Документ взят из кэша поисковой машины. Адрес оригинального документа : http://zebu.uoregon.edu/~uochep/seminars/seminars-02/presentation.ps Дата изменения: Fri Aug 16 21:49:17 2002 Дата индексирования: Tue Oct 2 12:15:28 2012 Кодировка: Поисковые слова: starspots

LCDRootApps:

Collection
of
ROOT
library
functions
by
Toshinori
Abe
and
Masako
Iwasaki

Event
generation
with
PandoraPythia

JetFinder

Implements
the
ZVTOP
algorithm
1

Selection
of
events:

H
!
b

b

Ecm
=
500
GeV

m
H
=
120
GeV

unpolarized
beams

Forced
into
two
Jets
2

Vertex
nding
with
ZVTOP
should
help
identify
B
candidates
p
t
-
corrected
mass
>
2
GeV:
B
Problem:
A
lot
of
tracks
are
not
assigned
to
any
vertex,
therefore
we
are
missing
some
data
!
Goal:
If
all
the
tracks
are
correctly
assigned
to
vertices,
the
p
t
-
corrected
mass
will
increase
->
Improve
B
tagging
!
3

JetFinder:

Doesn't
always
put
the
tracks
correctly
into
two
jets

Sometimes
a
particle
makes
tracks
in
two
dierent
jets
!
Correct
Jet
assignment
is
essential
for
vertex
assignment
Number
of
tracks
that
were
not
assigned
to
any
vertex
is
much
higher
without
JetFinder
We
need
every
fraction
of
a
GeV
!
4

­1
­0.5
0
0.5
1
­1 ­0.5 0 0.5 1
cosJet1:cosJet2
{bInSameJet
==
1}
­1
­0.5
0
0.5
1
­1 ­0.5 0 0.5 1
cosJet1:cosJet2
{vertexNumber
==
77}
­1
­0.5
0
0.5
1
­1 ­0.5 0 0.5 1
cosJet1:cosJet2
{(cosJet1
<
cosJet2)&&(jetNumber==1)}
­1
­0.5
0
0.5
1
­1 ­0.5 0 0.5 1
cosJet1:cosJet2
{(cosJet1
>
cosJet2)&&(jetNumber==2)}
5

Idea
!
Perform
rst
run
and
assign
all
tracks
with
parent
in
wrong
Jet
to
the
other
Jet
Perform
second
run
and
see
what
changes:
6

­1
­0.5
0
0.5
1
­1 ­0.5 0 0.5 1
cosJet1:cosJet2
{bInSameJet
==
1}
­1
­0.5
0
0.5
1
­1 ­0.5 0 0.5 1
cosJet1:cosJet2
{vertexNumber
==
77}
­1
­0.5
0
0.5
1
­1 ­0.5 0 0.5 1
cosJet1:cosJet2
{(cosJet1
<
cosJet2)&&(jetNumber==1)}
­1
­0.5
0
0.5
1
­1 ­0.5 0 0.5 1
cosJet1:cosJet2
{(cosJet1
>
cosJet2)&&(jetNumber==2)}

0
20
40
60
80
100
120
140
160
0
100 200 300 400 500 600
htemp
Nent
=
2000
Mean
=
3.372
RMS
=
7.673
ptMassBefore
htemp
Nent
=
2000
Mean
=
3.372
RMS
=
7.673
0
20
40
60
80
100
120
140
0
100 200 300 400 500 600 700 800
htemp
Nent
=
2000
Mean
=
3.727
RMS
=
9.531
ptMassAfter
htemp
Nent
=
2000
Mean
=
3.727
RMS
=
9.531
7

CHEATING
!
1.
Of
course
we
cannot
use
this
information
in
the
experiment
2.
Unfortunately,
the
number
of
events
with
a
p
t
-
corrected
mass
>
2.0
GeV
seems
to
go
down
!
The
second
try:
Put
all
unverticized
into
the
other
Jet:

Increased
the
p
t
-
corrected
mass
even
more
8

­1
­0.5
0
0.5
1
­1 ­0.5 0 0.5 1
cosJet1:cosJet2
{bInSameJet
==
1}
­1
­0.5
0
0.5
1
­1 ­0.5 0 0.5 1
cosJet1:cosJet2
{vertexNumber
==
77}
­1
­0.5
0
0.5
1
­1 ­0.5 0 0.5 1
cosJet1:cosJet2
{(cosJet1
<
cosJet2)&&(jetNumber==1)}
­1
­0.5
0
0.5
1
­1 ­0.5 0 0.5 1
cosJet1:cosJet2
{(cosJet1
>
cosJet2)&&(jetNumber==2)}
9

0
20
40
60
80
100
120
140
160
0
100 200 300 400 500 600
htemp
Nent
=
2000
Mean
=
3.372
RMS
=
7.673
ptMassBefore
htemp
Nent
=
2000
Mean
=
3.372
RMS
=
7.673
0
20
40
60
80
100
120
140
160
180
200
0
100 200 300 400 500 600 700 800 900
htemp
Nent
=
2000
Mean
=
4.335
RMS
=
10.9
ptMassAfter
htemp
Nent
=
2000
Mean
=
4.335
RMS
=
10.9
10

On
the
other
hand,
didn't
help
with
the
number
of
events,
ei-
ther...

Second
idea:

Gamma
rays
are
totally
left
out
in
the
vertex
detector
!

Adding
their
energy
to
the
p
t
-
corrected
mass
might
lift
a
B
candidate
over
2
GeV
limit
How
do
we
get
this
information
?

Use
the
calorimeter
!
How
good
does
it
have
to
be
?
(We
need
at
least
all
gammas
from
a
B)
11

­1
­0.5
0
0.5
1
0
10000 20000 30000 40000 50000 60000 70000 80000 90000
htemp
Nent
=
121742
Mean
=
0.9617
RMS
=
0.1443
cosTheta
htemp
Nent
=
121742
Mean
=
0.9617
RMS
=
0.1443
12

TO
DO
List:

Improve
JetFinder
with
information
from
the
rst
run
of
the
Vertex
Finder
->Find
a
sensible
combination
of
(measurable)
properties
to
in-
crease
number
of
vertices
with
a
p
t
-
corrected
mass
>
2.0
GeV

Improve
Vertex
nding
even
more

Incorporate
information
about
the
gamma
rays
from
the
calorime-
ter
into
the
p
t
-
corrected
mass
13