We find that the viability of a cosmological model that incorporates two sterile neutrinos with masses around 1 eV each, as favored by global neutrino oscillation analyses including short baseline results, is significantly dependent on the choice of data sets included in the analysis and the ability to control the systematic uncertainties associated with these data sets. Our analysis includes a variety of cosmological probes including the cosmic microwave background ($\mathrm{WMAP}7+\mathrm{SPT}$), Hubble constant (HST), galaxy power spectrum (SDSS-DR7), and supernova distances (SDSS and Union2 compilations). In the joint observational analysis, our sterile neutrino model is equally favored as a $\Lambda \mathrm{CDM}$ model when using the MLCS light curve fitter for the supernova measurements, and strongly disfavored by the data at $\Delta {\chi }_{\mathrm{eff}}^2\approx 18$ when using the SALT2 fitter. When excluding the supernova measurements, the sterile neutrino model is disfavored by the other data sets at $\Delta {\chi }_{\mathrm{eff}}^2\approx 12$, and at best becomes mildly disfavored at $\Delta {\chi }_{\mathrm{eff}}^2\approx 3$ when allowing for curvature, evolving dark energy, additional relativistic species, running of the spectral index, and freedom in the primordial helium abundance. No single additional parameter accounts for most of this effect. Therefore, if laboratory experiments continue to favor a scenario with roughly eV mass sterile neutrinos, and if this becomes decisively disfavored by cosmology, then a more exotic cosmological model than explored here may become necessary.

We consider a static self-gravitating system consisting of perfect fluid with isometries of a ($D-2$)-dimensional maximally symmetric space in Lovelock gravity theory. A straightforward analysis of the time-time component of the equations of motion suggests a generalized mass function. A Tolman-Oppenheimer-Volkoff-like equation is obtained by using this mass function and gravitational equations. We investigate the maximum entropy principle in Lovelock gravity, and find that this Tolman-Oppenheimer-Volkoff equation can also be deduced from the so-called “maximum entropy principle” which was originally customized for Einstein gravity theory. This investigation manifests a deep connection between gravity and thermodynamics in this generalized gravity theory.

Realistic models of high-energy physics include multiple scalar fields. Renormalization requires that the fields have nonminimal couplings to the spacetime Ricci curvature scalar, and the couplings can be large at the energy scales of early-universe inflation. The nonminimal couplings induce a nontrivial field-space manifold in the Einstein frame, and they also yield an effective potential in the Einstein frame with nontrivial curvature. The ridges or bumps in the Einstein-frame potential can lead to primordial non-Gaussianities of observable magnitude. We develop a covariant formalism to study perturbations in such models and calculate the primordial bispectrum. As in previous studies of non-Gaussianities in multifield models, our results for the bispectrum depend sensitively on the fields’ initial conditions.

Primordial magnetic fields of cosmologically interesting field strengths can be generated from gravitationally coupled electrodynamics during inflation. As the cosmological constraints require this to be power law inflation it is not possible to generate at the same time the curvature perturbation from inflation. Therefore here a completion is considered whereby the large scale magnetic field is generated during inflation and the primordial curvature mode in a subsequent era from a curvaton field. It is found that constraints on the model to obtain strong magnetic fields and those to suppress the amplitude of the curvature perturbation generated during inflation can be simultaneously satisfied for magnetic seed fields $B_s\gtrsim {10}^{-30}\mathrm{G}$.

Using the chiral representation for spinors we present a particularly transparent way to generate the most general spinor dynamics in a theory where gravity is ruled by the Einstein-Cartan-Holst action. In such theories torsion need not vanish, but it can be reinterpreted as a four-fermion self-interaction within a torsion-free theory. The self-interaction may or may not break parity invariance, and may contribute positively or negatively to the energy density, depending on the couplings considered. We then examine cosmological models ruled by a spinorial field within this theory. We find that while there are cases for which no significant cosmological novelties emerge, the self-interaction can also turn a mass potential into an upside-down Mexican hat potential. Then, as a general rule, the model leads to cosmologies with a bounce, for which there is a maximal energy density, and where the cosmic singularity has been removed. These solutions are stable, and range from the very simple to the very complex.

