Interpretations of indirect searches for dark matter (DM) require theoretical predictions for the annihilation or decay rates of DM into stable particles of the standard model. These predictions include usually only final states accessible as lowest order tree-level processes, with electromagnetic bremsstrahlung and the loop-suppressed two gamma-ray line as exceptions. We show that this restriction may lead to severely biased results for DM tailored to produce only leptons in final states and with mass in the TeV range. For such models, unavoidable electroweak bremsstrahlung of Z and W -bosons has a significant influence both on the branching ratio and the spectral shape of the final state particles. We work out the consequences for two situations: Firstly, the idealized case where DM annihilates at tree level with 100% branching ratio into neutrinos. For a given cross section, this leads eventually to "minimal yields" of photons, electrons, positrons and antiprotons. Secondly, the case where the only allowed two-body final states are electrons. The latter case is typical of models aimed at fitting cosmic ray e − and e + data. We find that the multimessenger signatures of such models can be significantly modified with respect to results presented in the literature.PACS numbers: 95.35.+d, 95.85.Pw, 98.70.Sa

The formation and evolution of superdense clumps (or subhalos) is studied. Such clumps of dark matter (DM) can be produced by many mechanisms, most notably by spiky features in the spectrum of inflationary perturbations and by cosmological phase transitions. Being produced very early during the radiation dominated epoch, superdense clumps evolve as isolated objects. They do not belong to hierarchical structures for a long time after production, and therefore they are not destroyed by tidal interactions during the formation of larger structures. For DM particles with masses close to the electroweak (EW) mass scale, superdense clumps evolve towards a power-law density profile $\rho(r) \propto r^{-1.8}$ with a central core. Superdense clumps cannot be composed of standard neutralinos, since their annihilations would overproduce the diffuse gamma radiation. If the clumps are constituted of superheavy DM particles and develop a sufficiently large central density, the evolution of their central part can lead to a 'gravithermal catastrophe.' In such a case, the initial density profile turns into an isothermal profile with $\rho \propto r^{-2}$ and a new, much smaller core in the center. Superdense clumps can be bserved by gamma radiation from DM annihilations and by gravitational wave detectors, while the production of primordial black holes and cascade nucleosynthesis constrain this scenario.Comment: 9 pages, 6 eps figures; v2: 7 yr WMAP data included, to appear in PR

We propose the lightest supersymmetric particle (LSP) as a well-suited candidate for superheavy dark matter (SHDM). Various production mechanisms at the end of inflation can produce SHDM with the correct abundance, ΩLSPh 2 ∼ 0.1, if its mass is sufficiently high. In particular, gravitational production requires that the mass mLSP of the LSP is above 3 × 10 11 GeV. Weak interactions remain perturbative despite the large mass hierarchy, mLSP ≫ mZ, because of the special decoupling properties of supersymmetry. As a result the model is predictive and we discuss the relevant cosmological processes for the case of a superheavy neutralino within this scheme.

We investigate possible symmetry properties of the scalar sector of MultiHiggs-Doublet Models, and, to some extent, the generalization of such models to gauge groups other than SU(2) L × U(1) Y . In models with C (charge conjugation) invariance, and where certain quartic terms are not present, the scalar potential is invariant under a group larger than the gauge group, O(4) when the Higgs fields are doublets. If the Higgs fields develop aligned vacuum expectation values, this symmetry will break to an O(3) subgroup, which in general is further broken by loop corrections involving the gauge bosons. Assuming such corrections are small, the physical properties of the Higgs sector will approximately organize into representations of SO(3). If the vacuum expectation values of the Higgs fields are aligned in the direction of the C even fields, the mass spectra of the charged and C odd sectors will be degenerate. Moreover, if the Higgs fields develop a pair of non-aligned vacuum expectation values, so that the charge conjugation symmetry is spontaneously broken (but not the U(1) electromagnetic gauge invariance), a pair of light charged pseudo-Goldstone bosons will appear.

We prove that a generic multi-Higgs-doublet model (NHDM) generally must contain terms in the potential that violate the custodial symmetry. This is done by showing that the O(4) violating terms of the NHDM potential cannot be excluded by imposing a symmetry on the NHDM Lagrangian. Hence we expect higher-order corrections to necessarily introduce such terms. We also note, in the case of custodially symmetric Higgs-quark couplings, that vacuum alignment will lead to up-down mass degeneration; this is not true if the vacua are not aligned.