144 research outputs found
Chiral cosmic strings in supergravity
We consider F and D-term cosmic strings formed in supersymmetric theories.
Supersymmetry is broken inside the string core, but restored outside. In global
SUSY, this implies the existence of goldstino zero modes, and the string
potentially carries fermionic currents. We show that these zero modes do not
survive the coupling to gravity, due to the super Higgs mechanism. Therefore
the superconductivity and chirality properties are different in global and
local supersymmetry. For example, a string formed at the end of D-term
inflation is chiral in supergravity but non-chiral in global SUSY.Comment: 14 pages, no figure
Unitarity and predictiveness in new Higgs inflation
In new Higgs inflation the Higgs kinetic terms are non-minimally coupled to
the Einstein tensor, allowing the Higgs field to play the role of the inflaton.
The new interaction is non-renormalizable, and the model only describes physics
below some cutoff scale. Even if the unknown UV physics does not affect the
tree level inflaton potential significantly, it may still enter at loop level
and modify the running of the Standard Model (SM) parameters. This is analogous
to what happens in the original model for Higgs inflation. A key difference,
though, is that in new Higgs inflation the inflationary predictions are
sensitive to this running. Thus the boundary conditions at the EW scale as well
as the unknown UV completion may leave a signature on the inflationary
parameters. However, this dependence can be evaded if the kinetic terms of the
SM fermions and gauge fields are non-minimally coupled to gravity as well. Our
approach to determine the model's UV dependence and the connection between low
and high scale physics can be used in any particle physics model of inflation.Comment: 21+6 pages, 1 figure; final version accepted by the journal,
improvements of section
"Signature" neutrinos from photon sources at high redshift
The temperature of the cosmic microwave background increases with redshift;
at sufficiently high redshift it becomes possible for ultrahigh-energy photons
and electrons to produce muons and pions through interactions with background
photons. At the same time, energy losses due to interactions with radio
background and intergalactic magnetic fields are negligible. The energetic
muons and pions decay, yielding a flux of ``signature'' neutrinos with energies
eV. Detection of these neutrinos can help understand the
origin of ultrahigh-energy cosmic rays.Comment: 5 pages; talk presented at First International Workshop on Radio
Detection of High-Energy Particles (RADHEP-2000), UCLA, Los Angeles November
16-18, 200
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