Non susy searches at hera
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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

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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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