Aspects of R-Hadrons

Aspects of R-hadrons

Aafke Kraan

Niels Bohr Institute, Denmark

Work done with help of: Peter Hansen Pavel Nevski Torbjorn¨ Sjostrand¨

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.1/35 – Supersymmetry models – R-hadron production – Hadronization – Other models

Outline

What is an R-hadron?

Searches for R-hadrons

Cosmological aspects

Interactions of R-hadrons in matter

GEANT 3 implementation

R-hadron signatures in ATLAS

Outlook and summary

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.2/35 Outline

– Supersymmetry models What is an R-hadron? – R-hadron production – Hadronization Searches for R-hadrons – Other models

Cosmological aspects

Interactions of R-hadrons in matter

GEANT 3 implementation

R-hadron signatures in ATLAS

Outlook and summary

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.2/35 Supersymmetry

Supersymmetry (SUSY): symmetry bosons fermions ¤ ¢£ For example: Quark ¡ squark ¡ ¤ ¢£ Electron ¥ selectron ¥ ¤ ¢£ Gluon ¦ gluino ¦

No sparticles observed £ SUSY must be broken Interactions mediating SUSY breaking can be: Messenger fields Gravitational origin of MSSM Gauge SUSY ( visible sector ) Anomalous ( hidden sector )

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.3/35 SUSY: conventional models

Most models predict universal gaugino masses at GUT scale: ¤ ¡ ¡ ¡ ¢ £ ¥ ¢ and RGE give at EW scale e.g.: £ ¢ ¡ ¡ ¢ ¢ ¢ ¦ ¦ ¦ £ ¢

In conventional models: Gluino is automatically heavy LSP is always neutral, colorless and non-interacting: neutralino ¤§¦©¨ sneutrino ¤§

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.4/35 SUSY: unconventional models

However, SUSY models exist with non-universal gaugino masses £ mass hierarchy is changed!

String-motivated models (Chen, Drees, Gunion e.a) GMSB models (Raby, Dimopoulos, Barbieri e.a.) Possibility: strongly interacting LSP: gluino or squark!

If R-parity conserved, LSP hadronizes to R−hadrons

If gluino LSP: If squark LSP:

¤ ¡

¤ ¡ ¡ ¡ ¦ ¡ ¡ ¡ R-mesons: R-mesons: ¡

¤ ¡ ¡ ¡ ¦ ¡ ¡ ¡ ¡ R-baryons: R-baryons: ¡

¤ ¦ ¦ R-gluinoballs: ¡

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.5/35 R-hadron pairs at LEP and LHC

Production at LEP: ¡

¤ ¤ ¡ £ Squark R-hadrons: ¥ ¥ ¡ ¡ ¡ ¤£¢ ¤

¤ ¤ ¢ ¡ ¡ £ £ Gluino R-hadrons: ¥ ¥ ¤ ¦ ¤ ¦ Production at LHC: ¡ ¡ ¤ ¤ ¤ ¤ ¤ ¤ ¡ £ £ £ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ Squark R-hadrons: ¦ ¦ ¡ ¡ , ¤ ¤ ¤ ¤ ¡ £ £ ¡ ¡ ¦ ¦ Gluino R-hadrons: ¦ ¦ ¦ ¦ ,

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.6/35 Hadronization

Coloured gluino or squark hadronizes to R-hadron. u ~ u o o c D T ~ g

o u R u π d + ~ + t d o e 1 K s Z, γ * s In ALEPH: s − * u K* − ~1 u e t π d

d o d ρ u d ~ + g R u ~+ T c Do Similar hadronization in ATLAS

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.7/35 Hadronization

Free parameters in hadronization model: Fragmentation function ¤ Probability to form ¦ ¦ bound states Effective spectator mass. ¤ Gluon constituent mass (for ¦ ¦ states )

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.8/35 Other models with heavy hadrons ¡ Leptoquarks: ¤ £ ¡ ¢ small Yukawa couplings ¥ ¡¦¥

¤ £

Universal extra dimensions: Exact momentum conservation in all dimensions leads to stable Kaluza-Klein excitations of SM ﬁelds. (T.Appelquist, H. Cheng, B.Dobrescu, 2000) Uniﬁcation theories in higher dimension (G.Ingelman, C.Wetterich, 1986) Other models include e.g.: heavy quarks, ’mirror’-fermions, ’shiny quarks’, etc.

