Properties of the Λ(1405) Measured at CLAS

Transcription

1 PANIC 11 Properties of the Λ(145) Measured at CLAS Kei Moriya (Indiana University) advisor: Reinhard Schumacher (Carnegie Mellon University) July 5, 11

2 Outline 1 Introduction What is the Λ(145)? Chiral Unitary Theory of the Λ(145) CLAS Analysis Introduction to JLab and CLAS Decay Channels of Interest Σ (1385) and K Background Fit to Extract Λ(145) Lineshape 3 Results Λ(145) Lineshape Results Λ(145) Cross Section Results Λ(15) Cross Section Results Λ(145)/Λ(15)/Σ(1385) Cross Section Comparison 4 Conclusion K. Moriya (IU) Λ(145) lineshape July 11 / 4

3 What is the Λ(145)? **** resonance just below NK threshold ( 1435 MeV) I(J P ) = ( 1 ) [experimentally unconfirmed until now] Decays exclusively to (Σπ) Past experiments have found the lineshape (= invariant Σπ mass distribution) is distorted from a simple Breit-Wigner form Main Question: What is the nature of this distorted lineshape? K. Moriya (IU) Λ(145) lineshape July 11 3 / 4

4 The Λ(145) in Hadron Spectroscopy. 167 Σ(167) Σ(166) 15 Λ(15) cannot decay to NK 1435 N Kthreshold Λ(145) Σ(1385) Mass(MeV) Σ Λ I = I =1 K. Moriya (IU) Λ(145) lineshape July 11 4 / 4

5 The Λ(145) in Hadron Spectroscopy Σ(167) 167 Σ(166) 15strongNΛ(15) Kattraction. cannot decay to NK 1435 N Kthreshold Λ(145) Σ(1385) Mass(MeV) Σ Λ I = I =1 K. Moriya (IU) Λ(145) lineshape July 11 4 / 4

6 The Λ(145) in Hadron Spectroscopy Σ(167) 167 Σ(166) 15strongNΛ(15) Kattraction Mass(MeV) Λ(145) N Kthreshold strong dynamics due to Σπ and N K interaction cannot decay to NK Σ(1385) Σ Λ I = I =1 K. Moriya (IU) Λ(145) lineshape July 11 4 / 4.

7 The Lineshape of the Λ(145) Several theories exist on the nature of the distorted lineshape All theories agree that there is a strong coupling between the Σπ channel (below NK threshold) NK channel (above NK threshold) Various theories: normal qqq-baryon resonance (the constituent quark model has difficulty with Λ(145) mass) unstable bound state of NK (promoted by Dalitz and others) qqqqq dynamically generated resonance in unitary coupled channel approach K. Moriya (IU) Λ(145) lineshape July 11 5 / 4

8 Coupled Channel Chiral Unitary Model Chiral Theory Effective chiral Lagrangian describes the interactions of the ground state baryons and mesons. Coupled Channels Exact unitarity is enforced amongst the coupled channels Many predictions on hadrons have been given by E. Oset, D. Jido, W. Weise and others K. Moriya (IU) Λ(145) lineshape July 11 6 / 4

9 J.C. Nacher et al.rphysics Letters B 455 ( 1999) Chiral Unitary Coupled Channel Approach equation, and diagrammatically g.. t in Fig. is easily evaluated. The process dynamically with thegenerate j channel Λ(145) in the bybased meanson of the chiral vector unitary D scmodel P q. e ž j Ý l l l j/ j 1 j D q D G T, Ž 8. l Chiral Unitary Model Prediction! factorization of the strong ampliwx for! the "! related electro- q Fig.. DiagrammaticLineshape representationof of #(145) the meson-baryon final nd in % p & state K " " interaction! in thepredicted g p K LŽ 145 to. depend process. on "! as been used. Diagrams where the decay channel E ' 1.7 GeV % the mesons or baryons inside the! J. C. Nacher, E. Oset, H. uppressed at threshold. One can Toki, A. Ramos, Phys. Lett. B ution from the photon attached to Ž.! " the built up of the 455, L (1999). resonance, most of them exactly at threshold. This can be open!! " " up at higher energies and the resonance shape! Chiral t the loop involves a term of the is only visible in the p q S y Lagrangian, p y S q, p S mb FSI channels. Channel Coupling fž q,q., with fž q,q. L L a scalar The KN production occurs at energies slightly above! I("!) ral is proportional to q and vanulomb gauge constraint, epqs. provides a small background below the resonance. the resonance and the p = {,1,} not in an L, with isospin one, only isospin eigenstate ll values of the K q!!" momentum Invariant Mass (GeV) It is interesting to I= see contributions the different shapes negligible J. C. Nacher et al., Phys. Lett. B455, 55 (1999) of the! the corrections to the cross sec- three ps channels. This Interference can be understood between ini= "! terms d$/dm I (µb/gev) K. Moriya (IU) Λ(145) lineshape July 11 7 / 4

