3,034 research outputs found
On subgroups in division rings of type
Let be a division ring with center . We say that is a {\em
division ring of type } if for every two elements the division
subring is a finite dimensional vector space over . In this paper
we investigate multiplicative subgroups in such a ring.Comment: 10 pages, 0 figure
Seesaw Right Handed Neutrino as the Sterile Neutrino for LSND
We show that a double seesaw framework for neutrino masses with
exchange symmetry can lead to one of the righthanded seesaw partners of the
light neutrinos being massless. This can play the role of a light sterile
neutrino, giving a model that explains the LSND results. We get a very
economical scheme, which makes it possible to predict the full
neutrino mass matrix if CP is conserved. Once CP violation is included, effect
of the LSND mass range sterile neutrino is to eliminate the lower bound on
neutrinoless double beta decay rate which exists for the three neutrino case
with inverted mass hierarchy. The same strategy can also be used to generate a
natural model for LSND, which is also equally predictive for the CP
conserving case in the limit of exact symmetry.Comment: 13 pages and one figure; model extended to 3+2 cas
Experimental Realization of Br\"{u}schweiler's exponentially fast search algorithm in a homo-nuclear system
Compared with classical search algorithms, Grover quantum algorithm [ Phys.
Rev. Lett., 79, 325(1997)] achieves quadratic speedup and Bruschweiler hybrid
quantum algorithm [Phys. Rev. Lett., 85, 4815(2000)] achieves an exponential
speedup. In this paper, we report the experimental realization of the
Bruschweiler$ algorithm in a 3-qubit NMR ensemble system. The pulse sequences
are used for the algorithms and the measurement method used here is improved on
that used by Bruschweiler, namely, instead of quantitatively measuring the spin
projection of the ancilla bit, we utilize the shape of the ancilla bit
spectrum. By simply judging the downwardness or upwardness of the corresponding
peaks in an ancilla bit spectrum, the bit value of the marked state can be read
out, especially, the geometric nature of this read-out can make the results
more robust against errors.Comment: 10 pages and 3 figure
A Comprehensive View of a Strongly Lensed Planck-Associated Submillimeter Galaxy
We present high-resolution maps of stars, dust, and molecular gas in a strongly lensed submillimeter galaxy (SMG) at z = 3.259. HATLAS J114637.9–001132 is selected from the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS) as a strong lens candidate mainly based on its unusually high 500 μm flux density (~300 mJy). It is the only high-redshift Planck detection in the 130 deg^2 H-ATLAS Phase-I area. Keck Adaptive Optics images reveal a quadruply imaged galaxy in the K band while the Submillimeter Array and the Jansky Very Large Array show doubly imaged 880 μm and CO(1→0) sources, indicating differentiated distributions of the various components in the galaxy. In the source plane, the stars reside in three major kpc-scale clumps extended over ~1.6 kpc, the dust in a compact (~1 kpc) region ~3 kpc north of the stars, and the cold molecular gas in an extended (~7 kpc) disk ~5 kpc northeast of the stars. The emissions from the stars, dust, and gas are magnified by ~17, ~8, and ~7 times, respectively, by four lensing galaxies at z ~ 1. Intrinsically, the lensed galaxy is a warm (T_(dust) ~ 40-65 K), hyper-luminous (L_(IR) ~ 1.7 × 10^(13) L_☉; star formation rate (SFR) ~2000 M_☉ yr^(–1)), gas-rich (M_(gas)/M_(baryon) ~ 70%), young (M_(stellar)/SFR ~ 20 Myr), and short-lived (M_(gas)/SFR ~ 40 Myr) starburst. With physical properties similar to unlensed z > 2 SMGs, HATLAS J114637.9–001132 offers a detailed view of a typical SMG through a powerful cosmic microscope
Charmless Three-body Decays of B Mesons
Charmless 3-body decays of B mesons are studied in the framework of the
factorization approach. The nonresonant contributions arising from transitions are evaluated using heavy meson chiral perturbation theory
(HMChPT). The momentum dependence of nonresonant amplitudes is assumed to be in
the exponential form e^{-\alpha_{NR}} p_B\cdot(p_i+p_j)} so that the HMChPT
results are recovered in the soft meson limit . In addition, we
have identified another large source of the nonresonant signal in the matrix
elements of scalar densities, e.g. , which can be
constrained from the decay or . The
intermediate vector meson contributions to 3-body decays are identified through
the vector current, while the scalar meson resonances are mainly associated
with the scalar density. Their effects are described in terms of the
Breit-Wigner formalism. Our main results are: (i) All KKK modes are dominated
by the nonresonant background. The predicted branching ratios of
