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Dark Matter Searches at the LHC

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Dark Matter Searches at the LHC Future Prospects for Particle Physics Albert De Roeck CERN, Geneva, Switzerland Antwerp University Belgium UC-Davis California USA BU, Cairo, Egypt NTU, Singapore Santiago de la Compostela 3rd September 2019 Experiments: CMS (CERN), MoEDAL (CERN), DUNE (FNAL), T2K (Japan), SoLid (Belgium)… + a few other (smaller) experiments + studies for the future.. Outline • Introduction: Experimental Techniques • Results from the Large Hadron Collider -The Higgs Boson -Supersymmetry? Dark Matter?..? • The Future at the LHC Collider/accelerator based view • Next possible Facilities/Challenges • Summary 2 What is the world made of? What holds the world together? Where did we come from? High Energy Physics Experiments First High Energy Physics High Energy Physics Experiments: Experiments since mid 70’s: Beam on fixed target! Colliding beams! Rutherford experiment (1913) Centre of mass energy squared s=2E1m2 Centre of mass energy squared s=4E1E2 …plus secondary beams such as neutrinos… The Rutherford Experiment 1913 Rutherford experiment: Unexpected Backscattering of α-particles: Evidence for the structure of atoms !! H. Geiger (postdoc) and E. Marsden (undergraduate) were the “electronics” of the detector But modern experiments without electronics are (almost) unthinkable!!! Accelerators are Powerful Microscopes Planck constant High energy particle beams h allow us to see small things = p momentum wavelength ~ energy High energy particle beams allow us to produce massive particles The Standard Model gauge x8 In 50 years, we’ve come a long way, but there is still much to learn… Fermions: particles with spin ½ Bosons: particles with integer spin Until 2011 no single fundamental scalar had been observed yet! Do they exist in Nature? Physics case for new High Energy Machines From ~1990’s Understand the mechanism Electroweak Symmetry Breaking Discover physics beyond the Standard Model Reminder: The Standard Model - tells us how but not why 3 flavour families? Mass spectra? Hierarchy? 19 parameters! - needs fine tuning of parameters to level of 10-30 ! - has no connection with gravity - no unification of the forces at high energy Most popular extensions around 2000 - Supersymmetry - Extra space dimensions Many other ideas: More symmetry and gauge bosons, composite Higgs models, L-R symmetry, quark & lepton substructure, Little Higgs models, Technicolor, Hidden Valleys, Vector-like quarks… Higgsless models rather disfavoured these days The Hunt for the Higgs The key question (pre-2012): Where do the masses of Does the Higgs particle exist? elementary particles come from? If so, where is the Higgs? Massless particles move at the speed We do not know the of light -> no atom formation!! mass of the Higgs Boson Scalar field with at least Note: NOT the mass of It could be anywhere protons and neutrons one scalar particle from 114 to ~7009 GeV The LHC Machine and Experiments moedal LHCf totem Seven LHC experiments in operation! ..Proposals for additional “small” experiments to cover more… The Large Hadron Collider = a proton proton collider Also a heavy ion collider 7 TeV + 7 TeV 6.5 TeV + 6.5 TeV (4/3.5 TeV + 4/3.5 TeV) Primary physics targets Origin of mass Nature of Dark Matter Understanding space time Matter versus antimatter Primordial plasma The LHC is a Discovery Machine The LHC can determine the future course of High Energy Physics Reminder: This is what we do! proton proton 13 TeV …40 Million times a second - 24/7 (if we could) Out comes the Higgs & New Physics (…or not) The Compact Muon Solenoid Experiment The CMS Collaboration: >3200 scientists and engineers, >800 students from ~190 Institutions in 44 countries . In total about ~100 000 000 electronic channels Each channel checked 40 000 000 times per second (bunch X rate is 40 MHz) An on-line trigger selects events and reduces the rate from 40MHz to ~ 1kHz Amount of data for just one bunch crossing ~2 000 000 Bytes CMS before closure Can be seen as above during the CERN open door days: 14-15 September… From Collisions to Papers… Pile-up: multiple collisions in one bunch crossing ~ 40! Readout Electronics.. Event Builder and Trigger Electronics 2012: A Milestone in Particle Physics Observation of a Higgs Particle at the LHC, after about 40 years of experimental searches to find it proton proton 2013 The Higgs particle was the last missing particle in the Standard Model and possibly our portal to physics Beyond the Standard Model Most cited LHC paper so far... September 2012 Special Physics Letters B edition CMS week Lisboa with the ATLAS and CMS CMS papers on the Higgs Discovery Also… Elsevier PHYSICS LETTERS B Cited about 9500 times so far… Tuesday 8 October 2013 Francois Englert Peter Higgs Congratulations!!!! 