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81.
82.
Auerbach LB Burman RL Caldwell DO Church ED Cochran AK Donahue JB Fazely AR Garvey GT Gunasingha RM Imlay RL Kahrimanis G Louis WC Majkic R Malik A McIlhany KL Metcalf WJ Mills GB Rupnik D Sandberg VD Smith D Somodi RF Stancu I Strossman WD Sung M Tayloe R VanDalen GJ Vernon W Wadia N White DH Yellin S Yi H;LSND Collaboration 《Physical review letters》2004,92(9):091801
We observe a net beam excess of 8.7+/-6.3(stat)+/-2.4(syst) events, above 160 MeV, resulting from the charged-current reaction of nu(micro) and/or nu;(mu) on C and H in the LSND detector. No beam-related muon background is expected in this energy regime. Within an analysis framework of pi(0)-->nu(mu)nu;(mu), we set a direct upper limit for this branching ratio of Gamma(pi(0)-->nu(mu)nu;(mu))/Gamma(pi(0)-->all)<1.6 x 10(-6) at 90% confidence level. 相似文献
83.
Reisdorf W Andronic A Gobbi A Hartmann ON Herrmann N Hildenbrand KD Kim YJ Kirejczyk M Koczoń P Kress T Leifels Y Schüttauf A Tymiński Z Xiao ZG Alard JP Barret V Basrak Z Bastid N Benabderrahmane ML Caplar R Crochet P Dupieux P Dzelalija M Fodor Z Grishkin Y Hong B Kecskemeti J Korolija M Kotte R Lebedev A Lopez X Merschmeyer M Mösner J Neubert W Pelte D Petrovici M Rami F de Schauenburg B Seres Z Sikora B Sim KS Simion V Siwek-Wilczyńska K Smolyankin V Stockmeier M Stoicea G Wagner P 《Physical review letters》2004,92(23):232301
We present a complete systematics (excitation functions and system-size dependences) of global stopping and side flow for heavy ion reactions in the energy range between 0.09A and 1.93A GeV. For the heaviest system, Au+Au, we observe a plateau of maximal stopping extending from about 0.2A to 0.8A GeV with a fast drop on both sides. The degree of stopping, which is shown to remain significantly below the expectations of a full stopping scenario, is found to be highly correlated to the amount of side flow. 相似文献
84.
The H Collaboration 《The European Physical Journal C - Particles and Fields》2004,37(2):141-159
Triple differential dijet cross sections in
interactions are presented in the region of photon virtualities 2 < Q
2 < 80 GeV2, inelasticities 0.1 < y < 0.85, jet transverse energies E
*
T 1 > 7 GeV, E
*
T 2 > 5 GeV, and pseudorapidities
. The measurements are made in the
centre-of-mass frame, using an integrated luminosity of 57 pb-1. The data are compared with NLO QCD calculations and LO Monte Carlo programs with and without a resolved virtual photon contribution. NLO QCD calculations fail to describe the region of low Q
2 and low jet transverse energies, in contrast to a LO Monte Carlo generator which includes direct and resolved photon interactions with both transversely and longitudinally polarised photons. Initial and final state parton showers are tested as a mechanism for including higher order QCD effects in low E
T
jet production.Received: 13 January 2004, Revised: 21 July 2004, Published online: 18 August 2004 相似文献
85.
Approximately 438 pb-1 of e + e- data from the OPAL detector, taken with the LEP collider running at centre-of-mass energies of 192-209 GeV, are analyzed to search for evidence of chargino pair production,
, or neutralino associated production,
. Limits are set at the 95% confidence level on the product of the cross-section for the process
and its branching ratios to topologies containing jets and missing energy, or jets with a lepton and missing energy, and on the product of the cross-section for
and its branching ratio to jets. R-parity conservation is assumed throughout this paper. When these results are interpreted in the context of the Constrained Minimal Supersymmetric Standard Model, limits are also set on the masses of the
and
, and regions of the parameter space of the model are ruled out. Nearly model-independent limits are also set at the 95% confidence level on
with the assumption that each chargino decays via a W boson, and on
with the
assumed to decay via a Z0.Received: 15 December 2003, Revised: 16 February 2004, Published online: 23 April 2004 相似文献
86.
A second workshop on small-x physics, within the Small-x Collaboration, was held in Lund in June 2002 with the aim of over-viewing recent theoretical progress in this area and summarizing the experimental status.Received: 23 December 2003, Published online: 30 April 2004This paper is dedicated to the memory of Jan Kwieciski, who died unexpectedly on August 29, 2003. 相似文献
87.
Searches for neutral Higgs bosons produced at LEP in association with Z bosons, in pairs and in the Yukawa process are presented in this paper. Higgs boson decays into b quarks,
leptons, or other Higgs bosons are considered, giving rise to four-b, four-b + jets, six-b and four-
final states, as well as mixed modes with b quarks and
leptons. The whole mass domain kinematically accessible at LEP in these topologies is searched. The analysed data set covers both the LEP1 and LEP2 energy ranges and exploits most of the luminosity recorded by the DELPHI experiment. No convincing evidence for a signal is found, and results are presented in the form of mass-dependent upper bounds on coupling factors (in units of model-independent reference cross-sections) for all processes, allowing interpretation of the data in a large class of models.Received: 26 October 2003, Revised: 1 September 2004, Published online: 28 October 2004 相似文献
88.
The EDDA Collaboration 《The European Physical Journal A - Hadrons and Nuclei》2004,22(1):125-148
We have measured differential cross-sections for
elastic scattering with internal fiber targets in the recirculating beam of the proton synchrotron COSY. Measurements were made continuously during acceleration for projectile kinetic energies between 0.23 and 2.59 GeV in the angular range
. Details of the apparatus and the data analysis are given and the resulting excitation functions and angular distributions presented. The precision of each data point is typically better than 4%, and a relative normalization uncertainty of only 2.5% within an excitation function has been reached. The impact on phase shift analysis as well as upper bounds on possible resonant contributions in lower partial waves are discussed.Received: 24 March 2004, Published online: 19 October 2004PACS:
25.40.Cm Elastic proton scattering - 13.75.Cs Nucleon-nucleon interactions (including antinucleons, deuterons, etc.) - 13.85.Dz Elastic scattering - 21.30.-x Nuclear forces 相似文献
89.
Cross-sections and angular distributions for hadronic and lepton-pair final states in e + e- collisions at centre-of-mass energies between 189 GeV and 209 GeV, measured with the OPAL detector at LEP, are presented and compared with the predictions of the Standard Model. The measurements are used to determine the electromagnetic coupling constant
at LEP 2 energies. In addition, the results are used together with OPAL measurements at 91-183 GeV within the S-matrix formalism to determine the
-Z interference term and to make an almost model-independent measurement of the Z mass. Limits on extensions to the Standard Model described by effective four-fermion contact interactions or the addition of a heavy Z boson are also presented.Received: 28 August 2003, Published online: 18 February 2004 相似文献
90.
A resonance search has been made in the
invariant-mass spectrum with the ZEUS detector at HERA using an integrated luminosity of
. The decay channels
and
(and the corresponding antiparticle decays) were used to identify
mesons. No resonance structure was observed in the
mass spectrum from more than 60 000 reconstructed
mesons. The results are not compatible with a report of the H1 Collaboration of a charmed pentaquark,
.Received: 14 September 2004, Revised: 29 September 2004, Published online: 9 November 2004 相似文献