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Supersymmetry at LHC and beyond

Supersymmetry at LHC and beyond. ---Ultimate tagets--- Mihoko M. Nojiri YITP, Kyoto University. Why collider ??. Best way to 1. See existence of superpartners 2. Supersymmetric relations 3. Soft mass measurements Understand SUSY breaking mechanism ] Interactions at high scale

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Supersymmetry at LHC and beyond

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  1. Supersymmetry at LHC and beyond ---Ultimate tagets--- Mihoko M. Nojiri YITP, Kyoto University

  2. Why collider ?? Best way to 1. See existence of superpartners 2. Supersymmetric relations 3. Soft mass measurements Understand SUSY breaking mechanism ] Interactions at high scale Impacts on the other physics B, LFV, Dark matter

  3. 1. The existence Large cross section. No SM backgrounds Search up to 2TeV squark or gluino. 1000 events/year for 1TeV squarks and gluinos We should try to extract ALL physics information from THIS experiment! gaugino mass (Not only) famous SPS1a … scaler mass

  4. 2. Supersymmetric relations (I can’t wait until LC operation) • chiral nature • No new dimensionless coupling Fermion-sfermion-gaugino(higgsinocoupling)

  5. chirality and m(jl) distributionsRichardson (2001), Barr(2004), Kawagoe Goto Nojiri(2004) • Chirality of slepton appears in m(jl) distribution • Right handed lepton goes same direction to the jet direction • Right handed anti-lepton goes opposite to jet Charge asymmetry!

  6. MC simulations (left and right sleptons) Kawagoe, Goto, Nojiri(2004)

  7. smuon L-R mixing(Goto’s talk) visible in wide parameter regions Proof of smuon F term mixing Other examples?( m(bb) distribution of gluino->stop top) Hisano, Kawagoe,MMN 2003

  8. Long lived NLSP(~O(10m)) Neutral LSP sfermion<gaugino gaugino<sfermion gaugino<<sfermion degenerated Too heavy Models Gauge mediation Supergravity and the variants M>m M~m M<<m KK 3.Soft mass measurement Collider signature of SUSY “easy” to “hard”

  9. “Easy case”Signature with long lived NLSP • Shorter life time (<O(1cm)) lots of leptons and photons endpoint analysis. • Charged Long Lived NLSP • TOF for charged track • Dt~1ns at 10m-20m • Full reconstruction • Neutral Long Lived NLSP • No track • Fine time resolution at ECAL cDt~3cm at O(1m) • Gravitino momentum and decay position can be solved with the time info (Kobayasi, Kawagoe, Ochi,MMN(2003) Kawagoe’s talk) • No systematic study yet. Hinchliffe and Paige

  10. Long lived NLSP(~O(10m)) Neutral LSP sfermion<gaugino(2 body) gaugino<sfermion(3 body ) gaugino<<sfermion degenerated Too heavy Time delay Signals TOF for charged track Arrival time(photon) Endpoint analysis(Giacomo’s talk) Lepton mode Tau and b modes Jet selection No good ideas 　“Moderatecases”

  11. Summary of endpoint study at SPS1a Based on the endpoint analysis, sparticle masses may be understood very well. The lepton channels are important. LSP mass [dark matter mass Slepton mass, neutralino mass[Dark matter density

  12. Limitations of the end point method • unkonwn LSP momentum • No kinematical constraint even though you know the masses • Waste of statistics • Events off the end points are not used. • Need statistics enough to see the end point. • signals from different cascades to make a single broad end point.

  13. Mass relation method apply mass-shell constraints to solve events • Full event reconstructions! we see peaks. • Use all events for mass and distribution study. • “In principle”, a few events are enough to determine the masses and LSP momentum (up to jet energy resolutions) • Kinematical constraints available. Nojiri, Polesello, Tovey hep-ph/0312318 (Les Houches)

  14. Example of mass relation method 5 Dim mass space M A event<-> 4 dim hypersurface in M gluino mass For simplicity Assume we know mass of sbottom mass Each event corresponds to a curve in the mass plane Two events is enough to give the masses, and LSP momentum. a distribution of the solution in the previous plot

  15. Sbottom mass determination(plot lighter solution for fixed gluno mass) tanb=20 tanb=10 Background level tanb=15 1/3 1/2 485(52)GeV 492(525)GeV 479(532)GeV Sbottom2 contribution Kawagoe, MMN, Polesello…

  16. mSUGRA and 3rd generation mass spectrum • FCNC constraints are weak for 3rd generation. non-universal squark and slepton masses for the 3rd generation. • Yukawa RGE running breaks the universality at at the GUT scale. m(stop,sbottom)<m(1st) • Left-right squark mixing SPS1a tanb=10 sbottom mass 492GeV tanb=20 479GeV • Implication to higgs mass, B physics….

  17. A event aprobability density for true masses(L) log L(1) + logL(2) + log L(3)+ logL(4) = log L(~Dc2) tanb=10 tanb=20

  18. Spin off from the mass relation method Neutralino momentum also solved. Transverse momentum of the 2nd LSP • For the 2nd LSP, transverse • Momentum is known • a event Corresponds to 1 dim line in the • mass space. • Even shorter cascade can be solved. 2nd LSP Total missing momentum reconstructed LSP momentum

  19. New channels using missing pT (hep-ph/0312317,18) Example I chargino reconstruction Example II heavy higgs reconstruction 4lepton channel .

  20. Large tanb gaugino<sfermion squark->gluino jets Then 3 body Losing statistics Tau mode dominate. (giacomo’s talk) All squarks decays into gluino, information loss Jet selection? B modes? “getting more difficult” • Degenerated (no hard jets…)

  21. Handle signal without leptons • Sometimes SUSY signature is not hard leptons. • Still stop, sbottom may be lighter than other sparticles due to top Yukawa RGE SUSY -> events with many b jets. • Gluino decays dominantly into btc- ,bbc0and ttc0 • b tagging efficiency is 60% Looking for non-b jets from SUSY decay is difficult. many QCD jets

  22. Reconstructing top from gluino decays • t a bW a bjj • N(jet) a7 typically. Many BG to W a jj • Background to t abWabjjis estimated from events in the sideband mjj<mW-15GeV mjj>mW+15 GeV. • Reconstructed top quarks are used to study tb distribution .

  23. Difference between two body and three body Branching ratio is biggest for tb final state. SPS1a: edge with DMtb ~4GeV for 100fb-1 SPS2 :(focus points M=300GeV), distribution may reflect But cross section is small…. (from the plots in Hisano, Kawagoe, Nojiri PRD68.035007) 1000 fb-1 but cut is not optimized

  24. Conclusions • LHC starts soon ! (2007, I hope!) • SUSY is polarized. m(jl) distribution is easy to study. Want more example. Jet charge tagging???? • New “full reconstruction” technique. It works even for small statistics. • Note: If event contains many neutrinos, the method cannot be applied. Go back to the end points? • How to combine end points and “full reconstructions” • We need more thoughts and works. “Crazy theorists” are especially welcome.

  25. And more .. Interplay between LC andLHC

  26. LHC: gluino and two sbottom masses For the wino like second –lightest neutralino If WEAK SUSY parameters are known precisely enough, decay pattern of sbottom may be understood as the function of q. Hisano, Kawagoe, Nojiri (for LHC/LC)

  27. Precise SUSY with LHC/LC • LC can change “silver” to “gold” • Interaction measurements • Checking universality O(1)% O(10%) for GUT scale scalar masses. • Need more precise estimation of running from GUT to weak scale • Fix low energy parameters for DM, Higgs, B, LFV. Ex. O(1%) thermal relic density

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