7,411 research outputs found
Primordial Nucleosynthesis, Cosmic Microwave Background and Neutrinos
We report the results of a recent likelihood analysis combining the
primordial nucleosynthesis and the BOOMERanG and MAXIMA-1 data on cosmic
microwave background radiation anisotropies. We discuss the possible
implications for relic neutrino background of a high value for the baryonic
matter content of the universe, larger than what is expected in a standard
nucleosynthesis scenario.Comment: 3 pages, 1 figure, some typos corrected, one reference added,
presented by G. Mangano at NOW 2000, Europhysics Neutrino Oscillation
Workshop, Otranto 200
Rotor burst protection program initial test results, phase 4 Final report
High speed photographic recording of turbine wheel failure in containment devic
Re: "Soft tissue profile after distal molar movement with a pendulum K-loop appliance versus cervical headgear: a statistical consideration", by O. Polat-Ozsoy, A. Gokcelik, A. Gungor-Acar, B.H. Kircelli. The Angle Orthodontist 2008;78(Mar):317-323.
Radiative quarkonium decays and the NMSSM Higgs interpretation of the HyperCP Sigma+ --> p mu+mu- events
We study the potential of radiative decays of the Upsilon(1S) and of the phi
mesons to search for a light pseudoscalar Higgs boson, proposed as a possible
interpretation of Sigma+ --> p mu+mu- events observed by the HyperCP
collaboration at Fermilab. We conclude that the detection of this signal should
certainly be possible with the current CLEO Upsilon(1S) data, and is within the
reach of KLOE in at least part of the range of couplings suggested by the
HyperCP findings.Comment: 6 pages, no figure
Rotor burst protection program: Statistics on aircraft gas turbine engine rotor failures that occurred in US commercial aviation during 1975
Statistics on gas turbine rotor failures that have occurred in U.S. commercial aviation during 1975 are presented. The compiled data were analyzed to establish: (1) The incidence of rotor failures and the number of contained and uncontained rotor bursts; (2) The distribution of rotor bursts with respect to engine rotor component; i.e., fan, compressor or turbine; (3) The type of rotor fragment (disk, rim or blade) typically generated at burst; (4) The cause of failure; (5) The type of engines involved; and (6) The flight condition at the time of failure
Generalized Gluon Currents and Applications in QCD
We consider the process containing two quark lines and an arbitrary number of
gluons in a spinor helicity framework. A current with two off-shell gluons
appears in the amplitude. We first study this modified gluon current using
recursion relations. The recursion relation for the modified gluon current is
solved for the case of like-helicity gluons. We apply the modified gluon
current to compute the amplitude for in the like-helicity gluon case.Comment: 80 pages, 2 figures (appended in pictex), CLNS 91/112
Implication of the proton-deuteron radiative capture for Big Bang Nucleosynthesis
The astrophysical -factor for the radiative capture He in
the energy-range of interest for Big Bang Nucleosynthesis (BBN) is calculated
using an {\it ab-initio} approach. The nuclear Hamiltonian retains both two-
and three-nucleon interactions - the Argonne and the Urbana IX,
respectively. Both one- and many-body contributions to the nuclear current
operator are included. The former retain for the first time, besides the
leading order contribution ( is the nucleon mass), also the next-to-leading
order term, proportional to . The many-body currents are constructed in
order to satisfy the current conservation relation with the adopted Hamiltonian
model. The hyperspherical harmonics technique is applied to solve the
bound and scattering states. A particular attention is used in this second case
in order to obtain, in the energy range of BBN, an uncertainty on the
astrophysical -factor of the order or below 1 %. Then, in this energy
range, the -factor is found to be 10 % larger than the currently
adopted values.Part of this increase (1-3 %) is due to the one-body
operator, while the remaining is due to the new more accurate scattering wave
functions. We have studied the implication of this new determination for the
He -factor on deuterium primordial abundance. We find that
the predicted theoretical value for H/H is in excellent agreement with its
experimental determination, using the most recent determination of baryon
density of Planck experiment, and with a standard number of relativistic
degrees of freedom during primordial nucleosynthesis.Comment: 5 pages, 2 figures, submitted to Phys. Rev. Let
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