18,063 research outputs found

    Report on the first binary black hole inspiral search in LIGO data

    Full text link
    The LIGO Scientific Collaboration is currently engaged in the first search for binary black hole inspiral signals in real data. We are using the data from the second LIGO science run and we focus on inspiral signals coming from binary systems with component masses between 3 and 20 solar masses. We describe the analysis methods used and report on preliminary estimates for the sensitivities of the LIGO instruments during the second science run.Comment: 10 pages, 2 figures. Added references for section 2, corrected figure 1. To appear in CQG, in a special issue on the proceedings of the 9th Annual Gravitational Wave Data Analysis Workshop (GWDAW), Annecy, France, Dec. 200

    Increased Yield of ttbb at Hadron Colliders in Low-Energy Supersymmetry

    Get PDF
    Light bottom squarks and gluinos have been invoked to explain the b quark pair production excess at the Tevatron. We investigate the associated production of ttbb at hadron colliders in this scenario, and find that the rates for this process are enhanced over the Standard Model prediction. If light gluinos exist, it may be possible to detect them at the Tevatron, and they could easily be observed at the LHC.Comment: 5p, references added, version accepted to PR

    Sol-Gel Derived Ferroelectric Nanoparticles Investigated by Piezoresponse Force Microscopy

    Full text link
    Piezoresponse force microscopy (PFM) was used to investigate the ferroelectric properties of sol-gel derived LiNbO3_3 nanoparticles. To determine the degree of ferroelectricity we took large-area images and performed statistical image-analysis. The ferroelectric behavior of single nanoparticles was verified by poling experiments using the PFM tip. Finally we carried out simultaneous measurements of the in-plane and the out-of-plane piezoresponse of the nanoparticles, followed by measurements of the same area after rotation of the sample by 90^{\circ} and 180^{\circ}. Such measurements basically allow to determine the direction of polarization of every single particle

    Complementarity and Chiral Fermions in SU(2) gauge Theories

    Full text link
    Complementarity - the absence of a phase boundary separating the Higgs and confinement phases of a gauge theory - can be violated by the addition of chiral fermions. We utilize chiral symmetry violating fermion correlators such as \langle \bps \psi \rangle as order parameters to investigate this issue. Using inequalities similar to those of Vafa-Witten and Weingarten, we show that SU(2) gauge theories with Higgs and fermion fields in the fundamental representation exhibit chiral symmetry breaking in the confined phase and therefore do {\it not} lead to massless composite fermions. We discuss the implications for the Abbott-Farhi strongly interacting standard model.Comment: 10 pages, HUTP-92-A047, 2 figures not include

    Effects of the R-parity violation in the minimal supersymmetric standard model on dilepton pair production at the CERN LHC

    Get PDF
    We investigate in detail the effects of the R-parity lepton number violation in the minimal supersymmetric standard model (MSSM) on the parent process ppe+e+Xpp \to e^+ e^- + X at the CERN Large Hadron Collider (LHC). The numerical comparisons between the contributions of the R-parity violating effects to the parent process via the Drell-Yan subprocess and the gluon-gluon fusion are made. We find that the R-violating effects on e+ee^+ e^- pair production at the LHC could be significant. The results show that the cross section of the e+e e^+ e^- pair productions via gluon-gluon collision at the LHC can be of the order of 10210^2 fb, and this subprocess maybe competitive with the production mechanism via the Drell-Yan subprocess. We give also quantitatively the analysis of the effects from both the mass of sneutrino and coupling strength of the R-parity violating interactions.Comment: 18 pages, 10 figures, accepted by Phys. Rev.

    Searches for Gravitational Waves from Binary Neutron Stars: A Review

    Full text link
    A new generation of observatories is looking for gravitational waves. These waves, emitted by highly relativistic systems, will open a new window for ob- servation of the cosmos when they are detected. Among the most promising sources of gravitational waves for these observatories are compact binaries in the final min- utes before coalescence. In this article, we review in brief interferometric searches for gravitational waves emitted by neutron star binaries, including the theory, instru- mentation and methods. No detections have been made to date. However, the best direct observational limits on coalescence rates have been set, and instrumentation and analysis methods continue to be refined toward the ultimate goal of defining the new field of gravitational wave astronomy.Comment: 30 pages, 5 Figures, to appear in "Short-Period Binary Stars: Observations, Analyses, and Results", Ed.s Eugene F. Milone, Denis A. Leahy, David W. Hobil

    Elastic Instability Triggered Pattern Formation

    Get PDF
    Recent experiments have exploited elastic instabilities in membranes to create complex patterns. However, the rational design of such structures poses many challenges, as they are products of nonlinear elastic behavior. We pose a simple model for determining the orientational order of such patterns using only linear elasticity theory which correctly predicts the outcomes of several experiments. Each element of the pattern is modeled by a "dislocation dipole" located at a point on a lattice, which then interacts elastically with all other dipoles in the system. We explicitly consider a membrane with a square lattice of circular holes under uniform compression and examine the changes in morphology as it is allowed to relax in a specified direction.Comment: 15 pages, 7 figures, the full catastroph
    corecore