2,082 research outputs found
Model Independent Analysis of the Forward-Backward Asymmetry for the Decay
The sensitivity of the zero position of the forward backward asymmetry
for the exclusive
decay is examined by using most general non-standard 4-fermion interactions.
Our analysis shows that the zero position of the forward backward asymmetry is
very sensitive to the sign and size of the Wilson coefficients corresponding to
the new vector type interactions, which are the counter partners of the usual
Standard Model operators but have opposite chirality. In addition to these, the
other significant effect comes from the interference of Scalar-Pseudoscalar and
Tensor type operators. These results will not only enhance our theoretical
understanding about the axial vector mesons but will also serve as a good tool
to look for physics beyond the SM.Comment: 14 pages, 8 figures, Published version that appears in EPJ
Reflection and Ducting of Gravity Waves Inside the Sun
Internal gravity waves excited by overshoot at the bottom of the convection
zone can be influenced by rotation and by the strong toroidal magnetic field
that is likely to be present in the solar tachocline. Using a simple Cartesian
model, we show how waves with a vertical component of propagation can be
reflected when traveling through a layer containing a horizontal magnetic field
with a strength that varies with depth. This interaction can prevent a portion
of the downward-traveling wave energy flux from reaching the deep solar
interior. If a highly reflecting magnetized layer is located some distance
below the convection zone base, a duct or wave guide can be set up, wherein
vertical propagation is restricted by successive reflections at the upper and
lower boundaries. The presence of both upward- and downward-traveling
disturbances inside the duct leads to the existence of a set of horizontally
propagating modes that have significantly enhanced amplitudes. We point out
that the helical structure of these waves makes them capable of generating an
alpha-effect, and briefly consider the possibility that propagation in a shear
of sufficient strength could lead to instability, the result of wave growth due
to over-reflection.Comment: 23 pages, 5 figures. Accepted for publication in Solar Physic
Amplitude to phase conversion of InGaAs pin photo-diodes for femtosecond lasers microwave signal generation
When a photo-diode is illuminated by a pulse train from a femtosecond laser,
it generates microwaves components at the harmonics of the repetition rate
within its bandwidth. The phase of these components (relative to the optical
pulse train) is known to be dependent on the optical energy per pulse. We
present an experimental study of this dependence in InGaAs pin photo-diodes
illuminated with ultra-short pulses generated by an Erbium-doped fiber based
femtosecond laser. The energy to phase dependence is measured over a large
range of impinging pulse energies near and above saturation for two typical
detectors, commonly used in optical frequency metrology with femtosecond laser
based optical frequency combs. When scanning the optical pulse energy, the
coefficient which relates phase variations to energy variations is found to
alternate between positive and negative values, with many (for high harmonics
of the repetition rate) vanishing points. By operating the system near one of
these vanishing points, the typical amplitude noise level of commercial-core
fiber-based femtosecond lasers is sufficiently low to generate state-of-the-art
ultra-low phase noise microwave signals, virtually immune to amplitude to phase
conversion related noise.Comment: 7 pages, 6 figures, submitted to Applied Physics
Charge-density wave formation in Sr_{14}Cu_{24}O_{41}
The electrodynamic response of the spin-ladder compound
SrCaCuO () has been studied from
radiofrequencies up to the infrared. At temperatures below 250 K a pronounced
absorption peak appears around 12 cm in SrCuO for
the radiation polarized along the chains/ladders ().
In addition a strongly temperature dependent dielectric relaxation is observed
in the kHz - MHz range. We explain this behavior by a charge density wave which
develops in the ladders sub-system and produces a mode pinned at 12 cm.