10 I ( ) 1 Difference in Lineshapes!" Invariant Mass (GeV) $ # d( "! ) 1 1 ) T $ T $ Re T T $ O T dm 3 6 I & ' & ' (1) () () (1)* () # $ d(" (! ) 1 1 ) T $ T # Re T T $ O T dm 3 6 & ' & ' (1) () () (1)* () d("! ) T $ O& T dm 3 I () () '! P7"!<R #3-34#( /! PRT1-()! P()/$5/ %(.PR8 I%33.#3 J. C. Nacher et al., Nucl. Phys. B455, 55 Difference in lineshapes is due to interference of isospin terms in calculation (T (I) represents amplitude of isospin I term) This analysis will measure all three Σπ channels K. Moriya (IU) Λ(145) lineshape July 11 8 / 4

11 counts o 6 Summary of Current Experimental Status Data is sparse All experiments show a distortion from a Breit-Wigner more data is needed [1,, r q i i /i 8o/\ /i ibl,/["~, )\ /_J/l\ i I\ k 4, I I I )4J5 15 M(Σ, π)[mev] D. W. Thomas et al., Nucl. Phys. B56, 15 (1973) Moss of Z ~ "n:~ (MeV/c ) K. Moriya (IU) Λ(145) lineshape July 11 9 / 4

12 Summary of Current Experimental Status Data is sparse All experiments show a distortion from a Breit-Wigner more data is needed I I I 4 counts o 16 % 1 oj I: Srei -Wig, ti~.~ K- Matrix Fit 4 7t 'l "O e- o, I./, I./,5 M(Σ, π)[gev] R. J. Hemingway, Nucl. Phys. B53, 74 (1985) K. Moriya (IU) Λ(145) lineshape July 11 9 / 4

13 Summary of Current Experimental Status Data is sparse All experiments show a distortion from a Breit-Wigner more data is needed )] σ/d(cosθ)dm [µ b/(.1 GeV/c (a) 1.5 < E γ <. GeV )] σ/d(cosθ)dm [µ b/(.1 GeV/c (b). < E γ <.4 GeV d M(Σ, MM(K π)[gev] ) (GeV/c ) d M(Σ, MM(K ) π)[gev] (GeV/c ) M. Niiyama et al., Phys. Rev. C78, 35 (8) K. Moriya (IU) Λ(145) lineshape July 11 9 / 4

14 Outline 1 Introduction What is the Λ(145)? Chiral Unitary Theory of the Λ(145) CLAS Analysis Introduction to JLab and CLAS Decay Channels of Interest Σ (1385) and K Background Fit to Extract Λ(145) Lineshape 3 Results Λ(145) Lineshape Results Λ(145) Cross Section Results Λ(15) Cross Section Results Λ(145)/Λ(15)/Σ(1385) Cross Section Comparison 4 Conclusion K. Moriya (IU) Λ(145) lineshape July 11 1 / 4

15 JLab and CLAS Jefferson Lab (JLab) located in Newport News, VA CEBAF (Continuous Electron Beam Accelerator Facility) gives ns timing electron beam up to 6 GeV Halls A, B, C ( D: upcoming) Hall B = CLAS (CEBAF Large Acceptance Spectrometer) collaboration K. Moriya (IU) Λ(145) lineshape July / 4

16 Data From Lab liquid LH target γ p K Λ(145) K. Moriya (IU) Λ(145) lineshape July 11 1 / 4

17 Data From Lab liquid LH target γ p K Λ(145) real unpolarized photon beam E γ < 3.84 GeV B total triggers K. Moriya (IU) Λ(145) lineshape July 11 1 / 4

18 Data From Lab liquid LH target γ p K Λ(145) real unpolarized photon beam E γ < 3.84 GeV B total triggers measure charged particle p with drift chambers K. Moriya (IU) Λ(145) lineshape July 11 1 / 4

