強磁場天体におけるニュートリノー反ニュートリノ振動Neutrino-antineutrino oscillations in magnetized astrophysical sites

新学術「地下宇宙」第7回超新星ニュートリノ研究会 1/7-8, 20217th Supernova Neutrino Workshop, 1/7-8, 2021

佐々宏和、滝脇知也Hirokazu Sasaki, Tomoya Takiwaki

国天台NAOJ

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Neutrino oscillations in magnetic field

ne

nµ

nt

nµ

nt

ne ne

nµ

nt

nµ

nt

ne

B=0 B=0

n – n oscillations may be possible in strong magnetic field

1. We demonstrate n-n oscillations in various matter potentials2. We check the possibility of n-n oscillations in core-collapse supernovae

Ando and Sato, PRD68 (2003) 023003→ Information of particle physics(n magnetic moment, Dirac or Majorana..) Yoshida et al., PRD80 (2009) 125032

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Equation of motion of neutrino oscillations

・Liouville- von Neumann equation:

・Hamiltonian:

・Density matrix:rq : 3×3 n density matrix rq : 3×3 n density matrix Xq :Correlations between n and n

r

Sajad and Volpe, Phys.Lett.B790(2019)545-550

n n

Sajad, PRD101 (2020) 103032

・Angle averaged ne number density:

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0.1

0.15

0.2

0.25

0.3

0 200 400 600 800 1000

<ρ

ee>

r[cm]

Ye=0.45

λe=0.1Ωmag

λe=Ωmag

λe=10Ωmag

λe=102Ωmag

Neutrino oscillations are suppressed in a dense matter ( le =102Wmag )

<ree

>

r[cm]

Ye=0.45Results of n-n oscillations in different le

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0.1

0.15

0.2

0.25

0.3

0 200 400 600 800 1000

<ρ

ee>

r[cm]

λe=102Ωmag

Ye=0.45Ye=0.49Ye=0.5

Ye=0.51Ye=0.55

Neutrino oscillations occur around Ye〜0.5 even in dense matter→ Wmag >|le -ln|∝|2Ye-1| is required for active n-n oscillations

Results of n-n oscillations in different Ye

<ree

>

r[cm]

le=102Wmag

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Possibility of n-n oscillations in core-collapse supernovae

・Strength of vacuum potential:

・Strength of matter potential:

・Strength of neutrino self interaction:

,

・Strength of magnetic potential:

Magnetic field on the surface of n sphere

The necessary condition for n-n oscillations

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10-8

10-6

10-4

10-2

100

102

104

100 1000

Po

ten

tial [

cm-1

]

Radius [km]

λζωη

Ωmag

t=31ms

B0 =1014G

B0 =1012G

Comparison of potentials in an early explosion phase 7/9

10-8

10-6

10-4

10-2

100

102

104

100 1000

Pote

ntia

l [cm

-1]

Radius [km]

λζωη

Ωmag

Magnetars (B〜1014 G) may allow n-n oscillations

t=331ms

Comparison of potentials in a later explosion phase

B0 =1014G

B0 =1012G

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Summary

・It is expected that properties of particle physics can be extracted from neutrino-antineutrino oscillations in strong magnetic field in astrophysical sites

・We also investigate the possibility of neutrino-antineutrino oscillations in core-collapse supernovae by using matter profiles obtained in supernova simulations

・Our results imply that neutrino-antineutrino oscillations in magnetic field would bepossible in a supernova explosion scenario which forms a magnetar (B>1014G) whenthe value of neutrino magnetic moment is 10-12µB

・We carry out demonstration of neutrino-antineutrino oscillations in various parametersets of matter potential. We find that neutrino-antineutrino oscillations are suppressedin dense matter. However, such matter suppression disappears around Ye〜0.5

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