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Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF

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Page 1: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Thomas S. Bauer - NIKHEF

Page 2: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Thomas S. Bauer - NIKHEF

Page 3: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

with ?s

Some questions and critical remarks to the recently reported exotic states:

+{ u u d d s } at 1.540 GeV and

- - = { u d d s s } at 1.862 GeV.

Page 4: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Present experimental status several experiments reporting positive results; all reported signals are not very strong; revisiting an intensively studied domain;

several critical remarks published; possibly other origins of observed effects;

Page 5: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Present experimental status several experiments reporting positive results; all reported signals are not very strong; revisiting an intensively studied domain;

several critical remarks published; possibly other origins of observed effects;

butbut :

no discussion of other results than mass and width;

(almost) no comparison with existing data;

no assessment of consistency of results;

experiments without result refrain to publish ...

Page 6: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

List of experiments:

SPring-8 (Japan) hep-ex/0301020 08 Jul. 2003

CLAS (TJLab) hep-ex/0307018 10 Dec. 2003

SAPHIR (Bonn) hep-ex/0307083 30 Sep. 2003

Hermes (HERA) hep-ex/0312044 22 Jan. 2004

-data (BEBC and Fermilab) hep-ex/0309042 25 Sep. 2003

Diana (ITEP) hep-ex/0304040 18 Sep. 2003

SVD-2 (Protvino) hep-ex/0401024 22 Jan. 2004

NA49 (CERN) hep-ex/0310014 8 Oct. 2003

ZEUS (HERA) ...

e-scatt.

(K+ + Xe)

(p + A)

(p + p)

e-p scatt.

WA89;

Graal;

H1;CoSy;

Hera-B

...

Page 7: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

and resonances

+ {uudds}

decays to n +

and to p K 0

Page 8: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

resonances

- - {ssddu}

decays to - -

Page 9: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

SPring-8

Page 10: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

SPring-8 (LEPS) ( + 12C)

Some salient features: new experiment, optimized for -physics *) ; uses real photons from Synchr. Radiation Source; E < 2.4 GeV;

LH2 target and 12C target - only 12C used;

PID through ToF and magnetic field; recoiling protons via Si-strip detector; correction for Fermi-motion.

*) “new” = 2001. No printed publication except 2 conference contributions + PQ – paper.

Page 11: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

SPring-8 (LEPS)

first evidence for +-state;

produced in : + n + + K-;

+ K+ + n;used C-target;

19 events in peak.

Page 12: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

SPring-8 (LEPS)

Particle Identification: magnetic field

+ Time of Flight

( + Cherenkov )

possible problem: 43 * 106 triggers

8000 events with K+ K-,

final signal = 19 events

need purity of 10-6 !! (including other cuts)

Page 13: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

SPring-8 (LEPS)

A closer look at Fermi motion:

due to nuclear target;

“correlated with Q-value”;

correction crucial for final result!

n- n- n+

Q (MeV) 37 120 107 (MeV) <10 42 ~20

p (cms) 104 193 244

However measured width of + n K+

much smaller than width of !! (20 MeV vs. 42 MeV)

by the way: shouldn’t the width rather be correlated to momentum in cms ...?

which would make things worse.

Page 14: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

SPring-8 (LEPS)

Identification of state relies heavily on absence of (fast) proton:

the Si-strip detector is used as VETO -- this relies crucially on (very) high efficiency. (no info on this found in the available SPRING-8 documents).

(Questions: strip efficiency, coincidence between layers, etc.)

The Veto condition is checked at ± 45 mm around the presumed impact of the proton. this requires knowledge of the complete kinematics – which is not available!

Page 15: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

SPring-8 (LEPS)

(from Nakano et al.)

Page 16: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

SPring-8 (LEPS)

Question:“removing” 5 events destroys peak.

(from Nakano et al.)

Page 17: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

SPring-8 (LEPS)

Question:“removing” 5 events destroys peak.Thus: how can we gain trust in result ?

Answer: Use data on LH2:

must be able to see + p + K0s;

nono problem with proton-veto ;

nono problem with Fermi-motion.(from Nakano et al.)

Note: SPring-8/LEPS can (in principle) trigger on pions of K0s decay.

Page 18: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

CLAS

Page 19: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

CLAS ( + 2D, + 1H )

Some salient features: Large acceptance experiment, several years of operation; domain: Baryon resonances; E < 2.9 GeV and < 5 GeV , (respectively)

H2 target and 2D target ;

PID through ToF and magnetic field; Correction for Fermi-motion (when needed).

Page 20: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

CLAS

attempt: analyze D-target data, assuming + n + + K- , Fermi correction treated as by SPring-8

collaboration:

Problem: “No statistical significant result obtained!”

and

“CLAS ... unfavorable... for direct + photoproduction detection”(Luminita Todor, Seminar@JLAB, Aug. 15, 2003)

--- how to proceed ???

