Theory for computing the field scattered from a smooth inflected surface

A theory is described for computing the reflected or scattered field from a smooth body with inflection points. These inflections occur in certain directions at each surface point for which the total (Gaussian) curvature is zero or negative. For surface illumination in one of these critical directions, the usual reflection formulas obtained by the high-frequency approximation are inapplicable, and a shadow zone exists in the reflected field. Scattering into the shadow zone is treated, as well as specular reflection. This theory should have a variety of applications such as for certain optics problems, computer graphics modeling of three-dimensional shapes, and the design and analysis of specialized microwave reflector antennas

The Number Density of Intermediate and High Luminosity Active Galactic Nuclei at z~2-3

We use the combination of the 2 Ms Chandra X-ray image, new J and H band images, and the Spitzer IRAC and MIPS images of the Chandra Deep Field-North to obtain high spectroscopic and photometric redshift completeness of high and intermediate X-ray luminosity sources in the redshift interval z=2-3. We measure the number densities of z=2-3 active galactic nuclei (AGNs) and broad-line AGNs in the rest-frame 2-8 keV luminosity intervals 10^44-10^45 and 10^43-10^44 ergs/s and compare with previous lower redshift results. We confirm a decline in the number densities of intermediate-luminosity sources at z>1. We also measure the number density of z=2-3 AGNs in the luminosity interval 10^43-10^44.5 ergs/s and compare with previous low and high-redshift results. Again, we find a decline in the number densities at z>1. In both cases, we can rule out the hypothesis that the number densities remain flat to z=2-3 at above the 5-sigma level.Comment: 8 pages, Accepted by The Astrophysical Journal (scheduled for 10 Dec 2005

Breaking Eight-fold Degeneracies in Neutrino CP Violation, Mixing, and Mass Hierarchy

We identify three independent two-fold parameter degeneracies (\delta, \theta_{13}), sgn(\delta m^2_{31}) and (\theta_{23}, \pi/2-\theta_{23}) inherent in the usual three-neutrino analysis of long-baseline neutrino experiments, which can lead to as much as an eight-fold degeneracy in the determination of the oscillation parameters. We discuss the implications these degeneracies have for detecting CP violation and present criteria for breaking them. A superbeam facility with a baseline at least as long as the distance between Fermilab and Homestake (1290 km) and a narrow band beam with energy tuned so that the measurements are performed at the first oscillation peak can resolve all the ambiguities other than the (\theta_{23}, \pi/2-\theta_{23}) ambiguity (which can be resolved at a neutrino factory) and a residual (\delta, \pi-\delta) ambiguity. However, whether or not CP violation occurs in the neutrino sector can be ascertained independently of the latter two ambiguities. The (\delta,\pi-\delta) ambiguity can be eliminated by performing a second measurement to which only the \cos\delta terms contribute. The hierarchy of mass eigenstates can be determined at other oscillation peaks only in the most optimistic conditions, making it necessary to use the first oscillation maximum. We show that the degeneracies may severely compromise the ability of the proposed SuperJHF-HyperKamiokande experiment to establish CP violation. In our calculations we use approximate analytic expressions for oscillation probabilitites that agree with numerical solutions with a realistic Earth density profile.Comment: Revtex (singlespaced), 35 pages, 15 postscript figures, uses psfig.st

Matter profile effect in neutrino factory

We point out that the matter profile effect --- the effect of matter density fluctuation on the baseline --- is very important to estimate the parameters in a neutrino factory with a very long baseline. To make it clear, we propose the method of the Fourier series expansion of the matter profile. By using this method, we can take account of both the matter profile effect and its ambiguity. For very long baseline experiment, such as L=7332km, in the analysis of the oscillation phenomena we need to introduce a new parameter $a_{1}$--- the Fourier coefficient of the matter profile --- as a theoretical parameter to deal with the matter profile effects.Comment: 21 pages, 15 figure

Searching for a heavy Higgs boson via the H --> l nu jj decay mode at the CERN LHC

The discovery of a heavy Higgs boson with mass up to m_H = 1 TeV at the CERN LHC is possible in the H--> W^+W^- --> l nu jj decay mode. The weak boson scattering signal and backgrounds from t\bar tjj and from W+jets production are analyzed with parton level Monte Carlo programs which are built on full tree level amplitudes for all subprocesses. The use of double jet tagging and the reconstruction of the W invariant mass reduce the combined backgrounds to the same level as the Higgs signal. A central mini-jet veto, which distinguishes the different gluon radiation patterns of the hard processes, further improves the signal to background ratio to about 2.5:1, with a signal cross section of 1 fb. The jet energy asymmetry of the W --> jj decay will give a clear signature of the longitudinal polarization of the W's in the final event sample.Comment: 23 pages (with 7 embedded figures), Revtex, uses epsf.sty. Z-compressed postscript version also available at http://phenom.physics.wisc.edu/pub/preprints/1997/madph-97-1017.ps.Z or at ftp://phenom.physics.wisc.edu/pub/preprints/1997/madph-97-1017.ps.

