Prospects for SUSY at HL and HE LHC Howard Baer University of Oklahoma @
Supersymmetry stabilizes the EW sector of the SM and is actually supported by data via virtual effects: 1. gauge couplings, 2. m(t), 3. m(h) It also improves/adds to solutions of the following nu mass and see-saw scale • QCD, strong CP and PQ scale • dark matter • dark energy • baryogenesis • quantum gravity via (super)string theory • Fundamental prediction: new matter states- the superpartners- should exist not too far from m(weak)~m(W,Z,h)~100 GeV
But where is SUSY • LHC: m(gluino)>2 TeV • LHC: m(t1)>1 TeV • m(h)~125 GeV • compare: Barbieri-Giudice 3% naturalness: m(gluino)<~500 GeV; m(t1)<~500 GeV • LHC limits way beyond naturalness bounds • is SUSY unnatural? Is SUSY dead?
No • BG naturalness computed fine-tuning within multi-parameter SUSY effective theories • In more fundamental theories (e.g. SUGRA/string) all soft terms inter-dependent: computed as multiples of more fundamental gravitino mass m(3/2) • Then large cancellations in fine-tuning computation (e.g. focus point SUSY, but now via all soft terms) • More conservative measure which allows for cancellations: ∆ EW e.g. in string-motivated dilaton dominated SUSY breaking, √ then m 2 0 = m 2 3 / 2 with m 1 / 2 = − A 0 = 3 m 3 / 2 doesn’t make sense to take soft terms as independent
u ) tan 2 β Z / 2 = m 2 H d + Σ d d − ( m 2 H u + Σ u H u − Σ u m 2 − µ 2 ∼ − m 2 u − µ 2 tan 2 β − 1 naturalness: no large unnatural cancellations on RHS HB,Barger, Huang, Mustafayev, Tata, PRL109 (2012)161802 then: • µ ∼ 100 − 200 GeV • m 2 H u can be driven to natural via large top Yukawa • radiative corrections not too large m(t1)~1-3 TeV fine naturalness: only higgsinos need be ~100-200 GeV higgsino is LSP higgsino-like WIMP~100-200 GeV thermally underproduced as DM: augment with e.g. axion
4 10 mSUGRA ∆ EW = 3780 m 0 = 7025 . 0 GeV M Z (GeV) 3 m 1 / 2 = 568 . 3 GeV 10 A 0 = − 11426 . 6 GeV tan β = 8 . 55 RNS2 ∆ EW = 10 2 10 M Z 3 4 5 6 7 10 10 10 10 10 µ 2 (GeV 2 ) can this be how nature works? Green curve shows the actual fine-tuning needed by computer code to ensure m(Z)=91.2 GeV; this is highly implausible/unnatural: we consider it to be ruled out
radiative corrections drive m 2 H u from unnatural GUT scale values to naturalness at weak scale: radiatively-driven naturalness EWS not broken natural: EWS is barely broken unnatural
SUSY mu problem: mu term is SUSY, not SUSY breaking: expect mu~M(Pl) but phenomenology requires mu~m(Z) • NMSSM: mu~m(3/2); beware singlets! • Giudice-Masiero: mu forbidden by some symmetry: generate via Higgs coupling to hidden sector • Kim-Nilles: invoke SUSY version of DFSZ axion solution to strong CP: W 3 λφ 2 P Q H u H d /M P KN: PQ symmetry forbids mu term, but then it is generated via PQ breaking m 3 / 2 ∼ m 2 hid /M P Little Hierarchy due to mismatch between f a ⌧ m hid PQ breaking and SUSY breaking scales? ✓ 10 12 GeV Higgs mass tells us where ◆ m a ∼ 6 . 2 µ eV to look for axion! f a
How much tuning is too much? higgsinos should be accessible to ILC!
bounds from naturalness old BG/DG Delta_EW (3%) mu 350 GeV 350 GeV gluino 400-600 GeV 5-6 TeV t1 450 GeV 3 TeV sq/sl 550-700 GeV 10-20 TeV h(125) and LHC limits are perfectly compatible with 3-10% naturalness: no crisis!
There is a Little Hierarchy, but it is no problem µ ⌧ m 3 / 2
Prospects for SUSY at LHC: new signature list: • ˜ g ˜ g • ˜ t 1 ˜ t ∗ 1 • ˜ Z 1 ˜ Z 2 (higgsino pair production) • ˜ 2 ˜ W ± Z 4 (wino pair production)
Sparticle prod’n along RNS model-line at LHC14: higgsinos gauginos stops gluinos higgsino pair production dominant-but only soft visible energy release from higgsino decays largest visible cross section: wino pairs gluino pairs sharply dropping stops at bottom
gluino pair cascade decay signatures Current limits for m(Z1)~150 GeV: ∼ ~ ~ ~ χ pp g g , g t t 0 → → m(glno)>~2 TeV Moriond 2017 1 [GeV] 2000 CMS Preliminary -1 35.9 fb (13 TeV) 1800 miss SUS-16-033, 0-lep (H ) Expected T 0 1 ∼ χ SUS-16-036, 0-lep (M ) m 1600 T2 Observed SUS-16-037, 1-lep (M ) J SUS-16-042, 1-lep ( Δ φ ) 1400 SUS-16-035, 2-lep (SS) ≥ SUS-16-041, 3-lep ≥ 1200 1000 800 600 400 200 0 800 1000 1200 1400 1600 1800 2000 2200 m [GeV] ~ g
gluino pair cascade decay signatures Estimated HL-LHC reach for gluinos HL-LHC reach to m(glno)~2.8 TeV; RNS: m(glno)<~5-6 TeV HB, Barger, Huang, Gainer, Savoy, Sengupta, Tata: EPJC77 (2017) 499
LHC14 has some reach for gluino pair production in RNS; if a signal is seen, should be distinctive OS/SF dilepton mass edge apparent from cascade decays with z2->z1+l+lbar Altunkaynak et al.,PRD92 (2015) 035015
Gluino reach at LHC33: to about m(glno)~6 TeV (apologies: this work performed before HE-LHC energy -> 27 TeV) >=4 jets; >=2-b-jets;MET>1500 GeV HB, Barger, Gainer, Huang, Savoy, Serce, Tata, PRD96 (2017) 115008
Compare to natural SUSY model predictions evidently HE-LHC can cover all natural SUSY p-space!
