Thermodynamic Signatures of Additional Strange and Charm Baryons

Transcription

1 Thermodynamic Signatures of Additional Strange and Charm Baryons Swagato Mukherjee April 2015, GHP, Baltimore, MD

2 Heavy-ion collisions: a sketch Time initial state QGP, hydro. expansion Tc, μ c freeze-out s pre-equilibrium hadronization T f, μ Bf Temperature detectors: hadrons freeze-out stage ''observed'' in HIC 2

3 Hadrons yields at the freeze-out well described by: Hadron Resonance Gas (HRG) thermal gas of uncorrelated hadrons with vacuum masses ^ f (m ^ h ) cosh [Bh μ^ B +Qh μ^ Q +Sh μ^ S +Ch μ^ C ] P h thermal abundance of hadrons compare with expt. hadron yields = P tot all hadrons P h hat dimensionless in T units freeze-out parameters f f f f ( T, μb, μq, μ S ) thermal conditions ''observed'' in HIC 3 Andornic et.al.: Nucl. Phys. A904, 535c (2013)

4 LQCD: validity of hadronic description baryon charge/strangeness/charm correlations: χ ^ h ) cosh [Bh μ^ B + Qh μ^ Q +Sh μ^ S +Ch μ^ C ] HRG: P^ h f ( m nm BX χ /χ km BX n k =B nm BX n+m ^ P = n m μ^ B μ^ X μ =0 n χ nm = B F ( m) BX = 1, when dof are hadronic with B=1 < 1, when dof are quarks with B=1/3 independent of hadron mass spectrum, relies only on changing quantum number uncorrelated hadron gas description is valid right till the QCD crossover region chiral crossover: T c = 154±9 MeV 4

5 LQCD: validity of hadronic description baryon charge/strangeness/charm correlations: χ ^ h ) cosh [Bh μ^ B + Qh μ^ Q +Sh μ^ S +Ch μ^ C ] HRG: P^ h f ( m nm BX χ /χ km BX n k =B nm BX n+m P = n m μ B μ X μ =0 n χ nm = B F ( m) BX = 1, when dof are hadronic with B=1 < 1, when dof are quarks with B=1/3 independent of hadron mass spectrum, relies only on changing quantum number uncorrelated hadron gas description is valid right till the QCD crossover region chiral crossover: T c = 154±9 MeV 5

6 Probing hadron spectrum using thermodynamics hadronic pressure: PC = h all hadrons Quark Model Ph expt. observed hadrons + unobserved ones charm baryons Ebert et. al.: Eur. Phys. J. C66, 197 (2010); Phys. Rev. D84, (2011) 6

7 Probing hadron spectrum using thermodynamics hadronic pressure: PC = h all hadrons Quark Model expt. observed hadrons + unobserved ones Ph charm baryons LQCD Padmanath et.al.: arxiv: [hep-lat] Ebert et. al.: Eur. Phys. J. C66, 197 (2010); Phys. Rev. D84, (2011) 7

8 Probing hadron spectrum using thermodynamics hadronic pressure: PS = h all hadrons Quark Model Ph expt. observed hadrons + unobserved ones strange baryons Capstick-Isgur: Phys. Rev. D34, 2809 (1986) 8

9 Probing hadron spectrum using thermodynamics hadronic pressure: PS = h all hadrons Quark Model expt. observed hadrons + unobserved ones Ph strange baryons LQCD JLab: Phys. Rev. D87, (2013) Capstick-Isgur: Phys. Rev. D34, 2809 (1986) 9

10 Probing hadron spectrum using thermodynamics strange sector charm sector partial pressure of baryon B; meson M similar results with LQCD spectra significant contributions of these unseen states to the ratios of partial pressures of baryon to meson near the QCD crossover LQCD: operators to identify separate thermodynamic contributions of strange/charm baryons/mesons 10

