14-18 November, Praha ECFA/DESY Linear Collider Workshop 1
TRILINEAR GAUGE COUPLINGS AT PHOTON COLLIDER - e mode
TRILINEAR GAUGE COUPLINGS AT PHOTON COLLIDER - e mode
DESY - ZeuthenDESY - Zeuthen
Klaus Mönigand
Jadranka Sekaric
ECFA/DESY Linear Collider Workshop 214-18 November, Praha
INTRODUCTION1.1. signal to background separation studysignal to background separation study
((ee WW , , hadronic decay channel)hadronic decay channel)2.2. observables sensitive to trilinear gauge couplingsobservables sensitive to trilinear gauge couplings
- higher order radiative corrections :- higher order radiative corrections : ggWW/16/1622 ~ 10~ 10-3-3 , , (3-6) (3-6)
- - same order deviationssame order deviations of the TGCs might arise if the SM of the TGCs might arise if the SM is the low energy limit of a larger theory is the low energy limit of a larger theory test of EW test of EW theory, probe of some possible extensions theory, probe of some possible extensions new new physics beyond the SMphysics beyond the SM manifest itself :manifest itself :
- new particles produced at a collider - new particles produced at a collider - precision measurements of deviations from its SM values - precision measurements of deviations from its SM values (anomalous TGC)(anomalous TGC)
3.3. preliminary fitting resultspreliminary fitting results of parameters of parameters and and (two (two methods)methods)
ECFA/DESY Linear Collider Workshop 314-18 November, Praha
EVENT SELECTIONTOOLSTOOLS::
PYTHIAPYTHIA event generator event generator
SIMDETSIMDET V3V3 detector simulation detector simulation sample of 10sample of 1055 mixed signal and background events, generated mixed signal and background events, generated
with PYTHIA at with PYTHIA at EECM CM = 450 GeV, variable photon energy = 450 GeV, variable photon energy
spectrum, without beam polarization and anomalous couplings spectrum, without beam polarization and anomalous couplings response of a detector simulated with SIMDET V3 (acceptance response of a detector simulated with SIMDET V3 (acceptance
effects)effects) WW reconstructed from hadronic decays ( reconstructed from hadronic decays (WW qqqq (2jets)) (2jets))
ECFA/DESY Linear Collider Workshop 414-18 November, Praha
e
e
e
Z°
W
e e
W
e e
q
q
qqqq
breamstrahlungbreamstrahlung
q
ee WW
t-channelt-channel
Channel’s contribution:Channel’s contribution:
ee eZ eZ00
s-channels-channel
t-channel exchange dominates (for the signal) t-channel exchange dominates (for the signal)
e
e e
Ws-channels-channel
ECFA/DESY Linear Collider Workshop 514-18 November, Praha
• high W production cross-section (high W production cross-section (~ pb)~ pb) allows us allows us to efficiently separate signal from backgroundto efficiently separate signal from background ( ( ee eeWW eZeZ00eqqeqq (QED)(QED) qq qq ))
Applied cuts:Applied cuts:
• acc. detector acc. detector angle - 7angle - 7°°
• number of number of energy flow energy flow objectsobjects**
• W energyW energy
• W massW mass
NEFO
EW
* electrons, photons, muons, charged and neutral hadrons and unresolved clusters that
deposited energy in the
calorimeters
ECFA/DESY Linear Collider Workshop 614-18 November, Praha
ee eeW W eeqqqq ee eZeZ00eqqeqq qqqq
High High efficiency efficiency with low with low backgroundbackground
MW
θ°
ECFA/DESY Linear Collider Workshop 714-18 November, Praha
SENSITIVE OBSERVABLEStotal and differential production cross-section
sensitive to anomalous coupling
W production angle (polar angle - cosθ) W decay angle (between the quark and the total
momentum of quark pair – cosθ1)
e
z
x
yq
q
eW
1
ECFA/DESY Linear Collider Workshop 814-18 November, Praha
TOOLS analytic formula for total (differential) cross-
section (A. Denner, A.Dittmaier, Nucl.Phys. B398 (1993)239
helicity amplitudes for different initial photon and final W states (E.Yehudai, Phys.Rev. D11(44)1991))
differential cross-section distribution over the decay angle (Bilenky at al.,Nuc.Phys. B(409) (1993)22
WHIZARD Monte Carlo tree–level generator (W.Kilian,University of Karlsruhe)
