HERA p e± 920 GeV 27.6 GeV √s = 319 GeV ep Collider Collider experiments H1 and ZEUS Luminosity: ~200 pb–1 in e–p ~300 pb–1 in e+p √s = 319 GeV p e± 920 GeV 27.6 GeV

NC & CC cross section electron-proton and positron-proton collisions analysed NC: -Z0 interference at high Q2 CC: W+ (W–) exchange in e+ (e–) collisions mainly sensitive to down (up) quark density in the proton high Q2: electro-weak unification

CC polarisation dependence dependence on the longitudinal polarisation of the lepton beam data consistent with linear dependence as expected from Standard Model limit on mass of a right- handed W boson: M > 186 GeV (H1)

Multi-Leptons ZEUS 2 or 3 high PT leptons: ℓ=e, SM signal →ℓ+ℓ– Events at high transverse momentum DESY-09-108 H1+ZEUS combined cross-section of →ℓ+ℓ– at high PT H1+ZEUS at ∑PT>100 GeV

Isolated Leptons / W production Striking signature: ℓ=e, and  in the same event, with high PT At large PTX>25 GeV: ep: 23 / 14.0 ± 1.9 e-p: 6 / 10.0 ± 1.3 W cross section:  = 1.07 ± 0.16 ± 0.08 pb SM prediction  = 1.26 ± 0.19 pb

Single Top Production search in e,,hadronic W decay channel anomalous coupling  PLB 678, 450 (2009) ZEUS (prel.)