323 research outputs found
SUSY breaking after inflation in supergravity with inflaton in a massive vector multiplet
We propose a limited class of models, describing interacting chiral
multiplets with a non-minimal coupling to a vector multiplet, in curved
superspace of supergravity. Those models are suitable for the
inflationary model building in supergravity with inflaton assigned to a massive
vector multiplet and spontaneous SUSY breaking in Minkowski vacuum after
inflation, for any values of the inflationary parameters and , and any
scale of SUSY breaking.Comment: 9 pages, no figures, LaTeX2e; minor corrections, two references
added, misprints correcte
Cosmological imprints of string axions in plateau
We initiate a study on various cosmological imprints of string axions whose
scalar potentials have plateau regions. In such cases, we show that a delayed
onset of oscillation generically leads to a parametric resonance instability.
In particular, for ultralight axions, the parametric resonance can enhance the
power spectrum slightly below the Jeans scale, alleviating the tension with the
Lyman forest observations. We also argue that a long-lasting resonance
can lead to an emission of gravitational waves at the frequency bands which are
detectable by gravitational wave interferometers and pulsar timing arrays.Comment: 5 pages, 5 figures; v2: references added, v3: matches with the
published versio
Genotypic status of the TbAT1/P2 adenosine transporter of Trypanosoma brucei gambiense isolates from northwestern Uganda following melarsoprol withdrawal
Human African trypanosomiasis (HAT) manifests as a chronic infection caused by <i>Trypanosoma brucei gambiense</i>, or as a more acute form due to <i>T. b. rhodesiense</i>. Both manifestations occur in Uganda and melarsoprol use against the former was jeopardised in the 1990s as reports of reduced efficacy increased to the point where it was dismissed as first-line treatment at some treatment centers. Previous work to elucidate possible mechanisms leading to melarsoprol resistance pointed to a P2 type adenosine transporter known to mediate melarsoprol uptake and previously shown to be mutated in significant numbers of patients not responding to the drug. Our present findings indicate that there is a low prevalence of mutants in foci where melarsoprol relapses are infrequent. In addition we observe that at the Omugo focus where the drug was withdrawn as first line over 6 years ago, the mutant alleles have disappeared, suggesting that drug pressure is responsible for fuelling their spread. Thus constant monitoring for mutants could play a key role in cost-effective HAT management by identifying which foci can still use the less logistically demanding melarsoprol as opposed to the alternative drug eflornithine. What is required now is a simple method for identifying such mutants at the point of care, enabling practitioners to make informed prescriptions at first diagnosis
Complete On-Shell Renormalization Scheme for the Minimal Supersymmetric Higgs Sector
Systematic on-shell renormalization programme is carried out for the Higgs
and gauge boson sectors of the Minimal Supersymmetric Standard Model. Complete
1-loop results for the 2- and 3-point Green's functions are explicitly given.
The Higgs boson masses and the cross sections for the neutral scalar production
in the colliders are calculated.Comment: 64 pages, 10 figures (not included, availaible on request in
PostScript format), LaTeX, preprint no MPI-Ph/92-117 and DFPD 93/TH/1
Planetary Nebulae in the Small Magellanic Cloud
We analyse the planetary nebulae (PNe) population of the Small Magellanic
Cloud (SMC), based on evolutionary models of stars with metallicities in the
range and mass , evolved through the asymptotic giant branch (AGB) phase. The models
used account for dust formation in the circumstellar envelope. To characterise
the PNe sample of the SMC, we compare the observed abundances of the various
species with the final chemical composition of the AGB models: this study
allows us to identify the progenitors of the PNe observed, in terms of mass and
chemical composition. According to our interpretation, most of the PNe descend
from low-mass () stars, which become carbon rich, after
experiencing repeated third dredge-up episodes, during the AGB phase. A
fraction of the PNe showing the signature of advanced CNO processing are
interpreted as the progeny of massive AGB stars, with mass above , undergoing strong hot bottom burning. The differences with the
chemical composition of the PNe population of the Large Magellanic Cloud (LMC)
is explained on the basis of the diverse star formation history and
age-metallicity relation of the two galaxies. The implications of the present
study for some still highly debated points regarding the AGB evolution are also
commented.Comment: Accepted for publication in MNRAS, 11 pages, 4 figure
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