In this paper, we investigate an electrodynamics in which the physical modes are coupled to a Lorentz-violating background by means of a higher-derivative term. We analyze the modes associated with the dispersion relations obtained from the poles of the propagator. More specifically, we study Maxwell’s electrodynamics modified by a Lorentz-violating operator of mass dimension 6. The modification has the form $D_{\beta \alpha }{\partial }_{\sigma }{F}^{\sigma \beta }{\partial }_{\lambda }{F}^{\lambda \alpha }$; i.e., it possesses two additional derivatives coupled to a $CPT$-even tensor $D_{\beta \alpha }$ that plays the role of the fixed background. We first evaluate the propagator and obtain the dispersion relations of the theory. By doing so, we analyze some configurations of the fixed background and search for sectors where the energy is well defined and causality is assured. A brief analysis of unitarity is included for particular configurations. Afterward, we perform the same kind of analysis for a more general dimension-6 model. We conclude that the modes of both Lagrange densities are possibly plagued by physical problems, including causality and unitarity violation, and that signal propagation may become physically meaningful only in the high-momentum regime.

We investigate Planck-scale boundary conditions on Higgs quartic interactions and their $\beta$ functions in the Standard Model augmented by an additional complex scalar. We use renormalization group running at two loops, and include both theoretical and experimental constraints. We find that the boundary condition $\lambda ={\beta }_{\lambda }=0$ at the Planck scale is compatible with the current Higgs and top mass measurements, but requires additional scalars lighter than about 600 GeV.

Critical slowing down in Krylov methods for the Dirac operator presents a major obstacle to further advances in lattice field theory as it approaches the continuum solution. Here we formulate a multigrid algorithm for the Kogut-Susskind (or staggered) fermion discretization which has proven difficult relative to Wilson multigrid due to its first-order anti-Hermitian structure. The solution is to introduce a novel spectral transformation by the Kähler-Dirac spin structure prior to the Galerkin projection. We present numerical results for the two-dimensional, two-flavor Schwinger model; however, the general formalism is agnostic to dimension and is directly applicable to four-dimensional lattice QCD.

Monopolelike objects have been identified in multiple lattice studies, and there is now a significant amount of literature on their importance in phenomenology. Some analytic indications of their role, however, are still missing. The ’t Hooft-Polyakov monopoles, originally derived in the Georgi-Glashow model, are an important dynamical ingredient in theories with extended supersymmetry $\mathcal{N}=2$, 4, and help explain the issues related with electric-magnetic duality. There is no such solution in QCD-like theories without scalar fields. However, all of these theories have instantons and their finite-$T$ constituents known as instanton-dyons (or instanton-monopoles). The latter leads to semiclassical partition functions, which for $\mathcal{N}=2$, 4 theories were shown to be identical (“Poisson dual”) to the partition function for monopoles. We show how, in a pure gauge theory, the semiclassical instanton-based partition function can also be Poisson-transformed into a partition function, interpreted as the one of moving and rotating monopoles.

Drell-Yan lepton pairs produced in the process $p\overline{p}\to {\ell }^{+}{\ell }^{-}+X$ through an intermediate ${\gamma }^{*}/Z$ boson have an asymmetry in their angular distribution related to the spontaneous symmetry breaking of the electroweak force and the associated mixing of its neutral gauge bosons. The CDF and D0 experiments have measured the effective-leptonic electroweak mixing parameter ${\sin }^2{\theta }_{\mathrm{eff}}^{\mathrm{lept}}$ using electron and muon pairs selected from the full Tevatron proton-antiproton data sets collected in 2001-2011, corresponding to $9–10{\mathrm{fb}}^{-1}$ of integrated luminosity. The combination of these measurements yields the most precise result from hadron colliders, ${\sin }^2{\theta }_{\mathrm{eff}}^{\mathrm{lept}}=0.23148\pm 0.00033$. This result is consistent with, and approaches in precision, the best measurements from electron-positron colliders. The standard model inference of the on-shell electroweak mixing parameter ${\sin }^2{\theta }_W$, or equivalently the $W$-boson mass $M_W$, using the zfitter software package yields ${\sin }^2{\theta }_W=0.22324\pm 0.00033$ or equivalently, $M_W=80.367\pm 0.017\mathrm{GeV}/c^2$.

