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The European Physical Journal C
ISSN: 1434-6044 (printed version)
ISSN: 1434-6052 (electronic version)
Abstract Volume 2 Issue 2 (1998) pp 287-300
theoretical physics:
Consistent treatment of charm evolution in deep inelastic scattering
A.D. Martin (1), R.G. Roberts (2), M.G. Ryskin (1)(3), W.J. Stirling (1)(4)
(1) Department of Physics, University of Durham, Durham, DH1 3LE, UK
(2) Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX, UK
(3) Laboratory of Theoretical Nuclear Physics, St. Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg 188350, Russia
(4) Department of Mathematical Sciences, University of Durham, Durham, DH1 3LE, UK
Received: 12 May 1997 / Revised version: 12 June 1997
Abstract. We present a formulation which allows heavy quark $(c, b, \ldots)$ mass effects to be explicitly incorporated in both the coefficient functions and the splitting functions in the parton evolution equations. We obtain a consistent procedure for evolution through the threshold regions for $c\overline c$ and $b\overline{b}$ production in deep inelastic scattering, which allows the prediction of the charm and bottom quark densities. We use the new formulation to perform a next-to-leading order global parton analysis of deep inelastic and related hard scattering data. We find that the optimum fit has $\alpha_S(M_Z^2) = 0.118$. We give predictions for the charm components of the proton structure functions $F_2$ and $F_L$ as functions of $x$ and $Q^2$ and, in particular, find that $F_2^c$ is in good agreement with the existing measurements. We examine the $Q^2$ range of validity of the photon-gluon fusion model for $c\overline c$ electroproduction. We emphasize the value of a precision measurement of the charm component $F_2^c$ at HERA.
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Online publication: April 8, 1998
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