We consider an extension of the minimal supersymmetric standard model (MSSM) with an added vectorlike top partner. Our aim is to revisit to what extent such an extension can raise the Higgs boson mass through radiative corrections and help ameliorate the MSSM hierarchy problem, and to specify what experimental probes at the LHC will find or exclude this possibility during the high-luminosity phase. Direct detection, precision electroweak and precision Higgs analyses are all commissioned to this end. To achieve the 125 GeV Higgs boson mass, we find that superpartner masses can be reduced by a factor of more than 3 in this scenario compared to the MSSM without the extra vectorlike top quark, and that during the high-luminosity phase of the LHC precision Higgs analysis is expected to become the most powerful experimental probe of the scenario.

We investigate a perturbative extension of the Standard Model featuring elementary pseudo-Goldstone Higgs and dark matter particles. These are two of the five Goldstone bosons parametrizing the SU(4)/Sp(4) coset space. They acquire masses, and therefore become pseudo-Goldstone bosons, due to the embedding of the Yukawa and the electroweak gauge interactions that do not preserve the full SU(4) symmetry. At the one-loop order, the top corrections dominate and align the vacuum in the direction where the Higgs is mostly a pseudo-Goldstone boson. Because of the perturbative and elementary nature of the theory, the quantum corrections are precisely calculable. The remaining pseudo-Goldstone boson is identified with the dark matter candidate because it is neutral with respect to the Standard Model and stable. By a direct comparison with the Large Hadron Collider experiments, the model is found to be phenomenologically viable. Furthermore the dark matter particle leads to the observed thermal relic density while respecting the most stringent current experimental constraints.

The decays $\omega /\varphi \to 3\pi$ are considered in the dispersive framework that is based on the isobar decomposition and subenergy unitarity. The inelastic contributions are parametrized by the power series in a suitably chosen conformal variable that properly accounts for the analytic properties of the amplitude. The Dalitz plot distributions and integrated decay widths are presented. Our results indicate that the final-state interactions may be sizable. As a further application of the formalism we also compute the electromagnetic transition form factors of $\omega /\varphi \to {\pi }^0{\gamma }^{*}$.

We investigate the $N^{*}(1535)\to N\gamma$ transition in the framework of light cone QCD sum rules. In particular, using the most general form of the interpolating current for the nucleon as well as the distribution amplitudes of the photon, we calculate two transition form factors responsible for this channel and use them to evaluate the decay width and branching ratio of the transition under consideration. The result obtained for the branching fraction is in good agreement with the experimental data.

We introduce higher-derivative Gauss-Bonnet correction terms in the gravity sector, and we relate the modified gravity theory in the bulk to the strongly coupled quantum field theory on a de Sitter boundary. We study the process of holographic thermalization by examining three nonlocal observables, the two-point function, the Wilson loop and the holographic entanglement entropy. We study the time evolution of these three observables, and we find that as the strength of the Gauss-Bonnet coupling is increased, the saturation time of the thermalization process to reach thermal equilibrium becomes shorter with the dominant effect given by the holographic entanglement entropy.

We study the finite volume/temperature correlation functions of the ($1+1$)-dimensional $\mathrm{SU}(N)$ principal chiral sigma model in the planar limit. The exact S-matrix of the sigma model is known to simplify drastically at large $N$, and this leads to trivial thermodynamic Bethe ansatz (TBA) equations. The partition function, if derived using the TBA, can be shown to be that of free particles. We show that the correlation functions and expectation values of operators at finite volume/temperature are not those of the free theory, and that the TBA does not give enough information to calculate them. Our analysis is done using the Leclair-Mussardo formula for finite-volume correlators, and knowledge of the exact infinite-volume form factors. We present analytical results for the one-point function of the energy-momentum tensor, and the two-point function of the renormalized field operator. The results for the energy-momentum tensor can be used to define a nontrivial partition function.

