We investigate the effect of unparticle self-interactions at the Large Hadron Collider (LHC). Especially, we discuss the three-point correlation function, which is determined by conformal symmetry up to a constant, and study its relation to processes with four-particle final states. These processes could be used as a favorable way to look for unparticle physics, and for weak enough couplings to the standard model, even the only way. We find updated upper bounds on the cross sections for unparticle-mediated $4\gamma$ final states at the LHC and novel upper bounds for the corresponding $2\gamma 2\ell$ and $4\ell$ final states. The size of the allowed cross sections obtained are comparably large for large values of the scaling dimension of the unparticle sector, but they decrease with decreasing values of this parameter. In addition, we present relevant distributions for the different final states, enabling the possible identification of the unparticle scaling dimension if there was to be a large number of events of such final states at the LHC.

We study the implications of several recent high-precision measurements of the pion form factor in the region of the $\rho -\omega$ interference shoulder for (i) the extraction of the $\rho -\omega$ mixing matrix element, ${\Pi }_{\rho \omega }(m_{\rho }^2)$, and (ii) the evaluation of the isospin-breaking correction needed to incorporate hadronic $\tau$ decay data into the determination of the standard model expectation for the leading order hadronic contribution, $[a_{\mu }{]}_{\mathrm{had}}^{\mathrm{LO}}$, to the anomalous magnetic moment of the muon, focussing, in the latter case, on the model dependence of the $\rho -\omega$ mixing component of the isospin-breaking correction. We consider a range of different models for the broad $\rho$ contribution to the $e^{+}{e}^{-}\to \pi \pi$ amplitude, applying these models to each experimental data set, and find that the model dependence of the $\rho -\omega$ mixing correction is significantly larger than the uncertainty induced by experimental errors for any individual model. We also find that, for each such model, the recent data allows one to separate $\rho -\omega$ mixing and direct $\omega \to \pi \pi$ coupling contributions to the amplitude, and hence to obtain a reasonably precise extraction of ${\Pi }_{\rho \omega }(m_{\rho }^2)$, uncontaminated by direct $\omega \to \pi \pi$ coupling effects, for use in meson-exchange model calculations of charge symmetry breaking in $NN$ scattering.

We show that strongly coupled field theories with holographic gravity duals at finite charge density and low temperatures can undergo de Haas–van Alphen quantum oscillations as a function of an external magnetic field. Exhibiting this effect requires computation of the one-loop contribution of charged bulk fermions to the free energy. The one-loop calculation is performed using a formula expressing determinants in black hole backgrounds as sums over quasinormal modes. At zero temperature, the periodic nonanalyticities in the magnetic susceptibility as a function of the inverse magnetic field depend on the low energy scaling behavior of fermionic operators in the field theory, and are found to be softer than in weakly coupled theories. We also obtain numerical and WKB results for the quasinormal modes of charged bosons in dyonic black hole backgrounds, finding evidence for nontrivial periodic behavior as a function of the magnetic field.

We report the first operation of a rotating odd-parity Lorentz invariance test in electrodynamics using a microwave Mach-Zehnder interferometer with permeable material in one arm. The experiment sets a direct bound to ${\kappa }_{\mathrm{tr}}$ of $-0.3\pm 3\times {10}^{-7}$. Using new power recycled waveguide interferometer techniques (with the highest spectral resolution ever achieved of $2\times {10}^{-11}\mathrm{rad}/\sqrt{\mathrm{Hz}}$) we show an improvement of several orders of magnitude is attainable in the future.

This paper generalizes the structure of gravitational waves from orbiting spinning binaries under leading order spin-orbit coupling, as given in the work by Königsdörffer and Gopakumar [Phys. Rev. D 71, 024039 (2005)] for single-spin and equal-mass binaries, to unequal-mass binaries and arbitrary spin configurations. The orbital motion is taken to be quasicircular and the fractional mass difference is assumed to be small against one. The emitted gravitational waveforms are given in analytic form.

The cosmological singularities of the Bianchi I universe are analyzed in the setting of loop geometry underlying the loop quantum cosmology. We solve the Hamiltonian constraint of the theory and find the Lie algebra of elementary observables. Physical compound observables are defined in terms of elementary ones. Modification of classical theory by holonomy around a loop removes the singularities. However, our model has a free parameter that cannot be determined within our method. Testing the model by the data of observational cosmology may be possible after quantization of our modified classical theory.

