267 research outputs found
Particle physics models of inflation
Inflation models are compared with observation on the assumption that the
curvature perturbation is generated from the vacuum fluctuation of the inflaton
field. The focus is on single-field models with canonical kinetic terms,
classified as small- medium- and large-field according to the variation of the
inflaton field while cosmological scales leave the horizon. Small-field models
are constructed according to the usual paradigm for beyond Standard Model
physicsComment: Based on a talk given at the 22nd IAP Colloquium, ``Inflation +25'',
Paris, June 2006 Curve omitted from final Figur
Gauged Inflation
We propose a model for cosmic inflation which is based on an effective
description of strongly interacting, nonsupersymmetric matter within the
framework of dynamical Abelian projection and centerization. The underlying
gauge symmetry is assumed to be with . Appealing to a
thermodynamical treatment, the ground-state structure of the model is
classically determined by a potential for the inflaton field (dynamical
monopole condensate) which allows for nontrivially BPS saturated and thereby
stable solutions. For this leads to decoupling of gravity from the
inflaton dynamics. The ground state dynamics implies a heat capacity for the
vacuum leading to inflation for temperatures comparable to the mass scale
of the potential. The dynamics has an attractor property. In contrast to the
usual slow-roll paradigm we have during inflation. As a consequence,
density perturbations generated from the inflaton are irrelevant for the
formation of large-scale structure, and the model has to be supplemented with
an inflaton independent mechanism for the generation of spatial curvature
perturbations. Within a small fraction of the Hubble time inflation is
terminated by a transition of the theory to its center symmetric phase. The
spontaneously broken symmetry stabilizes relic vector bosons in the
epochs following inflation. These heavy relics contribute to the cold dark
matter of the universe and potentially originate the UHECRs beyond the GZK
bound.Comment: 23 pages, 4 figures, subsection added, revision of text, to app. in
PR
Nosology of genetic skeletal disorders: 2023 revision.
The "Nosology of genetic skeletal disorders" has undergone its 11th revision and now contains 771 entries associated with 552 genes reflecting advances in molecular delineation of new disorders thanks to advances in DNA sequencing technology. The most significant change as compared to previous versions is the adoption of the dyadic naming system, systematically associating a phenotypic entity with the gene it arises from. We consider this a significant step forward as dyadic naming is more informative and less prone to errors than the traditional use of list numberings and eponyms. Despite the adoption of dyadic naming, efforts have been made to maintain strong ties to the MIM catalog and its historical data. As with the previous versions, the list of disorders and genes in the Nosology may be useful in considering the differential diagnosis in the clinic, directing bioinformatic analysis of next-generation sequencing results, and providing a basis for novel advances in biology and medicine
Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events
The - oscillation frequency has been measured with a sample of
23 million \B\bar B pairs collected with the BABAR detector at the PEP-II
asymmetric B Factory at SLAC. In this sample, we select events in which both B
mesons decay semileptonically and use the charge of the leptons to identify the
flavor of each B meson. A simultaneous fit to the decay time difference
distributions for opposite- and same-sign dilepton events gives ps.Comment: 7 pages, 1 figure, submitted to Physical Review Letter
Galaxy Clusters Associated with Short GRBs. II. Predictions for the Rate of Short GRBs in Field and Cluster Early-Type Galaxies
We determine the relative rates of short GRBs in cluster and field early-type
galaxies as a function of the age probability distribution of their
progenitors, P(\tau) \propto \tau^n. This analysis takes advantage of the
difference in the growth of stellar mass in clusters and in the field, which
arises from the combined effects of the galaxy stellar mass function, the
early-type fraction, and the dependence of star formation history on mass and
environment. This approach complements the use of the early- to late-type host
galaxy ratio, with the added benefit that the star formation histories of
early-type galaxies are simpler than those of late-type galaxies, and any
systematic differences between progenitors in early- and late-type galaxies are
removed. We find that the ratio varies from R(cluster)/R(field) ~ 0.5 for n =
