We work in the framework of an inflationary cold dark matter universe with a cosmological constant, in which the cosmological inhomogeneities are considered as gravitational lenses for the CMB photons. This lensing deforms the angular distribution of the CMB maps in such a way that the induced deformations are not Gaussian. Our main goal is the estimation of the deviations with respect to Gaussianity appearing in the distribution of deformations. In the new approach used in this paper, matter is evolved with a particle-mesh N-body code and, then, a useful ray-tracing technique designed to calculate the correlations of the lens deformations induced by nonlinear structures is applied. Our approach is described in detail and tested. Various correlations are estimated at an appropriate angular scale. The resulting values point out both deviations with respect to Gaussian statistics and a low level of correlation in the lens deformations.

Becchi-Rouet-Stora-Tyutin cohomology methods are used to explain the origin of the $\mathrm{SL}(2,R)$ symmetry in Yang-Mills theories. Clear evidence is provided for the unphysical nature of this symmetry. This is obtained from the analysis of a local functional of mass dimension 2 and constitutes a no-go statement for giving a physical meaning to condensates associated with the symmetry breaking of $\mathrm{SL}(2,R).\mathrm{}$

It is shown that, from any n-dimensional Friedmann-Robertson-Walker (FRW) cosmology determined for a single scalar field minimally coupled to gravity, one can construct its m-dimensional counterpart, under the assumption of a common time coordinate and a structurally invariant scale factor for both spacetimes, by means of a simple algebraic correspondence relating gravitational constants and scalar field structural functions. If the considered cosmologies are supplemented with a perfect fluid, fitting a wide class of state equations of the form $p+\rho =\gamma f\left(\rho \right),$ then any n-dimensional FRW cosmology, coupled to a perfect fluid and a scalar field, possesses an m-dimensional counterpart, and vice versa. In particular, these assertions hold for single scalar field inflation models. A theorem on this respect is demonstrated. Various families of solutions are explicitly given and exhibit their correspondence with 3+1 cosmological spacetimes.

Lepton flavor violating processes such as $\overrightarrow{\mu }3e$ and $\overrightarrow{\mu }e\gamma$ are investigated with a supersymmetric Higgs triplet pair $\Delta$ and $\overline{\Delta }$ in light of neutrino masses and experimentally verifiable leptogenesis. The Higgs triplet mass $M_{\Delta }$ is expected to be in the range of $1–100\mathrm{TeV}.$ The branching ratios of these charged lepton decays are evaluated in terms of $M_{\Delta }$ and the coupling $\mathrm{fL}\Delta L$ of the Higgs triplet $\Delta$ with lepton doublet pairs LL, which is proportional to the neutrino mass matrix. They may be reached in future collider experiments. In particular, the $\overrightarrow{\mu }3e$ decay would be observed indicating the existence of Higgs triplets with $M_{\Delta }\sim 1–100\mathrm{TeV}$ for $|f|\sim 0.1–1,$ while the $\overrightarrow{\mu }e\gamma$ decay can be significant irrespective of $M_{\Delta }$ in the supersymmetric model due to the flavor violation in the slepton mass matrices induced by the renormalization effects.

In this paper we study the gauge mediation signal with the ATLAS detector at the CERN Large Hadron Collider. We focus on the case where next lightest supersymmetric particle is the long-lived lightest neutralino $\left({\tilde{\chi }}_1^0\right),$ which decays predominantly into a photon $\left(\gamma \right)$ and a gravitino $\left(\tilde{G}\right).\mathrm{}$ A nonpointing photon from the neutralino decay can be detected with good position and time resolution by the electromagnetic calorimeter (ECAL), while the photon momentum could be precisely measured if the photon were converted inside the inner tracking detector before reaching the ECAL. A new technique is developed to determine the masses of the slepton $\left(\mathcal{l}̃\right)$ and the neutralino from events with a lepton and a converted nonpointing photon arising from the cascade decay $\mathcal{l}\overrightarrow{̃}\mathcal{l}{\tilde{\chi }}_1^0\to \mathcal{l}\gamma \tilde{G}.$ A Monte Carlo simulation at a sample point shows that the masses could be measured with an error of 3% for $O\left(100\right)\mathrm{}$ selected $\mathcal{l}\gamma$ pairs. Once the sparticle masses are determined by this method, the decay time and momentum of the neutralino are solved using the ECAL data and the lepton momentum only, for all $\mathcal{l}\gamma$ pairs without the photon conversion. We estimate the sensitivity to the neutralino lifetime for $c\tau =10\mathrm{}\mathrm{cm}$ to $O\left(10\right)\mathrm{}\mathrm{m}.$

