1,751 research outputs found
Deformations of plane algebraic curves and integrable systems of hydrodynamic type
We describe our recent work on deformations of hyperelliptic curves by means
of integrable hierarchy of hydrodynamic type (nlin.SI/0205012). We also discuss
a further extension to the case of non-hyperelliptic curves.Comment: 7 pages, Submitted for the WSPC Proceedings of Gallipoli workshop
July 26 - Aug. 6, 200
"Does e-Commerce Always Increase Social Welfare in the Long Run?"
We examine the effect of electronic commerce ("e-commerce") on social welfare, in the framework of conventional spatial competition models. We consider the case where both conventional and electronic retailers coexist in equilibrium. We show that e-commerce does not necessarily increase social welfare in the long run. In particular, when electronic retailers have clear cost advantage over conventional retailers, then the advent of e-commerce is shown to reduce social welfare.
The Strength and Nature of Bequest Motives in the United States
In this paper, we analyze the strength and nature of bequest motives in the United States using data from the 2000 Health and Retirement Study (HRS). The results of our analysis suggest that bequest motives are very strong in the United States and that they are altruistically motivated. This suggests that the altruism (or dynasty) model applies in the United States and that the selfish life cycle model does not apply. Moreover, our results also suggest that older, wealthier, married, more highly educated, Caucasian, healthy, and non-religious individuals are more likely to leave a bequest than other individuals.Bequests, Bequest Motives, Altruism, Life Cycle Model, Household Behavior
Non-Abelian statistics of vortices with non-Abelian Dirac fermions
We extend our previous analysis on the exchange statistics of vortices having
a single Dirac fermion trapped in each core, to the case where vortices trap
two Dirac fermions with U(2) symmetry. Such a system of vortices with
non-Abelian Dirac fermions appears in color superconductors at extremely high
densities, and in supersymmetric QCD. We show that the exchange of two vortices
having doublet Dirac fermions in each core is expressed by non-Abelian
representations of a braid group, which is explicitly verified in the matrix
representation of the exchange operators when the number of vortices is up to
four. We find that the result contains the matrices previously obtained for the
vortices with a single Dirac fermion in each core as a special case. The whole
braid group does not immediately imply non-Abelian statistics of identical
particles because it also contains exchanges between vortices with different
numbers of Dirac fermions. However, we find that it does contain, as its
subgroup, a genuine non-Abelian statistics for the exchange of the identical
particles, that is, vortices with the same number of Dirac fermions. This
result is surprising compared with conventional understanding because all Dirac
fermions are defined locally at each vortex, unlike the case of Majorana
fermions for which Dirac fermions are defined non-locally by Majorana fermions
located at two spatially separated vortices.Comment: 32 pages, no figures, v3: published versio
N-soliton solutions to the DKP equation and Weyl group actions
We study soliton solutions to the DKP equation which is defined by the Hirota
bilinear form, {\begin{array}{llll} (-4D_xD_t+D_x^4+3D_y^2)
\tau_n\cdot\tau_n=24\tau_{n-1}\tau_{n+1}, (2D_t+D_x^3\mp 3D_xD_y) \tau_{n\pm
1}\cdot\tau_n=0 \end{array} \quad n=1,2,.... where . The
-functions are given by the pfaffians of certain skew-symmetric
matrix. We identify one-soliton solution as an element of the Weyl group of
D-type, and discuss a general structure of the interaction patterns among the
solitons. Soliton solutions are characterized by skew-symmetric
constant matrix which we call the -matrices. We then find that one can have
-soliton solutions with being any number from to for some of
the -matrices having only nonzero entries in the upper
triangular part (the number of solitons obtained from those -matrices was
previously expected to be just ).Comment: 22 pages, 12 figure
Recommended from our members
Generation of bulk vorticity and current density in current-vortex sheet models
Rigid Limit in N=2 Supergravity and Weak-Gravity Conjecture
We analyze the coupled N=2 supergravity and Yang-Mills system using
holomorphy, near the rigid limit where the former decouples from the latter. We
find that there appears generically a new mass scale around g M_{pl} where g is
the gauge coupling constant and M_{pl} is the Planck scale. This is in accord
with the weak-gravity conjecture proposed recently. We also study the scale
dependence of the gauge theory prepotential from its embedding into
supergravity.Comment: 17 pages, minor correction
Soft-Fermion-Pole Mechanism to Single Spin Asymmetry in Hadronic Pion Production
Single spin asymmetry (SSA) is a twist-3 observable in the collinear
factorization approach. We present a twist-3 single-spin-dependent cross
section formula for the pion production in pp-collision, p^\uparrow p\to\pi X,
relevant to RHIC experiment. In particular, we calculate the soft-fermion-pole
(SFP) contribution to the cross section from the quark-gluon correlation
functions. We show that its effect can be as large as the soft-gluon-pole (SGP)
contribution owing to the large SFP partonic hard cross section, even though
the derivative of the SFP function does not participate in the cross section.Comment: 4 pages, 1 figure; to appear in the proceedings of the 18th
International Symposium on Spin Physics (SPIN2008), October 6 - 11, 2008,
Charlottesville, Virginia, US
Twist-3 Single-Spin Asymmetry for SIDIS and its Azimuthal Structure
We derive the complete twist-3 single-spin-dependent cross section for
semi-inclusive DIS, , associated with the complete set
of the twist-3 quark-gluon correlation functions in the transversely polarized
nucleon, extending our previous study. The cross section consists of five
independent structure functions with different azimuthal dependences,
consistently with the transverse-momentum-dependent (TMD) factorization
approach in the low region. Correspondence with the inclusive DIS limit
and comparison with the TMD approach are briefly discussed.Comment: 4 pages, 2 figures; to appear in the proceedings of the 18th
International Symposium on Spin Physics (SPIN2008), October 6 - 11, 2008,
Charlottesville, Virginia, US
Quantum phase transition of dynamical resistance in a mesoscopic capacitor
We study theoretically dynamic response of a mesoscopic capacitor, which
consists of a quantum dot connected to an electron reservoir via a point
contact and capacitively coupled to a gate voltage. A quantum Hall edge state
with a filling factor nu is realized in a strong magnetic field applied
perpendicular to the two-dimensional electron gas. We discuss a noise-driven
quantum phase transition of the transport property of the edge state by taking
into account an ohmic bath connected to the gate voltage. Without the noise,
the charge relaxation for nu>1/2 is universally quantized at R_q=h/(2e^2),
while for nu<1/2, the system undergoes the Kosterlitz-Thouless transtion, which
drastically changes the nature of the dynamical resistance. The phase
transition is facilitated by the noisy gate voltage, and we see that it can
occur even for an integer quantum Hall edge at nu=1. When the dissipation by
the noise is sufficiently small, the quantized value of R_q is shifted by the
bath impedance.Comment: 5 pages, 2 figures, proceeding of the 19th International Conference
on the Application of High Magnetic Fields in Semiconductor Physics and
Nanotechnology (HMF-19
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