Spin-Isospin excitations as quantitative constraint for the Skyrme tensor force

KITPC, Jun 14th, 2012

Spin-Isospin excitations as quantitative constraint for the Skyrme tensor force

Chunlin BaiDepartment of Physics, Sichuan University

Chengdu, China

● Tensor effects on the excited states

● GT and SD constraint on the tensor force● Tests of the constraint

● Recent studies in open-shell nuclei

● Skyrme parameter sets with tensor force

● Conclusion and outlook

KITPC, Jun 14th, 2012

Skyrme parameter sets with tensor force

The tensor terms postulated by Skyrme: Nucl. Phy. 9, 615(1959)

Skyrme parameter sets which include tensor force:

Fl. Stancu et. al, PLB68, 108(1977), B. A. Brown et. al, PRC74, 061303(2006)

T >0,U>0

G. Colò et. al, PLB644, 227(1977), D. M. Brink et. al, PRC74, 061303(2006)

T >0,U<0

T. Lesinski et. al. PRC76, 014312(2007)

G-Matrixinteraction

Single-particleenergies

Ground stateproperties

T ±,U ±

KITPC, Jun 14th, 2012

Tensor effects on GT states

Bai , Sagawa, Zhang, Zhang, Colò, Xu, Phys. Lett. B675, 28(2009)

• Main peak

• Low energy tail

KITPC, Jun 14th, 2012

Tensor effects on Charge-exchange SD

Exp. FromT. Wakasa et. al., PRC 84, 014614(2011)

Bai, Zhang, Sagawa, Zhang, Colò, Xu,PRL 105,072501(2010)

The SD 1- state is shifted downward dramatically by the tensor RPA correlations.

In T43, T >0, U<0In SLy5+Tw, T>0, U>0

KITPC, Jun 14th, 2012

Tensor effects in M1 excitations

Cao, Colò, Sagawa, Bortignon, Sciacchitano, PRC 80, 064304 (2009)

KITPC, Jun 14th, 2012

GT and SD constraint on the tensor force

Bai, Zhang, Sagawa, Zhang, Colò, Xu, PRC83,054316(2011);

The exp.main peak energy of SD and GT in 90Zr and 208Pb can be the constraints by requiring the condition● In TIJ family, only T21, T32, T43, and T54 fulfill the condition; ● SD 1- states strongly constrain the value of T;● Together with SD, GT main peak can be used to constrain value of U.

exp2.5

thE E MeV

KITPC, Jun 14th, 2012

Tests of the constraints by SD in 16O

Bai, Sagawa, Colo, Zhang, Zhang,PRC 84, 044329(2011)

KITPC, Jun 14th, 2012

Tests of the constraints by IVSM in 90Zr and 208Pb

K. Miki et. al., PRL 2012

KITPC, Jun 14th, 2012

Recent studies in open-shell nucleiHFB+pnQRPA (canonical basis) calculation details:

● In HFB T=1 pairing is adjusted to reproduce the neutron pairing gap of 120Sn

● In QRPA cut-off neutron states with 2 610nv

Choosing of the pairing interaction:

HFB

pnQRPA

The strength of the T=0 pairing is not well evaluated,In N. Vinh Mau, arXiv 0711, 3173 (2007), f=1.36,In our calculation f = 0.0, 0.5, 1, 1.5, 1.7

● In HFB cut-off of the quasi-particle energy: 180 MeV

KITPC, Jun 14th, 2012

GT excitations in Sn isotopes

T=0 pairing has almost no effect on the main peak energies.

0 5 10 15 20 25 300

2

4

6

8

10

12

14

0 5 10 15 20 25 300 5 10 15 20 25 30

0 5 10 15 20 25 300

8

16

0 5 10 15 20 25 300 5 10 15 20 25 30

GT

str

engt

h (M

eV-1)

112Sn

114Sn

f=0.0 f=0.5 f=1.0 f=1.5 f=1.7

116Sn

GT

str

engt

h (M

eV-1)

Ex (MeV)

118Sn

Ex (MeV)

120Sn

Ex (MeV)

124Sn

KITPC, Jun 14th, 2012

112 114 116 118 120 122 1246

8

10

12

14

16

18

EG

T M

eV

A

exp T21 T32 T43 T54 Te1 Te2

GT peak energy in Sb isotopes

E

th-E

exp

< 1.5 MeV

GT excitations in Sb isotopes

KITPC, Jun 14th, 2012

Conclusion and outlook

● Main peak energy of GT and charge-exchange SD transitions in closed shell nuclei can supply good constraint for tensor force;

● In media heavy nuclei such as Sn isotopes, the T=0 pairing force has negligible effects on the main GT peaks;

● GT main peak of media heavy nuclei such as Sn isotopes can also supply good constraint for the tensor force;

● GT excitations in other isotopes and isotonics will be studied;

● Other spin-isospin excitations and the relevant quantities will be studied so as to find constraints for the tensor force.

KITPC, Jun 14th, 2012

collaboratorsG. Colò, INFN , Italy

K. Miki, RCNP, Japan

H. Sagawa, Aizu univ. Japan

F. R. Xu, PKU, China

H. Q. Zhang, CIAE, China

X. Z. Zhang, CIAE, China

KITPC, Jun 14th, 2012