At TeV energies, the gamma-ray horizon of the Universe is limited to redshifts $z\ll 1$, and, therefore, any observation of TeV radiation from a source located beyond $z=1$ would call for a revision of the standard paradigm. While robust observational evidence for TeV sources at redshifts $z\ge 1$ is lacking at present, the growing number of TeV blazars with redshifts as large as $z\simeq 0.5$ suggests the possibility that the standard blazar models may have to be reconsidered. We show that TeV gamma rays can be observed even from a source at $z\ge 1$, if the observed gamma rays are secondary photons produced in interactions of high-energy protons originating from the blazar jet and propagating over cosmological distances almost rectilinearly. This mechanism was initially proposed as a possible explanation for the TeV gamma rays observed from blazars with redshifts $z\sim 0.2$, for which some other explanations were possible. For TeV gamma-ray radiation detected from a blazar with $z\ge 1$, this model would provide the only viable interpretation consistent with conventional physics. It would also have far-reaching astronomical and cosmological ramifications. In particular, this interpretation would imply that extragalactic magnetic fields along the line of sight are very weak, in the range ${10}^{-17}\mathrm{G}<B<{10}^{-14}\mathrm{G}$, assuming random fields with a correlation length of 1 Mpc, and that acceleration of $E\ge {10}^{17}\mathrm{eV}$ protons in the jets of active galactic nuclei can be very effective.

Recently a new—quantum motivated—theory of gravity has been proposed that modifies the standard Newtonian potential at large distances when spherical symmetry is considered. Accordingly, Newtonian gravity is altered by adding an extra Rindler acceleration term that has to be phenomenologically determined. Here we consider a standard and a power-law generalization of the Rindler modified Newtonian potential. The new terms in the gravitational potential are hypothesized to play the role of dark matter in galaxies. Our galactic model includes the mass of the integrated gas, and stars for which we consider three stellar mass functions (Kroupa, diet-Salpeter, and free mass model). We test this idea by fitting rotation curves of seventeen low surface brightness galaxies from the HI Nearby Galaxy Survey (THINGS). We find that the Rindler parameters do not perform a suitable fit to the rotation curves in comparison to standard dark matter profiles (Navarro-Frenk-White and Burkert) and, in addition, the computed parameters of the Rindler gravity show a high spread, posing the model as a nonacceptable alternative to dark matter.

We confront the little Higgs theory with the LHC Higgs search data (up to $17{\mathrm{fb}}^{-1}$ of the combined 7 and 8 TeV run). Considering some typical models, namely, the littlest Higgs model, the littlest Higgs model with $T$ parity (LHT-A and LHT-B), and the simplest little Higgs model, we scan over the parameter space in the region allowed by current experiments. We find that in these models the inclusive and exclusive (via gluon-gluon fusion) diphoton and $Z{Z}^{*}$ signal rates of the Higgs boson are always suppressed and approach the standard model predictions for a large-scale $f$. Thus, the $Z{Z}^{*}$ signal rate is within the $1\sigma$ range of the experimental data while the inclusive diphoton signal rate is always outside the $2\sigma$ range. Especially, in the LHT-A the diphoton signal rate is outside the $3\sigma$ range of the experimental data for $f<800\mathrm{GeV}$. We also perform a global ${\chi }^2$ fit to the available LHC and Tevatron Higgs data, and find that these models provide no better global fit to the whole data set (only for some special channels a better fit can be obtained, especially in the LHT-B).

We extract quark masses ${\overline{m}}_q$ ($q=b$, $c$) from the evaluation of the masses of quarkonia ${\rm Y}(1S)$ and $J/\psi (1S)$, performed in two analytic QCD models, and in perturbative QCD in two renormalization schemes. In analytic QCD the running coupling has no unphysical singularities in the low-momentum regime. We apply the analytic model of Shirkov et al. [analytic perturbation theory (APT)], extended by Bakulev et al. [fractional analytic perturbation theory (FAPT)], and the two-delta analytic model ($2\delta \mathrm{anQCD}$). The latter, in contrast to (F)APT, at higher energies basically coincides with the perturbative QCD (in the same scheme). We use the renormalon-free mass ${\overline{m}}_q$ as input. The separation of the soft and ultrasoft parts of the binding energy $E_{q\overline{q}}$ is performed by the requirement of the cancellation of the leading infrared renormalon. The analysis in the $2\delta \mathrm{anQCD}$ model indicates that the low-momentum ultrasoft regime is important for the extraction of the masses ${\overline{m}}_q$, especially ${\overline{m}}_b$. The $2\delta \mathrm{anQCD}$ model gives us clues on how to estimate the influence of the ultrasoft sector on ${\overline{m}}_q$ in general. These effects lead to relatively large values ${\overline{m}}_b\approx 4.35\pm 0.08\mathrm{GeV}$ in the $2\delta \mathrm{anQCD}$ model, which, however, are compatible with recent lattice calculations. In perturbative QCD in the $\overline{\mathrm{MS}}$ scheme these effects are even stronger and give larger uncertainties in ${\overline{m}}_b$. The (F)APT model gives small ultrasoft effects and the extracted values of ${\overline{m}}_b$ agree with those in most of the literature (${\overline{m}}_b\approx 4.2\mathrm{GeV}$). The extracted values of ${\overline{m}}_c$ in all four models are about 1.26–1.27 GeV and agree well with those in the literature.

