An investigation is performed of the Lorentz-violating electrodynamics extracted from the renormalizable sector of the general Lorentz- and CPT-violating standard-model extension. Among the unconventional properties of radiation arising from Lorentz violation is birefringence of the vacuum. Limits on the dispersion of light produced by galactic and extragalactic objects provide bounds of $3\times {10}^{-16}$ on certain coefficients for Lorentz violation in the photon sector. The comparative spectral polarimetry of light from cosmologically distant sources yields stringent constraints of $2\times {10}^{-32}.$ All remaining coefficients in the photon sector are measurable in high-sensitivity tests involving cavity-stabilized oscillators. Experimental configurations in Earth- and space-based laboratories are considered that involve optical or microwave cavities and that could be implemented using existing technology.

We investigate the production, signatures, and backgrounds of a pair of heavy-exotic charged leptons and a heavy-exotic neutrino in association with the exotic charged lepton in the framework of the vector singlet model, vector doublet model, and fermion-mirror-fermion model, at the CERN Large Hadron Collider. We show that the cross sections for the production of a pair of heavy exotic leptons are competitive with the ones for the single production of exotic leptons.

We investigate what can be learned at a linear collider about the sector of electroweak symmetry breaking from a precise measurement of the Higgs boson production cross section through the process $e^{+}{e}^{-}\to \mathrm{hZ}.\mathrm{}$ We focus on deviations from the standard model arising in its minimal supersymmetric extension. The analysis is performed within two realistic future scenarios, taking into account all prospective experimental errors on supersymmetric particle masses as well as uncertainties from unknown higher order corrections. We find that information on $\tan \beta$ and $M_A$ could be obtained from a cross section measurement with a precision of $0.5-1\%.\mathrm{}$ Alternatively, information could be obtained on the gaugino mass parameters $M_2$ and $\mu$ if they are relatively small, $M_2,\mu \approx 200\mathrm{GeV}.$

In a recent work we introduced a nonlocal version of the Nambu–Jona-Lasinio (NJL) model that was designed to generate a quark self-energy in Euclidean space that was similar to that obtained in lattice simulations of QCD. In the present work we carry out related calculations in Minkowski space, so that we can study the effects of the significant vector and axial-vector interactions that appear in extended NJL models and which play an important role in the study of the $\rho ,$ $\omega$ and $a_1$ mesons. We study the modification of the quark self-energy in the presence of matter and find that our model reproduces the behavior of the quark condensate predicted by the model-independent relation $〈\overline{q}q{〉}_{\rho }=〈\overline{q}q{〉}_0(1\mathrm{}-{\sigma }_N{\rho }_N{/f}_{\pi }^2{m}_{\pi }^2+\cdot \cdot \cdot ),$ where ${\sigma }_N$ is the pion-nucleon sigma term and ${\rho }_N$ is the density of nuclear matter. (Since we do not include a model of confinement, our study is restricted to the analysis of quark matter. We provide some discussion of the modification of the above formula for quark matter.) We find a restoration of chiral symmetry of about 80% at twice the nuclear matter density for the model considered in this work. We also find that the part of the quark self-energy that is explicitly dependent upon the density has a strong negative scalar term and a strong positive vector term, which is analogous to the self-energy found for the nucleon in nuclear matter when one makes use of the Dirac equation for the nucleon. In this work we calculate the nucleon self-energy in nuclear matter using our model of the quark self-energy and obtain satisfactory results in agreement with the values of the scalar and vector nucleon potentials in matter found in either theoretical or phenomenological studies.

There are three parameter degeneracies inherent in the three-neutrino analysis of long-baseline neutrino experiments. We develop a systematic method for determining whether or not a set of measurements in neutrino oscillation appearance experiments with approximately monoenergetic beams can completely resolve these ambiguities. We then use this method to identify experimental scenarios in which the parameter degeneracies may be efficiently resolved. Generally speaking, with two appearance measurements degeneracies can occur over wide areas of the $(\delta ,{\theta }_{13})$ parameter space; with three measurements they occur along lines in the parameter space and with four measurements they occur only at isolated points. If two detectors are placed at the same distance from the source but at different locations with respect to the main axis of the beam (a detector cluster), each detector will measure neutrinos at different energies. Then one run with neutrinos and one run with antineutrinos will give the four independent measurements that in principle can resolve all of the parameter degeneracies if ${\sin }^{2}2{\theta }_{13}>~\mathrm{0.002.}$ We also examine scenarios with detector clusters using only neutrino beams. Without detector clusters, the measurement of neutrinos and antineutrinos at a short distance and only neutrinos at a longer distance may also work.

