We derive the transport equations of quark-gluon plasma in the quasilinear approximation. The equations are either of the Balescu-Lenard or Fokker-Planck form. The plasma’s dynamics is assumed to be governed by longitudinal chromoelectric fields. The isotropic plasma, which is stable, and the two-stream system, which is unstable, are considered in detail. A process of equilibration is briefly discussed in both cases. The peaks of the two-stream distribution are shown to rapidly dissolve in time.

The Newtonian regime of a recent nonlocal extension of general relativity is investigated. Nonlocality is introduced via a scalar “constitutive” kernel in a special case of the translational gauge theory of gravitation, namely, the teleparallel equivalent of general relativity. In this theory, the nonlocal aspect of gravity simulates dark matter. A nonlocal and nonlinear generalization of Poisson’s equation of Newtonian gravitation is presented. The implications of nonlocality for the gravitational physics in the solar system are briefly studied.

We propose to apply Ramsey’s method of separated oscillating fields to the spectroscopy of the quantum states in the gravity potential above a horizontal mirror. This method allows a precise measurement of quantum mechanical phaseshifts of a Schrödinger wave packet bouncing off a hard surface in the gravitational field of the Earth. Measurements with ultracold neutrons will offer a sensitivity to Newton’s law or hypothetical short-ranged interactions, which is about 21 orders of magnitude below the energy scale of electromagnetism.

We construct the $SU(5)$ and $SO(10)$ models from F-theory. Turning on the $U(1)$ fluxes, we can break the $SU(5)$ gauge symmetry down to the standard model (SM) gauge symmetry, and break the $SO(10)$ gauge symmetry down to the $SU(3{)}_C\times SU(2{)}_L\times SU(2{)}_R\times U(1{)}_{B-L}$ gauge symmetry. In particular, all the SM fermion Yukawa couplings preserve the enhanced $U(1{)}_a\times U(1{)}_b$ gauge or global symmetries at the triple intersections of the SM fermion and Higgs curves. And the SM fermion masses and mixings can be generated in the presence of background fluxes. In our models, the doublet-triplet splitting problem can be solved naturally. The additional vectorlike particles can obtain heavy masses via the instanton effects or Higgs mechanism and then decouple at the high scale. The SM gauge couplings at the string scale, which are split due to the $U(1)$ flux effects, can be explained by considering heavy threshold corrections from the extra vectorlike particles. Moreover, in the $SU(5)$ model, we have the Yukawa coupling unification for the bottom quark and tau lepton. In the $SO(10)$ models, we have the Yukawa coupling unification for the top and bottom quarks, and the Yukawa coupling unification for the tau lepton and tau neutrino.

Hamiltonian perturbation theory is used to analyze the stability of $f(R)$ models. The Hamiltonian equations for the metric and its momentum conjugate are written for the $f(R)$ Lagrangian in the presence of perfect fluid matter. The perturbations examined are perpendicular to $R$. As perturbations are added to the metric and momentum conjugate to the induced metric instabilities are found, depending on the form of $f(R)$. Thus the examination of these instabilities is a way to rule out certain $f(R)$ models.

The existence of large-scale magnetic fields in the universe has led to the observation that if gravitational waves propagating in a cosmological environment encounter even a small magnetic field then electromagnetic radiation is produced. To study this phenomenon in more detail we take it out of the cosmological context and at the same time simplify the gravitational radiation to impulsive waves. Specifically, to illustrate our findings, we describe the following three physical situations: (1) a cylindrical impulsive gravitational wave propagating into a universe with a magnetic field, (2) an axially symmetric impulsive gravitational wave propagating into a universe with an electric field and (3) a “spherical” impulsive gravitational wave propagating into a universe with a small magnetic field. In cases (1) and (3) electromagnetic radiation is produced behind the gravitational wave. In case (2) no electromagnetic radiation appears after the wave unless a current is established behind the wave breaking the Maxwell vacuum. In all three cases the presence of the magnetic or electric fields results in a modification of the amplitude of the incoming gravitational wave which is explicitly calculated using the Einstein–Maxwell vacuum field equations.

We present a measurement of an angular antispring effect caused by radiation pressure in an optical cavity with a mirror of 20 mg suspended by a silica fiber of $10\mu \mathrm{m}$ in diameter. The antispring effect occurred since the torque on the suspended mirror is increased with the higher radiation pressure force, pushing the system towards instability. We measured shifts of the rotational resonant frequencies of the suspended mirror from 2.0 Hz to 1.0 Hz with the increased circulating power. It is verified that the result agrees with the theoretical curve to show the antispring effect. The result proves that it will be possible to make a reliable control system model of the radiation pressure effect for the second generation of the gravitational wave detectors.

