionic halo around the magnetic star with spherically symmetric gravitational field is no longer spheroidal, and the distortion is induced by the axion-photon coupling. Second, due to the distortion of the axionic halo, the magnetic field is no longer pure dipolar, and the induced quadruple, octupole, etc., components appear, thus redistributing the magnetic energy between the components with more steep radial profiles than the dipolar one. Third, the interaction of the axionic and magnetic fields produces the electric field, which inherits their multipole structure. We attract attention to possible applications of the predicted field restructuring to the theory of axionic rotating magnetars.

We propose a simple $SU(5)$ model that connects the neutrino mass generation mechanism to the observed disparity between the masses of charged leptons and down-type quarks. The model is built out of 5-, 10-, 15-, 24-, and 35-dimensional representations of $SU(5)$ and comprises two (three) $3\times 3$ ($3\times 1$) Yukawa coupling matrices to accommodate all experimentally measured fermion masses and mixing parameters. The gauge coupling unification considerations, coupled with phenomenological constraints inferred from experiments that probe neutrino masses and mixing parameters and/or look for proton decay, fix all relevant mass scales of the model. The proposed scenario places several multiplets at the scales potentially accessible at the LHC and future colliders and correlates this feature with the gauge-boson-mediated proton decay signatures. It also predicts that one neutrino is massless.

We investigate the singularity structure of the $(-1{)}^F$ graded partition function in QCD with $n_f\ge 1$ massive adjoint fermions in the large-$N$ limit. Here, $F$ is fermion number and $N$ is the number of colors. The large $N$ partition function is made reliably calculable by taking space to be a small three-sphere $S^3$. Singularities in the graded partition function are related to phase transitions and to Hagedorn behavior in the $(-1{)}^F$-graded density of states. We study the flow of the singularities in the complex “inverse temperature” $\beta$ plane as a function of the quark mass. This analysis is a generalization of the Lee-Yang-Fisher-type analysis for a theory which is always in the thermodynamic limit thanks to the large $N$ limit. We identify two distinct mechanisms for the appearance of physical Hagedorn singularities and center-symmetry changing phase transitions at real positive $\beta$, inflow of singularities from the $\beta =0$ point, and collisions of complex conjugate pairs of singularities.

In a previous paper we proposed a factorization principle for the correlation functions of Berenstein-Maldacena-Nastase (BMN) operators in free $\mathcal{N}=4$ super-Yang-Mills theory. These correlators are conjectured to described physical string amplitudes in an infinitely curved Ramond-Ramond pp-wave background. There was a puzzle that the factorization seems to break down for the $S$ channel in the $2\to 2$ scattering process. Here we resolve this puzzle by including some diagrams missed in the previous paper. We also observe some interesting relations which further support the interpretation of higher genus correlators as physical string loop amplitudes.

The full description of a superconductor requires that it has an infinite dc conductivity (or zero electrical resistivity) as well as expels the external magnetic fields. Thus, for any holographic superconductor which is dual to a real superconductor, it is necessary to examine, simultaneously, these two features based on the gauge/gravity duality. In this paper, we explore numerically these two aspects of the higher dimensional holographic superconductors, in the presence of a power-Maxwell electrodynamics as the gauge field. At first, we calculate the critical temperature, condensation, conductivity, and superconducting gap, in the absence of magnetic field and disclose the effects of both power parameter, $s$, as well as the spacetime dimensions, $d$, on this quantities. Then, we immerse the superconductor into an external magnetic field, $B$, and observe that with increasing the magnetic field, the starting point of condensation occurs at temperature less than the critical temperature, $T_c$, in the absence of magnetic field. This implies that at a fixed temperature, we can define a critical magnetic field, above which the critical temperature goes to zero which is similar to the Meissner effect in superconductor. In these indications, we also try to show the distinction of the conformal invariance of the power-Maxwell Lagrangian that occurs for $s=d/4$.

