In this work, the quark-hadron phase transition in a chameleon Brans-Dicke model of brane world cosmology within an effective model of QCD is investigated. Whereas, in the chameleon Brans-Dicke model of brane world cosmology, the Friedmann equation and conservation of density energy are modified, resulting in an increased expansion in the early Universe. These have important effects on quark-hadron phase transitions. We investigate the evolution of the physical quantities relevant to quantitative descriptions of the early times, namely, the energy density, $\rho$, temperature, $T$, and the scale factor, $a$, before, during, and after the phase transition. We do this for smooth crossover formalism in which lattice QCD data is used for obtaining the matter equation of state and first order phase transition formalism. Our analyses show that the quark-hadron phase transition has occurred at approximately one nanosecond after the big bang and the general behavior of temperature is similar in both of two approaches.

We study the hadron-quark phase transition at finite temperature in the interior of protoneutron stars, combining the Dyson-Schwinger model for quark matter with the Brueckner-Hartree-Fock approach for hadronic matter. We discuss the dependence of the results on different nuclear three-body forces and on details of the quark model. A maximum mass exceeding two solar masses can only be obtained with a strong three-body force and suitable parameter values in the Dyson-Schwinger model. With a hybrid configuration, the maximum mass of protoneutron stars is larger than that of cold neutron stars, such that a delayed collapse might be possible in principle.

The dark matter halo of the Milky Way is expected to contain an abundance of smaller subhalos. These subhalos can be dense and produce potentially observable fluxes of gamma rays. In this paper, we search for dark matter subhalo candidates among the sources in the Fermi-LAT second source catalog which are not currently identified or associated with counterparts at other wavelengths. Of the nine high-significance, high-latitude ($|b|>60°$), nonvariable, unidentified sources contained in this catalog, only one or two are compatible with the spectrum of a dark matter particle heavier than approximately 50–100 GeV. The majority of these nine sources, however, feature a spectrum that is compatible with that predicted from a lighter ($\sim 5–40\mathrm{GeV}$) dark matter particle. This population is consistent with the number of observable subhalos predicted for a dark matter candidate in this mass range and with an annihilation cross section of a simple thermal relic ($\sigma v\sim 3\times {10}^{-26}{\mathrm{cm}}^3/\mathrm{s}$). Observations in the direction of these sources at other wavelengths will be necessary to either reveal their astrophysical nature (as blazars or other active galactic nuclei, for example), or to further support the possibility that they are dark matter subhalos by failing to detect any non-gamma-ray counterpart.

In the past decade or so observations of supernovae, large scale structures, and the cosmic microwave background have confirmed the presence of what is called dark energy—the cause of the accelerating expansion of the Universe. Its density has also been measured as well as the value of other cosmological parameters according to the concordance $\Lambda \mathrm{CDM}$ model with few percent uncertainties. The next generation of surveys should allow to constrain this model with better precision or to distinguish between a $\Lambda \mathrm{CDM}$ and alternative models such as modified gravity and (interacting)-quintessence models. In this work we parametrize both the homogeneous and anisotropic components of matter density in the context of interacting dark energy models with the goal of discriminating between $f(R)$ modified gravity and its generalizations, and interacting dark energy models, for which we also propose a phenomenological description of energy-momentum conservation equations inspired by particle physics. It is based on the fact that the simplest interactions between particles/fields are elastic scattering and decay. The parametrization of the growth rate proposed here is nonetheless general and can be used to constrain other interactions. As an example of applications, we present an order of magnitude estimation of the accuracy of the measurement of these parameters using Euclid and Planck surveys data, and leave a better estimation to a dedicated work.