We consider a ($1+1$)-dimensional model of general relativity that is based on a geometric theory of gravity due to Nordström. We show that the theory is formally equivalent to scalar field theory in flat spacetime, and we exploit this equivalence to solve the initial value problem for the system for the case of point particle sources. We illustrate our results by obtaining several example solutions to the model.

We perform a study of the gravitating electrostatic spherically symmetric (G-ESS) solutions of Einstein field equations minimally coupled to generalized nonlinear Abelian gauge models in three space dimensions. These models are defined by Lagrangian densities which are general functions of the gauge field invariants, restricted by some physical conditions of admissibility. They include the class of nonlinear electrodynamics supporting electrostatic spherically symmetric (ESS) nontopological soliton solutions in absence of gravity. We establish that the qualitative structure of the G-ESS solutions of admissible models is fully characterized by the asymptotic and central-field behaviors of their ESS solutions in flat space (or, equivalently, by the behavior of the Lagrangian densities in vacuum and on the point of the boundary of their domain of definition, where the second gauge invariant vanishes). The structure of these G-ESS configurations for admissible models supporting divergent-energy ESS solutions in flat space is qualitatively the same as in the Reissner-Nordström case. In contrast, the G-ESS configurations of the models supporting finite-energy ESS solutions in flat space exhibit new qualitative features, which are discussed in terms of the Arnowitt-Deser-Misner mass, the charge, and the soliton energy. Most of the results concerning well-known models, such as the electrodynamics of Maxwell, Born-Infeld, and the Euler-Heisenberg effective Lagrangian of QED, minimally coupled to gravitation, are shown to be corollaries of general statements of this analysis.

At the level of heuristic effective dynamics, we investigate the cosmological inflation with holonomy corrections of loop quantum cosmology in the $k=0$ Friedmann-Robertson-Walker model with a single inflaton field subject to a simple potential. In the symmetric bouncing scenario of loop quantum cosmology, the condition for occurrence of the quantum bounce naturally and uniquely fixes the initial conditions at the bouncing epoch. Around the quantum bounce, the Universe undergoes a short superinflationary phase, which drives the inflaton field to its potential hill and thus sets the proper initial conditions for the standard slow-roll inflation. Between the superinflation and the standard inflation, there is a noninflationary phase, which violates the slow-roll condition. The violation of slow roll is expected to give some suppression on the low angular power spectrum of the cosmic microwave background and different orders of holonomy corrections shall yield different suppressions.

A quintessence scalar field or cosmon interacting with neutrinos can have important effects on cosmological structure formation. Within growing neutrino models the coupling becomes effective only in recent times, when neutrinos become nonrelativistic, stopping the evolution of the cosmon. This can explain why dark energy dominates the Universe only in a rather recent epoch by relating the present dark energy density to the small mass of neutrinos. Such models predict the presence of stable neutrino lumps at supercluster scales ($\sim 200\mathrm{Mpc}$ and bigger), caused by an attractive force between neutrinos which is stronger than gravity and mediated by the cosmon. We present a method to follow the initial nonlinear formation of neutrino lumps in physical space, by integrating numerically on a 3D grid nonlinear evolution equations, until virialization naturally occurs. As a first application, we show results for cosmologies with final large neutrino average mass $\sim 2\mathrm{eV}$: in this case, neutrino lumps indeed form and mimic very large cold dark matter structures, with a typical gravitational potential ${10}^{-5}$ for a lump size $\sim 10\mathrm{Mpc}$, and reaching larger values for lumps of about 200 Mpc. A rough estimate of the cosmological gravitational potential at small $k$ in the nonlinear regime, ${\Phi }_{\nu }={10}^{-6}(k/k_0{)}^{-2}$, $1.2\times {10}^{-2}\mathrm{h}/\mathrm{Mpc}<k_0<7.8\times {10}^{-2}\mathrm{h}/\mathrm{Mpc}$, turns out to be many orders of magnitude smaller than an extrapolation of the linear evolution of density fluctuations. The size of the neutrino-induced gravitational potential could modify the spectrum of CMB anisotropies for small angular momenta.

