Документ взят из кэша поисковой машины. Адрес оригинального документа : http://nuclphys.sinp.msu.ru/conf/epp10/Sizin.pdf Дата изменения: Sat Sep 7 16:47:53 2013 Дата индексирования: Fri Feb 28 02:17:44 2014 Кодировка:

PLASMON DECAY TO A NEUTRINO PAIR VIA NEUTRINO ELECTROMAGNETIC MOMENTS IN A STRONGLY MAGNETIZED MEDIUM

A. V. Borisov Faculty of Physics, Moscow State University

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P. E. Sizin Department of Higher Mathematics, Moscow State Mining University


We calculate the neutrino luminosity of a degenerate electron gas in a strong magnetic field via plasmon decay to a neutrino pair due to neutrino electromagnetic moments and obtain the relative upper bounds on the effective neutrino magnetic moment.

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The recent review: C. Broggini, C. Giunti, A. Studenikin, Electromagnetic Properties of Neutrinos, Adv. High Energy Phys. 2012, 459526 (2012) [arXiv:1207.3980 [hep-ph]].

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The considered process: Ї (em)

The leading processes: (weak) Ї Ї e-e+ e ± e± Ї Ї

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Conditions:

T µ - me (degenerate electron gas)

µ2 - m2 e H> (electrons occupy only the ground Landau level) 2e µ µ(T = 0) F = m2 + p2 e F

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Under these conditions the Fermi momentum: 2 2ne pF = eH


The -vertex: [ ]

V (k ) = µB k f2 (k 2) + i 5g2 (k 2)

Solar neutrinos [C. Arpesella et al. (Borexino Collab.), Phys. Rev. Lett. 101, 091302 (2008)]: µ < 5.4 в 10-11µB (CL = 90%)

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Reactor (anti)neutrinos [GEMMA experiment: A. G. Beda, V. B. Brudanin, V. G. Egorov et al., Adv. High Energy Phys., 2012, 350150 (2012)] (see D. Medvedev's talk, this conference, 23 Aug) µe < 2.9 в 10-11µB (CL = 90%) Ї


The polarization vectors: ~ F k (2) = , 2 H k F k (3) = 2 H k

The dispersion law (for mode 2):

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2 2 2 2 k 2 = k0 - kz - k = p The plasma frequency:

( p = k0(k = 0) =

)1/2 2 H pF me H0 F

H0 = m2/e = 4.41 в 1013 G e


General expression for neutrino luminosity:
3q



Qem =

d3 k d 3 q d 23(2 )9k0

(2 )4 (4)(q + q - k )|M |2k0nB (k0) q0q0

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2 4 µ p Ї k 2dk Qem = 3 1 2+k 2 48 p -1 0 eT 2 2 µ2 = µ2 (f2 + g2 ) = µ2 + d2 Ї B


The asymptotic cases p T :
4 pT 3 (3) µ2 2 ^ Qem = 2 24 me

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p T :
11/2 3/2 2 p T µ ^ - Tp Qem = e 2 me 3 · 29/2 3/2

Ї µ µ = ^ µB


The relative upper bound on µ (from Qem < Qweak): ^

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p GF me ^ µ < T F (p); p= T 2 [ ]1/2 2 + 2 g 2 B4(p) Ї ЇA F (p) = p gV ; 3 B2(p) xndx Bn(p) = exp(p 1 + x2) - 1
0 2 gV () 0.929,

gV = Ї2



gA = Ї2


=e,µ,

2 gA() = 3/4.

=e,µ,

F (p) F (0) = 2[2 (5)/ (3)]1/2gA 2.275 Ї F (p) gV p 0.964p, Ї p1


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The upper bounds in astrophysical form

For p T : µ < 3.6 в 10-12 T8 ^ T8 = T /(108 ) µ < 7.2 в 10-12 ^

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For T8 = 2:


For p T :

)-1/4 ( 1/2 -12 1 + 0.44H 2 -2 H13 µ < 2.94 в 10 ^ 13 6

H13 = H/(1013 ), 6 = /(106 /3) (for the neutron star crust: ne 0.5/mp)

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For pF me (H13/6 1):
1/2 ^ µ < 3.61 в 10-12 6

For pF me (H13/6 1): ^ µ < 2.94 в 10-12 H13 H13 = 300 : µ < 5.1 в 10-11 ^
1/2


The obtained relative upper bounds: µ < 3.6 в 10-12 T8 , ^ p T pF me pF me p T , p T ,

1/2 µ < 3.61 в 10-12 6 , ^

-12 H 1/2 , µ < 2.94 в 10 ^ 13

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Solar neutrinos (Borexino): µ < 5.4 в 10-11 ^

Reactor antineutrinos (GEMMA): µ < 2.9 в 10-11 ^


The plasmon decay plays a significant role in the cooling of strongly magnetized neutron stars and is the dominant mechanism of their energy losses in a broad parameter range [M. V. Chistyakov and D. A. Rumyantsev, Zh. Eksp. Teor. Fiz. 134, 627 (2008)]. Relative bounds on the effective magnetic moment of the neutrino determine the range of its values where the weak channel of the plasmon decay is more effective than the electromagnetic one.

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