19,406 research outputs found
Faddeev fixed-center approximation to the system and the signature of a state
We perform a calculation for the three body scattering
amplitude by using the fixed center approximation to the Faddeev equations,
taking the interaction between and , and , and
and from the chiral unitary approach. The resonant structures show up in
the modulus squared of the three body scattering amplitude and suggest that a
hadron state can be formed. Our results are in agreement with
others obtained in previous theoretical works, which claim a new
resonance around 1920 MeV with spin-parity . The existence of these
previous works allows us to test the accuracy of the fixed center approximation
in the present problem and sets the grounds for possible application in similar
problems, as an explorative tool to determine bound or quasibound three hadron
systems.Comment: Published versio
Plausible explanation of the puzzle
From a Faddeev calculation for the
system we show the plausible existence of three dynamically generated
baryon states below 2.3 GeV whereas only two
resonances, and
are cataloged in the Particle Data Book
Review. Our results give theoretical support to data analyses extracting two
distinctive resonances, and
from which the mass of
is estimated. We propose that these two
resonances should be cataloged instead of This
proposal gets further support from the possible assignment of the other baryon
states found in the approach in the with
sectors to known baryonic resonances. In
particular, is naturally interpreted as a bound state.Comment: 13 pages, 7 figure
Theory of magnetoelastic resonance in a mono-axial chiral helimagnet
We study magnetoelastic resonance phenomena in a mono-axial chiral helimagnet
belonging to hexagonal crystal class. By computing the spectrum of coupled
elastic wave and spin wave, it is demonstrated how hybridization occurs
depending on their chirality. Specific features of the magnetoelastic resonance
are discussed for the conical phase and the soliton lattice phase stabilized in
the mono-axial chiral helimagnet. The former phase exhibits appreciable
non-reciprocity of the spectrum, the latter is characterized by a
multi-resonance behavior. We propose that the non-reciprocal spin wave around
the forced-ferromagnetic state has potential capability to convert the linearly
polarized elastic wave to circularly polarized one with the chirality opposite
to the spin wave chirality.Comment: 12 pages, 5 figures, Accepted in Phys. Rev.
The Market Price of Credit Risk: An Empirical Analysis of Interest Rate Swap Spreads
This paper studies the market price of credit risk incorporated into one of the most important credit spreads in the financial markets: interest rate swap spreads. Our approach consists of jointly modeling the swap and Treasury term structures using a general five-factor affine credit framework and estimating the parameters by maximum likelihood. We solve for the implied special financing rate for Treasury bonds and find that the liquidity component of on-the-run bond prices can be significant. We also find that credit premia in swap spreads are positive on average. These premia, however, vary significantly over time and were actually negative for much of the 1990s.
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Attenuation of hedgehog/GLI signaling by NT1721 extends survival in pancreatic cancer.
BackgroundPancreatic cancer is one of the most lethal malignancies due to frequent late diagnosis, aggressive tumor growth and metastasis formation. Continuously raising incidence rates of pancreatic cancer and a lack of significant improvement in survival rates over the past 30 years highlight the need for new therapeutic agents. Thus, new therapeutic agents and strategies are urgently needed to improve the outcome for patients with pancreatic cancer. Here, we evaluated the anti-tumor activity of a new natural product-based epidithiodiketopiperazine, NT1721, against pancreatic cancer.MethodsWe characterized the anticancer efficacy of NT1721 in multiple pancreatic cancer cell lines in vitro and in two orthotopic models. We also compared the effects of NT1721 to clinically used hedgehog inhibitors and the standard-of-care drug, gemcitabine. The effect of NT1721 on hedgehog/GLI signaling was assessed by determining the expression of GLI and GLI target genes both in vitro and in vivo.ResultsNT1721 displayed IC50 values in the submicromolar range in multiple pancreatic cancer cell lines, while largely sparing normal pancreatic epithelial cells. NT1721 attenuated hedgehog/GLI signaling through downregulation of GLI1/2 transcription factors and their downstream target genes, which reduced cell proliferation and invasion in vitro and significantly decreased tumor growth and liver metastasis in two preclinical orthotopic mouse models of pancreatic cancer. Importantly, treatment with NT1721 significantly improved survival times of mice with pancreatic cancer compared to the standard-of-care drug, gemcitabine.ConclusionsFavorable therapeutics properties, i.e. 10-fold lower IC50 values than clinically used hedgehog inhibitors (vismodegib, erismodegib), a 90% reduction in liver metastasis and significantly better survival times compared to the standard-of-care drug, gemcitabine, provide a rational for testing NT1721 in the clinic either as a single agent or possibly in combination with gemcitabine or other therapeutic agents in PDAC patients overexpressing GLI1/2. This could potentially result in promising new treatment options for patients suffering from this devastating disease
Retardation Terms in The One-Gluon Exchange Potential
It is pointed out that the retardation terms given in the original
Fermi-Breit potential vanish in the center of mass frame. The retarded
one-gluon exchange potential is rederived in this paper from the
three-dimensional one-gluon exchange kernel which appears in the exact
three-dimensional relativistic equation for quark-antiquark bound states. The
retardation part of the potential given in the approximation of order
is shown to be different from those derived in the previous literature. This
part is off-shell and does no longer vanish in the center of mass frame
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