Physics Impact of Detector Performance
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Physics Impact of Detector Performance
Tim Barklow
SLAC
March 18, 2005
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Outline
• General Considerations– Vertex Detector– Tracker– Calorimeter– Far forward detector
• Examples of parametric physics studies– Calorimeter Ejet
– Tracker pt
• Summary
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Vertex Detector
• Classic application of b,c tagging to Higgs branching ratios.
• But there’s more:– vertex charge
• top, W helicity
• asymmetries
tagging• stau analyses
• Higgs tau BR
• b jets with several ’s
HM (GeV)
bb
ggcc
W W
*Talk by Chris Damerell 21Mar2005
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Vertex Detector – tau tagging example
t
is an important strong symmetry
breaking signal (WW ).
The large background can be
mostly supressed by vetoing the forward e
and requiring unbalanced p . But there remains
a seem
e e tt
tt
e e e e tt
ingly irreducible background from
where one
of the quarks undergoes the decay
decays have at least 2 , , etc.
Tau tagging could reduce th
's
is b
e b
e e e e tt e e bbW W
b
b c c ce
ackground
(and help jet energy flow analysis in general).b
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Tracker
• Momentum resolution set by recoil mass analysis of
• reconstruction and long-lived new particles (GMSB SUSY)
• Multiple scattering effects• Forward tracking• Measurement of Ecm,
differential luminosity and polarization using physics events
ZH l l X 0 0 , SK
52
2 10t
t
p
p
Recoil Mass (GeV)
52
8 10t
t
p
p
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Calorimeter
• Separate hadronically decaying W’s from Z’s in reactions where kinematic fits won’t work:
• Help solve combinatoric problem in reactions with 4 or more jets
E/E = 0.6/E
E/E = 0.3/E*e e ZH qqWW qqqql
e e ZHH qqbbbb
0 01 1 1 1
0 0 0 02 2 1 1
, e e W W ZZ
e e W W
e e ZZ
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Far Forward Detector
• Electron veto down to 3.2 mrad in presence of very large pair background
• Useful in general to suppress backround. Takes on added importance given that the SUSY parameter space consistent with Dark Matter density includes region with nearly degenerate
• Crossing angle implications.
ff
01 ,
e e
signal
after 3.2 mrad vetoe
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M/M
stau
(%
)
Far Forward Detector
0cross 20 mradcross
Rel. stau mass error increases from 0.14% to 0.22% with 20 mrad cross angle
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C. Castanier et al. hep-ex/0101028
Signal significance at = 500 GeV
for
s
e e ZHH qqbbbb
1
J.-C. Brient, LC-PHSM-2004-001
Error on ( *) from
measurement of
*
at 360 GeV, L=500 fb
BR H WW
e e ZH qqWW qqqql
s
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jet
jet
E0.3
E
jet
jet
E0.3
E
Reconstructed Mbb 4C Fitted Mbb
0.4
0.5 0.6
0.4
0.5 0.6
e e ZH qqbb
Mbb (GeV) Mbb (GeV) Mbb (GeV) Mbb (GeV)
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1
350
500
s GeV
L fb
jet
jet
42 MeV
E0.3
E
hM
e e ZH
qqbb
jet
jet
46 MeV
E0.4
E
hM
jet
jet
48 MeV
E0.5
E
hM
jet
jet
50 MeV
E0.6
E
hM
Mbb (GeV) Mbb (GeV)
Mbb (GeV) Mbb (GeV)
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1
350
500
s GeV
L fb
(MeV)hM
1jet 2
jet
E (GeV )
E
e e ZH
qqbb
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2 sint
t t
p ba
p p
Simdet Fast MC with this parameterization of pt resolution in place of Simdet’s emulation of LDC:
5
3
2.1 10
1.0 10
a
b
2
t
t
p
p
10log (1 cos ) 10log (1 cos )
SiD Detector Resolution
p=20 GeV, SIMDET LDC
p=20 GeV
p=3 GeV
p=100 GeV
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2 sint
t t
p ba
p p
5
3
2.0 10
1.0 10
103 MeVh
a
b
M
5
3
1.0 10
1.0 10
85 MeVh
a
b
M
5
3
4.0 10
1.0 10
153 MeVh
a
b
M
5
3
8.0 10
1.0 10
273 MeVh
a
b
M
1
350
500
s GeV
L fb
Recoil Mass (GeV)
