172 research outputs found
Studying Exotic Hadrons in Heavy Ion Collisions
We investigate the possibilities of using measurements in present and future
experiments on heavy ion collisions to answer some longstanding problems in
hadronic physics, namely identifying hadronic molecular states and exotic
hadrons with multiquark components. The yields of a selected set of exotic
hadron candidates in relativistic heavy ion collisions are discussed in the
coalescence model in comparison with the statistical model. We find that the
yield of a hadron is typically an order of magnitude smaller when it is a
compact multiquark state, compared to that of an excited hadronic state with
normal quark numbers. We also find that some loosely bound hadronic molecules
are formed more abundantly than the statistical model prediction by a factor of
two or more. Moreover, due to the significant numbers of charm and bottom
quarks produced at RHIC and even larger numbers expected at LHC, some of the
proposed heavy exotic hadrons could be produced with sufficient abundance for
detection, making it possible to study these new exotic hadrons in heavy ion
collisions.Comment: 18 pages, 2 figure
Alfven Wave-Driven Proto-Neutron Star Winds And R-Process Nucleosynthesis
We propose magnetic proto-neutron star (PNS) winds driven by \Alfven waves as
well as the neutrino heating as an appropriate site for the r-process
nucleosynthesis. \Alfven waves excited by surface motions of a PNS propagate
outwardly, and they heat and accelerate the wind by dissipation. Compared with
the wind purely driven by the neutrino heating, larger entropy per baryon and
shorter dynamical time scale are achieved, which favors the r-process. We study
reasonable cases that a wave amplitude is 10% of \Alfven speed at the surface
to find that a PNS with surface field strength, G,
gives suitable wind properties for the r-process, provided that dissipation
length of the wave is at most 10 times of the PNS radius. We also
compare properties of transcritical and subcritical winds in light of the
r-process. We finally discuss possibilities of detections of -rays from
radioactive nuclei and absorption lines due to Ba in supernova remnants which
possess magnetars.Comment: 14 pages, including 4 figures, ApJ, in pres
Building genomic infrastructure: Sequencing platinum-standard reference-quality genomes of all cetacean species.
International audienc
Why sequence all eukaryotes?
Life on Earth has evolved from initial simplicity to the astounding complexity we experience today. Bacteria and archaea have largely excelled in metabolic diversification, but eukaryotes additionally display abundant morphological innovation. How have these innovations come about and what constraints are there on the origins of novelty and the continuing maintenance of biodiversity on Earth? The history of life and the code for the working parts of cells and systems are written in the genome. The Earth BioGenome Project has proposed that the genomes of all extant, named eukaryotes-about 2 million species-should be sequenced to high quality to produce a digital library of life on Earth, beginning with strategic phylogenetic, ecological, and high-impact priorities. Here we discuss why we should sequence all eukaryotic species, not just a representative few scattered across the many branches of the tree of life. We suggest that many questions of evolutionary and ecological significance will only be addressable when whole-genome data representing divergences at all of the branchings in the tree of life or all species in natural ecosystems are available. We envisage that a genomic tree of life will foster understanding of the ongoing processes of speciation, adaptation, and organismal dependencies within entire ecosystems. These explorations will resolve long-standing problems in phylogenetics, evolution, ecology, conservation, agriculture, bioindustry, and medicine
- …