We present an analysis of the solar neutrino data assuming the deficit of solar neutrinos to originate from the interaction of their transition magnetic moments with the solar magnetic field. We perform fits to the rates only and global fits and consider separately the existing data prior to the announcement of the SNO neutral current results, and the present data. Predictions for the Borexino experiment are also derived. The solar field profiles are taken both in the radiation zone and core of the Sun, and in the convective zone. The latter are chosen so as to exhibit a rapid increase across the bottom of the convective zone and a moderate decrease toward the surface. Regarding the field profiles in the radiative zone and core, it is found that the data show a preference for those cases in which a strong field rests at the solar center with a steep decrease thereafter. For these, the quality of the global fits is as good as the one from the best oscillation solutions and the same as for the convective zone profiles examined. It is also found that the ${\chi }^2$ of the fits increases when the most recent data are considered, owing to the smaller errors involved. This in turn provides more precise predictions for Borexino than previous ones, thus resulting in a clearer possible distinction between magnetic moment and the currently favored oscillation solutions.

We investigate whether present data on helioseismology and solar neutrino fluxes may constrain weakly interacting massive particle (WIMP)-matter interactions in the range of WIMP parameters under current exploration in WIMP searches. We find that, for a WIMP mass of 30 GeV, once the effect of the presence of WIMPs in the Sun’s interior is maximized, the squared isothermal sound speed is modified, with respect to the standard solar model, by at most 0.4% at the Sun’s center. The maximal effect on the ${}^8\mathrm{B}$ solar neutrino flux is a reduction of 4.5%. Larger masses lead to smaller effects. These results imply that present sensitivities in the measurements of solar properties, though greatly improved in recent years, do not provide information or constraints on WIMP properties of relevance for dark matter. Furthermore, we show that, when current bounds from direct WIMP searches are taken into account, the effect induced by WIMPs with dominant coherent interactions is drastically reduced as compared to the values quoted above. The case of neutralinos in the minimal supersymmetric standard model is also discussed.

Freedom from global anomalies in the presence of a local ${\mathrm{SU}\left(2\right)\mathrm{}}_H$ horizontal symmetry under which right-handed charged leptons transform nontrivially requires that there be at least two right-handed neutrinos with masses of order of the horizontal symmetry breaking scale. If a third right-handed neutrino is introduced to satisfy quark lepton symmetry, it is unprotected by the horizontal symmetry, becomes superheavy with a Planck scale mass, and decouples from lower-energy physics. The resulting seesaw mechanism with two right-handed neutrinos in combination with the horizontal symmetry leads naturally to a near bimaximal pattern for the neutrino mixing with an inverted mass hierarchy and is compatible with all data. It predicts a correlation between the solar mixing angle and $U_{e3\mathrm{}}$ that is testable in the proposed long baseline experiments.

I perform some analytic continuations of the de Sitter thick domain wall solutions obtained in my previous paper in the system of gravity and a scalar field with an axionlike potential. The obtained new solutions represent anti–de Sitter thick domain walls and cosmology. The anti–de Sitter domain wall solutions are periodic, and correspondingly the cosmological solutions represent cyclic universes. I parametrize the axionlike scalar field potential and determine the parameter regions of each type of solutions.

In a supersymmetric large extra dimension scenario, the production of Kaluza-Klein gravitinos accompanied by a photino at $e^{+}{e}^{-}$ colliders is studied. We assume that a bulk supersymmetry is softly broken on our brane such that the low-energy theory resembles the MSSM. Low energy supersymmetry breaking is further assumed as in GMSB, leading to a sub-eV mass shift in each KK mode of the gravitino from the corresponding graviton KK mode. Since the photino decays within a detector due to the sufficiently large inclusive decay rate of $\tilde{\gamma }\to \gamma \tilde{G},$ the process $e^{+}{e}^{-}\to \tilde{\gamma }\tilde{G}$ yields single photon events with missing energy. Even if the total cross section can be substantial at $\sqrt{s}=500\mathrm{}\mathrm{GeV},$ the KK graviton background of $e^{+}{e}^{-}\to \gamma G$ is kinematically advantageous and thus much larger. It is shown that the observable $\Delta {\sigma }_{\mathrm{LR}}\equiv \sigma {(e}_L^{-}{e}_R^{+}\left)-\sigma {(e}_R^{-}{e}_L^{+}\right)$ can completely eliminate the KK graviton background but retain most of the KK gravitino signal, which provides a unique and robust method to probe the supersymmetric bulk.

