We use Gaussian processes to map the expansion history of the universe in a model-independent manner from the Union2.1 supernovae data and then apply these reconstructed results to solve for the growth history. By comparing this to Baryon Oscillation Spectroscopic Survey and WiggleZ large-scale structure data we examine whether growth is determined wholly by expansion, with the measured gravitational growth index testing gravity without assuming a model for dark energy. A further model-independent analysis looks for redshift-dependent deviations of growth from the general relativity solution without assuming the growth index form. Both approaches give results consistent with general relativity.

Using the most recent data from the WMAP, ACT and SPT experiments, we update the constraints on models with oscillatory features in the primordial power spectrum of scalar perturbations. This kind of features can appear in models of inflation where slow-roll is interrupted, like multifield models. We also derive constraints for the case in which, in addition to cosmic microwave observations, we also consider the data on the spectrum of luminous red galaxies from the 7th SDSS catalog, and the SNIa Union Compilation 2 data. We have found that: (i) considering a model with features in the primordial power spectrum increases the agreement with data compared to the featureless “vanilla” $\Lambda \mathrm{CDM}$ model by $\Delta {\chi }^2=6.7$, representing an improvement with respect to the expected value $\Delta {\chi }^2=3$ for an equivalent model with three additional parameters; (ii) the uncertainty on the determination of the standard parameters is not degraded when features are included; (iii) the best fit for the features model locates the step in the primordial spectrum at a scale $k\simeq 0.005{\mathrm{Mpc}}^{-1}$, corresponding to the scale where the outliers in the WMAP7 data at $\ell =22$ and $\ell =40$ are located.; (iv) a distinct, albeit less statistically significant peak is present in the likelihood at smaller scales, whose presence might be related to the WMAP7 preference for a negative value of the running of the scalar spectral index parameter; (v) the inclusion of the LRG-7 data does not change significantly the best fit model, but allows to better constrain the amplitude of the oscillations.

Quantum decoherence and the transition to semiclassical behavior during inflation have been extensively considered in the literature. In this paper, we use a simple model to analyze the same process in ekpyrosis. Our result is that the quantum to classical transition would not happen during an ekpyrotic phase even for superhorizon modes, and therefore the fluctuations cannot be interpreted as classical. This implies the prediction of a scale-free power spectrum in an ekpyrotic/cyclic universe model requires more inspection.

Astrophysical black hole candidates are thought to be the Kerr black holes predicted by general relativity, but there is not yet clear evidence that the geometry of the space-time around these objects is really described by the Kerr metric. In order to confirm the Kerr black hole hypothesis, we have to observe strong gravity features and check that they are in agreement with the ones predicted by general relativity. In this paper, I study the broad $\mathrm{K}\alpha$ iron line, which is often seen in the x-ray spectrum of both stellar-mass and supermassive black hole candidates and whose shape is supposed to be strongly affected by the space-time geometry. As found in previous studies in the literature, there is a strong correlation between the spin parameter and the deformation parameter; that is, the line emitted around a Kerr black hole with a certain spin can be very similar to the one coming from the space-time around a non-Kerr object with a quite different spin. Despite that, the analysis of the broad $\mathrm{K}\alpha$ iron line is potentially more powerful than the continuum-fitting method, as it can put an interesting bound on possible deviations from the Kerr geometry independently of the value of the spin parameter and without additional measurements.

The observed sign of a deviation from the $e\mathrm{\text{−}}\mu$ universality in tau decays suggests family gauge bosons with an inverted mass hierarchy. Under the constraints from the observed $K^0\mathrm{\text{−}}{\overline{K}}^0$ and $D^0\mathrm{\text{−}}{\overline{D}}^0$ mixing, we investigate a possibility that a mass $M_{33}$ of the lightest gauge boson $A_3^3$ which couples with only the third generation quarks and leptons is of the order of TeV. It is concluded that $M_{33}\sim 1\mathrm{TeV}$ is possible if we adopt a specific model phenomenologically.

We study properties of two-color QCD at imaginary chemical potential ($\mu$) from the viewpoint of the Roberge-Weiss periodicity, the charge conjugation, and the pseudoreality. At $\mu =\pm i\pi T/2$, where $T$ is temperature, the system is symmetric under the combination of the charge conjugation $\mathcal{C}$ and the ${\mathbb{Z}}_2$ transformation. The symmetry, called $\mathcal{C}{\mathbb{Z}}_2$ symmetry, is preserved at lower $T$ but spontaneously broken at higher $T$. The Polyakov-loop extended Nambu-Jona-Lasinio model has the same properties as two-color QCD for $\mathcal{C}{\mathbb{Z}}_2$ symmetry and the pseudoreality. The nontrivial correlation between the chiral restoration and the deconfinement are investigated by introducing the entanglement vertex in the Polyakov-loop extended Nambu-Jona-Lasinio model. The order of $\mathcal{C}{\mathbb{Z}}_2$ symmetry breaking at the Roberge-Weiss end point is second order when the correlation is weak, but becomes first order when the correlation is strong. We also investigate the impact of the correlation on the phase diagram at real $\mu$.

