We study the reactions $e^{+}{e}^{-}\to e^{+}{e}^{-}{\eta }^{(\prime )}$ in the single-tag mode and measure the $\gamma {\gamma }^{*}\to {\eta }^{(\prime )}$ transition form factors in the momentum-transfer range from 4 to $40{\mathrm{GeV}}^2$. The analysis is based on $469{\mathrm{fb}}^{-1}$ of integrated luminosity collected at PEP-II with the BABAR detector at $e^{+}{e}^{-}$ center-of-mass energies near 10.6 GeV.

We study the lightest masses in the fermionic sector of an anomalous $U(1{)}^{\prime }$ extension of the minimal supersymmetric standard model inspired by brane constructions. The lightest supersymmetric particle of this model is an extra weakly interacting massive particle which is shown to have a relic density satisfying WMAP data. This computation is carried out numerically after having adapted the DarkSUSY package to our case.

We calculate the cross sections of inclusive $J/\psi$ production in photoproduction and two-photon scattering, involving both direct and resolved photons, and in $e^{+}{e}^{-}$ annihilation at next-to-leading order within the factorization formalism of nonrelativistic quantum chromodynamics, including the full relativistic corrections due to the intermediate ${}^{1}S_0^{[8]}$, ${}^{3}S_1^{[8]}$, and ${}^{3}P_J^{[8]}$ color-octet states. Exploiting also our previous results on hadroproduction, we perform a combined fit of the respective color-octet long-distance matrix elements to all available high-quality data of inclusive $J/\psi$ production, from KEKB, LEP II, RHIC, HERA, the Tevatron, and the LHC, comprising a total of 194 data points from 26 data sets.

We investigate several holographic properties of charged black holes with $R{F}^2$ corrections, which originate from Kaluza-Klein reductions of five-dimensional Gauss-Bonnet gravity. We obtain the perturbative solution and discuss its thermodynamics. The DC conductivity is calculated via the effective action approach, and the corrections to the DC conductivity are also evaluated. Moreover, we calculate the shear viscosity $\eta$ and thermal conductivity ${\kappa }_T$, as well as two interesting ratios $\eta /s$ and ${\kappa }_T{\mu }^2/(\eta T)$. We find that both bounds conjectured in the literatures can be violated in the presence of the higher- order corrections $R{F}^2$.

The consequences of on-shell supersymmetry are studied for scattering amplitudes with massive particles in four dimensions. Using the massive version of the spinor-helicity formalism, the supersymmetry transformations relating products of on-shell states are derived directly from the on-shell supersymmetry algebra for any massive representation. Solutions to the resulting Ward identities can be constructed as functions on the on-shell superspaces that are obtained from the coherent-state method. In simple cases, it is shown that these superspaces allow one to construct explicitly supersymmetric scattering amplitudes. Supersymmetric on-shell recursion relations for tree-level superamplitudes with massive particles are introduced. As examples, simple supersymmetric amplitudes are constructed in Supersymmetric Quantum Chromodynamics (SQCD), the Abelian Higgs model, the Coulomb branch of $\mathcal{N}=4$, QCD with an effective Higgs-gluon coupling and for massive vector-boson currents.

In this paper we compute the quantity which is truly measured in a large galaxy survey. We take into account the effects coming from the fact that we actually observe galaxy redshifts and sky positions and not true spatial positions. Our calculations are done within linear perturbation theory for both the metric and the source velocities but they can be used for nonlinear matter power spectra. We shall see that the complications due to the fact that we only observe on our background light cone, and that we do not truly know the distance of the observed galaxy but only its redshift, not only cause an additional difficulty, but provide even more a new opportunity for future galaxy surveys.

We present an analytical solution for the effect of thermorefractive noise considering finite-sized cylindrical test masses. For crystalline materials at low temperatures, the effect of finite dimensions becomes important. The calculations are independently performed using the Fluctuation-Dissipation-Theorem and Langevin’s approach. Our results are applied to the input test mass of the current and future cryogenic gravitational wave detectors CLIO, LCGT, and ET and are compared to the respective standard quantum limit. For a substrate temperature of 10 K, we find that the thermorefractive noise amplitude of the silicon input test mass in ET is only a factor of 2 below the standard quantum limit for frequencies above 500 Hz. Thus, thermorefractive noise of the input test mass could become a severe limitation if one uses techniques to beat the standard quantum limit like, e.g., squeezing. In contrast, the effect of thermorefractive noise of the input test mass is negligible for CLIO and LCGT.

We present the first $3+1$ dimensional simulations of non-Abelian plasma instabilities in gauge-covariant Boltzmann-Vlasov equations for the QCD gauge group SU(3) as well as for SU(4) and SU(5). The real-time evolution of instabilities for a plasma with stationary momentum-space anisotropy is studied using a hard-loop effective theory that is discretized in the velocities of hard particles. We find that the numerically less expensive calculations using the group SU(2) essentially reproduce the nonperturbative dynamics of non-Abelian plasma instabilities with higher rank gauge groups provided the mass parameters of the corresponding hard-loop effective theories are the same. In particular, we find very similar spectra for the turbulent cascade that forms in the strong-field regime, which is associated with an approximately linear growth of energy in collective fields. The magnitude of the linear growth however turns out to increase with the number of colors.