Page 21: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

• require double scattering process to eject proton;

measurement kinematically complete

Goal: n + + + K- ;Problem: no free neutron target ;

apply trick : use n in D-target;

CLAS

Page 22: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

CLAS Prize for re-scattering:

yield goes down (later called “quenching”) .(implicit claim CLAS: “~50 %” )

reported yields:: 124 1520 : 228+: 42

Attention: difficult to compare: acceptances not known, presumably not equal.

yield /yield ≈ 0.4 – probably even larger!

Need Monte Carlo in order to determine acceptance and cross section.

Page 23: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

CLAS -- new data

apparently not yet available, though shown at workshop in Trento, Febr. 12, 2004 two peaks, at 1.528 and 1.578 GeV yield of 1.578 GeV peak is ~2 times stronger

Page 24: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

SAPHIR

Page 25: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

133 M events (taken ~5 years ago)

trigger = 2 charged tracks

signal: ~ 50 eventscorresponds to production

cross section of ~ 200 nb.

SAPHIR (Elsa-Bonn) ( + 1H )

this is “≈ 20 % of , and 1520 cross sections”

– and decreasing with time .

“rising with energy”

Page 26: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

-- another member of the anti-decuplet...

+ = { u u d d s }

- - = { u d d s s }.

Page 27: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

NA49

Page 28: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

NA49 (p-p, √ s = 17 GeV)

p-p scattering at √ s = 17 GeVsignals for -- :

combining - and - cross check with other charge combinations.

can use 0*1530 as

benchmark.

Page 29: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

NA49

Remarks:

opening angle lab > 4.5 º

Page 30: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

NA49

Remarks:

opening angle lab > 4.5 º

lab is not a physical parameter !!!!!!

Page 31: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

NA49

Remarks:

opening angle lab > 4.5 º

lab is not a physical parameter !!!!!!

01530 visible, but weaker than - -

(1860)

(due to some cuts... total *01530 signal is ~150 evts.)

Page 32: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

NA49 versus NA49

Criticism:(Thanks to H.G. Fischer and S. Wenig, CERN, hep-ex / 0401014 – 12 Jan 2004)

NA49 used 1640 - and 551 + events

NA49 sees a total of ~ 150 *0

1530

S.N. Gangule et al. (NP. B128-408,

(1977) report

~ 800 *01530 from S.N. Gangule et al.

Nucl.Phys. B128, 408, (1977)

Page 33: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

NA49 (p-p, √ s = 17 GeV)

--

Page 34: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

NA49 versus (?) WA89 *)

*) taken from Pochodzalla, Mainz, talk at JLab, Oct 2003

Page 35: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

What is hidden beyond 1.8 GeV in

WA89 ??total: ~150 0*

Note: 63 000 ± 6 000 0*

?

Page 36: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

what has NA49 to say about

NA49 + nK+

?

Page 37: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

NA49 + nK+

a) nK+ inv. mass spectrum;

b) deviation from

polynomial;

Page 38: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

NA49 + nK+

a) nK+ inv. mass spectrum;

b) deviation from

polynomial;

c) 30 % of 1520 added as a

hypothetical + ;

d) statistical significance of

added signal.

note: different E-

scale!

Page 39: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Hermes

Page 40: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Hermes (e-A, Ee = 27 GeV)

quoted signal: 54 ... 59 ± 16

How stable is this signal?

Page 41: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Hermes (e-A, Ee = 27 GeV)

First: one can do much more with 33 datapoints...

Page 42: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Hermes (e-A, Ee = 27 GeV)

121

121

40

40

Page 43: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Hermes (e-A, Ee = 27 GeV)

Page 44: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Hermes (e-A, Ee = 27 GeV)

Page 45: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Hermes (e-A, Ee = 27 GeV)

note: width 1670 small (25 ~ 50 MeV/c2)

width 1690 small (50 ~ 70 MeV/c2)

-channel

Page 46: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Hermes -- another regard on these data

pretty superfluous!!

from Hermes publication:

bckgrnd = 5 Gauss + mixing = 6 paramssignal = Gauss (3param)

total = 9 params

bckgrnd = parabola (3 params)signal = Gauss (3param)

total = 6 params 2/n = 0.64

most likely!!

bckgrnd = parabola (3 params) only

total = 3 params 2/n = 1.097

Page 47: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

other work R. A. Arndt, I.I. Strakovsky and R.L. Workman:

(nucl-th/0311030, 10 Nov. 2003)

reexamine existing K+p and K+d database;“how could such a state have been missed”?

“The lack of structure in database implies:

“ a width of an MeV or less , assuming a state exists near 1540 MeV.”