19 Data From Lab liquid LH target γ p K Λ(145) real unpolarized photon beam E γ < 3.84 GeV B total triggers measure charged particle p with drift chambers timing with TOF walls K. Moriya (IU) Λ(145) lineshape July 11 1 / 4

20 Reaction of Interest γ p K Λ(145) K Σ π Final state of interest is K, Σ, π Σπ resonances: Σ(1385), Λ(145), Λ(15) K π resonance: K when π = π or π besides the K Σπ state, we will also detect the K Λπ state Resonance of Λπ will be Σ(1385) Resonance of K π will be K Background channels: Σ(1385) close in mass, large width ( 35 MeV) K overlap in 3-body phase space plot of K, Σ, π K. Moriya (IU) Λ(145) lineshape July / 4

21 - Background Channels Σ (1385) Σπ BR(Λπ ) = 87% BR(Σ ± π ) = 6% each measure in Λπ, scale down to each Σπ channel influence should be small due to branching ratio K Σ broad width will overlap with signal subtract off incoherently low energy bin ),π M(Σ kinematic boundary Λ(15) * K Wbin: 3.15 <W<.5 data kfit Σ only: Λ(145) M(K,π ) K. Moriya (IU) Λ(145) lineshape July / 4-1 1

22 - Background Channels Σ (1385) Σπ BR(Λπ ) = 87% BR(Σ ± π ) = 6% each measure in Λπ, scale down to each Σπ channel influence should be small due to branching ratio K Σ broad width will overlap with signal subtract off incoherently high energy bin ),π M(Σ. 1.8 * K kinematic boundary Wbin: 8.65 <W<.75 data kfit Σ only: Λ(15) Λ(145) M(K,π ) K. Moriya (IU) Λ(145) lineshape July / 4

23 Σ(1385) is Fit in Λπ Channel (γ p K p π π ) counts Wbin: anglebin: Λ π threshold.5 <W<.15 CM.7<cosθ K <.8 data example: 1 energy and angle bin out of M(Λ π ) Σ(1385) is fit with templates of MC of Σ(1385) (non-relativistic Breit-Wigner) K Λ MC very good fit results K. Moriya (IU) Λ(145) lineshape July / 4

24 Σ(1385) is Fit in Λπ Channel (γ p K p π π ) counts Wbin: anglebin: Λ π threshold.5 <W<.15 CM.7<cosθ K <.8 data Σ(1385) MC example: 1 energy and angle bin out of M(Λ π ) Σ(1385) is fit with templates of MC of Σ(1385) (non-relativistic Breit-Wigner) K Λ MC very good fit results K. Moriya (IU) Λ(145) lineshape July / 4

25 Σ(1385) is Fit in Λπ Channel (γ p K p π π ) counts Wbin: anglebin: Λ π threshold.5 <W<.15 CM.7<cosθ K <.8 data Σ(1385) MC * K Λ MC example: 1 energy and angle bin out of M(Λ π ) Σ(1385) is fit with templates of MC of Σ(1385) (non-relativistic Breit-Wigner) K Λ MC very good fit results K. Moriya (IU) Λ(145) lineshape July / 4

26 Σ(1385) is Fit in Λπ Channel (γ p K p π π ) counts Wbin: anglebin: Λ π threshold.5 <W<.15 CM.7<cosθ K <.8 data Σ(1385) MC * K Λ MC sum of MC χ /ndf: 1.6 example: 1 energy and angle bin out of M(Λ π ) Σ(1385) is fit with templates of MC of Σ(1385) (non-relativistic Breit-Wigner) K Λ MC very good fit results K. Moriya (IU) Λ(145) lineshape July / 4

27 Fit to Lineshape With MC Templates Σ p π Wbin: 3 anglebin: <W<.5 CM.7<cosθ K <.8 data counts 3 example: 1 energy and angle bin out of Σ π Invariant Mass (GeV) subtract off Σ(1385), Λ(15), K assigned the remaining contribution to the Λ(145) K. Moriya (IU) Λ(145) lineshape July / 4

28 Fit to Lineshape With MC Templates counts Σ p π Wbin: 3 anglebin: <W<.5 CM.7<cosθ K <.8 data Σ(1385) MC example: 1 energy and angle bin out of Σ π Invariant Mass (GeV) subtract off Σ(1385), Λ(15), K assigned the remaining contribution to the Λ(145) K. Moriya (IU) Λ(145) lineshape July / 4