In this paper a ($2+1$)-dimensional model with four-fermion interactions is investigated in the case when one spatial coordinate is compactified and the space topology takes the form of an infinite cylinder, $R^1\otimes S^1$. It is supposed that the system is embedded in real three-dimensional space and that a magnetic flux $\mathrm{\Phi }$ crosses the transverse section of the cylinder. The model includes four-fermion interactions both in the fermion-antifermion (or chiral) and fermion-fermion (or superconducting) channels. We then study phase transitions that depend on the chemical potential $\mu$ and the flux $\mathrm{\Phi }$ in the leading order of the large-$N$ expansion technique, where $N$ is the number of fermion fields. It is demonstrated that for arbitrary relations between coupling constants in the chiral and superconducting channels, superconductivity appears in the system at rather high values of $\mu$ (the length $L$ of the circumference $S^1$ is fixed). Moreover, it is shown that at sufficiently small values of $\mu$ the growth of the magnetic flux $\mathrm{\Phi }$ leads to a periodical reentrance of the chiral symmetry breaking or superconducting phase, depending on the values of $\mu$ and the coupling constants.

We study $\mathcal{N}=2$ supersymmetric gauge theories on ${\mathbb{R}\mathbb{P}}^2\times {\mathbb{S}}^1$ and compute the superconformal index by using the localization technique. We consider not only the round real projective plane ${\mathbb{R}\mathbb{P}}^2$ but also the squashed real projective plane ${\mathbb{R}\mathbb{P}}_b^2$ which turns back to ${\mathbb{R}\mathbb{P}}^2$ by taking a squashing parameter $b$ as 1. In addition, we find that the result is independent of the squashing parameter $b$. We apply our new superconformal index to check the simplest case of 3D mirror symmetry, i.e., the equivalence between the $\mathcal{N}=2$ supersymmetric quantum electrodynamics (SQED) and the $XYZ$ model on ${\mathbb{R}\mathbb{P}}^2\times {\mathbb{S}}^1$. We prove it by using a mathematical formula called the $q$-binomial theorem. We also comment on the $\mathcal{N}=4$ version of mirror symmetry, mirror symmetry via generalized indices, and possibilities of generalizations from mathematical viewpoints.

New results for the fermion propagator in a laser background are presented. We show that the all orders electron propagator can be written in a compact and appealing form as a sum of sideband poles with a matrix wave function renormalization and a matrix valued mass shift. This last result is essential in the fermionic theory if we are to maintain that both the mass and its square pick up a correction only at order $e^2$. A perturbative verification of our results is carried out.

We introduce a Green’s function method for handling radiative effects on false vacuum decay. In addition to the usual thin-wall approximation, we achieve further simplification by treating the bubble wall in the planar limit. As an application, we take the $\lambda {\mathrm{\Phi }}^4$ theory, extended with $N$ additional heavier scalars, wherein we calculate analytically both the functional determinant of the quadratic fluctuations about the classical soliton configuration and the first correction to the soliton configuration itself.

The end stage of a gravitational collapse process can generically result in a black hole or a naked singularity. Here we undertake a comparative analysis of the nature of tidal forces in these backgrounds. The effect of such forces is generically exemplified by the Roche limit, which predicts the distance within which a celestial object disintegrates due to the tidal effects of a second more massive object. In this paper, using Fermi normal coordinates, we numerically compute the Roche limit for a class of nonrotating naked singularity backgrounds and compare them with known results for Schwarzschild black holes. Our analysis indicates that there might be substantially large deviations in the magnitudes of tidal forces in naked singularity backgrounds, compared to the black hole cases. If observationally established, these can prove to be an effective indicator of the nature of the singularity at a galactic center.

Computation of the renormalized stress-energy tensor is the most serious obstacle in studying the dynamical, self-consistent, semiclassical evaporation of a black hole in 4D. The difficulty arises from the delicate regularization procedure for the stress-energy tensor, combined with the fact that in practice the modes of the field need to be computed numerically. We have developed a new method for numerical implementation of the point-splitting regularization in 4D, applicable to the renormalized stress-energy tensor as well as to ${⟨{\varphi }^2⟩}_{\mathrm{ren}}$, namely the renormalized $⟨{\varphi }^2⟩$. So far we have formulated two variants of this method: $t$-splitting (aimed for stationary backgrounds) and angular splitting (for spherically symmetric backgrounds). In this paper we introduce our basic approach, and then focus on the $t$-splitting variant, which is the simplest of the two (deferring the angular-splitting variant to a forthcoming paper). We then use this variant, as a first stage, to calculate ${⟨{\varphi }^2⟩}_{\mathrm{ren}}$ in Schwarzschild spacetime, for a massless scalar field in the Boulware state. We compare our results to previous ones, obtained by a different method, and find full agreement. We discuss how this approach can be applied (using the angular-splitting variant) to analyze the dynamical self-consistent evaporation of black holes.

