83,741 research outputs found
A rotating string model versus baryon spectra
We continue our program of describing hadrons as rotating strings with
massive endpoints. In this paper we propose models of baryons and confront them
with the baryon Regge trajectories. We show that these are best fitted by a
model of a single string with a quark at one endpoint and a diquark at the
other. This model is preferred over the Y-shaped string model with a quark at
each endpoint. We show how the model follows from a stringy model of the
holographic baryon which includes a baryonic vertex connected with N_c strings
to flavor probe branes. From fitting to baryonic data we find that there is no
clear evidence for a non-zero baryonic vertex mass, but if there is such a mass
it should be located at one of the string endpoints. The available baryon
trajectories in the angular momentum plane (J,M^2), involving light, strange,
and charmed baryons, are rather well fitted when adding masses to the string
endpoints, with a single universal slope of 0.95 GeV^-2. Most of the results
for the quark masses are then found to be consistent with the results extracted
from the meson spectra in a preceding paper, where the value of the slope
emerging from the meson fits was found to be 0.90 GeV^-2. In the plane of
quantum radial excitations, (n,M^2), we also find a good agreement between the
meson and baryon slopes. The flavor structure of the diquark is examined, where
our interest lies in particular on baryons composed of more than one quark
heavier than the u and d quarks. For these baryons we present a method of
checking the holographic interpretation of our results.Comment: v2: typos corrected, references added, 41 pages; v3: added some
sentences to clarify the relation between our model and the holograhic
string, 42 page
Probabilistic Mass-Radius Relationship for Sub-Neptune-Sized Planets
The Kepler Mission has discovered thousands of planets with radii $<4\
R_\oplusM/M_\oplus=2.7(R/R_\oplus)^{1.3}1.9\ M_\oplusR_{pl}<4\ R_\oplus$). More broadly, this work provides a
framework for further analyses of the M-R relation and its probable
dependencies on period and stellar properties.Comment: 14 pages, 5 figures, 2 tables. Accepted to the Astrophysical Journal
on April 28, 2016. Select posterior samples and code to use them to compute
the posterior predictive mass distribution are available at
https://github.com/dawolfgang/MRrelatio
OPUCEM: A Library with Error Checking Mechanism for Computing Oblique Parameters
After a brief review of the electroweak radiative corrections to gauge-boson
self-energies, otherwise known as the direct and oblique corrections, a tool
for calculation of the oblique parameters is presented. This tool, named
OPUCEM, brings together formulas from multiple physics models and provides an
error-checking machinery to improve reliability of numerical results. It also
sets a novel example for an "open-formula" concept, which is an attempt to
improve the reliability and reproducibility of computations in scientific
publications by encouraging the authors to open-source their numerical
calculation programs. Finally, we demonstrate the use of OPUCEM in two detailed
case studies related to the fourth Standard Model family. The first is a
generic fourth family study to find relations between the parameters compatible
with the EW precision data and the second is the particular study of the Flavor
Democracy predictions for both Dirac and Majorana-type neutrinos.Comment: 10 pages, 19 figures, section 3 and 4 reviewed, results unchanged,
typo correction
Automatic one-loop calculation of MSSM processes with GRACE
We have developed the system for the automatic computation of cross-sections,
{\tt GRACE/SUSY}, including the one-loop calculations for processes of the
minimal supersymmetric extension of the the standard model. For an application,
we investigate the process .Comment: 4 pages, 1 figure, Talk presented by Jimbo, M. at ACAT-0
Is it Physically Sound to Add a Topologically Massive Term to Three-Dimensional Massive Electromagnetic or Gravitational Models ?
The addition of a topologically massive term to an admittedly non-unitary
three-dimensional massive model, be it an electromagnetic system or a
gravitational one, does not cure its non-unitarity. What about the enlargement
of avowedly unitary massive models by way of a topologically massive term? The
electromagnetic models remain unitary after the topological augmentation but,
surprisingly enough, the gravitational ones have their unitarity spoiled. Here
we analyze these issues and present the explanation why unitary massive
gravitational models, unlike unitary massive electromagnetic ones, cannot
coexist from the viewpoint of unitarity with topologically massive terms. We
also discuss the novel features of the three-term effective field models that
are gauge-invariant
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