119,575 research outputs found
Conformal Couplings in Induced Gravity
It is found that the induced gravity with conformal couplings requires the
conformal invariance in both classical and quantum levels for consistency. This
is also true for the induced gravity with an extended conformal coupling
interacting with torsion.Comment: 10 pages, Revtex3.0, to appear in General Relativity and Gravitatio
orbifold compactifications in with Gauss-Bonnet term
We present a general setup for junctions of semi-infinite 4-branes in
with the Gauss-Bonnet term. The 3-brane tension at the junction of 4-branes can
be nonzero. Using the brane junctions as the origin of the discrete
rotation symmetry, we identify 3-brane tensions at three fixed points of the
orbifold in terms of the 4-brane tensions. As a result, the three
3-brane tensions can be simultaneously positive, which enables us to explain
the mass hierarchy by taking one of two branes apart from the hidden brane as
the visible brane, and hence does not introduce a severe cosmological problem.Comment: Latex file of 20 pages including 2 figure
Controllability of a viscoelastic plate using one boundary control in displacement or bending
In this paper we consider a viscoelastic plate (linear viscoelasticity of the
Maxwell-Boltzmann type) and we compare its controllability properties with the
(known) controllability of a purely elastic plate (the control acts on the
boundary displacement or bending). By combining operator and moment methods, we
prove that the viscoelastic plate inherits the controllability properties of
the purely elastic plate
Deutsch-Jozsa algorithm as a test of quantum computation
A redundancy in the existing Deutsch-Jozsa quantum algorithm is removed and a
refined algorithm, which reduces the size of the register and simplifies the
function evaluation, is proposed. The refined version allows a simpler analysis
of the use of entanglement between the qubits in the algorithm and provides
criteria for deciding when the Deutsch-Jozsa algorithm constitutes a meaningful
test of quantum computation.Comment: 10 pages, 2 figures, RevTex, Approved for publication in Phys Rev
Quantum criticality in Kondo quantum dot coupled to helical edge states of interacting 2D topological insulators
We investigate theoretically the quantum phase transition (QPT) between the
one-channel Kondo (1CK) and two-channel Kondo (2CK) fixed points in a quantum
dot coupled to helical edge states of interacting 2D topological insulators
(2DTI) with Luttinger parameter . The model has been studied in Ref. 21,
and was mapped onto an anisotropic two-channel Kondo model via bosonization.
For K<1, the strong coupling 2CK fixed point was argued to be stable for
infinitesimally weak tunnelings between dot and the 2DTI based on a simple
scaling dimensional analysis[21]. We re-examine this model beyond the bare
scaling dimension analysis via a 1-loop renormalization group (RG) approach
combined with bosonization and re-fermionization techniques near weak-coupling
and strong-coupling (2CK) fixed points. We find for K -->1 that the 2CK fixed
point can be unstable towards the 1CK fixed point and the system may undergo a
quantum phase transition between 1CK and 2CK fixed points. The QPT in our model
comes as a result of the combined Kondo and the helical Luttinger physics in
2DTI, and it serves as the first example of the 1CK-2CK QPT that is accessible
by the controlled RG approach. We extract quantum critical and crossover
behaviors from various thermodynamical quantities near the transition. Our
results are robust against particle-hole asymmetry for 1/2<K<1.Comment: 17 pages, 9 figures, more details added, typos corrected, revised
Sec. IV, V, Appendix A and
Multivariate p-dic L-function
We construct multivariate p-adic L-function in the p-adic number fild by
using Washington method.Comment: 9 page
Spin relaxation of two-dimensional holes in strained asymmetric SiGe quantum wells
We analyze spin splitting of the two-dimensional hole spectrum in strained
asymmetric SiGe quantum wells (QWs). Based on the Luttinger Hamiltonian, we
obtain expressions for the spin-splitting parameters up to the third order in
the in-plane hole wavevector. The biaxial strain of SiGe QWs is found to be a
key parameter that controls spin splitting. Application to SiGe field-effect
transistor structures indicates that typical spin splitting at room temperature
varies from a few tenth of meV in the case of Si QW channels to several meV for
the Ge counterparts, and can be modified efficiently by gate-controlled
variation of the perpendicular confining electric field. The analysis also
shows that for sufficiently asymmetric QWs, spin relaxation is due mainly to
the spin-splitting related D'yakonov-Perel' mechanism. In strained Si QWs, our
estimation shows that the hole spin relaxation time can be on the order of a
hundred picoseconds at room temperature, suggesting that such structures are
suitable for p-type spin transistor applications as well
On graphs with a large chromatic number containing no small odd cycles
In this paper, we present the lower bounds for the number of vertices in a
graph with a large chromatic number containing no small odd cycles
Internet data packet transport: from global topology to local queueing dynamics
We study structural feature and evolution of the Internet at the autonomous
systems level. Extracting relevant parameters for the growth dynamics of the
Internet topology, we construct a toy model for the Internet evolution, which
includes the ingredients of multiplicative stochastic evolution of nodes and
edges and adaptive rewiring of edges. The model reproduces successfully
structural features of the Internet at a fundamental level. We also introduce a
quantity called the load as the capacity of node needed for handling the
communication traffic and study its time-dependent behavior at the hubs across
years. The load at hub increases with network size as .
Finally, we study data packet traffic in the microscopic scale. The average
delay time of data packets in a queueing system is calculated, in particular,
when the number of arrival channels is scale-free. We show that when the number
of arriving data packets follows a power law distribution, ,
the queue length distribution decays as and the average delay
time at the hub diverges as in the limit when , being the network degree
exponent.Comment: 5 pages, 4 figures, submitted to International Journal of Bifurcation
and Chao
Search for Free Fractional Electric Charge Elementary Particles
We have carried out a direct search in bulk matter for free fractional
electric charge elementary particles using the largest mass single sample ever
studied - about 17.4 mg of silicone oil. The search used an improved and highly
automated Millikan oil drop technique. No evidence for fractional charge
particles was found. The concentration of particles with fractional charge more
than 0.16e (e being the magnitude of the electron charge) from the nearest
integer charge is less than particles per nucleon with 95%
confidence.Comment: 10 pages,LaTeX, 4 PS figures, submitted to PR
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