Phenomenological aspects of supersymmetric standard models without grand unification

Abstract

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

No-scale scenario with nonuniversal gaugino masses

“…The flipped SU (5) is another example where the non-universality of the gaugino masses naturally arises [25]. The gauge group is SU(5) × U(1) and thus even if the SU(5) part gives a universal contribution the gaugino mass from U(1) in general gives a different mass, violating the universality of the U(1) Y gaugino mass with the rest two.…”

Lower bound on the neutralino mass from new data on CMB and implications for relic neutralinos

“…Previous papers where schemes of this type are considered include the ones in Refs. [2,3,5,6,7,8,9,10,11,12,13,14,15,16,17,18]. In Ref.…”

Light higgsino in heavy gravitino scenario with successful electroweak symmetry breaking

“…where m t is the top mass, mt is the stop mass scale, and A t is the mass scale included in the trilinear scalar term [26]. We represent the top-stop loop contribution explicitly because it is the largest contribution in the Yukawa one.…”