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.9/35 Outline

What is an R-hadron? – Ordinary matter Searches for R-hadrons – Cosmic rays – Accelerators Cosmological aspects

Interactions of R-hadrons in matter

GEANT 3 implementation

R-hadron signatures in ATLAS

Outlook and summary

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.10/35 Search for R-hadrons in ordinary matter?

In the early periods of the galaxy: all particles have ca same average velocity, given by £

¢£ ¡ the virial theorem ( ¡ ). During cooling of the galaxy, particles get trapped in ordinary baryonic matter if: their interactions with matter is strong enough. ¥ ¢£ the mass is not too large ( ¤ GeV).

do not get trapped £ halo particles If R-hadrons formed in early universe, they should be trapped in ordinary matter!

Bound in nuclei £ heavy isotopes?

Bound in water £ heavy water (HRO)? Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.11/35 Search for R-hadrons in ordinary matter

R-hadron = Strongly Interacting Massive Particle (SIMP) Searches for SIMP’s in ordinary matter: Searches in isotopes, where SIMP’s bind with energy: ¢© ¢©¨

£ £ ¡ ¡ ¤ §

¡ ¡ ¥ ¦ pot ¢ kin ¢ ¥ ¢ ¢ £

Thus, largest for large and £ best binding in high Z nuclei ¥ ¢ ¢£ ¢£ ¡ H, Li, .., F, Na, Au, Fe searches: [ GeV] £ Iron meteorite searches: GeV Searches for anonamously heavy water: ¢£ Mass spectroscopy: TeV Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.12/35 Search for R-hadrons in cosmic rays

Searches by studying cosmic rays (dark matter searches) Balloon ﬂight and satelite searches Surface and underground laboratory experiments, e.g. MACRO experiment Limits on the ﬂux obtained

¢£ Interesting: ultra high energy ( eV!) cosmic rays observed £ explained by R-hadrons! No nearby sources present to explain such rays Air shower development suggests the rays to originate from strongly interacting, long-lived, neutral, massive particles £ R-hadrons?!

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.13/35 Accelerator searches for R-hadrons

Accelerator searches Limited to the c.o.m. energy Limited to charged particle searches (little studies on energy deposition in calorimeters!) Dependent on model for nuclear scattering (if any)

Interesting ALEPH search: Eur.Phys.J.C31, 221-242

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.14/35 Outline

What is an R-hadron?

Searches for R-hadrons

Cosmological apects: relic density

Interactions of R-hadrons in matter

GEANT 3 implementation

R-hadron signatures in ATLAS

Outlook and summary

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.15/35 Cosmological aspects

Searches for R-hadrons produced in the early universe seem negative...

How many R-hadrons would get trapped in matter?

¤£ ¢¢¡ ¢ ¡

¡ ¡ ¦ ¥¦

Calculate relic density in standard perturbative way: ¢

Calculate freeze-out density ¡ ¢

Expand the universe and calculate density § ¨ ¦

Density too high to have escaped detection...

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.16/35 Cosmological aspects

However, the gluino relic density may be smaller due to Enhancement of the gluino annihilation cross-section due to non-perturbative effects at threshold: For example: multiple gluon exchange between ¤ interacting ¦ (“Sommerfeld enhancement”) Unconventional inﬂation models Second time late inﬂation Lower reheating temperature Slow decay (can mean stable for detector experiments!)

Conclusion: no model-independent limits on the LSP from cosmology/astrophysics.

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.17/35 Outline

What is an R-hadron?

