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SUSY: RpV with ’. di-electrons events

SUSY: RpV with ’. di-electrons events. Auguste BESSON (ISN-Grenoble) SUSY framework Signal and topology Background Expected results Conclusion. SUSY framework. mSUGRA model : m 0 , m 1/2 , A 0 , tan  , Sign  R-parity violated : Double production in Rp conservated

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SUSY: RpV with ’. di-electrons events

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  1. SUSY: RpV with ’. di-electrons events Auguste BESSON(ISN-Grenoble) • SUSY framework • Signal and topology • Background • Expected results • Conclusion. New Phenomena, July 25th 2001.

  2. SUSY framework • mSUGRA model : m0 , m1/2 , A0 , tan  , Sign  • R-parity violated : • Double production in Rp conservated • Decay of LSP via RpV. • One dominant coupling : L : left-handed lepton doublet Q : Quark doublet D : anti-quark singlet New Phenomena, July 25th 2001.

  3. Signal topology with ’122 • Vertex : • LSP decay with : • ’ can be small Without decreasing the signal. New Phenomena, July 25th 2001.

  4. Signal topology (2) • Final state. 2 LSP decay :  2 like sign leptons with high pT + 4 jets + small missing Et. • Branching ratios of LSP  charged lepton :  depends strongly on Sign  . ( and m0 , m1/2, tan  ) • Example : Br.ratio very small for  > 0 .  some regions of the parameters space will be difficult to reach. New Phenomena, July 25th 2001.

  5. Background • 2 like sign electrons + 4 jets + small missing Et. • t-tbar :  6.5 pb • Z ee : • 20 < pT < 60 : 139 pb • 60 < pT < 120 : 165 pb • 120 < pT : 1.9 pb • Z  : • 20 < pT < 60 : 137 pb • 60 < pT < 120 : 164 pb • 120 < pT : 1.9 pb • WW/ZZ/ZW  leptons : 7 pb, 0.9 pb, 2 pb • W/Z + jets. • QCD with pT > 10. + e fake :  600 pb • Misidentification probability of the sign of the electrons ? • e fake probability ?  10-4 Need further studies. New Phenomena, July 25th 2001.

  6. Very preliminary study with SHW/PGS • SCAN in the SUGRA parameters space. • m0 : 50 to 500 step of 50. • m1/2 : 80 to 220 step of 10. • A0 : 0 • Tan  : 5 • Sign  : +1, -1. • 1000 events per point. New Phenomena, July 25th 2001.

  7. Trigger and events selection • Very simple selection: • 2 like sign electrons • pT > 10 GeV ;  < 1.0 • Jets : • pT > 10 GeV ;  < 2.0 • Invariant mass of e-e : not between 80 and 100 GeV. New Phenomena, July 25th 2001.

  8. Cross-sections m 0 m 0 m1/2 m1/2 New Phenomena, July 25th 2001.

  9. Efficiencies Very low efficiency (branching ratios of LSPelectrons small) m1/2 m1/2 m 0 m 0 New Phenomena, July 25th 2001.

  10. Efficiencies (2) • 20k to 50k events for each background. • No Bkgd events survived to the like sign leptons cuts. • The most difficult to estimate is QCD + efake backgd. • Very rough estimate of efficiences but promising results. New Phenomena, July 25th 2001.

  11. Exclusion contours • Very preliminary : • L = 200 pb-1 • 90% Conf. level. • Bakgd studies is only beginning. •  > 0 difficult to exclude. New Phenomena, July 25th 2001.

  12. Run I Exclusion contour for Sign  < 0 and tan  = 2 and 6. PRL 83, 4476 (1999) New Phenomena, July 25th 2001.

  13. Conclusion • Thanks to like sign dilepton cut : Exclusion contours should be improved significantly even with 100 or 200 pb-1. • For more confident results : Need to use full reconstruction and PMCS. New Phenomena, July 25th 2001.

  14. Feynman diagrams New Phenomena, July 25th 2001.

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