BB 22 pairs in e+e- Andrzej Kupsc, Uppsala. Time-like elastic (and transition) Form Factors. J/ψ and ψ(2s) decays to B 1 B 2.

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1 Production of BB 11 BB 22 pairs in e+e- Andrzej Kupsc, Uppsala Time-like elastic (and transition) Form Factors J/ψ and ψ(2s) decays to B 1 B 2 Spin polarization Hyperons from J/ψ and ψ(2s): decay parameters and CP tests Prospects for Super tau-charm factory (vs BelleII, PANDA) HIEPA,

2 Baryon Electromagnetic Form Factors γ*bb vertex functions Form Factors (FFs) Baryon with spin s 2s+1 FFs Functions of photon virtuality q 2 Distribution of charge + magnetization radius is related to FFs slope at q 2 =0 Connect to distribution, dynamics of quarks in hadrons Considered to be well understood for nucleons (space-like) Unexpected results + old paradigms falsified: Proton radius puzzle New type of experiments High statistics and precision arxiv:

3 Baryon Electromagnetic Form Factors qq 2 [GeV 2 /c 4 ] γ* BB 11 BB 22 BB 11 BB 22 e+e- pp pp e+e- pp pp π 0 e+e- spacelike q 2 <0 elastic: B 2 =B 1 (B 2 B 1 transition) timelike q 2 >0

4 ee + ee γγ BB 11 BB 22 Spin one-half baryon FFs Polarization of baryons: Dubnickova, Dubnicka, Rekalo Nuovo Cim. A109 (1996) 241 Gakh, Tomasi-Gustafsson Nucl.Phys. A771 (2006) 169 Czyz, Grzelinska, Kuhn PRD75 (2007) Fäldt EPJ A51 (2015) 74; EPJ A52 (2016)141

5 Nucleon anti-nucleon cross sections ee + ee nn nn ee + ee pppp SCAN+ISR R is given by the angular distribution at fixed q 2

6 e+e annihilation into baryon-antibaryon pairs J. G. Körner and M. Kuroda Phys. Rev. D 16,

7 ee + ee γγ ΛΛ ΛΛ Enhancement at threshold for Λ... Phys.Rev. D97 (2018)

8 ee + ee γγ ΛΛ cc ΛΛ cc BESIII arxiv: >PRL

9 Baryon FFs: (elastic and transition FFs) = VV Baryons BB 1 and BB 2 (spin 1/2, 3/2,...) vs J/ψ decay: VV = ρρ, ωω, φφ,, JJ/ψψ, ψψ(2s),

10 Baryon FFs: (elastic and transition FFs) = VV Baryons BB 1 and BB 2 (spin 1/2, 3/2,...) vs J/ψ decay: VV = ρρ, ωω, φφ,, JJ/ψψ, ψψ(2s),

11 JJ/ψψ, ψψ(2222) BB BB Phys. Rev. D 93, (2016) PLB770(2017)217 Phys. Rev. D 95, (2017) With (1.31)x10 9 J/ψ and (4.48)x10 8 ψ(2s)

12 ee + ee γγ JJ/ψψ ΛΛ ΛΛ α ψ =0.469+/ BF=(19.43+/-0.03) 10-4 BESIII,PRD 95, (2017) Process also described by two Form Factors (two complex numbers) i.e. three real parameters: BF,α ψ and phase ΔΦ

13 Baryon polarization in e+e- yy PP Λ ee + Λ θθ Λ zz For unpolarized e+e- beams Λ ee PP Λ ΔΦ 0 cos θθ Λ αα ψψ = ΔΦ = ππ 2

14 ee + ee ΛΛ ppππ ΛΛ pp θθ pp nn yy ee + Λ θθ Λ cos θθ pp nn = sin θθ 1 sin φφ 1 zz 1 + αα PP Λ cos θθ pp nn Λ ee Λ ppπ : Ω 1 = (cos θθ 1, φφ 1 ) αα Hyperon polarization determined using angular distribution of the baryon from weak decay

15 Exclusive decay distributions ee + ee (Λ ppπ )( Λ ppπ + ) ee + ee (Λ ppπ )( Λ nnπ 0 ) ξξ (cos θθ Λ, Ω 1, Ω 2 ) Λ ppπ : Ω 1 = (cos θθ 1, φφ 1 ) αα 1 α Λ ppπ + (oooo nnπ 0 ): Ω 2 = (cos θθ 2, φφ 2 ) Λ nnππ 0 : αα 2 αα 0 Λ ppππ + : αα 2 αα + Fäldt, Kupsc PLB772 (2017) 16

16 General two spin ½ particle state 16 parameters for each θ: I(θ), polarizations (6) Spin correlations (9) polarizations (6) Spin correlations (9) moments: (uncorrected for acceptance)

17 ee + ee (Λ ppπ )( Λ ppπ + ) ee + ee (Λ ppπ )( Λ nnπ 0 ) events events 399 background 66 background Global unbinned maximum log likelihood fit to the two data sets with the likelihood function constructed from probability function: Where is the normalization factor obtained from weighted sum for flat phase space model MC events after detector reconstruction.

18 Fit results ee + ee (Λ ppπ )( Λ ΔΦ=42.3 o ±0.6 o ±0.5 o ppπ + ) ee + ee (Λ ppπ )( Λ nnπ 0 ) CP asymmetry: AA CCCC = αα + αα + αα αα +

19 Λ ppππ : αα αα prel 17% larger than PDG avg > 5 σ difference CP test ΔΦ=42.3 o ±0.6 o ±0.5 o αα AA CCCC = αα + αα + αα αα + A CP = ± 0.012± Polarization: max 25% A CP = ± PS185 PRC54(96)1877 CKM A CP 10-4

20 Prospects for other hyperons What if phase is non-zero also for other J/ψ or ψ(2s) decays into hyperon antihyperon? measure simultaneously for two body weak decays α and αα and test CP: A CP =(α + αα)/(α - αα) For cascades: Ξ - Ξ + Λπ - Λπ + pπ - π - pπ + π + could also measure ϕ Ξ -, ϕ Ξ + and do more (10x) sensitive CP test: B CP = (β Ξ - + β Ξ +)/(β Ξ - - β Ξ +)... or if there is a way to measure pp and pp polarization also ϕ Λ... PDG

21 Nuclear Physics News, Vol. 27, No. 3, 2017

22 ee + ee γ JJ/ψ Λ Λ GeV/c ev GeV/c ev α ψ =0.469+/ BR(19.43+/-0.03)10-4 PRD 95, (2017) P max =25% PS185, PRC54 (1996) parameters at each θ Λ Can t determine Λ decay param. 2 global parameters extract Λ decay par. α

23 Conclusions: Prospects for ee + ee BB 11 BB 22 at Super tau-charm factory Scan competitive if search for narrow structures (other BelleII + ISR?) Beam Polarization for FFs (phase between FFs) [proton polarimeter??] Entangled (and polarized?) B 1 B 2 pairs from J/ψ and ψ(2s) for CP tests and hyperon decay parameters

24 Conclusions: Prospects for ee + ee BB 11 BB 22 at Super tau-charm factory Scan competitive if search for narrow structures (other BelleII + ISR?) Beam Polarization for FFs (phase between FFs) [proton polarimeter??] Entangled (and polarized?) B 1 B 2 pairs from J/ψ and ψ(2s) for CP tests and hyperon decay parameters Thank you!