1

Physics Impact of Detector Performance

Tim Barklow

SLAC

March 18, 2005

2

Outline

• General Considerations– Vertex Detector– Tracker– Calorimeter– Far forward detector

• Examples of parametric physics studies– Calorimeter Ejet

– Tracker pt

• Summary

3

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

qq

4

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

5

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

6

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

7

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

8

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

9

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

10

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)

12

1

350

500

s GeV

L fb

(MeV)hM

1jet 2

jet

E (GeV )

E

e e ZH

qqbb

13

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

15

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)

16

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

20

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

22

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)

23

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.