Carrying out an analysis of the constraints and their linearizations on a spacelike hypersurface, we show that topologically massive gravity has a linearization instability at the chiral gravity limit about ${\mathrm{AdS}}_3$. We also calculate the symplectic structure for all the known perturbative modes (including the log-mode) for the linearized field equations and find it to be degenerate (noninvertible); hence, these modes do not approximate exact solutions and so do not belong to the linearized phase space of the theory. Naive perturbation theory fails: the linearized field equations are necessary but not sufficient in finding viable linearized solutions. This has important consequences for both classical and possible quantum versions of the theory.

Local conditions that imply the no-hair property of black holes are completed. The conditions take the form of constraints on the geometry of the 2-dimensional crossover surface of black hole horizon. They imply also the axial symmetry without the rigidity theorem. This is the new result contained in this paper. The family of the solutions to our constraints is 2-dimensional and can be parametrized by the area and angular momentum. The constraints are induced by our assumption that the horizon is of the Petrov type D. Our result applies to all the bifurcated Killing horizons: inner or outer black hole horizons as well as cosmological horizons. Vacuum spacetimes with a given cosmological constant can be reconstructed from our solutions via Racz’s black hole holograph.

We propose a Nieh-Yan extension of $f(R)$ models in the presence of Immirzi field and the resulting theory is studied in the context of first-order formalism. We claim in our model that the ambiguities related to the Palatini approach are solved, allowing us to fully solve the theory in terms of the Immirzi field. In particular, we analyze within such a theoretical framework the propagation of gravitational waves in vacuum, and we outline that a dynamical Immirzi field could be regarded as a propagating torsion field with nontrivial and detectable effects on standard gravitational polarizations.

To understand the underlying degrees of freedom, near horizon symmetry analysis of a black hole has gain significant interest in the recent past. In this paper we generalized those analysis first by taking into account a generic null surface carrying $U(1)$ electromagnetic charge. With the appropriate boundary conditions near the surface under study, we identified the symmetry algebra among the subset of diffeomporphism and gauge generators which preserve the metric of the null surface and the form of the gauge field configuration. With the knowledge of those symmetries we further derived the algebra among the associated charges considering general Lanczos-Lovelock gravity theory and gauge theory. Importantly while computing the charges we not only considered general theory, but also used off-shell formalism which is believed to play crucial role in understanding quantum gravity. Both the nonextremal and extremal cases are addressed here.

Gravitational lensing deflects the paths of cosmic infrared background (CIB) photons, leaving a measurable imprint on CIB maps. The resulting statistical anisotropy can be used to reconstruct the matter distribution out to the redshifts of CIB sources. To this end, we generalize the cosmic microwave background (CMB) lensing quadratic estimator to any weakly non-Gaussian source field, by deriving the optimal lensing weights. We point out the additional noise and bias caused by the non-Gaussianity and the “self-lensing” of the source field. We propose methods to reduce, subtract, or model these non-Gaussianities. We show that CIB lensing should be detectable with Planck data and detectable at high significance for future CMB experiments like CCAT-Prime. The CIB thus constitutes a new source image for lensing studies, providing constraints on the amplitude of structure at intermediate redshifts between galaxies and the CMB. CIB lensing measurements will also give valuable information on the star-formation history in the Universe, constraining CIB halo models beyond the CIB power spectrum. By laying out a detailed treatment of lens reconstruction from a weakly non-Gaussian source field, this work constitutes a stepping stone toward lens reconstruction from continuum or line intensity mapping data, such as the Lyman-alpha emission, absorption, and the 21 cm radiation.

