Kaonic nuclear clusters with ALICE

1
Kaonic nuclear clusters with ALICE

• E. Fragiacomo
• INFN Trieste
• Convegno Nazionale sulla Fisica di ALICE
• Vietri sul Mare 30 maggio 2006

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Outline

• Kaonic nuclear clusters (KNC)
• Brief review on theoretical and experimental
  results
• Perspectives in relativistic heavy ion collisions
• Dynamical generation of the L(1405)
• Afterburner implementation of L(1405) in AliRoot

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What are KNC

• KNC are nuclear systems involving (K- or
  )
• e.g. K-p, K-pp, ... (single clusters),
  K-K-pp, K-ppn, ... (double clusters)
• Large binding energies (E 100 MeV)
• High densities (up to 4-9 r0)
• In this realm, L(1405) is the simplest KNC (K-p
  system) and it is used as a doorway for heavier
  (K-pp, K-ppp,) clustering

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From the theory point of view

• Phenomenological approaches for the N
  interaction, reproducing the N scattering
  data, kaonic hydrogen atom data and the binding
  energy and decay width of the L(1405)
• T. Yamazaki and Y. Akaishi, Nucl. Phys. B535
  (2002)
• Make use of phenomenological potentials.
• Obtain very high densities
• A. Doté et al., Phys. Lett. B590 (2004)
• Antisymmetrized Molecular Dynamics (AMD) method
  for light clusters
• A. S. Ivanov et al., nucl-th/0512037
• Kaonic Nuclear Clustering

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Nuclear densities in KNC
ppnK-
3He density for comparison
ppnK-K-
Yamazaki, Doté, Akaishi, nucl-th/0310085
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How are KNC produced

• KNC can be produced via
• direct reactions, such as A(K-,n) or A(K-,LN)
• E.g. K- d -gt K-pn -gt L(1116)n
• cascade reactions
• E.g on 4He
• p n -gt L(1405) K0 p
  ppn -gt pppK- n
• 
  L(1116)pp
• Suggestions to identify clusters as
  residues ( fragments) after relativistic
  heavy-ion collisions (Yamazaki, Doté, Akaishi,
  nucl-th/0310085)

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Cascade production
Yamazaki, Doté, Akaishi, nucl-th/0310085
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How do KNC decay

• L(1116) in coincidence with nucleons
• No L(1405)
• Invariant mass analysis of the decay products
  used to reconstruct KNCs

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Experimental evidence

• E471_at_KEK
• 4He(stopped K-,p)X
• Missing mass analysis(see next slide)
• Strange tri-baryon S0(3115)
• Suzuki et al, Phys Lett. B 597 (2004) 263

• FINUDA_at_DAFNE
• A(stopped K-, Lp)
• Invariant mass analysis(see next slide)
• K-pp decaying via Lp
• Agnello et al., Phys. Rev. Lett. 94, 212303
  (2005)

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Experimental results
E471_at_KEK
FINUDA_at_DAFNE
G 70 MeV -gt t 10-23 sec 3 fm/c
Suzuki et al, ibidem
Agnello et al., ibidem
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Dynamical generation of L(1405)

• E. Oset, A. Ramos, Nucl. Phys. A635, 99 (1998)
• UcPT calculations for the s-wave meson-nucleon
  interaction in the S -1 sector
• Reproduces low-energy experimental cross sections
  E.g K-p -gt K-p, S-p -gt S-p
• Reproduces L(1405) with one free parameter only
  (cut-off)

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AliGenAfterBurnerOset

• Osets model implemented in AliRoot (E.
  Cattaruzza and EF)
• Loops over all K-p (or pS) combinations from
  Pythia
• Calculates the interaction probability
• Selects the interacting pairs and the interaction
  channel according to the probability
• Modifies the particle stack (work in progress)
• Next step introduce nuclear matter -gt density
  dependence of in-medium N interaction (A
  .Ramos and E. Oset, nucl-th/9906016)

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Preliminary
Entries
MpS (GeV/c2)
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Conclusions (milestones)

• Join the forum on KNC (immediate)
• Reconstruction of KNCs (within end of
  year)(e.g. L(1405), K-pp -gt L(1116)p or K-K-pp
  -gt L(1116)L(1116))
• Nuclear matter implementation (within summer)