In this work we investigate $q\overline{q}$ spectra and wave functions of light front transverse lattice Hamiltonians that result from different methods of formulating fermions on the transverse lattice. We adopt the one link approximation for the transverse lattice and discrete light cone quantization (DLCQ) to handle longitudinal dynamics. We perform a detailed study of the continuum limit of DLCQ and associated techniques to manage severe light front infrared divergences. We explore the effects of various parameters of the theory, especially the strength of the helicity-flip interaction and the link mass on spectra and wave functions.

We propose a general method to study the solutions to nonlinear QCD evolution equations, based on a deep analogy with the physics of traveling waves. In particular, we show that the transition to the saturation regime of high energy QCD is identical to the formation of the front of a traveling wave. Within this physical picture, we provide the expressions for the saturation scale and the gluon density profile as a function of the total rapidity and the transverse momentum. The application to the Balitskiĭ-Kovchegov equation for both fixed and running coupling constants confirms the effectiveness of this method.

We have studied the charged multiplicity distributions arising from $p-p$ and $p-\overline{p}$ collisions over the range of center of mass energies from 30 to 1800 GeV. We find that a portion of each distribution does obey Koba-Nielsen-Olesen (KNO) scaling. Those parts of the distributions that do not scale are the result of collisions which are initiated by multiparton collisions. Results from experiment E735 show not only collisions initiated by double but also good evidence for triple parton-parton collisions. These multi-parton collisions seem to account for essentially all the increase in the nonsingle diffractive inelastic cross section in this energy domain. The threshold for multiparton collisions seems to be associated with the advent of sea quarks in the structure function of the proton. We have developed a means of extrapolating these results to higher energies. The results indicate that small Feynman x partons seem to become more dominant as the energy is increased. It seems very likely that the sea quarks are important at larger impact parameters than the valence quarks. This means that the gluons and sea quarks are increasingly important in describing the collisions as the energy grows. The threshold for multiparton collisions seems to be associated with the advent of the sea quarks in the reactions.

It is well known that Yukawa potentials permit bound states in the Schrödinger equation only if the ratio of the exchanged mass to bound mass is below a critical multiple of the coupling constant. However, arguments suggested by the Darwin term imply a more complex situation. By numerically studying the Dirac equation with a Yukawa potential we investigate this “amplification” effect.

We study the dependence on the number of colors of the leading $\pi \pi$ scattering amplitude in chiral dynamics. We demonstrate the existence of a critical number of colors for and above which the low energy $\pi \pi$ scattering amplitude computed from the simple sum of the current algebra and vector meson terms is crossing symmetric and unitary at leading order in a truncated and regularized ${1/N}_c$ expansion. The critical number of colors turns out to be $N_c=6\mathrm{}$ and is insensitive to the explicit breaking of chiral symmetry. Below this critical value, an additional state is needed to enforce the unitarity bound; it is a broad one, most likely of a “four quark” nature.

For the $N\overline{N}$ system, the one-pion-exchange (OPE) interaction gives the largest attractive force for $N\overline{N}$ with an isospin $I=0\mathrm{}$ and spin $S=0,$ while a near-threshold enhancement was observed for $p\overline{p}$ with $I=0\mathrm{}$ and $S=0\mathrm{}$ in $J/\overrightarrow{\psi }\gamma p\overline{p}$ decays. With a K-matrix approach, we find that the OPE final-state interaction makes an important contribution to the near-threshold enhancement in the $p\overline{p}$ mass spectrum in $J/\overrightarrow{\psi }\gamma p\overline{p}$ decays.

