During or towards the end of inflation, the Standard Model (SM) Higgs forms a condensate with a large amplitude. Following inflation, the condensate oscillates, decaying nonperturbatively into the rest of the SM species. The resulting out-of-equilibrium dynamics converts a fraction of the energy available into gravitational waves (GWs). We study this process using classical lattice simulations in an expanding box, following the energetically dominant electroweak gauge bosons $W^{\pm }$ and $Z$. We characterize the GW spectrum as a function of the running couplings, Higgs initial amplitude, and postinflationary expansion rate. As long as the SM is decoupled from the inflationary sector, the generation of this background is universally expected, independently of the nature of inflation. Our study demonstrates the efficiency of GW emission by gauge fields undergoing parametric resonance. The initial energy of the Higgs condensate represents, however, only a tiny fraction of the inflationary energy. Consequently, the resulting background is highly suppressed, with an amplitude $h^2{\mathrm{\Omega }}_{\mathrm{GW}}^{(o)}\lesssim 10^{-29}$ today. The amplitude can be boosted to $h^2{\mathrm{\Omega }}_{\mathrm{GW}}^{(o)}\lesssim 10^{-16}$, if following inflation the universe undergoes a kination-domination stage; however, the background is shifted in this case to high frequencies $f_p\lesssim {10}^{11}\mathrm{Hz}$. In all cases the signal is out of the range of current or planned GW detectors. This background will therefore remain, most likely, as a curiosity of the SM.

One-loop Standard Model observables produced by virtual heavy Kaluza-Klein fields play a prominent role in the minimal model of universal extra dimensions. Motivated by this aspect, we integrate out all the Kaluza-Klein heavy modes coming from the Yang-Mills theory set on a spacetime with an arbitrary number, $n$, of compact extra dimensions. After fixing the gauge with respect to the Kaluza-Klein heavy gauge modes in a covariant manner, we calculate a gauge-independent effective Lagrangian expansion containing multiple Kaluza-Klein sums that entail a bad divergent behavior. We use the Epstein-zeta function to regularize and characterize discrete divergences within such multiple sums, and then we discuss the interplay between the number of extra dimensions and the degree of accuracy of effective Lagrangians to generate or not divergent terms of discrete origin. We find that nonrenormalizable terms with mass dimension $k$ are finite as long as $k>4+n$. Multiple Kaluza-Klein sums of nondecoupling logarithmic terms, not treatable by Epstein-zeta regularization, are produced by four-dimensional momentum integration. On the grounds of standard renormalization, we argue that such effects are unobservable.

The transition magnetic moment of a sterile neutrino can give rise to its conversion to an active neutrino through radiative decay or nonstandard interaction (NSI) with matter. For sterile neutrinos of keV-mass as dark matter candidates, their decay signals are actively searched for in cosmic x-ray spectra. In this work, we consider the NSI that leads to atomic ionization, which can be detected by direct dark matter experiments. It is found that this inelastic scattering process for a nonrelativistic sterile neutrino has a pronounced enhancement in the differential cross section at energy transfer about half of its mass, manifesting experimentally as peaks in the measurable energy spectra. The enhancement effects gradually smear out as the sterile neutrino becomes relativistic. Using data taken with low-threshold low-background germanium detectors, constraints on sterile neutrino mass and its transition magnetic moment are derived and compared with those from astrophysical observations.