Searches for R-hadrons

Cosmological aspects

– Electromagnetic R-hadron interactions in matter – Nuclear

GEANT 3 implementation

R-hadron signatures in ATLAS

Outlook and summary

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.18/35 Interactions of R-hadrons in matter

Electromagnetic interactions (charged hadrons):

10 Ionization losses: 8

) 6 2 H2 liquid m

c 5 1 −

large for heavy (slow) particle. g 4 V

e He gas M

( 3

d C

/ Al

E Fe

d 2 Sn − Pb

1 0.1 1.0 10 100 1000 10 000 βγ = p/Mc

0.1 1.0 10 100 1000 Muon momentum (GeV/c)

0.1 1.0 10 100 1000 Pion momentum (GeV/c)

0.1 1.0 10 100 1000 10 000 Proton momentum (GeV/c) Multiple Coulomb scattering:

¢ £

large for heavy (slow) particle ¥ ¡ ¢¥¤

¨ £¢ © ¦¨§

Electromagnetic interactions are well-understood! Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.19/35 Interactions of R-hadrons in matter

Nuclear interactions (charged and neutral hadrons):

Central picture: [T.Sjostrand] ¨ ¨ ¨ ¨ ¢ ¡ ¢ R-hadron = passive gluino + interacting cloud. £ reservoir of kinetic energy! ¡¦¥

¢©¨ ¤ £ § ¦¤ ¡ Example: ¡ with M=100, E=150 GeV ¡ ¥ ¡ ¢ £ £ ¡ ¡

¤ ¤ ¡

¦ 0.7, so ¨ ¨ 1 GeV low!

To predict energylosses, we need to know

Nuclear interaction cross section Amount of energy lost per interaction

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.20/35 Nuclear scattering: general features

Nuclear interaction cross section depends on Energy of interaction Partial waves involved in scattering Reggeon or Pomeron mediated Presence of resonances £ Processes involved 2 £ 2 or 2 many Identity of scattered particles Available phasespace Amount of energy lost per interaction depends on Kinetic energy of kicked-out nucleon Amount of new particles

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.21/35 Nuclear scattering of light hadrons

An example: pion-proton scattering

Low energy ) 10 b m ( u u n o i t

u u c + e

p p p s π p ⇓ total s d s

d o r C

10 ++ uuu= ∆ + π p e lastic u u

π π π -1 2 d d 10 1 10 10 πp 1.2 2 3 4 5 6 7 8 9 10 20 30 40

πd 2.2 3 4 5 6 7 8 9 10 20 30 40 50 60 Center of mass energy (GeV)

d π

⇓ total

High energy ) b m ( u ⇓ n o i t – u c e π p

p p s total

d s o r

C 10

Pomeron – π p e lastic

π π -1 2 d 10 1 10 10 Laboratory beam momentum (GeV/c) Processes: Elastic scattering Charge exchange Inelastic scattering

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.22/35 Nuclear scattering of R-hadrons

What happens if we attach a gluino to the pion?? Color-state of hadron-cloud changed: color octet! Mass splitting between hadrons with same quark content but different spin is slighty inﬂuenced Effect is small £ neglect Resonance formation is inﬂuenced. Little information £ smeared out picture

No changes in Reggeon or Pomeron exchange, since heavy gluino acts only as spectator u u u u p p p p d d

Pomeron

u u d d R R R R g~ g~ Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.23/35 R-hadron scattering processes

Which processes? 12 M = 1 GeV

(GeV) 10 M = 50 GeV ε ¢ ¢ ¡

£ M = 100 GeV

8 M = 300 GeV ¤ ¤ ¤ £ ¡ ¥ £ ¢ ¢ 6

4 £ Small : assume only 2 ¡ £ £ 0 and processes 0 100 200 300 400 500 600 700 Plab(GeV/c) R-mesons (R) R-baryons (S) Pure elastic Pure elastic Charge exchange Charge exchange Inelastic Inelastic Baryon exchange

Ca 140 processes £ same rel. couplings (no CG coeff...)

