1 gamma-gamma physics group report a.de roeck cern
TRANSCRIPT
1
Gamma-gamma Physics Group Report
A.De RoeckCERN
2
This meeting
Sessions
• Gamma gamma session (3 talks) (including a Report from LCWS02 by M Krawczyk)• Common session with QCD (1 talk)• Common session with Higgs (6 talks)• Common session with EW ( 2 talks)
• Jeju Photon Collider option discussion (Higgs group)– Physics case for PC has confirmed/strengthened (Higgs properties measurements/Heavy Higgs
production) – Must do appropriate R&D to keep the possibility of a PC
3
Studies Reach Maturity
• Aim: Level of detail in as good or better than in e+e-– SIMDET simulation (~e+e- detector/ see K. Moenig).
Brahms?– Real Luminosity spectra/polarization used– B search using ZVTOP– Adding overlap events – QCD backgrounds in NLO– QCD Monte Carlo tuning to existing data– Cross checks for key processes (Higgs production)– Direct contact & exchange with the NLC studies/exchange
tools
• More work still needed on– Luminosity/polarisation measurement (& corresponding
syst.)– Final design of IP/vertex detectors ( backgrounds)
4
AMEGIC++ for
S. Schumann, F. Kraus
Resolved
Direct
Event generator AMEGIC++
5
AMEGIC++ for
• Matching ME to parton showers• NLO • Underlying event structure• Hadronization and fragmentation
• Specific for : Photon decomposition & structure
Expect first version (for lepton final states) next month/Hadrons early next year.!Useful for background studies to Higgs!
6
Monte Carlo Tuning
JetWeb hep-ph/0210404 http://jetweb.hep.ucl.ac.uk J Butterworth et al
M.Wing
‘fit’ MCparametersto data fromLEP, HERA& Tevatron
7
MC Tuning
have to check effects on our backgrounds
8
9
• Update:Use SIMDET + ZVTOP B finder
SM Higgs analyses
P. Niezurawski
81%
1.8%
10
Using NLO backgrounds (Jikia…) Fragmentation questions?
Systematics…??
SM Higgs analyses
1 year/84 fb-1
11
SM Higgs analyses
events 2900N
events 3370 N
bkg
sig
ccbb
2.3%NN
N
)bb)BR(h(hbb)BR(h(h
bobs
obs
γγΓ
γγΓΔ
Pythia reweighted with NLO cross sectionsZVTOP Tagging optimization still ongoing (presently lower than prev. analysis)
A. Rosca
. fb 80 1-L
12
Overlap events1.5 central high energy events for L(z > 0.8zmax)
~ 1.1 .1034 cm-2 s-1
•Files for TESLA have been prepared/SIMDET adapted to use overlays
e+e- and files So far catalogued on the CLIC page //clicphysics.web.cern.ch/CLICphysics 200 & 500 GeV files available file contains 5000 events•Selection events: W2 > 5 GeV2 , tracks: Pt> 150 MeV, > 80 mrad photon polarization not taken into account
Effect on the measurement? Work in progress…
13
SM Higgs analyses
14
H/A Higgs
D. Asner/J. Gunion(LCWS02)
Need few years to Close the wedge
Need also Europeanstudy
15
Low Mass Charged Higgs
V. Martin
Using H decaysFull simulation
Relative lowefficiency after cuts: 2.5 %
What can a PC contribute?
16
2HDM model
M. Krawczyk
17
M. KrawczykR. Godbole
Invitation
Upcoming initiative…
18
CP studies via tt
R. Godbole et al.hep-ph/021136& LCWS02
Construct combinedasymmetries fromintial lepton polarizationand decay lepton charge
Done with realisticspectra etc., but needsstudy with simulation
19
Trilinear Gauge couplings in e
D. Anipko
Analyse d2/dp dcose
CompHEP
20
Fitting results of the fit of Fitting results of the fit of andand for for ± 1 photon polarization state – single ± 1 photon polarization state – single
and two parameter fit for real (and two parameter fit for real (ee ) mode ) mode
REAL MODE
1 par. fit
ECM = 450 GeV, L = 110 fb-1
J = +1 J = -1
L 1% 0.1% accur. 1% 0.1% accur.
