The experimental isoscalar → S-wave amplitude squared below 1.75 GeV is characterized by a very broad structure f 0 (400Ϫ1200) with two narrow dips due to its destructive interference with the f 0 (980) and f 0 (1500). The f 0 (1370) and f 0 (1710) do not show up clearly in the → S-wave amplitude due to their weak coupling to . This paper is about the controversial nature of the broad f 0 (400Ϫ1200). We decompose it into two parts, i.e., t-channel meson exchange plus an additional s-channel resonance f 0 (X). With the t-channel meson exchange fixed by the isotensor → S-wave scattering, we refit the CERN-Munich ͑CM͒ data on scattering to get parameters for the f 0 (X). We find that the f 0 (X) is very broad with a nearby pole at (1.67Ϫ0.26i) GeV, while the t-channel meson exchange part produces a pole at (0.36Ϫ0.53i) GeV. The implication of our results for the study of and the glueball is discussed.

The energy loss effect in nuclear matter ,which is another nuclear effect apart from the nuclear effect on the parton distribution as in deep inelastic scattering process ,can be measured best by the nuclear dependence of the high energy nuclear Drell-Yan process. By means of the nuclear parton distribution studied only with lepton deep inelastic scattering experimental data, measured Drell-Yan production cross sections for 800GeV proton incident on a variety of nuclear targets are analyzed within Glauber framework which takes into account energy loss of the beam proton. It is shown that the theoretical results with considering the energy loss effect are in good agreement with the FNAL E866.

No abstract