We propose that some puzzles in the semileptonic decays of $B$ mesons to the broad ${\overline{D}}^{**}$ states could be clarified by studying at LHCb the corresponding decays with strange mesons $B_s^0\to D_{s0}^{-}$. In particular, we point out that the nonleptonic decay $B_s^0\to D_{s0}^{-}{\pi }^{+}$ and the like, being Class I decays (where factorization is expected to hold), could be a first step in this direction. The interpretation of results in both semileptonic and nonleptonic decays will presumably be easier due to the narrowness of the $D_{s0}^{-}$ state. On the other hand, we make a careful and detailed study of the experimental and theoretical situation in the case of the wide nonstrange ${\overline{D}}^{**}$ case, and we update previous analyses.

We study the $\eta$ transitions between $\psi (4040/4160)$ and $J/\psi$ by introducing charmed meson loops in an effective Lagrangian approach to enhance the decay amplitudes. The branching fractions $\mathcal{B}[\psi (4040)\to J/\psi \eta ]$ and $\mathcal{B}[\psi (4160)\to J/\psi \eta ]$ estimated in this paper can remarkably explain the experimental measurements of Belle and BESIII within a reasonable parameter range. The ${\eta }^{\prime }$ transition between $\psi (4160)$ and $J/\psi$ is also investigated, and the branching fraction is under the upper limit of CLEO, which can be tested by future experiments.

Two aspects of high-energy $p\mathrm{\text{−}}p$ collisions share common phenomenological elements: (a) A correlation between jet production and $p\mathrm{\text{−}}p$ centrality is suggested by the transverse partonic structure of hadrons inferred from deep-inelastic scattering data. (b) The underlying event (UE) is defined as the final-state particles complementary to a triggered high-energy dijet. An observable common to both topics is a variation of the so-called transverse multiplicity $N_{\perp }$ with a $p_{t,\mathrm{trig}}$ dijet trigger. In this paper we test assumptions associated with $p\mathrm{\text{−}}p$ collision centrality and the UE, and determine the nature of the UE and explore the relation between jet production and $p\mathrm{\text{−}}p$ centrality. We use the two-component model (TCM) of spectra and correlations derived from 200 GeV $p\mathrm{\text{−}}p$ collisions to construct a simulated particle distribution on $(p_t,n_{\mathrm{ch}})$. The simulation is used to predict the $N_{\perp }$ response to $p_{t,\mathrm{trig}}$. Additionally, we use the measured $p_t$ spectrum $n_{\mathrm{ch}}$ dependence to explore the effect of changing $p\mathrm{\text{−}}p$ centrality. The results show that TCM provides a good description of $N_{\perp }$ vs $p_{t,\mathrm{trig}}$ and the $N_{\perp }(p_t)$ spectrum, and the relation of $N_{\perp }$ to $p_t$ and $p_{t,\mathrm{trig}}$ departs from assumptions. The $p_t$ spectrum TCM combined in this analysis with measured minimum-bias $p\mathrm{\text{−}}p$ angular correlations suggests that the UE includes a substantial contribution from the triggered dijet in addition to the contribution from projectile fragmentation (beam-beam remnants). The jet contribution to $N_{\perp }$ may represent a universal large-angle base common to all dijets that extends across $2\pi$ azimuth. The analysis further suggests that $p\mathrm{\text{−}}p$ centrality is not controlled significantly by $p_{t,\mathrm{trig}}$ but may be correlated to some extent with an imposed $n_{\mathrm{ch}}$ condition, depending on the role of fluctuations. Future correlation studies may better determine the role of $p\mathrm{\text{−}}p$ centrality. These results may have implications for ongoing RHIC analysis and LHC searches for physics beyond the standard model.

