Signatures IV Group Report

ALCPG07 FNAL, Oct 26 2007Bruce Schumm, UCSC/SCIPP

Momentum Reconstruction, V0 Finding, and Charged Particle ID

Apologies to 4th Concept (I’m not yet familiar enough to be confident in criticism…)

Our charge was broad – to find signatures that would inform detector design regarding:

• Momentum resolution• Forward tracking (pattern rec. + resolution)• Non-prompt tracks (was stated as “V0s”)• Dedicated charged particle ID

Our discussion centered around the usual candidates: SUSY, SM Higgs, WW but with some new or re-calibrated emphases…

KS0 Efficiency and Energy Flow

Form jet/jet mass for e+e- qq at Ecm = 500 GeV

Remove 10% of KS0 and form RMS deviation

from perfect reconstructionFind 97% = 2.5 GeV, or 0.5% degradation

Chris Meyer, UCSC

SUSY in Perspective (Tom Rizzo) “Can the ILC at 500 GeV distinguish all of the MSSM models (i.e., parameter space points) that were found to give degenerate signatures at the LHC ?? Can the SUSY particles in all these models be observed at ILC?”

“Along the way to answering these questions we needed to perform a general study of signals & backgrounds for hundreds of SUSY models providing a unique opportunity to examine, e.g., signatures, cuts, detector and simulation properties & our basic assumptions/prejudices about SUSY analyses at the ILC.”

These “hundreds of models” include some interesting signatures, some of which challenge one or both of the detector concepts…

Anomaly-Mediated Supersymmetry Breaking

Chargino () tends to be nearly degenerate with neutralino (0) phase-space suppression

For M < m, model yields effectively stable massive charged particles

How long it () lives…

and how it dies.

Anomaly-Mediated Supersymmetry Breaking with M < m (Stable Charged SUSY Partner)

Rizzo et al. have developed a workable selection for Ecm = 500 GeV

The velocity criterion =p/E < 0.93 is interesting…

Faster (lighter) ruled out by direct searches (LEP)

= 0.93

But: LHC will probably see or rule out lighter end of spectrum ILC velocity measurement in 1/2 regime

Probably not a motivation for dedicated PID

Region ofinterest

Long-Lived Heavy Charged Particle

Anomaly-Mediated SUSY with M m Soft Isolated Tracks

Typical signature: two unac-companied charged tracks with p

~ 200 MeV

well motivated, and quite challenging; good to consider?

But: could this be done even with perfect tracking?

Two-photon backgrounds will be challenging (deflected beam elec-trons have angle ~ p

/Ebeam ~ 10-4)

G̃

l̃

l

Gauge-Mediated Supersymmetry Breaking

Scenarios with in-flight decay not disfavored by cosmological constraints

For a reasonable range of, e.g., gravitino mass, signature would be kinked track (possible with change in rate of

ionization loss

kink

Gauge-Mediated Supersymmetry Breaking II

Well-motivated, trac-table signal.

This will challenge SiD, and make group think about layout and z segmentation.

What about gaseous tracking? (For TPC, non-pointing out-of-time)

kinkMinimum for prompt track trconstruction

Minimum for non-prompt track trconstruction

kink

Selectrons vs. cos()

-0.9 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.91,000

2,0003,0004,0005,0006,000

7,0008,0009,00010,00011,000

12,00013,00014,00015,00016,000

SUSY: Particle cos(theta) (no cuts)

Electrons vs. cos()

cos()

Electrons

Opening of t-channel pitches

majority of signal forward. But also…

Light Selectrons

Spectrum is weighted towards higher energy at

high |cos()|, increasing stats/ at

critical upper endpoint

Energy Distribution

0

50

100

150

200

250

300

350

400

450

0 7 14 22 29 36 43 50 58 65 72 79 86 94 101

108

115

122

130

137

144

151

158

166

173

180

187

194

202

209

216

223

230

238

245

252

259

266

274

281

288

Energy GeV

Coun

ts

Electron Energy Specturn

0 ~150

For light SPS1a-like scenario, majority of slepton mass information would be in forward direction