In the quantization of simple cosmological models (minisuperspace models) described by the Wheeler-DeWitt equation, an important step is the construction, from the wave function, of a probability distribution answering various questions of physical interest, such as the probability of the system entering a given region of configuration space at any stage in its entire history. A standard but heuristic procedure is to use the flux of (components of) the wave function in a WKB approximation. This gives sensible semiclassical results but lacks an underlying operator formalism. In this paper, we address the issue of constructing probability distributions linked to the Wheeler-DeWitt equation using the decoherent histories approach to quantum theory. The key step is the construction of class operators characterizing questions of physical interest. Taking advantage of a recent decoherent histories analysis of the arrival time problem in nonrelativistic quantum mechanics, we show that the appropriate class operators in quantum cosmology are readily constructed using a complex potential. The class operator for not entering a region of configuration space is given by the $S$ matrix for scattering off a complex potential localized in that region. We thus derive the class operators for entering one or more regions in configuration space. The class operators commute with the Hamiltonian, have a sensible classical limit, and are closely related to an intersection number operator. The definitions of class operators given here handle the key case in which the underlying classical system has multiple crossings of the boundaries of the regions of interest. We show that oscillatory WKB solutions to the Wheeler-DeWitt equation give approximate decoherence of histories, as do superpositions of WKB solutions, as long as the regions of configuration space are sufficiently large. The corresponding probabilities coincide, in a semiclassical approximation, with standard heuristic procedures. In brief, we exhibit the well-defined operator formalism underlying the usual heuristic interpretational methods in quantum cosmology.

A convincing detection of primordial non-Gaussianity in the local form of the bispectrum, whose amplitude is given by the $f_{\mathrm{NL}}$ parameter, offers a powerful test of inflation. In this paper, we calculate the modification of two-point cross-correlation statistics of weak lensing—galaxy-galaxy lensing and galaxy-cosmic microwave background (CMB) crosscorrelation—due to $f_{\mathrm{NL}}$. We derive and calculate the covariance matrix of galaxy-galaxy lensing, including cosmic variance terms. We focus on large scales ($l<100$) for which the shape noise of the shear measurement becomes irrelevant and cosmic variance dominates the error budget. For a modest degree of non-Gaussianity, $f_{\mathrm{NL}}=\pm 50$ modifications of the galaxy-galaxy-lensing signal at the 10% level are seen on scales $R\sim 300\mathrm{Mpc}$, and grow rapidly toward larger scales as $\propto R^2$. We also see a clear signature of the baryonic acoustic oscillation feature in the matter power spectrum at $\sim 150\mathrm{Mpc}$, which can be measured by next-generation lensing experiments. In addition, we can probe the local-form primordial non-Gaussianity in the galaxy-CMB lensing signal by correlating the lensing potential reconstructed from CMB with high-$z$ galaxies. For example, for $f_{\mathrm{NL}}=\pm 50$, we find that the galaxy-CMB lensing cross-power spectrum is modified by $\sim 10\%$ at $l\sim 40$, and by a factor of 2 at $l\sim 10$, for a population of galaxies at $z=2$ with a bias of 2. The effect is greater for more highly biased populations at larger $z$; thus, high-$z$ galaxy surveys cross correlated with CMB offer a yet another probe of primordial non-Gaussianity.

We compute the second-order matching conditions for tensor metric perturbations at an abrupt change in the equation of state. For adiabatic perturbations on large scales the matching hypersurface coincides with a uniform-density hypersurface. We show that in the uniform-density gauge both the tensor perturbation and its time-derivative are continuous in this case. For nonadiabatic perturbations, the matching hypersurface need not coincide with a uniform-density hypersurface, and the tensor perturbation in the uniform-density gauge may be discontinuous. However, we show that in the Poisson gauge both the tensor perturbation and its time derivative are continuous for adiabatic or nonadiabatic perturbations. As an application we solve the evolution equation for second-order tensor perturbations on large scales for a constant equation of state, and we use the matching conditions to evolve the solutions through the transition from an inflationary era to a radiation era. We show that in the radiation era the resulting free part of the large-scale tensor perturbation (constant mode) is slow-roll suppressed in both the uniform-density and Poisson gauges. Thus, we conclude that second-order gravitational waves from slow-roll inflation are suppressed.

