From:	SMTP%"Hans.Grassmann@trieste.infn.it" 27-OCT-1997 11:04:49.72
To:	TOBACK
CC:	
Subj:	susy draft

Date: Mon, 27 Oct 1997 18:01:09 +0100 (CET)
To:   toback@uccdf.uchicago.edu, frisch@uccdf.uchicago.edu,
             reb@hep.anl.gov, stk@sgi6.hep.anl.gov, yagil@fnald.fnal.gov,
             mdshapiro@lbl.gov
CC:   GRASSMANN@trieste.infn.it
Message-Id: <971027180109.2e6664e5@trieste.infn.it>
From: <Hans.Grassmann@trieste.infn.it>
Subject: susy draft


concerning cdf 4149

dear authors, dear godparents
in your draft you quote the probability of the event to be
caused by the effect of double interactions as 8*10-9.
This number ignores the fact, that we have observed
in this event a second interaction of about the
same q**2 as the primary interaction. Something like this
to happen is extremly unlikely, as your number illustrates,
but we actually have observed that it did happen. it is a fact.

the relevant probability to quote would be "what is the probability
for such an event to occur in a sample of events where the
second interaction is of very high q**2"

I believe that the draft in its current version is misleading, as
it claims that we have observed an event which we cannot explain,
but this is not necessarily true.
please tell me, if I have understood something wrongly.

best regards
hans

** I'm afraid you have understood something wrongly. There is no second high-q^2
   vertex in this event. To paraphrase from CDF Note 4304, P6. There are a total
   of 4 class 12 vertices (2 class 1 vertices)

   The vertices have  Pt=40.6 (The primary), 1.2, 5.0  and 5.4 respectively. The
   last two  share 2.0  GeV of  tracks so they  are not   independent. The other
   vertices, which are class 11 have z= 96.4 and z=89.5, both with Pt<1 GeV.

   The method used to  estimate the probability of a  second interaction causing
   this type of signature  are integrated over all  Pt of any other vertices. In
   addition,  we have  multiplied by a  factor of  6 (all  permutations of the 4
   class 12 vertices in the  event) to estimate the  rate. This is done in great
   detail in CDF Note 3892,  in particular see page  16 and 17. While this could
   be the source of  the event (and we  will never know) we  only expect that we
   should  see 8E-9  events  with this   signature from  two  overlapping events
   occurring during the same bunch crossing.