Status of dark matter searches at colliders Sarah Alam Malik Imperial College London
LHC 2011 2012 2015 2016 Energy 7 TeV 8 TeV 13 TeV 13 TeV Integrated 5 fb -1 20 fb -1 ~4 fb -1 40 fb -1 luminosity ✦ The 2016 proton-proton physics run has ended (26th October). ✦ The final integrated luminosity ~40 fb -1 in ATLAS and CMS ✦ The target for the whole year was 25 fb -1 ! 2
LHC ✦ Mean # of pp collisions in 2015: ~14 ✦ Reached peak luminosity of ~ 1.4x10 34 cm -2 s -1 - 40% above design luminosity ✦ Mean # of pp collisions in 2016: ~24 3
LHC pp run pp run • Expect ~40-50 fb -1 /year in 2017 and 2018 - total of ~ 130 fb -1 by end of 2018 Thanks to efforts of accelerator division, LHC performing above expectation 4
Dark Matter at LHC From Tim Tait 5
Dark Matter at LHC Tim Tait We don’t know what nature has in store for us, cover broadest range of scenarios More complete - SUSY (top down) UV complete models, e.g SUSY Simplified models, e.g Higgs portal, Z’ Effective field theories Less complete (bottom up) 6
Signatures for dark matter searches: Mono-X 7
Monojet/Mono-V search Vector mediated DM production Scalar mediated DM production 8
Monojet/Mono-V search One of the highest MET events in the analysis 9
Missing transverse energy ✦ At the heart of all DM searches at LHC ✦ Challenging quantity to measure ✦ Sensitive to mis-measurements, detector effects, backgrounds ✦ Numerous algorithms developed to deal with anomalous noise producing fake MET and leading to high tail in MET ✦ After cleaning, simulation describes the data well 10
Monojet/Mono-V search CMS EXO-16-037 11
Monojet/Mono-V search CMS EXO-16-037 SM DM M med g 𝝍 g q vector/axial-vector SM DM Excluding mediator mass of upto 2 TeV and DM mass up to 700 GeV 12
Mono-photon search CMS EXO-16-039 Excluding mediator mass of upto 800 GeV and DM mass up to 300 GeV 13
Mono-Z search CMS EXO-16-038 Signature : Z(ll) + MET Excluding mediator mass of upto 600 GeV and DM mass up to 200 GeV 14
Monotop monotop production via (a) neutral flavor-changing current and (b) heavy colored, charged scalar CMS EXO-16-040 Signature: Hadronically decaying W boson from top quark decay + MET 15
ICHEP summary of Mono-X searches Axial-vector mediator Vector mediator CMS CMS Preliminary Preliminary Dark Matter Summary Dark Matter Summary ICHEP 2016 ICHEP 2016 CMS CMS Preliminary Preliminary Dark Matter Summary Dark Matter Summary ICHEP 2016 ICHEP 2016 [GeV] [GeV] Vector mediator, Dirac DM Axial-vector mediator, Dirac DM Observed exclusion 95% CL Observed exclusion 95% CL Observed exclusion 95% CL Observed exclusion 95% CL g = 0.25, g = 1 700 700 g = 0.25, g = 1 q q DM DM DM + j/V DM + j/V [EXO-16-037] [EXO-16-037] 2 DM DM 1 qq qq DM + j/V DM + j/V [EXO-16-037] [EXO-16-037] . 0 ≥ 2 qq qq h DM+j/V m m Ω c 600 600 DM + DM + γ γ [EXO-16-039] [EXO-16-039] DM + DM + γ γ [EXO-16-039] [EXO-16-039] DM + Z DM + Z [EXO-16-038] [EXO-16-038] ll ll 500 500 DM + Z DM + Z [EXO-16-038] [EXO-16-038] DM+j/V DM + t (100% FC) DM + t (100% FC) [EXO-16-040] [EXO-16-040] ll ll DM+top 400 400 300 300 DM+photon 200 200 0.12 2 ≥ h Ω c DM+photon 100 100 DM+Z DM+Z 0 0 0 200 400 600 800 1000 1200 1400 1600 1800 2000 0 200 400 600 800 1000 1200 1400 1600 1800 2000 M [GeV] M [GeV] Med Med 16
ICHEP summary of Mono-X searches ICHEP 2016 ICHEP 2016 ICHEP 2016 ICHEP 2016 35 − 10 33 − ] 10 ] 2 2 [cm [cm CMS Preliminary CMS Preliminary 34 − 10 36 − 10 CMS observed exclusion 90% CL Axial-vector med., Dirac DM Vector med., Dirac DM SD SI − 35 10 g = 0.25, g = 1 g = 0.25, g = 1 CMS DM+j/V q DM σ q σ DM 37 − 10 qq − 36 [EXO-16-037] 10 CMS DM+ γ 38 37 − − 10 10 [EXO-16-039] L 2 o c P i − 38 CMS DM+Z 10 ll 39 − 0 10 6 o c [EXO-16-038] i P 39 − 10 [EXO-16-038] - CMS DM+Z + Super-K τ τ CDMSLite 2015 ll 40 − 10 − 40 DD/ID observed exclusion 90% CL [EXO-16-039] 10 CMS DM+ γ - + τ CRESST-II [EXO-16-038] τ IceCube CMS DM+Z 41 − 41 10 − ll 10 Pico 2L [arXiv:1601.03729] [EXO-16-037] CMS DM+j/V [EXO-16-039] 42 − CMS DM+ γ 10 qq 42 − Pico 60 10 − 43 [arXiv:1510.07754] 10 − 43 + - Super-K τ τ 10 44 − 10 [EXO-16-037] CMS DM+j/V [arXiv:1503.04858] LUX 2015 q q 45 − 10 44 − + - IceCube 10 τ τ PandaX 2016 [arXiv:1601.00653] 46 − 10 − 45 10 47 − 3 10 2 10 10 10 3 2 10 10 10 m [GeV] m [GeV] DM DM 17