The estimation of the signal frequency count in the presence of background noise has been widely discussed in recent physics literature, and Mandelkern [Stat. Sci. 17, 149 (2002)] brings the central issues to the statistical community, leading in turn to extensive discussion by statisticians. The primary focus however of Mandelkern and the accompanying discussion is on the construction of a confidence interval. We argue that the likelihood function and p-value function provide a comprehensive presentation of the information available from the model and the data. This is illustrated for Gaussian and Poisson models with lower bounds for the mean parameter.

We reevaluate our published calculations of electromagnetic showers generated by GEANT 3.21 and the radio frequency pulses they produce in ice. We are prompted by a recent report showing that GEANT 3.21–modeled showers are sensitive to internal settings in the electron tracking subroutine. We report the shower and pulse characteristics obtained with different settings of GEANT 3.21 and with GEANT 4. The default setting of electron tracking in GEANT 3.21 we used in previous work speeds up the shower simulation at the cost of information near the end of the tracks. We find that settings tracking $e^{-}$ and $e^{+}$ to lower energy yield a more accurate calculation, a more intense shower, and proportionately stronger radio pulses at low frequencies. The key features of the showers and pulses agree among GEANT 4 and Zas, Halzen, and Stanev and properly set GEANT 3.21 codes. At high frequencies the relation between the shower tracking algorithm and the pulse spectrum is more complex. We obtain radial distributions of shower particles and phase distributions of pulses from 100 GeV showers that are consistent with our published results.

Attempts to solve Yang-Mills theory must eventually face the problem of analyzing the theory at intermediate values of the coupling constant. In this regime neither perturbation theory nor the gravity dual are adequate, and one must consider the full string theory in the appropriate background. We suggest that in some nontrivial cases the world sheet theory may be exactly solvable. For the Green-Schwarz superstring on ${\mathrm{AdS}}_5\times {\mathrm{S}}^5$ we find an infinite set of nonlocal classically conserved charges of the type that exist in integrable field theories.

We compare quark stars made of color-superconducting quark matter to normal-conducting quark stars. We focus on the most simple color-superconducting system, a two-flavor color superconductor, and employ the Nambu–Jona-Lasinio (NJL) model to compute the gap parameter and the equation of state. By varying the strength of the four-fermion coupling of the NJL model, we study the mass and the radius of the quark star as a function of the value of the gap parameter. If the coupling constant exceeds a critical value, the gap parameter does not vanish even at zero density. For coupling constants below this critical value, mass and radius of a color-superconducting quark star change at most by $\sim 20\%$ compared to a star consisting of normal-conducting quark matter. For coupling constants above the critical value, mass and radius may change by factors of two or more.

