https://doi.org/10.1140/epjc/s10052-011-1600-y
Special Article - Tools for Experiment and Theory
Optimisation of variables for studying dilepton transverse momentum distributions at hadron colliders
1
Institute for Theoretical Physics, ETH Zurich, 8093, Zurich, Switzerland
2
Particle Physics Group, School of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK
* e-mail: twyatt@fnal.gov
Received:
9
September
2010
Revised:
17
February
2011
Published online:
10
March
2011
In future measurements of the dilepton (Z/γ
∗) transverse momentum, Q
T
, at both the Tevatron and LHC, the achievable bin widths and the ultimate precision of the measurements will be limited by experimental resolution rather than by the available event statistics. In a recent paper the variable a
T
, which corresponds to the component of Q
T
that is transverse to the dilepton thrust axis, has been studied in this regard. In the region, Q
T
< 30 GeV, a
T
has been shown to be less susceptible to experimental resolution and efficiency effects than the Q
T
. Extending over all Q
T
, we now demonstrate that dividing a
T
(or Q
T
) by the measured dilepton invariant mass further improves the resolution. In addition, we propose a new variable, 
, that is determined exclusively from the measured lepton directions; this is even more precisely determined experimentally than the above variables and is similarly sensitive to the Q
T
. The greater precision achievable using such variables will enable more stringent tests of QCD and tighter constraints on Monte Carlo event generator tunes.
© Springer-Verlag / Società Italiana di Fisica, 2011
