We study the Eguchi-Kawai reduction in the strong-coupling domain of gauge theories via the gravity dual of $\mathcal{N}=4$ super-Yang-Mills on ${\mathbb{R}}^3\times {\mathbb{S}}^1$. We show that $D$-branes geometrize volume independence in the center-symmetric vacuum and give supergravity predictions for the range of validity of reduced large-$N$ models at strong coupling.

The moduli space metric and its Kähler potential for well-separated non-Abelian vortices are obtained in $U(N)$ gauge theories with $N$ Higgs fields in the fundamental representation.

We study a modification of the Plebanski action for general relativity, which leads to a modified theory of gravity with 8 degrees of freedom. We show how the action can be recasted as a bimetric theory of gravity, and expanding around a biflat background we identify the 6 extra degrees of freedom with a second, massive graviton and a scalar mode.

We present the results of three-dimensional general relativistic hydrodynamic simulations of adiabatic and spherically symmetric accretion in Kerr space-time. We consider compact objects with spin parameter $|a_{*}|\le 1$ (black holes) and with $|a_{*}|>1$ (superspinars). Our full three-dimensional simulations confirm the formation of equatorial outflows for high values of $|a_{*}|$, as found in our previous work in 2.5 dimensions. We show that the critical value of $|a_{*}|$ determining the onset of powerful outflows depends mainly on the radius of the compact object. The phenomenon of equatorial outflows can hardly occur around a black hole and may thus be used to test the bound $|a_{*}|\le 1$ for astrophysical black hole candidates.

As a possible source of the single transverse-spin asymmetry, we study the contribution from purely gluonic correlation represented by the twist-3 “three-gluon correlation” functions in the transversely polarized nucleon. We first define a complete set of the relevant three-gluon correlation functions, and then derive its contribution to the twist-3 single-spin-dependent cross section for the $D$-meson production in semi-inclusive deep inelastic scattering, which is relevant to determine the three-gluon correlations. Our cross-section formula differs from the corresponding result in the literature, and the origin of the discrepancy is clarified.

In the framework of the $k_t$-factorization approach, the photon-associated production of ${\rm Y}$ mesons at the present-day LHC conditions is studied. The differential cross sections and polarization parameters are calculated in the “helicity” and Collins-Soper systems. Special attention is paid to the effect of experimental cuts that can dramatically change the visible lepton angular distributions.

We explore consequences of the recently discovered duality between color and kinematics, which states that kinematic numerators in a diagrammatic expansion of gauge-theory amplitudes can be arranged to satisfy Jacobi-like identities in one-to-one correspondence to the associated color factors. Using on-shell recursion relations, we give a field-theory proof showing that the duality implies that diagrammatic numerators in gravity are just the product of two corresponding gauge-theory numerators, as previously conjectured. These squaring relations express gravity amplitudes in terms of gauge-theory ingredients, and are a recasting of the Kawai, Lewellen, and Tye relations. Assuming that numerators of loop amplitudes can be arranged to satisfy the duality, our tree-level proof immediately carries over to loop level via the unitarity method. We then present a Yang-Mills Lagrangian whose diagrams through five points manifestly satisfy the duality between color and kinematics. The existence of such Lagrangians suggests that the duality also extends to loop amplitudes, as confirmed at two and three loops in a concurrent paper. By “squaring” the novel Yang-Mills Lagrangian we immediately obtain its gravity counterpart. We outline the general structure of these Lagrangians for higher points. We also write down various new representations of gauge-theory and gravity amplitudes that follow from the duality between color and kinematics.

The Maxwell algebra is a noncentral extension of the Poincaré algebra, in which the momentum generators no longer commute, but satisfy $[P_{\mu },P_{\nu }]=Z_{\mu \nu }$. The charges $Z_{\mu \nu }$ commute with the momenta, and transform tensorially under the action of the angular momentum generators. If one constructs an action for a massive particle, invariant under these symmetries, one finds that it satisfies the equations of motion of a charged particle interacting with a constant electromagnetic field via the Lorentz force. In this paper, we explore the analogous constructions where one starts instead with the ISim subalgebra of Poincaré, this being the symmetry algebra of very special relativity. It admits an analogous noncentral extension, and we find that a particle action invariant under this Maxwell-Sim algebra again describes a particle subject to the ordinary Lorentz force. One can also deform the ISim algebra to ${\mathrm{DISim}}_b$, where $b$ is a nontrivial dimensionless parameter. We find that the motion described by an action invariant under the corresponding Maxwell-DISim algebra is that of a particle interacting via a Finslerian modification of the Lorentz force. In an appendix is it shown that the ${\mathrm{DISim}}_b$ algebra is isomorphic to the extended Schrödinger algebra with its standard deformation parameter $z$, when $b=\frac{1}{1-z}$.

