Production and Dalitz decays of baryon resonances in p+p … · Production and Dalitz decays of...

Production and Dalitz decays of baryon resonances

in p+p interactions at Ekin=1.25 and 3.5 GeV

beam energy with HADES

Witold Przygoda, Jagiellonian University

for the HADES Collaboration

18 June 2013

MESON NET Meeting 2013 17-19 June 2013, Prague, Czech Republic

The HADES Spectrometer

Side View

START

FW

1 m

RPC (from 2010)

ϕ: full, θ: 18 - 85 e+e- pair acceptance 0.35 ~80.000 channels, segmented solid or LH2 target

SIS18 beam: π, p, A

Δm/m ~ 2-3% at /

Versatile detector for rare particle decays :

• dielectrons (e+, e-)

• strangeness: , K,0 , -

• upgrade(2010): new DAQ (20 KHz), Tof-RPC (tof ~80 ps) 2

G. Agakichiev et al. Eur. Phys. J. A41 (2009) 243

p+p @ 1.25 GeV - plan

𝒑 + 𝒑 elementary reactions at E = 1.25 GeV below production threshold

are well situated to investigate

Δ(1232) Dalitz decay

I. HADRON ANALYSIS (npπ+, ppπ0)

II. LEPTON ANALYSIS (ppe+e-, ppe+e-)

Witold Przygoda (MESONNET 2013) 3

𝑝 + 𝑝

𝑝∆+ 𝑝∆++

𝑝𝒏𝝅+ 𝑝𝒑𝝅𝟎 𝑛𝒑𝝅+

𝑝𝒑𝒆+𝒆−

𝑝𝑝𝒆+𝒆−𝜸

Resonance model Production: OPEM

Λ𝜋 fitted in accordance with the data (𝛬𝜋 = 0.75) V. Dmitriev et al. Nucl. Phys. A459

(1986) 503

Form factor at vertices:

𝐹 𝑞2 =Λ𝜋

2 − 𝑚𝜋2

Λ𝜋2 − 𝑞2

Z. Teis et al., Z. Phys. A356 (1997) 421

4 Witold Przygoda (MESONNET 2013)

G. A

gaki

shie

v et

al.

Eur.

Ph

ys. J

. A 4

8 (

20

12

) 7

4

production (n p π+)


black line – total red line – Δ++(1232) green line – Δ+(1232) blue line – N(1440) yellow – phasespace

in acceptance

OPEM (𝛬𝜋 = 0.75 modified) Δ resonance + FSI + N(1440) small

production (n p π+) - 4π corrected


grey band:

correction with various OPEM parametrisations (𝛬𝜋 = 0.63, 0.75, 1.00)

cross section:

17.5 ± 0.5 mb

”symmetrized”

ACC corrected

2-dim correction matrix:

production (p p π0)

7

Identifying 2 protons • strongly reduces acceptance • amplifies large 4-mom transfer

parametrisation deduced from the npπ+ channel

in acceptance

black line – total red line – Δ+(1232) blue line – N(1440) yellow – phasespace

red line – Δ+(1232)+N(1440) blue line – N(1440)

production (p p π0) - 4π corrected


ACCEPTANCE corrected

”fiducial volume” in angular distribution i.e. -0.6 < cos θ < +0.6

cross section:

see dilepton analysis (next slides)

Acceptance correction:

QED

cloud/core ~ 0.44/0.56

Mee [GeV/c2]

QED

cloud/core ~ 0.99/0.01

M=1.23 M=1.5

M=1.8

Δ Ne+e-

22

2

2

2222

232, qqqΔf Gm

qGGqm C

Δ

EM2

-

dq

)eNe(Δd

M.I. Krivoruchenko et al. Phys. Rev. D65 (2002) 017502

Q. Wann, F. Iachello Int. J. Mod. Phys. A20 (2005) 1846

G. Ramalho, M. T. Peña Phys. Rev. D85 (2012) 113014

Time Like (q2 >0)

(J=3/2) ->N (J=1/2) * transition:

9

q q q

quark core

e+

e-

e-

pion cloud

+ identification via pp 0 { e+e- }

black – pp analysis blue – ppee analysis

ACC corrected

both channels with 2 protons (pp and ppe+e-) support the description of angular distribution according to OPE (modified) with parameter Λ𝜋 = 0.75 Cross section deduced (blue points) 4.25 0.5 mb


E.L.Bratkovskaya et al. Phys. Lett. B348, 283 (1995)

𝜋0 helicity

ACC corrected

+ Dalitz decay via pn+ { pe+e- }

M.I. Krivoruchenko et al. Phys. Rev. D65, 017502 (2002)

form-factors – Very important at higher energy!

