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Experimental Studies of Strong Electroweak Symmetry Breaking in Gauge Boson Processes

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This study investigates weak boson scattering processes and their sensitivity to quartic anomalous couplings. It explores various configurations of collider physics, including polarization states of the electron-positron beams and the impact of initial state radiation on signal detection. Utilizing advanced simulation techniques, the research evaluates the total cross-section dependency on anomalous couplings, analyzes event distributions, and establishes precision limits for electroweak interactions at energy levels up to 1 TeV. These findings represent significant strides in understanding electroweak symmetry breaking dynamics.

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Experimental Studies of Strong Electroweak Symmetry Breaking in Gauge Boson Processes

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  1. Experimental studies of Strong Electroweak Symmetry Breaking in gauge boson scattering and three gauge boson production P.Krstonosic Work done by : K. Mönig, P.Krstonosic, M. Beyer, E. Schmidt, H. Schröder LCWS 05

  2. Introduction • All possible weak boson scattering processes and sensitivity to the quartic anomalous couplings • deff. remark LCWS 05

  3. Processes • Polarization 80%L for e- , 40%R for e+ for the beams • Initial state radiation taken into account • single weak boson production as background • e- e- option considered new LCWS 05

  4. Sensitive variables • dependence of the total cross section on anomalous couplings • ( only one varied at a time) , and sensitivity of variables used in the • fit ( total mass , absolute production and decay angle ) LCWS 05

  5. Simulation & Fit • Full 1ab-1 event sample generated with WHIZARD • Hadronization with PYTHIA followed by SIMDET fast simulation • Matrix element calculation with O'mega used for calculating event weights in the form : where R is the ratio of the matrix element to the SM one • Sensitivity is evaluated with Binned Likelihood Fit SM sample, • After separate analysis for signal processes double counted events were assigned to one sample according to mass distance from M(V)+M(V) mass (V=W or Z) LCWS 05

  6. ISR • example of ISR influence on result • ( 800GeV W+W- ) Fit for only signal process ( no background) LCWS 05

  7. Analysis 1TeV 800GeV • polar angle of final state lepton • 30% reduction within detector acceptance when going from 0.8->1TeV • reconstructed mass distribution for W (blue) and Z (red) at 1TeV (Durham) LCWS 05

  8. Analysis all • realistic anti b-tagging used • ( ZVTOP ) for WW signal b-tagg • significant reduction of Z • contribution in a W mass • window possible • ( 50% within 70-85GeV as • marked on the picture ) LCWS 05

  9. 800GeV e+e- • comparison with R. Chierci, S, Rosati, M. Kobel LC-PHSM-2001-038 • our result in red , old in black • full line 70%Cl dotted 90%Cl LCWS 05

  10. 800GeV e+e- • result from 1ab-1 sample • change in estimated limits mainly from difference in WW->ZZ limit. combined LCWS 05

  11. 1TeV gain • Improvement in result by going from 800GeV (in green) to 1TeV (in red) • Combined effect of : - signal cross section rise • - s-channel background reduction • - rise of effective rescattering energy LCWS 05

  12. 1TeV e+e- • two parameter contours • ( full line 70%Cl, dotted line 90%Cl) LCWS 05

  13. 1TeV e+e- • Results from 1ab-1 sample • 2D case ( ) • and a full 5D fit LCWS 05

  14. 1TeV e+ e- • result for a 1ab-1 sample from e+e- processes at 1TeV LCWS 05

  15. 1TeV e-e- and combined • in red 1ab-1 e+e- & 350fb-1 e- e- • in blue 2ab-1 e+e- LCWS 05

  16. Feynman diagrams e+e_W+ W_ Z standard model background LCWS 05

  17. Three-body kinematics • momenta • 3 particles x 4 components 12 • energy momentum conservation - 4 • on-shell condition - 3 • axial invariance (-dependence) - 2 • e.g. eZ plane, ZW plane • total 3 • kinematical variables: • spins, 2 d.o.f LCWS 05

  18. Sensitivity • Discretize observable into bins Nijk • Ntheo  Whizard • with n = 2 Mio evts. • Nexp  (Simdet  Pythia)  Whizard • with L = 1000 fb-1 • efficiency 60% • purity 70% LCWS 05

  19. Confidence level contours 5 WWZ 80% e-right polarization WWZ unpolarized 70%Cl 90%Cl 4 WWZ 80% e-right, 60% e+left ZZZ unpolarized preliminary LCWS 05

  20. Summary • Major step towards a full and consistent set of limits done • Confirmed cutoff scale reach above 2.5TeV for isospin conserving case • Triple weak boson production still to come • Interpretation of results in specific physic scenarios in plan LCWS 05

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