The mass function of the nonperturbative quark propagator in $SU(3)$ gauge theory shows only a weak dependence on the vortex content of the gauge configurations. Of particular note is the survival of dynamical mass generation on vortex-free configurations having a vanishing string tension. This admits the possibility that mass generation associated with dynamical chiral symmetry breaking persists without confinement. In this paper we examine the low-lying ground state hadron spectrum of the $\pi$, $\rho$, $N$ and $\Delta$ and discover that while dynamical mass generation persists in the vortex-free theory, it is not connected to dynamical chiral symmetry breaking. In this way, center vortices in $SU(3)$ gauge theory are intimately linked to both confinement and dynamical chiral symmetry breaking.

We present a determination of parton distribution functions (ABM11) and the strong coupling constant ${\alpha }_s$ at next-to-leading order and next-to-next-to-leading order (NNLO) in QCD based on world data for deep-inelastic scattering and fixed-target data for the Drell-Yan process. The analysis is performed in the fixed-flavor number scheme for $n_f=3$, 4, 5 and uses the $\overline{\mathrm{MS}}$ scheme for ${\alpha }_s$ and the heavy-quark masses. At NNLO we obtain the value ${\alpha }_s(M_Z)=0.1134\pm 0.0011$. The fit results are used to compute benchmark cross sections at hadron colliders to NNLO accuracy and to compare to data from the LHC.

The recent measurement of a nonzero neutrino mixing angle ${\theta }_{13}$ requires a modification of the tri-bimaximal mixing pattern that predicts a zero value for it. We propose a new neutrino mixing pattern based on a spontaneously broken $A_4$ flavor symmetry and a type-I seesaw mechanism. Our model allows for approximate tri-bimaximal mixing and nonzero ${\theta }_{13}$, and contains a natural way to implement low- and high-energy $CP$ violations in neutrino oscillations, and leptogenesis with a renormalizable Lagrangian. Both normal and inverted mass hierarchies are permitted within $3\sigma$ experimental bounds, with the prediction of small (large) deviations from maximality in the atmospheric mixing angle for the normal (inverted) case. Interestingly, we show that the inverted case is excluded by the global analysis in $1\sigma$ experimental bounds, while the most recent MINOS data seem to favor the inverted case. Our model make predictions for the Dirac $CP$ phase in the normal and inverted hierarchies, which can be tested in near-future neutrino oscillation experiments. Our model also predicts the effective mass $|m_{ee}|$ measurable in neutrinoless double beta decay to be in the range $0.04\lesssim |m_{ee}|\lesssim 0.15\mathrm{eV}$ for the normal hierarchy and $0.06\lesssim |m_{ee}|\lesssim 0.11\mathrm{eV}$ for the inverted hierarchy, both of which are within the sensitivity of the next generation experiments.

The invariant mass spectrum of the ${\eta }^{\prime }{\pi }^{+}{\pi }^{-}$ final state produced in two-photon collisions is obtained using a $673{\mathrm{fb}}^{-1}$ data sample collected in the vicinity of the ${\rm Y}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. We observe a clear signal of the ${\eta }_c(1S)$ and measure its mass and width to be $M({\eta }_c(1S))=(2982.7\pm 1.8(\mathrm{stat})\pm 2.2(\mathrm{syst})\pm 0.3(\mathrm{\text{model}}))\mathrm{MeV}/c^2$ and $\Gamma ({\eta }_c(1S))=({37.8}_{-5.3}^{+5.8}(\mathrm{stat})\pm 2.8(\mathrm{syst})\pm 1.4(\mathrm{\text{model}}))\mathrm{MeV}/c^2$. The third error is an uncertainty due to possible interference between the ${\eta }_c(1S)$ and a nonresonant component. We also report the first evidence for $\eta (1760)$ decay to ${\eta }^{\prime }{\pi }^{+}{\pi }^{-}$; we find two solutions for its parameters, depending on the inclusion or not of the $X(1835)$, whose existence is of marginal significance in our data. From a fit to the mass spectrum using coherent $X(1835)$ and $\eta (1760)$ resonant amplitudes, we set a 90% confidence level upper limit on the product ${\Gamma }_{\gamma \gamma }\mathcal{B}({\eta }^{\prime }{\pi }^{+}{\pi }^{-})$ for the $X(1835)$.

