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Parton energy loss limits and shadowing in Drell-Yan dimuon production

M. A. Vasiliev, M. E. Beddo, C. N. Brown, T. A. Carey, T. H. Chang, W. E. Cooper, C. A. Gagliardi, G. T. Garvey, D. F. Geesaman, E. A. Hawker, X. C. He, L. D. Isenhower, D. M. Kaplan, S. B. Kaufman, D. D. Koetke, W. M. Lee, M. J. Leitch, P. L. McGaughey, J. M. Moss, B. A. Mueller, V. Papavassiliou, J. C. Peng, G. Petitt, P. E. Reimer, M. E. Sadler, W. E. Sondheim, P. W. Stankus, R. S. Towell, R. E. Tribble, J. C. Webb, J. L. Willis, G. R. Young

Abstract

A precise measurement of the ratios of the Drell-Yan cross section per nucleon for an 800 GeV/c proton beam incident on Be, Fe and W targets is reported. The behavior of the Drell-Yan ratios at small target parton momentum fraction is well described by an existing fit to the shadowing observed in deep-inelastic scattering. The cross section ratios as a function of the incident parton momentum fraction set tight limits on the energy loss of quarks passing through a cold nucleus.

Parton energy loss limits and shadowing in Drell-Yan dimuon production

Abstract

A precise measurement of the ratios of the Drell-Yan cross section per nucleon for an 800 GeV/c proton beam incident on Be, Fe and W targets is reported. The behavior of the Drell-Yan ratios at small target parton momentum fraction is well described by an existing fit to the shadowing observed in deep-inelastic scattering. The cross section ratios as a function of the incident parton momentum fraction set tight limits on the energy loss of quarks passing through a cold nucleus.

Paper Structure

This paper contains 3 equations, 3 figures, 1 table.

Figures (3)

  • Figure 1: Ratios of the measured cross section per nucleon for Drell-Yan events versus dimuon mass (in GeV/$c^2$), $x_2$, $x_F$ and $x_1$. The upper (lower) panels show ratios of Fe/Be (W/Be) from the present experiment as solid circles and Fe/C (W/C) from E772 as open circles. The errors are statistical only. The solid curves are the predicted cross section ratios, integrated over the hidden variables, from leading-order calculations using EKS98 esk and MRST MRST.
  • Figure 2: Ratios of the measured Drell-Yan cross section per nucleon versus $p_T$. Ratios of Fe/Be and W/Be from the present experiment are shown as solid circles, and ratios of Fe/C and W/C from E772 are shown as open circles. The solid curves are shadowing predictions for the present experiment from leading-order calculations using EKS98 esk and MRST MRST.
  • Figure 3: Ratios of the cross section per nucleon versus $x_1$ for Fe/Be (upper panel) and W/Be (lower panel), corrected for shadowing. The solid curves are the best fit using the energy loss form (\ref{['eq:1']}), and the dashed curves show the $1\sigma$ upper limits. The dotted curves show the $1\sigma$ upper limits using the energy loss form (\ref{['eq:3']}). The $1\sigma$ upper limit curves using the energy loss form (\ref{['eq:2']}) are essentially identical to those using form (\ref{['eq:3']}).