1,361 research outputs found
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
Notes on High Energy Limit of Bosonic Closed String Scattering Amplitudes
We study bosonic closed string scattering amplitudes in the high-energy
limit. We find that the methods of decoupling of high-energy zero-norm states
and the high-energy Virasoro constraints, which were adopted in the previous
works to calculate the ratios among high-energy open string scattering
amplitudes of different string states, persist for the case of closed string.
However, we clarify the previous saddle-point calculation for high-energy open
string scattering amplitudes and claim that only (t,u) channel of the
amplitudes is suitable for saddle-point calculation. We then discuss three
evidences to show that saddle-point calculation for high-energy closed string
scattering amplitudes is not reliable. By using the relation of tree-level
closed and open string scattering amplitudes of Kawai, Lewellen and Tye (KLT),
we calculate the high-energy closed string scattering amplitudes for arbitrary
mass levels. For the case of high-energy closed string four-tachyon amplitude,
our result differs from the previous one of Gross and Mende, which is NOT
consistent with KLT formula, by an oscillating factor.Comment: 14 pages, no figure. Equations and Conclusion adde
Regge Closed String Scattering and its Implication on Fixed angle Closed String Scattering
We calculate the complete closed string high energy scattering amplitudes
(HSA) in the Regge regime for arbitrary mass levels. As an application, we
deduce the complete ratios among closed string HSA in the fixed angle regime by
using Stirling number identities. These results are in contrast with the
incomplete set of closed string HSA in the fixed angle regime calculated
previously. The complete forms of the fixed angle amplitudes, and hence the
ratios, were not calculable previously without the input of zero-norm state
calculation. This is mainly due to the lack of saddle point in the fixed angle
closed string calculation.Comment: 10 pages. v2: typos correcte
New solutions in 3D gravity
We study gravitational theory in 1+2 spacetime dimensions which is determined
by the Lagrangian constructed as a sum of the Einstein-Hilbert term plus the
two (translational and rotational) gravitational Chern-Simons terms. When the
corresponding coupling constants vanish, we are left with the purely Einstein
theory of gravity. We obtain new exact solutions for the gravitational field
equations with the nontrivial material sources. Special attention is paid to
plane-fronted gravitational waves (in case of the Maxwell field source) and to
the circularly symmetric as well as the anisotropic cosmological solutions
which arise for the ideal fluid matter source.Comment: Revtex, 21 pages, no figure
Stokes Phenomena and Quantum Integrability in Non-critical String/M Theory
We study Stokes phenomena of the k \times k isomonodromy systems with an
arbitrary Poincar\'e index r, especially which correspond to the
fractional-superstring (or parafermionic-string) multi-critical points (\hat
p,\hat q)=(1,r-1) in the k-cut two-matrix models. Investigation of this system
is important for the purpose of figuring out the non-critical version of M
theory which was proposed to be the strong-coupling dual of fractional
superstring theory as a two-matrix model with an infinite number of cuts.
Surprisingly the multi-cut boundary-condition recursion equations have a
universal form among the various multi-cut critical points, and this enables us
to show explicit solutions of Stokes multipliers in quite wide classes of
(k,r). Although these critical points almost break the intrinsic Z_k symmetry
of the multi-cut two-matrix models, this feature makes manifest a connection
between the multi-cut boundary-condition recursion equations and the structures
of quantum integrable systems. In particular, it is uncovered that the Stokes
multipliers satisfy multiple Hirota equations (i.e. multiple T-systems).
Therefore our result provides a large extension of the ODE/IM correspondence to
the general isomonodromy ODE systems endowed with the multi-cut boundary
conditions. We also comment about a possibility that N=2 QFT of Cecotti-Vafa
would be "topological series" in non-critical M theory equipped with a single
quantum integrability.Comment: 43 pages, 3 figures; v2:references and comments added (footnote 24
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