1,344 research outputs found
The Possible White Dwarf-Neutron Star Connection
The current status of the problem of whether neutron stars can form, in close
binary systems, by accretion-induced collapse (AIC) of white dwarfs is
examined. We find that, in principle, both initially cold C+O white dwarfs in
the high-mass tail of their mass distribution in binaries and O+Ne+Mg white
dwarfs can produce neutron stars. Which fractions of neutron stars in different
types of binaries (or descendants from binaries) might originate from this
process remains uncertain.Comment: 6 pages. To appear in "White Dwarfs", ed. J. Isern, M. Hernanz, and
E. Garcia-Berro (Dordrecht: Kluwer
Production and propagation of heavy hadrons in air-shower simulators
Very energetic charm and bottom hadrons may be produced in the upper
atmosphere when a primary cosmic ray or the leading hadron in an extensive air
shower collide with a nucleon. At GeV their decay length
becomes of the order of 10 km, implying that they tend to interact in the air
instead of decaying. Since the inelasticity in these collisions is much smaller
than the one in proton and pion collisions, there could be rare events where a
heavy-hadron component transports a significant amount of energy deep into the
atmosphere. We have developed a module for the detailed simulation of these
processes and have included it in a new version of the air shower simulator
AIRES. We study the frequency, the energy distribution and the depth of charm
and bottom production, as well as the depth and the energy distribution of
these quarks when they decay. As an illustration, we consider the production
and decay of tau leptons (from decays) and the lepton flux at PeV
energies from a 30 EeV proton primary. The proper inclusion of charm and bottom
hadrons in AIRES opens the possibility to search for air-shower observables
that are sensitive to heavy quark effects.Comment: Accepted for publication in Astroparticle Physic
Photoproduction with a mini-jet model and Cosmic Ray showers
We present post-LHC updates of estimates of the total photo-production cross
section in a mini-jet model with infrared soft gluon resummation, and apply the
model to study Cosmic Ray shower development, comparing the results with those
obtained from other existing models.Comment: 7 pages, 5 figures, presented at Photon 2017, 22-26 May 2017 CER
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