With positive signals from multiple direct detection experiments, it will, in principle, be possible to measure the mass and cross sections of weakly interacting massive particle (WIMP) dark matter. Recent work has shown that, with a polynomial parametrization of the WIMP speed distribution, it is possible to make an unbiased measurement of the WIMP mass, without making any astrophysical assumptions. However, direct detection experiments are not sensitive to low-speed WIMPs and, therefore, any model-independent approach will lead to a bias in the cross section. This problem can be solved with the addition of measurements of the flux of neutrinos from the Sun. This is because the flux of neutrinos produced from the annihilation of WIMPs which have been gravitationally captured in the Sun is sensitive to low-speed WIMPs. Using mock data from next-generation direct detection experiments and from the IceCube neutrino telescope, we show that the complementary information from IceCube on low-speed WIMPs breaks the degeneracy between the cross section and the speed distribution. This allows unbiased determinations of the WIMP mass and spin-independent and spin-dependent cross sections to be made, and the speed distribution to be reconstructed. We use two parametrizations of the speed distribution: binned and polynomial. While the polynomial parametrization can encompass a wider range of speed distributions, this leads to larger uncertainties in the particle physics parameters.

We develop a new approach to building cosmological models, in which small pieces of perturbed Minkowski space are joined together at reflection-symmetric boundaries in order to form a global, dynamical space-time. Each piece of this patchwork universe is described using post-Newtonian gravitational physics, with the large-scale expansion of the Universe being an emergent phenomenon. This approach to cosmology does not require any assumptions about nonlocal averaging processes. Our framework clarifies the relation between the weak-field limit of general relativity, and the cosmological solutions that result from solving Einstein’s equations with a set of symmetry assumptions. It also allows the effects of structure formation on the large-scale expansion of the Universe to be investigated without averaging anything. As an explicit example, we use this formalism to investigate the cosmological behavior of a large number of regularly arranged pointlike masses. In this case we find that the large-scale expansion is well modelled by a Friedmann-like equation that contains terms that take the form of dust, radiation, and spatial curvature. The radiation term, while small compared to the dust term, is purely a result of the nonlinearity of Einstein’s equations.

If dark matter is embedded in a nontrivial dark sector, it may annihilate and decay to lighter dark-sector states which subsequently decay to the standard model. Such scenarios—with annihilation followed by cascading dark-sector decays—can explain the apparent excess GeV gamma rays identified in the central Milky Way, while evading bounds from dark matter direct detection experiments. Each “step” in the cascade will modify the observable signatures of dark matter annihilation and decay, shifting the resulting photons and other final state particles to lower energies and broadening their spectra. We explore, in a model-independent way, the effect of multistep dark-sector cascades on the preferred regions of parameter space to explain the GeV excess. We find that the broadening effects of multistep cascades can admit final states dominated by particles that would usually produce too sharply peaked photon spectra; in general, if the cascades are hierarchical (each particle decays to substantially lighter particles), the preferred mass range for the dark matter is in all cases 20–150 GeV. Decay chains that have nearly degenerate steps, where the products are close to half the mass of the progenitor, can admit much higher dark matter masses. We map out the region of mass/cross-section parameter space where cascades (degenerate, hierarchical or a combination) can fit the signal, for a range of final states. In the current work, we study multistep cascades in the context of explaining the GeV excess, but many aspects of our results are general and can be extended to other applications.

