12,186 research outputs found
Vacuum Stability and the Higgs Boson
The discovery of the Higgs boson at the LHC, and especially the determination
of its mass around 125 GeV, together with the absence of any trace of new
physics make it conceivable that we live in a metastable (but long-lived)
electroweak vacuum. I will describe the state-of-the-art calculation that leads
to this conclusion, elaborate on possible implications as well as cures of this
instability of the Higgs potential and discuss some possible lines of attack
for lattice studies of such metastability.Comment: 15 pages. Proceedings of the 31st International Symposium on Lattice
Field Theory - LATTICE 201
Electroweak Baryogenesis with Cosmic Strings ?
I report on a critical analysis of the scenario of electroweak baryogenesis
mediated by nonsuperconducting cosmic strings. This mechanism relies upon
electroweak symmetry restoration in a region around cosmic strings, where
sphalerons would be unsuppressed. I discuss the various problems this scenario
has to face, presenting a careful computation of the sphaleron rates inside the
strings, of the chemical potential for chiral number and of the efficiency of
baryogenesis in different regimes of string networks. The conclusion is that
the asymmetry in baryon number generated by this scenario is smaller than the
observed value by at least 10 orders of magnitude.Comment: 5 pages, uses sprocl.sty. Talk given at SEWM98, Dec.98, Copenhage
A Fresh Look at the Calculation of Tunneling Actions including Gravitational Effects
Recently, the calculation of tunneling actions, that control the exponential
suppression of the decay of metastable vacua, has been reformulated as an
elementary variational problem in field space. This paper extends this
formalism to include the effect of gravity. Considering tunneling potentials
that go from the false vacuum to some on the
stable basin of the scalar potential , the tunneling action is the
minimum of the functional , where , and is the reduced
Planck mass. This one-line simple result applies equally to AdS, Minkowski or
dS vacua decays and reproduces the Hawking-Moss action in the appropriate
cases. This formalism provides new handles for the theoretical understanding of
different features of vacuum decay in the presence of gravity.Comment: 12 pages in double-column format. 8 figures. Small changes, errata
fixe
Resummation of Goldstone Infrared Divergences: A Proof to All Orders
The perturbative effective potential calculated in Landau gauge suffers from
infrared problems due to Goldstone boson loops. These divergences are spurious
and can be removed by a resummation procedure that amounts to a shift of the
mass of soft Goldstones. We prove this to all loops using an effective theory
approach, providing a compact recipe for the shift of the Goldstone mass that
relies on the use of the method of regions to split soft and hard Goldstone
contributions.Comment: 30 pages, 3 figure
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