SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich SUSY06 Higgs (to bb) final states (including the Hemisphere Separation Algorithm) top final states tau final states New SUSY studies using 3rd generation tagging with the CMS detector New CMS Physics TDR full simulation results on supersymmetry signatures with Filip Moortgat, ETH Zurich

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Neutralino decays in mSUGRA dilepton final state (e, ,  ) through slepton intermediate state Larger tan  -> more taus higgs final state Dominant h 0 decay to bb Large area in parameter space dilepton final state through Z 0 Neutralino 2 decays in mSUGRA:

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Higgs final state 

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Selection At least 4 jets with Et > 30 GeV of which at least 2 b-tagged jets (discriminator > 1.5) MET > 200 GeV Highest jet Pt > 200 GeV Second highest jet Pt > 150 GeV Third highest jet Pt > 50 GeV B-jets in the same hemisphere Smallest  R of b-jet pair (among  R < 1.5) for SUSY  Higgs final states: basic SUSY Higgs  bb optimizing S/B for SUSY optimizing S/B for Higgs Trigger stream = Jet + MET (L1 & HLT) : ~80% efficient HLT thresholds: GeV

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Kinematics : jets at least 4 jets with Et > 30 GeV hard jets … Jets with Et > 30 GeV, GammaJet calibration SUSYSM backgrounds

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Kinematics: MET MET > 200 GeV Missing transverse energy (calculated from the jets):

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich B-tagging working point using Combined Secondary Vertex Algorithm, which combines track and secondary vertex properties into one discriminator : vertex mass, flight path, narrowness, track multiplicity, energy fraction, track impact parameters, … performance in multi-jet chosen working point: b-tagging: 55% c-jets: 12% udsg-jets: 1.6%

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich “Hemisphere” separation Inspired by “thrust/sphericity” methods, but now 2 axes per event due to LSP’s Axis 1 Axis 2 Collect objects in 2 groups with their axis (iterative procedure) Group1 Group2 2 primary sparticles in event they both decay into a cascade separate both cascades will reduce pairing combinatorics!

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich 3 association methods: assign object to the axis for which 1. the scalar product is maximal (|A| = 1) = pure angular test: 2. the hemisphere masses are minimal: 3.the minimal Lund distance: Hemisphere association Axis i Axis j Jet k => 3 seeding methods: 1. 1 st axis: highest momentum object 2 nd axis: object with largest P x ΔR (wrt A1) 2. pair of objects with maximal invariant mass recalculate the axes as sum of objects; iterate till no object changes group

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Hemisphere efficiencies All jetsquark jets gluon jets q from squark q from gluino LM181% 79%87%73% LM577% 74%87%70% LM974%75%69%---76% (using seeding method 2, association method 3) For jets, the probability that the jet is assigned to the “correct” hemisphere = different CMS study points Cleans up invariant mass plots (hq, hqq, lqq, …) significantly Does not work well for leptons (~massless) but there are tricks …

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Angular separation of b-jets SUSYSM within one hemisphere, take only that combination of reconstructed b tagged jets for which the space angle  R is smallest (among those with  R < 1.5) pp b bb q q q h0h0 … hemi1 hemi2

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Cut flow DATA TRIGGER NJET+NBJET MET PTJETCUTS DR+JET PAIRING SIGNAL SUSYBG TTBAR Z+JET < W+JET < Selection efficiency for signal and main backgrounds (in percent), starting after the trigger (L1 + HLT Jet+MET). Trigger efficiency: SUSY : 79% ttbar : 4%

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Mass reconstruction Background  5th order polynomial (with fixed parameters from off peak fit) Signal  gaussian G(m h, 18.2)  = fraction of signal in the plot S cl (1 fb -1 ) = 4.5 Scl = 5 for 1.5 fb -1  = 0.28 ± 0.08 m h = ± 6.6  = 18.2 S cl (1 fb -1 ) = 4.5 M h MC = 116 GeV/c² extract bb width from other measurements (top, ZZ, …) Mass fit:

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Mass reconstruction(2)  ²=0.6  = 0.28 ± 0.04 m h = 118 ± 4.5  = 18.2 S cl (1 fb -1 ) = 7 M h MC = 116 GeV/c²  ²= 1.5  = 0.24 ± 0.02 m h = ± 2.6  = 18.2 S cl (1 fb -1 ) = 11.5

