We assume that dark matter is comprised of axion-like particles (ALPs) generated by the realignment mechanism in the post-inflationary scenario. This leads to isocurvature fluctuations with an amplitude of order one for scales comparable to the horizon at the time when the ALP field starts oscillating. The power spectrum of these fluctuations is flat for small wave numbers, extending to scales relevant for cosmological observables. Denoting the relative isocurvature amplitude at k * = 0.05 Mpc −1 by f iso , Planck observations of the cosmic microwave background (CMB) yield f iso < 0.31 at the 2σ-level. This excludes the hypothesis of post-inflationary ALP dark matter with masses m a < 10 −20 -10 −16 eV, where the range is due to details of the ALP mass-temperature dependence. Future CMB stage IV and 21-cm intensity mapping experiments may improve these limits by 1-2 orders of magnitude in m a .

The most likely spin assignments of the recently discovered 126 GeV resonance are spin 0 or 2. In order to distinguish the two, we construct an effective Lagrangian model which comprises interactions of a spin-2 electroweak singlet or triplet state with the SM gauge bosons. Within this model, cross sections and differential distributions are calculated and implemented within the Monte Carlo program Vbfnlo, which simulates vector-boson-fusion processes at hadron colliders at NLO QCD accuracy. We study the phenomenology of spin-2 resonances produced in vectorboson-fusion processes at the LHC. Specifically, we consider light Higgs-like spin-2 resonances decaying into two photons and show how angular distributions allow us to distinguish between a Standard Model Higgs and a spin-2 resonance. We also investigate the characteristics of heavy spin-2 resonances which decay into two weak gauge bosons, leading to a four-lepton final state.

After the discovery of the 126 GeV resonance at the LHC, the determination of its features, including its spin, is a very important ongoing task. In order to distinguish the two most likely spin hypotheses, spin-0 or spin-2, we study the phenomenology of a light Higgs-like spin-2 resonance produced in different gluon-fusion and vector-bosonfusion processes at the LHC. Starting from an effective model for the interaction of a spin-2 particle with the SM gauge bosons, we calculate cross sections and differential distributions within the Monte Carlo program Vbfnlo. We find that with specific model parameters such a spin-2 resonance can mimic SM Higgs rates and transverse-momentum distributions in γ γ, W W , and Z Z decays, whereas several distributions allow to separate spin-2 from spin-0, independently of the spin-2 model parameters.

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