Within a perturbative cosmological regime of loop quantum gravity corrections to effective constraints are computed. This takes into account all inhomogeneous degrees of freedom relevant for scalar metric modes around flat space and results in explicit expressions for modified coefficients and of higher order terms. It also illustrates the role of different scales determining the relative magnitude of corrections. Our results demonstrate that loop quantum gravity has the correct classical limit, at least in its sector of cosmological perturbations around flat space, in the sense of perturbative effective theory.

We calculate the gravitational self-force acting on a pointlike particle of mass $\mu$, set in a circular geodesic orbit around a Schwarzschild black hole. Our calculation is done in the Lorenz gauge: For given orbital radius, we first solve directly for the Lorenz-gauge metric perturbation using numerical evolution in the time domain; we then compute the (finite) backreaction force from each of the multipole modes of the perturbation; finally, we apply the “mode-sum” method to obtain the total, physical self-force. The temporal component of the self-force (which is gauge invariant) describes the dissipation of orbital energy through gravitational radiation. Our results for this component are consistent, to within the computational accuracy, with the total flux of gravitational-wave energy radiated to infinity and through the event horizon. The radial component of the self-force (which is gauge dependent) is calculated here for the first time. It describes a conservative shift in the orbital parameters away from their geodesic values. We thus obtain the $O(\mu )$ correction to the specific energy and angular momentum parameters (in the Lorenz gauge), as well as the $O(\mu )$ shift in the orbital frequency (which is gauge invariant).

We work on some general extensions of the formalism for theories which preserve the relativity of inertial frames with a nonlinear action of the Lorentz transformations on momentum space. Relativistic particle models invariant under the corresponding deformed symmetries are presented with particular emphasis on deformed dilatation transformations. The algebraic transformations relating the deformed symmetries with the usual (undeformed) ones are provided in order to preserve the Lorentz algebra. Two distinct cases are considered: a deformed dilatation transformation with a spacelike preferred direction and a very special relativity embedding with a lightlike preferred direction. In both analysis we consider the possibility of introducing quantum deformations of the corresponding symmetries such that the spacetime coordinates can be reconstructed and the particular form of the real space-momentum commutator remains covariant. Eventually feasible experiments, for which the nonlinear Lorentz dilatation effects here pointed out may be detectable, are suggested.

We prove that the AdS/CFT calculation of 1-point functions can be drastically simplified by using variational arguments. We give a simple proof, valid for any theory that can be derived from a Lagrangian, that the large radius divergencies in 1-point functions can always be renormalized away (at least in the semiclassical approximation). The renormalized 1-point functions then follow by a simple variational problem involving only finite quantities. Several examples, a massive scalar, gravity, and renormalization flows, are discussed. Our results are general and can thus be used for dualities beyond AdS/CFT.

We present a method for simulating relativistic and nonrelativistic scalar field theories at finite density, with matter transforming in the fundamental representation of the global symmetry group $O(N)$. The method avoids the problem of complex probability weights which is present in conventional path integral Monte Carlo algorithms. To verify our approach, we simulate the free and interacting relativistic $U(1)\simeq O(2)$ theory in $2+1$ dimensions. We compute the two-point correlation function and charge density as a function of chemical potential in the free theory. At weak $|\varphi {|}^4$ coupling and zero temperature we map the $m^2\mathrm{\text{−}}\mu$ phase diagram and compare our numerical results with perturbative calculations. Finally, we compute properties of the $T\mathrm{\text{−}}\mu$ phase diagram in the vicinity of the phase transition and at bare self-couplings large compared to the temperature and chemical potential.

We consider predictions for structure formation from modifications to general relativity in which the Einstein-Hilbert action is replaced by a general function of the Ricci scalar. We work without fixing a gauge, as well as in explicit popular coordinate choices, appropriate for the modification of existing cosmological code. We present the framework in a comprehensive and practical form that can be directly compared to standard perturbation analyses. By considering the full evolution equations, we resolve perceived instabilities previously suggested, and instead find a suppression of perturbations. This result presents significant challenges for agreement with current cosmological structure formation observations. The findings apply to a broad range of forms of $f(R)$ for which the modification becomes important at low curvatures, disfavoring them in comparison with the $\Lambda \mathrm{CDM}$ scenario. As such, these results provide a powerful method to rule out a wide class of modified gravity models aimed at providing an alternative explanation to the dark energy problem.

