18,511 research outputs found
Partonske raspodjele u nukleonu na osnovi relativistiÄkog modela neovisnih kvarkova
At a low resolution scale with Q2 = Āµ2 corresponding to the nucleon bound state, deep inelastic unpolarized structure functions F1(x, Āµ2) and F2(x, Āµ2) are derived, with correct support using the symmetric part of the hadronic tensor under some simplifying assumptions in the Bjorken limit. For doing this, the nucleon in its ground state has been represented by a suitably constructed momentum wave packet of its valence quarks in their appropriate SU(6) spin flavour configuration, with the momentum probability amplitude taken phenomenologically in reference to the independent quark model of scalar-vector harmonic potential. The valence quark distribution functions uv(x, Āµ2) and dv(x, Āµ2), extracted from the structure function F1(x, Āµ2) in a parton model interpretation, satisfy normalization constraints as well as the momentum sum-rule requirements at a bound state scale of Āµ2 = 0.1 GeV2. QCD evolution of these distribution functions taken as the inputs, yields at Q2 0 = 15 GeV2, xuv(x, Q2 0) and xdv(x, Q2 0) in good qualitative agreement with the experimental data. The gluon distribution G(x, Q2 0) and the sea-quark distribution qs(x, Q2 0), which are dynamically generated using the leading order renormalization group equation, also match reasonably well with the available experimental data.Upotrebom simetriÄnog dijela hadronskog tenzora, uz pojednostavljenje u Bjorkenovoj granici, izveli smo duboko-neelastiÄne strukturne funkcije bez polarizacije F1(x, Āµ2) i F2(x, Āµ2) za slabo razluÄivanje sa Q2 = Āµ2, Å”to odgovara vezanom nukleonskom stanju. Nukleon se u svom osnovnom stanju predstavlja pogodno odabranim impulsnim valnim paketom svojih valentnih kvarkova u prikladnom SU(6) spinskom okusnom sklopu, a impulsne amplitude vjerojatnosti uzimaju se fenomenoloÅ”ki prema modelu neovisnih kvarkova skalarno-vektorskog harmoniÄkog potencijala. Iz strukturne funkcije F1(x, Āµ2) izvode se funkcije raspodjele valentnih kvarkova uv(x, Āµ2) i dv(x, Āµ2) u partonskom modelu, i one zadovoljavaju uvjete normalizacije i impulsnog zbrojnog pravila na ljestvici vezanja Āµ2 = 0.1 GeV2. PolazeÄi od tih funkcija za Q2 0 = 15 GeV2, QCD razvoj daje xuv(x, Q2 0) i xdv(x, Q2 0), u dobrom skladu s mjernim podacima. Gluonska G(x, Q2 0) i kvarkovska qs(x, Q2 0) raspodjela tvore se dinamiÄki upotrebom jednadžbe renormalizacijske grupe u prvom redu i takoÄer se dobro slažu s mjernim podacima
Resolution of puzzles from the LSND, KARMEN, and MiniBooNE experiments
This work has attempted to reconcile puzzling neutrino oscillation results
from the LSND, KARMEN and MiniBooNE experiments. We show that the LSND evidence
for oscillations, its long-standing
disagreement with the results from KARMEN, and the anomalous event excess
observed by MiniBooNE in and data could all be
explained by the existence of a heavy sterile neutrino (). All these
results are found to be consistent with each other assuming that the is
created in neutral-current interactions and decays radiatively into a
photon and a light neutrino. Assuming the is produced through mixing
with , the combined analysis of the LSND and MiniBooNe excess events
suggests that the mass is in the range from 40 to 80 MeV, the mixing
strength is , and the lifetime is
s. Surprisingly, this LSND-MiniBooNE parameters
window is found to be unconstrained by the results from the most sensitive
experiments searching for heavy neutrino. We set new limits on
for the LSND-MiniBooNE favorable mass region from the precision measurements of
the Michel spectrum by the TWIST experiment. The results obtained provide a
strong motivation for a sensitive search for the in a near future
decay or neutrino experiments, which fit well in the existing/planned
experimental programs at CERN or FNAL. The question of whether the heavy
neutrino is Dirac or Majorana particle is briefly discussed.Comment: 24 pages, 28 figures, version to appear in PR
Angular Steering for Proportional Navigation-commanded Surface-to-air Guided Missile
The paper briefly reviews the guidance laws and their implementation in surface-to-airmissiles. The trajectories for the line-of-sight and proportional navigation guidance laws arediscussed and the effect of steering on demand for increased lateral acceleration is appreciated.The mathematical model is then evolved to estimate the launch angle of the missile, ie, bearingand elevation, in the direction of the future position of the moving air target as well as thesteering commands in pitch and yaw planes in accordance with the proportional navigationguidance law, to enable collision with the target
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