De Roeck

1
e-e-, gamma-gamma and e-gamma options for a
Linear Collider

• De Roeck
• CERN

Amsterdam, April 2003
2
In this study

• Gamma-gamma and e-gamma option
• Working group on gamma-gamma/e-gamma collider
  technology
• K. Moenig and V. Telnov
• Working group on gamma-gamma physics
• M. Kraemer, M. Krawczyk, S. Maxfield,
  ADR, (S. Soldner-
• Rembold)
• 42 meetings during this study
• During ECFA/DESY, integrated with other physics
  groups/ worked well!
• Many new results
• e-e- option
• No new studies in the context of this workshop/ 2
  meetings St Malo/Amsterdam C. Heusch
• Will remind some key issues based on
  Snowmass/Jeju reports

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e-e-option
Advantages of e-e- Large polarization for both
beams eL,eR Exotic quantum numbers (H--)
Larger sensitivity in some processes Some very
clean processes No s-channel, lower luminosity
Sensitivity to contact interactions
Non-Commutative QED
Majorana neutrinos
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e-e- option
Higgs production
Supersymmetry
CP viol. phases
But No detector simulation, IR, beamstrahlung,
selectron width
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e-e- option
Parameters (Snowmass 2001) Study for TESLA (S.
Schreiber)
Luminosity 5-(10)1033 cm-2 s-1 L e-e- 1/6
(1/3) L ee- Stability OK with intra-train
feedback system
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e-e- option
S. Schreiber
No major changes required in IP or accelerator
e-e- is the option which will be most easily to
realize (for TESLA) Has to be kept on the roadmap
Future control room at the FLC??
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Gamma-gamma and e-gamma

• Compton backscattering on laser photons
• ? Needs second interaction point
• ? Needs crossing angle
• ? Peaked but smeared spectrum
• Hence needs extra effort
• Is it worthwile?
• Jeju panel discusion ? Yes!
• Examples of advantages
• Higher cross sections for charg. particles
• Different JPC state than in ee-
• Higgs s-channel produced
• Higher mass reach in some scenarios
• ? CP analysis opportunities
• ? Can test precisely couplings to photons

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Gamma-gamma and e-gamma

• TESLA-TDR/ PLC workshop Hamburg 2000
• Golden processes identified? Starting
  point in Krakow
• Only light Higgs?bb and QCD processes
  simulated (simplified)
• This study Level of detail in ?? as good as in
  ee-
• SIMDET simulation for more golden processes
• H ? WW, ZZ , Heavy MSSM H A, WW production,
  Susy
• Cross checks/elaborate for key process Higgs ?bb
• Further opportunities CP studies, Extra
  Dimensions, NC QED,..
• Real luminosity spectra/polarization used
  (CIRCE, CompAZ)
• B search using ZVTOP
• Adding overlap events
• QCD backgrounds in NLO
• QCD Monte Carlo tuning to existing data
• Direct contact exchange with the US
  studies/exchange tools

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Gamma-gamma and e-gamma

• Backgrounds and Luminosity
• Luminosity/polarisation measurement (
  corresponding syst.)
• Background studies (pairs, photons, neutrons)
• Evaluate design of IP/Mask/vertex detectors
• Technology
• RD efforts in Europe and the US

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Golden Processes
hep-ph/0103090

• ?? ? ?
• ?
• ? ? ? ?
• ?
• ? ? ? ?
• NO
• W

• ?
• ? ? ? ?
• TDR

Higgs
SUSY
Tril/quart.
Top
QCD

• Being done or ready should be ready for the
  writeup
• promised

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Golden Processes
Added at/since the Krakow meeting ?
Non-commutative QED ? e? for EDs Light
gravitinos Radions Gluino production
? H??? (US groups) ? H?HH- (US groups)
CP analyses in the Higgs sector More (as yet
uncovered/lower priority at present) e??e
Leptoquarks Strong WW scattering e??eH

