نتایج جستجو برای: gev
تعداد نتایج: 18737 فیلتر نتایج به سال:
Upper limits are given on the production of unstable neutral leptons in electron-positron annihilation at 29 GeV. The searches use selected 2 and 4 charged particle events and are most sensitive to neutral lepton masses of the order of 1 GeV/c2 and smaller. However results are given for masses up to 14 GeV/c2.
The study of low-angle and large-angle Bhabha scattering at LEP gives access to the running of the electromagnetic coupling. Two recent measurements of the OPAL and L3 collaborations probe the running of α in the regions 1.8 GeV < −Q < 6.1 GeV and 1800 GeV < −Q < 21600 GeV, respectively. The strategies and the results of these studies are presented. A global overview is given of the agreement o...
The phase transition in the Weinberg-Salam-Glashow (GSW) electroweak theory extended by the majoron and dilaton field is considered. The possibility of the boson condensation in the extreme conditions in the standard electroweak theory is shown. The first order phase transition induces by the radiative corrections (the Coleman-Weinberg potential) in the presence of matter was considered. Due to...
In 2001, PHENIX measured particle correlations of identical charged pions and kaons at mid-rapidity in Au-Au collisions at √ s N N = 200 GeV. Bertsch-Pratt radius parameters of pion pairs are studied for 9 k T regions from 0.2 to 2.0 GeV/c and for 9 selections of collision centralities. The pion radius parameters are consistent with the result at √ s N N = 130 GeV, and the ratio R out /R side i...
The analysing power AN is examined in the range of the Coulomb-hadron interference on the basis of the experimental data from pL = 6 GeV/c up to 200 GeV/c taking account of a phenomenological analysis at pL = 6 GeV/c and a dynamic high-energy spin model. The results are compared with the new RHIC data at pL = 100 GeV/c. The new experimental data obtained at RHIC indicate small contributions of ...
We present a study on the spectra for heavy flavor (charm and bottom) decayed electrons in 200 GeV p+p collisions and provide the relative contributions of charm and bottom hadrons from the PYTHIA calculations. The results suggest that the crossing point of the electron spectra from charm and bottom decays is above 7 GeV/c and bottom contribution is not dominant for electron pT < 3 GeV/c. The u...
The production of hyperons in Pb-Pb and p-Be interaction at 40 A GeV/c beam momentum has been measured by the NA57 experiment. Strange particle enhancements at 40 A GeV/c are presented for the first time and compared to those measured at 158 A GeV/c. The transverse mass spectra of high statistics, high purity samples of K 0 S , Λ, Ξ and Ω particles produced in Pb-Pb collisions at 158 A GeV/c ha...
The analysing power A N is examined in the range of the Coulomb-hadron interferenceon on the basis of the experimental data from p L = 6 GeV /c up to 200 GeV /c taking account of a phenomenological analysis at p L = 6 GeV /c and a dynamic high-energy spin model. The results are compared with the new RHIC data at p L = 100 GeV /c. The new experimental data obtained at RHIC indicate the small con...
The masses, total widths, and leptonic widths of three triplet s-wave bb states Y(4S), Y (5S), and Y(6S) are determined from measurements of the e+e annihilation cross section into hadrons for 10.55 & W & 11.25 GeV. The resonances are identified from potential model results and their properties are obtained with the help of a simplified coupled-channels calculation. We find M(4S) = 10.577 GeV, ...
The study of Bhabha scattering at ee colliders probes the running of the electromagnetic coupling. After early measurements by the VENUS collaboration at TRISTAN and the by L3 collaboration at LEP, two recent analyses have been performed by the OPAL and L3 collaborations. The OPAL collaboration studied highstatistics low-angle Bhabha scattering at LEP, achieving a precise determination of the r...
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