Energy Frontier Colliders and Snowmass Process 50 th

Energy Frontier Colliders and Snowmass Process (50 th anniversary of the Standard Model) October 25, 2018 US LHC Users Association Meeting Young-Kee Kim The University of Chicago Dedicated to Burt Richter 1931 -3 -22 ~ 2018 -7 -18 Helen Edwards 1936 -5 -27 ~ 2016 -6 -21 Leon Lederman 1922 -7 -15 ~ 2018 -10 -3

2019 APS April Meeting April 13 – 16, Denver 3 Invited Sessions: Honoring Burt Richter Honoring Helen Edwards Honoring Leon Lederman Burt Richter 1931 -3 -22 ~ 2018 -7 -18 Helen Edwards 1936 -5 -27 ~ 2016 -6 -21 Leon Lederman 1922 -7 -15 ~ 2018 -10 -3

The Standard Model of Particle Physics Most of us have grown up with the Standard Model’s orderly account of the fundamental particles and interactions

50 years ago

“A Model of Leptons” November 1967 Weinberg’s iconic paper “A Model of Leptons” (Core of the Standard Model) # of citations per year !! 400 1 citation / day 300 200 1 citation / 2 days 100 0 1967 2018

Experimental Preludes elementary particles . Particles discovered: Cosmic rays Produced by accelerators Parity (P) violation (1957) CP-violation in Kaon (1964)

Theoretical Preludes Quantum electrodynamics (QED) well established No mature theories of the strong and weak interactions Weak force: Fermi Theory V-A Theory Cabbibo angle The weak force exhibits some common features with QED. It might be mediated by a vector boson (W) analogous to the photon (g). The W would have to be very massive empirically The mathematical symmetry of theory required massless W like g.

Theoretical Preludes Idea of spontaneously broken symmetry (1960) (Higgs mechanism) Demonstration of vector bosons becoming massive without spoiling the fundamental gauge symmetry (1964) Strong interactions in mind (protons, neutrons, pions and r-mesons)

“A Model of Leptons” Applying the idea to leptons (e and n) Massless g (EM interactions); Hypothetical massive W (weak interactions) Unified electromagnetic and weak interactions

Standard Model @ 50: Successes Late 1960 s: Solar neutrino deficit 1968: Direct proof of the quark model (ep scattering experiments revealed the structure of the proton as a bound state of quarks) 1973: Discovery of neutral currents (weak interactions). The first example of a single-electron neutral current nm 2001: Discovery of neutrino oscillation : 1998 2000: Discovery of CP violation in B 1973: 3 generation quark mixing matrix and CP violation in SM (theory)

Standard Model @ 50: Successes c q g nt Tevatron b H QCD was established as theory of the strong interactions

Standard Model @ 50: Successes c q b g nt Tevatron Discovered at energy-frontier colliders H QCD was established as theory of the strong interactions

Particles Discovered at Energy Frontier Colliders hydrogen atom mass Higgs boson Top quark b c Z gluons W t Spin ½ Fermions Spin 0 Boson Spin 1 Bosons

Energy Frontier Colliders 1970 SPEAR (e+e-) PEP (e+e-) PETRA (e+e-) TRISTAN (e+e-) SLC (e+e-) LEP (e+e-) 1980 1990 2000 2010 2020 2030 Discovery of an elementary particle HERA (e+p, e-p) ISR (pp) Spp. S (pp-bar) Tevatron (pp-bar) LHC (pp) ? Now Have also played crucial roles in testing the Standard Model via precision measurements and rare processes

Testing the Standard Model e+e- cross section (pb) Electroweak measurements & theoretical calculations (e+e- colliders) (1974 – 2000) g e g+Z q q + Interference e e e+e- center-of-mass energy (Ge. V) Z q q

Testing the Standard Model _ Tevatron pp collider at 2 Te. V LHC pp collider at 13 Te. V A wide range of measurements: SM predictions have been essentially spot on. A tribute to a large amount of work done by experimentalists and theorists.

Testing the Standard Model Prediction of top mass • EWK precision measurements (Tevatron, LEP, SLC. . ) • Radiative corrections (theory) SM Top mass predictions (SM) Top W Dmtop /mtop = 0. 3% W New physics X W W Dm. W /m. W = 0. 02% Top discovery

Testing the Standard Model Prediction of Higgs mass • MW and Mtop precision meas. s • Radiative corrections SM ar. Xiv: 1803. 01853 Dm. H /m. H = 0. 2% Prediction of Higgs mass Top W ar. Xiv: 1803. 01853 W Higgs discovery New physics X W W ar. Xiv: 1803. 01853 ~20 years of precision meas. s: quantitatively test consistency of SM rad. corrections Higgs redefines needs and precision targets (e. g. m. W)

Testing the Standard Model Electroweak precision measurements ar. Xiv: 1803. 01853 Strong interactions Running as(Q) Flavor Anomalies

Testing the Standard Model Higgs production and decays: any deviation from SM new physics models SM prediction Observed all major Higgs production modes! Consistent with SM. All couplings to high mass particles measured. Next challenge: muon, charm, . . .

Searching for New Particles Direct searches at LHC: No new physics found anywhere looked Simplified signatures covered to high masses, but unexplored models at low mass

Standard Model @ 50: Successes Completion of the Standard Model

The Standard Model – Epilog WHY ? • • Mass 6 quarks 3 families Forces Anti-matter Neutrinos …

The Standard Model – Epilog Visible Universe Invisible Universe (Dark Universe) ?

