Searches for New Physics

Transcription

1 Searches for New Physics (Non-SUSY) Gustaaf Brooijmans For the ATLAS, CDF and CMS Collaborations Rencontres du Vietnam 013, ICISE Inaugural Conference 1

2 Outline There is a Higgs! Are we done? New Physics close to top quarks Vector-like quarks coupling to 3 rd generation New Physics close to W, Z bosons Z, W, ρtc, GRS,... Vector-like quarks coupling to 1 st & nd generations Excited quarks for benchmarks Dark Matter Very weakly coupled

3 New Physics? Could this be it? 3

4 New Physics? Standard Model is a theory of interactions 4

5 New Physics? Where do fermion properties come from? Standard Model is a theory of interactions 5

6 Furthermore Clear structure in fermionic sector unexplained Evidence of (a) selective principle(s) (why are there e.g. no neutral colored fermions?) Proton stability, running of couplings suggestive of at least one other scale relevant to SM particles, ~ 15(?) GeV (Neutrino masses and see-saw for another?) 6

7 Higgs Mass Higgs acquires mass from coupling to W s, fermions, and itself! These mass terms are quadratically divergent Drive Higgs mass to limit of validity of the theory We expect the Higgs mass to be close to the scale where new physics comes in... 7

8 Higgs Mass Candidate #1! 8

9 Singlets, Doublets,... Chiral 4th generation ~excluded Vector-like top partners less constrained... Opens up decay modes Top partner partners: T5/3 B Y-4/3... Rich set of signatures Lots of 3rd generation 9

10 Charge 5/3 Same-sign dileptons! g g BR (pb) σ g T 5/3 T 5/3 CMS-PAS-BG-01 W + W l + ν t t W + W q l + ν b b q q q CMS Preliminary 19.6 fb at s = 8 TeV Observed Limit Expected Limit Expected Limit ± 1σ Expected Limit ± σ Signal Cross-Section M T53 (GeV) Events Events CMS Preliminary 19.6 fb at s = 8 TeV ee+eµ+µµ Data ZZ ± W W ± WWW ttw ttww ttz WZ Charge MisID Non-prompt T53 (600 GeV) Leading lepton p [GeV/c] T CMS Preliminary 19.6 fb at s = 8 TeV ee+eµ+µµ Data ZZ ± W W ± WWW ttw ttww ttz WZ Charge MisID Non-prompt T53 (600 GeV) [GeV] (HT everything but MET) H T j, but before final cuts (on Ncon, HT)

11 W s Can Be Light T Wb with m T ~600 GeV W will be boosted, and if decays hadronically single jet ATLAS-CONF Dijet W Monojet W W-jet 11

12 Wb versus Ht T Wb yields the same final state as t Wb Need good discriminant, e.g. reconstruct T mass ATLAS-CONF l+jets T Wb 1

13 Wb versus Ht T Wb yields the same final state as t Wb Need good discriminant, e.g. reconstruct T mass T Ht: thx, so WbbbX (with X producing 1 b) ATLAS-CONF l+jets ATLAS-CONF l+jets T Wb T Ht (HT everything) 13

14 Wb versus Ht T Wb yields the same final state as t Wb Need good discriminant, e.g. reconstruct T mass T Ht: thx, so WbbbX (with X producing 1 b) ATLAS-CONF l+jets T Wb 14

15 Wb versus Ht T Wb yields the same final state as t Wb Need good discriminant, e.g. reconstruct T mass T Ht: thx, so WbbbX (with X producing 1 b) ATLAS-CONF T Ht 15

16 Closing the Triangle: Zt Opportunity to be more inclusive: Z + b-jets also produced by B Zb Require b-tags (1-tag control region), a high-p T Z (ee or μμ), large H T (jets) ATLAS-CONF

17 All Together Now: T 17

18 All Together Now: B 18

19 Fully Inclusive T Wb, Zt, Ht all produce b-quarks and W s Require at least one leptonic W decay Single lepton: count number of W-jets and top-jets, use BDTs Multilepton: OS (on- and off-z) and SS dilepton, trilepton categories (all with b-tag) Require high H T (jets), ST, (min(mlb)); use counting experiments Events/5 GeV 4 3 CMS preliminary s = 8 TeV 19.6 fb data Drell Yan single top tt CMS-PAS-BG-015 uncertainty OS dileptons T T (800 GeV) 0 (ST everything) Pull 1 min(m ) [GeV] lb min(m ) [GeV] lb 19