With increasing Ca doping the mode shifts up in frequency and eventually
disappears for because the dimensionality of the system crosses over from
one to two dimensions, giving way to the superconducting ground state under
pressure.Comment: One name added to author list 4 pages, 2 figures, email:
[email protected]
Scanning Fourier Spectroscopy: A microwave analog study to image transmission paths in quantum dots
We use a microwave cavity to investigate the influence of a movable absorbing
center on the wave function of an open quantum dot. Our study shows that the
absorber acts as a position-selective probe, which may be used to suppress
those wave function states that exhibit an enhancement of their probability
density near the region where the impurity is located. For an experimental
probe of this wave function selection, we develop a technique that we refer to
as scanning Fourier spectroscopy, which allows us to identify, and map out, the
structure of the classical trajectories that are important for transmission
through the cavity.Comment: 4 pages, 5 figure
Light-cone QCD Sum Rules for the Baryon Electromagnetic Form Factors and its magnetic moment
We present the light-cone QCD sum rules up to twist 6 for the electromagnetic
form factors of the baryon. To estimate the magnetic moment of the
baryon, the magnetic form factor is fitted by the dipole formula. The numerical
value of our estimation is , which is in
accordance with the experimental data and the existing theoretical results. We
find that it is twist 4 but not the leading twist distribution amplitudes that
dominate the results.Comment: 13 page, 7 figures, accepted for publication in Euro. Phys. J.
Optical and transport properties in doped two-leg ladder antiferromagnet
Within the t-J model, the optical and transport properties of the doped
two-leg ladder antiferromagnet are studied based on the fermion-spin theory. It
is shown that the optical and transport properties of the doped two-leg ladder
antiferromagnet are mainly governed by the holon scattering. The low energy
peak in the optical conductivity is located at a finite energy, while the
resistivity exhibits a crossover from the high temperature metallic-like
behavior to the low temperature insulating-like behavior, which are consistent
with the experiments.Comment: 13 pages, 5 figures, accepted for publication in Phys. Rev. B65
(2002) (April 15 issue
Model independent analysis of 'Lambda' baryon polarizations in (Lambda_b -> Lambda l^+ l^-) decay
We present the model independent analysis of baryon polarizations
in the (Lambda_b -> Lambda l^+ l^-) decay. The sensitivity of the averaged
'Lambda' polarizations to the new Wilson coefficients is studied. It is
observed that there exist certain regions of the new Wilson coefficients where
the branching ratio coincides with the standard model prediction, while the
'Lambda' baryon polarizations deviate from the standard model results
remarkably.Comment: 19 pages, 9 figures, LaTeX formatte
Molecular correlates of response to capmatinib in advanced non-small-cell lung cancer: clinical and biomarker results from a phase I trial
Background: Dysregulation of receptor tyrosine kinase MET by various mechanisms occurs in 3%–4% of non-small-cell lung cancer (NSCLC) and is associated with unfavorable prognosis. While MET is a validated drug target in lung cancer, the best biomarker strategy for the enrichment of a susceptible patient population still remains to be defined. Towards this end we analyze here primary data from a phase I dose expansion study of the MET inhibitor capmatinib in patients with advanced MET-dysregulated NSCLC. Patients and methods: Eligible patients [≥18 years; Eastern Cooperative Oncology Group (ECOG) performance status ≤2] with MET-dysregulated advanced NSCLC, defined as either (i) MET status by immunohistochemistry (MET IHC) 2+ or 3+ or H-score ≥150, or MET/centromere ratio ≥2.0 or gene copy number (GCN) ≥5, or (ii) epidermal growth factor receptor wild-type (EGFRwt) and centrally assessed MET IHC 3+, received capmatinib at the recommended dose of 400 mg (tablets) or 600 mg (capsules) b.i.d. The primary objective was to determine safety and tolerability; the key secondary objective was to explore antitumor activity. The exploratory end point was the correlation of clinical activity with different biomarker formats. Results: Of 55 patients with advanced MET-dysregulated NSCLC, 40/55 (73%) had received two or more prior systemic therapies. All patients discontinued treatment, primarily due to disease progression (69.1%). The median treatment dur
Phase diagrams of spin ladders with ferromagnetic legs
The low-temperature properties of the spin S=1/2 ladder with anisotropic
ferromagnetic legs are studied using the continuum limit bosonization approach.
The weak-coupling ground state phase diagram of the model is obtained for a
wide range of coupling constants and several unconventional gapless
''spin-liquid'' phases are shown to exist for ferromagnetic coupling. The
behavior of the ladder system in the vicinity of the ferromagnetic instability
point is discussed in detail.Comment: 11 pages, 4 figure
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