properties of the Λ 1405 measured at clas kei moriya ... at clas kei moriya reinhard schumacher...

— MENU 2010 —

Properties of theΛ(1405)

Measured at CLAS

Kei MoriyaReinhard Schumacher

March 31, 2010

Outline

1 IntroductionWhat is the Λ(1405)?Theory of the Λ(1405)

2 CLAS AnalysisSelecting Decay Channels of InterestRemoving Σ0(1385) and K ∗ BackgroundFit to Extract Λ(1405) Lineshape

3 ResultsΛ(1405) Lineshape ResultsΛ(1405) Cross Section ResultsΛ(1520) Cross Section ResultsΛ(1405),Λ(1520),Σ0(1385) Cross Section Comparison

4 Conclusion

K. Moriya (CMU) Λ(1405) lineshape May 2010 2 / 19

What is the Λ(1405)?

• **** resonance just below NK threshold

• JP = 12

−(experimentally unconfirmed)

• decays exclusively to (Σπ)0

• past experiments: the lineshape (= invariant Σπ mass distribution) isdistorted from a simple Breit-Wigner form

• what is the nature of this distorted lineshape?I “normal” qqq-baryon resonanceI dynamically generated resonance in

unitary coupled channel approach


Chiral Unitary Coupled Channel Approach

dynamically generate Λ(1405)

( )J.C. Nacher et al.rPhysics Letters B 455 1999 55–6158

the Bethe–Salpeter equation, and diagrammatically

this is shown in Fig. 2.

The sum implicit in Fig. 2 is easily evaluated. The

t !g . matrix for the process with the j channel in thej

final state is given by means of the vector D sC Pj 1 j

QXas:j

e i s=q e! .!g .t s D q D G T , 8! ."j j l l l j2 # /2M4 f

l

where the on shell factorization of the strong ampli-w x w xtude found in 9 and in 22 for the related electro-

magnetic process has been used. Diagrams where the

photon couples to the mesons or baryons inside the

loops are largely suppressed at threshold. One can

see that the contribution from the photon attached to

the meson vanishes exactly at threshold. This can be

seen by noting that the loop involves a term of the3 ! . ! .type ePHd q q P f q ,q , with f q ,q a scalarL L L L

function. The integral is proportional to q and van-

ishes due to the Coulomb gauge constraint, ePqs0.

Similarly, for small values of the Kq momentum

one can prove that the corrections to the cross sec-! .2 ! qtion are of order krq k,q,K and photon mo-.menta respectively when compared to the dominant

! .terms of Eq. 8 . Analogously, the contribution from

the photon attached to the baryon is of the order of! 0 X0.k yk rq of the corresponding loops in Fig. 2and hence also negligible in the energy range consid-

ered here.! .The particular structure of Eq. 8 allows one to

obtain an easy formula for the invariant mass distri-

bution of the final j state, particularly suited to the

search of a resonance. We find

ds 1 1 MM 1js3 2dM 4 s MsyM2p! .I Ij

=—

2!g .< <t"" j

=l1r2 s,M 2 ,m2 l1r2 M 2 ,M 2 ,m2 ,! . ! .I K I j j

9! .

where M is the invariant mass of the j state, M , mI j j

! .the masses of the j state and l x, y, z the ordinary

Kallen function.¨In Fig. 3 we show dsrdM for the differentI

channels. While all coupled channels collaborate to

Fig. 2. Diagrammatic representation of the meson-baryon finalq ! .state interaction in the g p™K L 1405 process.

! .the built up of the L 1405 resonance, most of them

open up at higher energies and the resonance shape

is only visible in the pqSy, pySq, p 0S 0 channels.

The KN production occurs at energies slightly above

the resonance and the p 0L, with isospin one, onlyprovides a small background below the resonance.

It is interesting to see the different shapes of the

three pS channels. This can be understood in terms

of the isospin decomposition of the states

1 1 1q y< : < : < : < :p S sy 2,0 y 1,0 y 0,0 ,' ' '6 2 3

10! .1 1 1

y q< : < : < : < :p S sy 2,0 q 1,0 y 0,0 ,' ' '6 2 3

11! .1

20 0< : < : < :p S s 2,0 y 0,0 . 12( ! .3 '3Disregarding the Is2 contribution which is neg-

ligible, the cross sections for the three channels go

as:

22 21 1!1. !0. !0. !1.) q y< < < <T q T q Re T T ; p S ,! .2 3 '6

13! .2

2 21 1!1. !0. !0. !1.) y q< < < <T q T y Re T T ; p S ,! .2 3 '614! .

