202 research outputs found
Searching for the QCD Axion with Gravitational Microlensing
The phase transition responsible for axion dark matter production can create
large amplitude isocurvature perturbations which collapse into dense objects
known as axion miniclusters. We use microlensing data from the EROS survey, and
from recent observations with the Subaru Hyper Suprime Cam to place constraints
on the minicluster scenario. We compute the microlensing event rate for
miniclusters treating them as spatially extended objects with an extended mass
function. Using the published bounds on the number of microlensing events we
bound the fraction of DM collapsed into miniclusters, . For an
axion with temperature dependent mass consistent with the QCD axion we find
, which represents the first
observational constraint on the minicluster fraction. We forecast that a
high-efficiency observation of ten nights with Subaru would be sufficient to
constrain over the entire QCD axion mass range. We
make various approximations to derive these constraints and dedicated analyses
by the observing teams of EROS and Subaru are necessary to confirm our results.
If accurate theoretical predictions for can be made in future then
microlensing can be used to exclude, or discover, the QCD axion. Further
details of our computations are presented in a companion paper.Comment: 5 pages, 4 figures, v2 contains an improved description of our
modeling of miniclusters and lensing with revised limits, matches version
accepted in PR
Unifying inflation and dark matter with the Peccei-Quinn field: observable axions and observable tensors
A model of high scale inflation is presented where the radial part of the
Peccei-Quinn (PQ) field with a non-minimal coupling to gravity plays the role
of the inflaton, and the QCD axion is the dark matter. A quantum fluctuation of
in the axion field will result in a smaller angular
fluctuation if the PQ field is sitting at a larger radius during inflation than
in the vacuum. This changes the effective axion decay constant, , during
inflation and dramatically reduces the production of isocurvature modes. This
mechanism opens up a new window in parameter space where an axion decay
constant in the range is compatible with observably large . The exact range allowed for
depends on the efficiency of reheating. This model also predicts a
minimum possible value of . The new window can be explored by a
measurement of possible with \textsc{Spider} and the proposed CASPEr
experiment search for high axions.Comment: 7 pages, 4 figure
Factors Influencing the Occurrence of Birds That Use Feeders in Iowa
Since its inception in 1984, data from the annual Iowa Winter Bird Feeder Survey have provided valuable information about birds that use feeders in Iowa such as spatial and temporal population trends. Using data from the 1988 and 1994 Surveys, we examined how the occurrence of bird species that use feeders was influenced by geographic location, the habitat surrounding a house, and the types of seeds offered at a house. Of the 23 species examined, the occurrence of 8 species was influenced by latitude, 22 species were influenced by the habitat surrounding the house, and 22 species were influenced by the presence of water or the types of food available. Two of the more surprising results from this study were that seven species had a positive relationship between occurrence and corn, and only three species had a positive relationship with the presence of mixed seed. Although people interested in feeding birds may not be able to attract all species, results from this study may be used to increase ones likelihood of viewing individual species of interest
PineappleDB: An online pineapple bioinformatics resource
BACKGROUND: A world first pineapple EST sequencing program has been undertaken to investigate genes expressed during non-climacteric fruit ripening and the nematode-plant interaction during root infection. Very little is known of how non-climacteric fruit ripening is controlled or of the molecular basis of the nematode-plant interaction. PineappleDB was developed to provide the research community with access to a curated bioinformatics resource housing the fruit, root and nematode infected gall expressed sequences. DESCRIPTION: PineappleDB is an online, curated database providing integrated access to annotated expressed sequence tag (EST) data for cDNA clones isolated from pineapple fruit, root, and nematode infected root gall vascular cylinder tissues. The database currently houses over 5600 EST sequences, 3383 contig consensus sequences, and associated bioinformatic data including splice variants, Arabidopsis homologues, both MIPS based and Gene Ontology functional classifications, and clone distributions. The online resource can be searched by text or by BLAST sequence homology. The data outputs provide comprehensive sequence, bioinformatic and functional classification information. CONCLUSION: The online pineapple bioinformatic resource provides the research community with access to pineapple fruit and root/gall sequence and bioinformatic data in a user-friendly format. The search tools enable efficient data mining and present a wide spectrum of bioinformatic and functional classification information. PineappleDB will be of broad appeal to researchers investigating pineapple genetics, non-climacteric fruit ripening, root-knot nematode infection, crassulacean acid metabolism and alternative RNA splicing in plants
Colored Group Field Theory
Group field theories are higher dimensional generalizations of matrix models.