In this paper two issues are addressed. First, we discuss renormalization properties of a class of gauged linear sigma models (GLSM), which reduce to $\mathbb{W}\mathbb{C}\mathbb{P}(\mathit{N},\tilde{\mathit{N}})$ nonlinear sigma models (NLSM) in the low-energy limit. Sometimes they are referred to as the Hanany-Tong models. If supersymmetry is $\mathcal{N}=(2,2)$ the ultraviolet-divergent logarithm in GLSM appears, in the renormalization of the Fayet-Iliopoulos parameter, and is exhausted by a single tadpole graph. This is not the case in the daughter NLSMs. As a result, the one-loop renormalizations are different in GLSMs and their daughter NLSMs. We explain this difference and identify its source. In particular, we show why at $N=\tilde{N}$ there is no UV logarithm in the parent GLSM, while they do appear in the corresponding NLSM. In the second part of the paper we discuss the same problem for a class of $\mathcal{N}=(0,2)$ GLSMs considered previously. In this case renormalization is not limited to one loop; all orders exact $\beta$ functions for GLSMs are known. We discuss logarithmically divergent loops at one- and two-loop levels.

We extend previous work on quantum stress tensor operators which have been averaged over finite time intervals to include averaging over finite regions of space as well. The space and time averaging can be viewed as describing a measurement process for a stress tensor component, such as the energy density of a quantized field in its vacuum state. Although spatial averaging reduces the probability of large vacuum fluctuations compared to time averaging alone, we find that the probability distribution decreases more slowly than exponentially as the magnitude of the measured energy density increases. This implies that vacuum fluctuations can sometimes dominate over thermal fluctuations and potentially have observable effects.

This paper is a companion of J. M. Fernández Tío and G. Dotti, Phys. Rev. D 95, 124041 (2017), in which, following a program on black hole nonmodal linear stability initiated in G. Dotti, Phys. Rev. Lett. 112, 191101 (2013), odd perturbations of the Einstein-Maxwell equations around a Reissner-Nordström (A)dS black hole were analyzed. Here we complete the proof of the nonmodal linear stability of this spacetime by analyzing the even sector of the linear perturbations. We show that all the gauge invariant information in the metric and Maxwell field even perturbations is encoded in two spacetime scalars: $\mathcal{S}$, which is a gauge invariant combination of $\delta (C_{\alpha \beta \gamma \epsilon }{C}^{\alpha \beta \gamma \epsilon })$ and $\delta (C_{\alpha \beta \gamma \delta }{F}_{\alpha \beta }{F}^{\gamma \delta })$, and $\mathcal{T}$, a gauge invariant combination of $\delta ({\nabla }_{\mu }{F}_{\alpha \beta }{\nabla }^{\mu }{F}^{\alpha \beta })$ and $\delta ({\nabla }_{\mu }{C}_{\alpha \beta \gamma \delta }{\nabla }^{\mu }{C}^{\alpha \beta \gamma \delta })$. Here $C_{\alpha \beta \gamma \delta }$ is the Weyl tensor, $F_{\alpha \beta }$ the Maxwell field, and $\delta$ means first order variation. We prove that $\mathcal{S}$ and $\mathcal{T}$ are in one-one correspondence with gauge classes of even linear perturbations, and that the linearized Einstein-Maxwell equations imply that these scalar fields are pointwise bounded on the outer static region.

Novel wormholes are obtained in Einstein-scalar-Gauss-Bonnet theory for several coupling functions. The wormholes may feature a single- or a double-throat geometry and do not demand any exotic matter. The scalar field may asymptotically vanish or be finite, and it may possess radial excitations. The domain of existence is fully mapped out for various forms of the coupling function.

Gravitational-wave (GW) observations of binary black holes offer the best probes of the relativistic, strong-field regime of gravity. Gravitational radiation in the leading order is quadrupolar. However, nonquadrupole (higher order) modes make appreciable contribution to the radiation from binary black holes with large mass ratios and misaligned spins. The multipolar structure of the radiation is fully determined by the intrinsic parameters (masses and spin angular momenta of the companion black holes) of a binary in quasicircular orbit. Following our previous work [S. Dhanpal, A. Ghosh, A. K. Mehta, P. Ajith, and B. S. Sathyaprakash, Phys. Rev. D 99, 104056 (2019).], we develop multiple ways of testing the consistency of the observed GW signal with the expected multipolar structure of radiation from binary black holes in general relativity. We call this a no-hair test of binary black holes as this is similar to testing the no-hair theorem for isolated black holes through mutual consistency of the quasinormal mode spectrum. We use Bayesian inference on simulated GW signals that are consistent/inconsistent with binary black holes in general relativity to demonstrate the power of the proposed tests. We also make estimate systematic errors arising as a result of neglecting companion spins.

