2018 Impact factor 4.843
Particles and Fields
Eur. Phys. J. C 29, 1-10 (2003)
DOI: 10.1140/epjc/s2003-01202

How well can we reconstruct the $t\bar{t}$ system near its threshold at future e+e- linear colliders?

K. Ikematsu1, K. Fujii2, Z. Hioki3, Y. Sumino4 and T. Takahashi5

1  Department of Physics, Hiroshima University, Higashi Hiroshima 739-8526, Japan
2  IPNS, KEK, Tsukuba 305-0801, Japan
3  Institute of Theoretical Physics, University of Tokushima, Tokushima 770-8502, Japan
4  Department of Physics, Tohoku University, Sendai 980-8578, Japan
5  Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi Hiroshima 739-8530, Japan

ikematsu@post.kek.jp
fujiik@jlcuxf.kek.jp
hioki@ias.tokushima-u.ac.jp
sumino@tuhep.phys.tohoku.ac.jp
tohrut@hiroshima-u.ac.jp

(Received: 4 March 2003 / Published online: 23 May 2003)

Abstract
We developed a new method for the full kinematical reconstruction of the $t\bar{t}$ system near its threshold at future linear e+e- colliders. In the core of the method lies likelihood fitting which is designed to improve measurement accuracies of the kinematical variables that specify the final states resulting from $t\bar{t}$ decays. The improvement is demonstrated by applying this method to a Monte Carlo $t\bar{t}$ sample generated with various experimental effects including beamstrahlung, finite acceptance and resolution of the detector system, etc. In most cases the fit takes a broad non-Gaussian distribution of a given kinematical variable to a nearly Gaussian shape, thereby justifying phenomenological analyses based on simple Gaussian smearing of the parton-level momenta. The standard deviations of the resultant distributions of various kinematical variables are given in order to facilitate such phenomenological analyses. A possible application of the kinematical fitting method and its expected impact are also discussed.



© Società Italiana di Fisica, Springer-Verlag 2003