@ Supersymmetry stabilizes the EW sector of the SM and is actually - - PowerPoint PPT Presentation

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)
• nu mass and see-saw scale
• QCD, strong CP and PQ scale
• dark matter
• dark energy
• baryogenesis
• quantum gravity via (super)string theory

It also improves/adds to solutions of the following 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 m2

0 = m2 3/2 with m1/2 = −A0 =

√ 3m3/2

doesn’t make sense to take soft terms as independent

m2

Z/2 = m2 Hd + Σd d − (m2 Hu + Σu u) tan2 β

tan2 β − 1 − µ2 ∼ −m2

Hu − Σu u − µ2

naturalness: no large unnatural cancellations on RHS then:

• µ ∼ 100 − 200 GeV
• m2

Hu can be driven to natural via large top Yukawa

• radiative corrections not too large

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

m(t1)~1-3 TeV fine

HB,Barger, Huang, Mustafayev, Tata, PRL109 (2012)161802

10

10

10

10

10

10

10

10

µ2 (GeV2) MZ (GeV)

∆EW = 3780 mSUGRA m0 = 7025.0 GeV m1/2 = 568.3 GeV A0 = −11426.6 GeV tan β = 8.55 ∆EW = 10 RNS2 MZ

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 can this be how nature works?

natural: EWS is barely broken

unnatural

EWS not broken

radiative corrections drive m2

Hu from unnatural

GUT scale values to naturalness at weak scale: radiatively-driven naturalness

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: KN: PQ symmetry forbids mu term, but then it is generated via PQ breaking Little Hierarchy due to mismatch between PQ breaking and SUSY breaking scales? Higgs mass tells us where to look for axion! ma ∼ 6.2µeV ✓1012 GeV fa ◆

m3/2 ∼ m2

hid/MP

fa ⌧ mhid

W 3 λφ2

P QHuHd/MP

How much tuning is too much? higgsinos should be accessible to ILC!

bounds from naturalness (3%)

• ld BG/DG

Delta_EW 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 ⌧ m3/2

Prospects for SUSY at LHC:

new signature list:

• ˜

g˜ g

• ˜

t1˜ t∗

1

• ˜

Z1 ˜ Z2 (higgsino pair production)

• ˜

W ±

2 ˜

Z4 (wino pair production)

Sparticle prod’n along RNS model-line at LHC14: higgsino pair production dominant-but only soft visible energy release from higgsino decays largest visible cross section: wino pairs gluino pairs sharply dropping

higgsinos gauginos gluinos stops

stops at bottom

gluino pair cascade decay signatures

[GeV]

g ~

m

800 1000 1200 1400 1600 1800 2000 2200

[GeV]

χ ∼

m

200 400 600 800 1000 1200 1400 1600 1800 2000

CMS Preliminary

1

χ ∼ t t → g ~ , g ~ g ~ → pp

Moriond 2017

(13 TeV)

• 1

35.9 fb

Expected Observed

)

SUS-16-033, 0-lep (H )

SUS-16-036, 0-lep (M )

SUS-16-037, 1-lep (M ) φ Δ SUS-16-042, 1-lep ( 2-lep (SS) ≥ SUS-16-035, 3-lep ≥ SUS-16-041,

Current limits for m(Z1)~150 GeV: m(glno)>~2 TeV

gluino pair cascade decay signatures

HL-LHC reach to m(glno)~2.8 TeV; RNS: m(glno)<~5-6 TeV Estimated HL-LHC reach for gluinos

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

>=4 jets; >=2-b-jets;MET>1500 GeV

HB, Barger, Gainer, Huang, Savoy, Serce, Tata, PRD96 (2017) 115008

(apologies: this work performed before HE-LHC energy -> 27 TeV)

Compare to natural SUSY model predictions

evidently HE-LHC can cover all natural SUSY p-space!

Present limits on top squarks from LHC

[GeV]

t ~

m

200 400 600 800 1000 1200

[GeV]

1

χ ∼

m

100 200 300 400 500 600 700 800 900

CMS Preliminary

1

χ ∼ t → t ~ , t ~ t ~ → pp

Moriond 2017

(13 TeV)

• 1

35.9 fb

Expected Observed

)

miss T

SUS-16-033, 0-lep (H )

T2

SUS-16-036, 0-lep (M SUS-16-049, 0-lep stop SUS-16-051, 1-lep stop SUS-17-001, 2-lep stop

• Comb. 0-, 1- and 2-lep stop

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

HE-LHC reach extends to m(t1)~3-3.8 TeV

HB, Barger, Gainer, Serce, Tata, PRD96 (2017) 115008

n(b-jets)>=2; MET>750 GeV

• ˜

t1 → b ˜ W1; ∼ 50%

• ˜

t1 → t ˜ Z1; ∼ 25%

• ˜

t1 → t ˜ Z2; ∼ 25%

HE-LHC reach for t1 covers all natural SUSY p-space!

Distinctive same-sign diboson (SSdB) signature from SUSY models with light higgsinos!

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

(soft) (soft)

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!

Han, Kribs, Martin, Menon, PRD89 (2014) 075007; HB, Mustafayev, Tata, PRD90 (2014) 115007;

• C. Han, Kim, Munir, Park, JHEP1504 (2015) 132

What about pp → ˜ Z1 ˜ Z2j with ˜ Z2 → ˜ Z1`+`− ?

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 ⇠ |m2

Hu|

• If all values of SUSY breaking field

hFXi equally likely, then mild (linear) statistical draw towards large soft terms

• This is balanced by anthropic requirement
• f weak scale mweak ⇠ 100 GEV

Anthropic selection of mweak ∼ 100 GeV: If mW too large, then weak interactions ∼ (1/m4

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!

HB, Barger, Savoy, Serce, PLB758 (2016) 113

Giudice, Rattazzi, 2006

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

HB,Barger,Savoy, Tata; arXiv:1604.07438

For models with ino mass unif’n, reach via SSdB may exceed glno pairs for high luminosity

m (GeV)

Typical spectrum for low ∆EW models

first/second generation matter scalars stops, sbottoms, gluinos

wino

bino Higgs,higgsinos gauge bosons

natural gravity mediation natural AMSB natural mirage mediation