Electroweak precision observables in the LHC epoch A.Zaitsev, Protvino Gomel, July 2007

EWPO High precision measurements of EW parameters give the way to probe new physics via virtual effects of additional objects. Most of EW precision data were obtained at LEP and SLD. The progress in accelerators and detectors gives the chance for construction of dedicated Z-factory. It can provide us with information on new physics complimentary to that at LHC.

Examples of new physics discovered with EWPO N ν =2.984 ± M t = GeV

Examples of new physics discovered with EWPO

Dedicated Z - factory Suggested parameters E GeV R=2,8 km (UNK tunnel C=20,7 km) Beam-beam tune shift ξ y 0,05 0,09 Beta function β* y = 0,02 m Synchrotron power P=60 MW Energy loss per turn GeV 0,14 1,4 Luminosity cm -2 s -1 0,5 0,2 LEP D Brandt, H Burkhardt, M. Lamont, S Myers et al e+e- COLLIDER IN THE VLHC TUNNEL A.Barcikowski, G. Goeppner, J. Norem et al A Z-factory in the VLLC tunnel E. Keil ZF A.Skrinsky et al

Transverse polarization Transverse polarization at M Z can reach 55% with polarization time t<1h. It gives excellent possibilities for precise energy calibration From R.Asmann Polarization at LEP CERN 1988

Longitudinal polarization Transverse polarization can be transformed to longitudinal one Experiment has to be inclined by 1 0 Some loss of luminosity: 5·10 33 cm -2 s -1 → 1·10 33 cm -2 s -1 Longitudinal polarization at LEP D.Treille C.Bovet, H.Burkhardt, F.Couchot et al

Statistics Z peak 0 ∫ 5years L dt = 2.5·10 41 cm -2 N Z =10 10 Longitudinal polarization in Z peak 0 ∫ 1year L dt = 1·10 40 cm -2 N Z =4·10 8 WW at threshold (164 GeV) 0 ∫ 2years L dt = 4·10 40 cm -2 N WW = 2.5·10 5 From P.Wells

Z peak M Z, Γ Z, σ had, R l, R b, R c, A l FB, A b FB, A c FB, A l (P τ ) Energy calibration:

Systematic errors in E n ZF goal: δM Zsyst < 1 MeV

Monitoring ZF goal: Absolute error: δL ≈ 3·10 -4 Relative error: δL ≈ 1·10 -4

ZF at Z peak δM Z ≈ 1 MeV δΓ Z ≈ 1 MeV δσ had /σ had ≈5·10 -4 δR l / R l ≈ 5·10 -4 δR b ≈0,0002 δ R c ≈0,001 δ A l FB ≈0,0002 δ A b ≈0,001 δ A c ≈0,002 δ A l (P τ ) ≈0,001 At ZF the precision in EW parameters can be improved significantly in comparison with LEP/SLD owing to: 3 orders of statistics Advanced technologies in detectors (especially in vertex detectors) and data analysis Better energy calibration R. Hawkings K. M¨onig. P.Rowson M.Woods

A LR with longitudinal polarization N=4·10 8 P=55% δL/L= 1·10 -4 δP/P= 1·10 -4 ↓ δA LR = 1,6·10 -4 (compare: SLD δA LR = 2·10 -3 ) δSin 2 θ W = 1/8 δA LR = 2 ·10 -5 A LR = 2(1 − 4 sin 2 θ eff )/(1 + (1 − 4 sin 2 θ eff ) 2 ) Blondel scheme

W mass A The crossection of WW pair production near the threshold in the region of 2E=164 GeV is very sensitive to W mass: dσ/dM / σ = 0,5 GeV -1 δM stat = 4 MeV δM Ebeam = 5 MeV δ M other syst = 5 MeV δ M W ≈ 8 MeV

EWPO for new physics (1) S T J. Erler, S.Heinemeyer, W. Hollik, G.Weiglein, P.M. Zerwas

EWPO for new physics (2) δsin 2 θ W = 2 ·10 -5 → δM H / M H = 5% It requires: δM t <0.4 GeV δΔα had (M Z )<

EWPO for new physics (3)

EWPO for new physics (4)

Decays Z → γγγ FCNC: Z → eμ, eτ, μτ, s̃b Z → W f ̃f Z → Q̃Q γ, Pγ γγ → x N b̃b = 1.5·10 9 Z` M> 200÷1400 GeV → θ mix < → V.Obraztsov Y.Khokhlov

ZF vs GigaZ ZF vs GigaZ ZF GigaZ Cost x << 10x Lum [cm -2 s -1 ] 5·10 33 ≈ 5·10 33 ∫ Lum dt [cm -2 ] 5·10 41 >> 5·10 40 δ E [MeV] 10 Beamstrahlung [MeV] 10 Events/bunch ≈10 -6 << ≈10 -3 Background x < y ↓ ZF !

Tunnel Tunnel 20.8 km circumference ~50 m underground 5.1 m diameter