We propose a simple explanation for the connection between chiral symmetry restoration and deconfinement in QCD at high temperature. In the Higgs description of the QCD vacuum both spontaneous chiral symmetry breaking and effective gluon masses are generated by the condensate of a color octet quark-antiquark pair. The transition to the high-temperature state proceeds by the melting of this condensate. Quarks and gluons become (approximately) massless at the same critical temperature. For instanton-dominated effective multiquark interactions and three light quarks with equal mass we find a first order phase transition at a critical temperature around 170 MeV.

We investigate the allowed regions in the observable space of $\overrightarrow{B}\pi K,$ $B_d\to {\pi }^{+}{\pi }^{-},$ and $B_s\to K^{+}{K}^{-}$ decays, characterizing these modes in the standard model. After a discussion of a new kind of contour plot for the $\overrightarrow{B}\pi K$ system, we focus on the mixing-induced and direct $\mathrm{CP}$ asymmetries of the decays $B_d\to {\pi }^{+}{\pi }^{-}$ and $B_s\to K^{+}{K}^{-}.$ Using experimental information on the CP-averaged $B_d\to {\pi }^{\mp }{K}^{\pm }$ and $B_d\to {\pi }^{+}{\pi }^{-}$ branching ratios, the relevant hadronic penguin parameters can be constrained, implying certain allowed regions in observable space. In the case of $B_d\to {\pi }^{+}{\pi }^{-},$ an interesting situation arises now in view of the recent B-factory measurements of $\mathrm{CP}$ violation in this channel, allowing us to obtain new constraints on the CKM angle $\gamma$ as a function of the $B_d^0-\overline{B_d^0}$ mixing phase ${\phi }_d=2\mathrm{}\beta ,$ which is fixed through ${\mathcal{A}}_{\mathrm{CP}}^{\mathrm{mix}}{(B}_d\to J/\psi K_S)$ up to a twofold ambiguity. If we assume that ${\mathcal{A}}_{\mathrm{CP}}^{\mathrm{mix}}{(B}_d\to {\pi }^{+}{\pi }^{-})$ is positive, as indicated by recent Belle data, and that ${\phi }_d$ is in agreement with the “indirect” fits of the unitarity triangle, also the corresponding values for $\gamma$ around $60°$ can be accommodated. On the other hand, for the second solution of ${\phi }_d,$ we obtain a gap around $\gamma \sim 60°.$ The allowed region in the space of ${\mathcal{A}}_{\mathrm{CP}}^{\mathrm{mix}}{(B}_s\to K^{+}{K}^{-})$ and ${\mathcal{A}}_{\mathrm{CP}}^{\mathrm{dir}}{(B}_s\to K^{+}{K}^{-})$ is very constrained in the standard model, thereby providing a narrow target range for run II of the Fermilab Tevatron and the experiments of the CERN LHC era.

In view of recent neutrino experimental results such as SNO, Super-Kamiokande (SK), CHOOZ and neutrinoless double beta decay $\left(\beta {\beta }_{0\nu }\right),$ we consider a texture of neutrino mass matrix which contains three parameters in order to explain those neutrino experimental results. We first fitted the parameters in a model independent way with solar and atmospheric neutrino mass squared differences and a solar neutrino mixing angle which satisfies the LMA solution. The maximal value of the atmospheric neutrino mixing angle comes out naturally in the present texture. Most interestingly, the fitted parameters of the neutrino mass matrix considered here also marginally satisfy the recent limit on the effective Majorana neutrino mass obtained from the neutrinoless double beta decay experiment. We further demonstrate an explicit model which gives rise to the texture investigated by considering an ${\mathrm{SU}\left(2\right)\mathrm{}}_L\times {U\left(1\right)\mathrm{}}_Y$ gauge group with two extra real scalar singlets and a discrete $Z_2\times Z_3$ symmetry. Majorana neutrino masses are generated through higher dimensional operators at the scale M. We have estimated the scales at which singlets get VEV’s and M by comparing with the best fitted results obtained in the present work.

