We make an estimate of the quadratic correction in the pressure of cold quark matter using gauge/string duality.

We revisit an old idea that gravity can be unified with Yang-Mills theory by enlarging the gauge group of gravity formulated as gauge theory. Our starting point is an action that describes a generally covariant gauge theory for a group $G$. The Minkowski background breaks the gauge group by selecting in it a preferred gravitational SU(2) subgroup. We expand the action around this background and find the spectrum of linearized theory to consist of the usual gravitons plus Yang-Mills fields charged under the centralizer of the SU(2) in $G$. In addition, there is a set of Higgs fields that are charged both under the gravitational and Yang-Mills subgroups. These fields are generically massive and interact with both gravity and the Yang-Mills sector in the standard way. The arising interaction of the Yang-Mills sector with gravity is also standard. Parameters such as the Yang-Mills coupling constant and Higgs mass arise from the potential function defining the theory. Both are realistic in the sense explained in the paper.

In a recent paper [arXiv:1001.0785], Verlinde has shown that the Newton gravity appears as an entropy force. In this paper we show how gravity appears as entropy force in Einstein’s equation of gravitational field in a general spherically symmetric spacetime. We mainly focus on the trapping horizon of the spacetime. We find that when matter fields are absent, the change of entropy associated with the trapping horizon indeed can be identified with an entropy force. When matter fields are present, we see that heat flux of matter fields also leads to the change of entropy. Applying arguments made by Verlinde and Smolin, respectively, to the trapping horizon, we find that the entropy force is given by the surface gravity of the horizon. The cases in the untrapped region of the spacetime are also discussed.

We study gravitational wave emission from the quasicircular, extreme mass ratio inspiral of compact objects of mass $m_0$ into massive objects of mass $M\gg m_0$ whose external metric is identical to the Schwarzschild metric, except for the absence of an event horizon. To be specific we consider one of the simplest realizations of such an object: a nonrotating thin-shell gravastar. The power radiated in gravitational waves during the inspiral shows distinctive peaks corresponding to the excitation of the polar oscillation modes of the gravastar. For ultracompact gravastars the frequency of these peaks depends mildly on the gravastar compactness. For masses $M\sim {10}^6{M}_{\odot }$ the peaks typically lie within the optimal sensitivity bandwidth of the Laser Interferometer Space Antenna, potentially providing a unique signature of the horizonless nature of the central object. For relatively modest values of the gravastar compactness the radiated power has even more peculiar features, carrying the signature of the microscopic properties of the physical surface replacing the event horizon.

Starting from pure multidimensional gravity with curvature-nonlinear terms but no matter fields in the initial action, we obtain a cosmological model with two effective scalar fields related to the size of two extra factor spaces. The model includes both an early inflationary stage and that of modern accelerated expansion and satisfies the observational data. There are no small parameters; the effective inflaton mass depends on the initial conditions which explain its small value as compared to the Planck mass. At the modern stage, the size of extra dimensions slowly increases, therefore this model predicts drastic changes in the physical laws of our Universe in the remote future.

We investigate the $Q$-ball formation in the thermal logarithmic potential by means of the lattice simulation, and reconfirm qualitatively the relation between $Q$-ball charge and the amplitude of the Affleck-Dine field at the onset of its oscillation. We find time dependence of some properties of the $Q$ ball, such as its size and the field value at its center. Since the thermal logarithmic potential decreases as the temperature falls down, the gravity-mediation potential will affect the properties of the $Q$ ball. Even in the case when the gravity-mediation potential alone does not allow $Q$-ball solution, we find the transformation from the thick-wall type of the $Q$ ball to the thin-wall type, contrary to the naive expectation that the $Q$ balls will be destroyed immediately when the gravity-mediation potential becomes dominant at the center of the $Q$ ball.

