335 research outputs found
Chaotic Inflation with a Fractional Power-Law Potential in Strongly Coupled Gauge Theories
Models of chaotic inflation with a fractional power-law potential are not
only viable but also testable in the foreseeable future. We show that such
models can be realized in simple strongly coupled supersymmetric gauge
theories. In these models, the energy scale during inflation is dynamically
generated by the dimensional transmutation due to the strong gauge dynamics.
Therefore, such models not only explain the origin of the fractional power in
the inflationary potential but also provide a reason why the energy scale of
inflation is much smaller than the Planck scale.Comment: 5 page
Dynamical Fractional Chaotic Inflation -- Dynamical Generation of a Fractional Power-Law Potential for Chaotic Inflation
Chaotic inflation based on a simple monomial scalar potential, V(phi) ~
phi^p, is an attractive large-field model of inflation capable of generating a
sizable tensor-to-scalar ratio r. Therefore, assuming that future CMB
observations will confirm the large r value reported by BICEP2, it is important
to determine what kind of dynamical mechanism could possibly endow the inflaton
field with such a simple effective potential. In this paper, we answer this
question in the context of field theory, i.e. in the framework of dynamical
chaotic inflation (DCI), where strongly interacting supersymmetric gauge
dynamics around the scale of grand unification dynamically generate a
fractional power-law potential via the quantum effect of dimensional
transmutation. In constructing explicit models, we significantly extend our
previous work, as we now consider a large variety of possible underlying gauge
dynamics and relax our conditions on the field content of the model. This
allows us to realize almost arbitrary rational values for the power p in the
inflaton potential. The present paper may hence be regarded as a first step
towards a more complete theory of dynamical chaotic inflation.Comment: 68 pages, 7 figures, 2 tables, 2 appendice
Cosmological Selection of Multi-TeV Supersymmetry
We discuss a possible answer to the fundamental question of why nature would
actually prefer low-scale supersymmetry, but end up with a supersymmetry scale
that is not completely natural. This question is inevitable if we postulate
that low-energy supersymmetry is indeed realized in nature, despite the null
observation of superparticles below a TeV at the Large Hadron Collider. As we
argue in this paper, superparticles masses in the multi-TeV range can, in fact,
be reconciled with the concept of naturalness by means of a cosmological
selection effect--a selection effect based on the assumption of an exact
discrete R-symmetry that is spontaneously broken by gaugino condensation in a
pure supersymmetric Yang-Mills theory. In such theories, the dynamical scale of
the Yang-Mills gauge interactions is required to be higher than the
inflationary Hubble scale, in order to avoid the formation of domain walls.
This results in a lower limit on the superparticle masses and leads us to
conclude that, according to the idea of naturalness, the most probable range of
superparticle masses is potentially located at the multi-TeV, if the
inflationary Hubble rate is of O(10^{14}) GeV. Our argument can be partially
tested by future measurements of the tensor fraction in the Cosmic Microwave
Background fluctuations.Comment: 16 pages, 3 figure
Lepton Asymmetric Universe
The recent observation of He implies that our universe has a large lepton
asymmetry. We consider the Affleck-Dine (AD) mechanism for lepton number
generation. In the AD mechanism, non-topological solitons called L-balls are
produced, and the generated lepton number is confined in them. The L-balls
protect the generated lepton number from being converted to baryon number
through the sphaleron processes. We study the formation and evolution of the
L-balls and find that the universe with large lepton asymmetry suggested by the
recent He measurement can be realized.Comment: 12 pages, 1 figur
Enhancement of second-order gravitational waves at Q-ball decay
The recent observation of He favors a large lepton asymmetry at the big
bang nucleosynthesis. If Q-balls with a lepton charge decay after the
electroweak phase transition, such a large lepton asymmetry can be generated
without producing too large baryon asymmetry. In this scenario, Q-balls
dominate the universe before the decay and induces the sharp transition from
the early matter-dominated era to the radiation-dominated era. In this
transition, the gravitational waves (GWs) are enhanced through a second-order
effect of the scalar perturbations. We evaluate the density of the produced GWs
and show that pulsar timing array observations can probe this scenario
depending on the amplitude of the scalar perturbations.Comment: 16 pages, 4 figure
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