Search results for "scattering [electron hadron]"
showing 10 items of 654 documents
Strange meson production at high density and temperature
2010
The properties of strange mesons ($K$, $\bar K$ and $\bar K^*$) in dense matter are studied using a unitary approach in coupled channels for meson-baryon scattering. The kaon-nucleon interaction incorporates $s$- and $p$-wave contributions within a chiral model whereas the interaction of $\bar K^*$ with nucleons is obtained in the framework of the local hidden gauge formalism. The in-medium solution for the scattering amplitude accounts for Pauli blocking effects, mean-field binding on baryons, and meson self-energies. We obtain the $K$, $\bar K$ and $\bar K^*$ (off-shell) spectral functions in the nuclear medium and study their behaviour at finite density, temperature and momentum. We also…
Search for charged massive long-lived particles
2012
We report on a search for charged massive long-lived particles (CMLLPs), based on 5.2 fb$^{-1}$ of integrated luminosity collected with the D0 detector at the Fermilab Tevatron $p\bar{p}$ collider. We search for events in which one or more particles are reconstructed as muons but have speed and ionization energy loss $(dE/dx)$ inconsistent with muons produced in beam collisions. CMLLPs are predicted in several theories of physics beyond the standard model. We exclude pair-produced long-lived gaugino-like charginos below 267 GeV and higgsino-like charginos below 217 GeV at 95% C.L., as well as long-lived scalar top quarks with mass below 285 GeV.
Search for Randall-Sundrum gravitons in dilepton and diphoton final states
2005
We report the first direct search for the Kaluza-Klein (KK) modes of Randall-Sundrum gravitons using dielectron, dimuon, and diphoton events observed with the D0 detector operating at the Fermilab Tevatron ppbar Collider at sqrt(s) = 1.96 TeV. No evidence for resonant production of gravitons has been found in the data corresponding to an integrated luminosity of approximately 260 pb^-1. Lower limits on the mass of the first KK mode at the 95% C.L. have been set between 250 and 785 GeV, depending on its coupling to SM particles.
Search for new fermions ("quirks") at the Fermilab Tevatron Collider
2010
We report results of a search for particles with anomalously high ionization in events with a high transverse energy jet and large missing transverse energy in $2.4$ fb$^{-1}$ of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron $p\bar{p}$ collider. Production of such particles (quirks) is expected in scenarios with extra QCD-like {\it SU(N)} sectors, and this study is the first dedicated search for such signatures. We find no evidence of a signal and set a lower mass limit of 107 ~GeV for the mass of a charged quirk with strong dynamics scale $\Lambda$ in the range from 10 keV to 1 MeV.
Rosenbluth Separation of the π^{0} Electroproduction Cross Section.
2016
We present deeply virtual $\pi^0$ electroproduction cross-section measurements at $x_B$=0.36 and three different $Q^2$--values ranging from 1.5 to 2 GeV$^2$, obtained from experiment E07-007 that ran in the Hall A at Jefferson Lab. The Rosenbluth technique was used to separate the longitudinal and transverse responses. Results demonstrate that the cross section is dominated by its transverse component, and thus is far from the asymptotic limit predicted by perturbative Quantum Chromodynamics. An indication of a non-zero longitudinal contribution is provided by the interference term $\sigma_{LT}$ also measured. Results are compared with several models based on the leading twist approach of G…
Search for large extra spatial dimensions in dimuon production with the D0 detector
2005
We present the results of a search for the effects of large extra spatial dimensions in $p{\bar p}$ collisions at $\sqrt{s} =$ 1.96 TeV in events containing a pair of energetic muons. The data correspond to 246 \ipb of integrated luminosity collected by the \D0 experiment at the Fermilab Tevatron Collider. Good agreement with the expected background was found, yielding no evidence for large extra dimensions. We set 95% C.L. lower limits on the fundamental Planck scale between 0.85 TeV and 1.27 TeV within several formalisms. These are the most stringent limits achieved in the dimuon channel to date.
Excitonic effects in two-LO-phonon resonant Raman scattering.
1993
Abstract The role of electron-hole correlation in resonant Raman scattering by two LO-phonons is analyzed. A theoretical model including excitons belonging to the discrete and continuous spectra as virtual intermediate states in the Raman process and valid for incident energies below and above the gap is developed. For the exciton-phonon coupling the Frohlich Hamiltonian is considered. The most important contribution to the Raman scattering efficiency corresponds to the continuous→discrete→discrete exciton transition, followed by the discrete→discrete→discrete and the continuous→continuous→discrete ones. The model is tested for GaP, where the scattering efficiency data are available around …
Transmission of light in deep sea water at the site of the Antares neutrino telescope
2005
The ANTARES neutrino telescope is a large photomultiplier array designed to detect neutrino-induced upward-going muons by their Cherenkov radiation. Understanding the absorption and scattering of light in the deep Mediterranean is fundamental to optimising the design and performance of the detector. This paper presents measurements of blue and UV light transmission at the ANTARES site taken between 1997 and 2000. The derived values for the scattering length and the angular distribution of particulate scattering were found to be highly correlated, and results are therefore presented in terms of an absorption length lambda_abs and an effective scattering length lambda_sct^eff. The values for …
Beam test measurements of Low Gain Avalanche Detector single pads and arrays for the ATLAS High Granularity Timing Detector
2018
For the high luminosity upgrade of the LHC at CERN, ATLAS is considering the addition of a High Granularity Timing Detector (HGTD) in front of the end cap and forward calorimeters at |z|= 3.5 m and covering the region 2.4 <|η|< 4 to help reducing the effect of pile-up. The chosen sensors are arrays of 50 μm thin Low Gain Avalanche Detectors (LGAD). This paper presents results on single LGAD sensors with a surface area of 1.3×1.3 mm2 and arrays with 2×2 pads with a surface area of 2×2 mm2 or 3×3 mm2 each and different implant doses of the p+ multiplication layer. They are obtained from data collected during a beam test campaign in autumn 2016 with a pion beam of 120 GeV energy at the CERN SP…
Relative luminosity measurement of the LHC with the ATLAS forward calorimeter
2010
In this paper it is shown that a measurement of the relative luminosity changes at the LHC may be obtained by analysing the currents drawn from the high voltage power supplies of the electromagnetic section of the forward calorimeter of the ATLAS detector. The method was verified with a reproduction of a small section of the ATLAS forward calorimeter using proton beams of known beam energies and variable intensities at the U-70 accelerator at IHEP in Protvino, Russia. The experimental setup and the data taking during a test beam run in April 2008 are described in detail. A comparison of the measured high voltage currents with reference measurements from beam intensity monitors shows a linea…