Vector Boson Scattering at the Large Hadron Collider

Transcription

1 ector Boson Scattering at the Large Hadron Collider Anja est Universität Bonn 13 November 2014

2 Outline 1 Introduction & motivation 2 ector boson scattering at the LHC 3 Look at physics beyond the SM 4 Summary and outlook Anja est, TU Dresden 2

3 Introduction & motivation The Standard Model of particle physics (SM) the SM is based on 3 fundamental symmetries being origin of interactions between matter particles & mediators of the interactions SU(3) C SU(2) L U(1) Y the Lagrangian density L must be invariant under these symmetries, fundamental principle: local gauge invariance conservation laws main ingredients of the SM: forces: electromagnetism (γ) weak interaction ( ±, Z) strong interaction (g) matter: 6 quarks and 6 leptons in 3 generations ESB: spontaneous electroweak symmetry breaking via Brout-Englert-Higgs mechanism Anja est, TU Dresden 3

4 Standard Model processes Introduction & motivation γ/z ll, lν most frequent and very good understood precisely measured at LEP H, ZZ, γγ and H ττ recently observed at LHC Higgs self couplings not yet seen : limited experimental data accessible in vector boson scattering (BS) ( =, Z, γ) LHC becomes sensitive to BS Anja est, TU Dresden 4

5 Introduction & motivation The Standard Model of particle physics (SM) E theory predicts triple and quartic gauge boson self-interactions γ Z,, Z, γ, Z, γ no neutral gauge boson self-couplings in the SM quartic gauge self-couplings (QGC) contained in: L = g2 4 { [2 + µ µ + (A µ sin θ Z µ cos θ ) 2 ] 2 [ + µ ν + + ν µ + (Aµ sin θ Z µ cos θ )(A ν sin θ Z ν cos θ )] 2} two measurable classes of processes where a QGC vertex contributes: triple gauge boson production, vector boson scattering as jj or exclusive (pp) final states no reaction is ever mediated by a QGC vertex alone (even a gauge-invariant definition of the QGC contribution is not possible!) Anja est, TU Dresden 5

6 Introduction & motivation ector boson scattering and the role of the Higgs boson the heavy vector bosons ± and Z acquire their mass and longitudinal polarization state through spontaneous ESB γ/z the mechanism responsible for ESB must regulate σ( L L L L ) to restore unitarity (= probability conservation) above 1 2 Te cross section attenuated to a linear growth by the quartic gauge boson self-coupling a light SM Higgs boson exactly cancels increase for large s (for H coupling) [ ] A( L L L L ) g2 v 2 s t + + γ/z + + H 0 s2 + t2 s m 2 H t m 2 H + H 0 Anja est, TU Dresden 6

7 Introduction & motivation ector boson scattering and the role of the Higgs boson total cross sections as a function of the m center-of-mass energy: arxiv: σ[nb] σ[nb] 2 σ( ), no Higgs SM without a Higgs boson 1 σ( ) with mh = 120 Ge SM with a 120 Ge Higgs boson ZZ Z + Z ZZ + Z + Z ZZ ZZ s [Ge] s [Ge] unitarity preservation visible only in scattering at large ŝ = m 1 Te scattering is a key process to experimentally probe the SM nature of ESB! Anja est, TU Dresden 7

8 Experimental tests of the E theory at LEP Introduction & motivation SM confirmed at very high precision by the LEP experiments σ (pb) arxiv: LEP triple gauge boson couplings validated by e + e + cross section measurements measured processes with QGC vertices at LEP: significant observation of e + e ννγγ and e + e + γ with very small background OPAL, L3, OPAL, DELPHI consistent with ISR/FSR processes (gauge-invariantly separable from processes containing QGC vertices) YFS/Racoon no Z vertex (Gentle) only ν e exchange (Gentle) s (Ge) e - ν e γ γ no real observation of any process including QGC vertices at LEP (nor at Tevatron) e + ν e Anja est, TU Dresden 8

9 Large Hadron Collider (LHC) at CERN Introduction & motivation pp collisions in 27 km circumference ring centre-of-mass energy: s = 7 Te in 20/2011 s = 8 Te in 2012 s = 13/14 Te from 2015 on Anja est, TU Dresden 9

10 The multi-purpose detectors ATLAS & CMS Introduction & motivation ATLAS CMS candidate Z µµ event with high pileup length 25 cm particles from interaction of interest must be separated from pile-up (multiple interactions per bunch crossing) ATLAS Experiment c 2013 CERN at s = 8 Te: 50 ns bunch spacing and up to 40 interactions/bunch crossing Anja est, TU Dresden

