Split Supersymmetry: Signatures of Long-Lived

Gluinos

• Intro to Split SUSY• Long-Lived Gluinos @ LHC• Long-Lived Gluinos in Cosmic Rays

JLH, Lillie, Masip, Rizzohep-ph/0408248

SUSY05 Durham J. Hewett

Split SUSY Intro & Philosophy– See Savas Dimopoulos, Thurs plenary

Arkani-Hamed, Dimopoulos hep-ph/0405159

Giudice, Romanino hep-ph/0406088

Split SUSY Collider Phenomenology– See SUSY/Higgs Parallel, Friday afternoon Numerous authors & papers!

Split SUSY Dark Matter– See Astro Parallel, Wed afternoon Numerous authors & papers!

Split Supersymmetry: Philosophy

• SUSY is irrelevant to the hierarchy problem– Cosmological constant problem suggests fine-tuning

mechanism may also apply to the gauge hierarchy

• Break SUSY at the GUT scale– Scalars become ultra-heavy (except 1 light Higgs): mS ~ 109-12 GeV

– Fermions protected by chiral symmetry

• Phenomenological Successes:– Retain gauge coupling unification

– Higgs mass predicted to be `heavier’: mH ~ 120-150 GeV

– Flavor & CP problems are automatically solved– Proton decay is delayed (occurs via dimension-6 operator)

• Collider signatures & Dark Matter implications substantially different!

This ties into the Landscape picture

Courtesy of Linde

Fine-tuning does occur in nature

2001 solar eclipse as viewed from Africa

• Whether you buy into this program or not, it behooves us to examine the collider signals of Split SUSY

• We don’t know what the LHC is going to discover and we need to be prepared!

Gauge Coupling Unification: (See Dimopoulos)

1 TeV MSSM @ 1-loop

Split SUSY @ 1-loop

mS = 109 GeV

Arkani-Hamed, Dimopoulos hep-ph/0405159

Higgs Mass Prediction: (See Dimopoulos)

mH = 130-170 GeV for mS > 106 GeV

Measurement of gaugino Yukawas determines SUSY breaking scale

Arvanitaki, Davis, Graham, Wacker hep-ph/0406034

Higgs Mass @ 1-looptan = 50

1

Error bands reflect mt & s errors

LSP (10) is still dark matter candidate (See

Dimopoulos)

10

10

10

10

hf,V

f,V(*)-

V

V(*)

Main annihilation channels:•No scalar exchange•depends on fewer parameters

Points which satisfy WMAP relic abundance constraint

Pierce, hep-ph/0406144

+ co-annihilation graphs very efficient!!

Collider Phenomenology: EW Gauginos

• Produced in pairs via Drell-Yan 1

0 is LSP• Only open decay channel:

(20)

W (Z)

10

No cascade decays!

Tri-lepton signature sill valid, exceptGaugino couplings (at the TeV scale) are smaller than those in MSSM

GUT tests require accurate coupling measurements @ ILC

Collider Phenomenology: Gluinos

• Pair produced via strong interactions as usual• Gluinos are long-lived• No MET signature• Interesting detector signatures

g~q~

q

q

10

Gluino lifetime:

ranges from ps to age of the universe for TeV-scale gluinos (Cosmological constraints)

JLH, Lillie, Masip, Rizzohep-ph/0408248

Gluinos as LSP:Baer etal 1998

~ ps, decays in vertex detector•ps < < 100 ns, decays in detector > 10-7 s, decays outside detector bulk of parameter space!

Gluino Hadronization and Fragmentation

Gluino hadronizes into color singlet R-hadron

• R is neutral: energy loss via hadronic collisions as it propagates through detector

• R is charged: energy loss via hadronic interactions and ionization

• R flips sign: hadronic interactions can change charge of R, can be alternately charged and neutral! ionization tracks may

stop & start!

Fragmentation is uncertain: slight preference for neutral R-hadrons

Prob < Prob

m - m > m

Energy Loss in the Detector

• Hadronic Interactions: RN RX

– model with constant differential or triple pomeron– deposits few 100 MeV per interaction

Mean interaction length: ~ 19 cm in Fe 100 GeV R with E = 400 GeV, deposits at most 6.4 GeV in CDF

• Ionization: Bethe-Bloch Eqn– sizeable energy loss for slow moving R-hadrons– fast moving R-hadron deposits ~ 1.5 GeV

~ k

k typically ~ (0.1-0.35 GeV)

Either case: amount of energy deposition may escape triggers!

Interactions due to light constituents energy loss E ~

Average speed of gluino @ Tevatron

Case 1: constant differentialCase 2: triple pomeron

Gluino Production:

= 0.2 mgluino as suggested by NLO

Searches:

1. Stable, neutral R-hadron: most challenging case!• Energy loss via hadronic ints unobservable• Consider Gluino pair + jet production

• Trigger on high pT jet

• Since scalars decouple, use QQ + jet productionMonojet Searches:CDF:

One central jet ET > 80 GeV

MET > 80 GeVRun I 284 events observed 274 16 expected New Physics < 62 events

Mgluino > 170 GeV

215 GeV (scaled Run II with 1 fb-1)

LHC: one central jet ET > 750 GeV MET > 750 GeV expect ~ 4200 bckgnd events

Mgluino > 1.1 TeV for 100 fb-1

Gluino pair + jet cross section

Tevatron Run II (1 fb-1) LHC

At LO with several renormalization scales

2. Stable, charged R-hadrons:– time of flight for slow moving (relative to = 1)

ranges from 0.8 (m = 200 GeV) to 0.4 (m = 500 GeV) @ Tevatron

– high ionization energy loss for fast moving

charged R-hadrons can be tracked as they traverse the detector– Consider only gluino pair production w/o bremstrahlung

– CDF:Heavy charged stableParticle search yieldsmgluino > 270 GeV (Run I)

430 GeV (Run II with 2 fb-1)

Ionization loss (dE/dx) for ≤ 0.85:Mgluino > 300 GeV (Run I)

LHC: Scale CDF results mgluino > 2.4 TeV

3. Alternating sign R-hadrons (flippers)– Re-fragmentation after every hadronic interaction– highly model dependent!!!– worst case scenario is monojet signature from 100%

neutral R-hadrons– Signature: off-line analysis of monojet signal

reveal charged tracks that stop & start puffs of ionization energy deposition!

R-hadrons in Cosmic rays: Signatures in IceCube

• p+N gluino pairs• R-hadrons form• interact with

nucleons in atmosphere & ice

• Showering R-hadrons very energetic!

• Deposit ~ TeV in atmosphere

• Deposit ~ 40 TeV in IceCube

Number of events expected @ IceCube

Not competitive with colliders

Summary

• Split SUSY predicts novel collider (& cosmological) signatures

• Gaugino decays differ substantially from MSSM• Need to re-examine gaugino searches• Worst case scenario: R-hadron neutral & stable

– Tevatron search reach up to mg ~ 270 GeV

– LHC search reach up to mg ~ 1 TeV

• Search reach extended if R-hadrons charged• Cosmic ray signals not quite competitive with

colliders

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