61 research outputs found
Cosmology in General Massive Gravity Theories
We study the cosmology of general massive gravity theories with five
propagating degrees of freedom. This large class of theories includes both the
case with a residual Lorentz invariance as the cases with simpler rotational
invariance. We find that the existence of a nontrivial homogeneous FRW
background, in addition to selecting the lorentz-breaking case, implies in
general that perturbations around strict Minkowski or dS space are strongly
coupled. The result is that dark energy can be naturally accounted for in
massive gravity but its equation of state w_eff has to deviate from -1. We find
indeed a relation between the strong coupling scale of perturbations and the
deviation of w_eff from -1. Taking into account current limits on w_eff and
submillimiter tests of the Newton's law as a limit on the possible strong
coupling regime, we find that it is still possible to have a weakly coupled
theory in a quasi dS background. Future experimental improvements may be used
to predict w_eff in a weakly coupled massive gravity theoryComment: 15 page
Weak Massive Gravity
We find a new class of theories of massive gravity with five propagating
degrees of freedom where only rotations are preserved. Our results are based on
a non-perturbative and background-independent Hamiltonian analysis. In these
theories the weak field approximation is well behaved and the static
gravitational potential is typically screened \`a la Yukawa at large distances,
while at short distances no vDVZ discontinuity is found and there is no need to
rely on nonlinear effects to pass the solar system tests. The effective field
theory analysis shows that the ultraviolet cutoff is (m M_PL)^1/2 ~ 1/\mu m,
the highest possible. Thus, these theories can be studied in weak-field regime
at all the phenomenologically interesting scales, and are candidates for a
calculable large-distance modified gravity.Comment: 5 page
Present and Future K and B Meson Mixing Constraints on TeV Scale Left-Right Symmetry
We revisit the transitions in the and neutral
meson systems in the context of the minimal Left-Right symmetric model. We take
into account, in addition to up-to-date phenomenological data, the
contributions related to the renormalization of the flavor-changing neutral
Higgs tree-level amplitude. These contributions were neglected in recent
discussions, albeit formally needed in order to obtain a gauge independent
result. Their impact on the minimal LR model is crucial and twofold. First, the
effects are relevant in meson oscillations, for both CP conserving and CP
violating observables, so that for the first time these imply constraints on
the LR scenario which compete with those of the sector (plagued by
long-distance uncertainties). Second, they sizably contribute to the indirect
kaon CP violation parameter . We discuss the bounds from and
mesons in both cases of LR symmetry: generalized parity () and
charge conjugation (). In the case of , the interplay
between the CP-violation parameters and leads us
to rule out the regime of very hierarchical bidoublet vacuum expectation values
. In general, by minimizing the scalar field
contribution up to the limit of the perturbative regime and by definite values
of the relevant CP phases in the charged right-handed currents, we find that a
right-handed gauge boson as light as 3 TeV is allowed at the 95% CL. This
is well within the reach of direct detection at the next LHC run. If not
discovered, within a decade the upgraded LHCb and Super B factories may reach
an indirect sensitivity to a Left-Right scale of 8 TeV.Comment: Refs added + comment
A Finite Quantum Symmetry of M(3,C)
The 27-dimensional Hopf algebra A(F), defined by the exact sequence of
quantum groups A(SL(2,C))->A(SL_q(2))->A(F), q^3=1, is studied as a finite
quantum group symmetry of the matrix algebra M(3,C), describing the color
sector of Alain Connes' formulation of the Standard Model. The duality with the
Hopf algebra H,investigated in a recent work by Robert Coquereaux, is
established and used to define a representation of H on M(3,C) and two
commuting representations of H on A(F).Comment: Amslatex, 17 pages, only Reference [DHS] modifie
Finite Energy of Black Holes in Massive Gravity
In GR the static gravitational potential of a self-gravitating body goes as
1/r at large distances and any slower decrease leads to infinity energy. We
show that in a class of four-dimensional massive gravity theories there exists
spherically symmetric solutions with finite total energy, featuring an
asymptotic behavior slower than 1/r and generically of the form .
This suggests that configurations with nonstandard asymptotics may well turn
out to be physical. The effect is due to an extra field coupled only
gravitationally, which allows for modifications of the static potential
generated by matter, while counterbalancing the apparently infinite energy
budget.Comment: 4 page
Left-Right Symmetry at FCC-hh
We study the production of right-handed bosons and heavy neutrinos
at a future 100 TeV high energy hadron collider in the context of Left-Right
symmetry, including the effects of gauge-boson mixing. We estimate
the collider reach for up to 3/ab integrated luminosity using a multi-binned
sensitivity measure. In the Keung-Senjanovi\'c and missing energy channels, the
3 sensitivity extends up to and 37 TeV, respectively. We
further clarify the interplay between the missing energy channel and the
(expected) limits from neutrinoless double beta decay searches, Big Bang
nucleosynthesis and dark matter.Comment: 19 pages, version to appear in PR
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