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Non-SUSY Searches at HERA. HERA Performance Model –independent Search Contact Interactions Excited Fermions. Peter Schleper Hamburg University SUSY07 July 27, 2007. 1. HERA Perfomance. Luminosity. HERA– I : 1992 - 2000 ~ 120 pb -1 per experiment, mostly e + p

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non susy searches at hera
Non-SUSY Searches at HERA
  • HERA Performance
  • Model –independent Search
  • Contact Interactions
  • Excited Fermions

Peter Schleper

Hamburg University

SUSY07

July 27, 2007

Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 1

1 hera perfomance
1. HERA Perfomance

Luminosity

  • HERA– I : 1992 - 2000
    • ~ 120 pb-1 per experiment, mostly e+p
  • HERA– II: 2003 - 2007

Upgrade: luminosity & polarisation: eL-, eR-, eL+, eR+

Recently: very good conditions

 low background, stable beam conditions

 high data taking efficiencies, low thresholds

 no major problems on central detectors

    • polarisation
      • average ~ 40%
    • electron & positron running
      • ~184 pb-1 e-p
      • ~294 pb-1 e+p
    • Luminosity HERA I & II
      • ~ 478 pb-1per experiment, ~ 90 % at 320 GeV
    • End of HERA running in June, 2007  final data set

Polarisation

Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 2

hera data
HERA Data
  • ~ few 108 ep collisions triggered by H1 & ZEUS
    • Thresholds: 5 … 10 GeV for electrons and jets
    • Luminosity: ~ 1.6 …3.5 % precision
    • Polarisation: ~ 3 ... 5 % precision
    • Calorimeters E-scales: 1 … 3 % for e, jets from kin. Constr.

Inclusive Jet Production

Neutral Current

Charged Current

Q2

Q2

Polarisation

Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 3

2 model independent search h1
2. Model – independent Search (H1)
  • Inclusive search for particles at high PT
  • Electrons ,Photons, Muons, Hadronic Jets, Neutrinos (PTmiss)
  • phase space for all:
    • PT >20 GeV
    • 10o < θ < 140o
  • All combinations: ee, eg,em,ej,….jj, ejj, ejn  event classes
  • Mass and ∑PT(Jacobi-peak)
  • Comparison to SM (LO)

 look for deviations (max. deviations)

  • Statistical interpretation via monte carlo experiments  probability

Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 4

model independent search
Model – independent Search

Event Classes

Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 5

model independent search1
Model – independent Search

Probability of max. deviation for event classes

Precision :

  • Systematics: few %
  • Statistically limited at large M, PT

and large multiplicity

  • Theory: uncertainty large for

multi-jet channel

Distribution for data follows

  • expectation
  • Excellent understanding

of most final states at HERA

Exception: Largest deviation for mjn channel

e+p: H1 observation: 21 / 8.9±1.5events (3.0σ)

ZEUS: no events in excess of SM

e-p:H1 and ZEUS: Agreement with SM  Dedicated search: talk by J. Katzy

Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 6

3 contact interactions zeus
3. Contact Interactions (ZEUS)
  • Standard Model + 4-Fermion interaction

Compositeness

Quark radius

Leptoquark (M> ECMS)

Squarks in RP-viol.

Large Extra

Dimensions

Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 7

contact interactions
Contact Interactions
  • Measurement via 2-angle method:
    • Resolution << Binning
    • Results limited by statistics

Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 8

contact interactions1
Contact Interactions

Data / SM

  • Typical Range of Contact Interaction scales:
  • 2 … 7.5 TeV
  • Improvements: Luminosity: factor 2
  • Polarisation

Q2

Helicity Combinations

Data / SM

Q2

Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 9

leptoquarks indirect
Leptoquarks (indirect)
  • Leptoquark masses excluded for:
    • Indirect search
  • M / λ‘ > 0.3 … 2 TeV
    • Direct searches for peak in Meq
  • M<300 GeV λ < 0.01
  • Squarks in R-parity viol. SUSY:
  • λ‘ijk Li Qj Dk coupling
  • u has same coupling as S1/2
  • same limit applies

~

~

Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 10

large extra dimension
Large Extra Dimension
  • LED’s limited to
    • MS > 0.88 TeV
  • Quark Radius limited to
    • Rq < 0.67 x 10-18 m

Q2

Q2

Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 11

4 excited leptons h1
4. Excited Leptons (H1)

f

compositeness scale

fV

f*

f, f ’ relative strength

for Wm, Bm ,Z

V

  • Effective lagrangian to parameterize compositeness:
  • Spin ½, isospin ½, vector currents as SM leptons
  • Resonance production for masses < ECMS

Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 12

excited electrons
Excited electrons
  • Full statistics: No excess seen

Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 13

excited electrons and neutrinos
Excited Electrons and Neutrinos
  • HERA: Limits typically 220 … 280 GeV for M ~ L/ f
  • LEP: M > 208 GeV direct search
  • LEP/Tevatron: indirect limits for M > 280 GeV

Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 14

5 conclusion
5. Conclusion
  • HERA: final statistics available  0.5 fb-1 per experiment
  • Precision limited by
    • Luminosity for indirect searches: Contact interactions
    • Beam energies for direct searches
    • Experimental errors small in most cases
  • Model –independent search (H1 full statistics):
    • Few % level of understanding of ~ ALL final states at HERA
    • Exception: H1: mjn channel for e+ scattering

ZEUS: not confirmed

  • Contact interactions (ZEUS 285 pb-1):
    • limits on scale ~ 10 x ECMS … up to 7.5 TeV
    • Improvements from luminosity and polarisation still to come
  • Excited Leptons (H1 full statistics):
    • Mass limit ~ 220 … 280 GeV

Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 15

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