Search results for "continuum"
showing 10 items of 477 documents
Searching for new physics in leptonic decays of bottomonium
2002
New Physics can show up in various well-known processes already studied in the Standard Model, in particular by modifying decay rates to some extent. In this work, I examine leptonic decays of $\Upsilon$ vector resonances of bottomonium below $B\bar{B}$ production, subsequent to a magnetic dipole radiative structural transition of the vector resonance yielding a pseudoscalar continuum state, searching for the existence of a light Higgs-like neutral boson that would imply a slight but experimentally measurable breaking of lepton universality.
Nucleon Vector Strangeness Form Factors: Multi-pion Continuum and the OZI Rule
1997
We estimate the 3 \pi continuum contribution to the nucleon strange quark vector current form factors, including the effect of a 3 \pi \rho \pi resonance. We find the magnitude of this OZI-violating contribution to be comparable to that of typical OZI-allowed contributions. We also study the isoscalar electromagnetic form factors, and find that the presence of a \rho \pi resonance in the multi-pion continuum may generate an appreciable contribution.
A BeppoSAX study of the Galactic Z-source GX 340+0
2004
Abstract We present the results of a BeppoSAX broad band (0.1–200 keV) observation of the Z-source GX 340+0. The 1.8–30 keV continuum is well described by a blackbody ( kT BB ∼0.5 keV) plus a Comptonized component with seed photons temperature ∼ 1 keV and electron temperature ∼ 3 keV. A hard tail dominates the spectrum above 30 keV. It can be fitted using a bremsstrahlung component or, equivalently, a powerlaw (with a low-energy cutoff). We detect also a Gaussian line at ∼6.8 keV and an absorption edge at ∼9.2 keV. A low-energy (∼1 keV) unresolved feature needs further investigations.
Exclusive measurement of breakup reactions with the one-neutron halo nucleus11Be
2003
Electromagnetic and nuclear inelastic scattering of the halo nucleus ${}^{11}\mathrm{Be}$ have been investigated by a measurement of the one-neutron removal channel, utilizing a secondary ${}^{11}\mathrm{Be}$ beam with an energy of 520 MeV/nucleon impinging on lead and carbon targets. All decay products, i.e., ${}^{10}\mathrm{Be}$ fragments, neutrons, and $\ensuremath{\gamma}$ rays have been detected in coincidence. Partial cross sections for the population of ground and excited states in ${}^{10}\mathrm{Be}$ were determined for nuclear diffractive breakup as well as for electromagnetically induced breakup. The partial cross sections for ground-state transitions have been differentiated fur…
Quasielastic K-nucleus scattering
1996
Quasielastic K^+ - nucleus scattering data at q=290, 390 and 480 MeV/c are analyzed in a finite nucleus continuum random phase approximation framework, using a density-dependent particle-hole interaction. The reaction mechanism is consistently treated according to Glauber theory, keeping up to two-step inelastic processes. A good description of the data is achieved, also providing a useful constraint on the strength of the effective particle-hole interaction in the scalar-isoscalar channel at intermediate momentum transfers. We find no evidence for the increase in the effective number of nucleons participating in the reaction which has been reported in the literature.
Neutron capture cross sections for neutron-rich isotopes
1985
Average continuum (Hauser-Feshbach) and resonance (Breit-Wigner) neutron capture rates for neutron-rich isotopes, determined on the basis of recent experimental nuclear physics input parameters, are compared to earlier theoretical reaction rates commonly used in astrophysical model computations.
STUDIES OF 12C USING β-DECAYS
2008
The nuclear structure of states in 12 C have been a subject of interest for both theory and experiment since the early days of nuclear physics. Many open questions remain, especially concerning the existence and properties of 0+ and 2+ states in the triple alpha continuum. A series of experiments have been performed using β-decay of 12 N and 12 B to probe these states. The latest experiment was performed at KVI using an implantation method, measuring the sum energy of the three α-particles directly. Preliminary results from this experiment will be presented.
Bifurcations of phase portraits of a Singular Nonlinear Equation of the Second Class
2014
Abstract The soliton dynamics is studied using the Frenkel Kontorova (FK) model with non-convex interparticle interactions immersed in a parameterized on-site substrate potential. The case of a deformable substrate potential allows theoretical adaptation of the model to various physical situations. Non-convex interactions in lattice systems lead to a number of interesting phenomena that cannot be produced with linear coupling alone. In the continuum limit for such a model, the particles are governed by a Singular Nonlinear Equation of the Second Class. The dynamical behavior of traveling wave solutions is studied by using the theory of bifurcations of dynamical systems. Under different para…
A decade of SN 1993J : discovery of radio wavelength effects in the expansion rate
2009
We studied the growth of the shell-like radio structure of supernova SN 1993J in M 81 from September 1993 to October 2003 with very-long-baseline interferometry (VLBI) observations at the wavelengths of 3.6, 6, and 18 cm. We developed a method to accurately determine the outer radius (R) of any circularly symmetric compact radio structure such as SN 1993J. The source structure of SN 1993J remains circularly symmetric (with deviations from circularity under 2%) over almost 4000 days. We characterize the decelerated expansion of SN 1993J until approximately day 1500 after explosion with an expansion parameter m = 0.845 ± 0.005 (R ∝ tm). However, from that day onwards the expansion differs whe…
Continuum generation by dark solitons
2009
We demonstrate that the dark soliton trains in optical fibers with a zero of the group velocity dispersion can generate broad spectral distribution (continuum) associated with the resonant dispersive radiation emitted by solitons. This radiation is either enhanced or suppressed by the Raman scattering depending on the sign of the third order dispersion.