As always still room for volunteers (next
workshop)
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Gamma-gamma and e-gamma
On our group web page
Information on lumi spectra, special SIMDET
version, background
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Luminosity Spectra
TDR parameters
Luminosities files with PHOCOL (V. Telnov) Can
be used via CIRCE (T. Ohl) Analytical
approximation COMPAZ (A. Zarnecki)
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Luminosity Measurement
Moenig,Marfin,Telnov

• Proposals
• ee ? ee (??) / not for J0
• ee ? ee? (???)
• ee ? 4 leptons
• Precision 0.1 (stat)
• For Higgs (J0) e.g. ee ? ee?

• For e? collisions
• e? ? e?
• e? ? eee

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Monte Carlos Tuning
SHERPA Generator (F. Kraus et al.) Tuning of
the Monte Carlo models via JETWEB (M. Wing)

• Amegic Wing

Resolved Direct
A tune for LC ?? studies has been produced
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Background studies
backgrounds studied for TESLA IP layout
Study beam related background ? of QCD events
overlapping now under control ( 1 evt_at_ 200
GeV and 2.5 evts _at_500 GeV). All groups agree
(D. Asner, ADR, Telnov, Warsaw) ? of hits
in the layers of the pixel detector per bunch
crossing ? Incoherent pair production
essentially the same as for ee- ? Coherent
pair production High! but ok, similar to
ee- ? same vertex detector as for ee-

(Moenig,Sekaric) ? Neutrons? Probably
ok (V. Telnov)
Moenig et al
1st layer
2nd layer
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Background studies
New two-mask design
Moenig,Sekaric
Improves background by factor 2-3
Still being optimized Backg ?/bx
incoh/coh From outer mask 2.103/104 Tracks in
TPC 103/2.103 Hits in vtx
368/20 Similar as in ee- IP with present
mask design
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QCD
QCD had been mostly studied --at detector
level-- for the TDR Not revisited this
time

• Exceptions (using new data)
• Total ?? cross section parametrizations
• (Kwiecinski, Motyka,Timneanu) (Pancheri,
  Grau, Godbole, ADR)
• Structure functions PDFs
• (Krawczyk et al.)

To be used in the Monte Carlo programs
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Higgs
Heralded as THE key measurement for the
gamma-gamma option

• From the TDR (Jikia, Soldner-Rembold)
• This workshop
• Study H? bb, with realistic spectra, background,
  B-tagging efficiency,
• Study H? WW,ZZ
• Study model separation power
• Study spin of Higgs in H? WW,ZZ
• Study CP properties of the Higgs
• Study MSSM Higgs (H,A) extend ee- reach
• Study of the Charged Higgs (US)

10 3
250 350
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SM Higgs analyses
P. Niezurawski
1 year/84 fb-1
Corrected inv. mass
Using NLO backgrounds (Jikia) Next
question Systematics??
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SM Higgs Analysis
A. Rosca

• Analysis of a second group (Zeuthen)
• Taking into account the QCD radiative corrections
  to the background process (Pythia
  NLO Xsec.) through a reweighting procedure.
• Adopting a b-quark tagging algorithm based on a
  neural network.

1.9
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SM Higgs H?WW,ZZ
A. Zarnecki
Simultaneous determination of the Higgs Boson
width and phase H? WW and H? ZZ
measurements (full detector simulation)
????/??? 3-10 MHlt 350 GeV
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SM Higgs Analysis
Warsaw group
2HDM SM-like versus SM (Ginzburg et al.)
Different masses
MH?bb (GeV) ??/?
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MSSM H/A Higgs
One year running and ?s ? 500
GeV A0 detectable for MA gt 300 GeV
beyond the ee- reach
Extend the detailed analysis to H/A? bb
P. Niezurawski
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MSSM H/A Higgs
Study for a ee- collider at 630 GeV
ee-
??

