1,066 research outputs found
Third Family Quark-Lepton Unification at the TeV Scale
We construct a model of quark-lepton unification at the TeV scale based on an
gauge symmetry, while still having acceptable neutrino masses and
enough suppression in flavor changing neutral currents. An approximate
flavor symmetry is an artifact of family-dependent gauge charges leading to a
natural realization of the CKM mixing matrix. The model predicts sizeable
violation of PMNS unitarity as well as a gauge vector leptoquark which can be produced at the LHC -- both effects
within the reach of future measurements. In addition, recently reported
experimental anomalies in semi-leptonic -meson decays, both in charged and neutral currents, can be accommodated.Comment: 9 pages, 5 tables. Version accepted for publication in PL
Ricci Reheating
We present a model for viable gravitational reheating involving a scalar
field directly coupled to the Ricci curvature scalar. Crucial to the model is a
period of kination after inflation, which causes the Ricci scalar to change
sign thus inducing a tachyonic effective mass for the
scalar field. The resulting tachyonic growth of the scalar field provides the
energy for reheating, allowing for temperatures high enough for thermal
leptogenesis. Additionally, the required period of kination necessarily leads
to a blue-tilted primordial gravitational wave spectrum with the potential to
be detected by future experiments. We find that for reheating temperatures
GeV, the possibility exists for the Higgs field to play
the role of the scalar field.Comment: 9 pages, 6 figure
Audible Axions
Conventional approaches to probing axions and axion-like particles (ALPs)
typically rely on a coupling to photons. However, if this coupling is extremely
weak, ALPs become invisible and are effectively decoupled from the Standard
Model. Here we show that such invisible axions, which are viable candidates for
dark matter, can produce a stochastic gravitational wave background in the
early universe. This signal is generated in models where the invisible axion
couples to a dark gauge boson that experiences a tachyonic instability when the
axion begins to oscillate. Incidentally, the same mechanism also widens the
viable parameter space for axion dark matter. Quantum fluctuations amplified by
the exponentially growing gauge boson modes source chiral gravitational waves.
For axion decay constants GeV, this signal is detectable by
either pulsar timing arrays or space/ground-based gravitational wave detectors
for a broad range of axion masses, thus providing a new window to probe
invisible axion models.Comment: 8 pages, 4 figures. References added, version submitted to JHE
Deconstructed Hypercharge: A Natural Model of Flavour
The flavour puzzle is one of the greatest mysteries in particle physics. A
`flavour deconstruction' of the electroweak gauge symmetry, by promoting at
least part of it to the product of a third family factor (under which the Higgs
is charged) times a light family factor, allows one to address the flavour
puzzle at a low scale due to accidentally realised flavour symmetries.
The unavoidable consequence is new heavy gauge bosons with direct couplings to
the Higgs, threatening the stability of the electroweak scale. In this work, we
propose a UV complete model of flavour based on deconstructing only
hypercharge. We find that the model satisfies finite naturalness criteria,
benefiting from the smallness of the hypercharge gauge coupling in controlling
radiative Higgs mass corrections and passing phenomenological bounds. Our setup
allows one to begin explaining flavour at the TeV scale, while dynamics solving
the large hierarchy problem can lie at a higher scale up to around 10 TeV -
without worsening the unavoidable little hierarchy problem. The low-energy
phenomenology of the model is dominated by a single gauge boson with
chiral and flavour non-universal couplings, with mass as light as a few TeV
thanks to the symmetry. The natural parameter space of the model will
be probed by the HL-LHC and unavoidably leads to large positive shifts in the
-boson mass, as well as an enhancement in . Finally, we show that a future electroweak precision machine such as
FCC-ee easily has the reach to fully exclude the model.Comment: 28 pages, 3 figures, 1 appendix. Version accepted for publication in
JHE
Spatial extension of stochastic Pi calculus
We introduce a spatial extension of stochastic pi-calculus that provides a formalism to model systems of discrete, connected locations. We define the extended stochastic semantics and also give deterministic semantics in terms of a system of ordinary differential equations. We describe two simple examples, one based on a standard epidemic model and one modelling resistance in plant tissues
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