529 research outputs found
Electromagnetic form factors of the meson in a light-front constituent quark model
The electromagnetic form factors of the meson are evaluated adopting a
relativistic constituent quark model based on the light-front formalism, and
using a meson wave function with the high-momentum tail generated by the
one-gluon-exchange interaction. The breakdown of the rotational covariance for
the one-body component of the current operator is investigated and the
sensitivity of the ratio of the -meson form factors to the pion (charge)
form factor to the spin-dependent component of the effective
interaction is illustrated.Comment: 8 pages, latex file, 4 figures available as a separate .uu fil
Hard Constituent Quarks and Electroweak Properties of Pseudoscalar Mesons
The high momentum components generated in the wave function of pseudoscalar
mes* by the one-gluon-exchange interaction are investigated within a
relativistic constituent quark model. Adopting the light-cone formalism, the
sensitivity of the weak decay constant and the charge form factor to hard
constituent quarks is illustrated.Comment: 11 pages and 5 figs. (to be requested), LaTeX, INFN-ISS 94/3. To
appear in Physics Lett.
Role of non-coding RNAs in maintaining primary airway smooth muscle cells
BACKGROUND: The airway smooth muscle (ASM) cell maintains its own proliferative rate and contributes to the inflammatory response in the airways, effects that are inhibited by corticosteroids, used in the treatment of airways diseases. OBJECTIVE: We determined the differential expression of mRNAs, microRNAs (miRNAs) and long noncoding RNA species (lncRNAs) in primary ASM cells following treatment with a corticosteroid, dexamethasone, and fetal calf serum (FCS). METHODS: mRNA, miRNA and lncRNA expression was measured by microarray and quantitative real-time PCR. RESULTS: A small number of miRNAs (including miR-150, â371-5p, â718, â940, â1181, â1207-5p, â1915, and â3663-3p) were decreased following exposure to dexamethasone and FCS. The mRNA targets of these miRNAs were increased in expression. The changes in mRNA expression were associated with regulation of ASM actin cytoskeleton. We also observed changes in expression of lncRNAs, including natural antisense, pseudogenes, intronic lncRNAs, and intergenic lncRNAs following dexamethasone and FCS. We confirmed the change in expression of three of these, LINC00882, LINC00883, PVT1, and its transcriptional activator, c-MYC. We propose that four of these lincRNAs (RP11-46A10.4, LINC00883, BCYRN1, and LINC00882) act as miRNA âspongesâ for 4 miRNAs (miR-150, â371-5p, â940, â1207-5p). CONCLUSION: This in-vitro model of primary ASM cell phenotype was associated with the regulation of several ncRNAs. Their identification allows for in-vitro functional experimentation to establish causality with the primary ASM phenotype, and in airway diseases such as asthma and chronic obstructive pulmonary disease (COPD)
Combined CI+MBPT calculations of energy levels and transition amplitudes in Be, Mg, Ca, and Sr
Configuration interaction (CI) calculations in atoms with two valence
electrons, carried out in the V(N-2) Hartree-Fock potential of the core, are
corrected for core-valence interactions using many-body perturbation theory
(MBPT). Two variants of the mixed CI+MBPT theory are described and applied to
obtain energy levels and transition amplitudes for Be, Mg, Ca, and Sr
Dalitz plot analysis of D_s+ and D+ decay to pi+pi-pi+ using the K-matrix formalism
FOCUS results from Dalitz plot analysis of D_s+ and D+ to pi+pi-pi+ are
presented. The K-matrix formalism is applied to charm decays for the first time
to fully exploit the already existing knowledge coming from the light-meson
spectroscopy experiments. In particular all the measured dynamics of the S-wave
pipi scattering, characterized by broad/overlapping resonances and large
non-resonant background, can be properly included. This paper studies the
extent to which the K-matrix approach is able to reproduce the observed Dalitz
plot and thus help us to understand the underlying dynamics. The results are
discussed, along with their possible implications on the controversial nature
of the sigma meson.Comment: To be submitted to Phys.Lett.B A misprint corrected in formula
A simple model for the estimation of congenital malformation frequency in racially mixed populations
Search for and Using Genetic Programming Event Selection
We apply a genetic programming technique to search for the double Cabibbo
suppressed decays and .
We normalize these decays to their Cabibbo favored partners and find
\Lambda_c^+ \to p K^+ \pi^-\Lambda_c^+ \to p K^-
\pi^+ and D_s^+ \to K^+ K^+
\pi^-D_s^+ \to K^+ K^- \pi^+ where
the first errors are statistical and the second are systematic. Expressed as
90% confidence levels (CL), we find and respectively.
This is the first successful use of genetic programming in a high energy
physics data analysis.Comment: 10 page
Measurement of the D+ and Ds+ decays into K+K-K+
We present the first clear observation of the doubly Cabibbo suppressed decay
D+ --> K-K+K+ and the first observation of the singly Cabibbo suppressed decay
Ds+ --> K-K+K+. These signals have been obtained by analyzing the high
statistics sample of photoproduced charm particles of the FOCUS(E831)
experiment at Fermilab. We measure the following relative branching ratios:
Gamma(D+ --> K-K+K+)/Gamma(D+ --> K-pi+pi+) = (9.49 +/- 2.17(statistical) +/-
0.22(systematic))x10^-4 and Gamma(Ds+ --> K-K+K+)/Gamma(Ds+ --> K-K+pi+) =
(8.95 +/- 2.12(statistical) +2.24(syst.) -2.31(syst.))x10^-3.Comment: 10 pages, 8 figure
A Non-parametric Approach to the D+ to K*0bar mu+ nu Form Factors
Using a large sample of D+ -> K- pi+ mu+ nu decays collected by the FOCUS
photoproduction experiment at Fermilab, we present the first measurements of
the helicity basis form factors free from the assumption of spectroscopic pole
dominance. We also present the first information on the form factor that
controls the s-wave interference discussed in a previous paper by the FOCUS
collaboration. We find reasonable agreement with the usual assumption of
spectroscopic pole dominance and measured form factor ratios.Comment: 14 pages, 5 figures, and 2 tables. We updated the previous version by
changing some words, removing one plot, and adding two tables. These changes
are mostly stylisti
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