20 Result CMS-PAS-BG-015 Lowest point: 687 GeV 0

21 No Top/Bottom Signal? Candidate #! 1

22 No Top/Bottom Signal? New resonances related to W/Z frequent BSM feature Parity restoration (if mass is EWK-scale...) Sign of extra dimensions Vector-like quarks that also couple to 1 st and nd generations Or just a hint of compositeness/excitations AdS 5 G Planck brane SM brane (W or Z-like) x 5 Drawing by G. Landsberg (qv, V = γ,w,z,g) (Decays with W and/or Z)

23 Di-Tau Resonances Hadronically decaying taus particularly challenging Basically few-π jets Use BDT-based τ-identification Few-π QCD jets less frequent at high p T Require high p T candidates (150 and 50 GeV) ATLAS-CONF Dielectron and dimuon: limit at.8 TeV 3

24 Technicolor-Inspired Strongly-coupled EWSB offers a nice solution to the hierarchy problem Difficult to generate fermion masses and satisfy precision EWK constraints... (Pseudo-)scalar composites but also vectors, strongly coupled to W, Z CDF evidence in ρ TC WπTC (i.e. Wjj) now a thing of the past: Separate quark and gluon jet energy scale Refined multijet estimate in ejj CDF Public Note 4

25 Still an interesting scenario however, in a difficult final state Understanding W+jets and Z+jets is crucial to many topics! Sensitivity (to new physics) at ~pb level Incl. Wjj pt (W) > 50GeV central jets ATLAS-CONF

26 Decays to WZ Fully leptonic mode very clean CMS-PAS-EXO-05 W'WZ coupling 1 CMS Preliminary 01 Obs. 95% C.L. Exp. 95% C.L. Exp. ± 1σ Exp. ± σ SSM W'WZ coupling s = 8 TeV L dt = 19.6 fb M(W') (GeV) 6

27 Less Targeted At hadron colliders, leptons are gold Don t really need a model to optimize trilepton search Dilepton tt CR 3e/μ on-z SR ATLAS-CONF

28 Less Targeted At hadron colliders, leptons are gold Don t really need a model to optimize trilepton search Dilepton tt CR 3e/μ on-z SR ATLAS-CONF Fiducial limits (σvis) given, and prescription to evaluate limits for your favorite model 8

29 Hadronic W, Z Looking at hadronic decays allows inclusive search for vector-like quarks, excited quarks, diboson resonances in dijet channel W s and Z s can be light... Tag using jet mass Events CMS-PAS-EXO-04 q* (1.5 TeV) -> qw ( 406) Pythia Z* q* (1.5 TeV) -> qz ( 1170) Pythia Z* (1.5 TeV) -> WW ( 38600) Herwig++ G RS (1.5 TeV) -> ZZ ( 78500) Herwig++ G RS W' ( 1.5 TeV ) -> WZ ( 580) Pythia Z* CMS Preliminary(19.8 fb ) s = 8 TeV CA pruned R=0.8 Untagged data QCD Pythia Z* QCD Herwig Jet Mass (GeV) ) Events / (5 GeV/c CMS Preliminary, _ Proof of principle: W and top jets in tt events! s = 8 TeV, 19.6 fb DATA m W MC m W = 84.3 ± 0.3 GeV/c = 83.7 ± 0. GeV/c Data tt W+Jets Non-W MJ Z+jets Single Top Data fit MC fit Hadronic W Jet Mass (GeV/c ) ) Events / ( GeV/c CMS Preliminary, s = 8 TeV, 19.6 fb CMS-PAS-BG-005 Data Top Candidate Jet Mass (GeV/c tt W+Jets Z+Jets Single Top ) 9

30 Hadronic W, Z Overview: Jet-Algorithms Looking at hadronic decays allows inclusive search for vector-like quarks, excited quarks, diboson resonances in dijet channel W s and Z s can be light... Tag using jet mass, structure: is energy distribution isotropic or not? cone-type ma ene insi η Decompose cluster-type clus nea neig 30

31 Hadronic W, Z Looking at hadronic decays allows inclusive search for vector-like quarks, excited quarks, diboson resonances in dijet channel W s and Z s can be light... Tag using jet mass, structure: is energy distribution isotropic or not? Events Untagged data QCD Pythia Z* QCD Herwig++ q* (1.5 TeV) -> qw ( 406) Pythia Z* q* (1.5 TeV) -> qz ( 1170) Pythia Z* G RS (1.5 TeV) -> WW ( 38600) Herwig++ G RS (1.5 TeV) -> ZZ ( 78500) Herwig++ W' ( 1.5 TeV ) -> WZ ( 580) Pythia Z* CMS Preliminary (19.8 fb ) s = 8 TeV CA R=0.8 CMS-PAS-EXO Jet τ 1 31