29 Fit to Lineshape With MC Templates counts Σ p π Wbin: 3 anglebin: <W<.5 CM.7<cosθ K <.8 data Σ(1385) MC Λ(145) MC ver.1 example: 1 energy and angle bin out of Σ π Invariant Mass (GeV) subtract off Σ(1385), Λ(15), K assigned the remaining contribution to the Λ(145) K. Moriya (IU) Λ(145) lineshape July / 4

30 Fit to Lineshape With MC Templates counts Σ p π Wbin: 3 anglebin: <W<.5 CM.7<cosθ K <.8 data Σ(1385) MC Λ(145) MC ver.1 Λ(15) MC example: 1 energy and angle bin out of Σ π Invariant Mass (GeV) subtract off Σ(1385), Λ(15), K assigned the remaining contribution to the Λ(145) K. Moriya (IU) Λ(145) lineshape July / 4

31 Fit to Lineshape With MC Templates counts Σ p π Wbin: 3 anglebin: <W<.5 CM.7<cosθ K <.8 data Σ(1385) MC Λ(145) MC ver.1 Λ(15) MC * K Σ example: 1 energy and angle bin out of Σ π Invariant Mass (GeV) subtract off Σ(1385), Λ(15), K assigned the remaining contribution to the Λ(145) K. Moriya (IU) Λ(145) lineshape July / 4

32 Fit to Lineshape With MC Templates counts Σ p π Wbin: 3 anglebin: <W<.5 CM.7<cosθ K <.8 data Σ(1385) MC Λ(145) MC ver.1 Λ(15) MC * K Σ sum of MC χ /ndf: 4.16 example: 1 energy and angle bin out of Σ π Invariant Mass (GeV) subtract off Σ(1385), Λ(15), K assigned the remaining contribution to the Λ(145) K. Moriya (IU) Λ(145) lineshape July / 4

33 Fit to Lineshape With MC Templates counts Σ p π Λ(145) MC ver. Wbin: 3 anglebin: <W<.5 CM.7<cosθ K <.8 data Σ(1385) MC Λ(145) MC ver.1 Λ(15) MC * K Σ sum of MC χ /ndf:.9 example: 1 energy and angle bin out of Σ π Invariant Mass (GeV) subtract off Σ(1385), Λ(15), K assigned the remaining contribution to the Λ(145) K. Moriya (IU) Λ(145) lineshape July / 4

34 Fit to Lineshape With MC Templates counts Σ p π Wbin: 3 anglebin: <W<.5 CM.7<cosθ K <.8 data residual example: 1 energy and angle bin out of Σ π Invariant Mass (GeV) subtract off Σ(1385), Λ(15), K assigned the remaining contribution to the Λ(145) K. Moriya (IU) Λ(145) lineshape July / 4

35 Outline 1 Introduction What is the Λ(145)? Chiral Unitary Theory of the Λ(145) CLAS Analysis Introduction to JLab and CLAS Decay Channels of Interest Σ (1385) and K Background Fit to Extract Λ(145) Lineshape 3 Results Λ(145) Lineshape Results Λ(145) Cross Section Results Λ(15) Cross Section Results Λ(145)/Λ(15)/Σ(1385) Cross Section Comparison 4 Conclusion K. Moriya (IU) Λ(145) lineshape July / 4

36 Results of Lineshape dσ/dm [µb/gev] <E γ < <W<.5 Σ π thresholds - Σ π weighted average Σ π - Σ π PDG Breit-Wigner Preliminary Σ π Invariant Mass [GeV] lineshapes do appear different for each Σπ decay mode Σ π decay mode has peak at highest mass, narrow than Σ π lineshapes are summed over acceptance region of CLAS difference is less prominent at higher energies K. Moriya (IU) Λ(145) lineshape July / 4

37 Results of Lineshape dσ/dm [µb/gev] <E γ <1.99.5<W<.15 Σ π thresholds Σ π Invariant Mass [GeV] - Σ π weighted average Σ π - Σ π PDG Breit-Wigner Preliminary lineshapes do appear different for each Σπ decay mode Σ π decay mode has peak at highest mass, narrow than Σ π lineshapes are summed over acceptance region of CLAS difference is less prominent at higher energies K. Moriya (IU) Λ(145) lineshape July / 4

38 Results of Lineshape dσ/dm [µb/gev] <E γ <3.7.55<W<.65 Σ π thresholds - Σ π weighted average Σ π - Σ π PDG Breit-Wigner Preliminary Σ π Invariant Mass [GeV] lineshapes do appear different for each Σπ decay mode Σ π decay mode has peak at highest mass, narrow than Σ π lineshapes are summed over acceptance region of CLAS difference is less prominent at higher energies K. Moriya (IU) Λ(145) lineshape July / 4

