Luca Stanco - Padova EW and NP at HERA, Photon 2009 1

EW at HERA

Luca Stanco – INFN Padovaon behalf of ZEUS and H1 collaborations

and “RELATED” NEW PHYSICS

- HERA: a QCD and EW machineResults on:- EW constraints- Isolated Leptons- Single TOP

Luca Stanco - Padova EW and NP at HERA, Photon 2009 2

HERA: a collider e-p

H1

ZEUS

Last Fill the 30th June 2007

0.5 fb-1 per exp.: e+p, e-p, LowEnergyRange, MER

1993-2007

HER

A-II

HERA-I

Luca Stanco - Padova EW and NP at HERA, Photon 2009 3

HERA: the QCD machine

Glu

ons an

d

QCD

dyn

amics

For Q2 ≈ M2Z,M2

W study also EW interactions:

CC double diff. cross-section

Beam Polarization QPM Structure Functions

Luca Stanco - Padova EW and NP at HERA, Photon 2009 4

HERA-II feature: Polarization

Luca Stanco - Padova EW and NP at HERA, Photon 2009 5

Q2 ∼ 1/the scale of the interactioncorresponds to the spatial resolution at which the proton structure is probed

Luca Stanco - Padova EW and NP at HERA, Photon 2009 6

ElectroWeak unification: status-of-the-art

Neutral e-p (ZEUS publ., H1 prel.)Current e+p (ZEUS prel., H1 prel.)

Charged e-p (ZEUS publ., H1 prel.)Current e+p (ZEUS prel., H1 prel.)

-exchange

M2Z and M2

W dominateexhanges

( corrected for the Polarization effects )

Luca Stanco - Padova EW and NP at HERA, Photon 2009 7

NC and Structure Functions: Parity Violation test

Luca Stanco - Padova EW and NP at HERA, Photon 2009 8

Weak Interaction check with Polarization (CC)

V-A chiral structure

(ZEUS preliminary 2007)

WR>208 GeV

Luca Stanco - Padova EW and NP at HERA, Photon 2009 9

Weak Interaction check with Polarization (NC)

Asymmetry proportional to vector coupling

Parity Violation size,

demonstrated down to 10-18 m

Luca Stanco - Padova EW and NP at HERA, Photon 2009 10

DGLAP fits for QCD-EW: PDFs’ and uv-quarks couplings

- Simultaneous test of the EW and Strong sectors of SM

- Best determination of u-coupling to Z

- Competitive with Tevatron and LEP results

Luca Stanco - Padova EW and NP at HERA, Photon 2009 11

Isolated high-pT leptons: status-of-the-art

Final analysis from H1 and ZEUS on Electron and Muon leptonsH1 looked also at the Tau leptons: challenging, large background

nice Jacobian peaks,however at hight pT…

(combined in progress)

Luca Stanco - Padova EW and NP at HERA, Photon 2009 12

Gerard Brandt at DIS09

H1:

Luca Stanco - Padova EW and NP at HERA, Photon 2009 13

Anomalous Single TOP production at HERA

Final results from H1 (HERAII: 474 pb-1), HERAI+II in DESY-09-50ZEUS preliminary: 277 pb-1 (HERAII), combined with HERAI (120 pb-1)

Neglet c and Z couplings.

Sensitive to u (valence) and anomalous exchange

Intrinsic background from SM production of W (lepton decay)

Search for signal in muon, electron, hadron channels

Luca Stanco - Padova EW and NP at HERA, Photon 2009 14

No excess limits, H1: < 0.25 pb, ktu < 0.18, ZEUS: < 0.13, ktu < 0.13(slight excess)

Stefano Antonelli at DIS09

Luca Stanco - Padova EW and NP at HERA, Photon 2009 15

Conclusions

• Many EW checks,Universality, Chiral Structure, Parity Violation• Single W production, measured,

intriguing signal left at hight pT

• Anomalous Single TOP production, SM checked (Colliders complementarity)

• H1 and ZEUS exploit most of HERA DATA for EW studies• Unique HERA results done and undergoing

BIG thanks to HERA !!

Luca Stanco - Padova EW and NP at HERA, Photon 2009 16

Backup Slides

Luca Stanco - Padova EW and NP at HERA, Photon 2009 17

Chiral Structure of CC, by ZEUS

DESY-08-177

Total cross-sectionvs Electron Polarization

provides striking evidence

Luca Stanco - Padova EW and NP at HERA, Photon 2009 18

Isolated Lepton yield

Luca Stanco - Padova EW and NP at HERA, Photon 2009 19

Single TOP production at HERA in the SM

Luca Stanco - Padova EW and NP at HERA, Photon 2009 20

Single TOP results from H1

Slight excess in the muon and electron channels

Luca Stanco - Padova EW and NP at HERA, Photon 2009 21

Single TOP results from ZEUS

Muon channel