32 Hadronic W, Z Looking at hadronic decays allows inclusive search for Events vector-like quarks, excited quarks, diboson resonances in dijet channel W s and Z s can be light... Tag using jet mass, structure: is energy distribution isotropic or not? Untagged data QCD Pythia Z* QCD Herwig++ q* (1.5 TeV) -> qw ( 406) Pythia Z* q* (1.5 TeV) -> qz ( 1170) Pythia Z* G RS (1.5 TeV) -> WW ( 38600) Herwig++ G RS (1.5 TeV) -> ZZ ( 78500) Herwig++ W' ( 1.5 TeV ) -> WZ ( 580) Pythia Z* CMS Preliminary (19.8 fb ) s = 8 TeV CA R=0.8 CMS-PAS-EXO Jet τ 1 Proof of principle: top-jets in tt events! _ 3

33 Hadronic W, Z Looking at hadronic decays allows inclusive search for vector-like quarks, excited quarks, diboson resonances in dijet channel W s and Z s can be light... Tag using jet mass, structure: is energy distribution isotropic or not? Proof of principle: top-jets in tt events! _ 33

34 m = 85.1 GeV m = 97.8 GeV CMS-PAS-EXO-04 34

35 W, Z tagging based on jet mass (70 < m < 0 GeV) τ1 to define medium (0.5 < τ1 < 0.75) and high purity (< 0.5) Two high purity tags for WW, WZ, ZZ resonances CMS-PAS-EXO-04 CMS Preliminary, 19.8 fb, s = 8TeV dσ/dm (pb/gev) σ Data Data-Fit High Purity Double W/Z-tag data Fit G RS ->WW G RS ->WW (1.5 TeV) CMS Preliminary (19.8 fb ) s = 8 TeV η <.5, Δη < 1.3 CA R= Dijet Mass (GeV) BR(X WW) (pb) σ Observed Expected ± 1 σ Expected ± σ Expected G RS WW Resonance mass (TeV) 35

36 W, Z tagging based on jet mass (70 < m < 0 GeV) τ1 to define medium (0.5 < τ1 < 0.75) and high purity (< 0.5) One high purity tag for qw, qz resonances CMS-PAS-EXO-04 CMS Preliminary, 19.8 fb, s = 8TeV dσ/dm (pb/gev) High Purity Single W/Z-tag data Fit q* -> qw CMS Preliminary (19.8 fb ) s = 8 TeV η <.5, Δη < 1.3 CA R=0.8 q* -> qw (3.0 TeV) BR(X qz) (pb) σ 1 - Observed Expected ± 1 σ Expected ± σ Expected q* qz σ Data Data-Fit Dijet Mass (GeV) Resonance mass (TeV) 36

37 Decays to Photons 1.31 TeV 1.5 TeV ATLAS-CONF

38 Decays to Photons 1.31 TeV 1.5 TeV ATLAS-CONF Compare with dijet: ATLAS-CONF

39 Dark Matter? Electroweak-scale WIMPs fit the data well Could be very difficult to see Only particles within reach? Tiny mass splittings? Use ISR W-ISR can be dominant if ξ = 39

40 W Decays Events / 1 GeV miss CMS Preliminary e + E T L dt = 0 fb s = 8 TeV 7 Mχ = 300 GeV Λ = 00 GeV W-> l ν QCD 6 Spin Independent DM ξ = +1 t t + single top γ + jets 5 DM ξ = 0 DM ξ = DY data M T Diboson syst uncer. (GeV) Leptonic Λ (GeV) CMS Preliminary 01 0 fb Spin Independent electron + muon ξ = Limit in 95 C.L. Observed limit Expected CL limit Expected CL ± 1 σ Expected CL ± σ Λ=M χ /(π) Λ=M χ 1 CMS-PAS-EXO3-004 s = 8 TeV M χ (GeV) 3 Hadronic ATLAS-CONF

41 Very Weakly Decaying Suppose new particles get produced, but high potential barrier for decays Hidden valley, SUSY with small RPV, split SUSY, etc. Long lifetimes But could lead to decays to jets! CMS-PAS-EXO cm from primary 41