Energy Frontier Colliders Searching for an elegant and complete theory peeling inward peeling backward in time

Energy Frontier Colliders Searching for an elegant and complete theory Ele ga nt Th e or y peeling inward peeling backward in time

Energy Frontier Colliders 1970 SPEAR (e+e-) PEP (e+e-) PETRA (e+e-) TRISTAN (e+e-) SLC (e+e-) LEP (e+e-) 1980 1990 2000 2010 2020 2030 Discovery of an elementary particle HERA (e+p, e-p) ISR (pp) Spp. S (pp-bar) Tevatron (pp-bar) LHC (pp) ? Now What should be the next energy frontier collider?

Physics Case Higgs as a tool for new physics Direct new physics searches LHC ILC + LHC 14 Te. V pp 100 Te. V pp CERN Yellow Reports (2017) 14 Te. V pp 100 Te. V pp

Accelerator / Detector: R&D and Construction Fermilab CERN Tevatron (1985 -2011) _ pp: 2 Te. V R&D and Construction LHC (2009 -2038) pp: 7, 8 Te. V 14 Te. V (decision) Future collider

What should be the next energy frontier collider? Global projects 30 – 50 km International linear collider (ILC) 250 Ge. V Higgs factory 1 Te. V High Energy LHC ~100 km FCC: ee, ep, pp (~100 Te. V) 50 km CLIC (ee): 380 Ge. V Te. V CERN Japan 27 km LHC Europe China ~100 km circular collider e+e- CEPC (250 Ge. V Higgs factory) pp Spp. C (~100 Te. V)

The world community updates their vision The world may not be able to build multiple “global” projects at once World community’s effort Science strategy and technology development Europe U. S. 1 st 2006 2008 2 nd 2013 2014 3 rd 2020 TBD • Europe (nearly 2 year process) 1. Preparatory Group (community’s input) 2. Strategy Group 3. CERN Council • U. S. (nearly 2 year process) 1. 2. 3. 4. Snowmass (community’s input), organized by DPF Particle Physics Project Prioritization Panel (P 5) High Energy Physics Advisory Panel (HEPAP) DOE/NSF

U. S. Strategic Plan: Snowmass + P 5 (2012 – 2014) Five Intertwined Scientific Drivers were distilled from the results of a yearlong community-wide study: 2013 2002 2015 2011 2008 2004

U. S. Strategy: P 5 Report (2014) Various facilities prepared / DUNE

European Strategic Plan (2018 – 2020) Europe U. S. 1 st 2006 2008 2 nd 2013 2014 3 rd 2020 TBD Timeline • 2018 • Sept. : Formation of Physics Preparatory Group • Dec. : World-wide community input • 2019 • Briefing Book • 2020 • Draft strategy by European Strategy Group • Strategy adopted by the CERN Council (May)

DPF Whitepaper to European Strategy Group Dates in 2018 Process Until Oct. 8 th Collect input from the US DPF community via email at dpfstrategy@fnal. gov Oct. 9 th – Nov. 11 th Draft a white paper Nov. 12 th – Dec. 2 nd Post the draft for feedback from the DPF community Dec. 3 rd – Dec. 16 th Finalize the draft Dec. 17 th Submit paper to ESG and post it on the DPF bulletin site 35

DPF Whitepaper Categories and Editors Categories Editors General Editors Kate Scholberg, Elizabeth Worcester, Joe Incandela Use of the Higgs boson as a tool for further inquiry Sally Dawson, Markus Klute Investigation of the physics of neutrino mass Andre de Gouvea, Sam Zeller Investigation of the physics of dark matter Rouven Essig, Prisca Cushman Investigation of the physics of dark energy and cosmic inflation Scott Dodelson, Bhuv Jain Exploration of new particles, interactions, and physics principles Bogdan Dobrescu, Zachary Marshall Future accelerators Tao Han, Meenakshi Narain, Vladimir Shiltsev Computing Oliver Gutsche, David Miller Detector R&D Ron Lipton, Kim Palladino Other

Next U. S. Strategic Plan: How and When? • 2017 DPF meeting at Fermilab – Presentations and a panel discussion on status of U. S. strategy and plan to update the strategy. – The P 5 plan (2014) has met success in the community, the agencies, and the stakeholders, and defines the U. S. program that is currently being executed. – The right time to initiate the studies for an update to the U. S. strategy would be sometime after the CERN Council has adopted the European Strategy. • DPF is considering 2020 and 2021 for the next Snowmass studies. • Initial planning discussions (for format and timeline) will take place at the April 2019 APS meeting in Denver (April 13 – 16). 37

Initial Planning Discussions for the Snowmass • Town Hall meeting for the Snowmass Process during the 2019 APS April Meeting • Tentative meeting time – Saturday, April 13, 2019 • Tentative meeting agenda – Introduction / Summary of DPF White paper to ESG – Lessons learned from the 2013 Snowmass • Energy Frontier • Intensity Frontier • Cosmic Frontier • Theory Frontier • Capabilities Frontier • Instrumentation Frontier • Computing Frontier • Education and Outreach – Format and Timeline for the next Snowmass