39 d$/dm I (µb/gev)! " Theory Prediction From Chiral Unitary Approach! # " $ Chiral Unitary Model Prediction! Lineshape of #(145)! "! % p & K "! predicted to depend on "! decay channel!" Invariant Mass (GeV) E ' 1.7 GeV %! J. C. $ # d( "! Nacher, ) 1 E. Oset, H. (1) 1 () ) () (1)* () T $ T $ Re Toki, A. Ramos, Phys. Lett. & T T B ' $ O& T ' dm 3 I 6! " # $ 455, 55 (1999).!! " " d(" (! ) 1 (1) 1 () ) () (1)* () T $ T # Re & T T ' $ O& T '! dm 3 I Chiral Lagrangian 6mB FSI d(" (! Channel ) Coupling 1 ) () () T $ O& T ' dm 3 I! I("!) = {,1,} not in an isospin eigenstate!!" Invariant Mass (GeV) I= contributions negligible! Interference between I= "! d$ ("! ) 1 (1) 1 () % Re () (1)* () T " T " # T T $ " O # T $ and I=1 amplitudes modifies ΣdM 3 I π decay mode6 peaks at highest mass, most distributions narrow! " d$ ("! ) 1 (1) 1 () % Re () (1)* () T " T! # T T $ " O # T difference $ dm in3lineshapes I 6 is due to interference of isospin terms in d$ ("! ) 1 () calculation % (T (I) () T represents " amplitude O # T $ of isospin I term) dm 3 I we have started trying fits to the resonance amplitudes J. C. Nacher et al., Nucl. Phys. B455, 55 Apr--9, NSTAR9, Beijing R. A. Schumacher, Carnegie Mellon University 1 d(/dm I (* K. Moriya (IU) Λ(145) lineshape July / 4

40 Λ(145) Differential Cross Section Results [µb] c.m. dσ dcosθ K Wbin: 3.15<W<.5 (1.994<E <.9) γ weighted Σ Σ - π Σ π total/3 - π c.m. cosθ K lines are fits with 6 rd order Legendre polynomials clear turnover of Σ π channel at forward angles theory: contact term only, no angular dependence for interference experiment: able to see strong isospin AND angular interference effect K. Moriya (IU) Λ(145) lineshape July 11 / 4

41 [µb] c.m. dσ dcosθ K Λ(145) Differential Cross Section Results Wbin: 6.45<W<.55 (.73<E <.996) γ weighted Σ Σ - π Σ π total/3 - π c.m. cosθ K lines are fits with 6 rd order Legendre polynomials clear turnover of Σ π channel at forward angles theory: contact term only, no angular dependence for interference experiment: able to see strong isospin AND angular interference effect K. Moriya (IU) Λ(145) lineshape July 11 / 4

42 [µb] c.m. dσ dcosθ K Λ(145) Differential Cross Section Results Wbin: 8.65<W<.75 (3.73<E <3.561) γ weighted Σ Σ - π Σ π total/3 - π c.m. cosθ K lines are fits with 6 rd order Legendre polynomials clear turnover of Σ π channel at forward angles theory: contact term only, no angular dependence for interference experiment: able to see strong isospin AND angular interference effect K. Moriya (IU) Λ(145) lineshape July 11 / 4

43 Λ(15) Differential Cross Section Comparison ] - [µb/gev d dt σ Σ π average:.474<e - p K average: E - p K average: E - p K average: E - p K average: E - p K average: E Preliminary <.73 γ =.44 γ =.53 γ =.565 γ =.68 γ =.69 γ t-t [GeV ] binning is in t t min good agreement with pk channel from CLAS (unpublished) data provided by R. de Vita et al. (INFN Genova) K. Moriya (IU) Λ(145) lineshape July 11 1 / 4

44 Extrapolation of Cross Sections Ad hoc functions were chosen to fit the measured cross sections total cross section σ tot depends strongly on how cross section is extrapolated final result is a statistical mean of the various fit functions used Σ(1385) 1 c.m. measured dσ/dcosθ K nd order Legendre 3rd order Legendre exp. 1st order Legendre [µb] 1 exp. nd order Legendre exp. 1st order Legendre exp. 3rd order Legendre exp. 3rd order Legendre exp. nd order Legendre double exp. 1st order Legendre dσ c.m. dcosθ K Preliminary c.m. cosθ K K. Moriya (IU) Λ(145) lineshape July 11 / 4