-2 to ~ 3 for n = 2. Current observations indicate a ratio of about 2,
corresponding to n ~ 0 - 1. This is similar to the value inferred from the
ratio of short GRBs in early- and late-type hosts, but it differs from the
value of n ~ -1 for NS binaries in the Milky Way. We stress that this general
approach can be easily modified with improved knowledge of the effects of
environment and mass on the build-up of stellar mass, as well as the effect of
globular clusters on the short GRB rate. It can also be used to assess the age
distribution of Type Ia supernova progenitors.Comment: ApJ accepted versio
Measurement of the CP-Violating Asymmetry Amplitude sin2
We present results on time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 88 million Y(4S) --> B Bbar decays collected between 1999 and 2002 with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We study events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the other B meson is determined to be either a B0 or B0bar from its decay products. The amplitude of the CP-violating asymmetry, which in the Standard Model is proportional to sin2beta, is derived from the decay-time distributions in such events. We measure sin2beta = 0.741 +/- 0.067 (stat) +/- 0.033 (syst) and |lambda| = 0.948 +/- 0.051 (stat) +/- 0.017 (syst). The magnitude of lambda is consistent with unity, in agreement with the Standard Model expectation of no direct CP violation in these modes
Use of secondary forests by understory birds in a fragmented landscape in central Amazonia
Rates of deforestation in the Brazilian Amazon have increased since 1991 and forecasts are not optimistic about the slowing of this process. Some authors believe that the Amazon may be experiencing a massive process of species extinction. However, the deforestation is accompanied by the expansion of secondary forests that are established in the abandoned areas. The trend is an increase in secondary forests cover, resulting in a mosaic of primary forest (FP) and fragments separated by an array of secondary forests (FS). In this scenario, the prediction of a massive extinction could be wrong if many species could survive in the secondary forests. To assess the importance of FS for the understory birds we sampled areas in regeneration and a continuous forest of a fragmented landscape. We conducted mist netting (24 nets/day) for six consecutive days/month, for 8 months (May-November) in 2009. Some forest species as do not seem to be adapted to the secondary forest environment and their occurrences are restricted to continuous forest environments. But most focal species showed no significant difference in apparent survival rates between the enviroments, suggesting that these species inhabit the secondary forest and the primary forest similarly. Because most of the matrix in fragmented landscapes are composed by secondary forests, such results highlights the conservation value that these habitats present in the long term. Thus, FS should be regarded as dynamic matrix that not only allows the movement of individuals but also function as habitat for many species typical of FP.Na Amazônia, as taxas de desmatamento crescem desde 1991 e as previsões não são otimistas quanto à desaceleração desse processo. A devastação da floresta é acompanhada de uma expansão de florestas secundárias (FS) que se estabelecem nas áreas abandonadas. A tendência é um aumento de florestas secundárias, resultando num mosaico de floresta contínua e fragmentos separados por uma matriz de FS. Nesse cenário, autores acreditam que a Amazônia pode passar por um processo massivo de extinção de espécies. Por outro lado, a previsão de um processo massivo de extinção pode ser equivocada, pois muitas espécies florestais poderiam sobreviver nas florestas secundárias. Para avaliar o valor das florestas secundárias para espécies florestais amostramos por oito meses com redes de neblina uma capoeira (FS) em regeneração e uma floresta primária (FP) de uma paisagem fragmentada. Algumas espécies não foram capturadas na capoeira e aparentemente evitam esse tipo de hábitat. No entanto, a maioria das espécies do grupo focal não apresentou diferença na sobrevivência aparente entre os ambientes, o que nos indica que estão habitando a capoeira e a floresta primária da mesma forma. Na realidade amazônica, onde grande parte da matriz é composta por floresta secundária, a matriz tem valor para conservação e deve ser analisada como um elemento dinâmico que não apenas permite a movimentação de indivíduos, mas também serve de hábitat para muitas espécies de floresta primária. Mas ressaltamos que é fundamental a preservação de áreas de floresta primária que servirão de fonte às florestas secundárias adjacentes
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