11 ector boson scattering at the LHC ector boson scattering at the LHC Anja est, TU Dresden 11

12 ector boson scattering at the LHC (pp) from exclusive γγ JHEP 07 (2013) 116 first analysis at LHC (CMS, s = 7 Te, L = 5 fb 1 ) pp p ( ) + p ( ) p ( ) e + νµ νp ( ) both very forward-scattered protons escape detection main event selection: 2 high p T isolated opposite charge µe 0 extra tracks from primary vertex m(µ ± e ) > 20 Ge p T (µ ± e ) > 30 Ge (against τ + τ background) 2 events observed 2.2 ± 0.4 signal and 0.84 ± 0.15 background expected γ γ + γ γ + measured cross section: σ = fb ( 1σ) (predicted: σ = 4.0 ± 0.7 fb) upper limit: σ <.6 95% C.L. Anja est, TU Dresden 12

13 ector boson scattering at the LHC ector boson scattering in jj final states protons in LHC serve as source of vector boson beams q q q q H0 H0 ŝ = m Ge (at s pp = 8 Te) signature: diboson + 2 jets ( jj) tagging jets typically with large m jj and well separated in y Anja est, TU Dresden 13

14 jj production process classification ector boson scattering at the LHC electroweak jj production: O(αw) 6 BS diagrams non-bs E diagrams, gauge invariantly q q not separable: separable: q q can be suppressed by BS topology cuts Anja est, TU Dresden 14

15 jj production process classification ector boson scattering at the LHC electroweak jj production: O(αw) 6 BS diagrams non-bs E diagrams, gauge invariantly q q not separable: separable: q q can be suppressed by BS topology cuts strong jj production: O(α 4 wα 2 s) gauge invariantly separable: can be suppressed by BS topology cuts Anja est, TU Dresden 14

16 ector boson scattering at the LHC BS processes (heavy vector bosons only) leading order cross sections (Sherpa) at s = 8 Te: final state sensitive to σ E [fb] σ strong [fb] σ E /σ strong l ± l ± νν jj ± ± :1 l + l νν jj ±, ZZ :35 l + l l ± ν jj ± Z :20 l + l l + l jj ZZ :70* numbers by P. Anger * includes γ, would be also 1:20 1:30 with higher m ll cut (generator cuts: m ll > 4 Ge, p l T > 5 Ge, p j T > 15 Ge) most promising measurable jj final states in terms of BS: same electric charge-sign ( same-sign ) ± ± jj no LO gg or gq initial state strong ± ± jj contributions very small ± Zjj clean channel due to 3-lepton final state g g q ± q ± Anja est, TU Dresden 15

17 ector boson scattering at the LHC Same-sign ± ± jj production at the LHC ± ± jj BS: no s-channel diagrams q q ± q q ± q q ± H0 q q q ± q q ± q ± lowest order: ± ± + 2 jets, there is no SM inclusive ± ± production! event selection according to signature: exactly 2 same-sign leptons, p l T > 25 Ge (e ± e ±, e ± µ ± and µ ± µ ± final states) E miss T > 40 Ge l ± (1) 2 jets with tagging jet (4) p jet T > 30 Ge tagging jet (3) y ν l ± (2) Anja est, TU Dresden ν 16

18 ector boson scattering at the LHC ± ± jj event selection (background) Phys. Rev. Lett. 113, uncertainty on the modeling of low mass Drell-Yan processes m ll > 20 Ge prompt background 3 or more prompt leptons Z/γ and ZZ +jets (Sherpa), t t + /Z (Madgraph+Pythia8), tzj (Sherpa) veto events with any additional e(µ) with p T > 7(6) Ge conversions prompt photon conversion: γ (Alpgen+Herwig/Jimmy, Sherpa) charge mis-id due to bremsstrahlung with conversion (data driven): Z/γ +jets, di-leptonic t t decays, ± +jets Z-veto in ee channel: m ee m Z > Ge other non-prompt background: (data driven) leptons from hadron decays in jets: +jets, semi-leptonic t t decays, dijet events veto events containing b-jets (reduces t t) Anja est, TU Dresden 17

