Test of A0E in Hee channel
Genova team - 30/10/01

Problem reported in September Delphi week: loss of a candidate because of missed track/shower association.

Recovery procedure: force association of any track above 4 GeV/c to any shower (not belonging to other tracks) within a given angle (ANG_ASS) from the track.

Tested on several MC samples at 206.5 GeV:

  1. Hee signal (MH=114 GeV/c2)
  2. qqbar ~200k evts (xs_kk2f4143qq_e206.5_la0_1l_e1)
  3. Bhabha ~200k evts (xs_bhwide101_e206.5_la0_1l_e1)
  4. CC 4 fermion ~143k evts (xs_wphact20ccfixed_e206.5_m80.4_la0_1l_e1)
  5. NC 4 fermion ~125k evts (xs_wphact21nc4f_e206.5_m80.4_ca0_1l_e1)
  6. NC gg like ~280k evts (xs_wphact21ncgg_e206.5_m80.4_ca0_1l_e1)
Normalized to 163 pb-1  (not exact - run quality applied to real data).

Recovery tested on signal, q qbar, CC 4f and NC 4f for ANG_ASS = 0.50, 10, 20, 30 and compared with the standard (0.0).
Results are presented in  plots .

The signal and signal-like background increase significantly for ANG_ASS until 10, then flatten. On the other hand q qbar and CC 4f have a tendency to explode after 10, so this value is used in the following analysis.

A data/MC comparison at preselection level is presented in  figure . No major problem is observed.

A numerical comparison at the different analysis steps is shown in the table (the contribution from Bhabha is 0 at preselection):
 
 
Cut
DATA
Tot. BG
q qbar
CC 4f
NC 4f
NC gg like
0
933
931.
594.
293.
41.4
2.23
1
140
164.8
58.9
84.1
21.1
0.69
2
65
66.9
17.4
33.6
15.9
0.07
3
27
25.1
6.98
7.69
10.4
-
4
11
12.0
1.37
1.30
9.36
-
5
5
9.36
0.78
0.78
7.80
-

The results (and the problems) are generally the same as in the December 2000 analysis, except an increase of the qqbar background. On the other hand this is based on 12 MC events: