Kai Yi! Univerity of Iowa on behalf of the CMS Collaboration
Outline Motivation! The CMS detector and Jet Recontruction! Monojet + MET! Dijet Reonance! Multijet Reonance! Multijet Tranvere Momentum Sum Shape (Black Hole)! Concluion! 2
Motivation All hadronic final tate i enitive to new phyic from variou model! Strong Dynamic: Jet Reonance! Extra Dimenion: Jet Reonance, Monojet, Black hole! SUSY: Multijet Reonance (RPV)! A channel with many potential dicoverie! Graviton! Dijet reonance! 3
The CMS Detector 4
Jet and MET Recontruction Anti-kt (AK) clutering algorithm with cone ize of 0.5 (AK5) and 0.7 (AK7)! Infrared and collinear afe! Jet type:! Calorimeter Jet:! Recontructed from energy depoit in the EM and HAD calorimeter, grouped in projective calo tower! Particle Flow (PF) Jet:! Ue all detector element to recontruct particle and cluter to jet.! Fat Jet:! Cluter of AK5 PF Jet within radiu of 1.1, optimize dijet reonance reolution by recombining FSR into the two leading jet! Jet energy correction: uing MC truth information and real data! Uncertainty on jet energy cale < 3%! Uncertainty on Jet energy reolution ~%! MET: negative vector um of tranvere momenta of all particle! 5
Monojet + MET (Direct Graviton) Signature: Monojet + MET (graviton)! MET >150 GeV! At mot 2 jet (pt>30 GeV)! p T1 >1 GeV, 1 <2.4! p T2 >30 GeV, 12 <2.0! Data driven background e8ma8on uing μ+jet ample, conitent with QCD MC W/Z + jet Z(νν) + jet No ignificant exce i oberved arxiv:16.4775 [hep-ex]! 6
Limit with 36 pb Oberved and expected limit @95% CL on the ADD parameter M D (TeV/c2) a function of (# of extra-dim)! δ NLO Exp NLO Ob 2 2.41 2.56 3 1.99 2.07 4 1.78 1.86 5 1.68 1.74 6 1.62 1.68 Significant improvement:! =4:! LEP: 0.94 TeV, D0: 0.85 TeV! CDF 1.04 TeV, CMS: 1.86 TeV! =2:! LEP: 1.60 TeV, D0: 0.92 TeV! CDF 1.40 TeV, CMS: 2.56 TeV! Oberved and expected limit @95% CL on the allowed region of unparticle model parameter d U and U! PRD 81 (20) 056003! arxiv:12.3737! 7
Dijet Reonance Search Parton reonance decaying into dijet from variou model! Search for 3 generic type of narrow dijet reonance! qq,qg,gg reonance! Uing fat jet in thi reult! Fat jet how better reolution due to more recovery of FSR! Model X Color J p Γ/(2M) Chan Excited quark q* Triplet ½ + 0.02 qg E 6 Diquark D Triplet 0 + 0.004 qq Axigluon A Octet 1 + 0.05 Coloron C Octet 1-0.05 RS Graviton G Singlet 2 + 0.01 qq, gg Heavy W W Singlet 1-0.01 Heavy Z Z Singlet 1-0.01 String S Mixed Mixed 0.003-0.037 qg,,gg 8
Dijet Reonance with 1 fb Fat PF Jet, <2.5 & <1.3! Data are in good agreement with QCD! Fit to a parameterization, good 2 /d.o.f=27.5/28! No evidence of new phyic! PAS EXO1-015! d!/dm (pb/gev) 1 S (1.8 TeV) " 2 / CMS ndf (1.01 fb ) 27.51 / 28 Prob Fit 0.4907 p0 QCD Pythia 3.238e-05 + CMS ± 1.86e-05 Simulation p1 7.181 ± 0.5794 JES Uncertainty p2 5.847 ± 0.4157 p3 Excited Quark 0.08448 ± 0.08538 String Reonance Preliary -2-3 q* (1.5 TeV) S (2.6 TeV) -4 = 7 TeV # < 2.5 & $# < 1.3 q* (2.3 TeV) Preliary -5 M jj > 838 GeV Fat Jet Significance 2 1 0-2 00 1500 2000 2500 3000 3500 4000 Dijet Ma (GeV) 9
Highet Dijet Ma Event Preliary Preliary Well balanced dijet event!