Direct searches for dark matter (DM) are continuously improving, probing down to lower and lower DM-nucleon interaction cross sections. For strongly interacting massive particle (SIMP) dark matter, however, the accessible cross section is bounded from above due to the stopping effect of the atmosphere, Earth, and detector shielding. We present a careful calculation of the SIMP signal rate, focusing on super-heavy DM ($m_{\chi }\gtrsim {10}^5\mathrm{GeV}$) for which the standard nuclear-stopping formalism is applicable, and provide code for implementing this calculation numerically. With recent results from the low-threshold CRESST 2017 surface run, we improve the maximum cross section reach of direct detection searches by a factor of about 5000, for DM masses up to $10^8\mathrm{GeV}$. A reanalysis of the longer-exposure, subsurface CDMS-I results (published in 2002) improves the previous cross section reach by 2 orders of magnitude, for masses up to $10^{15}\mathrm{GeV}$. Along with complementary constraints from SIMP capture and annihilation in the Earth and Sun, these improved limits from direct nuclear scattering searches close a number of windows in the SIMP parameter space in the mass range $10^6\mathrm{GeV}$ to $10^{13}\mathrm{GeV}$, of particular interest for heavy DM produced gravitationally at the end of inflation.

Finite size consideration of matter significantly affects transport coefficients like shear viscosity, bulk viscosity, electrical conductivity, which we have investigated here in the framework of the Polyakov–Nambu–Jona-Lasinio model. Owing to the basic quantum mechanics, a nonzero lower momentum cutoff is implemented in momentum integrations used in the expressions of constituent quark masses and transport coefficients. When the system size decreases, the values of these transport coefficients are enhanced in low temperature range. At high temperature domain, shear viscosity and electrical conductivity become independent of system sizes. Whereas bulk viscosity, which is associated with scale violating quantities of the system, faces some nontrivial size dependence in this regime. In the phenomenological direction, our microscopic estimations can also be linked with the macroscopic outcome, based on dissipative hydrodynamical simulation.

We conduct a numerical study over the constrained MSSM (CMSSM), next-to-MSSM (NMSSM) and $U(1)$ extended MSSM (UMSSM) to probe the allowed mass ranges of the charged Higgs boson and its dominant decay patterns, which might come into prominence in the near future collider experiments. We present results obtained from a limited scan for CMSSM as a basis and compare its predictions with the extended models. We observe within our data that a wide mass range is allowed as $0.5(1)\lesssim m_{H^{\pm }}\lesssim 17\mathrm{TeV}$ in UMSSM (NMSSM). We find that the dominant decay channel is mostly $H^{\pm }\to tb$ such that $\mathrm{BR}(H^{\pm }\to tb)\sim 80\%$. While this mode remains dominant over the whole allowed parameter space of CMSSM, we realize some special domains in the NMSSM and UMSSM, in which $\mathrm{BR}(H^{\pm }\to tb)\lesssim 10\%$. In this context, the decay patterns of the charged Higgs can play a significant role to distinguish among the SUSY models. In addition to the $tb$ decay mode, we find that the narrow mass scale in CMSSM allows only the decay modes for the charged Higgs boson to $\tau \nu$ ($\sim 16\%$), and their supersymmetric partners $\tilde{\tau }\tilde{\nu }$ ($\sim 13\%$). On the other hand, it is possible to realize the mode in NMSSM and UMSSM in which the charged Higgs boson decays into a chargino and neutralino pair up to about 25%. This decay mode requires nonuniversal boundary conditions within the MSSM framework to be available, since CMSSM yields $\mathrm{BR}(H^{\pm }\to {\tilde{\chi }}_1^0{\tilde{\chi }}_1^{\pm })\lesssim 1\%$. It can also be probed in the near future collider experiments through the missing energy and $CP$-violation measurements. Moreover, the chargino mass is realized as $m_{{\tilde{\chi }}_1^{\pm }}\gtrsim 1\mathrm{TeV}$ in NMSSM and UMSSM, and these solutions will be likely tested soon in collider experiments through the chargino-neutralino production. Focusing on the chargino-neutralino decay patterns, we also present tables which list the possible ranges for the charged Higgs production and decay modes.

We analyze two types of Hermitian matrix models with asymmetric solutions. One type breaks the symmetry explicitly with an asymmetric quartic potential. We give the phase diagram of this model with two different phase transitions between the one cut and two cut solutions. The second type, describing real scalar field theory on fuzzy spaces, breaks the symmetry spontaneously with multitrace terms. We present two methods to study this model, one direct and one using a connection with the first type of models. We analyze the model for the fuzzy sphere and obtain a phase diagram with the location of the triple point in good agreement with the most recent numerical simulations.