1 2!0. 0 0< <T ; p S . 15! .3

Apr-20-2009, NSTAR2009, Beijing R. A. Schumacher, Carnegie Mellon University 1

Chiral Unitary Model Prediction

!+"!

!0"0!!""

! Lineshape of “#(1405)” predicted to depend on "! decay channel

! J. C. Nacher, E. Oset, H. Toki, A. Ramos, Phys. Lett. B 455, 55 (1999).! Chiral Lagrangian + mB FSI

+ Channel Coupling! I(" !) = {0,1,2} – not in an

isospin eigenstate! I=2 contributions negligible! Interference between I=0

and I=1 amplitudes modifies mass distributions

# $ # $

# $ # $

# $

2 2(1) (0) (0) (1)* (2)

2 2(1) (0) (0) (1)* (2)

0 02(0) (2)

( ) 1 1 2Re

2 3 6

( ) 1 1 2Re

2 3 6

( ) 1

3

I

I

I

dT T T T O T

dM

dT T T T O T

dM

dT O T

dM

$ "

$ "

$ "

" !

! "

!% " " "

!% " ! "

!% "

!" Invariant Mass (GeV)

d$/d

MI (µ

b/G

ev) 1.7

p K

E GeV%

% "" !&

'

J. C. Nacher et al., Phys. Lett. B455, 55 (1999)


Difference in Lineshape

!"#$%& '(#)%$*+,-./&+0$/.#1)#-(

!+"#

!0"0!#"$

! 2#(/3"%4/+-5+6%789:;<=4$/.#1)/.+)-+./4/(.+-(+"!./1%*+1"%((/&+

! >?+!?+@%1"/$A+B?+C3/)A+D?+E-F#A+G?+H%I-3A+0"*3?+2/))?+J+!""A+;;+78KKK<?! !"#$%& 2%L$%(L#%(+M+IJ NOP+

M+!"%((/&+!-Q4&#(L

! P7" !<+R+S:A8ATU+V (-)+#(+%(+#3-34#( /#L/(3)%)/

! PRT+1-()$#WQ)#-(3+(/L&#L#W&/

! P()/$5/$/(1/+W/)X//(+PR:+%(.+PR8+%I4&#)Q./3+I-.#5#/3+I%33+.#3)$#WQ)#-(3

& ' & '

& ' & '

& '

2 2(1) (0) (0) (1)* (2)

2 2(1) (0) (0) (1)* (2)

0 02

(0) (2)

( ) 1 1 2Re

2 3 6

( ) 1 1 2Re

2 3 6

( ) 1

3

I

I

I

dT T T T O T

dM

dT T T T O T

dM

dT O T

dM

( "

( "

( "

$ #

# $

!) $ $ $

!) $ # $

!) $

!" Invariant Mass (GeV)d(/d

MI(*

b/G

ev) 1.7

p K

E GeV+

+ "$, !

-

J. C. Nacher et al., Nucl. Phys. B455, 55

• difference in lineshapes is due to interference of isospin terms incalculation (T(I) represents amplitude of isospin I term)

• distortion of the lineshape is connected to underlying QCD amplitudesthat generate the Λ(1405)

• this analysis will measure all three Σπ channels


Data From CLAS@JLab

• CLAS@Jefferson Lab

• liquid LH2 target

• γ + p→ K+ + Λ(1405)

• real unpolarized photonbeam

• Eγ < 3.84 GeV

• ∼ 20B total triggers

• measure charged particle

I ~p with driftchambers

I timing with TOFwalls


Reaction of Interest

p!!(!0

, ")

52%

48%

100%

64%

!+!!

!0!

0

! + p p(!0)!!

(n)!+!!

K+

+ !(1405)

!!

!+

detected particles K+,p,π− K+,π+,π−

missing particle(s) (π0) (π0,γ) (n)

intermediate hyperon Λ Σ+ Σ0(→ γΛ) Σ+ Σ−

kinematic fit yes no yesreaction Σ(1385) Σ(1385), Λ(1405), Λ(1520)


Reaction of Interest

p!!(!0

, ")

52%

48%

100%

64%

!+!!

!0!

0

! + p p(!0)!!

(n)!+!!

K+

+ !(1405)

!!