The equations describing nonradial adiabatic oscillations of differentially rotating relativistic stars are derived in relativistic slow rotation approximation. The differentially rotating configuration is described by a perturbative version of the relativistic $j$-constant rotation law. Focusing on the oscillation properties of the stellar fluid, the adiabatic nonradial perturbations are studied in the Cowling approximation with a system of five partial differential equations. In these equations, differential rotation introduces new coupling terms between the perturbative quantities with respect to the uniformly rotating stars. In particular, we investigate the axisymmetric and barotropic oscillations and compare their spectral properties with those obtained in nonlinear hydrodynamical studies. The perturbative description of the differentially rotating background and the oscillation spectrum agree within a few percent with those of the nonlinear studies.

We show that the $S^1$-rotating black rings can be superposed by the solution-generating technique. We analyze the black diring solution for the simplest case of multiple rings. There exists an equilibrium black diring where the conical singularities are cured by the suitable choice of physical parameters. Also there are infinite numbers of black dirings with the same mass and angular momentum. These dirings can have two different continuous limits of single black rings. Therefore, we can transform the fat black ring to the thin ring with the same mass and angular momentum by way of the diring solutions.

We explore the possibility that the observed baryon asymmetry of the Universe is the result of an earlier phase transition in which an extended gauge sector breaks down into the $SU(3{)}_C\times SU(2{)}_L\times U(1{)}_Y$ of the standard model. Our proto-typical example is the topflavor model, in which there is a separate $SU(2{)}_1$ for the third generation from the $SU(2{)}_2$ felt by the first two generations. We show that the breakdown of $SU(2{)}_1\times SU(2{)}_2\to SU(2{)}_L$ results in lepton number being asymmetrically distributed throughout the three families, and provided the SM electroweak phase transition is not strongly first order, results in a nonzero baryon number, which for parameter choices that can be explored at the LHC may explain the observed baryon asymmetry.

We make a systematic study of the cosmological dynamics for a number of $f(R)$ gravity theories in Palatini formalism, using phase space analysis as well as numerical simulations. Considering homogeneous and isotropic models, we find a number of interesting results: (i) models based on theories of the type (a) $f(R)=R-\beta /R^n$ and (b) $f(R)=R+\alpha \ln R-\beta$, unlike the metric formalism, are capable of producing the sequence of radiation-dominated, matter-dominated, and de Sitter periods, and (ii) models based on theories of the type (c) $f(R)=R+\alpha R^m-\beta /R^n$ can produce early as well as late accelerating phases but an early inflationary epoch does not seem to be compatible with the presence of a subsequent radiation-dominated era. Thus, for the classes of models considered here, we have been unable to find the sequence of all four dynamical epochs required to account for the complete cosmological dynamics, even though three out of four phases are possible. We also place observational constraints on these models using the recently released supernovae data by the Supernova Legacy Survey as well as the baryon acoustic oscillation peak in the Sloan Digital Sky Survey luminous red galaxy sample and the cosmic microwave background shift parameter. The best-fit values are found to be $n=0.027$, $\beta =4.63$ for the models based on (a) and $\alpha =0.11$, $\beta =4.62$ for the models based on (b), neither of which are significantly preferred over the $\Lambda \mathrm{CDM}$ model. Moreover, the logarithmic term alone is not capable of explaining the late acceleration. The models based on (c) are also consistent with the data with suitable choices of their parameters. We also find that some of the models for which the radiation-dominated epoch is absent prior to the matter-dominated era also fit the data. The reason for this apparent contradiction is that the combination of the data considered here does not place stringent enough constraints on the cosmological evolution prior to the decoupling epoch, which highlights the importance of our combined theoretical-observational approach to constrain models.