We correct a mistake in the power radiated by a quark moving on a circular trajectory in weakly coupled $\mathcal{N}=4$ supersymmetric theory. The angular dependence of the time-averaged angular distribution of power is found to be identical at weak and strong coupling.

We propose that neutron emission from Cen A dominates the cosmic ray sky at the high end of the spectrum. Neutrons that decay generate proton diffusion fronts, whereas those that survive decay produce an angular spike in the direction of the source. We use recent data reported by the Pierre Auger Collaboration to normalize the injection spectrum and estimate the required luminosity in cosmic rays. We find that such a luminosity, $L_{\mathrm{CR}}\sim 5\times {10}^{40}\mathrm{erg}/\mathrm{s}$, is comfortably smaller than the bolometric luminosity of Cen A, $L_{\mathrm{bol}}\sim {10}^{43}\mathrm{erg}/\mathrm{s}$. We compute the incoming current flux density as viewed by an observer on Earth, and we show that the anisotropy amplitude is in agreement with data at the $1\sigma$ level. Regardless of the underlying source model, our results indicate that after a decade of data taking the Pierre Auger Observatory will be able to test our proposal.

Chiral gravity admits asymptotically ${\mathrm{AdS}}_3$ solutions that are not locally equivalent to ${\mathrm{AdS}}_3$; meaning that solutions do exist which, while obeying the strong boundary conditions usually imposed in general relativity, happen not to be Einstein spaces. In topologically massive gravity (TMG), the existence of non-Einstein solutions is particularly connected to the question about the role played by complex saddle points in the Euclidean path integral. Consequently, studying (the existence of) nonlocally ${\mathrm{AdS}}_3$ solutions to chiral gravity is relevant to understanding the quantum theory. Here, we discuss a special family of nonlocally ${\mathrm{AdS}}_3$ solutions to chiral gravity. In particular, we show that such solutions persist when one deforms the theory by adding the higher-curvature terms of the so-called new massive gravity. Moreover, the addition of higher-curvature terms to the gravity action introduces new nonlocally ${\mathrm{AdS}}_3$ solutions that have no analogues in TMG. Both stationary and time-dependent, axially symmetric solutions that asymptote ${\mathrm{AdS}}_3$ space without being locally equivalent to it appear. Defining the boundary stress tensor for the full theory, we show that these non-Einstein geometries have associated vanishing conserved charges.

The aim of this work is to study the holographic dual to the gauge theory with a nonzero gluon condensate. We check for the consistency of the holographic way of describing the condensate and calculate the expectation value of a small Wilson loop in the presence of the gluon condensate, thus obtaining the relevant coefficient in the operator product expansion of the small loop in different holographic models. We also study the effect of the condensate on the Gross-Ooguri phase transition in the correlator of two circular Wilson loops in parallel and concentric configurations. In the numerical study of the concentric case, we find that the phase transition changes its order when the size of the loops is of order of the gluon condensate. We report this change of the phase transition order to be a new effect in Wilson loop correlator.

We study the superpotential induced by Euclidean D3-brane instantons carrying instanton flux, with special emphasis on its significance for the stabilization of Kähler moduli and Neveu-Schwarz axions in type IIB orientifolds. Quite generally, once a chiral observable sector is included in the compactification, arising on intersecting D7-branes with world-volume flux, resulting charged instanton zero modes prevent a class of instantons from participating in moduli stabilization. We show that instanton flux on Euclidean D3-branes can remove these extra zero modes and help in reinstating full moduli stabilization within a geometric regime. We comment also on the $F$-theoretic description of this effect of alleviating the general tension between moduli stabilization and chirality. In addition, we propose an alternative solution to this problem based on dressing the instantons with charged matter fields, which is unique to $F$ theory and cannot be realized in the weak coupling limit.

Using the Fedosov theory of deformation quantization of an endomorphism bundle we construct several models of pure geometric, deformed vacuum gravity, corresponding to an arbitrary symplectic noncommutativity tensor. Deformations of Einstein-Hilbert and Palatini actions are investigated. Coordinate covariant field equations are derived up to the second order of the deformation parameter. For some models they are solved and explicit corrections to an arbitrary Ricci-flat metric are pointed out. The relation to the theory of the Seiberg-Witten map is also studied and the correspondence to the spacetime noncommutativity described by the Fedosov $*$-product of functions is explained.

In the in-out formalism we advance a method of the inverse scattering matrix for calculating effective actions in pure magnetic field backgrounds. The one-loop effective actions are found in a localized magnetic field of Sauter type and approximately in a general magnetic field by applying the uniform semiclassical approximation. The effective actions exhibit the electromagnetic duality between a constant electric field and a constant magnetic field and between $E(x)=E{\mathrm{sech}}^2(x/L)$ and $B(x)=B{\mathrm{sech}}^2(x/L)$.

