3,985 research outputs found
Rotating Black Holes/Rings at Future Colliders
The hierarchy between the electroweak and Planck scales can be reduced when
the extra dimensions are compactified with large volume or with warped
geometry, resulting in the fundamental scale of the order of TeV. In such a
scenario, one can experimentally study the physics above the Planck scale. We
discuss black hole/ring production at future colliders.Comment: minor corrections in Appendix; irrelevant files delete
Rotating black holes at future colliders II: Anisotropic scalar field emission
This is the sequel to the first paper of the series, where we have discussed
the Hawking radiation from five-dimensional rotating black holes for spin 0,
1/2 and 1 brane fields in the low frequency regime. We consider the emission of
a brane localized scalar field from rotating black holes in general space-time
dimensions without relying on the low frequency expansions.Comment: 12 pages, 24 figure
Higgs inflation in metric and Palatini formalisms: Required suppression of higher dimensional operators
We investigate the sensitivity of Higgs(-like) inflation to higher
dimensional operators in the nonminimal couplings and in the potential, both in
the metric and Palatini formalisms. We find that, while inflationary
predictions are relatively stable against the higher dimensional operators
around the attractor point in the metric formalism, they are extremely
sensitive in the Palatini one: for the latter, inflationary predictions are
spoiled by in the nonminimal couplings , or by in the
Jordan-frame potential (both in
Planck units). This extreme sensitivity results from the absence of attractor
in the Palatini formalism. Our study underscores the challenge of realizing
inflationary models with the nonminimal coupling in the Palatini formalism.Comment: 29 pages, 10 figures; minor typo correction; references adde
Hillclimbing inflation in metric and Palatini formulations
A new setup of cosmic inflation with a periodic inflaton potential and
conformal factor is discussed in the metric and Palatini formulations of
gravity. As a concrete example, we focus on a natural-inflation-like inflaton
potential, and show that the inflationary predictions fall into the allowed
region of cosmic microwave background observations in both formulations.Comment: 8 pages, 9 figure
Higgs inflation still alive
The observed value of the Higgs mass indicates that the Higgs potential
becomes small and flat at the scale around GeV. Having this fact in
mind, we reconsider the Higgs inflation scenario proposed by Bezrukov and
Shaposhnikov. It turns out that the non-minimal coupling of the
Higgs-squared to the Ricci scalar can be smaller than ten. For example,
corresponds to the tensor-to-scalar ratio , which is consistent
with the recent observation by BICEP2.Comment: 7 pages, 3 figures; Version to appear on Physical Review Letters,
footnotes added and expanded, references added, note added (v2
Higgs inflation from Standard Model criticality
The observed Higgs mass GeV leads to the criticality of the
Standard Model, that is, the Higgs potential becomes flat around the scale
GeV for the top mass GeV. Earlier we have proposed a
Higgs inflation scenario in which this criticality plays a crucial role. In
this paper, we investigate detailed cosmological predictions of this scenario
in light of the latest Planck and BICEP2 results. We find that this scenario
can be consistent with the constraint from the running index too. We also
compute the Higgs one-loop effective potential including the Higgs portal
scalar dark matter, with the two-loop renormalization group equations and find
a constraint on the coupling between Higgs and dark matter depending on the
inflationary parameters.Comment: 29 pages, 12 figures; Accepted by PRD(v2
Di-higgs enhancement by neutral scalar as probe of new colored sector
We study a class of models in which the Higgs pair production is enhanced at
hadron colliders by an extra neutral scalar. The scalar particle is produced by
the gluon fusion via a loop of new colored particles, and decays into di-Higgs
through its mixing with the Standard Model Higgs. Such a colored particle can
be the top/bottom partner, such as in the dilaton model, or a colored scalar
which can be triplet, sextet, octet, etc., called leptoquark, diquark, coloron,
etc., respectively. We examine the experimental constraints from the latest
Large Hadron Collider (LHC) data, and discuss the future prospects of the LHC
and the Future Circular Collider up to 100TeV. We also point out that the
2.4 excess in the final state reported by the
ATLAS experiment can be interpreted as the resonance of the neutral scalar at
300GeV.Comment: 27 pages, 10 figures (v1); references added, 28 pages (v2); minor
modifications, published version (v3
Rotating Black Holes at Future Colliders. III. Determination of Black Hole Evolution
TeV scale gravity scenario predicts that the black hole production dominates
over all other interactions above the scale and that the Large Hadron Collider
will be a black hole factory. Such higher dimensional black holes mainly decay
into the standard model fields via the Hawking radiation whose spectrum can be
computed from the greybody factor. Here we complete the series of our work by
showing the greybody factors and the resultant spectra for the brane localized
spinor and vector field emissions for arbitrary frequencies. Combining these
results with the previous works, we determine the complete radiation spectra
and the subsequent time evolution of the black hole. We find that, for a
typical event, well more than half a black hole mass is emitted when the hole
is still highly rotating, confirming our previous claim that it is important to
take into account the angular momentum of black holes.Comment: typoes in eqs(82)-(84) corrected; version to appear in Phys. Rev. D;
references and a footnote added; same manuscript with high resolution
embedded figures available on
http://www.gakushuin.ac.jp/univ/sci/phys/ida/paper
Multiferroicity in the generic easy-plane triangular lattice antiferromagnet RbFe(MoO4)2
RbFe(MoO4)2 is a quasi-two-dimensional (quasi-2D) triangular lattice
antiferromagnet (TLA) that displays a zero-field magnetically-driven
multiferroic phase with a chiral spin structure. By inelastic neutron
scattering, we determine quantitatively the spin Hamiltonian. We show that the
easy-plane anisotropy is nearly 1/3 of the dominant spin exchange, making
RbFe(MoO4)2 an excellent system for studying the physics of the model 2D
easy-plane TLA. Our measurements demonstrate magnetic-field induced
fluctuations in this material to stabilize the generic finite-field phases of
the 2D XY TLA. We further explain how Dzyaloshinskii-Moriya interactions can
generate ferroelectricity only in the zero field phase. Our conclusion is that
multiferroicity in RbFe(MoO4)2, and its absence at high fields, results from
the generic properties of the 2D XY TLA.Comment: 5 pages, 5 figures, accepted in PRB as a Rapid Communicatio
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