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.24/35 Nuclear scattering cross sections

There are several problems... Exact size of R-hadrons unknown Approximation: assume R-hadron is black disk

Many different R-hadrons £ different cross sections! ¥ Approximation: assume only ¤ and quarks ¡ Phasespace: £ or £ scattering? ¡ Function constructed by studying £ and £

phasespace with ¡ Proposed total cross sections ¤ ¡ ¡ ¡ ¦ £ £ ¡ ¡ ¢ £ ¢ ¢ ¢ – : from -p data: ¢ 4 mbarn, 20 mbarn £ ¤ ¡ ¡ ¡ ¦ £ £ £ ¡ ¢ – : three active quarks now so = ¢

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.25/35 Energy losses per interaction

R-hadron energy losses ¡¡

¦ of kicked out-proton is lost. ¡ ¢

This energy is small ( 0.5 GeV), since ¦ of hadron cloud was small! Energy used for production of extra particles is lost ¤¤£ This energy is small ( ¢ )

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.26/35 Outline

What is an R-hadron?

Searches for R-hadrons

Cosmological aspects

R-hadron interactions in matter

GEANT 3 implementation

R-hadron signatures in ATLAS

Outlook and summary

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.27/35 R-hadron GEANT 3 implementation

Model implemented in GEANT3 Ca 140 processes implemented Seven new shower routines made

GEANT3 simulation tested and ready to be used

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.28/35 Outline

What is an R-hadron?

Searches for R-hadrons

Cosmological aspects

R-hadron interactions in matter

GEANT 3 implementation

R-hadron signatures in ATLAS

Outlook and summary

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.29/35 R-hadron traversing ATLAS ¡ ¡

Muon 10 m ¦ (R) 18 cm ¡ ¡ chambers ¡

¦ (S) 12 cm ¢¤£

Tiles ¦ (R) 90 cm ¢¤£

4 m ¡

+ + + ¦ (S) 60 cm Hadronic Tiles S p S n + calorimeter S p S+ p o + S p S n Example: Tiles 3 m Electro− LiAr S on So n – M=100 GeV magnetic LiAr o R p S n – P= 50 GeV calorimeter o p p π + LiAr R R 2 m – Ekin=12 GeV + o Presampler R n R p nuc ¡ Eloss 5-15GeV Magnet 1 m stopped? Tracking TRT punch through? Si strips Pixels 0 m Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.30/35 An R-hadron event in ATLAS

Example of an ¡ event in the ATLAS detector: ¤ = 300 GeV, = 14 TeV

ATLAS Atlantis Event: revent3 ATLAS Atlantis Event: revent3 10 2 Y (m) Y (m) 0 0 -2 -10

-10 0 X (m) 10 -2 0 X (m) 2

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.31/35 R-hadron signatures in ATLAS

Events probably selected by muon-trigger. Missing transverse energy due to large R-hadron mass.

heavily ionizing in e.g. TRT. ¨ ¡ ¢ meas meas distribution. Large TOF in muon-chambers. Characteristic longitudinal and transversal shower.

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.32/35 Outline

What is an R-hadron?

Searches for R-hadrons

Cosmological aspects

R-hadron interactions in matter

GEANT 3 implementation

R-hadron signatures in ATLAS

Outlook and summary

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.33/35 Outlook

Study how to obtain TOF information from muon chambers. Find out how to obtain calorimeter deposits associated with charged tracks. Generate full simulated signal events. Find out which background events to use. Make selection. Predict possible detection of R-hadrons in ATLAS.

Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.34/35 Summary

Heavy hadrons arise SUSY, extra dimensions, leptoquarks, etc.

R-parity conserving SUSY models £ R-hadrons. Searches for primordial heavy hadrons so far negative. Small relic density of R-hadrons possible. Electromagnetic interactions: easy. Model developed for R-hadronic nuclear interactions and implemented in GEANT3. Interesting signatures in ATLAS. Main problems:

tracking calorimeter deposit

time of ﬂight. Aafke Kraan, Januari 2004, Spatind,˚ Norway – p.35/35