Dijet Reonance Limit with 1 fb Preliary Preliary Model! Previou CMS Excluded @95% w/ 3 pb (TeV)! Excluded @95% CL w/ 1fb! (TeV)! Expected limit! (TeV)! String Reonance! 0.5-2.5! 1.0 4.00! 3.90! Excited Quark! 0.5.58! 1.0 2.49! 2.67! Axigluon/Coloron! 0.5.52! 1.0 2.47! 2.66! E 6 Diquark! 0.5-0.58,0.97.08,1.45.6! 1.0 3.52! 3.28! W! N/A! 1.0 1.51! 1.42! 11
Multijet Reonance Search for pair produced R-Parity violating Superymmetry gluino (no MET) from 6 jet final tate! Huge combinatorial background beide QCD background! 20 triplet combination from 6 jet! Ue a diagonal cut to remove combinatorial background a well a QCD background:! m jjj < p T (triplet) - (Offet)! Critical cut in multijet reonance earch! 12
Multijet Reonance with 36 pb B (pb) 95% CL Limit! 2 CMS " L dt = 35.1 pb = 7 TeV Oberved Expected ± 1! ± 2!! NLO (Gluino) 200 250 300 350 400 450 500 2 M jjj (GeV/c ) No ignificant exce i oberved! Excluded ma limit of RPV gluino at Bayeian 95% CL i between 200 GeV and 280 GeV! The highet limit to date and the firt limit from pp colliion.! arxiv:17.3084 [hep-ex]! 13
Microcopic Black Hole Search ADD (Arkani-Hamed, Dimopoulo and Dvali) model olution to the hierarchy problem:! M PI2 =8πM D n+2 r n,where M PI i the Planck cale (~ 16 TeV), M D i the true Planck Scale in 4+n dimenion at the electroweak cale! The parton-level cro ection =πr 2, where r (Schwarzchild radiu) i defined a:! Signature: high multiplicity, democratic, and highly iotropic decay with the final-tate particle carrying hundred of GeV of energy.! CMS earch through S T = E T (jet, e,, ) w/ E T >50 GeV, MET i included.! Extract S T hape from N=2,3 ample.! Normalize to event with multiplicity N 3,4,5,6,7,8.! 14
Microcopic Black Hole with 1 fb Event / 0 GeV 6 N = 2 5 4 3 2 1 Data Background Uncertainty = 1.5 TeV, M M D M D M D = 2.0 TeV, M = 2.5 TeV, M BH BH BH 00 1500 2000 2500 3000 3500 4000 Non-QCD tandard model background are negligible! Fit to parameterization! Photon+Jet W+Jet ttbar Z+Jet = 4.5 TeV, n = 6 = 4.0 TeV, n = 4 = 3.5 TeV, n = 2 CMS Preliary = 7 TeV, 1.09 fb S T a) (GeV) Event / 0 GeV 4 3 2 1 N! 3 Data Background Uncertainty = 1.5 TeV, M M D M D M D CMS Preliary = 7 TeV, 1.09 fb = 2.0 TeV, M = 2.5 TeV, M BH BH BH 2000 2500 3000 3500 4000 No ignificant exce i oberved PAS EXO 11 071 = 4.5 TeV, n = 6 = 4.0 TeV, n = 4 = 3.5 TeV, n = 2 S T (GeV) 15 a)
Model Independent Limit with 1 fb )! A (pb) > S T 1 CMS Preliary = 7 TeV, 1.09 fb N # 3 Oberved " 95 Expected " 95 exp. a) )! A (pb) > S T 1 CMS Preliary = 7 TeV, 1.09 fb N # 4 Oberved " 95 Expected " 95 exp. b) )! A (pb) > S T 1 CMS Preliary = 7 TeV, 1.09 fb N # 5 Oberved " 95 Expected " 95 exp. c) T "(S 20, 35 pb T "(S 20, 35 pb T "(S 20, 35 pb -2 2011, 1.09 fb -2 2011, 1.09 fb -2 2011, 1.09 fb 00 2000 3000 4000 5000 (GeV) S T 00 2000 3000 4000 5000 (GeV) S T 00 2000 3000 4000 5000 (GeV) S T )! A (pb) > S T 1 CMS Preliary = 7 TeV, 1.09 fb N # 6 Oberved " 95 Expected " 95 exp. d) )! A (pb) > S T 1 CMS Preliary = 7 TeV, 1.09 fb N # 7 Oberved " 95 Expected " 95 exp. e) )! A (pb) > S T 1 CMS Preliary = 7 TeV, 1.09 fb N # 8 Oberved " 95 Expected " 95 exp. f) T "(S T "(S T "(S -2 2011, 1.09 fb -2 2011, 1.09 fb -2 2011, 1.09 fb 2000 3000 4000 5000 (GeV) S T 2000 3000 4000 5000 (GeV) Significant improvement comparing with 20 data! See backup for model dependent limit! 16 S T 2000 3000 4000 5000 (GeV) S T