42 Build likelihood from vertex and track-cluster properties dijets / bin Data QCD H(00) X(350) cτ=35cm H(400) X(150) cτ=40cm H(00) X(50) cτ=0cm CMS Preliminary L dt = 17 pb, s = 8 TeV L xy < 0 cm(low) > 0 cm(high) prompt tracks apple 1 apple 1 prompt energy fraction < 0.15 < 0.09 vertex/cluster disc. > 0.9 > 0.8 expected background 1.60 ± 0.6(stat.) ± 0.51(syst.) 1.14 ± 0.15(stat.) ± 0.5(syst.) observed 1 1 Table 1: Predicted background and the number of observed candidates for optimised selections. Data/QCD Vertex Track Multiplicity CMS-PAS-EXO-038 dijets / bin 6 Data QCD H(00) X(350) cτ=35cm H(400) X(150) cτ=40cm H(00) X(50) cτ=0cm CMS Preliminary L dt = 17 pb, s = 8 TeV [pb] (95% CL) σ B - CMS Preliminary L dt = 18.6 fb, m H = 00 GeV m X = 150 GeV Obs. Limit Exp. Limit Exp. ± 1σ Exp. ± σ s = 8 TeV Data/QCD Cluster RMS cτ [cm] 4

43 Conclusions Cannot do justice to all the ATLAS and CMS results Only most recent shown, more at Probing O(700 GeV) for vector-like top partners O(1.5- TeV) for EWK produced resonances, O(3-4 TeV) quark excitations 43

44 Conclusions Cannot do justice to all the ATLAS and CMS results Only most recent shown, more at Probing O(700 GeV) for vector-like top partners O(1.5- TeV) for EWK produced resonances, O(3-4 TeV) quark excitations Pushes naturalness already... E (finetuning ) signal at s = 14 TeV? 44

45 45

46 _ tt Resonances Two regimes: Resolved : all decay products individually identifiable using standard reconstruction tools (R=0.4 or 0.5 jets) Boosted : Switch to larger R jets to increase efficiency Study jet substructure ATLAS-COM-CONF

47 Lepton+Jets event yield data / bkg 3 W lν 1 CMS Preliminary, 19.6 fb, s = 8 TeV tt others Z' 1.0 TeV/c (1%) Z'.0 TeV/c (1%) Z' 3.0 TeV/c (1%) Uncertainty CMS Data 01 µ+jets, N 1 b-tag [GeV/c ] Boosted M tt x B [pb] Upper Limit σ Z' 1 - CMS, L = 19.6 fb, Expected (95% CL) Observed (95% CL) Z' 1.% width Expected ± 1 s.d CMS-PAS-BG-006 s = 8 TeV Z' with 1.% Decay Width Expected ± s.d. M tt [TeV] Boosted+Resolved ATLAS-COM-CONF

48 All-Hadronic Tough multijet background... Even with advanced substructure tools Nevertheless, not far behind... ) Events / (50 GeV/c 3 Data Non-Top Multijet SM tt 1 CMS Preliminary, s = 8 TeV, 19.6 fb 1 TeV RS KK gluon TeV RS KK gluon 3 TeV RS KK gluon σ(pp Z' tt) (pb) 95% CL Limit on CMS Preliminary, 1 - s = 8 TeV, 19.6 fb 1% Width Z' Expected Limit Observed Limit ± 1 σ ± σ Topcolor Z' 1.3, 1% Width Topcolor Z' 1.3, 1.% Width (Harris, et. al.) tt Invariant Mass (GeV/c ) Z' Mass (GeV/c ) 48

49 ) χ-nucleon σ (cm CMS preliminary 01 0 fb Observed limit Expected limit Expected ± 1 σ Expected ± σ Limit in 90 C.L. Spin Dependent electron + muon 1 ξ = +1 Dark Matter Bonus s = 8 TeV CMS monojet Super-K W W + - IceCube W W SIMPLE 01 M χ (GeV) 3 ) χ-nucleon σ (cm CMS preliminary 01 0 fb Observed limit Expected limit Expected ± 1 σ Expected ± σ Limit in 90 C.L. Spin Independent electron + muon 1 ξ = +1 CMS monojet 01 Xenon 0 01 COUPP 01 SIMPLE 01 CoGeNT 011 CDMSII 011 CDMSII 0 s = 8 TeV M χ (GeV) 3 ) χ-proton σ (cm CMS Preliminary 01 0 fb s = 8 TeV Expected limit for ξ= Spin Independent Expected limit for ξ=0 Expected limit for ξ=+1 Observed limit for ξ= Observed limit for ξ=0 Observed limit for ξ=+1 1 CMS-PAS-EXO3-004 M χ (GeV) 3 ATLAS-CONF