45 Extrapolation of Cross Sections Ad hoc functions were chosen to fit the measured cross sections total cross section σ tot depends strongly on how cross section is extrapolated final result is a statistical mean of the various fit functions used Λ(145) 1 c.m. measured dσ/dcosθ K nd order Legendre 3rd order Legendre exp. 1st order Legendre [µb] 1 exp. nd order Legendre exp. 1st order Legendre exp. 3rd order Legendre exp. 3rd order Legendre exp. nd order Legendre double exp. 1st order Legendre dσ c.m. dcosθ K Preliminary c.m. cosθ K K. Moriya (IU) Λ(145) lineshape July 11 / 4

46 Extrapolation of Cross Sections Ad hoc functions were chosen to fit the measured cross sections total cross section σ tot depends strongly on how cross section is extrapolated final result is a statistical mean of the various fit functions used Λ(15) 1 c.m. measured dσ/dcosθ K nd order Legendre 3rd order Legendre exp. 1st order Legendre exp. nd order Legendre exp. 3rd order Legendre [µb] 1 exp. 1st order Legendre exp. 3rd order Legendre exp. nd order Legendre double exp. 1st order Legendre dσ c.m. dcosθ K Preliminary c.m. cosθ K K. Moriya (IU) Λ(145) lineshape July 11 / 4

47 Extrapolated Total Cross Sections final result is a statistical mean of the various fit functions used Σ(1385) [µb] measured σ tot nd order Legendre exp. 1st order Legendre exp. 3rd order Legendre exp. nd order Legendre double exp. 1st order Legendre weighted average ± standard deviation 3rd order Legendre exp. nd order Legendre exp. 1st order Legendre exp. 3rd order Legendre σ tot Preliminary E γ [GeV] K. Moriya (IU) Λ(145) lineshape July 11 3 / 4

48 Extrapolated Total Cross Sections final result is a statistical mean of the various fit functions used Λ(145) [µb] σ tot Preliminary measured σ tot nd order Legendre exp. 1st order Legendre exp. 3rd order Legendre exp. nd order Legendre double exp. 1st order Legendre weighted average ± standard deviation 3rd order Legendre exp. nd order Legendre exp. 1st order Legendre exp. 3rd order Legendre E γ [GeV] K. Moriya (IU) Λ(145) lineshape July 11 3 / 4

49 Extrapolated Total Cross Sections final result is a statistical mean of the various fit functions used Λ(15) [µb] measured σ tot nd order Legendre exp. 1st order Legendre exp. 3rd order Legendre exp. nd order Legendre double exp. 1st order Legendre weighted average ± standard deviation 3rd order Legendre exp. nd order Legendre exp. 1st order Legendre exp. 3rd order Legendre σ tot.6.4. Preliminary E γ [GeV] K. Moriya (IU) Λ(145) lineshape July 11 3 / 4

50 Extrapolated Total Cross Sections final result is a statistical mean of the various fit functions used comparison of Σ(1385), Λ(145), Λ(15) [µb] weightedaverage σ tot Preliminary Λ(145) weighted average of extrapolated Λ(145) Σ(1385) weighted average of extrapolated Σ(1385) Λ(15) weighted average of extrapolated Λ(15) E γ K. Moriya (IU) Λ(145) lineshape July 11 3 / 4

51 Conclusion Most precise measurement of Λ(145) for any reaction Strong hints of dynamical nature Difference in lineshapes observed Strong effects of both isospin I = and I = 1 Hints of dynamical nature of Λ(145)? Shifts in opposite direction compared to theory Difference in dσ/dcosθ c.m. behavior observed K Again, effects of both isospin I = and I = 1 Cross sections for Σ(1385) and Λ(15) also measured K. Moriya (IU) Λ(145) lineshape July 11 4 / 4

52 Fit to Lineshape With MC Templates counts Σ n π Wbin: 3 anglebin: <W<.5 CM.7<cosθ K <.8 data Σ(1385) MC Λ(145) MC Λ(15) MC * K Σ sum of MC χ /ndf:.6 example: 1 energy and angle bin out of Σ π Invariant Mass (GeV) subtract off Σ(1385), Λ(15), K Σ π phase space assigned the remaining contribution to the Λ(145) K. Moriya (IU) Λ(145) lineshape July 11 1 / 11