19 ector boson scattering at the LHC ± ± jj production control regions Phys. Rev. Lett. 113, trilepton control region: prompt 1 jet control region: conversions (ee), prompt (µµ) Events/50 Ge ATLAS 20.3 fb, s = 8 Te Tri-lepton CR Data 2012 Syst. Uncertainty ± ± jj ewk+strong Z/γ* ZZ 4l Non-prompt tt+/z Events/ Ge ATLAS 20.3 fb, s = 8 Te 1 jet CR, ee Data 2012 Syst. Uncertainty ± ± jj ewk+strong OS prompt leptons Z/ γ*,zz + γ Other non-prompt tt+/z 20 1 Data/Expected 2 Data/Expected Syst. Uncertainty m jj [Ge] Data/Expected [Ge] m ll Data/Expected Syst. Uncertainty m ll [Ge] Control Region Trilepton 1 jet b-tagged Low m jj e ± e ± exp. 36 ± ± ± 6 76 ± 9 data e ± µ ± exp. 1 ± ± ± ± 16 data µ ± µ ± exp. 60 ± 88 ± ± 7 40 ± 6 data Anja est, TU Dresden 18

20 ector boson scattering at the LHC ± ± jj production Phys. Rev. Lett. 113, E+strong measurement ( inclusive signal region ) m jj > 500 Ge (jets with largest p T ) Events/50 Ge 2 invariant mass of the 2 tagging jets 1 ATLAS 20.3 fb, s = 8 Te Data 2012 Syst. Uncertainty ± ± jj Electroweak ± ± jj Strong Prompt Conversions Other non-prompt E measurement ( BS signal region ) additional cut on y jj > 2.4 Events y jj between the 2 tagging jets ATLAS 20.3 fb, s = 8 Te m jj > 500 Ge Data 2012 Syst. Uncertainty ± ± jj Electroweak ± ± jj Strong Prompt Conversions Other non-prompt 5 Data/Background 5 0 Data/Bkg Bkg Uncertainty (Sig+Bkg)/Bkg m jj [Ge] y jj E and strong ± ± jj from Sherpa, normalized with Powheg Anja est, TU Dresden 19

21 ector boson scattering at the LHC ± ± system in the BS signal region Phys. Rev. Lett. 113, lepton centrality ζ transverse mass of ± ± system Events 25 ATLAS Data 2012 Syst. Uncertainty 20.3 fb, s = 8 Te ± ± jj Electroweak 20 BS SR, ee+eµ+µµ Z/γ*,ZZ,tt+/Z Other non-prompt OS prompt leptons 15 +γ ± ± jj Strong Events/50 Ge ATLAS 20.3 fb, s = 8 Te BS SR, ee+eµ+µµ Data 2012 Syst. Uncertainty ± ± jj Electroweak Z/γ*,ZZ,tt+/Z Other non-prompt +γ OS prompt leptons ± ± jj Strong ζ lepton centrality: miss m T (l,l,e ) [Ge] T ζ = min [ min(η l1, η l2 ) min(η j1, η j2), max(η j1, η j2) max(η l1, η l2 ) ] both leptons between tagging jets (in η): ζ > 0 one or both leptons with larger η than closest jet: ζ < 0 see also PhD thesis by Jan Schumacher, CERN-THESIS-2040 Anja est, TU Dresden 20

22 ector boson scattering at the LHC ± ± jj event yields Phys. Rev. Lett. 113, BS Signal Region e ± e ± e ± µ ± µ ± µ ± Total ± ± jj Electroweak 2.55 ± ± ± ± 1.2 ± ± jj Strong 0.25 ± ± ± ± 0.26 Z/γ,ZZ,t t + /Z 2.2 ± ± ± ± γ 0.7 ± ± ± 1.0 OS prompt leptons 1.39 ± ± ± 0.5 Other non-prompt 0.50 ± ± ± ± 0.7 Total Predicted 7.6 ± ± ± ± 3.5 Data ± ± jj sample composition in BS signal region (all channels combined) Anja est, TU Dresden 21

23 ector boson scattering at the LHC ± ± jj candidate event j2 j1 = 2.9, η j2 = 3.4 jets: pj1 T = 271 Ge, pt = 54 Ge, η µ1 µ2 muons: pt = 180 Ge, pt = 38 Ge, η µ1 = 1.4, η µ2 = 1.3 Anja est, TU Dresden Phys. Rev. Lett. 113, miss = 75 Ge ET 22

