Relativistic study of medium polarization effects

1
Relativistic study of medium polarization
effects on superfluidity in neutron
matter
nuclear
Masayuki Matsuzaki
(Fukuoka University of Education)
2
Medium polarization effect on superfluidity
Neutron matter
reduce pairing gap significantly
reduction is weak
3
Symmetric matter
preliminary
enhance pairing gap
Finite nuclei
enhance pairing gap
4
Relativistic approach (s-? model)
5
Thermodynamics at T0
Liquid-gas
instability !
6
Quantum mechanics
0
calculate meson propagator (q 0)
7
Nucleon propagator
0
k
pha decomposition --- M.Nakano et
al., PRC56, 3287 (1997)
xxx
xxx
xxx
FD
decompositon --- standard
(
)
,
8
(Longitudinal) dielectric function
pha
FD
instability !
instability !
9
Pairing interaction at 1-loop level
10
(Cross section of dielectric function)
free from instability
infra-red cutoff is necessary
0.65 is chosen
11
(instability)
(corrected using a form factor at tree (OBE)
level)
12
Form factor
at every vertex to modulate high mom. interaction
so as to reproduce the result of Bonn-B potential
present
M.M. and T.Tanigawa, NPA683, 406 (2001)
13
FD
attraction
repulsion
pha
s,longitudinal-?attraction, s-?mix repulsion
14
Neutron matter
instability
15
Summary

• Liquid-gas instability occurs at medium density
• Medium polarization enhances gap at low and
  medium density
• At high density, FD enhances gap whereas pha
  reduces gap
• Characteristic cancellation among s,?, and s-?mix
• Result for neutron matter is similar

16
Acknowledgement

• Prof. P. Ring (Munich) for suggesting the problem
• Prof. H.Kouno (Saga) for useful discussions

17
FD
attraction
pha
18
(Preliminary cal.)
pha
FD
OBE
M.M. and P.Ring, nucl-th/9712060