Artikel über N.Tesla

III-62
3 Supersymmetry
a
b
Figure 3.2.2: Energy spectra E µ of muons from the reactions a) e − L e+ R → ˜µ L˜µ L →
µ − ˜χ 0 2 µ+ ˜χ 0 2 and b) e− L e+ R → ˜ν µ¯˜ν µ → µ − ˜χ + 1 µ+ ˜χ − 1 at √ s = 500 GeV for L = 250fb −1 .
˜l, ˜ν m [GeV] δm c [GeV] δm s [GeV]
˜µ R 132.0 0.3 0.09
˜µ L 176.0 0.3 0.4
˜ν µ 160.6 0.2 0.8
ẽ R 132.0 0.2 0.05
ẽ L 176.0 0.2 0.18
˜ν e 160.6 0.1 0.07
˜τ 1 131.0 0.6
˜τ 2 177.0 0.6
˜ν τ 160.6 0.6
˜χ m [GeV] δm c [GeV] δm s [GeV]
˜χ ± 1 127.7 0.2 0.04
˜χ ± 2 345.8 0.25
˜χ 0 1 71.9 0.1 0.05
˜χ 0 2 130.3 0.3 0.07
˜χ 0 3 319.8 0.30
˜χ 0 4 348.2 0.52
Table 3.2.1: Expected precision on masses, scenario RR1, using polarised e ± beams
(P − = 0.8, P + = 0.6). δm c from decay kinematics measured in the continuum (L =
160(250)fb −1 at √ s = 320(500) GeV) and δm s from threshold scans (L = 100fb −1 ).
Measurements of ˜τ and ˜ν τ of the third slepton generation are less favourable. While
identification via decays τ ˜χ will be easy and efficient, the background is large (W + W −
production) and a mass determination via energy spectra is much less accurate, of the
order of a few per cent [9]. But from cross section measurements at threshold one may
obtain mass resolutions around half a per cent. The expected accuracies on slepton
masses for mSUGRA model RR1 are given in Table 3.2.1.
3.2.2 Slepton properties
A very important topic is the determination of the quantum numbers. Sleptons carry
spin 0, but otherwise the SM quantum numbers of leptons. The differential cross section
for s-channel exchange is proportional to β 3 sin 2 ϑ. A consistency check, although not
unique, can be obtained from the β dependence of the cross section scan at threshold.