268 research outputs found
Are the new excited baryons negative parity states?
We calculate the mass and residue of the newly observed and
states with quantum numbers and
within QCD sum rules. Our predictions on masses are in good
agreement with the experimental results.Comment: 12 pages, 7 figures; typos corrected, appendix is adde
Light vector meson octet-decuplet baryon vertices in QCD
The strong coupling constants between light vector mesons and octet-decuplet
baryons are calculated in framework of the light cone QCD sum rules, taking
into account SU(3) flavor symmetry breaking effects. It is shown that all
strong coupling constants can be represented in terms of a single universal
function. Size of the SU(3) symmetry breaking effects are estimated.Comment: 27 pages, 6 figures, LaTeX formatte
Vector meson dominance and radiative decays of heavy spin-3/2 baryons to heavy spin--1/2 baryons
Using the calculated values of the strong coupling constants of the heavy
sextet spin-3/2 baryons to sextet and antitriplet heavy spin-1/2 baryons with
light mesons within the light cone QCD sum rules method, and vector meson
dominance assumption, the radiative decay widths are calculated. These widths
are compared with the "direct" radiative decay widths predicted in the
framework of the light cone QCD sum rules.Comment: 8 pages, no figures, LaTeX formatte
Semileptonic decays of pseudoscalar mesons to scalar "f_0" meson
The transition form factors of (D_s -> f_0 l nu), (D -> f_0 l nu) and (B_u ->
f_0 l nu) decays are calculated in 3-point QCD sum rule method, assuming that
"f_0" is a quark-antiquark state with a mixture of strange and light quarks.
The branching ratios of these decays are calculated in terms of the mixing
angle.Comment: 12 pages, 4 figures, LaTeX formatte
Dynamic walking features and improved walking performance in multiple sclerosis patients treated with fampridine (4-aminopyridine)
Background: Impaired walking capacity is a frequent confinement in Multiple Sclerosis (MS). Patients are affected by limitations in coordination, walking speed and the distance they may cover. Also abnormal dynamic walking patterns have been reported, involving continuous deceleration over time. Fampridine (4-aminopyridine), a potassium channel blocker, may improve walking in MS. The objective of the current study was to comprehensively examine dynamic walking characteristics and improved walking capacity in MS patients treated with fampridine. Methods: A sample of N = 35 MS patients (EDSS median: 4) underwent an electronic walking examination prior to (Time 1), and during treatment with fampridine (Time 2). Patients walked back and forth a distance of 25 ft for a maximum period of 6 min (6-minute 25-foot-walk). Besides the total distance covered, average speed on the 25-foot distance and on turns was determined separately for each test minute, at Time 1 and Time 2. Results: Prior to fampridine administration, 27/35 patients (77 %) were able to complete the entire 6 min of walking, while following the administration, 34/35 patients (97 %) managed to walk for 6 min. In this context, walking distance considerably increased and treatment was associated with faster walking and turning across all six test minutes (range of effect sizes: partial eta squared = .34-.72). Importantly, previously reported deceleration across test minutes was consistently observable at Time 1 and Time 2. Discussion: Fampridine administration is associated with improved walking speed and endurance. Regardless of a treatment effect of fampridine, the previously identified, abnormal dynamic walking feature, i.e. the linear decline in walking speed, may represent a robust feature. Conclusions: The dynamic walking feature might hence be considered as a candidate for a new outcome measure in clinical studies involving interventions other than symptomatic treatment, such as immune-modulating medication. Trial registration: DRKS00009228 (German Clinical Trials Register). Date obtained: 25.08.2015
Multipole Moments of Heavy Vector and Axial-Vector Mesons in QCD
The magnetic and quadrupole moments of the vector and axial-vector mesons
containing heavy quark are estimated within the light cone sum rules method.
Our predictions on magnetic moments for the vector mesons are compared with the
results obtained by other approaches
Charmed baryon and decays in light cone sum rules
The semileptonic and non-leptonic
, decays of
charmed baryon are studied within the light cone sum rules. The form
factors responsible for transitions are calculated using
the distribution amplitudes of baryon. With the obtained form
factors, the branching ratios of ,
, and decays are estimated. The results are compared with Belle data as well
as the findings of the other approaches
Constraints on Astro-unparticle Physics from SN 1987A
SN 1987A observations have been used to place constraints on the interactions
between standard model particles and unparticles. In this study we calculate
the energy loss from the supernovae core through scalar, pseudo scalar, vector,
pseudo vector unparticle emission from nuclear bremsstrahlung for degenerate
nuclear matter interacting through one pion exchange. In order to examine the
constraints on we considered the emission of scalar, pseudo
scalar, vector, pseudo vector and tensor through the pair annihilation process
. In addition we have re-examined other pair
annihilation processes. The most stringent bounds on the dimensionless coupling
constants for and are obtained from
nuclear bremsstrahlung process for the pseudo scalar and pseudo-vector
couplings and for
tensor interaction, the best limit on dimensionless coupling is obtained from
and we get .Comment: 12 pages, 2 postscript figure
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