First, we study the fit of the Higgs boson rates, based on all the latest collider data, in the effective framework for any extra fermion(s) (EF). The best-fit results are presented in a generic formalism allowing us to apply those for the test of any EF scenario under the assumption that the corrections to the Higgs couplings are coming exclusively from EF effects. The variations of the fit with each one of the five fundamental parameters are described, and the obtained fits can be better than in the Standard Model (SM). We show how the determination of the EF loop contributions to the Higgs couplings with photons and gluons is relying on the knowledge of the top and bottom Yukawa couplings (affected by EF mixings); for determining the latter coupling, the relevance of the investigation of the Higgs production in association with bottom quarks is emphasized. In the instructive approximation of a single EF, we find that the constraints from the fit already turn out to be quite predictive in both cases of an EF mixed or not with SM fermions, and especially when combined with the extra-quark (-lepton) mass bounds from direct EF searches at the LHC (LEP) collider. In the case of an unmixed extra quark (in the same color representation as SM quarks), nontrivial fit constraints are pointed out on the Yukawa couplings for masses up to $\sim 200\mathrm{TeV}$. In particular, we define the extra dysfermiophilia, which is predicted at 68.27% C.L. for any single extra quark (independently of its electric charge). Another result is that, among any components of SM multiplet extensions, the extra quark with a $-7/3$ electric charge is the one preferred by the present Higgs fit.

We customize the simulation code Fully Exclusive $W$, $Z$ Production to study $Z^{\prime }$ production at the LHC for both $\sqrt{s}=8\mathrm{TeV}$ and 14 TeV. Using the results of our simulation for several standard benchmark $Z^{\prime }$ models, we derive a semiempirical expression for the differential cross section that permits the determination of $Z^{\prime }$ couplings in a model-independent manner. We evaluate cross sections and other observables for large classes of models, including the common ${\mathrm{E}}_6$, left-right and $B-L$ models, as a function of model parameters. We also consider a hidden sector $Z^{\prime }$ that couples to standard model fermions via kinetic and mass mixing and serves as a mediator of isospin-violating interactions with dark matter. We combine the results of LHC $Z^{\prime }$ searches and dark matter direct detection experiments with global electroweak data to obtain mass-dependent constraints on the model parameters.

In this paper we examine thoroughly the Higgs boson to ${\mu }^{\mp }{\tau }^{\pm }$ decay via processes involving $R$ parity violating couplings. By means of full one-loop diagrammatic calculations, we found that even if known experimental constraints, particularly including the stringent sub-eV neutrino mass bounds, give strong restrictions on some of the $R$ parity violating parameters, the branching ratio could still achieve notable value in the admissible parameter space. Hence, the flavor violating leptonic decay is of interest to future experiments. We present here key results of our analysis. Based on the analysis, we give some comments on $h^0\to e^{\mp }{\mu }^{\pm }$ and $h^0\to e^{\mp }{\tau }^{\pm }$ also.

With anomalies found in cosmic ray observations and unsolved questions of the Standard Model of particle physics like the discrepancy in the muon’s anomalous magnetic moment, the idea of an $U(1)$ extension of the Standard Model arose. This extension allows for the interaction of dark matter by exchange of a photonlike massive force carrier $A^{\prime }$ not included in the Standard Model. We discuss the possibility to constrain the dark photon parameter space by using data taken from rare kaon decays. Therefore we analyze the decay $K\to \mu \nu A^{\prime }$ as a signal process and calculate the expected Standard Model background. Using these results we calculate new limits on the $A^{\prime }$ parameter space, providing motivations for new rare kaon decay experiments to extend the existing $A^{\prime }$ bounds.

We study the scattering of light pseudoscalar mesons $(\pi ,K)$ off charmed mesons $(D,D_s)$ in full lattice QCD. The $S$-wave scattering lengths are calculated using Lüscher’s finite volume technique. We use a relativistic formulation for the charm quark. For the light quark, we use domain-wall fermions in the valence sector and improved Kogut-Susskind sea quarks. We calculate the scattering lengths of isospin-$3/2D\pi$, $D_s\pi$, $D_{s}K$, isospin-0 $D\overline{K}$ and isospin-1 $D\overline{K}$ channels on the lattice. For the chiral extrapolation, we use a chiral unitary approach to next-to-leading order, which at the same time allows us to give predictions for other channels. It turns out that our results support the interpretation of the $D_{s0}^{*}(2317)$ as a $DK$ molecule. At the same time, we also update a prediction for the isospin breaking hadronic decay width $\Gamma (D_{s0}^{*}(2317)\to D_s\pi )$ to $(133\pm 22)\mathrm{keV}$.