We investigate the formation of primordial black holes (PBHs) from the collapse of spherically symmetric domain wall bubbles, which spontaneously nucleate via quantum tunneling during inflation. Since the tension of domain walls changes with time and so domain walls nucleate in a short time interval, the mass function of PBHs in general has a spikelike structure. In contrast to models in which PBHs are produced from overdense regions, our model avoids the uncertainties of the PBHs production mechanism. PBHs from domain walls with mass around ${10}^{20}\mathrm{g}$ may constitute all dark matter, and those with mass around ${10}^{34}\mathrm{g}$ can explain the merger events of binary black holes detected by LIGO.

The late integrated Sachs-Wolfe (ISW) effect correlates the cosmic microwave background (CMB) temperature anisotropies with foreground cosmic large-scale structures. As the correlation depends crucially on the growth history in the era of dark energy, it is a key observational probe for constraining the cosmological model. Here we present a detailed study based on full-sky and deep light cones generated from very large volume numerical N-body simulations, which allow us to avoid the use of standard replica techniques, while capturing the entirety of the late ISW effect on the large scales. We postprocess the light cones using an accurate ray-tracing method and construct full-sky maps of the ISW temperature anisotropy for three different dark energy models. We quantify in detail the extent to which the ISW effect can be used to discriminate between different dark energy scenarios when cross-correlated with the matter distribution or the CMB lensing potential. We also investigate the onset of nonlinearities, the so-called Rees-Sciama effect which provides a complementary probe of the dark sector. We find the signal of the lensing-lensing and ISW-lensing correlation of the three dark energy models to be consistent with measurements from the Planck satellite. Future surveys of the large-scale structures may provide cross-correlation measurements that are sufficiently precise to distinguish the signal of these models. Our methodology is very general and can be applied to any dark energy or modified gravity scenario as long as the metric seen by photons can still be characterized by a Weyl potential.

The quasispherical Szekeres metric is an exact solution to Einstein’s equations describing an inhomogeneous and anisotropic cosmology. Though its governing equations are well known, there are subtle, often-overlooked details in how the model’s functions relate to its physical layout, including the shapes and relative positions of structures. We present an illustrated overview of the quasispherical Szekeres models and show exactly how the model functions relate to the physical shape and distribution of matter. In particular, we describe a shell rotation effect that has not previously been fully understood. We show how this effect relates to other known properties, and lay out some mathematical tools useful for constructing models and picturing them accurately.

We show that the coherent axion field spontaneously decays by emitting axion particles via quantum tunneling if axion potential has more than one minimum. By employing the $\hslash$ expansion and mean field approximation, we develop a formalism to trace the real-time dynamics of the axion particle production including its backreaction to the coherent axion field. We also present numerical results for the time evolution of various physical quantities including the strength of the coherent axion field, phase-space density of produced axion particles, energy density, and pressure. Phenomenological implications of our results are also discussed.

Hints for the existence of a sterile neutrino at nuclear reactors are reexamined using two updated predictions for the fluxes of antineutrinos produced in fissions. These new predictions diverge in their preference for the rate deficit anomaly, relative to previous analyses, but the anomaly in the ratios of measured antineutrino spectra persists. We comment on upcoming experiments and their ability to probe the preferred region of the sterile-neutrino parameter space in the electron neutrino disappearance channel.

