We calculate the relic abundance of Higgsino-dominant lightest superparticles, taking account of coannihilations with the superparticles which are almost degenerate with the lightest one. We show that their relic abundance is reduced drastically by the coannihilation processes and hence they are cosmologically of no interest.
When the GUT relation on gaugino masses is relaxed, the mass and composition of the lightest neutralino are different from those in the GUT case. We discuss its phenomenological implications on the relic abundance of the neutralinos and on superparticle searches. In particular, we focus on the case where the neutral component of Winos dominates the lightest neutralino. It turns out the Wino-LSP is not a candidate for the dark matter. where g i (i =1, 2, 3) are the gauge coupling constants of the gauge groups (2) L and SU(3) C , respectively, and M i (i =1, 2, 3) the corresponding gaugino mass parameters. Note that this relation holds, independent of the particle content between the electroweak scale and the GUT scale. Therefore, eq. (1) provides an important test of the idea of the GUTs.There are, however, many well-motivated models in which the relationand a flipped SU(5) model [4] whose gauge structure is SU(5) × U(1) X . In the former, M 1 , M 2 and M 3 are unknown parameters which will be determined by string dynamics, whereas in the latter, M 1 is independent of the others. Indeed in the flipped SU(5) it has been argued [5] that, using a RG analysis, |M 1 | ≫ |M 2 | is favored to achieve the correct gauge symmetryIn this paper, we will consider phenomenological aspects of SUSY standard models without the GUT relation (1) which is assumed in most of the literature (see however refs. [6,7,8]). In particular, we are concerned with the mass ratio r ≡ M 1 /M 2 , since it is an important parameter in the neutralino mass matrix as we will explain later. We assume, as usual, that the lightest neutralino is also the lightest superparticle (LSP). To clarify its properties is thus important in SUSY phenomenology from the viewpoints of both accelerator physics and cosmology, especially when the LSP is stable due to a Z 2 symmetry called R-parity. In this paper we will mainly discuss the case 1 of |r| > 1, in which the neutral component of Winos can be a dominant composition of the LSP (see below). Note that this Wino-dominant LSP is never realized under the GUT assumption. On the other hand, some of the details on the case of |r| ≪ 1, where the LSP is mostly the Bino, have been discussed in [7].Throughout this paper, we consider the case of the minimal particle content in the SUSY standard model. With the R-parity conservation, the
The atmospheric neutrino fluxes at the Kamioka site are calculated semianalytically. We investigate the dependence of various physical parameters on the resultant fluxes. Both the absolute value of the fluxes and the (v, +V, )/(v,+V,) ratio agree with those of the previous calculation. In particular, it is found that the (v, + V , )/(v,+V,) ratio is almost independent of the method or the details of calculation.
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