13,089 research outputs found
Photometry of 40 LMC Cepheids
We present V and I_c CCD photometry for 40 LMC Cepheids at 1 to 3 epochs.
This represents a significant increase in the number of LMC Cepheids with
-band data, and, as we show, is a useful addition to the sample which can be
used to calibrate the period--luminosity relations in these important bands
An AdS/QCD holographic wavefunction for the rho meson and diffractive rho meson electroproduction
We show that AdS/QCD generates predictions for the rate of diffractive rho
meson electroproduction that are in agreement with data collected at the HERA
electron-proton collider.Comment: 9 pages, 4 figures. Figure 3 added to illustrate that the AdS/QCD
prediction is impressive. Accepted for publication in Physical Review Letter
Neutral kaon mixing beyond the standard model with nf=2+1 chiral fermions
We compute the hadronic matrix elements of the four-quark operators needed
for the study of neutral kaon mixing beyond the Standard Model (SM). We use
nf=2+1 flavours of domain-wall fermions (DWF) which exhibit good chiral-flavour
symmetry. The renormalization is performed non-perturbatively through the
RI-MOM scheme and our results are converted perturbatively to MSbar. The
computation is performed on a single lattice spacing a=0.086 fm with a lightest
unitary pion mass of 290 MeV. The various systematic errors, including the
discretisation effects, are estimated and discussed. Our results confirm a
previous quenched study, where large ratios of non-SM to SM matrix elements
were obtained.Comment: 5 pages, 4 figures, 1 table. v2 paper version, R3 and B3 corrected,
conversion to 2GeV added, references adde
Detecting the signatures of helium in type Iax supernovae
Recent studies have argued that the progenitor system of type Iax supernovae
must consist of a carbon-oxygen white dwarf accreting from a helium star
companion. Based on existing explosion models invoking the pure deflagration of
carbon-oxygen white dwarfs, we investigate the likelihood of producing spectral
features due to helium in type Iax supernovae. From this scenario, we select
those explosion models producing ejecta and Ni masses that are broadly
consistent with those estimated for type Iax supernovae (0.014 -
0.478~ and - 0.183~, respectively). To this
end, we present a series of models of varying luminosities (~mag) with helium abundances accounting for up to
36\% of the ejecta mass, and covering a range of epochs beginning a few
days before Bband maximum to approximately two weeks after maximum. We find
that the best opportunity for detecting \ion{He}{i} features is at
near-infrared wavelengths, and in the post-maximum spectra of the fainter
members of this class. We show that the optical spectrum of SN~2007J is
potentially consistent with a large helium content (a few 10),
but argue that current models of accretion and material stripping from a
companion struggle to produce compatible scenarios. We also investigate the
presence of helium in all objects with near-infrared spectra. We show that
SNe~2005hk, 2012Z, and 2015H contain either no helium or their helium
abundances are constrained to much lower values
(10). Our results demonstrate the differences in
helium content among type Iax supernovae, perhaps pointing to different
progenitor channels. Either SN~2007J is an outlier in terms of its progenitor
system, or it is not a true member of the type Iax supernova class.Comment: 15 pages, 12 figures, 2 tables. Accepted for publication in Astronomy
and Astrophysic
Exploring the relationship between family migration and social stratification through the investigation of women's labour market experiences in contemporary Britain
Fourier-based Function Secret Sharing with General Access Structure
Function secret sharing (FSS) scheme is a mechanism that calculates a
function f(x) for x in {0,1}^n which is shared among p parties, by using
distributed functions f_i:{0,1}^n -> G, where G is an Abelian group, while the
function f:{0,1}^n -> G is kept secret to the parties. Ohsawa et al. in 2017
observed that any function f can be described as a linear combination of the
basis functions by regarding the function space as a vector space of dimension
2^n and gave new FSS schemes based on the Fourier basis. All existing FSS
schemes are of (p,p)-threshold type. That is, to compute f(x), we have to
collect f_i(x) for all the distributed functions. In this paper, as in the
secret sharing schemes, we consider FSS schemes with any general access
structure. To do this, we observe that Fourier-based FSS schemes by Ohsawa et
al. are compatible with linear secret sharing scheme. By incorporating the
techniques of linear secret sharing with any general access structure into the
Fourier-based FSS schemes, we show Fourier-based FSS schemes with any general
access structure.Comment: 12 page
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