Highly-Ionizing Particles in Supersymmetric Models

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Highly-Ionizing Particles in Supersymmetric Models John Ellis King’s College London & CERN

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Highly-Ionizing Particles in Supersymmetric Models. John Ellis King ’ s College London & CERN. Minimal Supersymmetric Extension of Standard Model (MSSM). Particles + spartners No highly-charged particles expected, BUT …. 2 Higgs doublets, coupling μ , ratio of v.e.v. ’ s = tan β - PowerPoint PPT Presentation

Transcript of Highly-Ionizing Particles in Supersymmetric Models

Page 1: Highly-Ionizing Particles in Supersymmetric Models

Highly-Ionizing Particles in Supersymmetric Models

John Ellis

King’s College London & CERN

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• Particles + spartners

• No highly-charged particles expected, BUT ….• 2 Higgs doublets, coupling μ, ratio of v.e.v.’s = tan β• Unknown supersymmetry-breaking parameters:

Scalar masses m0, gaugino masses m1/2, trilinear soft couplings Aλ, bilinear soft coupling Bμ

• Often assume universality:Single m0, single m1/2, single Aλ, Bμ: not string?

• Called constrained MSSM = CMSSM

Minimal Supersymmetric Extension of Standard Model (MSSM)

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Mass Reach as Function of Energy & Luminosity

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Lightest Supersymmetric Particle

• Stable in many models because of conservation of R parity:

R = (-1) 2S –L + 3B

where S = spin, L = lepton #, B = baryon #

• Particles have R = +1, sparticles R = -1:Sparticles produced in pairsHeavier sparticles lighter sparticles

• Lightest supersymmetric particle (LSP) stable

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Possible Nature of LSP

• No strong or electromagnetic interactionsOtherwise would bind to matterDetectable as anomalous heavy nucleus

• Possible weakly-interacting scandidatesSneutrino

(Excluded by LEP, direct searches)Lightest neutralino χ (partner of Z, H, γ)Gravitino

(nightmare for astrophysical detection)

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Scenarios for Metastable Sparticles

• Maybe R-parity not exact?– No stable sparticle

• Next-to-lightest sparticle (NLSP) may be long-lived– Could be charged or neutral

• Scenarios for long-lived NLSP:– Small mass difference from neutralino LSP– Gravitino LSP– Gluinos in split supersymmetry

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Energy Loss and RangeSingly-charged particles are

highly-ionizing if moving slowlySmall range in typical

Detector materials

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Next-to-Lightest Supersymmetric Particle (NLSP) ?

• In neutralino dark matter scenarios:– Lighter stau?

• Could be long-lived if mstau–mLSP small• In gravitino dark matter scenarios:– Lighter stau, selectron or sneutrino?– Lighter stop squark?– gluino, …?

• Naturally long-lived – Decay interaction of gravitational strength

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Parameter Plane in the CMSSM

Excluded because stau LSP

Excluded by b s gamma

Preferred (?) by latest g - 2

Assuming the lightest sparticleis a neutralino

WMAP constraint on CDM density

LHC

JE, Olive & Spanos

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Stau NLSP with Neutralino LSP

• Along coannihilation strip of CMSSM parameter space favoured by dark matter density

• Generally small stau-neutralino mass difference

• May well be < 2 GeV

• Favoured by LHCJE, Olive

LHC

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Stau NLSP with Neutralino LSP

• 2-, 3- or 4-body decays may dominate, depending on mstau–mLSP

• Lifetime > 100 ns for mass difference < mτ

Jittoh, Sato, Shimomura, Yamanaka: hep-ph/0512197

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Stau Lifetime in Gravitino Dark Matter Scenarios

• Gravitational-strength decay interaction

• Naturally

long

lifetime

Hamaguchi, Nojiri, De Roeck: hep-ph/0612060

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Sample Supersymmetric Parameter Plane with different NLSP Options

Lighter stau

Lighter selectron

Tau sneutrino

Electron sneutrino

In gravitino dark matter scenario

Ellis, Olive, Santoso: arXiv:0807.3736

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More Planes with different NLSPs

Lighter stau

Lighter selectron

Tau sneutrino

Electron sneutrino

In gravitino dark matter scenario

Ellis, Olive, Santoso: arXiv:0807.3736

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Gravitino Dark Matter Benchmark Models with Stau NLSP

De Roeck, JE, Gianotti, Moortgat, Olive, Pape :hep-ph/0508198

Many τ’s in final states

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Example of Stop NLSP in Gravitino Dark Matter Scenario

Requires ‘careful’ choice of parameters

Diaz-Cruz, JE, Olive, Santoso: hep-ph/0701229

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More Examples of Gravitino Dark Matter Scenarios with Stop NLSP

Requires ‘careful’ choice of parameters

– but quite generic

Diaz-Cruz, JE, Olive, Santoso: hep-ph/0701229

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Stop Lifetime in CMSSMwith Gravitino Dark Matter

2-bodydecays

3-bodydecays

Diaz-Cruz, JE, Olive, Santoso: hep-ph/0701229

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Stop the Lithium Problem

Notorious Lithium problem of Big-Bang NucleosynthesisCould be solved by metastable stop decays

Kohri, Santoso: arXiv:0811.1119

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Gluinos in Split Supersymmetry

• Long-lived because squarks heavy

• Possible gluino hadrons:Gluino-g, gluino-qqbar, gluino-qqq

• Is there a metastable charged gluino hadron?• Gluino hadrons may flip charge as they pass

through matter• Gluino mesons may change into baryons:–e.g., gluino-uubar + uud gluino-uud + uubar

Hewitt, Lillie, Masip, Rizzo: hep-ph/0408248

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GluinoProductionat the LHC

• Large cross section @ LHC

• Significant fraction of charged particles emerge from the detector

Hewitt, Lillie, Masip, Rizzo: hep-ph/0408248

Farrar, Mackeprang, Milstead, Roberts: arXiv:1011.2964

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Production at the LHC

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Kinematical Distributions for Stops

Pseudo-rapidity distribution Velocity distribution

Johansen, Edsjo, Hellman, Milstead: arXiv:1003.4540

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Typical Velocities & Ranges

De Roeck, JE, Gianotti, Moortgat, Olive, Pape: hep-ph/0508198

Hamaguchi, Nojiri, De Roeck: hep-ph/0612060

Some fraction of slow-moving charged particles

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Searches at the LHC

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CMS Search for Metastable Particles using Tracker only

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CMS Search for Metastable Particles using Tracker and TOF

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Water Trap Concept for Stopping Metastable Charged Particles

Feng & Smith: hep-ph/0409278

Hope it does not leak! Energy distribution

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Water Trap Concept for Stopping Metastable Charged Particles

Feng & Smith: hep-ph/0409278

Angular distribution Number of trapped particles

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Possible (Meta)stable Particle Stoppers

Hamaguchi, Nojiri, De Roeck: hep-ph/0612060

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Extract Cores from Surrounding Rock?

• Use muon system to locate impact point on cavern wall with uncertainty < 1cm

• Fix impact angle with accuracy 10-3

• Bore into cavern wall and remove core of size

~ 1cm × 1cm × 10m = 10-3m3

• Can this be done before staus decay?– Caveat radioactivity induced by collisions

– Several technical stops each year

• Not possible if lifetime ~104s, possible if ~106s?De Roeck, JE, Gianotti, Moortgat, Olive, Pape :hep-ph/0508198

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Summary

• Few prospects for multiply-charged sparticles

• Many prospects for long-lived singly-charged sparticles– Staus, stops, selectrons, …

• Some would be produced with low velocities, hence highly-ionizing

• Production rates within MoEDAL reach