ICHEP summary of Mono-X searches CMS Preliminary Dark Matter Summary - ICHEP 2016 DM + jets/V(q q ) EXO-16-037 V -1 g =1, g =0.25 13TeV, 12.9fb AV DM q DM + γ EXO-16-039 V g =1, g =0.25 -1 13TeV, 12.9fb q AV DM spin 1 mediator - + DM + Z(l l ) EXO-16-038 V g =1, g =0.25 -1 13TeV, 12.9fb q AV DM DM + t EXO-16-040 V g =1, a =b =0.25 -1 13TeV, 12.9fb FC FC DM DM + H(bb/ ) γ γ EXO-16-012 m =300GeV; m =100GeV EXO-16-011 0 A DM g =0.8 -1 13TeV, 2.3fb Z' DM + jets/V(q q ) EXO-16-037 S -1 g =g =1 13TeV, 12.9fb spin 0 mediator PS q DM DM + t t EXO-16-005 S / = 2 σ σ -1 g =g =1 13TeV, 2.2fb 0 PS q DM DM exclusions DM + b b /t t mediator B2G-15-007 σ / σ = 5 S 0 exclusions -1 g =g =1 13TeV, 2.2fb / = 30 q σ σ PS DM 0 2 3 4 1 10 10 10 10 Observed limits at 95%CL for considered simplified models V = vector ; AV = axial-vector Maximal excluded mass [GeV] Theory uncertainties not included S = scalar ; PS = pseudoscalar 18
Searches for the mediator Search for narrow resonances decaying into a pair of jets, dijet mass spectrum smoothly falling distribution, no evidence of resonant production EXO-16-032 high mass region low mass region 19
Searches for the mediator EXO-16-032 20
Simplified model exclusion - dijets and mono-X 21
Simplified model exclusion - dijets and mono-X monojet mono photon 22
Simplified model exclusion - dijets and mono-X Search for new resonances in a dijet system accompanied by a photon or jet Initial-State Radiation (ISR) excludes mediator masses starting from 200 GeV R S I + t e j i D 23
Simplified model exclusion - dijets and mono-X Results from the dijet Trigger-object level analysis constrains mediator mass from 425 GeV A L T + t e j i D 24
Simplified model exclusion - dijets and mono-X V e T 8 t e j i D 25
Simplified model exclusion - dijets and mono-X V e T 3 1 t e j i D 26
Higgs to invisible searches CMS-HIG-16-016 Search for Higgs boson production via three channels : - gluon fusion - vector boson fusion - associated vector boson production Combining data from all channels and from 7 TeV, 8 TeV and 13 TeV runs, upper limits on invisible branching fraction of 0.24 at 95% CL 27
Dark Matter at LHC From Tim Tait 28
Limits on Supersymmetry Limits on gluino pairs to 4 tops Limits on stop pairs to 2 tops 29
Limits on Supersymmetry Zoomed limits on ewk-ino production Limits on ewk-ino production 30
Dark Matter interpretation and comparison with DD A lot of work/emphasis on interpretation of dark matter searches within framework of simplified models and their comparison with direct detection experiments ❖ ATLAS-CMS Dark Matter Forum : Nov 2014 - Nov 2015 ❖ LPCC Dark Matter Working Group : Nov 2015 - present Indirect detection Collider experiments Direct detection experiments None of these experiments alone can claim discovery of WIMPs Understanding complementarity will be key in case of discovery 31
Summary ✤ LHC running at unprecedented energy of 13 TeV, so far analysed 1/3 of data collected in 2016 ✤ Searches in place to look for DM producing a variety of signatures within top-down models like SUSY and bottom-up models like EFT and simplified models. ✤ Searches for mediators (dijets) also coming into play and constraining potential mediators coupling SM to DM ✤ Constraints on SM Higgs decays to invisible particles , upper limit on branching fraction 0.24 ✤ Combination of all these searches could play vital role in determining the characteristics of a SM-DM interaction in case of discovery. ✤ Combined ATLAS-CMS-theory effort to benchmark a set of simplified models and accurately elucidate complementarity with direct detection experiments ✤ But so far, no sign of WIMPs. Are we missing something? Are there interesting signatures we’re not looking for? Expecting ~130 fb -1 of data by end of 2018, presents many opportunities. 32
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