88,214 research outputs found
In Defense of the Epistemic Imperative
Sample (2015) argues that scientists ought not to believe that their theories are true because they cannot fulfill the epistemic obligation to take the diachronic perspective on their theories. I reply that Sample’s argument imposes an inordinately heavy epistemic obligation on scientists, and that it spells doom not only for scientific theories but also for observational beliefs and philosophical ideas that Samples endorses. I also delineate what I take to be a reasonable epistemic obligation for scientists. In sum, philosophers ought to impose on scientists only an epistemic standard that they are willing to impose on themselves
States near Dirac points of rectangular graphene dot in a magnetic field
In neutral graphene dots the Fermi level coincides with the Dirac points. We
have investigated in the presence of a magnetic field several unusual
properties of single electron states near the Fermi level of such a
rectangular-shaped graphene dot with two zigzag and two armchair edges. We find
that a quasi-degenerate level forms near zero energy and the number of states
in this level can be tuned by the magnetic field. The wavefunctions of states
in this level are all peaked on the zigzag edges with or without some weight
inside the dot. Some of these states are magnetic field-independent surface
states while the others are field-dependent. We have found a scaling result
from which the number of magnetic field-dependent states of large dots can be
inferred from those of smaller dots.Comment: Physical review B in pres
Singlet portal extensions of the standard seesaw models to dark sector with local dark symmetry: An alternative to the new minimal standard model
Assuming dark matter is absolutely stable due to unbroken dark gauge symmetry
and singlet operators are portals to the dark sector, we present a simple
extension of the standard seesaw model that can accommodate all the
cosmological observations as well as terrestrial experiments available as of
now, including leptogenesis, extra dark radiation of (resulting in
the effective number of neutrino species), Higgs
inflation, small and large scale structure formation, and current relic density
of scalar DM (). The Higgs signal strength is equal to one as in the SM for
unbroken case with a scalar dark matter, but it could be less than one
independent of decay channels if the dark matter is a dark sector fermion or if
is spontaneously broken, because of a mixing with a new neutral scalar
boson in the models.Comment: Presented at the 9th PATRAS Workshop on Axions, WIMPs and WISP
Does Scientific Progress Consist in Increasing Knowledge or Understanding?
Bird argues that scientific progress consists in increasing knowledge. Dellsén objects that increasing knowledge is neither necessary nor sufficient for scientific progress, and argues that scientific progress rather consists in increasing understanding. Dellsén also contends that unlike Bird’s view, his view can account for the scientific practices of using idealizations and of choosing simple theories over complex ones. I argue that Dellsén’s criticisms against Bird’s view fail, and that increasing understanding cannot account for scientific progress, if acceptance, as opposed to belief, is required for scientific understanding
Bounded Gaps Between Products of Distinct Primes
Let be an integer. We adapt the Maynard-Tao sieve to produce the
asymptotically best-known bounded gaps between products of distinct primes.
Our result applies to positive-density subsets of the primes that satisfy
certain equidistribution conditions. This improves on the work of Thorne and
Sono
The Solar pp and hep Processes in Effective Field Theory
The strategy of modern effective field theory is exploited to pin down
accurately the flux factors for the and processes in the Sun.
The technique used is to combine the high accuracy established in few-nucleon
systems of the "standard nuclear physics approach" (SNPA) and the systematic
power counting of chiral perturbation theory (ChPT) into a consistent effective
field theory framework. Using highly accurate wave functions obtained in the
SNPA and working to \nlo3 in the chiral counting for the current, we make
totally parameter-free and error-controlled predictions for the and
processes in the Sun.Comment: 5 pages, aipproc macros are included. Talk given at International
Nuclear Physics Conference 2001, Berkeley, California, July 30 - August 3,
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