24 ector boson scattering at the LHC ± ± jj production cross sections Phys. Rev. Lett. 113, cross sections in inclusive and BS fiducial regions extracted by fitting a likelihood function to the observed data measurement theory prediction PowhegBox+Pythia8 inclusive signal region (E+strong ± ± jj production) cross section [fb] 2.1 ± 0.5(stat) ± 0.3(syst) 1.52 ± 0.11 significance 4.5 σ 3.4 σ BS signal region (E ± ± jj production) cross section [fb] 1.3 ± 0.4(stat) ± 0.2(syst) 0.95 ± 0.06 significance 3.6 σ 2.8 σ interference between E and strong ± ± jj production: 7 ± 4 % (LO, evaluated with Sherpa), included in E signal first evidence of a process dominated by BS and containing a quartic electroweak gauge boson vertex! Anja est, TU Dresden 23

25 ector boson scattering at the LHC ± ± jj production cross sections Phys. Rev. Lett. 113, inclusive phase space (E+strong measurement) BS phase space (E measurement) 1 ATLAS 20.3 fb, s=8 Te 0.8 e ± e ± 2.0 ± 1.5 ± 0.5 [fb] incl SM σ =1.52 ± 0.11 [fb] NLO, POHEG-BOX, CT 1 ATLAS 20.3 fb, s=8 Te 0.8 e ± e ± 0.4 ± 1.0 ±4.0 [fb] SM σ BS =0.95 ± 0.06 [fb] NLO, POHEG-BOX, CT 0.6 e ± µ ± 2.1 ± 0.7 ± 0.3 [fb] 0.6 e ± µ ± 1.3 ± 0.6 ±0.25 [fb] 0.4 µ ± µ ± 2.2 ± 0.9 ± 0.2 [fb] 0.4 µ ± µ ± 1.7 ± 0.8 ± 0.15 [fb] 0.2 Combination 2.1 ± 0.5 ± 0.3 [fb] 0.2 Combination 1.3 ± 0.4 ± 0.2 [fb] incl. [fb] σ BS. σ [fb] Anja est, TU Dresden 24

26 Overview of ATLAS SM cross sections ector boson scattering at the LHC Tiki StandardModelPublicResults Standard Model Production Cross Section Measurements Status: July 2014 σ [pb] µb < pt < 2 Te ATLAS Preliminary Run 1 s = 7, 8 Te < mjj < 5 Te njet 0 35 pb 1 LHC pp s = 7 Te Theory Data fb 1 LHC pp s = 8 Te Theory Data 20.3 fb 1 3 njet 1 njet 0 35 pb 1 2 njet 2 njet 0 njet 1 95% CL upper 1 1 njet 3 njet 2 njet 4 njet 3 njet 4 njet 5 njet 5 njet 4 njet fb fb fb fb 1 95% CL upper limit limit 0.7 fb 1 1 njet 6 njet 7 njet 5 njet 8 njet 6 2 njet 7 njet 7 3 pp Jets Dijets Z t t tt chan + γγ t Z ZZ t tγ γ Zγ t t t tz Zjj H γγ ± jj ts chan R=0.4 R=0.4 Z EK EK total y <3.0 y <3.0 fiducial fiducial total total total total fiducial total total total fiducial fiducial fiducial total total fiducial fiducial fiducial total y <3.0 njet=0 njet=0 Anja est, TU Dresden 25

27 ± ± jj production CMS ector boson scattering at the LHC arxiv: Events / bin E+strong measurement invariant mass of the 2 tagging jets: 5 CMS 19.4 fb (8 Te) Data ± ± jj Other Bkgs. Nonprompt Z (Ge) m jj backgrounds: non-prompt cross section in extended fiducial phase space: leptonic decays of heavy quarks, hadrons misidentified as leptons, electrons from photon conversions in t t decays veto events with any b-jets (reduces t t) Zjj: 3 or more prompt leptons (p l T > Ge, η l < 2.5, p j T > 20 Ge, η j < 5.0, m jj > 300 Ge, η jj > 2.5) veto events with any additional lepton with loose criteria measured: σ = (stat) 1.0 (syst) fb (expected: σ = 5.8 ± 1.2 fb) significance: 2.0 σ (expected: 3.1 σ) Anja est, TU Dresden 26

28 Look at physics beyond the SM Look at physics beyond the SM Anja est, TU Dresden 27

29 Look at physics beyond the SM Look at physics beyond the SM the SM may be considered as a low-energy effective theory of a more complete but unknown theory model independent approach, complementary to direct searches: low energy effects from beyond SM physics can be parametrized by an effective Lagrangian (SM + higher-dimension operators): L eff = L SM + dimension d i c (d) i O(d) d 4 i (valid only, if new physics out of direct LHC reach, s Λ 2 ) new physics in E sector modify gauge boson self-interactions BS could still be strong and differ from SM predictions look at genuine dimension 8 QGC operators with no effect on TGC Λ Anja est, TU Dresden 28