There are two main approaches to nonequilibrium statistical mechanics: one using stochastic processes and the other using dynamical systems. To model the dynamics during inflation, one usually adopts a stochastic description, which is known to suffer from serious conceptual problems. To overcome the problems and/or to gain more insight, we develop a dynamical systems approach. A key assumption which goes into analysis is the chaotic hypothesis, which is a natural generalization of the ergodic hypothesis to non-Hamiltonian systems. The unfamiliar feature for gravitational systems is that the local phase-space trajectories can either reproduce or escape due to the presence of cosmological and black hole horizons. We argue that the effect of horizons can be studied using dynamical systems and apply the so-called thermodynamic formalism to derive the equilibrium (or Sinai-Ruelle-Bowen) measure given by a variational principle. We show that the only physical measure is not the Liouville measure (i.e. no entropy problem), but the equilibrium measure (i.e. no measure problem) defined over local trajectories (i.e. no problem of observables) and supported on only infinite trajectories (i.e. no problem of initial conditions). Phenomenological aspects of the fluctuation theorem are discussed.

The abundance of primordial black holes is currently significantly constrained in a wide range of masses. The weakest limits are established for the small mass objects where the small intensity of the associated physical phenomenon provides a challenge for current experiments. We used gamma-ray bursts with known redshifts detected by the Fermi Gamma-ray Burst Monitor (GBM) to search for the femtolensing effects caused by compact objects. The lack of femtolensing detection in the GBM data provides new evidence that primordial black holes in the mass range ${10}^{17}–{10}^{20}\mathrm{g}$ do not constitute a major fraction of dark matter.

The quantum fluctuations of an “accelerated” vacuum state, that is, vacuum fluctuations in the presence of a constant electromagnetic field, can be described by the temperature $T_{\mathrm{M}}$. Considering $T_{\mathrm{M}}$ for the gyromagnetic factor $g=1$ we show that $T_{\mathrm{M}}(g=1)=T_{\mathrm{U}}$, where $T_{\mathrm{U}}$ is the Unruh temperature experienced by an accelerated observer. We conjecture that both particle production and nonlinear field effects inherent in the Unruh accelerated observer case are described by the case $g=1$ QED of strong fields. We present rates of particle production for $g=0$, 1, 2 and show that the case $g=1$ is experimentally distinguishable from $g=0$, 2. Therefore, either accelerated observers are distinguishable from accelerated vacuum or there is unexpected modification of the theoretical framework.

In a recent paper, a minimal supersymmetric (SUSY) $SO(10)\times S_4$ based unified model of flavor for quarks and leptons was proposed with two $\mathbf{10}$ and one $\mathbf{126}$ contributing to fermion masses. An important aspect of this model is that Yukawa couplings emerge dynamically from minimization of the flavon potential, thereby reducing the number of parameters considerably. We make a detailed numerical analysis of this model for fermion mixings including SUSY threshold effects at the TeV scale and type-I corrections to a type-II dominant seesaw for neutrino masses. This is a single-step breaking model with SUSY $SO(10)$ broken at the grand unified theory scale of $2\times {10}^{16}\mathrm{GeV}$ to the minimal supersymmetric standard model. The minimal model has only 11 parameters, and therefore, the charged fermion fits predict the masses (up to an overall scale) and mixings in the neutrino sector. We present correlations for the different predictions in the neutrino mixing parameters. The recent experimental “large” ${\theta }_{13}$ value of $\sim 9°$ can be obtained by a simple extension of the minimal model. We also find that proton decay mode $p\to K^{+}{\overline{\nu }}_{\mu }$ has a partial lifetime of $\sim {10}^{34}\mathrm{yrs}$, which is within reach of the next round of planned proton decay searches. The successful fit for fermion masses requires the Higgs mass to be below 129 GeV in this model. If the Higgs mass lies between 120 and 128 GeV, as suggested by the recent LHC data, we find a lower limit on the light stop mass of 755 (211) GeV for $\mu >0(<0)$.

We studied the dimension-6 leptonic anomalous gauge couplings in the formulation of linearly realized gauge symmetry effective Lagrangian and investigated the constraints on these anomalous couplings from the existing experimental data, including LEP2 and $W/Z$ boson decay. Some loose bounds of $O(0.1–10){\mathrm{TeV}}^{-2}$ on four relevant anomalous couplings are given by the $Z$ factories. We studied the sensitivity of testing the leptonic anomalous couplings via the process $e^{+}{e}^{-}\to W^{+}{W}^{-}$ at future $e^{+}{e}^{-}$ linear colliders. We discussed different sensitivities to anomalous couplings at polarized and unpolarized $e^{+}{e}^{-}$ colliders, respectively, with 500 GeV and 1 TeV collision energy. Our results show that the 500 GeV International Linear Collider (ILC) can provide a test of the anomalous couplings, with the same relative uncertainty of cross section measurement, of $O({10}^{-3}–{10}^{-2}){\mathrm{TeV}}^{-2}$, and a 1 TeV ILC can test the anomalous couplings of $O({10}^{-4}–{10}^{-3}){\mathrm{TeV}}^{-2}$.

