1 / 15

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. 1. HERA Perfomance. Luminosity. HERA– I : 1992 - 2000 ~ 120 pb -1 per experiment, mostly e + p

clem
Download Presentation

Non-SUSY Searches at HERA

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 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

  2. 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

  3. 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

  4. 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

  5. Model – independent Search Event Classes Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 5

  6. 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

  7. 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

  8. Contact Interactions • Measurement via 2-angle method: • Resolution << Binning • Results limited by statistics Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 8

  9. 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

  10. 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

  11. 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

  12. 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

  13. Excited electrons • Full statistics: No excess seen Peter Schleper, Hamburg University SUSY07 Non-SUSY Searches at HERA 13

  14. 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

  15. 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

More Related