Recoil Mass (GeV)
Recoil Mass (GeV)
Recoil Mass (GeV)
e e ZH
X
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2 sint
t t
p ba
p p
5
3
2.0 10
1.0 10
103 MeVh
a
b
M
5
3
2.0 10
0.5 10
96 MeVh
a
b
M
5
3
2.0 10
2.0 10
124 MeVh
a
b
M
5
3
2.0 10
4.0 10
188 MeVh
a
b
M
1
350
500
s GeV
L fb
e e ZH
X
Recoil Mass (GeV) Recoil Mass (GeV)
Recoil Mass (GeV) Recoil Mass (GeV)
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5 3 10 or 10a b
e e ZH
X
(MeV)hM
1
350
500
s GeV
L fb
vs hM a
vs hM b
2 sint
t t
p ba
p p
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Muon Energy (GeV)
R Re e 1500 500s GeV L fb 224 GeVR
M
5 5 3 3
No dependence on or in the range
1.0 10 8.0 10 , 0.5 10 4.0 10
a b
a b
Muon Energy (GeV) Muon Energy (GeV) Muon Energy (GeV)
2 sint
t t
p ba
p p
52 10a 51 10a
54 10a 58 10a
31 10b 30.5 10b
32 10b 34 10b
34M MeV
Fit for onlyM
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Branching Ratio of H CC
Br/Br ~ 39% (120GeV), 64% (140GeV) for Zl+l-, 1000 fb-1
e e ZH
l l X
* Talk by Haijun Yangin TRK session 20Mar2005
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Ebeam (GeV)
beam (incoming) E 250 GeVBeam Energy Profiles
Before Collision After Collision Lumi Weighted
Ebeam (GeV) Ebeam (GeV)
Ecm 0.1% B 4.3% B 1.6%
Center of Mass Energy Error Requirements
• Top mass: 200 ppm (35 Mev)• Higgs mass: 200 ppm (60 MeV for 120 GeV Higgs) • Giga-Z program: 50 ppm
biasCM50 ppm < E < 250 ppm
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cm
+
Reconstructed E using Z events and
measured angles. Z
Ecm (GeV)
1
350
100
s GeV
L fb
Ecm = 47 MeV
* Talk by Klaus Moenigin MDI session 20Mar2005
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In the reaction we know the mass
of the photon. Why not invert the problem and use
the excellent moment
The momentum resolution is set by Higgs recoil mass
measur
um
ement in e e ZH H
e e Z
resolution to solve
for instead of the mass of the system opposite ?s
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c
cm
m
E = 2 Ge
E
V
= 2 GeV
cm Z
+
Reconstructed E & M using Z events and
measured momenta & angles. Z
Ecm (GeV)
M (GeV)
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T
T
r
rk
k
mom
mom
scale f
scale fa
actor
ctor =
=
0
1
.996
.004
cm Z
+
Reconstructed E & M using Z events and
measured momenta & angles. Z
Ecm (GeV)
M (GeV)
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Z
cm
1cm
cmE = Measured E assuming Z boson recoil against single
E 350 G
E = Measu
eV
red E
Lumi 100
using full energy
photon
f
b
e e
cmcm cm cm
cm
Z
5 3Z
5 3Z
Z
Emeasured var E (GeV) E (GeV) E (GeV) (ppm)
E
stat sys(E scale) total total
E ang only .0473 0 .0473 135
E |p| & ang 2 10 1 10 .0085 .0206 .0223 64
E |p| & ang 2 10 .5 10 .0054 .0124 .0135 39
E |p
a b
5 3
5 3
| & ang 34 10 4 10 .0375 .0313 .0488 139
E |p| & ang 2 10 1 10 .0056 .0124 .0136 39
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angles only
5 3 10 or 10a b
EZ vs b
EZ vs a
E vs a
E vs b
E SIMDET LDC
EZ SIMDET LDC
2 sint
t t
p ba
p p
Ecm Resolutionin MeV vs a or b
e e
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angles only
5 3 10 or 10a b
EZ vs b
EZ vs a
E vs aE vs b
E SIMDET LDC
EZ SIMDET LDC
2 sint
t t
p ba
p p
e e
Ecm Resolutionin MeV vs a or b
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2 sint
t t
p ba
p p
Simdet Fast MC with this parameterization of pt resolution in place of Simdet’s emulation of LDC:
5
3
2.1 10
1.0 10
a
b
2
t
t
p
p
10log (1 cos ) 10log (1 cos )
SiD Detector Resolution
p=20 GeV, SIMDET LDC
p=20 GeV
p=3 GeV
p=100 GeV
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Summary
• Current detector designs appear well matched to envisioned physics program
• Choices will have to be made as realitities of detector engineering and cost are confronted – physics benchmark studies will play a crucial role. The examples of parametric studies shown here are just the beginning.