Concluion CMS hadronic reonance earche have been preented baed on 20 and 2011 data.! No evidence for new phyic yet.! Data ignificantly contrain many model of new phyic.! 2011 data i quickly uperede 20 reult! 1 fb on tape! A few more fb expected thi year! Ample pace for dicoverie.! Stay tuned! 17
Limit on Microcopic Black Hole (TeV) Excluded M BH 5 4.8 4.6 4.4 CMS Preliary = 7 TeV, 1.09 fb n = 6 n = 4! (pb) 1-2 Theoretical Cro Section M D = 1.6 TeV, M = 1.3 TeV, g = 0.4 M D = 1.3 TeV, M = 1.0 TeV, g = 0.4 M D = 2.1 TeV, M = 1.7 TeV, g = 0.4 String Ball (BlackMax) M D = 1.6 TeV, M = 1.3 TeV, g = 0.4 M D = 1.3 TeV, M = 1.0 TeV, g = 0.4 M D = 2.1 TeV, M = 1.7 TeV, g = 0.4 4.2 BlackMax Non-Rotating Rotating n = 2-3 CMS Preliary = 7 TeV, 1.09 fb 1.5 2 2.5 3 3.5 M D (TeV) 3.5 4 4.5 5 5.5 M The correponding black hole ma limit with different black hole parameter: from ~4.1 to ~5.1 TeV! New limit for the firt time on tring Ball (BLackMax): from 4.1 to 4.5 TeV! tring ball are hypotheized precuror of the emiclaical black hole when the ma of the object i cloe to the Planck cale.! (TeV) 18
Fat jet definition Fat jet optimize dijet reonance reolution by recombining FSR into the two leading jet Fat Jet : cluter of AK5 PF Jet Cluter radiu : R=1.1 Fat Jet algorithm! Select 2 leading AK5 PF jet.! For AK5 PF jet j from 3 to n:! Require:! p T,j > GeV! < 2.5! If Δ R 1j < R Fat and ΔR 2j.! Add j to Fat Jet 1.! If Δ R j2 < R Fat and Δ R 1j.! Add j to Fat Jet 2.! R = 1.1 i bet choice for a ingle earch for qq, qg and gg reonance.! 19
Recombination of Radiation Combined into 1 Fat jet 20
Dijet Centrality Ratio Quantifie the centrality of the dijet angular ditribution at a given dijet ma.! both leading jet are required to lie in the ame range.! Important experimental uncertaintie cancel becaue of the ratio (abolute jet energy cale, luoity).! t-channel cattering for QCD v channel for mot new Phyic model! roughly flat v dijet ma for QCD.! rie v dijet ma for contact interaction.! bump in dijet ma for dijet reonance.! 21
Dijet Centrality Ratio Anti-kt CaloJet with R=0.7! Data i agree with the prediction of the tandard model.! No ign of new phyic.! Set limit on contact interaction cale with modified frequentit approach (CL) method.! Contact interaction cale excluded for <4.0 TeV at 95% CL.! PRL 5, 262001 (20) 22
Background hape for black hole Aume the hape (tail) of QCD ST pectrum i invariant for difference multiplicity bin, we can model background from lower multiplicity, and recale to higher multiplicity.! Fit excluive multiplicity = 2/3 with the following function, in ST [800, 2500] GeV.! Parameterization! 0) P0 (1+x)^P1 / x^(p2 + P3 * log(x))! 1) P0 / (P1 + P2 * x + x^2)^p3! 2) P0 / (P1 + x)^p2! 3) P0 * exp((p3+(p1*log(x)))+(p2*(log(x)^2)))*((p3+p4*log(x)))/x)! 4) P0 *exp(p1*log(x) + P2*x)! Normalization! Recale the fit to incluive multiplicity 3,4,5,6,7,8 in ST [1800, 2000] GeV.! 23