The Physics Case for Particle Colliders at Energies Beyond LHC - PowerPoint PPT Presentation

The Physics Case for Particle Colliders at Energies Beyond LHC Snowmass 2013 Markus Luty University of California Davis

Conclusions • What unites us: focus on discovery • Lepton and proton colliders are remarkably complementary • A choice between unknowns

Conclusions (cont’d) 100 TeV pp machine: • Unprecedented reach for new physics, but there are low-energy loopholes • Best guess: most sensitive probe of tuning in SUSY High energy lepton machines: • Less energy reach, essentially no loopholes • Precision program (Higgs, top) • Best guess: most sensitive probe of tuning in composite Higgs models

The Standard Model With the discovery of the Higgs, we have experimentally established a theory that can be consistently extrapolated to the Planck scale. There is no guarantee of discovery. We are exploring the unknown. Can we justify continued exploration with expensive particle colliders?

Unanswered Questions • Naturalness New physics at TeV scale • Dark matter • Origin of masses and mixings • Matter-antimatter asymmetry • Inflation • Unification ...

Naturalness K. Wilson Elementary scalars are unnatural 126 2 = 175992038487088835203904637364744757 – 175992038487088835203904637364728881

Two Ideas SUSY Compositeness (includes extra dimensions) tuning in standard model

SUSY The most successful paradigm for physics beyond the standard model Most general feature of spectrum: High scale SUSY breaking: RGE + unification Low scale SUSY breaking: gauge mediation ⇒ jets + MET signature

SUSY at LHC LHC run 1 searches: no sign of SUSY Squark-gluino-neutralino model 2800 squark mass [GeV] ∼ 0 SUSY χ σ ATLAS Preliminary m( ) = 0 GeV Observed limit ( ± 1 ) theory 1 ∼ 2600 0 χ σ m( ) = 0 GeV Expected limit ( 1 ) ± ∫ exp 1 ∼ -1 0 χ L dt = 20.3 fb , s =8 TeV m( ) = 395 GeV Observed limit 1 2400 ∼ 0 χ m( ) = 395 GeV Expected limit 0-lepton combined 1 ∼ 0 m( χ ) = 695 GeV Observed limit 2200 1 ∼ 0 χ m( ) = 695 GeV Expected limit 1 ∼ 0 2000 -1 χ 7TeV (4.7fb ) m( ) = 0 GeV Observed 1 1800 1600 1400 1200 1000 800 800 1000 1200 1400 1600 1800 2000 2200 2400 gluino mass [GeV] LHC run 2 & HL-LHC: tremendous increase in reach 1/2 Squark-gluino grid, m = 0. s = 14 TeV MET/ HT >15GeV LSP Mass (GeV) [GeV] [pb] 4000 ATLAS Simulation Z axis [pb] σ 700 s =14 TeV -1 3000 fb discovery reach σ -1 3000 fb , 95% exclusion limit -1 300 fb discovery reach -2 ~ 10 g 600 -1 m 3000 fb , 5 discovery reach 3500 -1 σ 3000 fb exclusion 95% CL -1 -1 300 fb , 95% exclusion limit 300 fb exclusion 95% CL -1 300 fb , 5 discovery reach 0 1 500 σ ∼ -3 χ 10 3000 400 -4 10 2500 300 -5 Zn, sys=30% 10 2000 200 ATLAS Preliminary (simulation) 100 -6 1500 10 2000 2500 3000 3500 4000 100 200 300 400 500 600 700 800 m [GeV] ~ 0 ∼ ± ∼ q and Mass (GeV) χ χ 1 2

SUSY Naturalness? Tuning: ⇒ Many sensitive stop searches... CMS Preliminary CMS Preliminary [GeV] [GeV] ~ ~ ~ ∼ 0 ~ ~ ~ -1 8 TeV, 20 fb ∼ 0 pp → t t *, t → t χ -1 8 TeV, 20 fb 600 pp → t t *, t → t χ 600 1 -1 1 14 TeV, 300 fb (scenario A) 1-lepton channel -1 14 TeV, 300 fb (scenario A) 1-lepton channel -1 Based on SUS-13-011 14 TeV, 300 fb (scenario B) -1 Based on SUS-13-011 14 TeV, 300 fb (scenario B) 0 1 ∼ 0 1 χ ∼ χ m Estimated 5 σ discovery reach 500 m Estimated 5 σ discovery reach 500 = m W = m t = m W = m t 0 0 400 - m - m ∼ ∼ 0 0 400 - m - m χ χ ∼ ∼ 1 1 χ χ 1 1 ~ ~ m m ~ ~ m m t t t t 300 300 200 200 100 100 0 0 200 300 400 500 600 700 800 900 1000 200 300 400 500 600 700 800 900 1000 m [GeV] m [GeV] ~ ~ t t My rough summary: (b) (b) LHC run 1: probes 10% tuning LHC run 2: 1% tuning HL-LHC: another factor of 4