53 - M(Σ π ) vs M(K π ) Plots 1.8,π ) M(Σ kinematic boundary Λ(15) Wbin: 3.15 <W<.5 - data kfit Σ only: Λ(145) M(K,π ) low energy bin acceptance is good over entire area K. Moriya (IU) Λ(145) lineshape July 11 / 11

54 - M(Σ π ) vs M(K π ) Plots. kinematic boundary Wbin: 8 1,π ) M(Σ <W<.75 - data kfit Σ only: Λ(15) Λ(145) M(K,π ) high energy bin acceptance is good over entire area K. Moriya (IU) Λ(145) lineshape July 11 / 11

55 Effect of K on Lineshape 1.95 < W [GeV] <.5 (below K threshold) Wbin: <W<.5 5 data kfit Σ only: 8319 * no K : kinematic boundary Λ(15) 1.55 K Λ(15) ) -,π M(Σ 1.45 Λ(145) 1.45 Λ(145) M(K,π ) K vs Y mass plot for Σ channel K. Moriya (IU) Λ(145) lineshape July 11 3 / 11

56 Effect of K on Lineshape 1.95 < W [GeV] <.5 (below K threshold) <E γ < <W<.5 Σ - π weighted average Σ - π Σ π PDG Breit-Wigner dσ/dm [µb/gev] Σ π thresholds Preliminary Σ π Invariant Mass [GeV] extracted lineshape K. Moriya (IU) Λ(145) lineshape July 11 3 / 11

57 Comparison of Lineshapes for Two Σ Channels dσ/dm [µb/gev] <E γ <1.99.5<W< Preliminary - - Σ π p π π - - Σ π n π π weighted average PDG Breit-Wigner Σ π Invariant Mass [GeV] K. Moriya (IU) Λ(145) lineshape July 11 4 / 11

58 Comparison of Lineshapes for Two Σ Channels dσ/dm [µb/gev] 1.47<E γ <.73.35<W< Preliminary - - Σ π p π π - - Σ π n π π weighted average PDG Breit-Wigner Σ π Invariant Mass [GeV] K. Moriya (IU) Λ(145) lineshape July 11 4 / 11

59 Comparison of Lineshapes for Two Σ Channels dσ/dm [µb/gev] <E γ < <W<.75 Preliminary - - Σ π p π π - - Σ π n π π weighted average PDG Breit-Wigner Σ π Invariant Mass [GeV] K. Moriya (IU) Λ(145) lineshape July 11 4 / 11

60 Λ(145) Comparison of Two Σ Channels [µb].3.5. Wbin:.5<W<.15 (1.77<E <1.994) γ - - π - π - Σ π p π - Σ π n π weighted Σ π c.m. dσ dcosθ K c.m. cosθ K K. Moriya (IU) Λ(145) lineshape July 11 5 / 11

61 Λ(145) Comparison of Two Σ Channels [µb] c.m. dσ dcosθ K Wbin: 5.35<W<.45 (.474<E <.73) γ - π - π - Σ π p π - Σ π n π weighted Σ π c.m. cosθ K - K. Moriya (IU) Λ(145) lineshape July 11 5 / 11

62 Λ(145) Comparison of Two Σ Channels [µb] c.m. dσ dcosθ K Wbin: 8.65<W<.75 (3.73<E <3.561) γ - π - π - Σ π p π - Σ π n π weighted Σ π c.m. cosθ K - K. Moriya (IU) Λ(145) lineshape July 11 5 / 11

63 Λ(15) Comparison of Two Σ Channels <E γ <1.99.5<W<.15 Preliminary [µb] dcosθ dσ Σ π p π π - - Σ π n π π - weighted Σ π CM cosθ K K. Moriya (IU) Λ(145) lineshape July 11 6 / 11

64 Λ(15) Comparison of Two Σ Channels <E γ <.73.35<W<.45 Preliminary [µb] dcosθ dσ Σ π p π π - - Σ π n π π - weighted Σ π CM cosθ K K. Moriya (IU) Λ(145) lineshape July 11 6 / 11

65 Λ(15) Comparison of Two Σ Channels.9 [µb] dcosθ dσ <E γ < <W< Σ π p π π - - Σ π n π π - weighted Σ π Preliminary CM cosθ K K. Moriya (IU) Λ(145) lineshape July 11 6 / 11

