1,040 research outputs found
Higgs inflation: consistency and generalisations
We analyse the self-consistency of inflation in the Standard Model, where the
Higgs field has a large non-minimal coupling to gravity. We determine the
domain of energies in which this model represents a valid effective field
theory as a function of the background Higgs field. This domain is bounded
above by the cutoff scale which is found to be higher than the relevant
dynamical scales throughout the whole history of the Universe, including the
inflationary epoch and reheating. We present a systematic scheme to take into
account quantum loop corrections to the inflationary calculations within the
framework of effective field theory. We discuss the additional assumptions that
must be satisfied by the ultra-violet completion of the theory to allow
connection between the parameters of the inflationary effective theory and
those describing the low-energy physics relevant for the collider experiments.
A class of generalisations of inflationary theories with similar properties is
constructed.Comment: 25 pages, 1 figur
Hyperon production asymmetries in 500 GeV/c pion nucleus interactions
We present a preliminary study from Fermilab experiment E791 of Lambda^0 /
Lambda^0 bar, Xi^- / Xi^+ and Omega^- /Omega^+ production asymmetries from pi^-
nucleus interactions at 500 Gev/c. The production asymmetries for these
particles are studied as a function of x_F and pt^2. We observed an asymmetry
in the target fragmentation region for Lambda^0's larger than that for Xi's,
suggesting diquark effects. The asymmetry for Omega's is significatively
smaller than for the other two hyperons consistent with the fact that Omega's
do not share valence quarks with either the pion or the target particle. In the
beam fragmentation region, the asymmetry tends to 0.1 for both Lambda^0's and
Xi's. The asymmetries vs pt^2 are approximately constant for the three strange
baryons under study.Comment: Typos correcte
Spin Resistivity in the Frustrated Model
We study in this paper the resistivity encountered by Ising itinerant spins
traveling in the so-called frustrated simple cubic Ising lattice. For
the lattice, we take into account the interactions between nearest-neighbors
and next-nearest-neighbors, and respectively. Itinerant spins
interact with lattice spins via a distance-dependent interaction. We also take
into account an interaction between itinerant spins. The lattice is frustrated
in a range of in which we show that it undergoes a very strong
first-order transition. Using Monte Carlo simulation, we calculate the
resistivity of the itinerant spins and show that the first-order
transition of the lattice causes a discontinuity of .Comment: submitted for publicatio
The Charm of the Proton and the Production
We propose a two component model for charmed baryon production in
collisions consisting of the conventional parton fusion mechanism and
fragmentation plus quarks recombination in which a valence diquark from
the proton recombines with a -sea quark to produce a . Our
two-component model is compared with the intrinsic charm two-component model
and experimental data.Comment: 6 pages, LaTex, 2 figures included, aipproc.sty included. Talk
presented at Simposio Latino Americano de Fisica de Altas Energias, Merida,
Mexico, November 199
Asymmetry studies in Lambda 0/Lambda 0-bar, Xi-/Xi+ and Omega-/Omega+ production
We present a study on hyperon/anti-hyperon production asymmetries in the
framework of the recombination model. The production asymmetries for Lambda
0/Lambda 0-bar, Xi-/Xi+ and Omega-/Omega+ are studied as a function of x_F.
Predictions of the model are compared to preliminary data on
hyperon/anti-hyperon production asymmetries in 500 GeV/c pi- p interactions
from the Fermilab E791 experiment. The model predicts a growing asymmetry with
the number of valence quarks shared by the target and the produced hyperons in
the x_F < 0 region. In the positive x_F region, the model predicts constant
asymmetries for Lambda 0/Lambda 0-bar and Omega-/Omega+ production and a
growing asymmetry with x_F for Xi-/Xi+. We found a qualitatively good agreement
between the model predictions and data, showing that recombination is a
competitive mechanism in the hadronization process.Comment: One reference correcte
Spin Resistivity in Frustrated Antiferromagnets
In this paper we study the spin transport in frustrated antiferromagnetic FCC
films by Monte Carlo simulation. In the case of Ising spin model, we show that
the spin resistivity versus temperature exhibits a discontinuity at the phase
transition temperature: an upward jump or a downward fall, depending on how
many parallel and antiparallel localized spins interacting with a given
itinerant spin. The surface effects as well as the difference of two degenerate
states on the resistivity are analyzed. Comparison with non frustrated
antiferromagnets is shown to highlight the frustration effect. We also show and
discuss the results of the Heisenberg spin model on the same lattice
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