19 Brief Higgs Summary (so far) We know already a lot on this brand New Higgs particle!! Mass = CMS+ATLAS Width Couplings are Spin = 125.09 ±0.21(stat) < 9 MeV within ~10-20% 0+(+) preferred ±0.11(syst) GeV (95%CL) of the SM values over 0-,1,2 We continue to look for anomalies, i.e. unexpected decay modes or couplings, multi-Higgs production, heavier Higgses, charged Higgses… Brief Higgs Summary (so far) Combination of all Higgs production/decay channels at 13 TeV Check overall consistency of the couplings ATLAS-CONF-2018-031 CMS: arXiv:1809.10733 Results in agreement with the Standard Model The Study of the Higgs June 2019 FCC meeting The Future: Studying the Higgs… More LHC Data 2021-2023 LHC upgrade ! 2026-2036 Experiment upgrades!! Other/new machines? -> see later Many questions are still unanswered: What explain a Higgs mass ~ 125 GeV? What explains the particle mass pattern? Connection with Dark Matter? What is the origin of neutrino masses? … Physics Beyond the Standard Model? A Higgs at 125 GeV Precise measurements of the top quark and the Higgs mass arXiv:1403.6535 We also know that: New Physics inevitable? But at which scale/energy? Searches!! N. Arkani-Hamed New Physics? J. Ellis, 2017 007 Reasons for new Physics https://ep-news.web.cern.ch • 001) Within the Standard Model, the electroweak vacuum is unstable against decay to high Higgs field values. • 002) The Standard Model has no candidate for dark matter. • 003) The Cabibbo-Kobayashi-Maskawa (CKM) Model does not explain the origin of the matter in the universe. Where is the anti-matter? • 004) The Standard Model does not have a satisfactory mechanism for generating neutrino masses. • 005) The Standard Model does not explain or stabilize the hierarchy of mass scales in physics. • 006) The Standard Model does not have a satisfactory mechanism for cosmological inflation. • 007) We need a quantum theory of gravity. Beyond the Higgs Boson Supersymmetry: a new symmetry in Nature? Candidate particles for Dark Matter Produce Dark Matter in the lab SUSY particle production at the LHC Picture from Marusa Bradac The SUSY SEARCH Chart So Far… No evidence for SUSY found yet. More than 100 different analyses performed Excluded squark and gluino mass region: Excluded!! EPS19/LP19: Still no significant sign yet of SUSY with full run-2 data (140fb-1) SUSY (as seen from outside HEP…) But we are not November ‘16 reported by The Economist (!?!): giving up yet!!! A lot more analyses are still ongoing. New ideas being tried out Keep the party ready.. http://www.economist.com/news/science-and-technology/21709946-supersymmetry-beautiful-idea-there-still-no-evidence-support-it Dark Matter Searches at the LHC Identifying Dark Mono- object Matter is one of the signature most important questions in physics Is Dark Matter today! a new weakly It is likely a new as yet interacting undetected particle particle??? Can it be produced at the LHC? Comparison with Direct Detection No signal seen in any of the “mono”-signals so far Extend limits by search for the mediator Axial-vector mediator and Vector mediator and Spin-dependent direct limits Spin-independent direct limits 90% CL limits Mono-jet/V & Dijet searches are typically the most sensitive ones New Physics Searches: Limits!! 31 Are we leaving no stone unturned? • The LHC BSM searches are indispensable and should be continued in the new energy regime and with increasing statistics (higher mass, lower couplings) • But if we still do not see more than a 2 sigma at the end of run-3, the HL-LHC will be likely mostly a precision physics machine, searching for subtle deviations • Are we looking at the right place? Time for more effort in thinking of complementary searches? Are we looking at the right place? Leave no stone unturned!! LHCb: Tests of Lepton Universality A few puzzling results from the LHCb experiment… If confirmed, independent checks will become very important. Belle II? ->in a few years form now CMS has installed a special trigger to collect an unbiased b-sample which is active since 2018 -> more than 1010 b-pairs collected during 2018 via parked data stream First LHCb run-2 results did not yet clarify the situation (Moriond 2019) MoEDAL: Monopole and Exotics Detector at the LHC Heavy particles which carry “magnetic charge” Could eg explain charge quantization in the Universe Monopole production Remove the sheets after some running time and inspect for ‘holes’ Monopole Searches: MoEDAL @ 13TeV 2016 data analysis base on 794 kg Aluminium to “stop” the monopoles and search for them with a SQUID precision magnet (4.0fb-1) arXiv:1903.08491 Limits for different monopole charges First monopole search result @LHC at 13 TeV No signal yet. Proposals for New Experiments @LHC MilliQan: searches for CODEX-b: searches for long lived millicharged particles weakly interacting neutral particles MATHUSLA: searches for long lived FASER: searches for long lived weakly interacting neutral particles dark photons-like particles Recent also AL3X (re-use of ALICE for LLP)… The New Wave: Machine Learning M. Pierini et al.
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