Their Feynman graphs are fat and in addition to vertices, edges and faces, they
also contain higher dimensional cells, called bubbles. In this paper, we
propose a new, fermionic Group Field Theory, posessing a color symmetry, and
take the first steps in a systematic study of the topological properties of its
graphs. Unlike its bosonic counterpart, the bubbles of the Feynman graphs of
this theory are well defined and readily identified. We prove that this graphs
are combinatorial cellular complexes. We define and study the cellular homology
of this graphs. Furthermore we define a homotopy transformation appropriate to
this graphs. Finally, the amplitude of the Feynman graphs is shown to be
related to the fundamental group of the cellular complex
Spectral Measures and Generating Series for Nimrep Graphs in Subfactor Theory II: SU(3)
We complete the computation of spectral measures for SU(3) nimrep graphs
arising in subfactor theory, namely the SU(3) ADE graphs associated with SU(3)
modular invariants and the McKay graphs of finite subgroups of SU(3). For the
SU(2) graphs the spectral measures distill onto very special subsets of the
semicircle/circle, whilst for the SU(3) graphs the spectral measures distill
onto very special subsets of the discoid/torus. The theory of nimreps allows us
to compute these measures precisely. We have previously determined spectral
measures for some nimrep graphs arising in subfactor theory, particularly those
associated with all SU(2) modular invariants, all subgroups of SU(2), the
torus, SU(3), and some SU(3) graphs.Comment: 38 pages, 21 figure
Discrete and continuum third quantization of Gravity
We give a brief introduction to matrix models and the group field theory
(GFT) formalism as realizations of the idea of a third quantization of gravity,
and present in some more detail the idea and basic features of a continuum
third quantization formalism in terms of a field theory on the space of
connections, building up on the results of loop quantum gravity that allow to
make the idea slightly more concrete. We explore to what extent one can
rigorously define such a field theory. Concrete examples are given for the
simple case of Riemannian GR in 3 spacetime dimensions. We discuss the relation
between GFT and this formal continuum third quantized gravity, and what it can
teach us about the continuum limit of GFTs.Comment: 21 pages, 5 eps figures; submitted as a contribution to the
proceedings of the conference "Quantum Field Theory and Gravity Conference
Regensburg 2010" (28 September - 1 October 2010, Regensburg/Bavaria); v2:
preprint number include
Flavor Unification and Discrete Nonabelian Symmetries
Grand unified theories with fermions transforming as irreducible
representations of a discrete nonabelian flavor symmetry can lead to realistic
fermion masses, without requiring very small fundamental parameters. We
construct a specific example of a supersymmetric GUT based on the flavor
symmetry --- a subgroup of --- which can explain the
observed quark and lepton masses and mixing angles. The model predicts
and gives a neutrino mass eV, with other neutrino masses much lighter. Combined
constraints of light quark masses and perturbative unification place flavor
symmetry breaking near the GUT scale; it may be possible to probe these
extremely high energies by continuing the search for flavor changing neutral
currents.Comment: 24 pages, UCSD-PTH-93-30 (uuencoded file; requires epsf.tex,
available from this bulletin board
Abelian Hidden Sectors at a GeV
We discuss mechanisms for naturally generating GeV-scale hidden sectors in
the context of weak-scale supersymmetry. Such low mass scales can arise when
hidden sectors are more weakly coupled to supersymmetry breaking than the
visible sector, as happens when supersymmetry breaking is communicated to the
visible sector by gauge interactions under which the hidden sector is
uncharged, or if the hidden sector is sequestered from gravity-mediated
supersymmetry breaking. We study these mechanisms in detail in the context of
gauge and gaugino mediation, and present specific models of Abelian GeV-scale
hidden sectors. In particular, we discuss kinetic mixing of a U(1)_x gauge
force with hypercharge, singlets or bi-fundamentals which couple to both
sectors, and additional loop effects. Finally, we investigate the possible
relevance of such sectors for dark matter phenomenology, as well as for low-
and high-energy collider searches.Comment: 43 pages, no figures; v2: to match JHEP versio
The complete 1/N expansion of colored tensor models in arbitrary dimension
In this paper we generalize the results of [1,2] and derive the full 1/N
expansion of colored tensor models in arbitrary dimensions. We detail the
expansion for the independent identically distributed model and the topological
Boulatov Ooguri model
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