Search for Deeply-bound K-pp States in 3 He(K - , Λp )n Reaction -Recent Results from J-PARC E15 Experiment H. Outa for E15 collaboration 1 MIN16 - Meson in Nucleus 2016, 31 Jul - 2 Aug 1
Hadron masses and χ - symmetry Objectives - Can kaon be a member of nuclei? - Kaon properties change in nuclear media? Key questions : - Kaon condensation in neutron star ? ? χ -condensate S - n attractive fraction S - n repulsive ρ
Search for Kaonic nuclear states assuming Λ(1405) = K - p bound state … T. Yamazaki & Y. Akaishi, PLB 535 (2002) 70 strongly attractive in I=0 channel nuclear state search K - pp • simplest system 3 He(K - , n) @ 1 GeV/ c formation of high density matter?
P resent “ Kpp" Candidates @ B K ~100 MeV very deep ?? M(Σ+π+p) M(K+p+p) J-PARK E27 DISTO Many objections exist, though… why no threshold ( Σπp ) effect seen? why no quasi-elastic K seen? p+p → p+N + (1710) → p+ (Λ +K + ) … 4
Situation of 𝑳 − 𝒒𝒒 bound state ► Theoretical calc. Bound state exists KbarN interaction model E-dep. / E-indep. E-indep. ► Experiments Reports structure / NO structure E-dep. J-PARC E27 LEPS 𝑒 𝜌 + , 𝐿 + 𝑌 𝑞 𝛿, 𝜌 − 𝐿 + 𝑌 DISTO HADES 𝑞𝑞 → Λ𝑞𝐿 + 𝑞𝑞 → Λ𝑞𝐿 + FINUDA (𝑡𝑢𝑝𝑞𝑞𝑓𝑒 𝐿 − , Λ𝑞) T. Yamaga
analyzed only kinematically but with well-identified FS
Published E15 1st data Only 3 days! (suspended by the earthquake) 3 He(K - , n) — semi-inclusive 3 He(K - , Λp) n — exclusive with new data! 7
E15 3 He(K - ,n)X DATA MC 1/ b distribution for g /n
Improving statistics via E15 2nd data What is the structure found in E15 1st data? E15 1st E15 2nd 3 days → 3 weeks w/ higher priority to Λp in CDS ~ 6 times more data for forward neutron M Λp → ~ 30 times more data for Λpn final state
E15 1st and E15 2nd spectra consistent? PTEP(2016) fit w/ “single” peak B(X) ~ 15 MeV Γ( X) ~ 110 MeV Q(X) ~ 400 MeV/c M Λp → 10
E15 1st and E15 2nd spectra consistent? YES! They are consistent! M Λp → 11
E15 1st and E15 2nd spectra consistent? YES! They are consistent! E15 2nd spectrum does not allow single pole assumption M Λp → 12
MENU2016@Kyoto kinematical limit K - pp formation CM flat for point-like 3NA Is 3 He point-like? 2NA process p s with spectator n s / p s n s Kinematical Limit 13 T. Yamaga
MENU2016@Kyoto structure(s?) Λp invariant mass M Λp → 2NA K - +“pp+n s ”→Λp+n s 14 T. Yamaga
3 He(K - , Λp )n: Angular Dependence of n in CM
3 He(K - , Λp)n: Angular Dependence forward n only q Λp → M Λp → distribute uniformly over Dalitz ~ “point like reaction?”
3 He(K - , Λp)n: Angular Dependence of n in CM two components exist? if that is the case, bound region : forward unbound region : peaking very forward peaking bit strongly depend to cosθ weakly depend to cosθ lower Q K preferred
3 He(K - , Λp)n: Not like semi-inclusive spectrum, “quasi - free K” excluded by the final state: Λ pn, but still need to ask … through uncorrelated Λ(1405) p channel Sekihara Oset Ramos
Sekihara’s calculation with QF-K and K-pp explains well the E15 cosθ cm distributions But…
3 He(K - , Λp)n: flat dist. assuming uncorrelated Λ*p flat dist. channel do not interfere with flat dist.
3 He(K - , Λp )n: comparison forward n only arXiv:1607.02058v1 [hep-ph] 7 Jul 2016 QE + “Kpp” K multiple scattering
3 He(K - , Λp )n: comparison forward n only arXiv:1607.02058v1 [hep-ph] 7 Jul 2016 QE + “ Kpp ” K multiple scattering
Recent results ► Theoretical calc. ► Experiments KN interaction model Reports structure / NO structure E-dep. / E-indep. with single pole assumption J-PARC E15 1 st E-indep. 3 He(K - , Λp )n: ?? could be the first convincing data J-PARC E15 2 nd … after a long journey … E-dep. with double structures T. Yamaga
THANKS
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