In this paper, we compare the relative sensitivities of gamma-ray and neutrino observations to the dark matter annihilation cross section in leptophilic models such as have been designed to explain PAMELA data. We investigate whether the high energy neutrino telescope IceCube will be competitive with current and upcoming searches by gamma-ray telescopes, such as the Atmospheric Çerenkov Telescopes (H.E.S.S., VERITAS, and MAGIC), or the Fermi Gamma-Ray Space Telescope, in detecting or constraining dark matter particles annihilating in dwarf spheroidal galaxies. We find that after 10 years of observation of the most promising nearby dwarfs, IceCube will have sensitivity comparable to the current sensitivity of gamma-ray telescopes only for very heavy ($m_X\gtrsim 7\mathrm{TeV}$) or relatively light ($m_X\lesssim 200\mathrm{GeV}$) dark matter particles which annihilate primarily to ${\mu }^{+}{\mu }^{-}$. If dark matter particles annihilate primarily to ${\tau }^{+}{\tau }^{-}$, IceCube will have superior sensitivity only for dark matter particle masses below the 200 GeV threshold of current Atmospheric Çerenkov Telescopes. If dark matter annihilations proceed directly to neutrino-antineutrino pairs a substantial fraction of the time, IceCube will be competitive with gamma-ray telescopes for a much wider range of dark matter masses.

We compute the reduced cosmic shear up to second order in the gravitational potential without relying on the small-angle or thin-lens approximation. This is obtained by solving the Sachs equation which describes the deformation of the infinitesimal cross section of a light bundle in the optical limit, and maps galaxy intrinsic shapes into their angular images. The calculation is done in the Poisson gauge without a specific matter content, including vector and tensor perturbations generated at second order and taking account of the inhomogeneities of a fixed redshift source plane. Our final result is expressed in terms of spin-2 operators on the sphere and is valid on the full sky. Beside the well-known lens-lens and Born corrections that dominate on small angular scales, we find new nonlinear couplings. These are a purely general relativistic intrinsic contribution, a coupling between the gravitational potential at the source with the lens, couplings between the time delay with the lens and between two photon deflections, as well as nonlinear couplings due to the second-order vector and tensor components. The inhomogeneity in the redshift of the source induces a coupling between the photon redshift with the lens. All these corrections become important on large angular scales and should thus be included when computing higher-order observables such as the bispectrum, in full or partially full-sky surveys.

A fully gapped state of matter, whether insulator or superconductor, can be asked if it is topologically trivial or nontrivial. Here we investigate topological properties of superconducting Dirac fermions in 3D having a color superconductor as an application. In the chiral limit, when the pairing gap is parity even, the right-handed and left-handed sectors of the free space Hamiltonian have nontrivial topological charges with opposite signs. Accordingly, a vortex line in the superconductor supports localized gapless right-handed and left-handed fermions with the dispersion relations $E=\pm v{p}_z$ ($v$ is a parameter dependent velocity) and thus propagating in opposite directions along the vortex line. However, the presence of the fermion mass immediately opens up a mass gap for such localized fermions and the dispersion relations become $E=\pm v\sqrt{m^2+p_z^2}$. When the pairing gap is parity odd, the situation is qualitatively different. The right-handed and left-handed sectors of the free space Hamiltonian in the chiral limit have nontrivial topological charges with the same sign and therefore the presence of the small fermion mass does not open up a mass gap for the fermions localized around the vortex line. When the fermion mass is increased further, there is a topological phase transition at $m=\sqrt{{\mu }^2+{\Delta }^2}$ and the localized gapless fermions disappear. We also elucidate the existence of gapless surface fermions localized at a boundary when two phases with different topological charges are connected. A part of our results is relevant to the color superconductivity of quarks.

We study the $W/Z$ pair production via two-photon exchange at the LHC and give the sensitivities on trilinear and quartic gauge anomalous couplings between photons and $W/Z$ bosons for an integrated luminosity of 30 and $200{\mathrm{fb}}^{-1}$. For simplicity and to obtain lower backgrounds, only the leptonic decays of the electroweak bosons are considered.