!+

33% each?(will be for pure

isospin 0)

detected particles K+,p,π− K+,π+,π−

missing particle(s) (π0) (π0,γ) (n)

intermediate hyperon Λ Σ+ Σ0(→ γΛ) Σ+ Σ−

kinematic fit yes no yesreaction Σ(1385) Σ(1385), Λ(1405), Λ(1520)


Background

• Σ0(1385)→ ΣπI BR(Λπ0) = 88%� BR(Σ±π∓) = 6% each⇒ measure in Λπ0, scale down to each Σπ channel

I influence should be small due to branching ratio• K ∗Σ

I broad width – will overlap with signalI subtract off incoherently

)-π,+M(K0.6 0.7 0.8 0.9 1 1.1

)- π,+ ΣM

(

1.3

1.4

1.5

1.6

1.7

1.8

-110

1

10

Wbin: 3

2.150 <W< 2.250

only: 70414+Σdata kfit


Background




)-π,+M(K0.6 0.7 0.8 0.9 1 1.1

)- π,+ ΣM

(

1.3

1.4

1.5

1.6

1.7

1.8

-110

1

10

Wbin: 3

2.150 <W< 2.250


(1405)Λ

(1520)Λ

*0K


Background




)-π,+M(K0.6 0.7 0.8 0.9 1 1.1

)- π,+ ΣM

(

1.3

1.4

1.5

1.6

1.7

1.8

-110

1

10

Wbin: 3

2.150 <W< 2.250


(1405)Λ

(1520)Λ

*0Kkinematic boundary


Σ(1385) is Fit in Λπ0 Channel (γ + p→ K+ + p + π− + π0)

)0π ΛM(1.2 1.25 1.3 1.35 1.4 1.45 1.5 1.55 1.6 1.65

coun

ts

0

20

40

60

80

100

120

140

160

180

200 Wbin: 2 anglebin: 17

2.050 <W< 2.150

<0.800CMK+θ0.700<cos

data

threshold0π Λ

example:1 energy and anglebin out of ∼ 150

• Σ(1385) is fit with templates of MC ofI Σ(1385) (non-relativistic Breit-Wigner)I K∗+Λ MC

• very good fit resultsK. Moriya (CMU) Λ(1405) lineshape May 2010 9 / 19


)0π ΛM(1.2 1.25 1.3 1.35 1.4 1.45 1.5 1.55 1.6 1.65

coun

ts

0

20

40

60

80

100

120

140

160

180


2.050 <W< 2.150

<0.800CMK+θ0.700<cos

data

threshold0π Λ

(1385) MCΣexample:1 energy and anglebin out of ∼ 150




)0π ΛM(1.2 1.25 1.3 1.35 1.4 1.45 1.5 1.55 1.6 1.65

coun

ts

0

20

40

60

80

100

120

140

160

180


2.050 <W< 2.150

<0.800CMK+θ0.700<cos

data

threshold0π Λ

(1385) MCΣ MCΛ *+K example:

1 energy and anglebin out of ∼ 150




)0π ΛM(1.2 1.25 1.3 1.35 1.4 1.45 1.5 1.55 1.6 1.65

coun

ts

0

20

40

60

80

100

120

140

160

180


2.050 <W< 2.150

<0.800CMK+θ0.700<cos

data

threshold0π Λ

(1385) MCΣ MCΛ *+K

sum of MC/ndf: 1.602χ




Σ(1385) Cross Section From Λπ0 Channel

c.m.K+θcos

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

b]µ [c.

m.

K+

θdc

osσd

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

5th order Legendre fit2.050<W<2.150

<1.994γ1.770<E

Preliminary

• scale by branching ratio and acceptance into each Σπ channel

• BR(Λπ) = 89% � BR(Σπ) = 11%

• Σ0π0 channel does not have Σ(1385)


Fit to Lineshape With MC Templates

Invariant Mass (GeV)π Σ1.3 1.4 1.5 1.6 1.7 1.8

coun

ts

0

100

200

300

400

500

600Wbin: 3 anglebin: 17

2.150 <W< 2.250<0.800CM

K+θ0.700<cosdata

0π p → +Σ


• subtract off Σ(1385), Λ(1520), K∗0

• assigned the remaining contribution to the Λ(1405)