ECFA/DESY Linear Collider Workshop 914-18 November, Praha
1.1. Analytic formulaAnalytic formula
DCS in presence of anomalous DCS in presence of anomalous coupling for Jcoupling for J = = ± ± 11 statestate
normalized to its SM valuenormalized to its SM value
DCS for JDCS for J = = ±1 state±1 state in SM in SM
ECFA/DESY Linear Collider Workshop 1014-18 November, Praha
WW’s polarization fraction as a function of coupling ’s polarization fraction as a function of coupling parameter deviationparameter deviation
- production of longitudinal - production of longitudinal WWs for Js for J = -1 suppressed in SM = -1 suppressed in SM
ECFA/DESY Linear Collider Workshop 1114-18 November, Praha
Deviation effects of Deviation effects of WWLL’s in presence ’s in presence
of anomalous couplingof anomalous coupling
ECFA/DESY Linear Collider Workshop 1214-18 November, Praha
1
2
1
2
1
cos1)(cos
cos1)(cos2
1
4
3
)(cos)(cos d
d
d
d
dd
d LT
n
i
n
j L
normji
normjiNjiN ACCACC
1 12
2
2
2
2
)(
)1(),(
)),(),(( )(0
constant ionnormalizat-
meas. luminosity on error- Δ
events of number-
norm
LN
jiNji
jiACCjiNjiN
ACC
ACC
0
0
),(),(
),(),(),(
2D acceptance function2D acceptance function
ECFA/DESY Linear Collider Workshop 1314-18 November, Praha
Fitting results of the fit of Fitting results of the fit of andand for for ± 1 photon ± 1 photon
polarization state – single and two parameter fit for real polarization state – single 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
ECFA/DESY Linear Collider Workshop 1414-18 November, Praha
Fitting results of the fit of Fitting results of the fit of andand for for ± 1 photon ± 1 photon
polarization state – single and two parameter fit for polarization state – single and two parameter fit for parasitic (parasitic (ee ) mode ) mode
2 par. fit
·10-3 8.5 1.1 0.5 9.7 1.1 0.6
·10-3 6.0 2.8 2.8 4.9 4.9 4.9
PARASITIC 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 3.7 1.0 0.5 9.7 1.1 0.5
·10-3 2.6 2.6 2.4 4.9 4.7 4.0
PARASITIC MODE - running in -mode, could be considered as a background, unknown beam directions
ECFA/DESY Linear Collider Workshop 1514-18 November, Praha
2.2. Reweighted eventsReweighted events
WHIZARDWHIZARD Monte Carlo generator Monte Carlo generator for 10 for 1055 ( (ūūdd) pairs ) pairs at at EECM CM = 450 GeV, fixed photon beam energy, polarized = 450 GeV, fixed photon beam energy, polarized
beams, anomalous couplings - beams, anomalous couplings - NNevev normalized to previous normalized to previous
oneone
matrix elements for different matrix elements for different and and values generatedvalues generated
Monte Carlo events reweighted with function Monte Carlo events reweighted with function RR(() = 1 + A·) = 1 + A· + + BB·· + C·( + C·())22 + D·( + D·())22 + E · + E · 2D 2D cross-sectioncross-section distributions over distributions over coscosθθ and and coscosθθ11 are are fitted fitted
n
i
n
j L
normji
normjiNjiN ACCACC
1 12
2
2
2
2
)(
)1(),(
)),(),(( )(0
ECFA/DESY Linear Collider Workshop 1614-18 November, Praha
- single parameter fit
- two parameter fit
REAL MODE
ECM = 450 GeV, L = 110 fb-1
J = +1 J = -1
L 1% 0.1% accur. 1% 0.1% accur.
·10-3 2.49 0.98 0.43 2.22 0.95 0.41
·10-3 0.58 0.58 0.58 0.79 0.79 0.78
·10-3 2.74 1.00 0.43 2.17 0.95 0.41
·10-3 0.64 0.59 0.59 0.79 0.79 0.79
- agreement within 10% with previous results for and more sensitive in determination – differs for a factor ~3 (‘better’) – still not understood
- single and two parameter fit in a good agreement
ECFA/DESY Linear Collider Workshop 1714-18 November, Praha
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
ECFA/DESY Linear Collider Workshop 1814-18 November, Praha
SUMMARYW production in ee collider at high energies is
sensitive process to the possible scenario of EWSB
efficient signal to background separation sensitivity to WW only! - , ~ 10-3
agreement in determination for two different fitting procedures FUTURE PLANS
low energy qq background not included yet signal to bck by WHIZARD (implantation of variable
energy spectrum for photon beam) fitting procedure with variable energy spectrum