We investigate the gravitational waves and their properties in various modified teleparallel theories, such as $f(T)$, $f(T,B)$, and $f(T,T_G)$ gravities. We perform the perturbation analysis both around a Minkowski background and in the case where a cosmological constant is present, and for clarity we use both the metric and the tetrad languages. For $f(T)$ gravity we verify the result that no further polarization modes comparing to general relativity are present at first-order perturbation level, and we show that in order to see extra modes one should look at third-order perturbations. For nontrivial $f(T,B)$ gravity, by examining the geodesic deviation equations, we show that extra polarization models, namely the longitudinal and breathing modes, do appear at first-order perturbation level, and the reason for this behavior is the fact that although the first-order perturbation does not have any effect on $T$, it does affect the boundary term $B$. Finally, for $f(T,T_G)$ gravity we show that at first-order perturbations the gravitational waves exhibit the same behavior as those of $f(T)$ gravity. Since different modified teleparallel theories exhibit different gravitational wave properties, the advancing gravitational-wave astronomy would help to alleviate the degeneracy not only between curvature and torsional modified gravity but also between different subclasses of modified teleparallel gravities.

Using the analogy between acoustic perturbations in an ideal fluid and the description of a Klein-Gordon scalar field in a curved spacetime, we study the quasinormal modes of a quantum system: the rotating Bose-Einstein condensate. To compute quasinormal frequencies, we use two different numerical techniques, namely the direct integration and the continued-fraction methods. We study in detail the ergoregion instability of this linearly perturbed system, comparing the results with different setup configurations.

We give a local description of the Euclidean regime $(M,\mathit{g},\mathit{u})$ of Lorentzian spacetimes $(M,\mathit{g})$ based on timelike geodesics $\mathit{u}$ passing through an arbitrary event $p_0\in M$. We show that, to leading order, the Euclidean Einstein-Hilbert action $I_E$ is proportional to the Einstein tensor $\mathit{G}[\mathit{g}](\mathit{u},\mathit{u})$. The positivity of $I_E$ follows if $\mathit{G}[\mathit{g}](\mathit{u},\mathit{u})>0$ holds. We suggest an interpretation of this result in terms of the amplitude $\mathcal{A}[{\mathrm{\Sigma }}_0]=\exp [-I_E]$ for a single spacelike hypersurface ${\mathrm{\Sigma }}_0\in I^{+}(p_0)$ to emerge at a constant geodesic distance ${\lambda }_0$ from $p_0$. Implications for classical and quantum gravity are discussed.

The canonical tensor model (CTM) is a tensor model in Hamilton formalism and is studied as a model for gravity in both classical and quantum frameworks. Its dynamical variables are a canonical conjugate pair of real symmetric three-index tensors, and a question in this model was how to extract spacetime pictures from the tensors. We give such an extraction procedure by using two techniques widely known in data analysis. One is the tensor-rank (or $CP$ etc.) decomposition, which is a certain generalization of the singular value decomposition of a matrix and decomposes a tensor into a number of vectors. By regarding the vectors as points forming a space, topological properties are extracted by using the other data analysis technique called persistent homology, and geometries by virtual diffusion processes over points. Thus, time evolutions of the tensors in the CTM can be interpreted as topological and geometric evolutions of spaces. We have performed some initial investigations of the classical equation of motion of the CTM in terms of these techniques for a homogeneous fuzzy circle and homogeneous two- and three-dimensional fuzzy spheres as spaces, and have obtained agreement with the general relativistic system obtained previously in a formal continuum limit of the CTM. It is also demonstrated by some concrete examples that the procedure is general for any dimensions and topologies, showing the generality of the CTM.

The $\mathrm{\Lambda }\mathrm{CDM}$ model is a remarkably successful model which is consistent with the observations of cosmic microwave background radiation (CMB), baryon acoustic oscillation (BAO), and the large scale structure of the Universe. However, the discrepancy in the value of $H_0$ between the local observations and PLANCK observation of CMB was recently pointed out. One of the ways to ease the discrepancy is to introduce phantom dark energy instead of the cosmological constant. However, phantom dark energy often suffers from instabilities. We will investigate the general solution to overcome the difficulty of phantom dark energy and construct some particular models which have a phantom crossing and can be consistent with the observations.