An alternative parametrization of the particle shower longitudinal profile is presented. The accuracy of the obtained shower profile description is about 2–3% for the $0-1500\mathrm{g}/{\mathrm{cm}}^2$ atmosphere slant depths and primary H, He, $\dots \mathrm{Fe}$ nuclei in the 1 PeV–10 EeV energy range. It is shown that the shape of the shower profile depends only on the nucleon energy, whereas the maximum shower size also depends on the energy of the parental nucleus. Results are based on the corsika simulated shower profiles and are presented in comparison with the Gaisser-Hillas parametrization.

We describe a proposed experimental search for exotic spin-coupled interactions using a solid-state paramagnetic insulator. The experiment is sensitive to the net magnetization induced by the exotic interaction between the unpaired insulator electrons with a dense, nonmagnetic mass in close proximity. An existing experiment has been used to set limits on the electric dipole moment of the electron by probing the magnetization induced in a cryogenic gadolinium gallium garnet sample on application of a strong electric field. With suitable additions, including a movable source mass, this experiment can be used to explore “monopole-dipole” forces on polarized electrons with unique or unprecedented sensitivity. The solid-state, nonmagnetic construction, combined with the low-noise conditions and extremely sensitive magnetometry available at cryogenic temperatures could lead to a sensitivity over 10 orders of magnitude greater than exiting limits in the range below 1 mm.

We study the prospect of dark matter (DM) searches in the monojet channel at future $pp$ colliders with center-of-mass energies of 33, 50, and 100 TeV. We consider a class of simplified models in which a vector boson connecting DM particles to quarks is introduced. Comparing with studies in the effective field theory, the present framework gives more reasonable production rates and kinematics of the DM signatures. We estimate the sensitivities of future colliders with an integrated luminosity of $3{\mathrm{ab}}^{-1}$ to the DM-induced monojet signature and show the parameter space that can be explored. The constraints from direct and indirect DM detection experiments are compared with the future collider sensitivities. We find that the future collider detection will be much more sensitive than the indirect detection for the vector interaction and have better sensitivities than those of the direct detection by several orders of magnitude for the axial vector interaction.

The Higgs sector of the minimal supersymmetric extension of the Standard Model (MSSM) may be described with a two Higgs doublet model with properties that depend on the soft supersymmetry breaking parameters. For instance, flavor independent $CP$-violating phases associated with the gaugino masses, the squark trilinear mass parameters and the Higgsino mass parameter $\mu$ may lead to sizable $CP$-violation in the Higgs sector. For these $CP$-violating effects to affect the properties of the recently observed SM-like Higgs resonance, the nonstandard charged and neutral Higgs boson masses must be of the order of the weak scale, and both $\mu$ as well as the trilinear stop mass parameter $A_t$ must be of the order or larger than the stop mass parameters. Constraints on this possibility come from direct searches for nonstandard Higgs bosons, precision measurements on the lightest neutral Higgs properties, including its mass, and electric dipole moments. In this article, we discuss these constraints within the MSSM, trying to evaluate the possible size of the $CP$-odd component of the lightest neutral Higgs boson, and the possible experimental tests of this $CP$-violating effect at the LHC.

The gluon flux distribution of a static three quark system has been revealed at finite temperature in the pure SU(3) Yang-Mills theory. An action density operator is correlated with three Polyakov loops representing the baryonic state at temperatures near the end of the QCD plateau, $T/T_c\approx 0.8$, and another just before the deconfinement point, $T/T_c\approx 0.9$. The flux distributions at short distance separations between the quarks display an action-density profile consistent with a rounded filled $\mathrm{\Delta }$ shape iso surface. However the $\mathrm{\Delta }$ shape action iso-surface distributions are found to persist even at large interquark separations. The action density distribution in the quark plane exhibits a nonuniform pattern for all quark separations considered. This result contrasts with the Y-shaped uniform action density gluonic-flux profile obtained using the Wilson loop as a quark source operator at zero temperature. We systematically measure and compare the main aspects of the profile of the flux distribution at the two considered temperature scales for three sets of isosceles triangle quark configurations. In this paper, we present major characteristics of the gluonic profile including radii, amplitudes, and rate of change of the width of the flux distribution. These aspects show significant changes as the temperature changes from the end of the QCD plateau towards the deconfinement point. In particular, we found the flux tube is exhibiting a linear divergence at some planes of the gluonic pattern for the temperature close to the deconfinement point.