67,845 research outputs found
N-fold Parasupersymmetry
We find a new type of non-linear supersymmetries, called N-fold
parasupersymmetry, which is a generalization of both N-fold supersymmetry and
parasupersymmetry. We provide a general formulation of this new symmetry and
then construct a second-order N-fold parasupersymmetric quantum system where
all the components of N-fold parasupercharges are given by type A N-fold
supercharges. We show that this system exactly reduces to the
Rubakov-Spiridonov model when N=1 and admits a generalized type C 2N-fold
superalgebra. We conjecture the existence of other `N-fold generalizations'
such as N-fold fractional supersymmetry, N-fold orthosupersymmetry, and so on.Comment: 10 pages, no figures; Intro. expande
Hands-on Physical Science Course at Radford University
Most students in our introductory physical science course are elementary education majors. We are faced with several obstacles in teaching basic science to these students. For example, they lack interest in science, logical thinking, and necessary data gathering and analysis skills, among others. Many of those obstacles could be traced back to the science courses they had taken in the past. Those courses put more emphasis on memorizing scientific facts than understanding natural phenomena or experiencing scientific methods. As a result, the students tend to have a negative attitude toward science in general. In order to reverse this attitude, We have been developing a hands-on, experience based physical science course. In each class students are asked to perform several experiments which require observation, data gathering, and analysis. The instructor provides necessary scientific background and explanation on the experiments as they go. One of the experiments the students enjoyed a lot is the measurement of average speeds of cars. They actually go out on the street and take data. Through this course students can experience how science works and learn that science could be more exciting than just memorizing
Transport through a single Anderson impurity coupled to one normal and two superconducting leads
We study the interplay between the Kondo and Andreev-Josephson effects in a
quantum dot coupled to one normal and two superconducting (SC) leads. In the
large gap limit, the low-energy states of this system can be described exactly
by a local Fermi liquid for the interacting Bogoliubov particles. The phase
shift and the renormalized parameters for the Bogoliubov particles vary
depending on the Josephson phase between the two SC leads. We explore the
precise features of a crossover that occurs between the Kondo singlet and local
Cooper-pairing states as the Josephson phase varies, using the numerical
renormalization group approach.Comment: 4 pages, 4 figures, contribution to SCES 201
Buckling of swelling gels
The patterns arising from the differential swelling of gels are investigated
experimentally and theoretically as a model for the differential growth of
living tissues. Two geometries are considered: a thin strip of soft gel clamped
to a stiff gel, and a thin corona of soft gel clamped to a disk of stiff gel.
When the structure is immersed in water, the soft gel swells and bends out of
plane leading to a wavy periodic pattern which wavelength is measured. The
linear stability of the flat state is studied in the framework of linear
elasticity using the equations for thin plates. The flat state is shown to
become unstable to oscillations above a critical swelling rate and the computed
wavelengths are in quantitative agreement with the experiment
DECIGO/BBO as a probe to constrain alternative theories of gravity
We calculate how strongly one can constrain the alternative theories of
gravity with deci-Hz gravitational wave interferometers such as DECIGO and BBO.
Here we discuss Brans-Dicke theory and massive graviton theories as typical
examples. We consider the inspiral of compact binaries composed of a neutron
star (NS) and an intermediate mass black hole (IMBH) for Brans-Dicke (BD)
theory and those composed of a super massive black hole (SMBH) and a black hole
(SMBH) for massive graviton theories. Using the restricted 2PN waveforms
including spin effects and taking the spin precession into account, we perform
the Monte Carlo simulations of binaries to estimate the determination
accuracy of binary parameters including the Brans-Dicke parameter
and the graviton Compton length . Assuming a
NS/BH binary of SNR=, the constraint on
is obtained as ,
which is 300 times stronger than the estimated constraint from LISA
observation. Furthermore, we find that, due to the expected large merger rate
of NS/BH binaries of yr, a statistical analysis yields
, which is 4 orders of magnitude stronger
than the current strongest bound obtained from the solar system experiment. For
massive graviton theories, assuming a BH/BH binary at
3Gpc, one can put a constraint cm, on average.
This is three orders of magnitude stronger than the one obtained from the solar
system experiment. From these results, it is understood that DECIGO/BBO is a
very powerful tool for constraining alternative theories of gravity, too.Comment: 4 pages, 3 figures; Accepted to Prog. Theor. Phys. Letters; Many
interpretations and some references have been added; Some Coding errors being
corrected and the final constraints came out stronge
- …