The present operation of the ground-based network of gravitational-wave laser interferometers in enhanced configuration and the beginning of the construction of second-generation (or advanced) interferometers with planned observation runs beginning by 2015 bring the search for gravitational waves into a regime where detection is highly plausible. The development of techniques that allow us to discriminate a signal of astrophysical origin from instrumental artefacts in the interferometer data and to extract the full range of information are therefore some of the primary goals of the current work. Here we report the details of a Bayesian approach to the problem of inference for gravitational wave observations using a network (containing an arbitrary number) of instruments, for the computation of the Bayes factor between two hypotheses and the evaluation of the marginalized posterior density functions of the unknown model parameters. The numerical algorithm to tackle the notoriously difficult problem of the evaluation of large multidimensional integrals is based on a technique known as nested sampling, which provides an attractive (and possibly superior) alternative to more traditional Markov-chain Monte Carlo methods. We discuss the details of the implementation of this algorithm and its performance against a Gaussian model of the background noise, considering the specific case of the signal produced by the in-spiral of binary systems of black holes and/or neutron stars, although the method is completely general and can be applied to other classes of sources. We also demonstrate the utility of this approach by introducing a new coherence test to distinguish between the presence of a coherent signal of astrophysical origin in the data of multiple instruments and the presence of incoherent accidental artefacts, and the effects on the estimation of the source parameters as a function of the number of instruments in the network.

We study the octet $SS-PP$ correlator within resonance chiral theory up to the one-loop level, i.e., up to next-to-leading order in the $1/N_C$ expansion. We require that our correlator follows the power behavior prescribed by the operator product expansion at high Euclidean momentum. Nevertheless, we will not make use of short-distance constraints from other observables. Likewise, the high energy behavior will be demanded for the whole correlator, not for individual absorptive channels. The amplitude is progressively improved by considering more and more complicated operators in the hadronic Lagrangian. Matching the resonance chiral theory result with chiral perturbation theory at low energies produces the estimates $L_8(\mu {)}^{SU(3)}=(1.0\pm 0.4)\times {10}^{-3}$ and $C_{38}(\mu {)}^{SU(3)}=(8\pm 5)\times {10}^{-6}$ for $\mu =770\mathrm{MeV}$. The effect of alternative renormalization schemes is also discussed in the article.

Using the latest quark Sivers functions extracted from the global analysis of available data on single transverse spin asymmetry (SSA), we calculate the SSA of Drell-Yan inclusive production of lepton pairs of invariant mass $Q$ at both $4<Q<9\mathrm{GeV}$ and $Q\sim M_Z$ in $p^{\uparrow }p$ collisions at Relativistic Heavy Ion Collider energies. We find that the features of the asymmetry $A_N$ for $Q\sim M_Z$ are significantly different from that when $4<Q<9\mathrm{GeV}$. The $A_N$ near $Z^0$ pole is positive and sizable in the central rapidity region, while the $A_N$ at low $Q$ is negative and only sizable in the forward rapidity region. We show that the size of $A_N$ is sufficiently large for a wide range of $Q$ around the $Z^0$ pole, and even with the lepton pair’s invariant mass integrated from $Q=70\mathrm{GeV}$ to 110 GeV, the $A_N$ is still close to 10% for the central and near forward rapidity region. We argue that the SSAs of Drell-Yan inclusive dilepton production at low $Q$, and that near the $Z^0$ pole, provide complementary information for testing the time-reversal modified universality (the sign change) of the Sivers functions.

The meson masses and mixing angles have been calculated for the scalar and pseudoscalar sector in the framework of the generalized $2+1$ flavor Polyakov loop augmented quark meson linear sigma model. We have given the results for two different forms of the effective Polyakov loop potential. The comparison of results with the existing calculations in the bare $2+1$ quark meson linear sigma model, shows that the restoration of chiral symmetry becomes sharper due to the influence of the Polyakov loop potential. We find that inclusion of the Polyakov loop in the quark meson linear sigma model together with the presence of axial anomaly, triggers an early and significant melting of the strange condensate. We have examined how the inclusion of the Polyakov loop qualitatively and quantitatively affects the convergence in the masses of the chiral partners in pseudoscalar ($\pi$, $\eta$, ${\eta }^{\prime }$, $K$) and scalar ($\sigma$, $a_0$, $f_0$, $\kappa$) meson nonets as the temperature is varied on the reduced temperature scale. The role of $U_A(1)$ anomaly in determining the isoscalar masses and mixing angles for the pseudoscalar ($\eta$ and ${\eta }^{\prime }$) and scalar ($\sigma$ and $f_0$) meson complex, has also been investigated in the Polyakov loop augmented quark meson linear sigma model. The interplay of chiral symmetry restoration effects and the setting up of $U_A(1)$ restoration trend has been discussed and analyzed in the framework of the presented model calculations.