A proton-proton collision data sample, corresponding to an integrated luminosity of $3{\mathrm{fb}}^{-1}$ collected by LHCb at $\sqrt{s}=7$ and 8 TeV, is used to reconstruct $63\pm 9$ ${\mathrm{\Omega }}_b^{-}\to {\mathrm{\Omega }}_c^0{\pi }^{-}$, ${\mathrm{\Omega }}_c^0\to p{K}^{-}{K}^{-}{\pi }^{+}$ decays. Using the ${\mathrm{\Xi }}_b^{-}\to {\mathrm{\Xi }}_c^0{\pi }^{-}$, ${\mathrm{\Xi }}_c^0\to p{K}^{-}{K}^{-}{\pi }^{+}$ decay mode for calibration, the lifetime ratio and the absolute lifetime of the ${\mathrm{\Omega }}_b^{-}$ baryon are measured to be ${\tau }_{{\mathrm{\Omega }}_b^{-}}/{\tau }_{{\mathrm{\Xi }}_b^{-}}=1.11\pm 0.16\pm 0.03$, ${\tau }_{{\mathrm{\Omega }}_b^{-}}=1.78\pm 0.26\pm 0.05\pm 0.06\mathrm{ps}$, where the uncertainties are statistical, systematic and from the calibration mode (for ${\tau }_{{\mathrm{\Omega }}_b^{-}}$ only). A measurement is also made of the mass difference, $m_{{\mathrm{\Omega }}_b^{-}}-m_{{\mathrm{\Xi }}_b^{-}}$, and the corresponding ${\mathrm{\Omega }}_b^{-}$ mass, which yields $m_{{\mathrm{\Omega }}_b^{-}}-m_{{\mathrm{\Xi }}_b^{-}}=247.4\pm 3.2\pm 0.5\mathrm{MeV}/c^2$, $m_{{\mathrm{\Omega }}_b^{-}}=6045.1\pm 3.2\pm 0.5\pm 0.6\mathrm{MeV}/c^2$. These results are consistent with previous measurements.

We consider $2+1$-dimensional off-shell $\mathcal{N}=1$ pure supergravity that is constructed from graviton, gravitino and auxiliary field. We show that the $R^2$ supersymmetric invariant and $R_{\mu \nu }^2$ supersymmetric invariant are expressed as local supersymmetric exact terms up to mass terms for the gravitino. In both cases, the mass parameter is proportional to the off-shell supersymmetric cosmological constant.

Using the chiral kinetic theory we derive the electric and chiral current densities in inhomogeneous relativistic plasma. We also derive equations for the electric and chiral chemical potentials that close the Maxwell equations in such a plasma. The analysis is done in the regimes with and without a drift of the plasma as a whole. In addition to the currents present in the homogeneous plasma (Hall current, chiral magnetic, chiral separation, and chiral electric separation effects, as well as Ohm’s current) we derive several new terms associated with inhomogeneities of the plasma. Apart from various diffusionlike terms, we find also new dissipationless terms that are independent of relaxation time. Their origin can be traced to the Berry curvature modifications of the kinetic theory.

We calculate the production of a massive vector boson by quantum fluctuations during inflation. This gives a novel dark-matter production mechanism quite distinct from misalignment or thermal production. While scalars and tensors are typically produced with a nearly scale-invariant spectrum, surprisingly the vector is produced with a power spectrum peaked at intermediate wavelengths. Thus dangerous, long-wavelength, isocurvature perturbations are suppressed. Further, at long wavelengths the vector inherits the usual adiabatic, nearly scale-invariant perturbations of the inflaton, allowing it to be a good dark-matter candidate. The final abundance can be calculated precisely from the mass and the Hubble scale of inflation, $H_I$. Saturating the dark-matter abundance we find a prediction for the mass $m\approx {10}^{-5}\mathrm{eV}\times ({10}^{14}\mathrm{GeV}/H_I{)}^4$. High-scale inflation, potentially observable in the cosmic microwave background, motivates an exciting mass range for recently proposed direct-detection experiments for hidden photon dark matter. Such experiments may be able to reconstruct the distinctive, peaked power spectrum, verifying that the dark matter was produced by quantum fluctuations during inflation and providing a direct measurement of the scale of inflation. Thus a detection would not only be the discovery of dark matter, it would also provide an unexpected probe of inflation itself.

We introduce and explore “paired” cosmological simulations. A pair consists of an A and B simulation with initial conditions related by the inversion ${\delta }_A(\mathbf{x},t_{\text{initial}})=-{\delta }_B(\mathbf{x},t_{\text{initial}})$ (underdensities substituted for overdensities and vice versa). We argue that the technique is valuable for improving our understanding of cosmic structure formation. The A and B fields are by definition equally likely draws from $\mathrm{\Lambda }\mathrm{CDM}$ initial conditions, and in the linear regime evolve identically up to the overall sign. As nonlinear evolution takes hold, a region that collapses to form a halo in simulation A will tend to expand to create a void in simulation B. Applications include (i) contrasting the growth of A-halos and B-voids to test excursion-set theories of structure formation, (ii) cross-correlating the density field of the A and B universes as a novel test for perturbation theory, and (iii) canceling error terms by averaging power spectra between the two boxes. Generalizations of the method to more elaborate field transformations are suggested.