coun

ts

0

100

200

300

400

500


2.150 <W< 2.250<0.800CM

K+θ0.700<cosdata

0π p → +Σ(1385) MCΣ


• subtract off Σ(1385), Λ(1520), K∗0





coun

ts

0

100

200

300

400

500


2.150 <W< 2.250<0.800CM

K+θ0.700<cosdata

0π p → +Σ(1385) MCΣ

(1405) MC ver.1Λ


• subtract off Σ(1385), Λ(1520), K∗0





coun

ts

0

100

200

300

400

500


2.150 <W< 2.250<0.800CM

K+θ0.700<cosdata

0π p → +Σ(1385) MCΣ

(1405) MC ver.1Λ(1520) MCΛ


• subtract off Σ(1385), Λ(1520), K∗0





coun

ts

0

100

200

300

400

500


2.150 <W< 2.250<0.800CM

K+θ0.700<cosdata

0π p → +Σ(1385) MCΣ

(1405) MC ver.1Λ(1520) MCΛ

+Σ *0K example:1 energy and anglebin out of ∼ 150

• subtract off Σ(1385), Λ(1520), K∗0





coun

ts

0

100

200

300

400

500


2.150 <W< 2.250<0.800CM

K+θ0.700<cosdata

0π p → +Σ(1385) MCΣ

(1405) MC ver.1Λ(1520) MCΛ

+Σ *0Ksum of MC

/ndf: 4.162χ


• subtract off Σ(1385), Λ(1520), K∗0





coun

ts

0

100

200

300

400

500


2.150 <W< 2.250<0.800CM

K+θ0.700<cosdata

0π p → +Σ(1385) MCΣ

(1405) MC ver.1Λ(1520) MCΛ

+Σ *0Ksum of MC

/ndf: 2.092χ(1405) MC ver.2Λ


• subtract off Σ(1385), Λ(1520), K∗0





coun

ts

0

100

200

300

400

500


2.150 <W< 2.250<0.800CM

K+θ0.700<cosdata

0π p → +Σresidual


• subtract off Σ(1385), Λ(1520), K∗0



Results of Lineshape

Invariant Mass [GeV]π Σ1.3 1.4 1.5

b/G

eV]

µ/d

M [

σd

0

0.5

1

1.5

2

2.5 <1.99γ1.77<E2.05<W<2.15

thresholdsπ Σ

weighted average-π +Σ0π 0Σ+π -Σ

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




b/G

eV]

µ/d

M [

σd

0

0.2

0.4

0.6

0.8

1<2.73γ2.47<E

2.35<W<2.45

thresholdsπ Σ


PDG Breit-Wigner

Preliminary








b/G

eV]

µ/d

M [

σd

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4<3.56γ3.27<E

2.65<W<2.75

thresholdsπ Σ


PDG Breit-Wigner

Preliminary






Theory Prediction From Chiral Unitary Approach

Apr-20-2009, NSTAR2009, Beijing R. A. Schumacher, Carnegie Mellon University 1

Chiral Unitary Model Prediction

!+"!

!0"0!!""

! Lineshape of “#(1405)” predicted to depend on "! decay channel

! J. C. Nacher, E. Oset, H. Toki, A. Ramos, Phys. Lett. B 455, 55 (1999).! Chiral Lagrangian + mB FSI

+ Channel Coupling! I(" !) = {0,1,2} – not in an

isospin eigenstate! I=2 contributions negligible! Interference between I=0

and I=1 amplitudes modifies mass distributions

# $ # $

# $ # $

# $

2 2(1) (0) (0) (1)* (2)

2 2(1) (0) (0) (1)* (2)

0 02(0) (2)

( ) 1 1 2Re

2 3 6

( ) 1 1 2Re

2 3 6

( ) 1

3

I

I

I

dT T T T O T

dM

dT T T T O T

dM

dT O T

dM

$ "

$ "

$ "

" !

! "

!% " " "

!% " ! "

!% "


d$/d

MI (µ

b/G

ev) 1.7

p K

E GeV%

% "" !&

'

!"#$%& '(#)%$*+,-./&+0$/.#1)#-(

!+"#

!0"0!#"$

! 2#(/3"%4/+-5+6%789:;<=4$/.#1)/.+)-+./4/(.+-(+"!./1%*+1"%((/&+

! >?+!?+@%1"/$A+B?+C3/)A+D?+E-F#A+G?+H%I-3A+0"*3?+2/))?+J+!""A+;;+78KKK<?! !"#$%& 2%L$%(L#%(+M+IJ NOP+

M+!"%((/&+!-Q4&#(L

! P7" !<+R+S:A8ATU+V (-)+#(+%(+#3-34#( /#L/(3)%)/

! PRT+1-()$#WQ)#-(3+(/L&#L#W&/

! P()/$5/$/(1/+W/)X//(+PR:+%(.+PR8+%I4&#)Q./3+I-.#5#/3+I%33+.#3)$#WQ)#-(3

& ' & '