The ${\overline{\nu }}_{\mathrm{e}}-{\mathrm{e}}^{-}$ elastic scattering cross section was measured with a CsI(Tl) scintillating crystal array having a total mass of 187 kg. The detector was exposed to an average reactor ${\overline{\nu }}_{\mathrm{e}}$ flux of $6.4\times {10}^{12}{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$ at the Kuo-Sheng Nuclear Power Station. The experimental design, conceptual merits, detector hardware, data analysis, and background understanding of the experiment are presented. Using $29882/7369\mathrm{kg}$-days of Reactor ON/OFF data, the standard model (SM) electroweak interaction was probed at the squared 4-momentum transfer range of $Q^2\sim 3\times {10}^{-6}{\mathrm{GeV}}^2$. The ratio of experimental to SM cross sections of $\xi =[1.08\pm 0.21(\mathrm{stat})\pm 0.16(\mathrm{sys})]$ was measured. Constraints on the electroweak parameters ($g_V,g_A$) were placed, corresponding to a weak mixing angle measurement of ${sin}^2{\theta }_{\mathrm{W}}=0.251\pm 0.031(\mathrm{stat})\pm 0.024(\mathrm{sys})$. Destructive interference in the SM ${\overline{\nu }}_{\mathrm{e}}-\mathrm{e}$ process was verified. Bounds on anomalous neutrino electromagnetic properties were placed: neutrino magnetic moment at ${\mu }_{{\overline{\nu }}_{\mathrm{e}}}<2.2\times {10}^{-10}{\mu }_{\mathrm{B}}$ and the neutrino charge radius at $-2.1\times {10}^{-32}{\mathrm{cm}}^2<⟨{\mathrm{r}}_{{\overline{\nu }}_{\mathrm{e}}}^2⟩<3.3\times {10}^{-32}{\mathrm{cm}}^2$, both at 90% confidence level.

We study the critical boundary on the quark-mass plane associated with the chiral phase transition in QCD at finite temperature. We point out that the critical boundaries obtained from the lattice QCD simulation and the chiral effective model are significantly different; in the (Polyakov-loop coupled) Nambu–Jona-Lasinio (NJL) model we find that the critical mass is about 1 order of magnitude smaller than the value reported in the lattice QCD case. The lattice QCD study yields smaller critical mass in the continuum limit along the temporal direction. To investigate the temporal UV-cutoff effects quantitatively, we consider the (P)NJL model with only finite Matsubara summation $N_{\tau }$. We confirm that the critical mass in such a UV-tamed NJL model becomes larger with decreasing $N_{\tau }$, which demonstrates a correct tendency to explain the difference between the lattice QCD and chiral model results.

Mirror dark matter offers a framework to explain the existing dark matter direct detection experiments, including the impressive DAMA signal. Here, we examine the implications of mirror dark matter for experiments like CDMS II/Ge and XENON10 which feature higher recoil energy threshold than the DAMA NaI experiments. We show that the two events seen in the CDMS II/Ge experiment are consistent with the interactions of the anticipated heavy $\sim F{e}^{\prime }$ component. This interpretation of the CDMS II/Ge events is a natural one given that (a) mirror dark matter predicts an event rate which is sharply falling with respect to recoil energy and (b) that the two observed events are in the low energy region near threshold. Importantly, this interpretation of the CDMS II events can be checked by ongoing and future experiments, and we hereby predict that the bulk of the events will be in the $E_R\le 18\mathrm{keV}$ region.

We derive the equations describing a general static spherically symmetric configuration for the softly broken Hořava gravity introduced by A. Kehagias and K. Sfetsos with nonzero shift field and no-projectability condition. These represent “hedgehog” versions of black holes with radial “hair” arising from the shift field. For the case of the standard de Witt kinetic term ($\lambda =1$) there is an infinity of solutions that exhibit a deformed version of reparametrization invariance away from the general relativistic limit. Special solutions also arise in the anisotropic conformal point $\lambda =\frac{1}{3}$. Moreover we obtain an implicit general expression for the solutions with $N_r=0$ and generic $\lambda$. In this context we study the presence of horizons for standard matter and the related Hawking temperature, generalizing the corresponding relations in the usual static spherically symmetric case.

Merging supermassive black hole–black hole binaries produced in galaxy mergers are promising sources of detectable gravitational waves. If such a merger takes place in a gaseous environment, there is a possibility of a simultaneous detection of electromagnetic and gravitational radiation, as the stirring, shock heating, and accretion of the gas may produce variability and enhancements in the electromagnetic flux. Such a simultaneous detection can provide a wealth of opportunities to study gravitational physics, accretion physics, and cosmology. We investigate this scenario by performing fully general-relativistic, hydrodynamic simulations of merging, equal-mass, nonspinning black hole–black hole binaries embedded in gas clouds. We evolve the metric using the Baumgarte-Shapiro-Shibata-Nakamura formulation with standard moving puncture gauge conditions and handle the hydrodynamics via a high-resolution shock-capturing scheme. We consider both “binary Bondi accretion” in which the binary is at rest relative to the ambient gas cloud, as well as “binary Bondi-Hoyle-Lyttleton accretion” in which the binary moves relative to the gas cloud. The gas cloud is assumed to be homogeneous far from the binary and governed by a $\Gamma$-law equation of state. We vary $\Gamma$ between $4/3$ and $5/3$. For each simulation, we compute the gas flow and accretion rate and estimate the electromagnetic luminosity due to bremsstrahlung and synchrotron emission. We find evidence for significant enhancements in both the accretion rate and luminosity over values for a single black hole of the same mass as the binary. We estimate that this luminosity enhancement should be detectable by the Large Synoptic Survey Telescope for a ${10}^6{M}_{\odot }$ binary in a hot gas cloud of density $n\sim 10{\mathrm{cm}}^{-3}$ and temperature $T\sim {10}^6\mathrm{K}$ at $z=1$, reaching a maximum of $L\sim 3\times {10}^{43}\mathrm{erg}{\mathrm{s}}^{-1}$, with the emission peaking in the visible band, and lasting for $\sim 1$ hour.