We use the formalism of geometrothermodynamics to derive fundamental thermodynamic equations that are used to construct general relativistic cosmological models. In particular, we show that the simplest possible fundamental equation, which corresponds in geometrothermodynamics to a system with no internal thermodynamic interaction, describes the different fluids of the standard model of cosmology. In addition, a particular fundamental equation with internal thermodynamic interaction is shown to generate a new cosmological model that correctly describes the dark sector of the Universe and contains as a special case the generalized Chaplygin gas model.

We propose a cosmological inflationary scenario based on the supergravity-embedded Standard Model supplemented by the right-handed neutrinos. We show that with an appropriate Kähler potential the $L\mathrm{\text{−}}{H}_u$ direction gives rise to successful inflation that is similar to the recently proposed gravitationally coupled Higgs inflation model but is free from the unitarity problem. The mass scale $M_R$ of the right-handed neutrinos is subject to the seesaw relation and the present $2\mathrm{\text{−}}\sigma$ constraint from the $\mathrm{WMAP}7-\mathrm{BAO}-H_0$ data sets its lower bound $M_R\gtrsim 1\mathrm{TeV}$. Generation of the baryon asymmetry is naturally implemented in this model. We expect that within a few years new observational data from the Planck satellite will clearly discriminate this model from other existing inflationary models arising from the same Lagrangian, and possibly yield stringent constraints on $M_R$.

We discuss lepton flavor violating processes induced in the production and decay of heavy right-handed neutrinos at the LHC. Such particles appear in left-right symmetrical extensions of the standard model as the messengers of neutrino mass generation, and can have masses at the TeV scale. We determine the expected sensitivity on the right-handed neutrino mixing matrix, as well as on the right-handed gauge boson and heavy neutrino masses. By comparing the sensitivity of the LHC with that of searches for low energy lepton flavor violating processes, we identify favorable areas of the parameter space to explore the complementarity between lepton flavor violating at low and high energies.

Dynamical dark matter (DDM) is a new framework for dark-matter physics in which the dark sector comprises an ensemble of individual component fields which collectively conspire to act in ways that transcend those normally associated with dark matter. Because of its nontrivial structure, this DDM ensemble—unlike most traditional dark-matter candidates—cannot be characterized in terms of a single mass, decay width, or set of scattering cross sections, but must instead be described by parameters which describe the collective behavior of its constituents. Likewise, the components of such an ensemble need not be stable so long as lifetimes are balanced against cosmological abundances across the ensemble as a whole. In this paper, we investigate the prospects for identifying a DDM ensemble at the LHC and for distinguishing such a dark-matter candidate from the candidates characteristic of traditional dark-matter models. In particular, we focus on DDM scenarios in which the component fields of the ensemble are produced at colliders alongside some number of standard-model particles via the decays of additional heavy fields. The invariant-mass distributions of these standard-model particles turn out to possess several unique features that cannot be replicated in most traditional dark-matter models. We demonstrate that in many situations it is possible to differentiate between a DDM ensemble and a traditional dark-matter candidate on the basis of such distributions. Moreover, many of our results also apply more generally to a variety of other extensions of the standard model which involve multiple stable or metastable neutral particles.

We study the interpretation of lattice data about the thermodynamics of the deconfinement phase of $SU(3)$ Yang-Mills theory, in terms of gluon quasiparticles propagating in a background of a Polyakov loop. A potential for the Polyakov loop, inspired by the strong coupling expansion of the QCD action, is introduced; the Polyakov loop is coupled to transverse gluon quasiparticles by means of a gaslike effective potential. This study is useful to identify the effective degrees of freedom propagating in the gluon medium above the critical temperature. A main general finding is that a dominant part of the phase transition dynamics is accounted for by the Polyakov loop dynamics; hence, the thermodynamics can be described without the need for diverging or exponentially increasing quasiparticle masses as $T\to T_c$, at variance respect to standard quasiparticle models.