By using the Britto-Cachazo-Feng-Witten recursion relation of $\mathcal{N}=4$ super Yang-Mills theory, we proved the color reflection, $U(1)$ decoupling, Kleiss-Kuijf and Bern-Carrasco-Johansson relations for color-ordered amplitudes of $\mathcal{N}=4$ super Yang-Mills theory. This proof verified the conjectured Bern-Carrasco-Johansson relations of matter fields. The proof depended only on general properties of superamplitudes. We showed also that the color reflection relation and $U(1)$-decoupling relation are special cases of Kleiss-Kuijf relations.

The thermodynamics of Schwarzschild black holes within spherical isothermal cavities in anti–de Sitter (AdS) space is studied for arbitrary dimensions in the semiclassical approximation of the Euclidean path integral of quantum gravity. For such boundary conditions, known classical solutions are a hot AdS and two or no Schwarzschild-AdS depending on whether or not the wall-temperature of the cavity is above or below a minimum value. Earlier work in four dimensions with such boundary conditions showed that the larger and smaller holes have positive and negative specific heats and hence are locally thermodynamically stable and unstable, respectively. The standard area-law of entropy was known to hold too. We derive the area-law for arbitrary dimensions and show that qualitative behavior of local stability remains the same. Then using a careful analysis of the associated Dirichlet boundary-value problem we address global issues. We find that for wall-temperatures above a critical value a phase transition takes hot AdS to the larger Schwarzschild-AdS. The larger hole thus can be globally thermodynamically stable. We find that the smaller the cavity the higher the critical temperature for phase transition is and it always remains above the minimum temperature needed for the classical existence of the holes in that cavity. In the infinite limit of cavity this picture reduces to that considered by Hawking and Page. All these hold for arbitrary dimensions, however the case of five dimensions turns out to be special in that the Dirichlet problem can be solved exactly giving exact analytic expressions for the black-hole masses as functions of boundary variables (cavity-radius and temperature). This makes it possible to compute the on-shell Euclidean action as a function of boundary variables too from which other quantities of interest can be evaluated. In particular, we obtain the minimum temperature (for the holes to exist classically) and the critical temperature (for phase transition) as functions of the cavity-radius in five dimensions.

At early stages the dynamics of cosmic string networks is expected to be influenced by an excessive production of small loops at the scales of initial conditions $l_{\min }$. To understand the late time behavior we propose a very simple analytical model of strings with a nonscaling population of loops. The complicated nonlinear dynamics is described by only a single parameter $N\sim 2/(1-C(l_{\min }))$ where $C(l)$ is a correlation function of the string tangent vectors. The model predicts an appearance of two new length scales: the coherence length $\xi \sim t/N^2$ and the cross-correlation length $\chi \sim t/N$. At the onset of evolution $N\sim 10$ and at late times $N$ is expected to grow logarithmically due to cosmological stretching and emission of small loops. The very late time evolution might be modified further when the gravitational back-reaction scale grows larger than $l_{\min }$.

We consider the presence and evolution of primordial density perturbations in a cosmological model based on a simple ansatz which captures—by providing a set of effective gravitational field equations—the strength of the enhanced quantum loop effects that can arise during inflation. After deriving the general equations that perturbations obey, we concentrate on scalar perturbations and show that their evolution is quite different than that of conventional inflationary models but still phenomenologically acceptable. The main reason for this novel evolution is the presence of an oscillating regime after the end of inflation which makes all superhorizon scalar modes oscillate. The same reason allows for a natural and very fast reheating mechanism for the Universe.

The Milky Way’s dark matter halo is thought to contain large numbers of smaller subhalos. These objects can contain very high densities of dark matter and produce potentially observable fluxes of gamma rays. In this article, we study the gamma ray sources in the Fermi Gamma Ray Space Telescope’s recently published First Source Catalog and attempt to determine whether this catalog might contain a population of dark matter subhalos. We find that, while as many as approximately 20–60 of the catalog’s unidentified sources could plausibly be dark matter subhalos, such a population cannot be clearly identified as such at this time. From the properties of the sources in the First Source Catalog, we derive limits on the dark matter’s annihilation cross section that are comparably stringent to those derived from recent observations of dwarf spheroidal galaxies.