The equations of anomalous magnetohydrodynamics describe an Abelian plasma where conduction and chiral currents are simultaneously present and constrained by the second law of thermodynamics. At high frequencies the magnetic currents play the leading role, and the spectrum is dominated by two-fluid effects. The system behaves instead as a single fluid in the low-frequency regime where the vortical currents induce potentially large hypermagnetic fields. After deriving the physical solutions of the generalized Appleton-Hartree equation, the corresponding dispersion relations are scrutinized and compared with the results valid for cold plasmas. Hypermagnetic knots and fluid vortices can be concurrently present at very low frequencies and suggest a qualitatively different dynamics of the hydromagnetic nonlinearities.

Herein we derive limits on dark matter annihilation cross section and lifetime using measurements of the AMS-02 antiproton ratio and positron fraction data. In deriving the limits, we consider the scenario of secondary particles accelerated in supernova remnants (SNRs), which has been argued to be able to reasonably account for the AMS-02 high-energy positron/antiproton fraction/ratio data. We parametrize the contribution of secondary particles accelerated in SNRs and then fit the observational data within the conventional cosmic ray propagation model by adopting the galprop code. We use the likelihood ratio test to determine the 95% confidence level upper limits of possible dark matter (DM) contribution to the antiproton/positron fractions measured by AMS-02. Under the assumption taken in this work, we find that our limits are stronger than that set by the Fermi-LAT gamma ray Pass 8 data observation on the dwarf spheroidal satellite galaxies. We show that the solar modulation (cosmic ray propagation) parameters can play a non-negligible role in modifying the constraints on dark matter annihilation cross section and lifetime for $m_{\chi }<100\mathrm{GeV}$ ($m_{\chi }>100\mathrm{GeV}$), where $m_{\chi }$ is the rest mass of dark matter particles. We also find that constrains on DM parameters from AMS-02 data would become more stringent when the solar modulation is weak. Using these results, we also put limits on the effective field theory of dark matter.

Three-dimensional Einstein gravity with a negative cosmological constant admits stationary black holes that are not necessarily spherically symmetric. We propose boundary conditions for the near-horizon region of these black holes that lead to a surprisingly simple near-horizon symmetry algebra consisting of two affine $\widehat{u}(1)$ current algebras. The symmetry algebra is essentially equivalent to the Heisenberg algebra. The associated charges give a specific example of “soft hair” on the horizon, as defined by Hawking, Perry and Strominger. We show that soft hair does not contribute to the Bekenstein-Hawking entropy of Bañados-Teitelboim-Zanelli black holes and “black flower” generalizations. From the near-horizon perspective the conformal generators at asymptotic infinity appear as composite operators, which we interpret in the spirit of black hole complementarity. Another remarkable feature of our boundary conditions is that they are singled out by requiring that the whole spectrum is compatible with regularity at the horizon, regardless of the value of the global charges like mass or angular momentum. Finally, we address black hole microstates and generalizations to cosmological horizons.

The complex pole mass of the top quark is presented at full two-loop order in the Standard Model, augmenting the known four-loop QCD contributions. The input parameters are the $\overline{\mathrm{MS}}$ Yukawa and gauge couplings, the Higgs self-coupling, and the Higgs vacuum expectation value (VEV). Here, the VEV is defined as the minimum of the full effective potential in Landau gauge, so that tadpoles vanish. This is an alternative to earlier results that instead minimize the tree-level potential, resulting in a VEV that is gauge-fixing independent but accompanied by negative powers of the Higgs self-coupling in perturbative expansions. The effects of nonzero Goldstone boson mass are eliminated by resummation. I also study the renormalization scale dependence of the calculated pole mass.