In this work, we perform the one-loop calculation of the scalar and pseudoscalar form factors in the framework of $U(3)$ chiral perturbation theory with explicit tree level exchanges of resonances. The meson-meson scattering calculation from Guo and Oller [Phys. Rev. D 84, 034005 (2011)] is extended as well. The spectral functions of the nonet scalar-scalar ($SS$) and pseudoscalar-pseudoscalar ($PP$) correlators are constructed by using the corresponding form factors. After fitting the unknown parameters to the scattering data, we discuss the resonance content of the resulting scattering amplitudes. We also study spectral-function sum rules in the $SS-SS$, $PP-PP$, and $SS-PP$ sectors as well as semilocal duality from scattering. The former relate the scalar and pseudoscalar spectra between themselves while the latter mainly connects the scalar spectrum with the vector one. Finally we investigate these items as a function of $N_C$ for $N_C>3$. All these results pose strong constraints on the scalar dynamics and spectroscopy that are discussed. They are successfully fulfilled by our meson-meson scattering amplitudes and spectral functions.

We consider $1+1$ dimensional $SU(N)$ gauge theory coupled to a multiplet of massive Dirac fermions transforming in the adjoint representation of the gauge group. The only global symmetry of this theory is a $U(1)$ associated with the conserved Dirac fermion number, and we study the theory at variable, nonzero densities. The high density limit is characterized by a deconfined Fermi surface state with Fermi wave vector equal to that of free gauge-charged fermions. Its low energy fluctuations are described by a coset conformal field theory with central charge $c=(N^2-1)/3$ and an emergent $\mathcal{N}=(2,2)$ supersymmetry: the $U(1)$ fermion number symmetry becomes an $R$-symmetry. We determine the exact scaling dimensions of the operators associated with Friedel oscillations and pairing correlations. For $N>2$, we find that the symmetries allow relevant perturbations to this state. We discuss aspects of the $N\to \infty$ limit, and its possible dual description in ${\mathrm{AdS}}_3$ involving string theory or higher-spin gauge theory. We also discuss the low density limit of the theory by computing the low lying bound state spectrum of the large $N$ gauge theory numerically at zero density, using discretized light cone quantization.

We discuss how to obtain $\theta$-exact Seiberg-Witten maps by expanding in the gauge coupling constant or, equivalently, in the number of ordinary gauge fields. We do so for arbitrary compact gauge groups in arbitrary unitary representations. For gauge and matter fields, we fully work out $\theta$-exact nonhybrid Seiberg-Witten maps up to order three in the number of ordinary gauge fields.

Nonrelativistic conformal groups, indexed by $l=\frac{N}{2}$, are analyzed. Under the assumption that the mass parametrizing the central extension is nonvanishing, the coadjoint orbits are classified and described in terms of convenient variables. It is shown that the corresponding dynamical system describes, within Ostrogradski framework, the nonrelativistic particle obeying ($N+1$)-th order equation of motion. As a special case, the Schrödinger group and the standard Newton equations are obtained for $N=1$ ($l=\frac{1}{2}$).

We study the dynamics of weakly coupled non-Abelian plasmas within the frameworks of classical-statistical lattice gauge theory and kinetic theory. We focus on a class of systems which are highly occupied, isotropic at all times and initially characterized by a single momentum scale. These represent an idealized version of the situation in relativistic heavy-ion collisions in the color glass condensate picture, where on a time scale $1/Q_s$ after the collision of heavy nuclei a longitudinally expanding plasma characterized by the saturation scale $Q_s$ is formed. Our results indicate that the system evolves according to a turbulent Kolmogorov cascade in the classical regime. Taking this into account, the kinetic description is able to reproduce characteristic features of the evolution correctly.

The features of the scattering of massive neutral particles propagating in the field of a gravitational plane wave are compared with those characterizing their interaction with an electromagnetic radiation field. The motion is geodesic in the former case, whereas in the case of an electromagnetic pulse it is accelerated by the radiation field filling the associated spacetime region. The interaction with the radiation field is modeled by a force term entering the equations of motion proportional to the 4-momentum density of radiation observed in the particle’s rest frame. The corresponding classical scattering cross sections are evaluated too.

