22,848 research outputs found
Proton Decay and Fermion Masses in Supersymmetric SO(10) Model with Unified Higgs Sector
We make a detailed analysis on the proton decay in a supersymmetric SO(10)
model proposed by K.Babu, I.Gogoladze, P.Nath, and R. Syed. We introduce quark
mixing, and find that this model can generate fermion mass without breaking the
experimental bound on proton decay. We also predict large CKM unitarity
violations.Comment: 7 page
Cooperative Transmission Protocols with High Spectral Efficiency and High Diversity Order Using Multiuser Detection and Network Coding
Cooperative transmission is an emerging communication technique that takes
advantages of the broadcast nature of wireless channels. However, due to low
spectral efficiency and the requirement of orthogonal channels, its potential
for use in future wireless networks is limited. In this paper, by making use of
multiuser detection (MUD) and network coding, cooperative transmission
protocols with high spectral efficiency, diversity order, and coding gain are
developed. Compared with the traditional cooperative transmission protocols
with single-user detection, in which the diversity gain is only for one source
user, the proposed MUD cooperative transmission protocols have the merits that
the improvement of one user's link can also benefit the other users. In
addition, using MUD at the relay provides an environment in which network
coding can be employed. The coding gain and high diversity order can be
obtained by fully utilizing the link between the relay and the destination.
From the analysis and simulation results, it is seen that the proposed
protocols achieve higher diversity gain, better asymptotic efficiency, and
lower bit error rate, compared to traditional MUD and to existing cooperative
transmission protocols.Comment: to appear, in the proceedings of IEEE International Conference on
Communications, Glasgow, Scotland, 24-28 June 200
Universality of the edge tunneling exponent of fractional quantum Hall liquids
Recent calculations of the edge tunneling exponents in quantum Hall states
appear to contradict their topological nature. We revisit this issue and find
no fundamental discrepancies. In a microscopic model of fractional quantum Hall
liquids with electron-electron interaction and confinement, we calculate the
edge Green's function via exact diagonalization. Our results for
and 2/3 suggest that in the presence of Coulomb interaction, the sharpness of
the edge and the strength of the edge confining potential, which can lead to
edge reconstruction, are the parameters that are relevant to the universality
of the electron tunneling I-V exponent.Comment: 5 pages, 3 figure
Edge Excitations and Non-Abelian Statistics in the Moore-Read State: A Numerical Study in the Presence of Coulomb Interaction and Edge Confinement
We study the ground state and low-energy excitations of fractional quantum
Hall systems on a disk at filling fraction , with Coulomb
interaction and background confining potential. We find the Moore-Read ground
state is stable within a finite but narrow window in parameter space. The
corresponding low-energy excitations contain a fermionic branch and a bosonic
branch, with widely different velocities. A short-range repulsive potential can
stabilize a charge quasihole at the center, leading to a different edge
excitation spectrum due to the change of boundary conditions for Majorana
fermions, clearly indicating the non-Abelian nature of the quasihole.Comment: 4 pages, 3 figures. New version shortened for PRL. Corrected typo
Black hole evaporation based upon a q-deformation description
A toy model based upon the -deformation description for studying the
radiation spectrum of black hole is proposed. The starting point is to make an
attempt to consider the spacetime noncommutativity in the vicinity of black
hole horizon. We use a trick that all the spacetime noncommutative effects are
ascribed to the modification of the behavior of the radiation field of black
hole and a kind of q-deformed degrees of freedom are postulated to mimic the
radiation particles that live on the noncommutative spacetime, meanwhile the
background metric is preserved as usual. We calculate the radiation spectrum of
Schwarzschild black hole in this framework. The new distribution deviates from
the standard thermal spectrum evidently. The result indicates that some
correlation effect will be introduced to the system if the noncommutativity is
taken into account. In addition, an infrared cut-off of the spectrum is the
prediction of the model.Comment: 13 pages, 2 figure
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