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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