We study Cabibbo-favored (CF) and singly Cabibbo-suppressed (SCS) two-body hadronic weak decays of the antitriplet charmed baryons ${\mathrm{\Lambda }}_c^{+}$, ${\mathrm{\Xi }}_c^0$, and ${\mathrm{\Xi }}_c^{+}$ with more focus on the last two. Both factorizable and nonfactorizable contributions are considered in the topologic diagram approach. The estimation of nonfactorizable contributions from $W$-exchange and inner $W$-emission diagrams relies on the pole model and current algebra. The nonperturbative parameters in both factorizable and nonfactorizable parts are calculated in the MIT bag model. Branching fractions and up-down decay asymmetries for all the CF and SCS decays of antitriplet charmed baryons are presented. The prediction of $\mathcal{B}({\mathrm{\Xi }}_c^{+}\to {\mathrm{\Xi }}^0{\pi }^{+})$ agrees well with the measurements inferred from Belle and CLEO, while the calculated $\mathcal{B}({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^{-}{\pi }^{+})$ is too large compared to the recent Belle measurement. We conclude that these two ${\mathrm{\Xi }}_c\to \mathrm{\Xi }{\pi }^{+}$ modes cannot be simultaneously explained within the current-algebra framework for $S$-wave amplitudes. This issue needs to be resolved in future study. The long-standing puzzle with the branching fraction and decay asymmetry of ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Xi }}^0{K}^{+}$ is resolved by noting that only the type-II $W$-exchange diagram contributes to this mode. We find that not only does the calculated rate agree with experiment but also the predicted decay asymmetry is consistent with the SU(3)-flavor symmetry approach in sign and magnitude. Likewise, the CF mode ${\mathrm{\Xi }}_c^0\to {\mathrm{\Sigma }}^{+}{K}^{-}$ and the SCS decays ${\mathrm{\Xi }}_c^0\to p{K}^{-}$, ${\mathrm{\Sigma }}^{+}{\pi }^{-}$ proceed only through type-II $W$ exchange. They are predicted to have large and positive decay asymmetries. These features can be tested in the near future.

The phase diagram of the two-dimensional Nambu–Jona-Lasinio model with isospin is explored in the large $N_c$ limit with semiclassical methods. We consider finite temperature and include chemical potentials for all conserved charges. In the chiral limit, a full analytical solution is presented, expressed in terms of known results for the single-flavor Gross-Neveu and Nambu–Jona-Lasinio models. A novel crystalline structure appears and is shown explicitly to be thermodynamically more stable than the homogeneous phase at zero temperature. If we include a bare fermion mass, the problem reduces again to solved problems in one-flavor models provided that either the fermionic or the isospin chemical potentials vanish. In the general case, a stability analysis is used to construct the perturbative phase boundary between homogeneous and inhomogeneous phases. This is sufficient to get a good overview of the complete phase diagram. Missing nonperturbative phase boundaries requiring a full numerical Hartree-Fock calculation will be presented in future work.

Using the general form of the generalized Bethe-Salpeter wave functions for four-quark states describing the meson-meson molecular structure given in our previous work, we obtain the general formulas for the decay widths of molecular states composed of two vector mesons with arbitrary spin and parity into two photons. Then, this general formalism is applied to investigate the radiative two-photon decay of the observed $X(3915)$ state, in which this exotic state $X(3915)$ is considered as a mixed state of two components $D^{*0}{\overline{D}}^{*0}$ and $D^{*+}{D}^{*-}$. The numerical result of decay mode $X(3915)\to \gamma \gamma$ is consistent with the experimental values.

The COMPASS collaboration published precise data on production cross section of charged hadrons in lepton-hadron semi-inclusive deep inelastic scattering, showing almost an order of magnitude larger than next-to-leading order QCD calculations when $P_{h_T}$ and $z_h$ are sufficiently large. We explore the role of power corrections to the theoretical calculations, and quantitatively demonstrate that the power corrections are extremely important for these data when the final-state multiplicity is low and the production kinematics is near the edge of phase space. Our finding motivates more detailed studies on power corrections for upcoming experiments at Jefferson Lab, as well as the future Electron-Ion Collider.

Quantum field theory in zero spatial dimensions has a rich infrared landscape and a universal ultraviolet, inverting the usual Wilsonian paradigm. For holographic theories this implies a rich landscape of asymptotically ${\mathrm{AdS}}_2$ geometries. Isolating the interiors of these spacetimes suggests a study of the analog of the $T\overline{T}$ deformation in quantum mechanics, which we pursue here. An equivalent description of this deformation in terms of coupling to worldline gravity is proposed, and applications to quantum-mechanical systems—including the Schwarzian theory—are studied.