& ' & '

& '

2 2(1) (0) (0) (1)* (2)

2 2(1) (0) (0) (1)* (2)

0 02

(0) (2)

( ) 1 1 2Re

2 3 6

( ) 1 1 2Re

2 3 6

( ) 1

3

I

I

I

dT T T T O T

dM

dT T T T O T

dM

dT O T

dM

( "

( "

( "

$ #

# $

!) $ $ $

!) $ # $

!) $


d(/d

MI(*

b/G

ev) 1.7

p K

E GeV+

+ "$, !

-

J. C. Nacher et al., Nucl. Phys. B455, 55

• Σ−π+ decay mode peaks at highest mass, most narrow

• difference in lineshapes is due to interference of isospin terms incalculation (T(I) represents amplitude of isospin I term)

• we have started trying fits to the resonance amplitudes


Isospin Decomposition• Separate {!"#$, !%#%, !$#"} into I=0 and I=1

amplitude contributions(0) (0)

0ˆ{ } | |

IT T p# &

'( !

(1) (1)

1ˆ{ } | |

IT T p# &

'( !

2 2 2(0) (1) (0) (1)

01

1 1 2cos

3 2 6A T T T T

#)" $!

' " $ *

0 0

2 2(0)1

3A T

#!'

2 2 2(0) (1) (0) (1)

01

1 1 2cos

3 2 6A T T T T

#)$ "!

' " " *

+ ,2

2(0) (1) (2)

3 3 3 3 3 32

( )( , | 0,0) ( , |1,0) ( , | 2,0)

16 ( )

f

i

p mcdI I T I I T I I T

dm W p W# # #

- .

#! ! !

' " "!

0

(0,1,2) (0,1,2) 0

2 2

0

( )( ) ( )

m

T m gm m im q

/

/0

'$ $ 0

2 /q m/ '

0

0

( )( )

q mm

q0 ' 0

(2) (2)

2ˆ{ } | |

IT T p# &

'( !

!1#1phase space factor

Mass-dependent width

for relativistic Breit Wigner


Isospin Decomposition

I=1 contributions

I=0 contribution

!" #

$

!# "

$

0 0

!$

Preliminary


Λ(1405) Differential Cross Section Results

c.m.K+θcos

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

b]µ [ θ

dcosσd

0

0.05

0.1

0.15

0.2

0.25

<2.23γ1.99<E

2.15<W<2.25

Preliminary

Σ+π−Σ0π0

Σ−π+

total/3

• lines are fits with 6rd 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


Λ(1405) Differential Cross Section Results

c.m.K+θcos

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

b]µ [ θ

dcosσd

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

<3.56γ3.27<E

2.65<W<2.75

Preliminary

Σ+π−Σ0π0

Σ−π+

total/3

• lines are fits with 6rd 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


Λ(1520) Differential Cross Section Comparison

]2 [GeV0t-t0 0.5 1 1.5 2 2.5

]-2

b/G

eVµ

[dtσd

0

0.2

0.4

0.6

0.8

1

1.2

<2.730γ

average: 2.474<Eπ Σ=2.440

γ average: E-p K

=2.503γ

average: E-p K=2.565

γ average: E-p K

=2.628γ

average: E-p K=2.690

γ average: E-p K

Preliminary

• binning is in t − tmin

• good agreement with pK− channel from CLAS (unpublished)— data provided by de Vita et al. (INFN Genova)K. Moriya (CMU) Λ(1405) lineshape May 2010 17 / 19

Comparison of Σ(1385)/Λ(1405)/Λ(1520) Cross Sections

c.m.K+θcos

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

b]µ [ θ

dcosσd

0

0.2

0.4

0.6

0.8

1

1.2

<2.23γ1.99<E2.15<W<2.25

modesπ Σ(1405) sum of Λ

π Λ(1385) total from Σ

π Σ(1520) average of 3 Λ

Preliminary

• lines are fits with 5th order Legendre polynomials


Comparison of Σ(1385)/Λ(1405)/Λ(1520) Cross Sections

c.m.K+θcos

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

b]µ [ θ

dcosσd

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

<3.56γ3.27<E2.65<W<2.75

modesπ Σ(1405) sum of Λ

π Λ(1385) total from Σ

π Σ(1520) average of 3 Λ

Preliminary

• lines are fits with 5th order Legendre polynomials


Conclusion

• difference in lineshapes observed

• difference in dσ/dcosθc.m.K+ behavior observed

• doing our own isospin decomposition of resonance amplitudes

• systematics under study

strong dynamical effects being observed for the Λ(1405)

hoping to finalize analysis soon


effect of kinematic fit on resolution

example in 1 bin:• neutron combined with π± reconstructs Σ±

• project on each axis, select ±2σ, exclude other hyperon• diagonal band (K 0 from π+π−) is also excluded