It is natural to assume a parity-neutral Universe and accordingly no particular parity preference in the cosmic microwave background sky. However, our investigation based on the WMAP 7-year power spectrum shows there exists a large-scale odd-parity preference with high statistical significance. We also find that the odd-parity preference in WMAP7 data is slightly higher than earlier releases. We have investigated possible origins, and ruled out various noncosmological origins. We also find that the primordial origin requires $|\mathrm{Re}[\Phi (\mathbf{k})]|\ll |\mathrm{Im}[\Phi (\mathbf{k})]|$ for $k\lesssim 22/{\eta }_0$, where ${\eta }_0$ is the present conformal time. In other words, it requires translational invariance in the primordial Universe to be violated on scales larger than $4\mathrm{Gpc}$. The Planck surveyor, which possesses wide frequency coverage and systematics distinct from the WMAP, may allow us to resolve the mystery of the anomalous odd-parity preference. Furthermore, polarization maps of large-sky coverage will reduce degeneracy in cosmological origins.

We study the peculiar velocities of density peaks in the presence of primordial non-Gaussianity. Rare, high-density peaks in the initial density field can be identified with tracers such as galaxies and clusters in the evolved matter distribution. The distribution of relative velocities of peaks is derived in the large-scale limit using two different approaches based on a local biasing scheme. Both approaches agree, and show that halos still stream with the dark matter locally as well as statistically, i.e. they do not acquire a velocity bias. Nonetheless, even a moderate degree of (not necessarily local) non-Gaussianity induces a significant skewness ($\sim 0.1–0.2$) in the relative velocity distribution, making it a potentially interesting probe of non-Gaussianity on intermediate to large scales. We also study two-point correlations in redshift space. The well-known Kaiser formula is still a good approximation on large scales, if the Gaussian halo bias is replaced with its (scale-dependent) non-Gaussian generalization. However, there are additional terms not encompassed by this simple formula which become relevant on smaller scales ($k\gtrsim 0.01h/\mathrm{Mpc}$). Depending on the allowed level of non-Gaussianity, these could be of relevance for future large spectroscopic surveys.

Under the assumption of classical conformal invariance, we study the Coleman-Weinberg symmetry breaking mechanism in the minimal left-right symmetric model. This model is attractive as it provides a natural framework for small neutrino masses and the restoration of parity as a good symmetry of nature. We find that, in a large fraction of the parameter space, the parity symmetry is maximally broken by quantum corrections in the Coleman-Weinberg potential, which are a consequence of the conformal anomaly. As the left-right symmetry breaking scale is connected to the Planck scale through the logarithmic running of the dimensionless couplings of the scalar potential, a large separation of the two scales can be dynamically generated. The symmetry breaking dynamics of the model was studied using a renormalization group analysis. Electroweak symmetry breaking is triggered by the breakdown of left-right symmetry, and the left-right breaking scale is therefore expected in the few-TeV range. The phenomenological implications of the symmetry breaking mechanism are discussed.

The electric dipole moment (EDM) of the top quark is calculated in a model with a vector like multiplet which mixes with the third generation in an extension of the minimal supersymmetric standard model. Such mixings allow for new $CP$ violating phases. Including these new $CP$ phases, the EDM of the top in this class of models is computed. The top EDM arises from loops involving the exchange of the W, the Z as well as from the exchange involving the charginos, the neutralinos, the gluino, and the vector like multiplet and their superpartners. The analysis of the EDM of the top is more complicated than for the light quarks because the mass of the external fermion, in this case the top quark mass cannot be ignored relative to the masses inside the loops. A numerical analysis is presented and it is shown that the top EDM could be close to ${10}^{-19}\mathrm{ecm}$ consistent with the current limits on the EDM of the electron, the neutron and on atomic EDMs. A top EDM of size ${10}^{-19}\mathrm{ecm}$ could be accessible in collider experiments such as the International Linear Collider.

We provide quantitative predictions for the rapidity, centrality and energy dependencies of inclusive charged-hadron productions for the forthcoming LHC measurements in nucleus-nucleus collisions based on the idea of gluon saturation in the color-glass condensate framework. Our formulation gives very good descriptions of the first data from the LHC for the inclusive charged-hadron production in proton-proton collisions, the deep inelastic scattering at the Hadron-Elektron-Ring-Anlage at small Bjorken $x$, and the hadron multiplicities in nucleus-nucleus collisions at the Relativistic Heavy Ion Collider.