Asymmetric dark matter and effective number of neutrinos

Abstract

We study the effect of the MeV-scale asymmetric dark matter annihilation on the effective number of neutrinos $N_{\rm eff}$ at the epoch of the big bang nucleosynthesis. If the asymmetric dark matter $\chi$ couples more strongly to the neutrinos $\nu$ than to the photons $\gamma$ and electrons $e^-$, $\Gamma_{\chi\gamma, \chi e} \ll \Gamma_{\chi\nu}$, or $\Gamma_{\chi\gamma, \chi e} \gg \Gamma_{\chi\nu}$, the lower mass limit on the asymmetric dark matter is about $18$ MeV for $N_{\rm eff}\simeq 3.0$.Comment: 13 pages, 14 figures, version accepted for publication in Physical Review

Seesaw model and two zero flavor neutrino texture

“…Because the nearly degenerated mass pattern |m 1 | ∼ |m 2 | ∼ |m 3 | is compatible with observed data for the two zero flavor textures, [15][16][17][18][19] we require rank(m D ) = rank(m D ) = 3 for the Dirac mass matrix: e.g., if we allow rank(m D ) < 3, at least one of the neutrino masses m 1 , m 2 , m 3 should vanish and we cannot guarantee the nearly degenerate mass pattern. The Dirac mass matrix with all zero entries in a row or a column such as and with same row or same column such as…”

“…[26][27][28] In the two zero flavor neutrino mass matrix scheme, there are 15 possible combinations of two vanishing independent elements in the flavor neutrino mass matrix. If we require a nonvanishing Majorana effective mass M ee for the neutrinoless double beta decay, the viable textures are the following [15][16][17][18][19]…”

“…Furthermore, to manipulate this rescaling and to obtain systematic estimation of m D can be well provided by our method to evaluate flavor neutrino masses. 19,21 The complete list of the explicit analytical expressions of the rescaled mass matrix with √ M ee is useful to see how the effect of the neutrinoless double beta decay controls the Dirac neutrino masses. This complete list is shown by analytically for the first time in this paper.…”

Simple A4 models for dark matter stability with texture zeros

“…These textures have been extensively studied [5,[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Here for completeness we present some results and give an estimate of the radiative correction for the neutrinoless double beta decay effective mass parameter.…”

Scotogenic dark matter and single-zero textures of the neutrino mass matrix

“…In paricular, the phenomenology of one-zero and two-zero textures was studied in Refs. [57][58][59][60] and [61][62][63][64][65][66][67][68][69][70][71][72][73][74], respectively. Also, the experimental potential of probing the texture-zero models has been discussed.…”