We reanalyze the proton decay in the minimal SU(5) SUGRA GUT model. Unlike previous analyses, we take into account a Higgsino dressing diagram of dimension 5 operator with right-handed matter fields (RRRR operator). It is shown that this diagram gives a dominant contribution for p → K + ν τ over that from LLLL operator, and decay rate of this mode can be comparable with that of p → K + ν µ which is dominated by the LLLL contribution. It is found that we cannot reduce both the decay rate of p → K + ν τ and that of p → K + ν µ simultaneously by adjusting relative phases between Yukawa couplings at colored Higgs interactions. Constraints on the colored Higgs mass M C and a typical squark and slepton mass mf from Super-Kamiokande limit become considerably stronger due to the Higgsino dressing diagram of the RRRR operator: M C > 6.5 × 10 16 GeV for mf < 1 TeV, and mf > 2.5 TeV for M C < 2.5 × 10 16 GeV.

New inflationary solutions to the Einstein equation are explicitly constructed in a simple five-dimensional model with an orbifold extra dimension S 1 /Z 2 . We consider inflation caused by cosmological constants for the five-dimensional bulk and the four-dimensional boundaries. In our solutions the extra dimension is static, and the background metric has a non-trivial configuration in the extra dimension. In addition to the solution for a vanishing bulk cosmological constant, which has already been discussed, we obtain solutions for a non-zero one.

We derive a full set of exact, analytic expressions for the annihilation of the lightest neutralino pairs into all two-body tree-level final states in the framework of minimal supersymmetry. We make no simplifying assumptions about the neutralino nor about sfermion masses and mixings other than the absence of explicit CP-violating terms. The expressions should be particularly useful in computing the neutralino WIMP relic abundance without the usual approximation of partial wave expansion. Keywords: Supersymmetric Effective Theories, Cosmology of Theories beyond the SM, Dark Matter. SM fermion-pair (ff) final states were first computed in Ref [10] and for the W W , ZZ and Higgs boson-pair final states in Ref. [11].Given the complexity of analytic expressions presented here and in other papers and due to often different conventions used, it is not doable to perform a real comparison with the literature. Instead, we have performed a numerical check of our cross section with the results obtained by using DarkSusy [22]. We have found, for the same values of input parameters, an impressive agreement, at the level of a few per cent, for all the annihilation channels, which we find reassuring. (Recently another numerical code has been derived [30] and also numerically agreed with DarkSusy.)While the exact analytic expressions presented here are applicable both near and away from special cases where the method of partial wave expansion fails, sometimes one may find it less CPU-time consuming to use the latter one. Starting from our exact cross sections we have therefore derived a complete set of expressions for the usual first two terms of expansion for all the dominant channels. We will present them here as well.The annihilation into ff is often dominant. However, other final states can also play important role, depending on the case. In a previous paper [19] we performed a detailed numerical comparison of the relic abundance computed using the exact formulae with the one obtained using the expansion formulae, for all the channels, including subdominant ones. Our analysis confirmed that the expansion gives highly inaccurate results near resonances and new thresholds. We also showed that very far from such cases the error is typically rather small, of the order of a few per cent. However, we found that, because of the existence of several resonances (Z and the Higgs bosons), the expansion produces large errors, compared to an exact treatment, over a sizeable range of the neutralino mass m χ , even of a several tens of GeV. In other words, the widely used method of expansion may lead to significant errors in a sizeable fraction of the neutralino mass.The plan of the paper is as follows. In Sect. 2 we review the formalism for computing the relic density that we employ. In Sect. 3 we introduce the relevant ingredients of the MSSM and list all the neutralino pair-annihilation channels. Explicit expressions for the annihilation cross secion are given in Sect. 4. In Sect. 5 we discuss expansion and provide a list of formulae fo...

Coannihilation processes provide an important additional mechanism for reducing the density of stable relics in the Universe. In the case of the stable lightest neutralino of the MSSM, and in particular the Constrained MSSM (CMSSM), the coannihilation with sleptons plays a major role in opening up otherwise cosmologically excluded ranges of supersymmetric parameters. In this paper, we derive a full set of exact, analytic expressions for the coannihilation of the lightest neutralino with the sleptons into all two-body tree-level final states in the framework of minimal supersymmetry. We make no simplifying assumptions about the neutralino nor about sfermion masses and mixings other than the absence of explicit CP-violating terms and inter-family mixings. The expressions should be particularly useful in computing the neutralino WIMP relic abundance without the approximation of partial wave expansion. We illustrate the effect of our analytic results with numerical examples and demonstrate a sizeable difference with approximate expressions available in the literature.

We analyze the implications of several recent cosmological and experimental measurements for the mass spectra of the Constrained MSSM (CMSSM). We compute the relic abundance of the neutralino and compare the new cosmologically expected and excluded mass ranges with those ruled out by the final LEP bounds on the lightest chargino and Higgs masses, with those excluded by current experimental values of BR(B → X s γ), and with those favored by the recent measurement of the anomalous magnetic moment of the muon. We find that for tan β ∼ < 45 there remains relatively little room for the mass spectra to be consistent with the interplay of the several constraints. On the other hand, at larger values of tan β the decreasing mass of the pseudoscalar Higgs gives rise to a wide resonance in the neutralino WIMP pair-annihilation, whose position depends on the ratio of top and bottom quark masses. As a consequence, the cosmologically expected regions consistent with other constraints often grow significantly and generally shift towards superpartner masses in the TeV range.