Scenarios Discovery: we know what to do... SUSY • Drink champagne • “We told you so” • Study the %#**! out of the signal • Assess what future facilities best leverage discovery No discovery: Do we keep going?

Cosmic Mysteries [H. Murayama Lepton-Photon 2013] 1991: Limits on the cosmic microwave anisotropy were pushing the limits of cold dark matter cosmology... COBE:

Fine Tuning! mit “Big Bang not yet dead but in decline” Times, Jan 14 (1991) Nature 377, 14 (1995) Bang! A Big Theory May Be Shot” A new study of the stars could rewrite the history of the universe Times, Jan 14 (1991) 1% tuning

SUSY at 100 TeV pp 10 jet + MET events 35 30 25 q H TeV L 20 100 TeV VLHC 15 m é 10 33 TeV LHC 5 LHC run 2, HL-LHC LHC run 1 0 0 5 10 15 20 25 30 35 m g H TeV L é T. Cohen, K. Howe, J. Wacker

⇒ SUSY at Colliders Tuning: Energy reach: • Hermetic “EW-ino scan” • Masses measured to 1% • Similar for sleptons Best hope for making quantitative connection between collider MET and DM

Compositeness Version 2.0: Higgs as pseudo Nambu-Goldstone boson from Higgs couplings Tuning: and precision EW How far can we probe?

Compositeness at Colliders � � � 300/fb � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 300/fb � � � � � � � � � � � � � � � � � � � � 3 TeV 3/ab � � � � � � � � � � � � � � � � � � � � � � � � � � � �� � � � � � � � � �� Draft � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � VLHC can discover resonances to ??? Probes naturalness only indirectly

Dark Matter Thermal relic ⇒ observed value for Motivates dark matter at TeV scale collider production direct detection freeze-out, indirect detection

DM at 100 TeV pp -19 10 /s] 3 D8 qq [cm -20 10 LHC7, 5/fb LHC14, 300/fb � -21 10 � LHC14, 3/ab � v> for pp33, 3/ab -22 10 pp100, 3/ab � 95% CL limit on < -23 10 SUSY WIMP -24 CTA Segue 10 6 σ Monojet, MadGraph, Parton-Level, pp -25 2x FermiLAT bb CTA Fornax 10 Wino (8 TeV) Wino (14 TeV) 5 Thermal relic value Wino (100 TeV) -26 CTA Halo 10 Higgsino (8 TeV) Higgsino (14 TeV) 4 -27 10 Higgsino (100 TeV) -1 100 TeV, 3000 fb , E > 3000 GeV 3 T -28 10 -1 14 TeV, 3000 fb , E > 900 GeV T -1 8 TeV, 40 fb , E > 450 GeV T -29 2 10 3 2 4 1 10 10 10 10 m [GeV] 1 � Effective DM 0 500 1000 1500 2000 2500 3000 3500 χ Mass [GeV] M. Low, L. Wang [preliminary]

Leptons vs. Hadrons Energy 10 TeV VLHC muon ILC 1000 ILC 500 CLIC 1 TeV ILC 250 10% 1% Precision

Data Makes us Smarter 19 MeV systematics �

More Study Needed! The ILC community has set the gold standard for documenting their machine and its physics reach. CLIC is also in good shape, but there are few studies for VLHC and muon collider. More such studies are needed as input to the decision about the next big step forward in the energy frontier.

How do we Decide? “Guaranteed discovery” is guaranteed mediocrity High energy lepton and proton colliders are extremely complementary Neither has a guarantee of discovery We have to decide. If X finishes its run and we have seen nothing beyond the measurements that are guaranteed, I will say: “We did the right thing.”