This would challenge any solenoidal-geometry design

Other Interesting Forward Physics:Triple Gauge Boson Couplings

Observation of anomalous couplings would suggest an effective internal structure to gauge bosons, and cause

us to re-think the nature of the electroweak scale

Single W“Double W” Production

Triple Gauge Boson Couplings II

[d/

dcos

W]/S

M

ALR

Greatest sensitivity is in far-backward direction (cos ~ -1) where t-channel is suppressed

Triple Gauge Boson Couplings III

0.9

0.99

Nominally, tracking (and calorimetry) has coverage, but need full simulation to confirm

expectations (backgrounds, boosts)

Precision Momentum Measurement: H (H. Yang, K. Riles, U. Michigan)

Xe+e- HZ

+-Higgs BFs(vs MH)

Since light Higgsis narrow, spec-ulate that M resolution islimited by tracker resolution…

H Significance vs. Tracker resolution

Rescaling factor rel-ative to SiDMar01:(1/p) = a b/p

a = 2 x 10-5

b = 7 x 10-4

Sensitivity improves well beyond 2 x 10-5

Best shot at 2nd gen. fermion? (H. Logan)

What About Dedicated Charged Particle ID?Can be useful in flavor & charge separation• H bb vs. H cc• Forward-backward asymmetries in

e+e- Z ff,K indicative of heavy flavor cascade, and tag chargeProbably best to study via vertex recon-struction Neural Net; no group has yet taken this on.

Are we missing some compelling motivation?

Summary (I of III)

Artwork courtesy J. Pollock

There are some well-motivated signatures that will challenge one or both detectorsIt’s not clear that experimentalists or theorists have thought them through adequately.

SUSY• AMSB leads to events with a few soft tracks – must understand backgrounds before designing tracking for this signature• GMSB leads to tractable signal with kinked tracks

Summary (II of III)Forward Tracking• Light sleptons present opportunity/challenge for momentum resolution of forward tracker• WW production might be good place to confirm reconstruction capabilities

Momentum Resolution• H presents new challenge to momentum resolution in central detector

Dedicated Charged Particle ID• Tagging contribution unexplored. Are we missing anything?

Summary (III of III)

Artwork courtesy J. Pollock

The “signatures” format worked well for our group; time was too short. Ideally, we should keep in touch. For example…It would be quite possible to improve the p momentum resolution by x5. But would the cost ($$$, compromising other physics) be worth it?It’s not enough for theorists to propose and experimentalists to study: some dialog is needed for optimization.“Signatures” was a good start. What next?

RANDOM (THOROUGHLY)

BACKUP SLIDEES

Battaglia et al. Benchmarks (2006)

selectrons

LSP

SPS 1 Spectroscopy:At Ecm = 1Tev, selectrons and neutralino are

light.

Beam/Brehm:√smin=1 √smax=1000 = .29sz = .11 (mm)

Error for COSTHETA Ranges

0.0380.046

0.086

0.073 0.078

0.194

0.0800.090

0.0970.106

0.111

0.200

0.000

0.050

0.100

0.150

0.200

0.250

-0.01% 0.19% 0.39% 0.59% 0.79% 0.99% 1.19%Beamspread

Erro

r

PERFECT 0-1

PERFECT 0-.8

SDMAR01 0-1

SDMAR01 0-.8

Now, include the full region (|cos| < 0.994)

G̃

l̃l

Gauge-Mediated Supersymmetry Breaking

Scenarios with in-flightdecay are motivated by

cosmological constraints

This will challenge SiD. What about gaseous trackers? (For TPC, non-pointing out-of-time)

kink

Minimum for prompt track trconstruction

Minimum for non-prompt track trconstruction

SCHUMM’S GUIDE to squeezing blood from stone

1. Discriminate

2. Nurture

3. Produce