Present limits on top squarks from LHC ~ ~ ~ ∼ pp t t , t t 0 → → χ Moriond 2017 1 900 [GeV] -1 CMS Preliminary 35.9 fb (13 TeV) 800 miss Expected SUS-16-033, 0-lep (H ) T 0 1 Observed ∼ χ SUS-16-036, 0-lep (M ) m 700 T2 SUS-16-049, 0-lep stop SUS-16-051, 1-lep stop 600 SUS-17-001, 2-lep stop Comb. 0-, 1- and 2-lep stop 500 400 300 200 100 m 0 ∼ χ 1 + m t = ~ m t 0 200 400 600 800 1000 1200 m [GeV] ~ t Evidently m(t1)>~1 TeV for m(LSP)~150 GeV * TeV-scale top squark needed for m(h)~125 GeV * Also needed for b-> s gamma
Prospects for top squarks in natural SUSY m(t1) can range up to 3 TeV with little cost to naturalness; the hunt for stops has only begun! HL-LHC reach extends to m(t1)~1.2-1.4 TeV
Reach of HL/HE-LHC for top squarks t 1 → b ˜ • ˜ W 1 ; ∼ 50% t 1 → t ˜ • ˜ Z 1 ; ∼ 25% t 1 → t ˜ • ˜ Z 2 ; ∼ 25% HE-LHC reach extends to m(t1)~3-3.8 TeV n(b-jets)>=2; MET>750 GeV HB, Barger, Gainer, Serce, Tata, PRD96 (2017) 115008
HE-LHC reach for t1 covers all natural SUSY p-space!
Distinctive same-sign diboson (SSdB) signature from SUSY models with light higgsinos! (soft) (soft) wino pair production This channel offers good reach of LHC14 for RNS; it is also indicative of wino-pair prod’n followed by decay to higgsinos HB, Barger, Gainer, Sengupta, Tata
HL-LHC reach for natural SUSY in SSdB channel • HL-LHC can cover all of nAMSB model; part of nHUM2/nGMM • not clear if HE-LHC is improvement since QCD backgrounds increase more than EW signal
See direct higgsino pair production recoiling from ISR (monojet signal)? typically 1% S/BG after cuts: very tough to do!
Z 1 ` + ` − ? What about pp → ˜ Z 1 ˜ Z 2 j with ˜ Z 2 → ˜ Han, Kribs, Martin, Menon, PRD89 (2014) 075007; HB, Mustafayev, Tata, PRD90 (2014) 115007; C. Han, Kim, Munir, Park, JHEP1504 (2015) 132
use MET to construct m^2(tau-tau) cut m(ditau)^2<0
Status of lljMET searches: new results from Atlas/CMS compare to CMS projected HL-LHC reach; cover much of p-space; not clear if HE-LHC helps since again QCD BG increase much more than EW signal
Conclusions: • SUSY with radiatively driven naturalness: still natural! • m(higgsinos)~100-300 GeV; m(t1)<3 TeV; m(gl)<5-6 TeV • LHC13 has only begun to probe RNS p-space • HL-LHC: coverage much of p-space via llj/SSdB for models with ino mass unification: complete coverage for nAMSB • mirage/gravity- mediation models can escape HL-LHC: M1~M2~M3 • HE-LHC (rs~27 TeV) will be required for complete coverage of mirage/ gravity mediation models via gluino pair and stop pair production
Why do soft terms take on values needed for natural (barely-broken) EWSB? string theory landscape? • assume model like MSY/CCK where µ ⇠ 100 GeV • then m ( weak ) 2 ⇠ | m 2 H u | • If all values of SUSY breaking field h F X i equally likely, then mild (linear) statistical draw towards large soft terms • This is balanced by anthropic requirement of weak scale m weak ⇠ 100 GEV Anthropic selection of m weak ∼ 100 GeV : If m W too large, then weak interactions ∼ (1 /m 4 W ) too weak weak decays, fusion reactions suppressed elements not as we know them
statistical draw to large soft terms balanced by anthropic draw toward red (m(weak)~100 GeV): then m(Higgs)~125 GeV and natural SUSY spectrum! Giudice, Rattazzi, 2006 HB, Barger, Savoy, Serce, PLB758 (2016) 113
statistical/anthropic draw toward FP-like region
Expectations for SUSY from statistical analysis of II-B string landscape: power law selection of soft terms anthropic draw of m(weak)~100 GeV HB, Barger, Serce, Sinha
panoramic view of reach of HL-LHC for natural SUSY Combined SSdB/lljMET searches may cover all Nat SUSY p-space at HL-LHC for models with ino mass unification; in mirage scenario, z2-z1 mass gap can be reduced and M2 can be much higher than in NUHM2
Good old m0 vs. mhf plane still viable, but needs mu~100-200 GeV as possible in NUHM2 instead of CMSSM/mSUGRA For models with ino mass unif’n, reach via SSdB may exceed glno pairs for high luminosity HB,Barger,Savoy, Tata; arXiv:1604.07438
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