, and modes are consistent with the
data within errors. (ii) Although the penguin-dominated
decay is subject to a potentially significant tree pollution, its effective
is very similar to that of the mode. However, direct
CP asymmetry of the former, being of order -4%, is more prominent than the
latter. (iii) For decays, we found sizable nonresonant
contributions in and modes, in agreement
with the Belle measurements but larger than the BaBar result.Comment: 39 pages, 2 figures, version to appear in PR
Natural Realizations of Seesaw in Mini-Warped Minimal SO(10)
The minimal SUSY SO(10) GUT models with {\bf 10}, {\bf 126} and {\bf 210}
Higgs and only renormalizable couplings has been shown to provide a simple way
to understand the neutrino mixings as well as the ratio in terms of quark mixing parameter ,
provided neutrino masses are described by type II seesaw formula. However, in
this minimal picture, it is impossible to realize type II dominance with
renormalizable couplings in 4-dimensions. We show that this problem can be
cured by embedding this model into a warped 5-dimensional space time with
warping between the Planck and the GUT scale, where both type II as well as
mixed seesaw formulae can be realized in a natural manner without expanding the
Higgs sector. These models also avoid the possible problem of threshold effects
associated with large Higgs representations since the theory above the GUT
scale is now strongly coupled.Comment: 20 pages and one figur
Supersymmetry Breaking by Type II Seesaw Assisted Anomaly Mediation
Anomaly mediated supersymmetry breaking (AMSB), when implemented in MSSM is
known to suffer from the problem of negative slepton mass squared leading to
breakdown of electric charge conservation. We show however that when MSSM is
extended to explain small neutrino masses by including a pair of superheavy
Higgs triplet superfields (the type II seesaw mechanism), the slepton masses
can be deflected from the pure AMSB trajectory and become positive. In a simple
model we present in this paper, the seesaw scale is about . Gauge coupling unification can be maintained by embedding the triplet to
SU(5) {\bf 15}-multiplet. In this scenario, bino is the LSP and its mass is
nearly degenerate with NLSP slepton when the triplet mass is right around the
seesaw scale.Comment: 18 pages, 4 figures, added references, added footnote
Phase-Dependent Spontaneous Spin Polarization and Bifurcation Delay in Coupled Two-Component Bose-Einstein Condensates
The spontaneous spin polarization and bifurcation delay in two-component
Bose-Einstein condensates coupled with laser or/and radio-frequency pulses are
investigated. We find that the bifurcation and the spontaneous spin
polarization are determined by both physical parameters and relative phase
between two condensates. Through bifurcations, the system enters into the
spontaneous spin polarization regime from the Rabi regime. We also find that
bifurcation delay appears when the parameter is swept through a static
bifurcation point. This bifurcation delay is responsible for metastability
leading to hysteresis.Comment: Improved version for cond-mat/021157
Conjecture on the Avoidance of the Big Crunch
KKLT give a mechanism to generate de Sitter vacua in string theory. And
recently, the scenario, {\em landscape}, is suggested to explain the problem of
the cosmological constant. In this scenario, the cosmological constant is a de
Sitter vacuum. The vacuum is metastable and would decay into an anti-de Sitter
vacuum finally. Then the catastrophe of the big crunch appears. In this paper
by conjecturing the physics at the Planck scale, we modify the definition of
the Hawking temperature. Hinted by this modification, we modify the Friedmann
equation. we find that this avoid the singularity and gives a bouncing
cosmological model.Comment: 6 page
Properties of weighted complex networks
We study two kinds of weighted networks, weighted small-world (WSW) and
weighted scale-free (WSF). The weight of a link between nodes and
in the network is defined as the product of endpoint node degrees; that is
. In contrast to adding weights to links during
networks being constructed, we only consider weights depending on the ``
popularity\rq\rq of the nodes represented by their connectivity. It was found
that the both weighted networks have broad distributions on characterization
the link weight, vertex strength, and average shortest path length.
Furthermore, as a survey of the model, the epidemic spreading process in both
weighted networks was studied based on the standard \emph{susceptible-infected}
(SI) model. The spreading velocity reaches a peak very quickly after the
infection outbreaks and an exponential decay was found in the long time
propagation.Comment: 14 pages, 5 figure
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