We examine the dark energy and matter densities allowed by precision measurements of distances out to various redshifts, in the presence of spatial curvature and (near) arbitrary behavior of the dark energy equation of state. Degeneracies among the parameters permit a remarkably large variation in their values when using only distance measurements of the late-time universe and making no assumptions about the dark energy or curvature. Going beyond distance measurements to a lower limit on the growth of structure bounds the allowed region significantly but still leaves considerable freedom to match a flat $\Lambda$ Cold Dark Matter model with dark energy very different from a cosmological constant. The combination of distances with Hubble parameter, gravitational lensing or other large-scale structure data is essential to determining the cosmological model robustly.

If the dark matter in the universe is a self-gravitating Bose-Einstein condensate (BEC) with quartic self-interaction described by the stochastic Gross-Pitaevskii-Poisson system, the adhesion model, the Burgers equation and the cosmological Kardar-Parisi-Zhang (KPZ) equation that have been introduced heuristically to solve the problems inherent to cold dark matter (CDM) models find a natural justification and an interesting generalization.

The gravitational aether theory is a modification of general relativity that decouples vacuum energy from gravity, and thus can potentially address the cosmological constant problem. The classical theory is distinguishable from general relativity only in the presence of relativistic pressure (or vorticity). Since the interior of neutron stars has high pressure and as their mass and radius can be measured observationally, they are the perfect laboratory for testing the validity of the aether theory. In this paper, we solve the equations of stellar structure for the gravitational aether theory and find the predicted mass-radius relation of nonrotating neutron stars using two different realistic proposals for the equation of state of nuclear matter. We find that the maximum neutron-star mass predicted by the aether theory is 12%–16% less than the maximum mass predicted by general relativity assuming these two equations of state. We also show that the effect of aether is similar to modifying the equation of state in general relativity. The effective pressure of the neutron star given by the aether theory at a fiducial density differs from the values given by the two nuclear equations of state to an extent that can be constrained using future gravitational wave observations of neutron stars in compact systems. This is a promising way to test the aether theory if further progress is made in constraining the equation of state of nuclear matter in densities above the nuclear saturation density.

In order to better understand the fundamental issue regarding the compatibility between the quark-shell picture and that of resonances in meson-nucleon scattering in large $N_c$ QCD we extend the work of Cohen and Lebed on mixed symmetric $\ell =1$ baryons to analyze excited states with $\ell =3$. We give an explicit proof on the degeneracy of mass eigenvalues of a simple Hamiltonian including operators up to order $\mathcal{O}(N_c^0)$, i.e., neglecting $1/N_c$ corrections in the quark-shell picture in the large $N_c$ limit. We obtain three sets of degenerate states with $\ell =3$, as in the case of $\ell$ = 1 baryons. The compatibility between this picture and that of resonances in meson-nucleon scattering is discussed in the light of the present results.

Jets are identified and their properties studied in center-of-mass energy $\sqrt{s}=7\mathrm{TeV}$ proton-proton collisions at the Large Hadron Collider using charged particles measured by the ATLAS inner detector. Events are selected using a minimum bias trigger, allowing jets at very low transverse momentum to be observed and their characteristics in the transition to high-momentum fully perturbative jets to be studied. Jets are reconstructed using the anti-$k_t$ algorithm applied to charged particles with two radius parameter choices, 0.4 and 0.6. An inclusive charged jet transverse momentum cross section measurement from 4 GeV to 100 GeV is shown for four ranges in rapidity extending to 1.9 and corrected to charged particle-level truth jets. The transverse momenta and longitudinal momentum fractions of charged particles within jets are measured, along with the charged particle multiplicity and the particle density as a function of radial distance from the jet axis. Comparison of the data with the theoretical models implemented in existing tunings of Monte Carlo event generators indicates reasonable overall agreement between data and Monte Carlo. These comparisons are sensitive to Monte Carlo parton showering, hadronization, and soft physics models.

The $B_s^0$ differential production cross section is measured as functions of the transverse momentum and rapidity in $pp$ collisions at $\sqrt{s}=7\mathrm{TeV}$, using the $B_s^0\to J/\psi \varphi$ decay, and compared with predictions based on perturbative QCD calculations at next-to-leading order. The data sample, collected by the CMS experiment at the LHC, corresponds to an integrated luminosity of $40{\mathrm{pb}}^{-1}$. The $B_s^0$ is reconstructed from the decays $J/\psi \to {\mu }^{+}{\mu }^{-}$ and $\varphi \to K^{+}{K}^{-}$. The integrated $B_s^0$ cross section times $B_s^0\to J/\psi \varphi$ branching fraction in the range $8<p_{\mathrm{T}}^B<50\mathrm{GeV}/c$ and $|y^B|<2.4$ is measured to be $6.9\pm 0.6\pm 0.6\mathrm{nb}$, where the first uncertainty is statistical and the second is systematic.

