49,098 research outputs found
Possible textures of the fermion mass matrices
Texture specific fermion mass matrices have played an important role in
understanding several features of fermion masses and mixings. In the present
work, we have given an overview of all possible cases of Fritzsch-like as well
as non Fritzsch-like texture 6 and 5 zero fermion mass matrices. Further, for
the case of texture 4 zero Fritzsch-like quark mass matrices, the issue of the
hierarchy of the elements of the mass matrices and the role of their phases
have been discussed. Furthermore, the case of texture 4 zero Fritzsch-like
lepton mass matrices has also been discussed with an emphasis on the hierarchy
of neutrino masses for both Majorana and Dirac neutrinos.Comment: 21 pages, 3 figure
Monotonicity results and bounds for the inverse hyperbolic sine
In this note, we present monotonicity results of a function involving to the
inverse hyperbolic sine. From these, we derive some inequalities for bounding
the inverse hyperbolic sine.Comment: 3 page
Metastable helium molecules as tracers in superfluid liquid He
Metastable helium molecules generated in a discharge near a sharp tungsten
tip operated in either pulsed mode or continuous field-emission mode in
superfluid liquid He are imaged using a laser-induced-fluorescence
technique. By pulsing the tip, a small cloud of He molecules is
produced. At 2.0 K, the molecules in the liquid follow the motion of the normal
fluid. We can determine the normal-fluid velocity in a heat-induced counterflow
by tracing the position of a single molecule cloud. As we run the tip in
continuous field-emission mode, a normal-fluid jet from the tip is generated
and molecules are entrained in the jet. A focused 910 nm pump laser pulse is
used to drive a small group of molecules to the vibrational state.
Subsequent imaging of the tagged molecules with an expanded 925 nm probe
laser pulse allows us to measure the velocity of the normal fluid. The
techniques we developed demonstrate for the first time the ability to trace the
normal-fluid component in superfluid helium using angstrom-sized particles.Comment: 4 pages, 7 figures. Submitted to Phys. Rev. Let
The Influences of Outflow on the Dynamics of Inflow
Both numerical simulations and observations indicate that in an
advection-dominated accretion flow most of the accretion material supplied at
the outer boundary will not reach the inner boundary. Rather, they are lost via
outflow. Previously, the influence of outflow on the dynamics of inflow is
taken into account only by adopting a radius-dependent mass accretion rate
with . In this paper, based on a 1.5
dimensional description to the accretion flow, we investigate this problem in
more detail by considering the interchange of mass, radial and azimuthal
momentum, and the energy between the outflow and inflow. The physical
quantities of the outflow is parameterized based on our current understandings
to the properties of outflow mainly from numerical simulations of accretion
flows. Our results indicate that under reasonable assumptions to the properties
of outflow, the main influence of outflow has been properly included by
adopting .Comment: 16 pages, 5 figures. accepted for publication in Ap
Real space first-principles derived semiempirical pseudopotentials applied to tunneling magnetoresistance
In this letter we present a real space density functional theory (DFT)
localized basis set semi-empirical pseudopotential (SEP) approach. The method
is applied to iron and magnesium oxide, where bulk SEP and local spin density
approximation (LSDA) band structure calculations are shown to agree within
approximately 0.1 eV. Subsequently we investigate the qualitative
transferability of bulk derived SEPs to Fe/MgO/Fe tunnel junctions. We find
that the SEP method is particularly well suited to address the tight binding
transferability problem because the transferability error at the interface can
be characterized not only in orbital space (via the interface local density of
states) but also in real space (via the system potential). To achieve a
quantitative parameterization, we introduce the notion of ghost semi-empirical
pseudopotentials extracted from the first-principles calculated Fe/MgO bonding
interface. Such interface corrections are shown to be particularly necessary
for barrier widths in the range of 1 nm, where interface states on opposite
sides of the barrier couple effectively and play a important role in the
transmission characteristics. In general the results underscore the need for
separate tight binding interface and bulk parameter sets when modeling
conduction through thin heterojunctions on the nanoscale.Comment: Submitted to Journal of Applied Physic
Strain induced pressure effect in pulsed laser deposited thin films of the strongly correlated oxide V2O3
V2O3 thin films about 10 nm thick were grown on Al2O3 (0001) by pulsed laser
deposition. The XRD analysis is in agreement with R-3c space group. Some of
them exhibit the metal / insulator transition characteristic of V2O3 bulk
material and others samples exhibit a metallic behavior. For the latter, the
XPS analysis indicates an oxidation state of +III for vanadium. There is no
metal / insulator transition around 150 K in this sample and a strongly
correlated Fermi liquid rho = AT2 behavior of the resistivity at low
temperature is observed, with a value of A of 1.2 10-4 ohm cm, 3 times larger
than the bulk value at 25 kbar
On the two-photon decay width of the sigma meson
We shortly report on the two-photon decay width of the light -meson
interpreted as a quarkonium state. Results are given in dependence on the
-mass and the constituent mass of the light quark. The triangle
quark-loop diagram, responsible for the two-photon transition, is carefully
evaluated: a term in the transition amplitude, often omitted in literature,
results in destructive interference with the leading term. As a result we show
that the two-photon decay width of the in the quarkonium picture is
less than 1 keV for the physical range of parameters.Comment: 6 pages, 4 figure
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