SUSY Strong Production Searches @ ATLAS Christopher Young 18th March 2012 Entries / 100 GeV ∫ 1/2 ∫ Events / 200 GeV ATLAS Preliminary Data 2011 ( s =7 TeV) -1 -1 Data 2011 ( s = 7 TeV) 4 L dt = 4.7 fb Number of events / 2 GeV 5 10 10 L dt ~ 4.7 fb Background prediction Standard Model 4 ∫ 10 Data 2011 ( s = 7 TeV) → -1 multijets (data estimate) Multi-jets (inc. t t qq) L dt = 4.7 fb SM Total W+jets 4 ATLAS Preliminary → 10 Alpgen t t ql,ll t t and single top Z+jets → µ τ ν 3 Alpgen W (e, , ) 10 Z+jets t t 4-Jet Analysis 3 → ν ν 10 W+jets Alpgen Z single top 3 µ 10 → τ τ e and combined Diboson Alpgen Z Dibosons multijet m m MSUGRA m =820 m =300 SUSY =2960, =240 2 0 1/2 10 0 1/2 SM+SU(500,570,0,10) 10 2 4-Jet Signal Region before m inc cut 10 2 ≥ eff SM+SU(2500,270,0,10) 8 jets p > 55 GeV T ATLAS Preliminary 10 10 SRA 10 1 1 -1 1 10 -1 10 -2 10 0 2 4 6 8 10 12 14 16 DATA / SM 0 500 1000 1500 2000 2500 3000 2 Data / SM 2.5 DATA / Prediction 2 2 1.5 1.5 1 1 1 0.5 0.5 0 0 0 0 500 1000 1500 2000 2500 3000 0 2 4 6 8 10 12 14 16 400 600 800 1000 1200 1400 1600 miss 1/2 m (incl.) [GeV] E / H [GeV ] m inc [GeV] eff T T eff Entries / 100 GeV Events / 0.1 ∫ 1/2 ∫ Data 2011 ( s =7 TeV) -1 Data 2011 ( s = 7 TeV) ATLAS Preliminary L dt = 4.7 fb Number of events / 2 GeV -1 5 L dt ~ 4.7 fb Standard Model 10 Background prediction ∫ Data 2011 ( s = 7 TeV) 60 -1 multijets (data estimate) L dt = 4.7 fb 2 → 10 Multi-jets (inc. t t qq) W+jets SM Total → 10 4 ATLAS Preliminary Alpgen t t ql,ll Z+jets t t and single top Combined Soft Lepton → µ τ ν Alpgen W (e, , ) Z+jets t t → ν ν W+jets Alpgen Z single top 3 10 → τ τ Diboson Alpgen Z Dibosons multijet SUSY m =2960, m =240 40 Simplified model 0 1/2 SM+SU(500,570,0,10) 2 m ~ =425 m =345 10 g LSP 10 ≥ SM+SU(2500,270,0,10) 7 jets p > 80 GeV Soft Lepton Signal Region T ATLAS Preliminary before E miss / m cut 10 T eff SRE 1 20 1 -1 10 -2 10 0 0 2 4 6 8 10 12 14 16 DATA / SM 0 500 1000 1500 2000 2500 3000 2.5 DATA / Prediction 2 Data / SM 2 2 1.5 1.5 1 1 1 0.5 0.5 0 0 0 0 500 1000 1500 2000 2500 3000 0 2 4 6 8 10 12 14 16 0.1 0.2 0.3 0.4 0.5 1 / 48 0.6 0.7 m (incl.) [GeV] E miss / H [GeV 1/2 ] miss E / m eff T T T eff
SUSY Strong Production Searches @ ATLAS Christopher Young Contents ◮ Very brief introduction ◮ The suite of ATLAS searches for Strongly Produced SUSY ◮ 0-lepton m eff search ( ≥ 2 − 6 jets) (ATLAS-CONF-2012-033) ◮ 0-lepton high jet multiplicity search ( ≥ 6 − 9 jets) (ATLAS-CONF-2012-037) ◮ 1-lepton search ( ≥ 3 − 4 jets) (hard and soft leptons) (ATLAS-CONF-2012-041) - NEW this week! ◮ Conclusions 2 / 48
SUSY Strong Production Searches @ ATLAS Christopher Young Introduction � � � ◮ SUSY strong production is characterised by the pair and associated production of squarks (˜ q ) and gluinos (˜ g ). ◮ These can then decay either directly to the LSP (usually assumed to be the lightest neutralino) or through a series of intermediate SUSY particles. ¯ q q q ¯ ˜ g g ˜ q q ˜ q ˜ q ˜ q W + χ + ˜ 1 χ 0 χ 0 ˜ χ 0 ˜ ˜ 1 1 1 ◮ In the R-Parity conserving models considered the lightest neutralino is assumed to be (collider) stable so passes through the detector undetected. ◮ Signatures therefore involve jets, missing transverse energy ( E miss ) and possibly T leptons (inc. τ s) from cascade decays (and, additionally, possibly photons). ◮ Searches for R-Parity violating SUSY, long lived charged particles and specific searches for gauginos and 3rd generation squarks are covered in separate talks. 3 / 48
SUSY Strong Production Searches @ ATLAS Christopher Young Introduction II ◮ Here I am presenting three ATLAS analyses with the full 2011 dataset which have sensitivity to these models of interest; 1. 0-lepton m eff ( ≥ 2 − 6 jets) (ATLAS-CONF-2012-033) 2. 0-lepton high multiplicity ( ≥ 6 − 9 jets) (ATLAS-CONF-2012-037) 3. 1-lepton ( ≥ 3 − 4 jets) (ATLAS-CONF-2012-041) - NEW this week! ◮ There are many other ATLAS analyses also sensitive to these models that are still in the process of being updated to the full dataset: ◮ Di-photon + E miss (1.07fb − 1 ) arXiv:1111.4116 T ◮ Di-lepton + jets + E miss (1.04fb − 1 ) arXiv:1110.6189 T ◮ ≥ 1 τ + jets + E miss (2.05fb − 1 ) ATLAS-CONF-2012-005 T ◮ ≥ 2 τ s + E miss (2.05fb − 1 ) ATLAS-CONF-2012-002 T ◮ 2 Same Sign leptons + jets + E miss (2.05fb − 1 ) ATLAS-CONF-2012-004 T ◮ ≥ 4 leptons + E miss (2.05fb − 1 ) ATLAS-CONF-2012-001 T ◮ For a full list and more information please see; https://twiki.cern.ch/twiki/bin/view/AtlasPublic/SupersymmetryPublicResults 4 / 48