Observations of spiral galaxies strongly support a one-to-one analytical relation between the inferred gravity of dark matter at any radius and the enclosed baryonic mass. It is baffling that baryons manage to settle the dark matter gravitational potential in such a precise way, leaving no “messy” fingerprints of the merging events and “gastrophysical” feedbacks expected in the history of a galaxy in a concordance Universe. This correlation of gravity with baryonic mass can be interpreted from several nonstandard angles, especially as a modification of gravity called $\mathrm{T}e\mathrm{V}e\mathrm{S}$, in which no galactic dark matter is needed. In this theory, the baryon-gravity relation is captured by the dieletric-like function $\mu$ of modified Newtonian dynamics (MOND), controlling the transition from $1/r^2$ attraction in the strong gravity regime to $1/r$ attraction in the weak regime. Here, we study this $\mu$-function in detail. We investigate the observational constraints upon it from fitting galaxy rotation curves, unveiling the degeneracy between the stellar mass-to-light ratio and the $\mu$-function as well as the importance of the sharpness of transition from the strong to weak gravity regimes. We also numerically address the effects of nonspherical baryon geometry in the framework of nonlinear $\mathrm{T}e\mathrm{V}e\mathrm{S}$, and exhaustively examine how the $\mu$-function connects with the free function of that theory. In that regard, we exhibit the subtle effects and wide implications of renormalizing the gravitational constant. We finally present a discontinuity-free transition between quasistatic galaxies and the evolving Universe for the free function of $\mathrm{T}e\mathrm{V}e\mathrm{S}$, inevitably leading to a return to $1/r^2$ attraction at very low accelerations in isolated galaxies.

We show that dark matter emerging from late decays ($z\lesssim 1000$) produces a linear power spectrum identical to that of cold dark matter (CDM) on all observationally relevant scales ($\gtrsim 0.1\mathrm{Mpc}$), and simultaneously generates observable constant-density cores in small dark matter halos. We refer to this class of models as meta-cold dark matter ($m\mathrm{CDM}$), because it is born with nonrelativistic velocities from the decays of cold thermal relics. The constant-density cores are a result of the low phase-space density of $m\mathrm{CDM}$ at birth. Warm dark matter cannot produce similar size phase-space limited cores without saturating the $\mathrm{Ly}\alpha$ power spectrum bounds. Dark matter-dominated galaxy rotation curves and stellar velocity dispersion profiles may provide the best means to discriminate between $m\mathrm{CDM}$ and CDM. $m\mathrm{CDM}$ candidates are motivated by the particle spectrum of supersymmetric and extra dimensional extensions to the standard model of particle physics.

We investigate the color-spin locked phase of spin-one color-superconducting quark matter using a truncated Dyson-Schwinger equation for the quark propagator in Landau gauge. Starting from the most general parity conserving ansatz allowed by the color-spin locked symmetry, the Dyson-Schwinger equation is solved self-consistently and dispersion relations are discussed. We find that chiral symmetry is spontaneously broken due to terms which have previously been neglected. As a consequence, the excitation spectrum contains only gapped modes even for massless quarks. Moreover, at moderate chemical potentials the quasiparticle pairing gaps are several times larger than expected from extrapolated weak-coupling results.

We discuss double-diffractive (double-elastic) production of the ${\eta }^{\prime }$-meson in the $pp\to p{\eta }^{\prime }p$ reaction within the formalism of unintegrated gluon distribution functions (UGDF). We estimate also the contribution of ${\gamma }^{*}{\gamma }^{*}\to {\eta }^{\prime }$ fusion. The distributions in the Feynman $x_F$ (or rapidity), transferred four-momenta squared between initial and final protons $(t_1,t_2)$ and azimuthal angle difference between outgoing protons ($\Phi$) are calculated. The deviations from the ${sin}^2(\Phi )$ dependence predicted by one-step vector-vector-pseudoscalar coupling are quantified and discussed. The results are compared with the results of the WA102 collaboration at CERN. Most of the models of UGDF from the literature give a too small cross section as compared to the WA102 data and predict angular distribution in relative azimuthal angle strongly asymmetric with respect to $\pi /2$ in disagreement with the WA102 data. This points to a different mechanism at the WA102 energy. Predictions for RHIC, Tevatron and LHC are given. We find that the normalization, $t_{1,2}$ dependences as well as deviations from ${sin}^2(\Phi )$ of double-diffractive double-elastic cross section are extremely sensitive to the choice of UGDF. Possible implications for UGDFs are discussed.