The deconfinement phase transition in large-$N_c$ QCD is studied within the framework of an effective Polyakov-loop model, where the potential has a U(1) symmetry originating in the large-$N_c$ limit of a ${\mathrm{Z}}_{N_c}$-symmetric model. At the critical temperature, the shape of the effective potential allows the existence of Q-balls as position-dependent fluctuations of the Polyakov loop. Q-balls with spherical or axial symmetry are numerically obtained from the equations of motion of the effective model under consideration. The physical properties of these nontopological solitons (mass, charge, and size) are discussed, as well as their interpretation in terms of spinning “bubbles,” with various shapes, of deconfined matter surrounded by a confined environment.

Using a sample of $(225.3\pm 2.8)\times {10}^6$ $J/\psi$ decays collected with the BESIII detector at BEPCII, searches for invisible decays of $\eta$ and ${\eta }^{\prime }$ in $J/\psi \to \varphi \eta$ and $\varphi {\eta }^{\prime }$ are performed. Decays of $\varphi \to K^{+}{K}^{-}$ are used to tag the $\eta$ and ${\eta }^{\prime }$ decays. No signals above background are found for the invisible decays, and upper limits at the 90% confidence level are determined to be $2.6\times {10}^{-4}$ for the ratio $\frac{\mathcal{B}(\eta \to \mathrm{invisible})}{\mathcal{B}(\eta \to \gamma \gamma )}$ and $2.4\times {10}^{-2}$ for $\frac{\mathcal{B}({\eta }^{\prime }\to \mathrm{invisible})}{\mathcal{B}({\eta }^{\prime }\to \gamma \gamma )}$. These limits may be used to constrain light dark matter particles or spin-1 $U$ bosons.

We present measurements of lepton ($\ell$) angular distributions in top-quark ($t$) pair production and $t\overline{t}\to W^{+}b{W}^{-}\overline{b}\to {\ell }^{+}\nu b{\ell }^{-}\overline{\nu }\overline{b}$ decays produced in $p\overline{p}$ collisions at a center-of-mass energy of $\sqrt{s}=1.96\mathrm{TeV}$, where $\ell$ is an electron or muon. Using data corresponding to an integrated luminosity of $5.4{\mathrm{fb}}^{-1}$, collected with the D0 detector at the Fermilab Tevatron Collider, we measure for the first time the leptonic forward-backward asymmetry in dilepton final states and obtain $A_{\mathrm{FB}}^{\ell }=(5.8\pm 5.1(\mathrm{stat})\pm 1.3(\mathrm{syst}))\%$, corrected for detector acceptance. This is compared to the standard model prediction of $A_{\mathrm{FB}}^{\ell }(\mathrm{predicted})=(4.7\pm 0.1)\%$. A deviation from the standard model prediction as previously seen in a D0 measurement based on the analysis of the $\ell +\mathrm{\text{jets}}$ final state is not observed in these dilepton final states. The two results differ from each other by 1.4 standard deviations and are combined to obtain $A_{\mathrm{FB}}^{\ell }=(11.8\pm 3.2)\%$. Furthermore, we present a first study of the top-quark polarization.

I explain how conventional topological defects—the Abrikosov-Nielsen-Olesen string and domain walls—can acquire non-Abelian moduli localized on their world sheets. The setup is conceptually similar and generalizes that used by Witten for cosmic strings Witten [Nucl. Phys. B249, 557 (1985)].

We discuss the formation of scalar hair on Gauss-Bonnet solitons and black holes in five-dimensional anti-de Sitter space-time. We present new results on the static case and point out further details. We find that the presence of the Gauss-Bonnet term has an influence on the pattern of soliton solutions for small enough values of the electric charge. We also discuss rotating Gauss-Bonnet black holes with and without scalar hair.

We construct a new exact solution of the Einstein-Maxwell-dilaton field equations in five dimensions, which describes a system of two general charged and static black holes sitting at the two turning points of the Taub-bolt instanton. We show that in this case the conical singularities can be completely eliminated and the black hole system remains in static equilibrium. We show how to recover some of the known solutions in particular cases and also obtain as a new solution the extremal double-black hole solution on the Taub-bolt instanton. Finally, we compute the conserved charges and investigate some of the thermodynamic properties of this system.

Twisted geometry is a piecewise-flat geometry less rigid than Regge geometry. In loop gravity, it provides the classical limit for each step of the truncation utilized in the definition of the quantum theory. We define the torsionless spin connection of a twisted geometry. The difficulty given by the discontinuity of the triad is addressed by interpolating between triads. The curvature of the resulting spin connection reduces to the Regge curvature in the case of a Regge geometry.