Searches for Heavy Resonances at the LHC Tetiana Berger-Hryn’ova (LAPP, CNRS-IN2P3) For the ATLAS and CMS collaborations Moriond QCD 2014

Higgs Discovery & Searches Following the discovery of a scalar boson Standard Model (SM) is complete (but for an axion) and self-consistent A lot of questions still need answers: – Why is Higgs light? – What is dark matter? – How to accommodate gravity? – Why are there three generations? –…–… – Is there a theory which answers all our questions? We are looking for something – we do not know what – neither where to look – nor if there is any chance of finding it… Does it remind you of something? 2T. Berger-Hryn'ova Moriond QCD 2014

How do we search Approach 1 Pick a Theory Pick a model Look at various production/decay modes of new states! (model-independently) Approach 2 Pick a final state & look (model-independently) Get lucky! It sounds like a quest Go there- I don’t know where, Bring that – I don’t know what 3T. Berger-Hryn'ova Moriond QCD 2014

Look for Signatures! Interesting Models: Extended Gauge Groups Compositeness Wraped Extra Dimentions Technicolor etc … Interesting Signatures: Dibosons  /W/Z+jet(s) Di/Tri-jet Dileptons (ll,  ) etc… Look for bumps on smooth SM backgrounds! 4T. Berger-Hryn'ova Moriond QCD 2014 Focus on selection of results Apologies if your favourite is left out All limits are quoted at either 95% Confidence Level or Credibility Level (CL)

Today’s menu Searches in  +jet final state Dilepton searches Diboson searches Tri-jet resonant searches X  HH  bbbb T. Berger-Hryn'ova Moriond QCD 20145

Searches in  +jet final state Selection CMS(ATLAS): p T j/  >175(125) GeV +  iso; |   |<1.44(1.37), |  j |<3.0(2.8) |  ,j |<2.0(1.6) No significant excess seen. Exclude m(q*)<3.5 95% CL T. Berger-Hryn'ova Moriond QCD Background fit function: ATLAS: PLB 728, 562 (2013)

 +jet limits Limit behaviour quite similar for various models:  (QBH/q*)~83-72/85-80% What happens at high mass? T. Berger-Hryn'ova Moriond QCD Quantum Black Hole (QBH) q*

Effect on limits from Signal Shapes T. Berger-Hryn'ova Moriond QCD Increased fraction of the off-shell production for the signal events (“parton-luminosity tail”) as the kinematic production limit is approached size increases with the resonance width. Noticeable impact of this tail on cross-section limit values when >5-10% of events in the tail  This affects most of the limits (q*, Z’ etc)! Usual signal Breit-Wigner shape Parton distribution functions Parton-luminosity tail

Effect on limits from Signal Shapes T. Berger-Hryn'ova Moriond QCD For thresholds or resonances with suppressed low-mass contributions (Z*) “parton- luminosity tail” effect is not present It is also not present it the resonance shape is input “by hand”, e.g. assuming a Gaussian or Breit-Wigner of certain width, instead of using shape from simulation  QBH Production is a threshold! M D =M TH Mass M D =fundamental scale of quantum gravity M TH =threshold for black hole production

 +jet limits: width effects T. Berger-Hryn'ova Moriond QCD Width assumptions matter at low masses: smaller width = better limits Also parton luminosity tail is larger for wider resonances, which leads to worse limits

Dilepton Resonant Searches Data consistent with SM predictions T. Berger-Hryn'ova Moriond QCD CMS signal shape assumption: Breit-Wigner with Z’  width (  /M=0.5%) convoluted with Gaussian of signal resolution ATLAS signal shape assumption: Monte-Carlo based Z’ SSM shape (with width  /M~3%)

Dilepton Resonant Search Results 95% CL are: M(Z’ SSM ) > 2.96 TeV (CMS) & 2.8 TeV (ATLAS) M(Z’  )>2.60 TeV (CMS) & 2.38 TeV (ATLAS) Those assumptions affect the final results, making limits not comparable directly: effects of parton luminosity tail visible T. Berger-Hryn'ova Moriond QCD

VV & Vq (V=W/Z) Resonant Search Jets Cambridge-Aachen R=0.8, W/Z-tag jet, isolated leptons, kinematic cuts No excess over SM backgrounds is seen  xBR(X  WW)>70 (3) 0.8(2.5) TeV; m(G*  ZZ)>710 GeV for k/M Pl =0.5 Different channels to enhance sensitivity T. Berger-Hryn'ova Moriond QCD See also ATLAS-CONF (ZZ  lljj) & ATLAS-CONF (WW  lll ) k/M Pl =0.1

Search for X  HH  (bb)(bb) 14T. Berger-Hryn'ova Moriond QCD back-to-back boosted doubly btagged di-jet systems 4 b-jets (MV1, eff 70%) anti-kt 0.4 p T >40 GeV,  R(2b) 200 GeV Hadronic ttbar veto Background: multijet (90%); ttbar (<10%); Z+jets No evidence of signal is found CL for k/M Pl = <M(G* RS )<710 GeV <1.6

XX  (3j)(3j) Resonant Search 15 T. Berger-Hryn'ova Moriond QCD 2014 No excess over SM backgrounds is seen. Limits on m(gluino) of 650GeV at 95% CL is set for light flavour jets 835GeV at 95% CL for 2 light and 1 b-jets See also ATLAS-CONF , dijet: CMS PAS EXO 059, ATLAS-CONF

We should not give up! Perspectives/Conclusions Resonant searches are very powerful – Many final states have been explored But no new physics seen in 8 TeV data yet… 16T. Berger-Hryn'ova Moriond QCD 2014 LHC Run 2 will provide us with more luminosity to explore lower couplings & LHC energy increase to higher masses.

We should not give up! Perspectives/Conclusions Resonant searches are very powerful – Many final states have been explored But no new physics seen in 8 TeV data yet… 17T. Berger-Hryn'ova Moriond QCD 2014 LHC Run 2 will provide us with more luminosity to explore lower couplings & LHC energy increase to higher masses. Stay tuned to new exciting results in 2015!

Documentation c/PhysicsResultsEXO c/PhysicsResultsEXO ic/ExoticsPublicResults ic/ExoticsPublicResults T. Berger-Hryn'ova Moriond QCD

Backup slides T. Berger-Hryn'ova Moriond QCD

T. Berger-Hryn'ova Moriond QCD

T. Berger-Hryn'ova Moriond QCD

Dijet Search T. Berger-Hryn'ova Moriond QCD CMS PAS EXO 059, ATLAS-CONF

Z’  hadronic search Z’  hadhad (~42% of the BF) No excess over SM backgrounds seen. Excluded M(Z’ SSM 95%CL 23