In the current work, spectroscopy and the possibility of observation at the LHC of tetraquarks composed of four heavy quarks are discussed. The tetraquarks concerned are $T_{4c}=[cc][\overline{c}\overline{c}]$, $T_{4b}=[bb][\overline{b}\overline{b}]$, and $T_{2[bc]}=[bc][\overline{b}\overline{c]}$. By solving the nonrelativistic Schrödinger equation, masses of these states are found with the hyperfine splitting that is accounted for. It is shown that masses of tensor tetraquarks $T_{4c}(2^{++})$ and $T_{2[bc]}(2^{++})$ are high enough to observe these states as peaks in the invariant mass distributions of heavy quarkonia pairs in $pp\to T_{4c}+X\to 2J/\psi +X$, $pp\to T_{2[bc]}+X\to 2B_c+X$ and $pp\to T_{2[bc]}+X\to J/\psi {\rm Y}(1S)+X$ channels, while $T_{4b}$ is under the threshold of decay into a vector bottomonia pair.

Masses of the pseudoscalar ($J^{\mathrm{PC}}=0^{-+}$) charmonium and bottomonium hybrids are determined using QCD Laplace sum-rules. The effects of the dimension-six gluon condensate are included in our analysis and result in a stable sum-rule analysis, whereas previous studies of these states were unable to optimize mass predictions. The pseudoscalar charmonium hybrid is predicted to have a mass of approximately 3.8 GeV and the corresponding bottomonium prediction is 10.6 GeV. Calculating the full correlation function, rather than only the imaginary part, is shown to be necessary for accurate formulation of the sum-rules. The charmonium hybrid mass prediction is discussed within the context of the $XYZ$ resonances.

We show that there is an infinite number of $U(1)$ symmetries like Peccei-Quinn symmetry in the 3-3-1 model with minimal scalar sector—two scalar triplets. Moreover, all of them are completely broken due to the model’s scalars by themselves (notice that these scalars as known to have been often used to break the gauge symmetry and to generate the masses for the model’s particles). There is not any residual Peccei-Quinn symmetry. Because of the minimal scalar content, there are some quarks that are massless at tree level, but they can get consistent mass contributions at one loop due to this fact. Interestingly, axions as associated with the mentioned $U(1)$s breaking (including Majoron due to lepton-charge breaking) are all gauged away because they are also the Goldstone bosons responsible for the gauge symmetry breaking as usual.

A combined search for the Standard Model Higgs boson with the ATLAS detector at the LHC is presented. The data sets used correspond to integrated luminosities from $4.6{\mathrm{fb}}^{-1}$ to $4.9{\mathrm{fb}}^{-1}$ of proton-proton collisions collected at $\sqrt{s}=7\mathrm{TeV}$ in 2011. The Higgs boson mass ranges of 111.4 GeV to 116.6 GeV, 119.4 GeV to 122.1 GeV, and 129.2 GeV to 541 GeV are excluded at the 95% confidence level, while the range 120 GeV to 560 GeV is expected to be excluded in the absence of a signal. An excess of events is observed at Higgs boson mass hypotheses around 126 GeV with a local significance of 2.9 standard deviations ($\sigma$). The global probability for the background to produce an excess at least as significant anywhere in the entire explored Higgs boson mass range of 110–600 GeV is estimated to be $\sim 15\%$, corresponding to a significance of approximately $1\sigma$.

The maximally complicated arbitrary-dimensional “maximal” Galileon field equations simplify dramatically for symmetric configurations. Thus, spherical symmetry reduces the equations from the $D$- to the two-dimensional (Monge-Ampere) equation, axial symmetry to its cubic extension, etc. We can then obtain explicit solutions, such as spherical or axial waves, and relate them to the (known) general, but highly implicit, lower-$D$ solutions.