Crucial information on the coupling of the Higgs boson to bottom quarks is expected from Higgs production in association with a forward tagging jet at a future high-energy lepton-proton collider. In order to control the theoretical uncertainties of the signal process, the impact of radiative corrections has to be quantified. We present the full next-to-leading-order QCD corrections to $e^{-}p\to e^{-}jH$ and $e^{-}p\to {\nu }_{e}jH$ in the form of a flexible Monte-Carlo program allowing for the calculation of cross sections and kinematic distributions within experimentally feasible selection cuts. QCD corrections are found to be very small for cross sections, while the shape distortion of distributions can be as large as 20%. Residual scale uncertainties at next-to-leading order are at the permille level.

The equilibrium size and temperature limits of thermally and chemically equilibrated $e^{+}{e}^{-}\gamma$ plasma drops are investigated at a given energy content. For a plasma to be equilibrated it must be opaque to electron and photon interactions. The opaqueness condition is determined by comparing plasma size with the mean free electron and photon paths. We calculate those paths using thermal Lorentz-invariant reaction rates for pair production and electron (positron) and photon scattering. The range of the corresponding plasma temperature and size is evaluated numerically. Considering the energy and size we find that the opaque and equilibrated plasma drop may be experimentally attainable.

Transport coefficients can be obtained from two-point correlators using the Kubo formulas. It has been shown that the full leading order result for electrical conductivity and (QCD) shear viscosity is contained in the resummed two-point function that is obtained from the three-loop three-particle irreducible resummed effective action. The theory produces all leading order contributions without the necessity for power counting, and in this sense it provides a natural framework for the calculation. In this article we study the four-loop four-particle irreducible effective action for a scalar theory with cubic and quartic interactions, with a nonvanishing field expectation value. We obtain a set of integral equations that determine the resummed two-point vertex function. A next-to-leading order contribution to the viscosity could be obtained from this set of coupled equations.

We compute trivariate probability distributions in the landscape, scanning simultaneously over the cosmological constant, the primordial density contrast, and spatial curvature. We consider two different measures for regulating the divergences of eternal inflation, and three different models for observers. In one model, observers are assumed to arise in proportion to the entropy produced by stars; in the others, they arise at a fixed time (5 or $10\times {10}^9$ years) after star formation. The star formation rate, which underlies all our observer models, depends sensitively on the three scanning parameters. We employ a recently developed model of star formation in the multiverse, a considerable refinement over previous treatments of the astrophysical and cosmological properties of different pocket universes. For each combination of observer model and measure, we display all single and bivariate probability distributions, both with the remaining parameter(s) held fixed and marginalized. Our results depend only weakly on the observer model but more strongly on the measure. Using the causal diamond measure, the observed parameter values (or bounds) lie within the central $2\sigma$ of nearly all probability distributions we compute, and always within $3\sigma$. This success is encouraging and rather nontrivial, considering the large size and dimension of the parameter space. The causal patch measure gives similar results as long as curvature is negligible. If curvature dominates, the causal patch leads to a novel runaway: it prefers a negative value of the cosmological constant, with the smallest magnitude available in the landscape.

Small neutrino masses and their large mixing angles can be generated at the TeV scale by augmenting the standard model with an additional generation-dependent, anomaly-free $U(1{)}_{\nu }$ symmetry, in the presence of three right-handed neutrinos. The $Z^{\prime }$ gauge boson associated with the breaking of the $U(1{)}_{\nu }$ symmetry can be produced at the LHC. The flavorful nature of the $Z^{\prime }$ can be established by measuring its nonuniversal couplings to the charged leptons as determined by the lepton’s $U(1{)}_{\nu }$ charges, which also govern the neutrino flavor structure. While the LHC has the potential of discovering the $Z^{\prime }$ up to $M_{Z^{\prime }}=4.5\mathrm{TeV}$ with $100{\mathrm{fb}}^{-1}$ data at the center of mass energy $\sqrt{s}=14\mathrm{TeV}$, to establish the flavorful nature of the $Z^{\prime }$ requires much higher integrated luminosity. For our benchmark parameters that are consistent with neutrino oscillation data, at $\sqrt{s}=14\mathrm{TeV}$, a $5\sigma$ distinction between the dielectron and dimuon channels for $M_{Z^{\prime }}=3\mathrm{TeV}$ requires $500{\mathrm{fb}}^{-1}$ of data. We find that the forward backward asymmetry distributions can also be useful in distinguishing the dielectron and dimuon channels in the low invariant mass and transverse momentum regions.