30 Look at physics beyond the SM Look at physics beyond the SM relevant effective aqgc parametrizations (examples): E chiral Lagrangian approach Effective Field Theory description (non-linear representation, dim 4) (linear representation, dim 8), ZZ all α 4, α 5 f S,i /Λ 4, f M,i /Λ 4, f T,i /Λ 4 Appelquist et al. (1980) Eboli et al. (2006), arxiv:hep-ph/ EFT description can be translated in EchL approach and vice versa switch of operator basis, dependent on vertex α 4/5 f S,0/1 conversion arxiv: , Λ 4 arxiv: vertex: α 4 = f S,0 v 4 and α Λ α 5 = f S,1 v 4 Λ 4 8 Anja est, TU Dresden 29

31 Unitarization Look at physics beyond the SM with aqgcs unitarity may be violated even in the presence of a SM Higgs unitarization scheme needed! all unitarization schemes are arbitrary and introduce model dependence! K-matrix method (hizard arxiv: ) scattering amplitude A(s) projected on Argand circle saturation of the amplitude Im[A] non-unitarized SM unitarity bound arxiv: , M. Sekulla Α4 0.1 w unitarisation Standard Model Α4 0.1 w o unitarisation Real I S UB unitarized (K-matrix) s i 2 allows for probing the entire kinematic phase space without being unphysical A K (s) A(s) Re[A] Anja est, TU Dresden 30

32 Look at physics beyond the SM Constraints on aqgcs from ± ± jj Phys. Rev. Lett. 113, exclusion limits on α 4 and α 5 extracted from cross section in BS phase space aqgc samples from hizard+pythia8 with K-matrix unitarization efficiency only weakly dependent on aqgc α ATLAS 20.3 fb, s = 8 Te pp ± ± jj K-matrix unitarization 1D 95% confidence intervals expected: 0. < α 4 < < α 5 < confidence intervals 68% CL 95% CL expected 95% CL Standard Model observed: 0.14 < α 4 < < α 5 < 0.24 (respective other α i = 0) α 4 = scale of new physics: Λ > Ge (rule of thumb: Λ = v/ α i arxiv: ) Anja est, TU Dresden 31

33 Summary and outlook Summary vector boson scattering processes provide a very important test of the electroweak theory and of the dynamics of electroweak symmetry breaking still need to check whether the 125 Ge Higgs unitarizes the BS process completely or if there are other residual effects at higher mass scales first LHC results from ± ± jj production: first evidence for a process dominated by vector boson scattering and containing a quartic electroweak gauge boson vertex Higgs boson glimpsed at work for first time (NewScientist, ) exclusion limits set on aqgc parameters Anja est, TU Dresden 32

34 Outlook Summary and outlook need to explore vector boson scattering at higher energies, complementary to studying Higgs boson properties 13/14 Te: BS in the 500 Ge 2 Te range allows to test the unitarization of the scattering amplitude and to probe the SM nature of ESB extract longitudinal polarization state L look also at ± jj, Zjj, ZZjj and /Zγjj final states,... cross sections at 8 and 13 Te (in BS phase space optimized for 8 Te): final state sensitive to σ E [fb] σ strong [fb] background 8 Te 13 Te 8 Te 13 Te l ± l ± νν jj ± ± ± Z, inst. l + l νν jj ±, ZZ t t and Z+jets l + l l ± ν jj ± Z l production l + l l + l jj ZZ inst. numbers by Ch. Gumpert Anja est, TU Dresden 33

35 Backup

36 Backup ± ± jj: fiducial phase space Phys. Rev. Lett. 113, inclusive signal region exactly 2 leptons with same electric charge e ± e ±, e ± µ ± and µ ± µ ± final states p l T > 25 Ge, η l < 2.5 m ll > 20 Ge R ll > jets reconstructed with the anti-k t algorithm, jet size R = 0.4 E miss T p jet T > 30 Ge, ηjet < 4.5 R jl > 0.3 > 40 Ge invariant mass of the two jets with the largest p T : m jj > 500 Ge BS signal region rapidity separation between the jets with the largest p T : y jj > 2.4 Anja est, TU Dresden 35