In this article, we calculate the strong coupling constants of the $\rho NN$, $\rho \Sigma \Sigma$, and $\rho \Xi \Xi$ in the framework of the light-cone QCD sum rules approach. The strong coupling constants of the meson-baryon-baryon are the fundamental parameters in the one-boson exchange model which describes the baryon-baryon interactions successfully. The numerical values are in agreement with the existing calculations in part. The electric and magnetic $F/(F+D)$ ratios deviate from the prediction of the vector meson dominance theory; the $SU(3)$ symmetry breaking effects are very large.

Hadronic transitions of the ${\chi }_{cj}$ states have not been studied yet. We calculate the rate of the hadronic transition ${\chi }_{c1}\to {\eta }_c\pi \pi$ in the framework of QCD multipole expansion. We show that this process can be studied experimentally at the upgraded Beijing Spectrometer BES III and the Cornell CLEO-c.

We measure the branching ratios of the Cabibbo-suppressed decays ${\Lambda }_c^{+}\to \Lambda K^{+}$ and ${\Lambda }_c^{+}\to {\Sigma }^0{K}^{+}$ relative to the Cabibbo-favored decay modes ${\Lambda }_c^{+}\to \Lambda {\pi }^{+}$ and ${\Lambda }_c^{+}\to {\Sigma }^0{\pi }^{+}$ to be $0.044\pm 0.004(\mathrm{stat}.)\pm 0.003(\mathrm{syst}.)$ and $0.038\pm 0.005(\mathrm{stat}.)\pm 0.003(\mathrm{syst}.)$, respectively. We set an upper limit on the branching ratio at the 90% confidence level for ${\Lambda }_c^{+}\to \Lambda K^{+}{\pi }^{+}{\pi }^{-}$ of $4.1\times {10}^{-2}$ relative to ${\Lambda }_c^{+}\to \Lambda {\pi }^{+}$, and for ${\Lambda }_c^{+}\to {\Sigma }^0{K}^{+}{\pi }^{+}{\pi }^{-}$ of $2.0\times {10}^{-2}$ relative to ${\Lambda }_c^{+}\to {\Sigma }^0{\pi }^{+}$. We also measure the branching fraction for the Cabibbo-favored mode ${\Lambda }_c^{+}\to {\Sigma }^0{\pi }^{+}$ relative to ${\Lambda }_c^{+}\to \Lambda {\pi }^{+}$ to be $0.977\pm 0.015(\mathrm{stat}.)\pm 0.051(\mathrm{syst}.)$. This analysis was performed using a data sample with an integrated luminosity of $125{\mathrm{fb}}^{-1}$ collected by the $BABAR$ detector at the PEP-II asymmetric-energy $B$ factory at SLAC.

This is a reply to Rauscher [Phys. Rev. D 75, 068301 (2007)]. We studied heavy element production in the high baryon density region in the early universe [Phys. Rev. D 72, 123505 (2005)]. However, it is claimed by Rauscher [Phys. Rev. D 75, 068301 (2007)] that a small scale but high baryon density region contradicts observations for the light element abundance or, in order not to contradict the observations, the high density region must be so small that it cannot affect the present heavy element abundance. In this paper, we study big bang nucleosynthesis in the high baryon density region and show that in certain parameter spaces it is possible to produce enough of the heavy element without contradiction to cosmic microwave background and light element observations.

The work of Matsuura et al. [Phys. Rev. D 72, 123505 (2005)] claims that heavy nuclei could have been produced in a combined $p$- and $r$-process in very high baryon density regions of an inhomogeneous big bang. However, they do not account for observational constraints and previous studies which show that such high baryon density regions did not significantly contribute to big bang abundances.

In this paper, we study $O(2N)$-symmetric ${\varphi }^4$-theory at finite temperature and density using the two-particle irreducible $1/N$ expansion. As specific examples, we consider pion condensation at finite isospin chemical potential and kaon condensation at finite chemical potential for hypercharge and isospin charge. We calculate the phase diagrams and the quasiparticle masses for pions and kaons in the large-$N$ limit. It is shown that the effective potential and the gap equation can be renormalized by using local counterterms for the coupling constant and mass parameter, which are independent of temperature and chemical potentials.