(without kinematic fit)

,n)-!(2M1.2 1.4 1.6 1.8 2

,n)

+ !(2M

1.2

1.4

1.6

1.8

2 Wbin: 2 tbin: 182.050 <W< 2.150

-0.270<t<-0.135missing n: 26355

lines"2±nominal lines"2±kfit

+#

-#


effect of kinematic fit on resolution

example in 1 bin:• neutron combined with π± reconstructs Σ±

• project on each axis, select ±2σ, exclude other hyperon• diagonal band (K 0 from π+π−) is also excluded

(with kinematic fit)

,n)-!(2M1.2 1.4 1.6 1.8 2

,n)

+ !(2M

1.2

1.4

1.6

1.8

2 Wbin: 2 tbin: 182.050 <W< 2.150

-0.270<t<-0.135CL(n)>1: 24408

lines"2±nominal lines"2±kfit

+#

-#




coun

ts

0

50

100

150

200

250

300

350

400 Wbin: 3 anglebin: 172.150 <W< 2.250

<0.800CMK+θ0.700<cos

data

-π n → -Σ(1385) MCΣ(1405) MCΛ(1520) MCΛ

+Σ *0Ksum of MC

/ndf: 2.622χ


• subtract off Σ(1385), Λ(1520), K+Σ−π+ phase space• assigned the remaining contribution to the Λ(1405)


Comparison of Lineshapes for Two Σ+Channels


b/G

eV]

µ/d

M [

σd

0

0.5

1

1.5

2

2.5<1.99γ1.77<E

2.05<W<2.15

-π 0π p → -π +Σ-π +π n → -π +Σ

weighted averagePDG Breit-Wigner

Preliminary




b/G

eV]

µ/d

M [

σd

0

0.2

0.4

0.6

0.8

1 <2.73γ2.47<E

2.35<W<2.45

-π 0π p → -π +Σ-π +π n → -π +Σ


Preliminary




b/G

eV]

µ/d

M [

σd

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

<3.56γ3.27<E

2.65<W<2.75

-π 0π p → -π +Σ-π +π n → -π +Σ


Preliminary


Λ(1405) Comparison of Two Σ+Channels

CMK+θcos

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

b]µ [ θ

dcosσd

0

0.05

0.1

0.15

0.2

0.25

0.3

from fit to 6th Legendre2χ1.3221.4331.164

Wbin: 2

<1.99γ1.77<E

2.05<W<2.150π -π p → -π +Σ-π +π n → -π +Σ

-π +Σweighted

Preliminary



CMK+θcos

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

b]µ [ θ

dcosσd

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

0.22

0.24


Wbin: 5

<2.73γ2.47<E

2.35<W<2.450π -π p → -π +Σ-π +π n → -π +Σ

-π +Σweighted

Preliminary



CMK+θcos

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

b]µ [ θ

dcosσd

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18


Wbin: 8

<3.56γ3.27<E

2.65<W<2.750π -π p → -π +Σ-π +π n → -π +Σ

-π +Σweighted

Preliminary



CMK+θcos

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

b]µ [ θ

dcosσd

0

0.2

0.4

0.6

0.8

1 <1.99γ1.77<E

2.05<W<2.15

0π -π p → -π +Σ-π +π n → -π +Σ

-π +Σweighted

Preliminary



CMK+θcos

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

b]µ [ θ

dcosσd

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

<2.73γ2.47<E

2.35<W<2.45

0π -π p → -π +Σ-π +π n → -π +Σ

-π +Σweighted

Preliminary



CMK+θcos

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

b]µ [ θ

dcosσd

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

<3.56γ3.27<E

2.65<W<2.75

0π -π p → -π +Σ-π +π n → -π +Σ

-π +Σweighted

Preliminary


properties of the Λ 1405 measured at clas kei moriya ... at clas kei moriya reinhard schumacher...

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