66 Outline 5 Backup Slides 6 Spin and Parity K. Moriya (IU) Λ(145) lineshape July 11 7 / 11

67 J P of Λ(145) no previous direct experimental evidence for the spin and parity (PDG assumes 1/ ) Note on the Λ(145) 1998 PDG, R.H. Dalitz How do we measure these quantities? spin measure distribution into Σπ flat distribution is best evidence possible for J = 1/ parity measure polarization of Σ from Λ(145) Polarization direction as a function of Σ decay angle will be determined by J P of Λ(145) polarization θ Σ Λ(145) Σ polarization π K. Moriya (IU) Λ(145) lineshape July 11 8 / 11

68 Determination of Spin Fit to Σπ distribution is FLAT cosθ Y χ /ndf from average: φ Y consistent with J = 1/ fits to higher moments may be necessary K. Moriya (IU) Λ(145) lineshape July 11 9 / 11

69 s-wave, p-wave Scenario L = (s-wave) P Σ = P Λ L = 1 (p-wave) P Σ = P Λ ˆn(θ Σ ) Σ Σ P Λ θ Σ P Σ P Λ θ Σ P Σ Λ(145) Λ(145) Λ(145) Σπ is s-wave J P = 1/ Λ(145) Σπ is p-wave J P = 1/ K. Moriya (IU) Λ(145) lineshape July 11 1 / 11

70 Determination of Parity polarization of Λ(145) in direction to production plane is measured W =.6 GeV forward K angles 1.55<W<.65.6<cosθ K <.7 s-wave use reaction: Λ(145) Σ π, Σ pπ very large hyperon decay parameter α =.98 background is 1% Σ(1385) P z p-wave cosθ Σ K. Moriya (IU) Λ(145) lineshape July / 11

71 Determination of Parity polarization of Λ(145) in direction to production plane is measured W =.6 GeV forward K angles 1.55<W<.65.7<cosθ K <.8 s-wave use reaction: Λ(145) Σ π, Σ pπ very large hyperon decay parameter α =.98 background is 1% Σ(1385) P z p-wave cosθ Σ K. Moriya (IU) Λ(145) lineshape July / 11

72 Determination of Parity polarization of Λ(145) in direction to production plane is measured W =.6 GeV forward K angles use reaction: Λ(145) Σ π, Σ pπ very large hyperon decay parameter α =.98 P z background is 1% cosθ Σ(1385) Σ <W<.65.8<cosθ K <.88 s-wave p-wave K. Moriya (IU) Λ(145) lineshape July / 11

73 Determination of Parity polarization of Λ(145) in direction to production plane is measured W =.6 GeV forward K angles use reaction: Λ(145) Σ π, Σ pπ very large hyperon decay parameter α =.98 P z background is 1% cosθ Σ(1385) Σ <W<.65.8<cosθ K <.88 s-wave p-wave polarization does not change with Σ angle (θ Σ ) K. Moriya (IU) Λ(145) lineshape July / 11

74 Determination of Parity polarization of Λ(145) in direction to production plane is measured W =.6 GeV forward K angles use reaction: Λ(145) Σ π, Σ pπ very large hyperon decay parameter α =.98 P z background is 1% cosθ Σ(1385) Σ <W<.65.8<cosθ K <.88 s-wave p-wave polarization does not change with Σ angle (θ Σ ) J P = 1/ is confirmed K. Moriya (IU) Λ(145) lineshape July / 11

75 Determination of Parity polarization of Λ(145) in direction to production plane is measured W =.6 GeV forward K angles use reaction: Λ(145) Σ π, Σ pπ very large hyperon decay parameter α =.98 P z background is 1% cosθ Σ(1385) Σ <W<.65.8<cosθ K <.88 s-wave p-wave polarization does not change with Σ angle (θ Σ ) J P = 1/ is confirmed furthermore, this measured Σ polarization is the Λ(145) polarization K. Moriya (IU) Λ(145) lineshape July / 11

76 Determination of Parity polarization of Λ(145) in direction to production plane is measured W =.6 GeV forward K angles use reaction: Λ(145) Σ π, Σ pπ very large hyperon decay parameter α =.98 P z background is 1% cosθ Σ(1385) Σ <W<.65.8<cosθ K <.88 s-wave p-wave polarization does not change with Σ angle (θ Σ ) J P = 1/ is confirmed furthermore, this measured Σ polarization is the Λ(145) polarization Λ(145) is produced with 4% polarization K. Moriya (IU) Λ(145) lineshape July / 11