1,291,092 research outputs found
The minimal volume orientable hyperbolic 2-cusped 3-manifolds
We prove that the Whitehead link complement and the (-2, 3, 8) pretzel link
complement are the minimal volume orientable hyperbolic 3-manifolds with two
cusps, with volume 3.66... = 4 x Catalan's constant. We use topological
arguments to establish the existence of an essential surface which provides a
lower bound on volume and strong constraints on the manifolds that realize that
lower bound.Comment: 10 pages, 5 figures, incorporated referees comments, includes
hyperref link
Figures of merit for present and future dark energy probes
We compare current and forecasted constraints on dynamical dark energy models
from Type Ia supernovae and the cosmic microwave background using figures of
merit based on the volume of the allowed dark energy parameter space. For a
two-parameter dark energy equation of state that varies linearly with the scale
factor, and assuming a flat universe, the area of the error ellipse can be
reduced by a factor of ~10 relative to current constraints by future
space-based supernova data and CMB measurements from the Planck satellite. If
the dark energy equation of state is described by a more general basis of
principal components, the expected improvement in volume-based figures of merit
is much greater. While the forecasted precision for any single parameter is
only a factor of 2-5 smaller than current uncertainties, the constraints on
dark energy models bounded by -1<w<1 improve for approximately 6 independent
dark energy parameters resulting in a reduction of the total allowed volume of
principal component parameter space by a factor of ~100. Typical quintessence
models can be adequately described by just 2-3 of these parameters even given
the precision of future data, leading to a more modest but still significant
improvement. In addition to advances in supernova and CMB data, percent-level
measurement of absolute distance and/or the expansion rate is required to
ensure that dark energy constraints remain robust to variations in spatial
curvature.Comment: 9 pages, 7 figures; submitted to Phys. Rev.
S-parameter and vector decay constant in QCD with eight fundamental fermions
SU(3) gauge theory with eight massless fundamental fermions seems to be near
the conformal boundary, and is a candidate theory of walking technicolor. Along
the series of study by LatKMI collaboration using HISQ fermions, S-parameter
and vector decay constant, which provide important constraints in the model of
electroweak symmetry breaking, are calculated for this theory. Use of various
volumes allows a systematic investigation of finite volume effects. A strong
sensitivity of the S-parameter to the volume is found.Comment: 7 pages, 7 figures, Proceedings of the 33rd International Symposium
on Lattice Field Theory, July 14-18, 2015, Kobe, Japa
Relativistic Mean-Field Hadronic Models under Nuclear Matter Constraints
Relativistic mean-field (RMF) models have been widely used in the study of
many hadronic frameworks because of several important aspects not always
present in nonrelativistic models, such as intrinsic Lorentz covariance,
automatic inclusion of spin, appropriate saturation mechanism for nuclear
matter, causality and, therefore, no problems related to superluminal speed of
sound. With the aim of identifying the models which best satisfy well known
properties of nuclear matter, we have analyzed parameterizations of seven
different types of RMF models under three different sets of constraints related
to symmetric nuclear matter, pure neutron matter, symmetry energy, and its
derivatives. One of these (SET1) is formed of the same constraints used in a
recent work [M. Dutra et al., Phys. Rev. C 85, 035201 (2012)] in which we
analyzed Skyrme parameterizations. The results pointed to models
consistent with all constraints. By using another set of constraints, namely,
SET2a, formed by the updated versions of the previous one, we found models
approved simultaneously. Finally, in the third set, named SET2b, in which the
values of the constraints are more restrictive, we found consistent models.
Another interesting feature of our analysis is that the results change
dramatically if we do not consider the constraint regarding the volume part of
the isospin incompressibility (). In this case, we have
approved models in SET2a and in SET2b.Comment: 63 pages, 3 figures and 9 tables. Version accepted for publication in
PR
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