• D.Asner/J.Gunion (LCWS02)
• ? Extends ee- reach
• Need few years to close
• the LHC wedge
• European study in progress

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Angular distributions in ???h?ZZ?lljj and
???h?WW?4j
? Higgs spin and parity
A. Zarnecki
D. Miller et al. hep-ph/0210077
Detector effects are large, but sensitivity left
??
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CP studies via ?????tt
R. Godbole et al. hep-ph/021136
LCWS02 Exciting possibility to analyse CP
structure of the scalar Construct
combined asymmetries from intial lepton
polarization and decay lepton charge Done with
Compton spectra Using COMPAZ reduces sensitivity
with factor 2 Needs detector simulation
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Triple Gauge Couplings
Study ???WW e??W?
Sekaric, Moenig Bosovic, Anipko
Includes detector simulation/3D fits
sensitivity proportional to the momentum of
the particles involved in the triple gauge boson
vertex
Studies starting for quartic couplings in ???WW
and ???WWZ I Marfin Use of optimal variables
F. Nagel et al.
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TGC analysis with optimal obs.
New developments
Nagel,Nachtmann, Pospischil
Fixed photon beam energy/ No detector simulation
Comparison with ee-?
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Extra Dimensions
ADD type extra dimensions Sensitivity to mass Ms
P. Poulose
???tt
Realism reduces sensitivity Ms1.7 TeV to 1.4 TeV
?see 500 GeV
?-1
SM2? SM-2?
?1
Ms
Ms
Ideal Compton spectrum
COMPAZ spectrum
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Supersymmetry
Theoretical studies ???gluinos Interesting but
needs simulation
Several analyses starting ???charginos
???squarks e??slepton neutralino Will be
pursued up to the detector level E.g.
Kraus, Wengler
Klasen, Berge
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Technology

• Photon collider IP introduces new challenges
• Laser
• Optics
• Stability control in the IP (1nm?) /length
  control in cavity
• Extraction line
• Both Europe US groups have and RD effort.
• Europe use a cavity to reduce laser power
• US full power laser design
• US laser commissioning 20 J pulses at 10 Hz /
  Full power next year
• interferometery for alignment
• ½ size focusing optics setup in lab
• beam-beam deflection feedback system study
• PC testbed at SLAC? Proposal under preparation
• Europe study cavitiy option
• Make 19 size test cavity? Wait for
  funding/technology decision?

Funding is an issue to continue RD!
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Interferometric Alignment System Testbed at LLNL
J. Gronberg

• Half-scale prototype of optics / alignment system
  to test mirror quality and alignment scheme
• Optics and laser interferometer currently
  installed

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gg Engineering Test Facility at SLCRevive SLC
and install beampipe with opticsto produce gg
luminosity
Beam Energy DR g?x,y (m-rad) FF g?x,y (m-rad) ?x
/ ?y ? z ?x,y N?
30 GeV 1100 / 50 1600 / 160 8 / 0.1 mm 0.1 1.0
mm 1500/55nm 6.0E9
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G. Klemz
New proposal
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Conclusions

• Lot of activity on gamma-gamma during this
  workshop series
• Good balance found between gamma-gamma specific
  meetings and integration with the other groups
• Good progress on tools/background etc, for
  gamma-gamma studies
• Many detailed studies
• The light Higgs results confirmed and extended ?
  ????/??? 2
• Higgs channels in WW,ZZ studied ? ????/???
  3-10
• H/A study confirms reach for high masses, beyond
  ee-
• CP, Higgs spin etc ? studies starting
• Detailed study of the TGCs ? ? measurement
  competitive with ee-
• First results on SUSY and Extra
  Dimensions/alternatives
• ? explore during the continuation of the
  workshop
• Confirms ??/e? as an exciting option for
  a LC !
• Progress also with hardware plans (PC
  testbed/Berlin studies)

Big thanks to all participants, particularly the
Warsaw and Zeuthen Groups