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Electroweak precision observables in the LHC epoch

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.

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Electroweak precision observables in the LHC epoch

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

  2. 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.

  3. Examples of new physics discovered with EWPO • Nν =2.984 ± 0.008 • Mt=172 + 10.2- 7.6 GeV

  4. Examples of new physics discovered with EWPO

  5. Examples of new physics discovered with EWPO

  6. Suggested parameters E GeV 46+46 82+82 R=2,8 km (UNK tunnel C=20,7 km) Beam-beam tune shift ξy 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 1034 cm-2s-1 0,5 0,2 Dedicated Z - factory 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

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

  8. Longitudinal polarization Longitudinal polarization at LEP D.Treille C.Bovet, H.Burkhardt, F.Couchot et al • Transverse polarization can be transformed to longitudinal one • Experiment has to be inclined by 10 • Some loss of luminosity: 5·1033 cm-2s-1 → 1·1033 cm-2s-1

  9. Statistics • Z peak 0∫5yearsL dt = 2.5·1041cm-2 NZ=1010 • Longitudinal polarization in Z peak 0∫1yearL dt = 1·1040cm-2 NZ=4·108 • WW at threshold (164 GeV) 0∫2yearsL dt = 4·1040cm-2 NWW = 2.5·105 From P.Wells

  10. Z peak • MZ, ΓZ, σhad, Rl, Rb, Rc, AlFB, AbFB, AcFB, Al(Pτ) • Energy calibration:

  11. Systematic errors in E • n ZF goal: δMZsyst< 1 MeV

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

  13. δMZ ≈ 1 MeV δΓZ ≈ 1 MeV δσhad /σhad ≈5·10-4 δRl / Rl ≈ 5·10-4 δRb ≈0,0002 δ Rc ≈0,001 δ AlFB≈0,0002 δAb ≈0,001 δ Ac≈0,002 δ Al(Pτ) ≈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 ZF at Z peak R. Hawkings K. M¨onig. P.Rowson M.Woods

  14. ALR with longitudinal polarization • N=4·108 • P=55% • δL/L= 1·10-4 • δP/P= 1·10-4 ↓ • δALR= 1,6·10-4 (compare: SLD δALR= 2·10-3 ) • δSin2θW = 1/8 δALR = 2 ·10-5 • ALR = 2(1 − 4 sin2 θeff)/(1 + (1 − 4 sin2 θeff)2) Blondel scheme

  15. 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 δMstat= 4 MeV δMEbeam = 5 MeV δM other syst = 5 MeV δ M W≈ 8 MeV

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

  17. EWPO for new physics (2) δsin2θW = 2 ·10-5 → δMH / MH = 5% It requires: δMt<0.4 GeV δΔαhad (MZ)< 0.0001

  18. EWPO for new physics (3)

  19. EWPO for new physics (4)

  20. Decays V.Obraztsov Y.Khokhlov • Z →γγγ • FCNC: Z →eμ, eτ, μτ, s̃b • Z →W f ̃f • Z →Q̃Q γ, Pγ • γγ →x • Nb̃b= 1.5·109 • Z` M> 200÷1400 GeV → θmix < 10-3 →

  21. ZF vs GigaZ ZF GigaZ Cost x << 10x Lum [cm-2s-1] 5·1033 ≈5·1033 ∫Lum dt [cm-2] 5·1041 >> 5·1040 δ E [MeV] <1 << >10 Beamstrahlung [MeV] <<1 << >10 Events/bunch ≈10-6 << ≈10-3 Background x < y ↓ ZF !

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

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