The Dirac-Born-Infeld (DBI) action from string theory provides several new classes of dark energy behavior beyond quintessence due to its relativistic kinematics. We constrain parameters of natural potentials and brane tensions with cosmological observations as well as showing how to design these functions for a desired expansion history. We enlarge the attractor solutions, including new ways of obtaining cosmological constant behavior, to the case of generalized DBI theory with multiple branes. An interesting novel signature of DBI attractors is that the sound speed is driven to zero, unlike for quintessence where it is the speed of light.

We investigate the shear viscosity of neutron star matter in the presence of an antikaon condensate. The electron and muon number densities are reduced due to the appearance of a $K^{-}$ condensate in neutron star matter, whereas the proton number density increases. Consequently, the shear viscosity due to scatterings of electrons and muons with themselves and protons is lowered compared to the case without the condensate. On the other hand, the contribution of proton-proton collisions to the proton shear viscosity through electromagnetic and strong interactions becomes important and comparable to the neutron shear viscosity.

Many proposals have been put forward to explore four-quark states $QQ\overline{q}\overline{q}$ ($Q=s$, $c$, $b$; $q=u$, $d$) by experiment, so a systematic study of $QQ\overline{q}\overline{q}$ spectrum with different constituent quark models by a high precision, few-body method, the Gaussian expression method, is useful. Three quark models: the Bhaduri, Cohler, Nogami quark model, the chiral quark model (ChQM), and the quark delocalization color screening model are all employed for a systematic calculation of the $S$-wave $QQ\overline{q}\overline{q}$ spectrum with different color structures, using the Gaussian expression method. The results show that only the $bb\overline{q}\overline{q}$ state with $(I,J)=(0,1)$ is bound in different color structures within the different quark models. The binding energy varies from several MeV for a di-meson structure to over 100 MeV for a diquark-antidiquark structure. For the $cc\overline{q}\overline{q}$ system, the state with $(I,J)=(0,1)$ is bound in a di-meson structure, and also bound in a diquark-antidiquark structure if pseudoscalar meson exchanges are accounted for. All are weakly bound states. The mixture of diquark-antidiquark and molecular structures is discussed in the framework of quark models for the first time; $cc\overline{q}\overline{q}$ with $(I,J)=(0,1)$ is below the threshold in addition to $bb\overline{q}\overline{q}$ in both the ChQM and the Bhaduri, Cohler, Nogami quark model. In the same channel, $ss\overline{q}\overline{q}$ is also a possible bound state with mass around 1.4 GeV in ChQM.

Doubly charged Higgs bosons, $H^{\pm \pm }$, are being searched for in the Tevatron experiments. The most recent search by the D0 Collaboration seeks three muons (${\mu }^{\pm }{\mu }^{\pm }{\mu }^{\mp }$), which are assumed to originate from the pair-production process, $q\overline{q}\to H^{++}{H}^{--}$, followed by the decay $H^{\pm \pm }\to {\mu }^{\pm }{\mu }^{\pm }$. In this three-lepton ($3\ell$) channel there are six distinct signatures for $\ell =e$ or $\mu$. In the context of the Higgs Triplet Model, we quantify the dependence of the event numbers for the $3\ell$ channels on the parameters of the neutrino mass matrix. It is also shown that the inclusion of the production mechanism $q{\overline{q}}^{\prime }\to H^{\pm \pm }{H}^{\mp }$, followed by the decay $H^{\pm }\to {\ell }^{\pm }\nu$, would significantly increase the discovery potential in these channels. We then provide perspectives on the production of these channels at the Tevatron and LHC.

We consider the differential and total cross sections for proton-proton and proton-antiproton scattering in the Regge regime from the point of view of string dual models of QCD. We argue that the form factor which appears in the differential cross section is related to the matrix element of the stress tensor between proton states and give a procedure for computing the strength of the coupling of the Pomeron trajectory to the proton. We compute this coupling in the Sakai-Sugimoto model and find excellent agreement with the data at large $s$ and small $t$. The form factor can be estimated in the Skyrme model or in AdS/QCD models and gives a stiffer form factor than the commonly used electromagnetic form factor, in agreement with our fits to data. Our model is also in good agreement with the measured ratio of real to imaginary parts of the forward scattering amplitude at large $s$.