We study the hydrostatic equilibrium structure of compact stars in the Eddington-inspired Born-Infeld gravity recently proposed by Bañados and Ferreira [Phys. Rev. Lett. 105, 011101 (2010)]. We also develop a framework to study the radial perturbations and stability of compact stars in this theory. We find that the standard results of stellar stability still hold in this theory. The frequency square of the fundamental oscillation mode vanishes for the maximum-mass stellar configuration. The dependence of the oscillation mode frequencies on the coupling parameter $\kappa$ of the theory is also investigated. We find that the fundamental mode is insensitive to the value of $\kappa$, while higher-order modes depend more strongly on $\kappa$.

It is shown that for a generic electrovacuum spacetime, electromagnetic radiation produces vorticity of worldlines of observers in a Bondi-Sachs frame. Such an effect (and the ensuing gyroscope precession with respect to the lattice) which is a reminiscence of generation of vorticity by gravitational radiation, may be linked to the nonvanishing of components of the Poynting and the super-Poynting vectors on the planes othogonal to the vorticity vector. The possible observational relevance of such an effect is commented upon.

The recently proposed Hořava-Lifshitz theory of gravity is analyzed from the quantum cosmology point of view. By employing usual quantum cosmology techniques, we study the quantum Friedmann-Lemaître-Robertson-Walker universe filled with radiation in the context of Hořava-Lifshitz gravity. We find that this universe is quantum mechanically nonsingular in two different ways: the expectation value of the scale factor $⟨a⟩(t)$ never vanishes and, if we abandon the detailed balance condition suggested by Hořava, the quantum dynamics of the universe is uniquely determined by the initial wave packet and no boundary condition at $a=0$ is necessary.

Robust arguments predict that a hadron-quark mixed phase may exist in the cores of some “neutron” stars. Such a phase forms a crystalline lattice with a shear modulus higher than that of the crust due to the high density and charge separation, even allowing for the effects of charge screening. This may lead to strong continuous gravitational-wave emission from rapidly rotating neutron stars and gravitational-wave bursts associated with magnetar flares and pulsar glitches. We present the first detailed calculation of the shear modulus of the mixed phase. We describe the quark phase using the bag model plus first-order quantum chromodynamics corrections and the hadronic phase using relativistic mean-field models with parameters allowed by the most massive pulsar. Most of the calculation involves treating the “pasta phases” of the lattice via dimensional continuation, and we give a general method for computing dimensionally continued lattice sums including the Debye model of charge screening. We compute all the shear components of the elastic modulus tensor and angle average them to obtain the effective (scalar) shear modulus for the case where the mixed phase is a polycrystal. We include the contributions from changing the cell size, which are necessary for the stability of the lower-dimensional portions of the lattice. Stability also requires a minimum surface tension, generally tens of $\mathrm{MeV}{\mathrm{fm}}^{-2}$ depending on the equation of state. We find that the shear modulus can be a few times ${10}^{33}\mathrm{erg}{\mathrm{cm}}^{-3}$, two orders of magnitude higher than the first estimate, over a significant fraction of the maximum mass stable star for certain parameter choices.

We have previously studied [1,6] the time dependence of a $B^0-{\overline{B}}^0$ mixture in terms of its density matrix $\rho (t)=N(t)(\mathbb{1}+\overrightarrow{\zeta }(t)·\overrightarrow{\sigma })/2$. The requirement that $\zeta (t)$, the absolute value of the Stokes vector $\overrightarrow{\zeta }(t)$, should evolve monotonically from its initial value $\zeta (0)=0$ to its final value $\zeta (\infty )=1$ was shown to lead to an upper bound on the $CP$ violating overlap $\delta =⟨B_L|B_S⟩$. In the present paper, we consider the entropy variable $S=-\mathrm{tr}(\tilde{\varrho }{log}_2(\tilde{\varrho }))$, where $\tilde{\varrho }=\varrho /N$, as an alternative measure of mixing. We show that exactly the same upper bound emerges from the requirement that the flow of entropy is unidirectional ($dS/dt<0$). We compare the entropic current $dS/dt$ with and without $CP$ violation and identify certain physical features that appear when the bound on $\delta$ is violated.