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Systematics Main systematic: Jet energy scale + MET scale (recomputed from corrected Jets): for 1 fb -1 (10 fb -1 ), JES uncertainty goes linear from 15%(10%) at 20 GeV to 5%(3%) at 50 GeV; flat 5 %(3%) above 50 GeV; leads to the following systematic uncertainties: 15 % (7 %) on SUSY event selection ; 17 % (10 %) on t  t background rejection ; Effect on fitted parameters estimated to be : ± 7.5 (5) GeV/c² on m h (and ± 0.04 (0.01) on  ). Tracker misalignment : applying the “short term” misalignment scenario (misalignment of about 100 µm on strips, 20 µm on pixels) => no effect on the position of the invariant mass distribution ; => observed a small drop in number of selected signal events due to the reduced b-tagging efficiency

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Reach in mSUGRA SUSY  Higgs  bb

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Top final states 2nd CMS study: inclusive top + MET signature for SUSY goal: examine low mass SUSY observability target stop and sbottom : often they are light; a lot of top quarks are generated in their decays different backgrounds than the inclusive jet + MET search use CMS test point LM1 where gluino cross section is high (35 pb)

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Working point LM1 LM1 parameters: M 1/2 = 250, M 0 = 60, tan  = 10, sign(  ) = +

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Selection summary

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Kinematic fit (2C) The purpose of this analysis is not to measure the top mass  top mass is used with W mass as the 2 constraints to find the best jet combination. => To reject non-SUSY backgrounds (W+X) => To reject SUSY combinatorial backgrounds Only energy of Jets is smeared in the detector ( checked that directional errors have a small effect.) Last 2 terms: take into account the width of the particles. (Breit-Wigner approximated by Gaussian.) m W and m Top computed from jets. The third jet is a b-jet.

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Kinematic Fit Probability cut here Peak at low probability ( = high  2 ) even for ttbar is due to hadronisation/fragmentation and jetfinding

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Selection (2): kinematic fit

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Reach

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Di-tau final states LM2 Point m 0 = 185 GeV m 1/2 = 350 GeV tan β = 35 A 0 = 0; μ > 0 Always one very soft tau per event 3rd CMS study: inclusive di-tau + MET signature for SUSY For moderate and high values of tan , taus are dominating the di-lepton modes In the following we consider only hardonic tau decays (1- or 3-prong)

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Tau-tagging Need to get tau-jet at energy as low as possible  E t Jet > 5 GeV Need to get as much as possible of visible  energy:   R<0.6 Tau reco. based on standard Tau reco. algo. with regional tracking signal cone  R(lead-track,track)<0.1 and  R(lead-track,Jet)< or 3 tracks in signal cone, No track in isolation cone (smallest fake tau rate) with Pt>1GeV (all tau candidates) & with Pt>0.1 (0.2) Pt leadtrack for single track candidate with Et>60GeV (Et<60GeV) Charge assigned by taking sum of track charge Lead track Pt>5GeV Lead track transverse I.P.<0.7mm  Gives purity of 64% and efficiencies of 17% (E t 60GeV)

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Selection Jets obtained with Iterative Cone  R<0.5 + GammaJet calibration

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Selection: results

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Reach

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Conclusions Several full simulation studies using 3rd generation tagging in CMS have been completed in the framework of the Physics TDR (out soon): Higgs + MET: b-tagging & hemisphere separation significant mSUGRA reach for 10 fb -1 (could be Higgs discovery channel) top + MET: kinematic fit for reconstructing hadronic tops mSUGRA reach for 10 fb -1 upto m 1/2 ~ 500 GeV di-taus + MET: dedicated reconstruction for soft taus mSUGRA reach for 10 fb -1 upto m 1/2 ~ 500 GeV

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich References/Acknowledgements SUSY with h  bb final states: F.M., A. Romeyer, P. Olbrechts, L. Pape (CMS Note 2006/090) Hemisphere separation algorithm: F.M., L. Pape SUSY with top final states: S. Paktinat, L.Pape, M. Spiropulu (CMS Note 2006/102) SUSY with tau final states: D. Mangeol, L. Houchu, U. Goerlach (CMS Note 2006/096) Many thanks to the CMS Thesis Award Committee for the financial support.

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Inclusive reach for 10 fb -1

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Extra

SUSY06, UC Irvine, June 2006Filip Moortgat, ETH Zurich Laser pointers, batteries & naturalness How to put batteries in a laser pointer? (in a “natural” way) simplified toy model : remember batteries have a + and a - side (for weak electro potential) open your pen (turn upper part) & look inside you see one electrical contact in the middle no contact on the other side in the middle => need to take one contact from the side batteries are + on top AND at the side !!!! so - side needs to touch the inner electrical contact  there is only one solution (= ok with naturalness) i.e. + sign up.