All possible Bogoliubov operators that generate the thermal transformations in thermo field dynamics form an $\mathrm{SU}(1,1)\mathrm{}$ group. We discuss this construction in the bosonic string theory. In particular, the transformation of the Fock space and string operators generated by the most general $\mathrm{SU}(1,1)\mathrm{}$ unitary Bogoliubov transformation and the entropy of the corresponding thermal string are computed. Also, we construct the thermal D-brane generated by the $\mathrm{SU}(1,1)\mathrm{}$ transformation in a constant Kalb-Ramond field and compute its entropy.

We investigate the apparent horizon formation for high-energy head-on collisions of particles in D-dimensional spacetime. The apparent horizons formed before the instant of collision are obtained analytically. We apply the D-dimensional hoop conjecture to these solutions and show that the horizon formation becomes more difficult for larger D.

We study the stability properties of the Kidder-Scheel-Teukolsky (KST) many-parameter formulation of Einstein’s equations for weak gravitational waves on flat space-time from a continuum and numerical point of view. At the continuum, performing a linearized analysis of the equations around flat space-time, it turns out that they have, essentially, no non-principal terms. As a consequence, in the weak field limit the stability properties of this formulation depend only on the level of hyperbolicity of the system. At the discrete level we present some simple one-dimensional simulations using the KST family. The goal is to analyze the type of instabilities that appear as one changes parameter values in the formulation. Lessons learned in this analysis can be applied in other formulations with similar properties.

We study the prospects for three-dimensional mapping of dark matter to high redshift through the shearing of faint galaxies images at multiple distances by gravitational lensing. Such maps could provide invaluable information on the nature of the dark energy and dark matter. While in principle well posed, mapping by direct inversion introduces exceedingly large, but usefully correlated noise into the reconstruction. By carefully propagating the noise covariance, we show that lensing contains substantial information, both direct and statistical, on the large-scale radial evolution of the density field. This information can be efficiently distilled into low-order signal-to-noise eigenmodes which may be used to compress the data by over an order of magnitude. Such compression will be useful for the statistical analysis of future large data sets. The reconstructed map also contains useful information on the localization of individual massive dark matter halos, and hence the dark energy from halo number counts, but its extraction depends strongly on prior assumptions. We outline a procedure for maximum entropy and point-source regularization of the maps that can identify alternate reconstructions.

There is growing observational evidence for a population of supermassive black holes (SMBHs) in galactic bulges. We examine in detail the conditions under which these black holes must have originated from primordial black holes (PBHs). We consider the merging and accretion history experienced by SMBHs to find that, whereas it is possible that they were formed by purely astrophysical processes, this is unlikely and most probably a population of primordial progenitors is necessary. We identify the mass distribution and comoving density of this population and then propose a cosmological scenario producing PBHs with the right properties. Although this is not essential we consider PBHs produced at the end of a period of inflation with a blue spectrum of fluctuations. We constrain the value of the spectral tilt in order to obtain the required PBH comoving density. We then assume that PBHs grow by accreting quintessence, showing that their mass scales like the horizon mass while the quintessence field itself is scaling. We find that if scaling is broken just before nucleosynthesis (as is the case with some attractive nonminimally coupled models) we obtain the appropriate PBH mass distribution. Hawking evaporation is negligible in most cases, but we also discuss situations in which the interplay of accretion and evaporation is relevant.

We study decay distributions in $\overrightarrow{B}K\pi \pi \gamma ,$ combining contributions from several overlapping resonances in a $K\pi \pi$ mass range near 1400 MeV, $1^{+}$ $K_1\mathrm{}\left(1400\right),$ $2^{+}$ $K_2^{*}\mathrm{}\left(1430\right)\mathrm{}$ and $1^{-}$ $K^{*}\mathrm{}\left(1410\right).$ A method is proposed for using these distributions to determine a photon polarization parameter in the effective radiative weak Hamiltonian. This parameter is measured through an up-down asymmetry of the photon direction relative to the $K\pi \pi$ decay plane in the $K_{\mathrm{res}}$ frame. We calculate a dominant up-down asymmetry of $0.33\pm 0.05$ from the $K_1\mathrm{}\left(1400\right)\mathrm{}$ resonance, which can be measured with about ${10}^8$ $B\overline{B}$ pairs, thus providing a new test for the standard model and a probe for some of its extensions.