Measuring gauge-mediated supersymmetry breaking parameters at a 500 GeV e(+)e(-) linear collider

S. Ambrosanio et Ga. Blair, Measuring gauge-mediated supersymmetry breaking parameters at a 500 GeV e(+)e(-) linear collider, EUR PHY J C, 12(2), 2000, pp. 287-321
Citations number
Categorie Soggetti
Journal title
ISSN journal
1434-6044 → ACNP
Year of publication
287 - 321
SICI code
We consider the phenomenology of a class of gauge mediated supersymmetry (S USY) breaking (GMSB) models at a e(+)e(-) Linear Collider (LC) with E-c.o.m . up to 500 GeV. In particular, we refer to a high-luminosity (L similar to 3 x 10(34) cm(-2) s(-1)) machine, and use detailed simulation tools for a proposed detector. Among the GMSB-model building options, we define a simpl e framework and outline its predictions at the LC, under the assumption tha t no SUSY signal is detected at LEP or Tevatron. We assess the potential of the LC to distinguish between the various SUSY model options and to measur e the underlying parameters with high precision, including for those scenar ios where a clear SUSY signal would have already been detected at the LHC b efore starting the LC operations. Our focus is on the case where a neutrali no ((N) over tilde(1)) is the next-to-lightest SUSY particle (NLSP), for wh ich we determine the relevant regions of the GMSB parameter space. Many obs ervables are calculated and discussed, including production cross sections, NLSP decay widths, branching ratios and distributions, for dominant and ra re channels. We sketch how to extract the messenger and electroweak scale m odel parameters from a spectrum measured via, e.g. threshold-scanning techn iques. Several experimental methods to measure the NLSP mass and lifetime a re proposed and simulated in detail. We show that these methods can cover m ost of the lifetime range allowed by perturbativity requirements and sugges ted by cosmology in GMSB models. Also, they are relevant for any general lo w-energy SUSY breaking scenario. Values of c tau((N) over tilde 1) as short as 10's of mu m and as long as 10's of m can be measured with errors at th e level of 10% or Letter after one year of LC running with high luminosity. We discuss how to determine a narrow range ( less than or similar to 5%) f or the fundamental SUSY breaking scale root F based on the measured m((N) o ver tilde 1), c tau((N) over tilde 1). Finally, we suggest how to optimise the LC detector performance for this purpose.