Search for Top Quark FCNC Couplings in Z' Models at the LHC and CLIC

The top quark is the heaviest particle to date discovered, with a mass close to the electroweak symmetry breaking scale. It is expected that the top quark would be sensitive to the new physics at the TeV scale. One of the most important aspects of the top quark physics can be the investigation of the possible anomalous couplings. Here, we study the top quark flavor changing neutral current (FCNC) couplings via the extra gauge boson Z' at the Large Hadron Collider (LHC) and the Compact Linear Collider (CLIC) energies. We calculate the total cross sections for the signal and the corresponding Standard Model (SM) background processes. For an FCNC mixing parameter x=0.2 and the sequential Z' mass of 1 TeV, we find the single top quark FCNC production cross sections 0.38(1.76) fb at the LHC with sqrt{s_{pp}}=7(14) TeV, respectively. For the resonance production of sequential Z' boson and decays to single top quark at the Compact Linear Collider (CLIC) energies, including the initial state radiation and beamstrahlung effects, we find the cross section 27.96(0.91) fb at sqrt{s_{e^{+}e^{-}}}=1(3) TeV, respectively. We make the analysis to investigate the parameter space (mixing-mass) through various Z' models. It is shown that the results benefit from the flavor tagging.Comment: 20 pages, 17 figures, 6 table

Production of Z^0 bosons with rapidity gaps: exclusive photoproduction in gamma p and p p collisions and inclusive double diffractive Z^0's

We extend the k_\perp-factorization formalism for exclusive photoproduction of vector mesons to the production of electroweak Z^0 bosons. Predictions for the gamma p \to Z^0 p and p p \to p p Z^0 reactions are given using an unintegrated gluon distribution tested against deep inelastic data. We present distributions in the Z^0 rapidity, transverse momentum of Z^0 as well as in relative azimuthal angle between outgoing protons. The contributions of different flavours are discussed. Absorption effects lower the cross section by a factor of 1.5-2, depending on the Z-boson rapidity. We also discuss the production of Z^0 bosons in central inclusive production. Here rapidity and (x_{\Pom,1}, x_{\Pom,2}) distributions of Z^0 are calculated. The corresponding cross section is about three orders of magnitude larger than that for the purely exclusive process.Comment: 19 pages, 14 figs, A. Cisek is married name of A. Rybarsk

Progress in the physics of massive neutrinos

The current status of the physics of massive neutrinos is reviewed with a forward-looking emphasis. The article begins with the general phenomenology of neutrino oscillations in vacuum and matter and documents the experimental evidence for oscillations of solar, reactor, atmospheric and accelerator neutrinos. Both active and sterile oscillation possibilities are considered. The impact of cosmology (BBN, CMB, leptogenesis) and astrophysics (supernovae, highest energy cosmic rays) on neutrino observables and vice versa, is evaluated. The predictions of grand unified, radiative and other models of neutrino mass are discussed. Ways of determining the unknown parameters of three-neutrino oscillations are assessed, taking into account eight-fold degeneracies in parameters that yield the same oscillation probabilities, as well as ways to determine the absolute neutrino mass scale (from beta-decay, neutrinoless double-beta decay, large scale structure and Z-bursts). Critical unknowns at present are the amplitude of \nu_\mu to \nu_e oscillations and the hierarchy of the neutrino mass spectrum; the detection of CP violation in the neutrino sector depends on these and on an unknown phase. The estimated neutrino parameter sensitivities at future facilities (reactors, superbeams, neutrino factories) are given. The overall agenda of a future neutrino physics program to construct a bottom-up understanding of the lepton sector is presented.Comment: 111 pages, 35 figures. Update

Search for Exotic Muon Decays

Recently, it has been proposed that the observed anomaly in the time distribution of neutrino induced reactions, reported by the KARMEN collaboration, can be interpreted as a signal from an exotic muon decay branch mu+ to e+ X. It has been shown that this hypothesis gives an acceptable fit to the KARMEN data if the boson X has a mass of m_X=103.9MeV/c^2, close to the kinematical limit. We have performed a search for the X particle by studying for the first time the very low energy part of the Michel spectrum in mu+ decays. Using a HPGe detector setup at the muE4 beamline at PSI we find branching ratios BR(mu+ to e+ X)<5.7e-4 (90% C.L.) for most of the region 103MeV/c^2<m_X<105MeV/c^2.Comment: 9 page