Kp atoms

1
Kp atoms
p- (or p)
Electromagnetic force
v
2.9 keV
0.10 c
E (1s) m a2 / 2
rB (1s) 1 / m a 250 fm
p0
Ko
g
(m reduced mass 109 MeV)
K (or K-)

• Strong force
• DE 10 eV stronger binding
• p-K decays to p0K0 t 4 fs
• (pK- decays to p0K0)

73000 revolutions
?
?
Prediction from pK scattering data
a1, a3 scattering lengths S-wave, i 1/2, 3/2
2
Kp scattering data
m(Kp)
a1,a3 poorly known
repulsive
a1 0.17 to 0.34 mp-1 a3 - 0.07 to - 0.14
mp-1
i 3/2
a3
0.6 1.0 1.4 1.8
Better measurements needed
i 1/2
attractive
a1
1) Scalar mesons 0

• Two scalar nonets with the
• strange members
• K0(1430)
• does the very broad k exist ?

k
slope d a k for k 0
a1
3
2) ChPT predictions
successful for pp- atoms (Leutwyler, Gasser,
Colangelo et al.)
extension to s-quarks
a3
does not agree with ChPT (p4)
Dispersion relations
a1 0.224 0.022 a3 -0.045 0.008
mp-1
Büttiker 03
a1
Best data
expect 20 lifetime measurement
Estabrooks78
4
approved until at least 2008
Modification DIRAC II
Principle Kp dissociation in thin target low Q
rel pairs competes with lifetime
of atom

• vs nr. low Qrel pairs has been calculated

N2 electrons C4F10 pions Aerogel kaons, protons
UniZH Aerogel 2006

4 - 8 GeV/c
24 GeV p
-
5
Cosmic ray test setup
Hamamatsu R1584 (UV-window)
Aerogel n 1.05
Trigger
Event rate 0.1 Hz
absorption strong at short l
6
Try this
10 cm aerogel n1.05
Npe
aerogel layers and tetratex (without WLS)
Only aerogel
WLS
POPOP
TPB
pT
Other WLS
p-terphenyl (pT)
Npe for 15 cm aerogel (n1.008) as a function of
K-momentum
Intensity
Wavelength (nm)
240
280
320
360
400