Wick’s theorem in the Schwinger-Perel-Keldysh closed-time-loop formalism is written in a form where the place of contractions is taken by the linear response function of the field. This result demonstrates that the physical information supplied by Wick’s theorem for operators is propagation of the free field in space and time.

Known results on two-dimensional quantum electrodynamics (${\mathrm{QED}}_2$) have been used to study the dependence of functional renormalization group equations on renormalization schemes and approximations applied for its bosonized version. It is demonstrated that the singularity of flow equations can be avoided in the optimized and power-law schemes for the bosonized model and the drawback of renormalization on bosonization is shown: it is indicated that renormalization of ${\mathrm{QED}}_2$ possibly requires interaction terms corresponding to higher frequency modes of its bosonized version.

In order to avoid known, long-standing problems with higher-spin interactions, the electromagnetic field is introduced “dynamically” by using a nonsingular, Lorentz-type transformation, acting as adjoint representation on the Poincaré algebra of the free theory. In doing so, Lorentz transformation and local gauge transformation are placed on the same foundations, leading to the phase transition as a consequence of the gauge transformation. The procedure is exemplified in the case of plane waves for the Dirac-type equation and the Rarita-Schwinger equation.

It is shown for a class of random, time-independent, square-integrable, three-dimensional magnetic fields that the one-loop effective fermion action of four-dimensional QED increases faster than a quadratic in $\mathbf{B}$ in the strong coupling limit. The limit is universal. The result relies on the paramagnetism of charged spin-$1/2$ fermions and the diamagnetism of charged scalar bosons.

A black hole immersed in a rotating universe, described by the Gimon-Hashimoto solution, is tested on stability against scalar field perturbations. Unlike the previous studies on perturbations of this solution, which dealt only with the limit of slow universe rotation $j$, we managed to separate variables in the perturbation equation for the general case of arbitrary rotation. This leads to qualitatively different dynamics of perturbations, because the exact effective potential does not allow for Schwarzschild-like asymptotic of the wave function in the form of purely outgoing waves. The Dirichlet boundary conditions are allowed instead, which result in a totally different spectrum of asymptotically Gödel black holes: the spectrum of quasinormal frequencies is similar to the one of asymptotically anti-de Sitter black holes. At large and intermediate overtones $N$, the spectrum is equidistant in $N$. In the limit of small black holes, quasinormal modes (QNMs) approach the normal modes of the empty Gödel space-time. There is no evidence of instability in the found frequencies, which supports the idea that the existence of closed timelike curves (CTCs) and the onset of instability correlate (if at all) not in a straightforward way.

We provide a simple transfer function that determines the effect of an early matter-dominated era on the gravitational-wave background and show that a large class of compactifications of superstring theory might be tested by observations of the gravitational-wave background from inflation. For large enough reheating temperatures $\gtrsim {10}^9\mathrm{GeV}$, the test applies to all models containing at least one scalar with mass $\lesssim {10}^{12}\mathrm{GeV}$ that acquires a large initial oscillation amplitude after inflation and has only gravitational interaction strength, i.e., a field with the typical properties of a modulus.

We discuss a scheme based on Ehrenfest-like equations to exhibit and classify transitions between two phases (with “smaller” and “larger” masses) of Kerr-AdS black holes. We show that for fixed angular velocity this phase transition is of second order as both Ehrenfest’s equations are satisfied. Finally, we make a close connection of the results found from this analysis with those obtained from the thermodynamic state space geometry approach.

