48,942 research outputs found
Dyonic (A)dS Black Holes in Einstein-Born-Infeld Theory in Diverse Dimensions
We study Einstein-Born-Infeld gravity and construct the dyonic (A)dS planar
black holes in general even dimensions, that carry both the electric charge and
magnetic fluxes along the planar space. In four dimensions, the solution can be
constructed with also spherical and hyperbolic topologies. We study the black
hole thermodynamics and obtain the first law. We also classify the singularity
structure.Comment: Latex, 21 pages, typos corrected and references adde
Godel Metrics with Chronology Protection in Horndeski Gravities
G\"odel universe, one of the most interesting exact solutions predicted by
General Relativity, describes a homogeneous rotating universe containing naked
closed time-like curves (CTCs). It was shown that such CTCs are the consequence
of the null energy condition in General Relativity. In this paper, we show that
the G\"odel-type metrics with chronology protection can emerge in
Einstein-Horndeski gravity. We construct such exact solutions also in
Einstein-Horndeski-Maxwell and Einstein-Horndeski-Proca theories.Comment: Latex, 11 pages, references adde
Network analysis of the worldwide footballer transfer market
The transfer of football players is an important part in football games. Most
studies on the transfer of football players focus on the transfer system and
transfer fees but not on the transfer behavior itself. Based on the 470,792
transfer records from 1990 to 2016 among 23,605 football clubs in 206 countries
and regions, we construct a directed footballer transfer network (FTN), where
the nodes are the football clubs and the links correspond to the footballer
transfers. A systemic analysis is conduced on the topological properties of the
FTN. We find that the in-degrees, out-degrees, in-strengths and out-strengths
of nodes follow bimodal distributions (a power law with exponential decay),
while the distribution of link weights has a power-law tail. We further figure
out the correlations between node degrees, node strengths and link weights. We
also investigate the general characteristics of different measures of network
centrality. Our network analysis of the global footballer transfer market sheds
new lights into the investigation of the characteristics of transfer
activities.Comment: 7 pages, 6 figure
Data Unfolding with Wiener-SVD Method
Data unfolding is a common analysis technique used in HEP data analysis.
Inspired by the deconvolution technique in the digital signal processing, a new
unfolding technique based on the SVD technique and the well-known Wiener filter
is introduced. The Wiener-SVD unfolding approach achieves the unfolding by
maximizing the signal to noise ratios in the effective frequency domain given
expectations of signal and noise and is free from regularization parameter.
Through a couple examples, the pros and cons of the Wiener-SVD approach as well
as the nature of the unfolded results are discussed.Comment: 26 pages, 12 figures, match the accepted version by JINS
Godel Universe from String Theory
G\"odel universe is a direct product of a line and a three-dimensional
spacetime we call G. In this paper, we show that the G\"odel metrics
can arise as exact solutions in Einstein-Maxwell-Axion, Einstein-Proca-Axion,
or Freedman-Schwarz gauged supergravity theories. The last allows us to embed
G\"odel universe in string theory. The ten-dimensional spacetime is a direct
product of a line and the nine-dimensional one of an bundle
over G, and it can be interpreted as some decoupling limit of the
rotating D1/D5/D5 intersection. For some appropriate parameter choice, the
nine-dimensional metric becomes an AdS bundle over squashed
3-sphere. We also study the properties of the G\"odel black holes that are
constructed from the double Wick rotations of the G\"odel metrics.Comment: latex, 20 pages, discussion on null-energy condition included, typos
corrected and references adde
Branching Ratios, Forward-backward Asymmetry and Angular Distributions of Decays
Using the form factors evaluated in the perturbative QCD approach,
we study semileptonic and decays,
where and are mixtures of and which
are and states, respectively. Using the technique of helicity
amplitudes, we express the decay amplitudes in terms of several independent and
Lorentz invariant pieces. We study the dilepton invariant mass distributions,
branching ratios, polarizations and forward-backward asymmetries of decays. The ambiguity in the sign of the mixing angle will induce
much large differences to branching ratios of semileptonic B decays: branching
ratios without resonant contributions either have the order of or
. But the polarizations and the forward-backward asymmetries are not
sensitive to the mixing angles. We find that the resonant contributions will
dramatically change the dilepton invariant mass distributions in the resonant
region. We also provide the angular distributions of decays.Comment: 14 pages, 6 figures, version appears in PR
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