756 research outputs found
Hierarchical Mass Matrices in a Minimal SO(10) Grand Unification I
We consider a minimal SO(10) unified model with horizontal Peccei-Quinn
symmetry. The hierarchical structure of quark-lepton mass matrices is naturally
implemented by the remnants of certain irrelevant terms. Georgi-Jarlskog
relations are also realized due to the horizontal symmetry.Comment: phyzzx and tables, 15 pages, KUNS 125
Gauge Invariant Effective Lagrangian for Kaluza-Klein Modes
We construct a manifestly gauge invariant Lagrangian in 3+1 dimensions for N
Kaluza-Klein modes of an SU(m) gauge theory in the bulk. For example, if the
bulk is 4+1, the effective theory is \Pi_{i=1}^{N+1} SU(m)_i with N chiral
(\bar{m},m) fields connecting the groups sequentially. This can be viewed as a
Wilson action for a transverse lattice in x^5, and is shown explicitly to match
the continuum 4+1 compactifed Lagrangian truncated in momentum space. Scale
dependence of the gauge couplings is described by the standard renormalization
group technique with threshold matching, leading to effective power law
running. We also discuss the unitarity constraints, and chiral fermions.Comment: 21 pages, 4 figure
High sensitivity and multifunctional micro-Hall sensors fabricated using InAlSb/InAsSb/InAlSb heterostructures
Further diversification of Hall sensor technology requires development of materials with high electron mobility and an ultrathin conducting layer very close to the material's surface. Here, we describe the magnetoresistive properties of micro-Hall devices fabricated using InAlSb/InAsSb/InAlSb heterostructures where electrical conduction was confined to a 30 nm-InAsSb two-dimensional electron gas layer. The 300 K electron mobility and sheet carrier concentration were 36 500 cm(2) V-1 s(-1) and 2.5 x 10(11) cm(-2), respectively. The maximum current-related sensitivity was 2 750 V A(-1) T-1, which was about an order of magnitude greater than AlGaAs/InGaAs pseudomorphic heterostructures devices. Photolithography was used to fabricate 1 mu m x 1 mu m Hall probes, which were installed into a scanning Hall probe microscope and used to image the surface of a hard disk
Characteristics of Vehicular Traffic Flow at a Roundabout
We construct a stochastic cellular automata model for the description of
vehicular traffic at a roundabout designed at the intersection of two
perpendicular streets. The vehicular traffic is controlled by a self-organized
scheme in which traffic lights are absent. This controlling method incorporates
a yield-at-entry strategy for the approaching vehicles to the circulating
traffic flow in the roundabout. Vehicular dynamics is simulated within the
framework of the probabilistic cellular automata and the delay experienced by
the traffic at each individual street is evaluated for specified time
intervals. We discuss the impact of the geometrical properties of the
roundabout on the total delay. We compare our results with traffic-light
signalisation schemes, and obtain the critical traffic volume over which the
intersection is optimally controlled through traffic light signalisation
schemes.Comment: 10 pages, 17 eps figures. arXiv admin note: text overlap with
arXiv:cond-mat/040107
Towards a variational principle for motivated vehicle motion
We deal with the problem of deriving the microscopic equations governing the
individual car motion based on the assumptions about the strategy of driver
behavior. We suppose the driver behavior to be a result of a certain compromise
between the will to move at a speed that is comfortable for him under the
surrounding external conditions, comprising the physical state of the road, the
weather conditions, etc., and the necessity to keep a safe headway distance
between the cars in front of him. Such a strategy implies that a driver can
compare the possible ways of his further motion and so choose the best one. To
describe the driver preferences we introduce the priority functional whose
extremals specify the driver choice. For simplicity we consider a single-lane
road. In this case solving the corresponding equations for the extremals we
find the relationship between the current acceleration, velocity and position
of the car. As a special case we get a certain generalization of the optimal
velocity model similar to the "intelligent driver model" proposed by Treiber
and Helbing.Comment: 6 pages, RevTeX
Gauge Symmetry Enhancement and Radiatively Induced Mass in the Large N Nonlinear Sigma Model
We consider a hybrid of nonlinear sigma models in which two complex
projective spaces are coupled with each other under a duality. We study the
large N effective action in 1+1 dimensions. We find that some of the
dynamically generated gauge bosons acquire radiatively induced masses which,
however, vanish along the self-dual points where the two couplings
characterizing each complex projective space coincide. These points correspond
to the target space of the Grassmann manifold along which the gauge symmetry is
enhanced, and the theory favors the non-Abelian ultraviolet fixed point.Comment: 11 pages, REVTEX, typos are corrected, version to appear in Phys.
Rev.
Orbital selectivity of the kink in the dispersion of Sr2RuO4
We present detailed energy dispersions near the Fermi level on the monolayer
perovskite ruthenate Sr2RuO4, determined by high-resolution angle-resolved
photoemission spectroscopy. An orbital selectivity of the kink in the
dispersion of Sr2RuO4 has been found: A kink for the Ru 4d_xy orbital is
clearly observed, but not for the Ru 4d_yz and 4d_zx ones. The result provides
insight into the origin of the kink.Comment: 5 pages, 4 figures. Accepted for publication in Phys. Rev.
Infrared alignment of SUSY flavor structures
The various experimental bounds on flavor-changing interactions severely
restrict the low-energy flavor structures of soft supersymmetry breaking
parameters. In this work, we show that with a particular assumption of Yukawa
couplings, the fermion mass and sfermion soft mass matrices are simultaneously
diagonalized by common mixing matrices and we then obtain an alignment solution
for the flavor problems. The required condition is generated by renormalization
group evolutions and achieved at low-energy scale independently of high-energy
structures of couplings. In this case, the diagonal entries of the soft scalar
mass matrices are determined by gaugino and Higgs soft masses. We also discuss
possible realizations of this scenario and the characteristic sparticle
spectrum in the models.Comment: 18 pages, 1 figur
Infra-red stability of Yukawa and soft-breaking fixed points
We investigate the infra-red stability of the fixed points in the evolution
of the Yukawa couplings, -parameters and soft scalar masses in a broad class
of supersymmetric theories. We show that the issue of stability is essentially
determined in all three cases by the eigenvalues of the same matrix. In a very
wide range of physically interesting theories it follows that, in the
asymptotically free case, the existence of stable infra-red fixed points for
the Yukawa couplings implies stable infra-red fixed points for the
-parameters and soft scalar masses.Comment: 12 pages, tex, Uses harvmac (big). Errors corrected in Eqs.
(33)-(35), and some references adde
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