In a $U(1{)}_{\star }$-noncommutative gauge field theory we extend the Seiberg-Witten map to include the (gauge-invariance-violating) external current and formulate—to the first order in the noncommutative parameter–gauge-covariant classical field equations. We find solutions to these equations in the vacuum and in an external magnetic field, when the 4-current is a static electric charge of a finite size $a$, restricted from below by the elementary length. We impose extra boundary conditions, which we use to rule out all singularities, $1/r$ included, from the solutions. The static charge proves to be a magnetic dipole, with its magnetic moment being inversely proportional to its size $a$. The external magnetic field modifies the long-range Coulomb field and some electromagnetic form factors. We also analyze the ambiguity in the Seiberg-Witten map and show that at least to the order studied here it is equivalent to the ambiguity of adding a homogeneous solution to the current-conservation equation.

The semisimple part of $d$-dimensional Galilean conformal algebra $g^{(d)}$ is given by $h^{(d)}=O(2,1)\oplus O(d)$, which after adding via a semidirect sum the $3d$-dimensional Abelian algebra $t^{(d)}$ of translations, Galilean boosts, and constant accelerations completes the construction. We obtain Galilean superconformal algebra $G^{(d)}$ by first defining the semisimple superalgebra $H^{(d)}$ which supersymmetrizes $h^{(d)}$, and further by considering the expansion of $H^{(d)}$ by tensorial and spinorial graded Abelian charges in order to supersymmetrize the Abelian generators of $t^{(d)}$. For $d=3$ the supersymmetrization of $h^{(3)}$ is linked with a specific model of $\mathcal{N}=4$ extended superconformal mechanics, which is described by the superalgebra $D(2,1;\alpha )$ if $\alpha =1$. We shall also present the alternative derivations of extended Galilean superconformal algebras for $1\le d\le 5$ by employing the Inönü-Wigner contraction method.

For neutrino oscillations to take place the entangled quantum state of a neutrino and a charged lepton produced via charged current interactions must be disentangled. Implementing a nonperturbative Wigner-Weisskopf method we obtain the correct entangled quantum state of neutrinos and charged leptons from the (two-body) decay of a parent particle. The source lifetime and disentanglement length scale lead to a suppression of the oscillation probabilities in short-baseline experiments. The suppression is determined by $\pi L_s/L_{\mathrm{osc}}$ where $L_s$ is the smallest of the decay length of the parent particle or the disentanglement length scale. For $L_s\ge L_{\mathrm{osc}}$ coherence and oscillations are suppressed. These effects are more prominent in short base line experiments and at low neutrino energy. We obtain the corrections to the appearance and disappearance probabilities modified by both the lifetime of the source and the disentanglement scale and discuss their implications for accelerator and reactor experiments. These effects imply that fits to the experimental data based on the usual quantum mechanical formulation underestimate ${sin}^2(2\theta )$ and $\delta m^2$, and are more dramatic for $\delta m^2\simeq {\mathrm{eV}}^2$, the mass range for new generations of sterile neutrinos that could explain the short-baseline anomalies and long disentanglement length scales.

We study the radiation of gravitational waves by self-gravitating binary systems in the low-energy limit of Hořava gravity. We find that the predictions for the energy-loss formula of general relativity are modified already for Newtonian sources: the quadrupole contribution is altered, in part due to the different speed of propagation of the tensor modes; furthermore, there is a monopole contribution stemming from an extra scalar degree of freedom. A dipole contribution only appears at higher post-Newtonian order. We use these findings to constrain the low-energy action of Hořava gravity by comparing them with the radiation damping observed for binary pulsars. Even if this comparison is not completely appropriate—since compact objects cannot be described within the post-Newtonian approximation—it represents an order of magnitude estimate. In the limit where the post-Newtonian metric coincides with that of general relativity, our energy-loss formula provides the strongest constraints for Hořava gravity at low-energies.

We investigate the capability of LISA to measure the sky position of equal-mass, nonspinning black hole binaries, combining for the first time the entire inspiral-merger-ringdown signal, the effect of the LISA orbits, and the complete three-channel LISA response. We consider an ensemble of systems near the peak of LISA’s sensitivity band, with total rest mass of $2\times {10}^6{\mathrm{M}}_{\odot }$, a redshift of $z=1$, and randomly chosen orientations and sky positions. We find median sky localization errors of approximately $\sim 3$ arcminutes. This is comparable to the field of view of powerful electromagnetic telescopes, such as the James Webb Space Telescope, that could be used to search for electromagnetic signals associated with merging massive black holes. We investigate the way in which parameter errors decrease with measurement time, focusing specifically on the additional information provided during the merger-ringdown segment of the signal. We find that this information improves all parameter estimates directly, rather than through diminishing correlations with any subset of well-determined parameters. Although we have employed the baseline LISA design for this study, many of our conclusions regarding the information provided by mergers will be applicable to alternative mission designs as well.