The Smoking Gun of BNV Colour Topologies and String Hadronization - - PowerPoint PPT Presentation

ECFA LC Workshop 2003

The Smoking Gun of BNV

Colour Topologies and String Hadronization in Baryon Number Violating Supersymmetry

P . Skands (speaker) & T. Sjöstrand, Lund University. Nucl.Phys.B659:243,2003 ; hep-ph/0209199

The Smoking Gun of Baryon Number Violation, P . Skands – p.1/18

Overview

• 1. BNV SUSY: Quick Intro.
• 2. BNV SUSY in PYTHIA.
• 3. Colour topologies and hadronization.
• 4. Properties and predictions.
• 5. Conclusion.

The Smoking Gun of Baryon Number Violation, P . Skands – p.2/18

BNV SUSY: Quick Introduction

Most general (MSSM) superpotential:

• ✁

But

+

makes bad cocktail!

The Smoking Gun of Baryon Number Violation, P . Skands – p.3/18

BNV SUSY: Quick Introduction

Most general (MSSM) superpotential:

• ✁

But

+

makes bad cocktail! To save proton, ,

, or

• cons. imposed.
• ✁

CDM candidate, but no deep motivation.

and

more robust with higher dimension operators.

No clear-cut answer.

The Smoking Gun of Baryon Number Violation, P . Skands – p.3/18

BNV SUSY: Quick Introduction

Baryon Number Violation in Superpotential:

• ✁

(

= colour,

= generation)

Couplings between chiral multiplets.

Sfermions: 2-body decays. Gauginos/Higgsinos: 3-body decays (via sfermion resonances).

‘baryonic’ colour flow.

(This talk is not about BNV in production.)

The Smoking Gun of Baryon Number Violation, P . Skands – p.4/18

Overview

• 1. BNV SUSY: Quick Intro.
• 2. BNV SUSY in PYTHIA.
• 3. Colour topologies and hadronization.
• 4. Properties and predictions.
• 5. Conclusion.

The Smoking Gun of Baryon Number Violation, P . Skands – p.5/18

BNV SUSY in PYTHIA

UDD

• ✁

:

200 new decay chanels

,

,

,

Partial widths: tree-level ME’s, massive

and

. Momentum distributions: isotropic 3-body phase space (good approx. when intermediate propagators way off shell, worse when only slightly off shell). Final state parton multiplicity increased by subsequent showers. Only MSSM pair production included.

The Smoking Gun of Baryon Number Violation, P . Skands – p.6/18

Overview

• 1. BNV SUSY: Quick Intro.
• 2. BNV SUSY in PYTHIA.
• 3. Colour topologies and hadronization.
• 4. Properties and predictions.
• 5. Conclusion.

The Smoking Gun of Baryon Number Violation, P . Skands – p.7/18

Colour topologies

‘Ordinary’ colour topology ‘Baryonic’ colour topology (e.g.

• ☛

): (e.g. ):

How does such a system fragment? Could a Baryon excess be observed?

The Smoking Gun of Baryon Number Violation, P . Skands – p.8/18

Colour topologies and hadronization

Fundamental properties of QCD vacuum suggest string picture still applicable. String energy minimization + dipole pic- ture

• picture of 3 string pieces meet-

ing at a ‘string junction’.

(Warning: This picture was drawn in a “pedagogical projection” where distances close to the center are greatly exaggerated!)

The Smoking Gun of Baryon Number Violation, P . Skands – p.9/18

The Smoking gun!

The movement of the string junction is crucial, it is the smoke of the BNV gun! A junction is a topological feature of the string confinement field:

• ✂
• . Each string piece

acts on the other two with a constant force,

.

• in junction rest frame (JRF) the angle is

120

between the string pieces. Or better, ‘pull vectors’ lie at 120

:

• ✂✎✍

(since soft gluons ‘eaten’ by string)

The Smoking Gun of Baryon Number Violation, P . Skands – p.10/18

Fragmentation

The movement of the string junction is crucial, it is the smoke of the BNV gun!

• ✞
• ✠✟

• ✍

• ☎

• ✔

First 2 pieces fragmented outwards–in, junction baryon formed around junction, last string piece fragmented as

• rdinary

string.

The Smoking Gun of Baryon Number Violation, P . Skands – p.11/18

Intermezzo: more complicated topologies

Stop pair production at an LC:

a) 2 J baryons b) No J baryons

Select: a) or b) based on string length measure.

The Smoking Gun of Baryon Number Violation, P . Skands – p.12/18

Intermezzo: more complicated topologies

Stop pair production at an LC:

a) 2 J baryons b) No J baryons

Select: a) or b) based on string length measure.

0.2 0.4 0.6 0.8 1 1 2 3 4 5 6

γstop P

JJ

• annihilation

No junction baryons JJ

• string

2 junction baryons JJ

• perturbative breakup

2 junction baryons Pythia 6210 mstop= 50 GeV

The Smoking Gun of Baryon Number Violation, P . Skands – p.12/18

Intermezzo: more complicated topologies

Colour flow in gluino decays:

Selected according to (off–shell) resonance propagators.

The Smoking Gun of Baryon Number Violation, P . Skands – p.13/18

Overview

• 1. BNV SUSY: Quick Intro.
• 2. BNV SUSY in PYTHIA.
• 3. Colour topologies and hadronization.
• 4. Properties and predictions.
• 5. Conclusion.

The Smoking Gun of Baryon Number Violation, P . Skands – p.14/18

Properties and Predictions

Dependence on Fragmentation assumptions:

Default Fragmentation: Least Energetic Last Junction Pull: Enorm → ∞ Junction Pull: Enorm = 0.5 Junction Pull: CM Energies Junction Rest Frame = String CM

Primary Hadrons Junction Baryons <N>DEF = 21.63 <N>LEL = 21.88 <N>→ ∞ = 21.58 <N>0.5 = 21.67 <N>CME = 21.74 <N>SCM = 21.88

Pythia 6209 mχ = 96 GeV χ

~ 1 → u d s

pCM [GeV] dN/dpCM

10

• 2

10

• 1

1 10 5 10 15 20

Description is assymmetric but differences are small.

The Smoking Gun of Baryon Number Violation, P . Skands – p.15/18

Properties and Predictions Junction fragmentation implies:

Pythia 6209 - Junction Baryons Pythia 6209 - ″Ordinary″ Baryons Herwig 6301 - Junction Baryons Herwig 6301 - ″Ordinary″ Baryons

<Nbary>Pythia=3.4 <Nbary>Herwig=4.5

mχ = 96 GeV χ

~ 1→ u d s

pCM [GeV] dN/dpCM

10

• 2

10

• 1

5 10 15 20

if leading jets are well separated, junction will be slow, and junction baryon will be at low momenta:

The Smoking Gun of Baryon Number Violation, P . Skands – p.16/18

Overview

• 1. BNV SUSY: Quick Intro.
• 2. BNV SUSY in PYTHIA.
• 3. Colour topologies and hadronization.
• 4. Properties and predictions.
• 5. Conclusion.

The Smoking Gun of Baryon Number Violation, P . Skands – p.17/18

Conclusion

A model for BNV-SUSY allowing detailed studies available in PYTHIA. Special attention given to the non- perturbative aspects. Hadronization based

• n physical picture shows new aspects.

Generic prediction (apologies to particle ID people!): The smoking Gun — slow baryons. Junction fragmentation also used for multi- ple interactions, see friday morning talk in QCD/Generators session.

The Smoking Gun of Baryon Number Violation, P . Skands – p.18/18