We study kink or domain wall solutions in $O\left(10\right)\mathrm{}$ Higgs models in the context of the “clash of symmetries” mechanism developed by Davidson, Toner, Volkas and Wali and, independently, by Pogosian and Vachaspati. We show that kink configurations employing Higgs fields in the $45$ (the adjoint representation) of $O\left(10\right)\mathrm{}$ break up into three classes: those that at finite distances from the wall respect a $U\left(5\right)\mathrm{}$ subgroup of $\mathrm{SO}\left(10\right),$ and two others that respect the smaller subgroups $U\left(3\right)\mathrm{}\otimes U\left(2\right)\mathrm{}$ and $U\left(4\right)\mathrm{}\otimes U\left(1\right).$ These smaller subgroups arise from the clash of symmetries mechanism: they are the intersections of two differently embedded $U\left(5\right)\mathrm{}$ subgroups of $\mathrm{SO}\left(10\right),$ the latter being the symmetries respected in asymptotia on opposite sides of the domain wall. The existence of the $\mathrm{SO}\left(10\right)\mathrm{}\to U\left(3\right)\mathrm{}\otimes U\left(2\right)=SU\left(3\right)\mathrm{}\otimes \mathrm{SU}\left(2\right)\mathrm{}\otimes U\left(1\right)\mathrm{}\otimes {U\left(1\right)\mathrm{}}^{\prime }\equiv G_{\mathrm{SM}}\otimes {U\left(1\right)\mathrm{}}^{\prime }$ class advances the search for a realistic brane world model wherein some of the required symmetry breaking is achieved via the clash of symmetries rather than the conventional mechanism. At the centers of the walls, the unbroken symmetries are enhanced. In the $U\left(3\right)\mathrm{}\otimes U\left(2\right)\mathrm{}$ case, the symmetry is $O\left(6\right)\mathrm{}\otimes U\left(2\right),$ which is closely related to the Pati-Salam-like $\mathrm{SU}\left(4\right)\mathrm{}\otimes \mathrm{SU}\left(2\right)\mathrm{}\otimes U\left(1\right)\mathrm{}$ group. If our universe is a brane located at the center of such a wall, then we see the $O\left(10\right)\mathrm{}$ symmetry as being strongly broken to $\mathrm{SU}\left(4\right)\mathrm{}\otimes \mathrm{SU}\left(2\right)\mathrm{}\otimes U\left(1\right).$ Interestingly, if the brane-world degrees of freedom enjoy a slight leakage off the wall, then an additional symmetry breakdown to $U\left(3\right)\mathrm{}\otimes {U\left(2\right)=G}_{\mathrm{SM}}\otimes {U\left(1\right)\mathrm{}}^{\prime }$ is effectively induced on the brane. This provides a possible framework within which to address at least part of a gauge hierarchy problem: $O\left(10\right)\mathrm{}$ is strongly broken to $\mathrm{SU}\left(4\right)\mathrm{}\otimes \mathrm{SU}\left(2\right)\mathrm{}\otimes U\left(1\right),$ then more weakly to $G_{\mathrm{SM}}\otimes {U\left(1\right)\mathrm{}}^{\prime }$ depending on the amount of leakage off the brane. We also comment on kinks employing the $10$ and $54$ of $O\left(10\right).$

We reexamine the proposal that the resolution of the cosmological constant problem involves a submillimeter breakdown of the point-particle approximation for gravitons. No fundamental description of such a breakdown, which simultaneously preserves the point-particle nature of matter particles, is yet known. However, basic aspects of the self-consistency of the idea, such as the preservation of the macroscopic equivalence principle while satisfying the quantum naturalness of the cosmological constant, are addressed in this paper within a soft graviton effective theory. It builds on Weinberg’s analysis of soft graviton couplings and standard heavy particle effective theory, and minimally encompasses the experimental regime of soft gravity coupled to hard matter. A qualitatively distinct signature for short-distance tests of gravity is discussed, bounded by naturalness to appear above approximately $20\mu \mathrm{m}.$

A method to construct exact general relativistic thick disks that is a simple generalization of the “displace, cut, and reflect” method commonly used in Newtonian, as well as, in Einstein theory of gravitation is presented. This generalization consists in the addition of a new step in the above mentioned method. The new method can be pictured as a “displace, cut, fill, and reflect” method. In the Newtonian case, the method is illustrated in some detail with the Kuzmin-Toomre disk. We obtain a thick disk with acceptable physical properties. In the relativistic case two solutions of the Weyl equations, the Weyl gamma metric (also known as the Zipoy-Voorhees metric) and the Chazy-Curzon metric, are used to construct thick disks. Also, the Schwarzschild metric in isotropic coordinates is employed to construct another family of thick disks. In all the considered cases we have nontrivial ranges of the involved parameter that yield thick disks in which all the energy conditions are satisfied.

The spectrum of multiple level transitions of a quantum black hole is considered and the linewidths calculated. Initial evidence is found for these higher order transitions in the spectrum of quasinormal modes for Schwarzschild and Kerr black holes, further bolstering the idea that there exists a correspondence principle between quantum transitions and classical “ringing modes.” Several puzzles are noted, including a fine-tuning problem between the linewidth and level degeneracy. A more general explanation is provided for why setting the Immirzi parameter of loop quantum gravity from the black hole spectrum necessarily gives the correct value for the black hole entropy.