In this paper, we explore the ability of future low-frequency gravitational wave detectors to measure the spin of stellar mass and intermediate mass black holes (IMBHs) that inspiral into spinning supermassive black holes (SMBHs). We describe a kludge waveform model based on the equations of motion derived by Saijo et al. [M. Saijo, K. Maeda, M. Shibata, and Y. Mino, Phys. Rev. D 58, 064005 (1998).] for spinning black hole (BH) binaries, augmented with spin-orbit and spin-spin couplings taken from perturbative and post-Newtonian (PN) calculations, and the associated conservative self-force corrections, derived by comparison to PN results. We model the inspiral phase using accurate fluxes, which include perturbative corrections for the spin of the inspiralling body, spin-spin couplings and higher-order fits to solutions of the Teukolsky equation. We present results of Monte Carlo simulations of parameter-estimation errors, computed using the Fisher Matrix formalism, and also of the model errors that arise when we omit conservative corrections from the waveform template. We present results for the inspirals of spinning BHs with masses $\mu =10M_{\odot }$, ${10}^2{M}_{\odot }$, ${10}^3{M}_{\odot }$, $5\times {10}^3{M}_{\odot }$, into SMBHs of specific spin parameter $q=0.9$, and mass $M={10}^6{M}_{\odot }$. The analysis shows that for intermediate-mass-ratio inspirals, e.g., a source $5\times {10}^3{M}_{\odot }+{10}^6{M}_{\odot }$ observed with a signal-to-noise ratio of 1000, observations made with LISA will be able to determine the inspiralling BH mass, the central SMBH mass, the SMBH spin magnitude, and the magnitude of the spin of the inspiralling BH to within fractional errors of $\sim {10}^{-3}$, ${10}^{-3}$, ${10}^{-4}$, 10%, respectively. We also expect to determine the location of the source in the sky and the SMBH spin orientation to within $\sim {10}^{-4}$ steradians. However, for extreme-mass-ratio inspirals, e.g., a $10M_{\odot }+{10}^6{M}_{\odot }$ system observed with signal-to-noise ratio of 30, LISA will not be able to determine the spin magnitude of the inspiralling object, although the measurement of the other waveform parameters is not significantly degraded by the presence of spin. We also show that the model errors which arise from ignoring conservative corrections become significant for mass-ratios above $\sim {10}^{-4}$, but including these corrections up to second PN order may be sufficient to reduce these systematic errors to an acceptable level.

A quartic, self-interacting potential in the induced gravity framework is known to have a pure de Sitter attractor for the homogeneous mode. In order to obtain nonzero slow-roll parameters, we therefore study the quantum backreaction of the scalar and the tensor perturbations on such a homogeneous dynamics. The results are then compared with inflationary observables in order to constrain the parameters of the model.

It is well known that observing $CP$ violation in many-body decays could provide strong evidence for physics beyond the standard model. Many searches have been carried out; however, no $5\sigma$ evidence for $CP$ violation has yet been found in these types of decays. A novel model-independent method for observing $CP$ violation in many-body decays is presented in this paper. It is shown that the sensitivity of this method is significantly larger than those used to-date.

Matrix element $U_{\tau N}$ of sterile neutrino $N$ mixing with ${\nu }_{\tau }$ is the least constrained in the literature among the three $U_{\alpha N}$ ($\alpha =e$, $\mu$, $\tau$) mixing parameters characterizing the sterile neutrino phenomenology. We study the contribution of massive dominantly sterile neutrinos to purely leptonic $\tau$ decays and semileptonic decays of $\tau$ and $K$, $D$ mesons. We consider some decays allowed in the standard model as well as lepton flavor and lepton number violating decays forbidden in the standard model. From the existing experimental data on the branching ratios of these processes we derived new limits on $U_{\tau N}$ more stringent than the ones existing in the literature. These limits are extracted in a model independent way without any ad hoc assumptions on the relative size of the three different sterile neutrino mixing parameters.

The neutrino mixing angle ${\theta }_{13}$ is at the focus of current neutrino research. From a global analysis of the available oscillation data in a $3\nu$ framework, we previously reported [Phys. Rev. Lett. 101, 141801 (2008)] hints in favor of ${\theta }_{13}>0$ at the 90% C.L. Such hints are consistent with the recent indications of a ${\nu }_{\mu }\to {\nu }_e$ appearance in the T2K and MINOS long-baseline accelerator experiments. Our global analysis of all the available data currently provides $>3\sigma$ evidence for nonzero ${\theta }_{13}$, with $1\sigma$ ranges ${sin}^2{\theta }_{13}=0.021\pm 0.007$ or $0.025\pm 0.007$, depending on reactor neutrino flux systematics. Updated ranges are also reported for the other $3\nu$ oscillation parameters $(\delta m^2,{sin}^2{\theta }_{12})$ and $(\Delta m^2,{sin}^2{\theta }_{23})$.

We discuss the role of cumulants of net baryon number fluctuations in the analysis of critical behavior in QCD and the study of freeze-out conditions in heavy ion experiments. Through the comparison of the current set of measurements of higher order cumulants of net baryon number fluctuations with lattice QCD calculations and results from hadron resonance gas model we can learn to what extent freeze-out as, determined by such cumulants, occurs close to the QCD transition temperature and thus can probe critical behavior at small values of the baryon chemical potential. However, we provide indications that a recently performed comparison of lattice QCD results on cumulants with data from heavy ion experiments suffer from systematic as well as statistical uncertainties in the lattice QCD calculations, which makes such comparison at present not useful.