37 Backup ± ± jj: kinematic distributions Phys. Rev. Lett. 113, Events/20 Ge ATLAS 20.3 fb, s = 8 Te Incl. SR ee+eµ+µµ Data 2012 Syst. Uncertainty ± ± jj Electroweak ± ± jj Strong Z/γ*,ZZ,tt+/Z OS prompt leptons +γ Other non-prompt Events/25 Ge ATLAS 20.3 fb, s = 8 Te BS SR, ee+eµ+µµ Data 2012 Syst. Uncertainty ± ± jj Electroweak Z/γ*,ZZ,tt+/Z Other non-prompt OS prompt leptons +γ ± ± jj Strong Miss E T [Ge] p (l ) [Ge] T 1 Events ATLAS 70 Data fb, s = 8 Te Syst. Uncertainty ± ± 60 Incl. SR ee+eµ+µµ jj Electroweak ± ± jj Strong 50 Z/γ*,ZZ,tt+/Z OS prompt leptons Other non-prompt 40 +γ 30 Events/ Ge ATLAS 20.3 fb, s = 8 Te BS SR, ee+eµ+µµ Data 2012 Syst. Uncertainty ± ± jj Electroweak Z/γ*,ZZ,tt+/Z Other non-prompt OS prompt leptons +γ ± ± jj Strong N b-jet p (l ) [Ge] T 2 Anja est, TU Dresden 36

38 Backup ± ± jj event yields Phys. Rev. Lett. 113, Inclusive Region e ± e ± e ± µ ± µ ± µ ± Prompt 3.0 ± ± ± 0.6 Conversions 3.2 ± ± 0.8 Other non-prompt 0.61 ± ± ± 0.22 ± ± jj Strong 0.89 ± ± ± 0.23 ± ± jj Electroweak 3.07 ± ± ± 0.5 Total background 6.8 ± ± ± 0.6 Total predicted.7 ± ± ± 1.0 Data Anja est, TU Dresden 37

39 Backup ± ± jj systematic uncertainties Phys. Rev. Lett. 113, Systematic Uncertainties ee/eµ/µµ (%) - BS SR Background Signal Jet uncertainties 13/15/15 Theory ± ± jj-ewk 6.0 Theory Z/γ 4.5/5.4/7.8 Jet uncertainties 5.1 MC statistics 8.9/6.4/8.4 Luminosity 2.8 Fake rate 4.0/7.2/6.8 MC statistics 4.5/2.7/3.7 OS lepton bkg/conversion rate 5.5/4.4/ ET miss reconstruction 1.1 ET miss reconstruction 2.9/3.2/1.4 Lepton reconstruction 1.9/1.0/0.7 Theory + γ 3.1/2.6/ b-tagging efficiency 0.6 Luminosity 1.7/2.1/2.4 Trigger efficiency 0.1/0.3/0.5 Theory ± ± jj-strong 0.9/1.5/2.6 Lepton reconstruction 1.7/1.1/1.1 b-tagging efficiency 0.8/0.9/0.7 Trigger efficiency 0.1/0.2/0.4 Anja est, TU Dresden 38

40 Backup ± ± jj production control regions Phys. Rev. Lett. 113, Events/ Ge t t/b-tag control region: other non-prompt (b-decays) ATLAS 20.3 fb, s = 8 Te b-tag CR, ee+eµ+µµ Data 2012 Syst. Uncertainty ± ± jj ewk+strong OS prompt leptons Other non-prompt tt+/z Z/ γ*,zz + γ Events m jj < 500 Ge control region: mix ATLAS 20.3 fb, s = 8 Te Low m jj CR, ee+eµ+µµ Data 2012 Syst. Uncertainty ± ± jj ewk+strong Z/γ*,ZZ Other non-prompt +γ OS prompt leptons tt+/z Data/Expected 2 1 Data/Expected Syst. Uncertainty p (l ) [Ge] T 1 Data/Expected 2 Data/Expected Syst. Uncertainty 1 y jj y jj Control Region Trilepton 1 jet b-tagged Low m jj e ± e ± exp. 36 ± ± ± 6 76 ± 9 data e ± µ ± exp. 1 ± ± ± ± 16 data µ ± µ ± exp. 60 ± 88 ± ± 7 40 ± 6 data Anja est, TU Dresden 39

41 ] Constraints on aqgcs from ± ± jj Backup exclusion limits on f S,0/1 Λ 4 (α 4 = f S,0 Λ 4 v4 8 and α α 5 = f S,1 Λ 4 v4 8 ): ATLAS CERN-PH-EP , auxiliary material linear translation from K-matrix unitarized α 4/5 CMS arxiv: no unitarization -4 [Te 4 f S,1 / Λ ATLAS 20.3 fb, s = 8 Te pp ± ± jj K-matrix unitarization F S, CMS 19.4 fb (8 Te) Expected 95% CL Observed 95% CL SM confidence intervals 68% CL 95% CL expected 95% CL Standard Model f S,0 / Λ [Te ] F S,0 NB: two different approaches, no conclusion reached yet (CMS yields more stringent limits, however on a physically not meaningful model) Anja est, TU Dresden 40

