Strange mesons in nuclei. S=1 mesons:  K ( J p =0  )  K* ( J p =1  ). A. Ramos University of Barcelona (JPS+SPHERE meeting, Vila Lanna , Prague 46 September, 2010). in collaboration with : V.K. Magas , E. Oset , R. Molina, L . Tolós , J. Yamagata Sekihara , S. Hirenzaki.
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Strange mesons in nuclei
S=1 mesons:
 K (Jp=0)
 K* (Jp=1)
A. Ramos
University of Barcelona
(JPS+SPHERE meeting, Vila Lanna, Prague 46 September, 2010)
in collaboration with :
V.K. Magas, E. Oset, R. Molina, L. Tolós,
J. YamagataSekihara, S. Hirenzaki
PseudoscalarK mesons in nuclei
OK
X
M. Agnello et al. Phys. Rev. Lett. 94, 212303 (2005)
T. Suzuki et al., Mod. Phys. Lett. A23, 2520 (2008)
M. Agnello et al. Phys. Lett. B654, 80 (2007)
T. Suzuki al. Phys. Rev .C76, 068202 (2007)
E. Oset, H. Toki, Phys. Rev. C74, 015207 (2006)
V.K. Magas, E. Oset and A. Ramos, Phys. Rev C77, 065210 (2008)
V.K. Magas, E. Oset, A. Ramos and H. Toki, Nucl.Phys. A804, 219 (2008)
V.K. Magas, E. Oset, A. Ramos and H. Toki, Phys. Rev. 74 (2006) 025206
Another “evidence” for a very deeply attractive K nucleus potential:
The (K,p) reaction on 12C at KEK
T. Kishimoto et al., Prog. Theor. Phys. 118 (2007) 181
pK = 1 GeV/c
qp < 4.1o
(the most energetic)
plus “coincidence requirement”:
(at least one charged particle in decay counters surrounding the target)
claimed not to affect the spectrum shape
J. Yamagata, H. Nagahiro and S. Hirenzaki, Phys.Rev. C74, 014604 (2006)
deep
shallow
Analysis of T. Kishimoto et al., Prog. Theor. Phys. 118 (2007) 181
Re UK=−60 MeVIm UK=−60 MeV
Re UK=−190 MeVIm UK=−40 MeV
Re UK=−160 MeVIm UK=−50 MeV
The only mechanism for fast proton emission in the Green’s function method is
the quasielastic process K p K p where the lowenergy kaonin the final statefeels a nuclear optical potential and can occupy stable orbits (no width) , unstable orbits, or be in the continuum (quasifree process)
However, there are other mechanisms that can contribute:
Taken from J. Yamagata and S. Hirenzaki,
Eur. Phys. J. A 31, 255{262 (2007)
We implement these processes in a Monte Carlo simulation of K absorption in nuclei
Monte Carlo simulation
(details in next talk by V. Magas)
Proton spectrum
V.K. Magas, J. YamagataSekihara, S. Hirenzaki, E. Oset and A. Ramos, Phys. Rev. C81, 024609 (2010).
No coincidence

1Nabsorption, rescattering
2N absorption, rescattering
Comparison with KEK data:
Oursimulationshouldconsider the coincidence requirement of KEKPS E548
“The experiment measures the proton PLUS at least one charged particle in the decay counters surrounding the target”
The simulation of such coincidence requirement is tremendously difficult, because it would imply keeping track of all charged particles coming out from all possible scatterings and decays.
The best we can do is to eliminateprocesses that, for sure, cannot have a coincidence: quasielastic K p K p events where neither the p nor the Ksuffer secondary collisions. (In this type of processes the fast p moves forward and the K escapes undetected through the back).
minimal coincidence requirement
Comparison with KEK data:
The coincidence requirement removes a substantial fraction of events and changes the shape of the spectrum drastically
Comparison with KEK data:
Supp. ~ 1.0
Supp. ~0.7
Low energy p – multiparticle final states
should be less supressed!
Vector K* mesons in nuclei
From (K,K*) reaction in nuclei
(see V. Magas’ talk)
The study of vector meson properties in the nuclear medium has received a lot of attention, since they are tied to fundamental aspects of QCD
ρ meson: KEK325, CLASg7, CERES, NA60
ω meson: NA60, CBELSA/TAPS
ϕ meson: KEK325, LEPS, COSYANKE
Less attention has been paid to the K* meson!
(probably because it does not decay into dileptons).
=
+
K* N interaction in free space:
(coupledchannels model)
E. Oset, A. Ramos, Eur.Phys.J. A44 (2010) 431
channels:
K*N
ωΛ, ωΣ
ρΛ, ρΣ
ϕΛ, ϕΣ
K*Ξ
Tij = Vij + Vil GlTlj
transition potential
From local hidden gauge formalism
Bando et al. Phys. Rev. Lett. 54, 1215 (85); Phys. Rep. 164, 217 (88)
transition potential VB>VB
VVVvertex
Bando et al, PRL 112 (1985)
and Phys. Rep. 164 (1988) 217
KSFR relation
BBV vertex
Klingl, Kaiser, Weise,
NPA 624 (1997) 527
(same swave amplitude as in P B P B Swave scattering)
Loop function G incorporates mass distribution (width) of vector meson
L*
S*
1783, Γ=9
PDG:
Λ(1690) 3/2
Λ(1800) 1/2
1830, Γ=42
PDG:
Σ(1750) 1/2
Our resonances are narrower than
known PDG states because coupling
to pseudoscalarbaryon channels is
not included
K* selfenergy in the medium
a) K* K p and medium modifications
free decay : G = ImP/MK*= 50 MeV
medium corrections (absorption)
N
N, D
vertex corrections
The K* width increases substantially (factor 2)
due to pion selfenergy in nuclear matter
MK*
=
+
Tij = Vij + Vil GlTlj
=
+
Tij(r) = Vij + VilGl(r)Tlj(r)
b) K* N interaction in the medium:
q.e. process K*N K*N ,
and also new absorption processes: K*N pKN, K*NN KNN
Free space
meson dressing
Medium
Pauli blocking
and
baryon dressing
=
+
+
DressedK* meson:
L. Tolos, R. Molina, E. Oset, and A. Ramos,
arXiv:1006.3454 [nuclth].
K* selfenergy in the medium
K* width at normal nuclear matter density (r0) is 56 times larger than in free space!!
Can it be checked by some reaction in nuclei?? (V. Magas, next talk )
free
Λ(1784)N1
Σ(1830)N1
MK*
Thank you for your attention