835 research outputs found
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
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
Back to 1974: The -onium
We show that the 750 GeV di-photon excess could be explained by the
onium system of a new QCD-like theory with fermions vectorial
under the SM. Beside the spin-0 di-photon singlet this scenario predicts almost
degenerate colored scalars and spin-1 resonances analogous to the in
QCD. All these states are within the reach of the LHC. An apparent large width
can be explained as due to production of excited states with splitting .Comment: 6 pages. v2: QCD effects and splitting of SU(2) multiplets added. v3:
final version to appear in PL
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
Accidental Composite Dark Matter
We build models where Dark Matter candidates arise as composite states of a
new confining gauge force, stable thanks to accidental symmetries. Restricting
to renormalizable theories compatible with SU(5) unification, we find 13 models
based on SU(N) gauge theories and 9 based on SO(N). We also describe other
models that require non-renormalizable interactions. The two gauge groups lead
to distinctive phenomenologies: SU(N) theories give complex DM, with
potentially observable electric and magnetic dipole moments that lead to
peculiar spin-independent cross sections; SO(N) theories give real DM, with
challenging spin-dependent cross sections or inelastic scatterings. Models with
Yukawa couplings also give rise to spin-independent direct detection mediated
by the Higgs boson and to electric dipole moments for the electron. In some
models DM has higher spin. Each model predicts a specific set of lighter
composite scalars, possibly observable at colliders.Comment: 39+9 pages, 5 figures. v2: final version to appear on JHE
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