42 New resonances in electroweak sector Backup arxiv: J = 0 J = 1 J = 2 I = 0 σ 0 (Higgs) ω 0 (γ /Z?) f 0 (Graviton?) I = 1 π ±, π 0 (2HDM?) ρ ±, ρ 0 ( /Z?) a ±, a 0 I = 2 φ ±±, φ ±, φ 0 (Higgs triplett?) t ±±, t ±, t 0 width Γ of the resonances for their decays into longitudinal E gauge bosons dependent on their mass M and coupling g example: vector isovector resonance ρ: Γ g 2 M ρ σ( ), with 500 Ge vector isovector α i parametrize low-mass tail of these resonances unitarization only guaranteed for explicitly included resonance(s) at unique values of the coupling g Z + Z + ZZ ZZ ZZ s [Ge] Anja est, TU Dresden 41

43 ± Zjj: experimental tasks Backup ATLAS-CONF ± Z (+ n jets) can have any number of jets: n = 0, 1, 2, 3,... lowest order: ± Z + 0 jets 3 high p T, isolated leptons 1 opposite-sign lepton pair forming Z within 81 Ge < m ll < 1 Ge residual lepton + E miss T results: forming 94 events observed 277 background events expected (mainly Z+jets & fake leptons) Events / 20 Ge σ total = (stat) (syst) (lumi) pb σ MCFM = 20.3 ± 0.8 pb for ± Z BS measurement: require additional 2 jets s = 8 Te, 13 fb 1 data Z ZZ /Z+γ +jet Z+jet Top ATLAS Preliminary s = 8 Te, L dt = 13 fb [Ge] M Z Anja est, TU Dresden 42

44 Modeling of anomalous quartic gauge couplings Backup E chiral Lagrangian approach (non-linear realization of the gauge symmetry) aqgc operators (dimension 4): L 4 = α 4 (Tr[ µ ν ]) 2 L 5 = α 5 (Tr[ µ µ ]) 2 µ = Σ(D µσ), Σ = e i w v, w: goldstone scalar field triplett aqgc parametrizations: α 4 and α 5 EchL historically motivated as a Higgs-less model, a posteriori modified to include the SM Higgs boson EFT approach (linear realization of gauge symmetry) operators (dimension 8): L S,0 = f S,0 Λ 4 [(D µ Φ) D ν Φ] [(D µ Φ) D ν Φ] L S,1 = f S,1 Λ 4 [(D µ Φ) D µ Φ] [(D ν Φ) D ν Φ] parametrizations: f S,0 Λ and f S,1 4 Λ 4 Anja est, TU Dresden 43

45 Unitarization schemes Backup K-matrix: saturation of amplitude to achieve unitarity form factor: suppression of amplitude to get below unitarity bound Anja est, TU Dresden 44

46 Unitarization Backup with aqgcs unitarity may be violated even in the presence of a SM Higgs (effective parametrization always violates unitarity at some m ) unitarization scheme needed! all unitarization schemes are arbitrary and introduce model dependence! form factors (e.g. in BFNLO arxiv: ) Feigl, Zeppenfeld, 20 F(s) = (1 + ŝ/λ 2 FF) n suppression of amplitude additional arbitrary parameters: exponent n and form factor scale Λ FF weakly motivated, but easy to implement can be generally used for arbitrary anomalous operators needs fine tuning for n = 2 at Λ FF = 2 Te: amplitude suppressed by a factor of 4 Anja est, TU Dresden 45

47 ] Backup Constraints on aqgcs from γγ JHEP 07 (2013) 116 sensitive to γγ vertex additional cut at p T (µ ± e ) > 0 Ge: 0 events left 1D and 2D limits (95% CL) on aqgc parameters a 0 /Λ 2 and a c /Λ 2 : a 0 /Λ 2 < Ge 2 a c /Λ 2 < Ge 2 unitarization with form factor with Λ FF = 500 Ge, n = 2 un-unitarized limits (without form factor): times better, but dominated by ŝ above unitarity 0 improvement wrt. D improvement wrt. LEP Events/30 Ge Data + - Inclusive t t Elastic γγ γγ γγ γγ τ + τ (SM) a 0 ( 2 Λ a0 ( 2 Λ CMS, -4 = 2*, -4 = -2*, + - Drell-Yan τ τ + - Diffractive +jets Inelastic γγ a C = 0, Λ cutoff =500Ge) 2 Λ a C -4 = -8*, Λ cutoff =500Ge) p (eµ) [Ge] s 2 Λ = 7 Te, L = 5.05 fb Anja est, TU Dresden /Λ [Ge ] 46-2 [Ge 2 a C /Λ Standard Model CMS 95% confidence region (Λ cutoff = 500 Ge) a 0 - τ + τ CMS, s = 7 Te, L = 5.05 fb T CMS 1-D limit, 95% confidence region (Λ cutoff = 500 Ge)