We present a novel Monte Carlo implementation of dynamic color screening via multiple exchanges of semisoft gluons as a basic QCD mechanism to understand diffractive electron-proton scattering at the HERA collider. Based on the kinematics of individual events in the standard QCD description of deep inelastic scattering at the parton level, which at low $x$ is dominantly gluon initiated, the probability is evaluated for additional exchanges of softer gluons resulting in an overall color singlet exchange leading to a forward proton and a rapidity gap as the characteristic observables for diffractive scattering. The probability depends on the impact parameter of the soft exchanges and varies with the transverse size of the hard scattering subsystem and is therefore influenced by different QCD effects. We account for matrix elements and parton shower evolution either via conventional DGLAP $\log Q^2$ evolution with collinear factorization or CCFM small $x$ evolution with $k_{\perp }$ factorization and discuss the sensitivity to the gluon density distribution in the proton and the importance of large log $x$ contributions. The overall result is, with only two model parameters which have theoretically motivated values, a satisfactory description of the observed diffractive cross section at HERA obtained in a wide kinematical range.

The two-particle short-range correlation functions in rapidity, azimuthal angle, and transverse momentum following from the decay of statistical clusters are evaluated and discussed.

The unquenching of the Polyakov-loop potential has been shown to be an important improvement for the description of the phase structure and thermodynamics of strongly interacting matter at zero quark chemical potentials with Polyakov-loop-extended chiral models. This work constitutes the first application of the quark backreaction on the Polyakov-loop potential at nonzero density. The observation is that it links the chiral and deconfinement phase transitions also at small temperatures and large quark chemical potentials. The build-up of the surface tension in the Polyakov-loop-extended quark-meson model is explored by investigating the two- and $2+1$-flavor quark-meson model and analyzing the impact of the Polyakov-loop extension. In general, the order of magnitude of the surface tension is given by the chiral phase transition. The coupling of the chiral and deconfinement transitions with the unquenched Polyakov-loop potential leads to the fact that the Polyakov loop contributes at all temperatures.

A novel technique for measuring the mass of the top quark that uses only the kinematic properties of its charged decay products is presented. Top quark pair events with final states with one or two charged leptons and hadronic jets are selected from the data set of 8 TeV proton-proton collisions, corresponding to an integrated luminosity of $19.7{\mathrm{fb}}^{-1}$. By reconstructing secondary vertices inside the selected jets and computing the invariant mass of the system formed by the secondary vertex and an isolated lepton, an observable is constructed that is sensitive to the top quark mass that is expected to be robust against the energy scale of hadronic jets. The main theoretical systematic uncertainties, concerning the modeling of the fragmentation and hadronization of $b$ quarks and the reconstruction of secondary vertices from the decays of $b$ hadrons, are studied. A top quark mass of $173.68\pm 0.20{(\mathrm{stat})}_{-0.97}^{+1.58}(\mathrm{syst})\mathrm{GeV}$ is measured. The overall systematic uncertainty is dominated by the uncertainty in the $b$ quark fragmentation and the modeling of kinematic properties of the top quark.

Monopole operators play a central role in three-dimensional supersymmetric dualities: a careful understanding of their spectrum is necessary to match chiral operators on either sides of a conjectured duality. In Chern-Simons theories ($k\ne 0$), monopole operators acquire an electric charge; thus they need to be “dressed” by chiral matter superfields to be made gauge invariant. Here we present strong evidence that “dressed” monopoles appear in $SU(N)$ chiral theories even for $k=0$ because of mixed CS terms generated along certain Coulomb branch directions. Our analysis is based on the dimensional reduction of four-dimensional dualities which, for the simplest s-confining case, allows us to easily identify the spectrum of the electric chiral operators.

In this article, we obtain a local, Becchi-Rouet-Stora-Tyutin-invariant action for QCD at finite temperature, altered from Faddeev-Popov theory due to the presence of Gribov copies. We carefully derive the horizon condition at finite temperature. Only the zero Matsubara mode is affected, and this result is consistent with the suitably modified Maggiore-Schaden shift, which takes into account temporal periodicity. The large-$N$ limit and other calculational schemes for the magnetic mass and gluon condensates and their relation to the Gribov mass are also discussed.