This is a posting of Qun Fan University of Rochester
Ph.D. thesis, 1996 (A. Bodek, advisor).

We describe a measurement of the charge asymmetry as a function
of lepton rapidity in $W\rightarrow\mu\nu,e\nu$ produced
in $p\overline{p}$ collisions
at \mbox{$\sqrt{s}=1.8$~TeV}. The data sample collected by the CDF detector
during 1992-1995 consists of $\approx 110k$ events corresponding to
$\approx 111~pb^{-1}$ of integrated luminosity. This is a
five-fold increase in statistics
over the previous CDF analysis~\cite{Old_ASYM}. A new analysis
technique using silicon tracking in conjunction with shower centroid 
determination is used to extend the measurement to
higher lepton rapidity up to $|y_l|=2.4$. In addition, the 
forward muon detector yields data at $1.9<|y_l|<2.5$. 
The substantial reduction in the errors and the large increase in the
kinematic range have greatly improved
the discriminating power between various proton structure functions.
The asymmetry data 
constrain the slope of ratio of the $d$ and $u$ quark momentum distributions
in the proton over the $x$ range $0.006$ and $0.34$ at $Q^2 \approx M_W^2$.
Although the data in the central region
are reproduced by modern parton distributions, there are differences
in the high rapidity regions, which imply that further tuning of
the the slope of $d/u$ ratio versus x is required.


Posted to /cdf/pub/thesis/cdf5566_WASYM.ps
    http://www-cdf.fnal.gov/thesis/cdf5566_WASYM.ps

Posted by bodek@cdfsga.fnal.gov