Kaonic nuclear clusters with ALICE E. Fragiacomo INFN Trieste Convegno Nazionale sulla Fisica di ALICE Vietri sul Mare – 30 maggio 2006

PWG2 - 23/05/06 Enrico Fragiacomo 2 of 14 Outline Kaonic nuclear clusters (KNC) Brief review on theoretical and experimental results Perspectives in relativistic heavy ion collisions Dynamical generation of the (1405) Afterburner implementation of (1405) in AliRoot

PWG2 - 23/05/06 Enrico Fragiacomo 3 of 14 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 ) In this realm, (1405) is the simplest KNC (K - p system) and it is used as a doorway for heavier (K - pp, K - ppp,…) clustering

PWG2 - 23/05/06 Enrico Fragiacomo 4 of 14 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 (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/ Kaonic Nuclear Clustering

PWG2 - 23/05/06 Enrico Fragiacomo 5 of 14 Nuclear densities in KNC Yamazaki, Doté, Akaishi, nucl-th/ He density for comparison ppnK - ppnK - K -

PWG2 - 23/05/06 Enrico Fragiacomo 6 of 14 KNC can be produced via: direct reactions, such as A(K -,n) or A(K -, N) E.g. K - d -> [K - pn] -> (1116)n cascade reactions: E.g on 4 He: p + n -> (1405) + K 0 +p + ppn -> [pppK - ] + n (1116)pp Suggestions to identify clusters as residues ( fragments) after relativistic heavy-ion collisions (Yamazaki, Doté, Akaishi, nucl-th/ ) How are KNC produced

PWG2 - 23/05/06 Enrico Fragiacomo 7 of 14 Cascade production Yamazaki, Doté, Akaishi, nucl-th/

PWG2 - 23/05/06 Enrico Fragiacomo 8 of 14 How do KNC decay (1116) in coincidence with nucleons No (1405) Invariant mass analysis of the decay products used to reconstruct KNCs

PWG2 - 23/05/06 Enrico Fragiacomo 9 of 14 Experimental evidence 4 He(stopped K -,p)X Missing mass analysis (see next slide) Strange tri-baryon S 0 (3115) Suzuki et al, Phys Lett. B 597 (2004) 263 NE A(stopped K -, p) Invariant mass analysis (see next slide) K - pp decaying via p Agnello et al., Phys. Rev. Lett. 94, (2005)

PWG2 - 23/05/06 Enrico Fragiacomo 10 of 14 Experimental results NE Suzuki et al, ibidemAgnello et al., ibidem = 70 MeV -> = sec ~ 3 fm/c

PWG2 - 23/05/06 Enrico Fragiacomo 11 of 14 Dynamical generation of (1405) E. Oset, A. Ramos, Nucl. Phys. A635, 99 (1998) U PT calculations for the s-wave meson-nucleon interaction in the S = -1 sector Reproduces low-energy experimental cross sections E.g K - p -> K - p, - + -> - + Reproduces (1405) with one free parameter only (cut-off)

PWG2 - 23/05/06 Enrico Fragiacomo 12 of 14 Osets model implemented in AliRoot (E. Cattaruzza and EF) 1. Loops over all K - p (or ) combinations from Pythia 2. Calculates the interaction probability 3. Selects the interacting pairs and the interaction channel according to the probability 4. Modifies the particle stack (work in progress) Next step: introduce nuclear matter -> density dependence of in-medium N interaction (A.Ramos and E. Oset, nucl-th/ ) AliGenAfterBurnerOset

PWG2 - 23/05/06 Enrico Fragiacomo 13 of 14 Preliminary M (GeV/c 2 ) Entries

PWG2 - 23/05/06 Enrico Fragiacomo 14 of 14 Conclusions (milestones) Join the forum on KNC (immediate) Reconstruction of KNCs (within end of year) (e.g. (1405), K - pp -> (1116)p or K - K - pp -> ) Nuclear matter implementation (within summer)