SUSY Strong Production Searches @ ATLAS Christopher Young ≥ 1 τ and ≥ 2 τ Analysis Results ◮ τ leptons can often be found in the cascade decays. (eg. ˜ τ NLSP) ◮ Dedicated searches have looked at the ≥ 1 τ and ≥ 2 τ final states. ◮ No significant excess was observed and limits were set in a GMSB model. ◮ Below are the signal regions before the final cuts for the ≥ 1 τ (upper) and ≥ 2 τ (lower) analyses and the two exclusion limits. 60 Events / 100 GeV Total SM ATLAS µ 50 GMSB: M =250 TeV, N =3, >0, C =1 multijets Preliminary mess 5 grav ∫ 50 Z + Jets β -1 40 Ldt = 2.05 fb tan W + Jets ATLAS Preliminary top ∼ 30 45 LEP 95% CL ( τ ) s =7 TeV ~ 1 data 2011 LEP 95% CL ( e ) R OPAL 95% CL GMSB(40,30) 20 Theory excl. 40 GMSB(30,20) CL 95% CL limit: s 10 2 leptons (1 fb -1 ) 35 obs. limit exp. limit 0 200 400 600 800 1000 1200 1400 1600 ≥ -1 1 tau (2 fb ) m [GeV] 30 obs. limit eff exp. limit ≥ -1 8 2 taus (2 fb ) Events / 40 GeV 25 obs. limit ATLAS Preliminary exp. limit Data 2011 7 ∫ Standard Model 20 -1 L dt = 2.05 fb s =7 TeV ∼ 6 Top τ W+jets ∼ 1 5 Z+jets χ 0 15 GMSB4030 1 4 CoNLSP 10 3 ~ l 2 R 5 1 10 20 30 40 50 60 70 0 Λ 5 / 48 0 100 200 300 400 500 600 700 [TeV] τ τ m + m [GeV] 1 2 T T
SUSY Strong Production Searches @ ATLAS Christopher Young 0-lepton m eff Analysis 6 / 48
SUSY Strong Production Searches @ ATLAS Christopher Young 0-lepton m eff Analysis ◮ Update of previous published result ( arXiv:1109.6572 ) with re-optimised signal region definitions (including extension to ≥ 5 and ≥ 6 jets), improved background determination and increased integrated luminosity. ◮ Veto events with electons ( p T > 20 GeV | η | < 2 . 47) or muons ( p T > 10 GeV | η | < 2 . 4). ◮ The data is split into different streams by inclusive multiplicity ranging from ≥ 2 to ≥ 6 jets. ◮ This is designed to maintain good sensitivity to a large range of models from those with directly decaying squarks giving ≥ 2 jets in the final state to longer decay chains with many jets in the final state. ◮ The discriminating variable m eff (incl.) is defined as the scalar sum of the E miss T and all the jets in the event with p T > 40 GeV. ◮ Multi-jet processes with no/low real E miss are reduced to a very small level T through cuts on the minimum azimuthal angle between jets and the E miss and T / m eff ( N J ) 1 on the ratio of E miss T ◮ A second 2-jet stream is defined with a tighter cut on E miss / m eff ( N J ) designed T to enhance sensitivity to models with smaller sparticle mass splittings. ◮ In total 11 signal regions are defined. 7 / 48 1When forming this ratio m eff is computed from the leading N jets in the N jet stream.
SUSY Strong Production Searches @ ATLAS Christopher Young 0-lepton m eff Analysis: Signal Region Cuts Channel Requirement A A’ B C D E E miss [GeV] > 160 T p T ( j 1 ) [GeV] > 130 p T ( j 2 ) [GeV] > 60 p T ( j 3 ) [GeV] > – – 60 60 60 60 p T ( j 4 ) [GeV] > – – – 60 60 60 p T ( j 5 ) [GeV] > – – – – 40 40 p T ( j 6 ) [GeV] > – – – – – 40 ∆ φ ( j i , E miss ) > 0.4 ( i = { 1 , 2 , (3) } ) 0.4 ( i = { 1 , 2 , 3 } ), 0.2 ( p T > 40 GeV jets) T E miss / m eff ( Nj ) > 0.3 (2j) 0.4 (2j) 0.25 (3j) 0.25 (4j) 0.2 (5j) 0.15 (6j) T m eff ( incl . ) [GeV] > 1900/1400/– –/1200/– 1900/–/– 1500/1200/900 1500/–/– 1400/1200/900 Cuts used to define each of the channels in the analysis. SRs are defined by the last cut on m eff (incl.). The E miss / m eff cut in any N jet channel uses a value of m eff constructed from only the leading N jets. However, the T final m eff (incl.) selection uses all jets with p T > 40 GeV. The three m eff (incl.) selections listed in the final row 8 / 48 denote the ‘tight’, ‘medium’ and ‘loose’ selections respectively. Not all channels possess all three SRs.
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