415 research outputs found

    Scanning of the e+e- to pi+pi- cross--section below 1 GeV by radiative events with untagged photon

    Full text link
    We discuss an inclusive approach to the measurement of the e+e- --> pi+ pi- cross--section by the radiative return method without photon tagging. The essential part of this approach is the choice of rules for event selection which provide rejection of events with 3 (or more) pions and decrease the final--state radiation background. The radiative corrections to the initial--state radiation process are computed for DAPhNE conditions, using the quasi--real electron approximation for both, the cross--section and the underlying kinematics. The two cases of restricted and unrestricted pion phase space are considered. Some numerical calculations illustrate our analytical results.Comment: 25 pages, 4 figures, late

    Radiative Corrections to the Hadronic Cross-Section Measurement at DAPHNE

    Get PDF
    The hadronic invariant mass distribution for the process of electron-positron annihilation into a pair of charged pions accompanied by a photon radiated from the initial state has been studied for the region of DAΦ\PhiNE energies. The Born cross-section and the electromagnetic radiative corrections to it are calculated for realistic conditions of the KLOE detector. The dependence on the physical parameters which define the event selection is obtained.Comment: 15 pages, Latex, 21 references, no figure

    Hadronic Total Cross-sections Through Soft Gluon Summation in Impact Parameter Space

    Get PDF
    The Bloch-Nordsieck model for the parton distribution of hadrons in impact parameter space, constructed using soft gluon summation, is investigated in detail. Its dependence upon the infrared structure of the strong coupling constant αs\alpha_s is discussed, both for finite as well as singular, but integrable, αs\alpha_s. The formalism is applied to the prediction of total proton-proton and proton-antiproton cross-sections, where screening, due to soft gluon emission from the initial valence quarks, becomes evident.Comment: 20 pages, Latex2e, input FEYNMAN,12 postscipt figures. Submitted to PR

    Hadronic Equipartition of Quark and Glue Momenta

    Get PDF
    If the ``glue'' which binds quarks within hadrons takes the form of strings, then a virial theorem may be derived which shows how the total hadron four momentum splits up into a quark contribution plus a glue contribution. The hadrons made up of light quarks exhibit an equipartion of four momentum into equal parts quarks and glue. The agreement with the experimental ``parton'' distribution four momentum sum rule is quite satisfactory as is the string fragmentation model.Comment: four pages, RevTeX format, one figure *.ep

    Adhesion State Estimation for Electrostatic Gripper Based on Online Capacitance Measure

    Get PDF
    Electroadhesion is a suitable technology for developing grippers for applications where fragile, compliant or variable shape objects need to be grabbed and where a retention action is typically preferred to a compression force. This article presents a self-sensing technique for electroadhesive devices (EAD) based on the capacitance measure. Specifically, we demonstrate that measuring the variation of the capacitance between electrodes of an EAD during the adhesion can provide useful information to automatically detect the successful grip of an object and the possible loss of adhesion during manipulation. To this aim, a dedicated electronic circuit is developed that is able to measure capacitance variations while the high voltage required for the adhesion is activated. A test bench characterization is presented to evaluate the self-sensing of capacitance during different states: (1) the EAD is far away from the object to be grasped; (2) the EAD is in contact with the object, but the voltage is not active (i.e., no adhesion); and (3) the EAD is activated and attached to the object. Correlation between the applied voltage, object material and shape and capacitance is made. The self-sensing EAD is then demonstrated in a closed-loop robotic application that employs a robot manipulator arm to pick and place objects of different kinds

    A Wireless, Battery-Powered Probe Based on a Dual-Tier CMOS SPAD Array for Charged Particle Sensing

    Get PDF
    A compact probe for charged particle imaging, with potential applications in source activity mapping and radio-guided surgery was designed and tested. The development of this technology holds significant implications for medical imaging, offering healthcare professionals accurate and efficient tools for diagnoses and treatments. To fulfill the portability requirements of these applications, the probe was designed for battery operation and wireless communication with a PC. The core sensor is a dual-layer CMOS SPAD detector, fabricated using 150 nm technology, which uses overlapping cells to produce a coincidence signal and reduce the dark count rate (DCR). The sensor is managed and interfaced with a microcontroller, and custom firmware was developed to facilitate communication with the sensor. The performance of the probe was evaluated by characterizing the on-board SPAD detector in terms of the DCR, and the results were consistent with the characterization measurements taken on the same chip samples using a purposely developed benchtop setup

    QCD Corrections to Toponium Production at Hadron Colliders

    Full text link
    Toponium production at future hadron colliders is investigated. Perturbative QCD corrections to the production cross section for gluon fusion are calculated as well as the contributions from gluon-quark and quark-antiquark collisions to the total cross section. The dependence on the renormalization and factorization scales and on the choice of the parton distribution functions is explored. QCD corrections to the branching ratio of ηt\eta_{t} into γγ\gamma\gamma are included and the two-loop QCD potential is used to predict the wave function at the origin. The branching ratio of ηt\eta_{t} into γZ\gamma Z, ZZZZ, HZHZ and WWWW is compared with the γγ\gamma\gamma channel.Comment: 16 pages (latex) 9 figures (postscript) available upon request, TTP92-3
    corecore