An equivalent formulation of the Gribov–Zwanziger theory accounting for the gauge fixing ambiguity in the Landau gauge is presented. The resulting action is constrained by a Slavnov-Taylor identity stemming from a nilpotent exact Becchi-Rouet-Stora-Tyutin (BRST) invariance which is spontaneously broken due to the presence of the Gribov horizon. This spontaneous symmetry breaking can be described in a purely algebraic way through the introduction of a pair of auxiliary fields which give rise to a set of linearly broken Ward identities. The Goldstone sector turns out to be decoupled. The underlying exact nilpotent BRST invariance allows us to employ BRST cohomology tools within the Gribov horizon to identify renormalizable extensions of gauge invariant operators. Using a simple toy model and appropriate Dirac bracket quantization, we discuss the time evolution invariance of the operator cohomology. We further comment on the unitarity issue in a confining theory, and stress that BRST cohomology alone is not sufficient to ensure unitarity, a fact that, although well known, is frequently ignored.

We propose a measure of order in the context of nonequilibrium field theory and argue that this measure, which we call relative configurational entropy (RCE), may be used to quantify the emergence of coherent low-entropy configurations, such as time-dependent or time-independent topological and nontopological spatially extended structures. As an illustration, we investigate the nonequilibrium dynamics of spontaneous symmetry breaking in three spatial dimensions. In particular, we focus on a model where a real scalar field, prepared initially in a symmetric thermal state, is quenched to a broken-symmetric state. For a certain range of initial temperatures, spatially localized, long-lived structures known as oscillons emerge in synchrony and remain until the field reaches equilibrium again. We show that the RCE correlates with the number density of oscillons, thus offering a quantitative measure of the emergence of nonperturbative spatiotemporal patterns that can be generalized to a variety of physical systems.

We investigate the effect of Lorentz-violating terms on Bhabha scattering in two distinct cases correspondent to vectorial and axial nonminimal couplings in quantum electrodynamics (QED). In both cases, we find significant modifications with respect to the usual relativistic result. Our results reveal an anisotropy of the differential cross section which implies new constraints on the possible Lorentz-violating terms.

In this paper, we derive corrections to the geodesic equation due to the $\kappa$-deformation of curved spacetime, up to the first order in the deformation parameter $a$. This is done by generalizing the method from our previous paper [Phys. Rev. D 84, 085020 (2011)] to include curvature effects. We show that the effect of $\kappa$-noncommutativity can be interpreted as an extra drag that acts on the particle while moving in this $\kappa$-deformed curved spacetime. We have derived the Newtonian limit of the geodesic equation and using this, we discuss possible bounds on the deformation parameter. We also derive the generalized uncertainty relations valid in the nonrelativistic limit of the $\kappa$-spacetime.

In Lorentz violating quantum electrodynamics (QED) it is known that a radiatively induced Chern-Simons term appears in the effective action for the gauge field, which is finite but undetermined. This ambiguity is shown to be absent in a condensed matter realization of such a theory in Weyl semi-metals due to the existence of a full microscopic model from which this effective theory emerges. Physically observable consequences such as birefringence are also discussed in this scenario.

Differential rotation induced by the $r$-mode instability can generate very strong toroidal fields in the core of accreting, millisecond spinning neutron stars. We introduce explicitly the magnetic damping terms in the evolution equations of the $r$-modes and solve them numerically in the Newtonian limit, to follow the development and growth of the internal magnetic field. We show that the strength of the latter can reach large values, $B\sim {10}^{14}\mathrm{G}$, in the core of the fastest accreting neutron stars. This is strong enough to induce a significant quadrupole moment of the neutron star mass distribution, corresponding to an ellipticity $|{ϵ}_{\mathrm{B}}|\sim {10}^{-8}$. If the symmetry axis of the induced magnetic field is not aligned with the spin axis, the neutron star radiates gravitational waves. We suggest that this mechanism may explain the upper limit of the spin frequencies observed in accreting neutron stars in low mass X-ray binaries. We discuss the relevance of our results for the search of gravitational waves.