48 Kinematic distributions, unitarized Backup comparison of unitarization with K-matrix method (hizard, α 4/5 ) and form factors (BFNLO, f S,0/1 ) at generator level example process: pp qqe + νe + ν φ(leptons) differential cross-section distribution: φ of leptons generator cuts: dσ/d φ[fb] f s0 = f s1 =0 f s0 = f s1 = f s0 = f s1 = f s0 = f s1 = α 4 =0, α 5 =0 α 4 = 0.1, α 5 =0 α 4 = 0.2, α 5 =0 α 4 = 0.4, α 5 =0 A. Melzer φ p l T > Ge, η l < 5 p j T > 20 Ge, ηj < 5 R(jj) > 0.4 m jj > 150 Ge aqgc parameter: f S,0 = f S, α 4 (with f S,0/1 = f S,0/1 Λ 4 Te 4 ) α 5 = 0 Anja est, TU Dresden 47

49 Backup Limits on aqgcs for γγ JHEP 07 (2013) 116 July 2013 LEP L3 limits D0 limits CMS γ limits CMS γ γ limits Anomalous γ γ Quartic Coupling C.L. Channel Limits L s γ [ , 15000] 0.43fb 0.20 Te γ γ [- 430, 430] 9.70fb 1.96 Te 2-2 a 0 /Λ Te γ [- 21, 20] 19.30fb 8.0 Te γ γ [- 4, 4] 5.05fb 7.0 Te γ [ , 26000] 0.43fb 0.20 Te γ γ [- 1500, 1500] 9.70fb 1.96 Te 2-2 a C /Λ Te γ [- 34, 32] 19.30fb 8.0 Te γ γ [- 15, 15] 5.05fb 7.0 Te 4-4 f T,0 /Λ Te γ [- 25, 24] 19.30fb 8.0 Te Anja est, TU Dresden 48 5

50 Effective QGC in BS Backup arxiv: non-linear realization of the gauge symmetry chiral E Lagrangian: L 4 = α 4 g 2 2 L 5 = α 4 g 2 2 { [( + + )( ) + ( + ) 2 ] + 2 c 2 ( + Z)( Z) + 1 w 2c 4 (ZZ) 2} w { ( + ) c 2 ( + )(ZZ) + 1 w 2c 4 (ZZ) 2} w effective parametrization of physics beyond kinematic reach, e.g. resonances at new physics scale Λ = v/ α i wide continuum, narrow particles ZZ ZZZZ AZ AA ZZZA ZZAA ZAAA AAAA O S,0, O S,1 X X O M,0, O M,1,O M,6,O M,7 X X X X X X X O M,2,O M,3, O M,4,O M,5 X X X X X X O T,0,O T,1,O T,2 X X X X X X X X X O T,5,O T,6,O T,7 X X X X X X X X O T,8,O T,9 X X X X X Anja est, TU Dresden 49

51 Prospects for BS at s = 14 Te Backup CERN-ESG-005, ATLAS-PHYS-PUB Te ŝ = m 1 2 Te signal chosen: anomalous BS ZZ tensor singlet resonance f 0 exactly four selected leptons: two opposite sign, same flavor pairs hard benchmark, sensitivity higher for other resonances m resonance coupling width 300 fb fb Ge g = 1 Γ = 2 Ge 2.4σ 7.5σ 1 Te g = 1.75 Γ = 50 Ge 1.7σ 5.5σ 1 Te g = 2.5 Γ = 0 Ge 3.0σ 9.4σ Entries ATLAS Preliminary 1 (Simulation) L dt = 3000 fb SM Non Diboson SM Te Res (g = 1.75) leading m [Te] jj m 4l [Te] Anja est, TU Dresden 50 Entries ATLAS Preliminary 1 (Simulation) L dt = 3000 fb SM Non Diboson SM Te Res (g = 1.75)