DAE-HEP, IIT Guwahati Dec,2014

Transcription

1 DAE-HEP, IIT Guwahati Dec, Strange Hyperon Productions at LHC energy Purabi Ghosh Fakir Mohan University, Balasore

2 PLAN OF TALK: Introduction Strange particles and Relativistic Heavy Ion Collisions Processes for strange quark and hadrons (mesons and Hyperons-Lambda, Sigma) productions Rate of strange productions at AGS, SPS, RHIC and LHC energies Strange quark production and evolution in QGP medium Strange baryon (Lambda and Sigma) productions and evolution in Hadronic medium Summary and Outlook

3 INTRODUCTION: 0 0 Strange mesons like K, K, K, K and also hyperons like,,, all isospin components act as good probes to determine the nature of the medium formed in Relativistic Heavy Ion Collision experiments performed at SPS, RHIC and LHC A decade ago strangeness to entropy ratio in terms of K / and / was thought as a good signal for detect the QGP formation in heavy ion collisions. Till now to debate is also on. Similarly, strange baryons (both single and multi strange hyperons),,, are important in the context of heavy ion collisions. Here we study for strange hyperons (single strangeness) including mesons using momentum integrated Boltzmann equation, also with a plan to study the multi strange baryons. We start with the strange quark production in a quark gluon scenario, which under go hadronization to form strange hadrons.

4 Experiments AGS RHIC SPS Experiments Ebeam (A GeV) snn (GeV) System Particles AGS E80, E866, E877, E891, E895, E Au+Au, K, p, SPS NA45, NA49, NA57, (NA44, WA98) Pb+Pb, K, p,,,,,... RHIC STAR, PHENIX, BRAHMS, PHOBOS Au+Au, K, p,,,,,... LHC ALICE 760,7000 Pb+Pb K,π,φ,Σ,Λ,Ω, Ρ, Fakir Mohan University,Balasore

5 DAE-HEP IIT Guwahati, Processes of Strange productions in quark gluon medium Two main processes those produce strange quarks are: gg s s qq s s Gluon gluon fusion Quark and anti-quark annihilation Fakir Mohan University,Balasore

6 DAE-HEP IIT Guwahati, Cross-sections for those channels are calculated up to lowest order QCD Where, s p1 p Where s is the strong coupling constant. m is the mass of strange quark, taken to be 150 MeV. Fakir Mohan University,Balasore

7 DAE-HEP IIT Guwahati, 014 Strangeness Production in Hadronic Scenario In hadronic scenario we have all mesons and baryons. The interaction of these mesons and baryons produces strange mesons and baryons. The interaction processes can be categorized in to three types as; (i) Meson-meson (ii) Meson-baryon (iii) Baryon-baryon interactions MM K K MB YK G. E. Brown, C. M. Ko, Z. G. Wu & L. H. Xia, PRC 43 (1991) 1881 BB BYK For strange meson, we considered the production of K-mesons (K+, K-, K0 and K0 bar) For strange baryons, we have considered the production of Λ and Σ Fakir Mohan University,Balasore

8 DAE-HEP IIT Guwahati, 014 MM K K For meson-meson interaction processes we have taken four channels G. E. Brown, C. M. Ko, Z. G. Wu & L. H. Xia, PRC 43 (1991) MM K K The Lagrangian describing the above processes are LK *K g K *K K * K K L KK g KK K K K K 1 p' 3 sp 1 Isospin averaged cross 1 dx M ( s, x) section where s is the square of total centre of mass energy, p & p are 3-momenta of incoming meson & kaon in c.m. frame. M(s,x) is the isospin-averaged squared invariant amplitude. Strange production in different scenarios. Fakir Mohan University,Balasore

9 Strange Hyperon productions from meson and baryon interactions have Been considered in following four channels,. MB YK Isospin averaged cross-section N K Ji 1 i ( s1 1)( s 1) B in i B out i i ki s1 mi i / 4 J =spin of the resonances Play important role in FAIR energies (s+1)=polarization states of incident particle Bin and Bout =branching ratios of the initial- and final-state chhanels Fakir Mohan University,Balasore

10 Strange Hyperon productions from baryon and baryon interactions have been considered in following four channels 3. BB BYK and others These play an important role in very low colliding energies when the baryon density is quite high Isospin averaged cross section NN N K n 3m p s Wmax q f q NN dw W k dq F q W ; q 0 m ( q m ) Wmin q A Fakir Mohan University,Balasore 10

11 Isospin averaged cross section NN N K n 3m p s Wmax q f NN q dw W k dq F q W ; q 0 m ( q m ) Wmin q Wmin mk m Wmax s1 mn q mn E E ' p p ' while E p mn 1 & p are the energy & momentum of nucleon N1 in the c.m. system while E' & p' are those of N 3. m F ; is the cut off parameter 1 GeV. q Fakir Mohan University,Balasore 11

12 Rate of production for two particle going to two particle a1 p1 a p a3 p1' a4 p', where a1 a d 3 p1 d 3 p R (T ) F ( p1 ) F ( p ) vrel ( M ) 3 3 Where, F ( p) exp[ ( E ) T ], M E p vrel v1 v, Fakir Mohan University,Balasore

13 Rate of production of strange quark at SPS energy

14 DAE-HEP IIT Guwahati,014 Rate of production of strange quarks at LHC energy Strange quarks Fakir Mohan University,Balasore 14

15 DAE-HEP IIT Guwahati,014 Rate of Lamda and Sigma production at AGS and SPS energy Fakir Mohan University,Balasore 15

16 DAE-HEP IIIT Guwahati,014 Rate of Lamda and Sigma production at RHIC energy Rate of Lamda and Sigma production at LHC energy Fakir Mohan University,Balasore 16

17 Evolution of Strangeness It is assumed that non-strange quarks and hadron Momentum integrated Boltzman equation is used Partonic phase These equations have to be solved along with temperature evolution and chemical potential evolution equations simultaneously.

18 Hadronic phase phase

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20 Temperature evolution in quark gluon matter

21 Chemical potential evolution in quark gluon matter Baryon chemical potential evolution

22 Strange chemical potential evolution n s i i 0, Assuming V same for all species i We look for which s satisfies the above criteria. Net chemical potential evolution in quark gluon matter, becomes

23 Chemical potential evolution in Hadronic matter Baryon chemical potential evolution Net density in the system Evolution of baryon chemical reduces to equation reduces to

24 Similarly we get the strangeness evolution equation from following conservation equation Finally we solve all the coupled differential equations to get the strange mesons and baryons

25 Summary The boltzmann equation has been used to study the evolution of s and sbar in the partonic phase and Λ and Σ in the hadronic phase. The rate of production of strange quark with temperature in energy range 8.1GeV &.76Tev has been calculated. The rate of production of strange hyperon(λ & Σ) with temperature for energy range AGS to LHC has been calculated.

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27 Rate of production of strange quark at SPS energy

28 DAE-HEP IIT Guwahati,014 Rate of production of strange quarks at LHC energy Strange quarks Fakir Mohan University,Balasore 8

29 Strange hyperon Strangeness -1 -(multistrange) Lamda ( ) =(uds) Cascade( );- =() = Sigma(Σ); Σ =(uus) +1 Σ =(dds) Σ =(uds) Omega( ); Ω = (sss) -3(multistrange) Why strange? Having strange quantum number.

30 Results; It is observed that for c.m.energy.76 Tev the process of Gluon fusion dominates over the qq annihilationfor the entire temperature range. FUTURE WORK; Study the rate of production of multi satrange hyperon for different c.m energy using momentum integrated Boltzmann transport equation. Study the strange and multistrange particle at FAIR energies.