trilinear gauge couplings at photon collider - e mode

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)


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))


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


• 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


ee eeW W eeqqqq ee eZeZ00eqqeqq qqqq

High High efficiency efficiency with low with low backgroundbackground

MW

θ°


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


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)


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


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


Deviation effects of Deviation effects of WWLL’s in presence ’s in presence

of anomalous couplingof anomalous coupling


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


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


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


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


- 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


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


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

trilinear gauge couplings at photon collider - e mode

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