The classical internal structure of spinning black holes is vastly different from that of static black holes. We consider spinning Banados-Teitelboim-Zanelli black holes, and probe their interior from the gauge theory. Utilizing the simplicity of the geometry and reverse engineering from the geodesics, we propose a thermal correlator construction which can be interpreted as arising from two entangled conformal field theories. By analytic continuation of these correlators, we can probe the Cauchy horizon. Correlators that capture the Cauchy horizon in our work have a structure closely related to those that capture the singularity in a nonrotating Banados-Teitelboim-Zanelli. As expected, the regions beyond the Cauchy horizon are not probed in this picture, protecting cosmic censorship.

The framework of slowly evolving horizons is generalized to the case of black branes in asymptotically anti–de Sitter spaces in arbitrary dimensions. The results are used to analyze the behavior of both event and apparent horizons in the gravity dual to boost-invariant flow. These considerations are motivated by the fact that at second order in the gradient expansion the hydrodynamic entropy current in the dual Yang-Mills theory appears to contain an ambiguity. This ambiguity, in the case of boost-invariant flow, is linked with a similar freedom on the gravity side. This leads to a phenomenological definition of the entropy of black branes. Some insights on fluid/gravity duality and the definition of entropy in a time-dependent setting are elucidated.

The decoupling limit of a certain configuration of D3 branes in a Melvin universe defines a sector of string theory known as puff field theory (PFT)—a theory with nonlocal dynamics but without gravity. In this work, we present a systematic analysis of the nonlocal states of strongly coupled PFT using gravitational holography. And we are led to a remarkable new holographic dictionary. We show that the theory admits states that may be viewed as brane protrusions from the D3 brane worldvolume. The footprint of a protrusion has finite size—the scale of nonlocality in the PFT—and corresponds to an operator insertion in the PFT. We compute correlators of these states, and we demonstrate that only part of the holographic bulk is explored by this computation. We then show that the remaining space holographically encodes the dynamics of the D3 brane tentacles. The two sectors are coupled: in this holographic description, this is realized via quantum entanglement across a holographic screen—a throat in the geometry—that splits the bulk into the two regions in question. We then propose a description of PFT through a direct product of two Fock spaces—akin to other nonlocal settings that employ quantum group structures.

In supersymmetric theories, the presence of axions usually implies the existence of a noncompact, (pseudo)moduli space. In gauge-mediated models, the axion would seem a particularly promising dark matter candidate. The cosmology of the moduli then constrains the gravitino mass and the axion decay constant; the former cannot be much below 10 MeV; the latter cannot be much larger than ${10}^{13}\mathrm{GeV}$. Axinos, when identifiable, are typically heavy and do not play an important role in cosmology.

The Dyson equation proposed for planar temporal Wilson loops in the context of supersymmetric gauge theories is critically analyzed thereby exhibiting its ingredients and approximations involved. We reveal its limitations and identify its range of applicability in nonsupersymmetric gauge theories. In particular, we show that this equation is applicable only to strongly asymmetric planar Wilson loops (consisting of a long and a short pair of loop segments) and as a consequence the Wilsonian potential can be extracted only up to intermediate distances. By this equation the Wilson loop is exclusively determined by the gluon propagator. We solve the Dyson equation in Coulomb gauge for the temporal Wilson loop with the instantaneous part of the gluon propagator and for the spatial Wilson loop with the static gluon propagator obtained in the Hamiltonian approach to continuum Yang-Mills theory and on the lattice. In both cases we find a linearly rising color potential.

We investigate the entanglement of a quantum field in the expanding universe. By introducing a bipartite system using a coarse-grained scalar field, we apply the separability criterion based on the partial transpose operation and numerically calculate the bipartite entanglement between separate spatial regions. We find that the initial entangled state becomes separable or disentangled after the spatial separation of two points exceed the Hubble horizon. This provides the necessary conditions for the appearance of classicality of the quantum fluctuation. We also investigate the condition of classicality that the quantum field can be treated as the classical stochastic variables.