EW at HERA
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Transcript of EW at HERA
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 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 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 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 20
Single TOP results from H1
Slight excess in the muon and electron channels