In addition to producing loud gravitational waves, the dynamics of a binary black hole system could induce emission of electromagnetic radiation by affecting the behavior of plasmas and electromagnetic fields in their vicinity. We study how the electromagnetic fields are affected by a pair of orbiting black holes through the merger. In particular, we show how the binary’s dynamics induce a variability in possible electromagnetically induced emissions as well as an enhancement of electromagnetic fields during the late-merge and merger epochs. These time dependent features will likely leave their imprint in processes generating detectable emissions and can be exploited in the detection of electromagnetic counterparts of gravitational waves.

In order to examine the rotational effect around neutron star in tensor-vector-scalar (TeVeS) theory, we consider the slowly rotating relativistic stars with a uniform angular velocity. As a result, we find that similar to the case in general relativity (GR), the angular momentum is proportional to the angular velocity. Additionally, as the value of coupling constant $K$ becomes higher, the frame dragging in TeVeS becomes quite different distribution from that in GR, where we can also see the deviation even in the interior of star. While with smaller value of $K$, although the frame dragging approaches to that expected in GR, the induced vector field due to the rotation does not vanish and still exists. Thus, through the observations associated with relativistic object, one could be possible to distinguish the gravitational theory in strong field regime even in the case that the value of coupling constant $K$ is quite small.

Analytic formulas of Minkowski functionals in two-dimensional random fields are derived, including effects of second-order non-Gaussianity in the presence of both the bispectrum and trispectrum. The set of formulas provides a promising method to constrain the primordial non-Gaussianity of the universe by temperature fluctuations in the cosmic microwave background radiation. In a case of local-type non-Gaussianity, the Minkowski functionals are analytically given by powers of quadratic and cubic parameters, $f_{\mathrm{NL}}$ and $g_{\mathrm{NL}}$ (and ${\tau }_{\mathrm{NL}}$). Our formulas are not restricted to this particular model, and applicable to a wide class of non-Gaussian models. The analytic formulas are compared to numerical evaluations from non-Gaussian realizations of temperature maps, showing very good agreement.

We study the finite supersymmetric loop corrections to fermion masses and mixing matrices in the generic MSSM. In this context the effects of non-decoupling chirally-enhanced self-energies are studied beyond leading order in perturbation theory. These NLO corrections are not only necessary for the renormalization of the CKM matrix to be unitary, they are also numerically important for the light fermion masses. Focusing on the trilinear $A$-terms with generic flavor-structure we derive very strong bounds on the chirality-changing mass insertions ${\delta }_{IJ}^{fLR,RL}$ by applying ’t Hooft’s naturalness criterion. In particular, the NLO corrections to the up quark mass allow us to constrain the unbounded element ${\delta }_{13}^{uRL}$ if at the same time ${\delta }_{13}^{uLR}$ is unequal to zero. Our result is important for single-top production at the LHC.

In the absence of low energy supersymmetry, we show that (a) the dark matter particle alone at the TeV scale can improve gauge coupling unification, raising the unification scale up to the lower bound imposed by proton decay, and (b) the dark matter stability can automatically follow from the grand unification symmetry. Within reasonably simple unified models, a unique candidate satisfying these two properties is singled out: a fermion isotriplet with zero hypercharge, member of a 45 (or larger) representation of $SO(10)$. We discuss the phenomenological signatures of this TeV scale fermion, which can be tested in direct and indirect future dark matter searches. The proton decay rate into $e^{+}{\pi }^0$ is predicted close to the present bound.