·10-3 3.4 1.0 0.5 9.7 1.1 0.5
·10-3 1.6 1.5 1.5 4.6 4.4 3.82 par. fit
·10-3 5.1 1.1 0.5 9.7 1.1 0.6
·10-3 2.3 1.6 1.6 4.6 4.6 4.6
REAL MODE - pure e-mode, known beam directions
Trilinear Gauge couplings in e
ee WW , , hadronic decay channel/total and differential cross sectionshadronic decay channel/total and differential cross sections
J Sekaric & K. Moenig
21
comparison of the single parameter fit for comparison of the single parameter fit for ee , ,
-, and -, and ee--ee++ - colliders - colliders
Ee= 450 GeV
L=110 fb-1
E= 400 GeV
L=110 fb-1
Eee= 500 GeV
L=500 fb-1
L 0.1% 0.1%
·10-4 10 / 9.8 6.7 3.1
·10-4 15 / 5.8 6.0 4.3
sensitivity to WW only! - , ~ 10-3
22
Most important processeshep-ph/0103090
Added since then: Non-commutative measurements, e for ED’s,Light gravitinos, Radions, H?, HH+H-?…
Higgs
Susy
Tril/quart.
Top
QCD
Any Volunteers?? Being done/ready promised
23
Plans
• Finalize current analyses, particularly higgs sector– If IP studies in near future will require changes need to
know this asap• High priority to start H/A & SUSY particle analysis, CP
studies• Use synergy with NLC group/exchange of tools• Indian group starts studying ED’s in and e (R. Godbole
et al.). Expect first results by Amsterdam• Additional meeting before Amsterdam: February 13 @ CERN • Plan to write up summary of the PC studies for Amsterdam• At Amsterdam: Plan a panel discussion on a PC collider
24
NLC studies overview
25
D. Miller Determining the Spin of the H in collisions
26
H/A higgs
Can a photon collider close the wedge?Cross section gets small For M(H/A) > 600 GeV
J.Gunion: 2-4 years needed
CP studies
Expect need to run of photon colliderfor several yearsif the physics scenario warrants it!
27
Luminosity and spectra
Usable in eventsimulation(Telnov/Ohl/Zarnecki)Pandora
For TESLA…
Z=W/2Ebeam
28
Cross sections
29
B-tagging
IP
B
D
Primary vertex
Secondary vertex
Tertiary vertex
• Reconstruction of the vertex using a topological vertex technique (ZVTOP).
cc
qlight
bb
30
The photon collider case• Advantages
– Large cross sections (e.g. WW production cactor 20-40 times)– Large circular polarization e-e- beams (~80%) (90-95% in peak)– Linear polarization (CP filter)– Extended kinematic range for some new particles
• S-channel production for H,… /association e.g. slepton lepton+0
– Sometimes different couplings probed (no “Z” effects)• Issues
– Luminosity spectrum spread (not monochromatic, but much better than LHC). How precise can we measure the spectrum/luminosity?
– Luminosity typically factor 3 lower compared to e+e-(but yet not at limit)
– Needs R&D to proof it works as expected. plans– More complicated IR– Debate of backgrounds and its implication on detector not yet
finalized– Only few processes so far studied in (almost) all experimental details,
most important one Higgs
31
The light Higgs
“State of the art””(M. Krawczyk)
All background under control? B-tagging different in ?
32
Background studiesFrequently asked question: same b-tagging efficiency as in e+e- case?
K. Moenig et al.: backgrounds studied for TESLA IP layout
Study beam related background
# of hits in the layers of the pixelDetector per bunch crossing
Incoherent pair production: essentiallythe same as for e+e-
Coherent pair production: under study
Neutrons?
Will be able to answer this question soon
33
Is a photon collider a hadron collider?
•The QCD background in a collider can be large Eg. for Lgeom ~ 1035 cm-2 s-1, 400 nb cross section 3 events/bunch crossing
–Many events boosted and/or low mass: no problems–V. Telnov (TESLA TDR appendix): 1.5 central high energy events for L(z > 0.8zmax) ~ 1.1 .1034 cm-2 s-1
# of jets (Et > 5 GeV)
> 80 mrad > 250 mrad
10-20 tracks/event<ET> few GeV, tails up to 20-30 GeV Looks not so bad!(ADR, ST Malo meeting)
Common study withtheorists and NLC groups starting
NO !
34
R&D program
Europe: R&D for lasers in IP (10% size prototype cavity planned)US: Laser development at LLNL Plan for SLC photon collider testbed at SLAC (means reactiviating SLC/ Workshop at SLAC Nov 21-23 ‘02
Conclusion: Photon collider will enrich the program of an e+e- machine We cannot afford NOT to study it !