Dalitz decay BR

GM(0)~3 GE(0)~0 GC(0)~0

missing mass selection

Mee > 0.15 SIGNAL: 200, CB: 15

11

red line – total black – π0 Dalitz blue line – Δ Dalitz grey band – (VMD)

(pee) angular observables, BR

BR = 𝑁

∆ → 𝑝𝑒+𝑒−

𝑁∆ → 𝑝𝜋0

derived in the ”fiducial area” −0.7 < cos 𝜃𝑝𝑒𝑒

𝐶𝑀 < 0.7

BR = 4.42 10-5 20% (syst.) 9% (stat.)

helicity in agreement with QED

1 + 𝐴 ∙ cos2𝜃 (when neglecting Gc(q) at small q

2)

preliminary


preliminary

p+p @ 3. 5 GeV - plan

𝒑 + 𝒑 elementary reactions at E = 3.5 GeV to investigate the wealth of baryionic resonances

and their properties

I. HADRON ANALYSIS (npπ+, ppπ0)

II. LEPTON ANALYSIS (ppe+e-)


Inclusive e+e- spectrum p+p @ 3.5 GeV

How to treat R N e+e- • mesons produced via baryonic

resonances (R ρ N e+ e- N) • Resonance model with eTFF from model

seems to describe nicely data – only Δ?

J. Weil et al. (GiBUU) Eur. Phys. J. A48 (2012) 111

arxiv.org/abs/1305.3118

14

G. Agakishiev et al. Eur. Phys. J. A 48 (2012) 64

Baryon resonances in p+p @ 3. 5 GeV

15

Resonance model:

production amplitude given by incoherent sum of

resonance contributions, isospin relations

Starting point: S. Teis R parametrization (S. Teis et al., Z. Phys. A356, 421 (1997).),

take 4* resonances + empirical angular distributions

(strong forward-backward peaking)

)()(

MR t

AM

dt

d

Study of 3 connected exclusive channels: • pppp0 and pppn+ to fix R (,N*) cross sections

• Convert Rpe+e- and check in pp ppe+e-

BR(Rpe+e-) : „QED” point-like R-* vertex

M. Zetenyi and Gy. Wolf., Heavy Ion Phys. 17 (2003) 27.

For the overlaping resonances only one

resonance with largest BR(N) selected

Resonance production (HADES acceptance)

Witold Przygoda (MESONNET 2013) 16 P.Salabura

)()(

MR t

AM

dt

d

n p π+

extension of angular parametrisation as a function of t for all resonances

One pion production: acceptance corrected

17

n p π+

p p π0

• ++ (1232) dominant excelent description of -line

shape („Monitz” FF)

• +(1232), N*(1440),N*(1520),..

Exclusive / production in p+p @ 3. 5 GeV


=

=

pp = ½ · pp

N* (1535) fixed from Dalitz plot

N* (1535) ->p BR(42%)

N*(1535) = 1520.15 [mb]

K. Teilab (PhD Thesis) Univ. Frankfurt (2011)

F. Balestra et al. (DISTO) Phys. Rev. Lett. 89 (2002) 092001

Exclusive p+p @ 3.5 GeV (dileptons) 1

no off shell coupling to VM lower limit for e+e- emission experimental for / used missing yield related to low mass resonances

„QED”

point-like RN* vertex

M. Zetenyi, G. Wolf Phys. Rev. C67 (2003) 044002

preliminary

19


no free / production missing yield related to high mass resonances !

M. I. Krivoruchenko, B.V. Martemyanov

Ann. Phys. 296 (2002) 299

extended VDM

preliminary

20


saturation - what about higher resonances?

Δ modification

preliminary

„QED” point-like RN* vertex

+ eTTF Δ(1232) Wan / Iachello

21

CREDITS

𝑻𝒉𝒆 𝑯𝑨𝑫𝑬𝑺 𝑪𝒐𝒍𝒍𝒂𝒃𝒐𝒓𝒂𝒕𝒊𝒐𝒏

Piotr Salabura (spokesperson)

me Manuel Lorenz


Gosia Gumberidze

Adrian Dybczak

BACKUP SLIDES


Normalization – pp elastic

EDDA experiment 46-135⁰ in CM cross section

3.99 0.23 mb

normalization error 7.5%


Partial Wave Analysis proton+proton (isospin I = 1) S – spin, L – orbital momentum, J – total angular momentum

INITIAL PP STATES (-1)S+L+I = -1

for S=0: L even… L=0 (J=0) or L=2 (J=2)… for S=1: L odd… L=1(J=0,1,2) or L=3 (J=2,3,4)…

FINAL STATES S-, P-, D-waves in pp or pn-state P33(1232) and P11(1440) in πN state