Page 48: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Hera-B

Page 49: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Hera-B (p-A, √ s = 42 GeV)

finally, a signal which one would like to believe...

K0 - p

Page 50: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Hera-B (p-A, √ s = 42 GeV)

finally a signal which we can enhance...

Page 51: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Hera-B (p-A, √ s = 42 GeV)

finally a signal which we can enhance... and let shrink

Page 52: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Hera-B (p-A, √ s = 42 GeV)

and let come back...

Page 53: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Hera-B (p-A, √ s = 42 GeV)

if only we couldn’t make it come and go...

... a signal which we would like to believe...

? ? ? ? ? ? ? ?

let me explain:

Page 54: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Ks – proton as artefact:

1. take the Armenteros-Podolanski plot for Ks and

2. select overlap region between Ks and

Page 55: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

3. add third particle (proton) with momentum ≈ to one of the pions.

Ks – proton as artefact:

Result:

This is a MCgenerated peak!

Page 56: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Hera-B (p-A, √ s = 42 GeV)

this “” signal appears if :

- -Ks ambiguity not 100 % removed;

- clones not 100 % removed

- protons not 100 % identified

Page 57: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Hera-B (p-A, √ s = 42 GeV) REAL RESULT

p likelihood > 0.95

No evidence of resonances in the mass region around 1.530 GeV.

Page 58: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

NA49 versus Hera-B

*0

--

Page 59: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

NA49 versus Hera-B

*0--

note: Resolution Hera-B ≈ 3.5 MeV

note: different scales!

Page 60: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Yields and (taken from publications)

+ (1520)

SPring-8 19 ± 2.8 4.6 ≈ 1500 ≈ 35

CLAS-d 43 ± ? 5.8 ≈ 126 ≈ 212

CLAS-p 27 ± 8 4.8 -- --

SAPHIR 63 ± 13 4.8 -- 530 ± 90

Neutrino 27 ± 8 6.7 -- --

Diana 27 ± ? 4.4 -- --

Hermes ≈ 70 ± 18

≈ 4 ? ? (≈ 400)

SVD-2 ~ 50 ± ? ≈ 5.6

- -

NA49 no signal !

36 ± 6 ? 5.6

Page 61: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Summary

by now, >8 experiments claim positive signals; all signals are weak:

<< 100 events; between ~ 3 and 6 or 7 (could be discussed)

but . . .

Page 62: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

SPring-8: correction for Fermi motion ? Particle identification ? proton veto

through SSD, and only in region where proton expected.

Problems

Page 63: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

CLAS:

Problems - 2

Quenching through rescattering process likely to be strongly underestimated;

Newest results show two peaks:

1.528 GeV and 1.578 GeV first peak agrees with other experiments

SPring-8 Fermi motion correction does not work;

second is new and is not seen by other expts.

Page 64: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

+

SAPHIR: ≈ 200 nb

Problems - 3

Hermes: ≈ 100 ... 200 nb≈ 1.5 .. 3

0.3

equal?? CLAS: ≈ 10 ... 20 nb *)

*) includes rescattering (presumably)

cross section 30 % of 1520 added as a

hypothetical + ;

Page 65: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Problems – 4 --

NA49 claim not confirmed by high-statistics experiments; NA49 doesn’t see established resonances; NA49 even doesn’t see the + ... *)

*) that is to say: if it exists

Page 66: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Problems – 5

Hermes needs * and ** -resonances

to fit background in p-K0;

Note: p-K- channel 30 times more efficient

than p-K0 channel . . .

but doesn’t see well established *** and **** resonances in p-K- channel;

Page 67: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Problems – 6

p-K0 peak can be created by clones together

with excess at K0 - crossing ...

Page 68: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

a way out ??What about the width???

Page 69: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

a way out ??What about the width???How can a state at this energy be so narrow??

Page 70: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

a way out ??What about the width???How can a state at this energy be so narrow??my (an experimentalist’s) theoretical prediction is:

Page 71: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

a way out ??What about the width???How can a state at this energy be so narrow??my (an experimentalist’s) theoretical prediction is :

≈ 10-22 eV

Page 72: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

a way out ??What about the width???How can a state at this energy be so narrow??my (an experimentalist’s) theoretical prediction is :

≈ 107 s

Page 73: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

a way out ??What about the width???How can a state at this energy be so narrow??my (an experimentalist’s) theoretical prediction is :

≈ 107 s

Page 74: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Thomas S. Bauer - NIKHEF

Page 75: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF

Thomas S. Bauer - NIKHEF

Page 76: Th. S. Bauer - NIKHEF Thomas S. Bauer - NIKHEF. Th. S. Bauer - NIKHEF  Thomas S. Bauer - NIKHEF

Th. S. Bauer - NIKHEF