Measurements of the cosmic-ray hydrogen and helium spectra at energies from 20 to 800 TeV are presented. The experiments were performed on a series of twelve balloon Ñights, including several long duration Australia to South America and Antarctic circumpolar Ñights. No clear evidence is seen for a spectral break. Both the hydrogen and the helium spectra are consistent with power laws over the entire energy range, with integral spectral indices 1.80^0.04 and for the protons and helium, respec-1.68~0 .06 0.04 tively. The results are fully consistent with expectations based on supernova shock acceleration coupled with a "" leaky box ÏÏ model of propagation through the Galaxy.
We study hadron properties near the deconfining transition in the quenched lattice QCD simulation. This paper focuses on the heavy quarkonium states, such as J/ψ meson. In order to treat heavy quarks at T > 0, we adopt the O(a) improved Wilson action on anisotropic lattice. We discuss cc bound state observing the wave function and compare the meson correlators at above and below T c . Although we find a large change of correlator near the T c , the strong spatial correlation which is almost the same as confinement phase survives even T ∼ 1.5T c .
The mass shift of charmonium near the critical temperature of the deconfining transition is investigated by a c-c potential model through the change of the string tension. On the basis of the results, detection of the shift by lepton-pair production is discussed by the use of the hydrodynamical model of ultrarelativistic nucleus-nucleus collisions. It is shown that the mass shift is detectable if the critical temperature is not lower than 300 MeV. PACS numbers: 12.38.Mh, 12.40.Ee, 12.40.Qq, 25.70.Np Although there has been increasing support for the existence of deconfinement and/or chiral restoring transitions at finite temperature or high density in theoretical 1 and numerical 2 investigations, the possibility of detection of these transitions and the new phases is not yet clear. 3 On this problem, the hadronic mass shift related to the restoration of chiral symmetry has been discussed recently. 4,5 Despite the uniqueness of the phenomenon, detectability of the effect in actual collisions is still uncertain. In this Letter, we present some results for the mass shift of charmonium and the change of its leptonic width with variation of string tension, which is expected to be temperature dependent. Recent works in Monte Carlo simulation 6 " 8 and model investigation 9 ' 10 suggest critical behavior of the string tension near the deconfining transition. Further, we discuss detection of the mass shift by leptonpair production in heavy-ion collisions based on hydrodynamical development. 11 " 13 We see that the effect could be detectable if the deconfining temperature is not lower than 300 MeV.The computation of the mass shift adopted here is based on the c-c potential modelwhere the first term is the gluon-exchange Coulombic term given by Buchmuller and Tye, 14 i.e., with A = 250 MeV and b Q -9 (three flavors).Since we consider the string tension k at finite temperature, our present interest is to solve for c-c states under variation of k. Generally speaking, the Coulombic term might also be temperature dependent. Here we restrict ourselves to variation of the string tension, because the long-range part, kr, would primarily show a finite-temperature effect below the critical temperature. The mass of the charm quark in the potential model may also be temperature dependent. In the case of heavy quarks, this would be a minor effect and is omitted in the present calculation. We shall comment further on this in later discussions.Calculations are made by a variational method with variation of the string tension. In the calculation of the leptonic width, the reliability of the value of the variational wave function at the origin is rather poor. So we adopt the values from the sum rule for the potential, i.e., l^(0)| 2 =(/^/27r)
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