Composite Accidental Axions

We present several models where the QCD axion arises accidentally. Confining gauge theories can generate axion candidates whose properties are uniquely determined by the quantum numbers of the new fermions under the Standard Model. The Peccei-Quinn symmetry can emerge accidentally if the gauge theory is chiral. We generalise previous constructions in a unified framework. In some cases these models can be understood as the deconstruction of 5-dimensional gauge theories where the Peccei-Quinn symmetry is protected by locality but more general constructions are possible.Comment: 24 pages, 3 figure

Cosmological Production of Dark Nuclei

We study the formation of Dark Matter nuclei in scenarios where DM particles are baryons of a new confining gauge force. The dark nucleosynthesis is analogous to the formation of light elements in the SM and requires as a first step the formation of dark deuterium. We compute this process from first principles, using the formalism of pion-less effective theory for nucleon-nucleon interactions. This controlled effective field theory expansion allows us to systematically compute the cross sections for generic SM representations under the assumption of shallow bound states. In the context of vector-like confinement models we find that, for nucleon masses in the TeV range, baryonic DM made of electro-weak constituents can form a significant fraction of dark deuterium and a much smaller fraction of dark tritium. Formation of dark nuclei can also lead to monochromatic photon lines in indirect detection. Models with singlets do not undergo nucleosynthesis unless a dark photon is added to the theory.Comment: 26 pages, 4 figures. v2) improved discussion on indirect detection, refs adde

Non Pauli-Fierz Massive Gravitons

We study general Lorentz invariant theories of massive gravitons. We show that, contrary to the standard lore, there exist consistent theories where the graviton mass term violates Pauli-Fierz structure. For theories where the graviton is a resonance this does not imply the existence of a scalar ghost if the deviation from Pauli-Fierz becomes sufficiently small at high energies. These types of mass terms are required by any consistent realization of the DGP model in higher dimension.Comment: 4 page

Gluequark Dark Matter

We introduce the gluequark Dark Matter candidate, an accidentally stable bound state made of adjoint fermions and gluons from a new confining gauge force. Such scenario displays an unusual cosmological history where perturbative freeze-out is followed by a non-perturbative re-annihilation period with possible entropy injection. When the gluequark has electroweak quantum numbers, the critical density is obtained for masses as large as PeV. Independently of its mass, the size of the gluequark is determined by the confinement scale of the theory, leading at low energies to annihilation rates and elastic cross sections which are large for particle physics standards and potentially observable in indirect detection experiments.Comment: 39 pages, 7 figures. v2: improved discussion of theoretical uncertainties, matching to the published version. References added and typos fixe

On the Tuning and the Mass of the Composite Higgs

We analyze quantitatively the tuning of composite Higgs models with partial compositeness and its interplay with the predicted Higgs mass. In this respect we identify three classes of models, characterized by different quantum numbers of the fermionic colored resonances associated with the top quark, the so-called top partners. The main result of this classification is that in all models with moderate tuning a light Higgs, of 125 GeV mass, requires the presence of light top partners, around 1 TeV. The minimal tuning is comparable to the one of the most attractive supersymmetric models in particular the ones realizing Natural SUSY. This gives further support to an extensive program of top partners searches at the LHC that can already probe the natural region of composite Higgs models.Comment: 32 pages, 14 figures; v2: version published in JHE