We report on a study of the isospin-violating and isospin-conserving decays of the $J/\psi$ and ${\psi }^{\prime }$ charmonium state to $\Lambda \overline{\Lambda }{\pi }^0$ and $\Lambda \overline{\Lambda }\eta$, respectively. The data are based on 225 million $J/\psi$ and 106 million ${\psi }^{\prime }$ events that were collected with the BESIII detector. The most accurate measurement of the branching fraction of the isospin-violating process $J/\psi \to \Lambda \overline{\Lambda }{\pi }^0$ is obtained, and the isospin-conserving processes $J/\psi \to \Lambda \overline{\Lambda }\eta$ and ${\psi }^{\prime }\to \Lambda \overline{\Lambda }\eta$ are observed for the first time. The branching fractions are measured to be $\mathcal{B}(J/\psi \to \Lambda \overline{\Lambda }{\pi }^0)=(3.78\pm {0.27}_{\mathrm{stat}}\pm {0.30}_{\mathrm{sys}})\times {10}^{-5}$, $\mathcal{B}(J/\psi \to \Lambda \overline{\Lambda }\eta )=(15.7\pm {0.80}_{\mathrm{stat}}\pm {1.54}_{\mathrm{sys}})\times {10}^{-5}$ and $\mathcal{B}({\psi }^{\prime }\to \Lambda \overline{\Lambda }\eta )=(2.48\pm {0.34}_{\mathrm{stat}}\pm {0.19}_{\mathrm{sys}})\times {10}^{-5}$. No significant signal events are observed for ${\psi }^{\prime }\to \Lambda \overline{\Lambda }{\pi }^0$ decay resulting in an upper limit of the branching fraction of $\mathcal{B}({\psi }^{\prime }\to \Lambda \overline{\Lambda }{\pi }^0)<0.29\times {10}^{-5}$ at the 90% confidence level. The two-body decay of $J/\psi \to \Sigma (1385{)}^0\overline{\Lambda }+\mathrm{c}.\mathrm{c}.$ is searched for, and the upper limit is $B(J/\psi \to \Sigma (1385{)}^0\overline{\Lambda }+\mathrm{c}.\mathrm{c}.)<0.82\times {10}^{-5}$ at the 90% confidence level.

A search motivated by supersymmetric models with light top squarks is presented using proton-proton collision data recorded with the CMS detector at a center-of-mass energy of $\sqrt{s}=7\mathrm{TeV}$ during 2011, corresponding to an integrated luminosity of $4.98{\mathrm{fb}}^{-1}$. The analysis is based on final states with a single lepton, $b$-quark jets, and missing transverse energy. Standard model yields are predicted from data using two different approaches. The observed event numbers are found to be compatible with these predictions. Results are interpreted in the context of the constrained minimal supersymmetric standard model and of a simplified model with four top quarks in the final state.

In this paper we show how the equations of motion of a superfield, which makes its appearance in a path-integral approach to classical mechanics, can be derived without the need of the least-action principle.

A tensor-network variational formalism of thermofield dynamics is introduced. The formalism relates the original Hilbert space with its tilde space by a product of two copies of a tensor network. Then, their interface becomes an event horizon, and the logarithm of the tensor rank corresponds to the black hole entropy. Eventually, a multiscale entanglement renormalization ansatz reproduces an anti–de Sitter black hole at finite temperature. Our finding shows rich functionalities of multiscale entanglement renormalization ansatz as efficient graphical representation of AdS/CFT correspondence.

The top-Higgs system, consisting of top-quark (left-handed doublet and right-handed singlet) and Higgs boson kinetic terms, with gauge fields set to zero, has an exact (modulo total divergences) symmetry where both fermion and Higgs fields are shifted and mixed in a supersymmetric fashion. The full Higgs-Yukawa interaction and Higgs potential, including additional $\sim 1/{\Lambda }^2$ Nambu–Jona-Lasinio-like interactions, also has this symmetry to $\mathcal{O}(1/{\Lambda }^4)$, up to null operators. Thus, the interaction Lagrangian can be viewed as a power series in $\mathcal{O}(1/{\Lambda }^2)$. The symmetry involves the interplay of the Higgs quartic interaction with the Higgs-Yukawa interaction and implies the relationship $\lambda =\frac{1}{2}{g}_t^2$ between the top-Yukawa coupling $g_t$ and Higgs quartic coupling $\lambda$ at a high energy scale $\Lambda \gtrsim$ few TeV. We interpret this to be a new physics scale. The top quark is massless in the symmetric phase, satisfying the Nambu-Goldstone theorem. The fermionic shift part of the current is $\propto (1-H^{†}H/v^2)$, owing to the interplay of $\lambda$ and $g_t$, and vanishes in the broken phase. Hence, the Nambu-Goldstone theorem is trivially evaded in the broken phase and the top quark becomes heavy. We have $m_t=m_h$, subject to radiative corrections that can, in principle, pull the Higgs into concordance with experiment.

The hydrodynamic description of a superfluid is usually based on a two-fluid picture. We compute the basic properties of the relativistic two-fluid system from the underlying microscopic physics of a relativistic ${\phi }^4$ complex scalar field theory. We work at nonzero but small temperature and weak coupling, and we neglect dissipation. We clarify the relationship between different formulations of the two-fluid model and how they are parametrized in terms of partly redundant current and momentum four-vectors. As an application, we compute the velocities of first and second sound at small temperatures and in the presence of a superflow. While our results are of a very general nature, we also comment on their interpretation as a step towards the hydrodynamics of the color-flavor locked state of quark matter, which, particularly in the presence of kaon condensation, appears to be a complicated multicomponent fluid.