J I = 1

0 1S0, 3P0

1 3P1

2 1D2, (3P2,

3F2)

3 3F3


K.N. Ermakov et al. Eur. Phys. J. A47 (2011) 159

Motivation:

Formalism: Andrey Sarantsev talk

(which was on Tuesday)

Input for PWA – other data

Experimental data samples

1628 MeV/c 1760 ± 60 µb 2912

π+ p n

Bonn-Gatchina group http://pwa.hiskp.uni-bonn.de/data.htm

Proton Momentum

Total cross section

Data (events)

950 MeV/c 1217 MeV/c 1279 MeV/c 1341 MeV/c 1389 MeV/c 1437 MeV/c 1485 MeV/c 1536 MeV/c 1581 MeV/c 1628 MeV/c 1683 MeV/c

100 ± 30 µb 2070 ± 90 µb 2850 ± 130 µb 3310 ±190 µb 3700 ± 140 µb 3730 ± 150 µb 3960 ± 150 µb 4200 ± 150 µb 4190 ± 170 µb 4480 ± 200 µb 4500 ± 170 µb

154972 542 615 882 993 914 996 1315 903 688 1086

Proton Momentum

Total cross section

Data (events)

π0 p p


PWA solutions


• several solutions tested • with HADES data only • with all experimental data sets • with resonances Δ and N* only • with / without resonance N* • with / without 3F3 input pw

• systematic tests on missing mass cut • systematic tests on background (Q-factor)

two examples

good data description in various projections but cross sections not

worse data description in some projections but cross sections quite good

PWA (n p π+) – in acceptance


black line – total red line – P33(1232) blue line – P11(1440)


PWA (p p π0) – in acceptance


PWA (n p π+) – 4π black line – total red line – P33(1232) blue line – P11(1440)


PWA (n p π+) – 4π


PWA (p p π0) – 4π



black line – total red line – P33(1232) blue line – P11(1440)


PWA (p p π0) – in acceptance

PWA solutions


n p π+ (17.5 ± 1 mb ) p p π0 (4.3 ± 0.5 mb)

cross section [mb] 14.7 16.9 5.1 4.5

P33(1232) in 4π 61% 60% 74% 93%

P33(1232) in acceptance 50% 66% 88% 105%

P11(1440) in 4π 17% 16% 55% 57%

P11(1440) in acceptance 21% 22% 54% 63%

input partial waves n p π+ p p π0

1S0 3% 12% 8% 10%

1D2 8% 8% 8% 5%

3P0 7% 13% 6% 8%

3P1 27% 29% 15% 18%

3P2 38% 38% 70% 68%

3F2 18% 21% 17% 18%

PWA solutions


input partial wave output (n p π+) output (p p π0)

1S0 2-8% 1S0 P11(1440)-p 1S 3-10% 1S0 P11(1440)-p 1S

1D2 3-6% 1D2 P33(1232)-p 5D 4-8% 1D2 P33(1232)-p 5D

3P0 4-5% 3P0 (pp)(3P1)pi 3P 17-30% 3P0 (pp)(3P1)pi 3P

4-8% 3P0 P11(1440)-p 3P 14-32% 3P0 P11(1440)-p 3P

3P1 8-16% 3P1 P33(1232)-p 3P 10-18% 3P1 P33(1232)-p 3P

0-3% 3P1 (pp)(3P2)pi 5P 0-7% 3P1 (pp)(3P2)pi 5P

3P2 29-36% 3P2 P33(1232)-p 3P 61-75% 3P2 P33(1232)-p 3P

5-14% 3P2 P11(1440)-p 3P 15-33% 3P2 P11(1440)-p 3P

3F2 13-15% (pn)(1P1)pi 3P 20-28% P33(1232)-p 5P

1-2% (pp)(3P1)pi 3P 10% (pp)(3P1)pi 3P

Comparison (4π) PWA and data

Legend: (red line) OPE modified (𝛬𝜋 = 0.75)

(blue line) PWA – resonance P33(1232)

(dashed black) PWA total

(dashed blue) – resonance P11(1440)

n p π+

PWA Δ++ in 4π 61% of total

PWA up-scaled

the same 𝑑𝜎

𝑑𝑀 of Δ++ in the pole


Comparison (4π) PWA and data

Legend: (red line) OPE modified (𝛬𝜋 = 0.75)

(blue line) PWA – resonance P33(1232)

(dashed black) PWA total

(dashed blue) – resonance P11(1440)

p p π0

PWA Δ+ in 4π 74% of total

PWA the same scale


Production and Dalitz decays of baryon resonances in p+p … · Production and Dalitz decays of...

Documents

Transcript of Production and Dalitz decays of baryon resonances in p+p … · Production and Dalitz decays of...