11 Operators for partial pressures of baryons & mesons suitable combinations of up to 4th order baryon charm/strangeness correlations χ nm BX ^ n+m P = n μ^ B m μ^ X μ =0 BNL-Bi: Phys. Lett. B737 (2014) 210; Phys. Rev. Lett. 111, (2013) a simplified example: ^ C PC cosh[ μ^ ] + PC cosh [ μ^ +μ^ ] hadron gas P M C B B C partial pressure of C =1 mesons χ Ck PCM + PCB partial pressure of C =1 baryons neglect contributions of heavier C =2,3 baryons, x1000 suppressed C χ BC P mn B 11

12 Signatures of additional charm baryons relative contributions: charm baryons to charmed mesons C BC C C χ BC /(χ χ )=P /P B M charged charm baryons to charged charmed mesons strange charm baryons to strange charmed mesons BNL-Bi: Phys. Lett. B737 (2014) 210 signatures of additional, yet unobserved charm baryons from QCD thermodynamics 12

13 Thermodynamic contributions of additional strange baryons relative contributions of strange baryons to strange mesons S χ BS (T )/ χ 11 2 (T) BNL-Bi: Phys. Rev. Lett. 113 (2014) partial pressure of strange mesons: S S BS M1 = χ 2 χ 22 1 S 1 BS MS2 = χ χ S2 ) + ( χbs + χ ( 13 ) partial pressure of strange baryons: 1 BS BS 11 χ BS + 6 χ + χ ( ) 6 1 S 1 BS BS2 = χ 4 χ S2 ) + ( 4 χ BS χ ( ) 12 3 BS1 = + undiscovered strange baryons contributions of all expt. observed strange hadrons 13

14 Thermodynamic contributions of additional strange baryons relative contributions of S=1 baryons to strange mesons relative contributions of S=3 baryons to strange mesons 14

15 Hierarchical freeze-out of light & strange hadrons? Andornic et.al.: Nucl. Phys. A904, 535c (2013) ~10-5 MeV systematic difference in freeze-out T from separate fits to light and strange hadrons two separate freeze-out stages for light and strange hadrons? Phys. Rev. Lett. 111, (2013); Phys. Lett. B727, 554 (2013); Europhys. Lett. 104, (2013)... 15

16 Strange baryon yields in heavy-ion collisions [ ( 1 Ξ /Ξ Ω /Ω 2 μbf n Λ nξ nω,, = exp f n Λ nξ n Ω T Λ / Λ [ ] nb ln nb μsf μ f B )] S does not assume spectrum of hadron gas, only assumes hadron yields are thermal f f slope ~ μ S /μ B S 16

17 Strangeness neutrality & strangeness chemical potential medium formed in HIC is strangeness neutral: ns =0 μs χ BS 11 (T) +... μ B (T, μ B / T) S χ 2 (T) relative contribution of strange baryons to mesons LQCD results are reproduced by including additional Quark Model states a given value of μs /μ B is realized at a lower temperature BNL-Bi: Phys. Rev. Lett. 113 (2014)

18 Strangeness, LQCD and freeze-out in HIC freeze-out T by comparing μs /μ B from LQCD and expt. not reproduced by strangeness neutral hadrons gas with only PDG states BNL-Bi: Phys. Rev. Lett. 113 (2014)

19 Additional strange hadrons & freeze-out in HIC inclusion of additional strange hadrons reduces freeze-out T & agrees with LQCD+expt. determination indirect evidence for so-far undiscovered strange baryons at RHIC? BNL-Bi: Phys. Rev. Lett. 113 (2014)

20 Additional strange hadrons & RHIC BES signature for unobserved strange baryons persists for RHIC BES-II can also be extracted from expt. measured ln [ NK / NK + ln [ Np / Np ] ] = μ Sf f μb need accurate expt. measurements & feed-down corrections 20

21 Summary hot-dense LQCD: additional, yet unobserved strange & charm baryons become thermodynamically relevant near the QCD crossover these additional strange baryons are important for determining the `observed' freeze-out temperatures of heavy-ion collision experiments freeze-out temperatures for strange hadrons obtained comparing LQCD and HIC expt. favors presence of these additional hadrons 21