1,426 research outputs found
Of autoregressive continuous time model parameters estimation
This article revisits a sequential approach to the estimation of the parameter in a first-order autoregressive model (AR(1)) with continuous time. There is provided a numerical study to get a results of sequential estimations of the parameter in first-order autoregressive model with continuous time and is computed a stopping rule and the optimal time of observations. Also there is provided a comparing analysis of estimation results with using the sequential approach both the optimal time of observations
neutron strength in the isotones and the Cr()Cr reaction
We performed a measurement of the CrCr reaction at 16 MeV
using the Florida State University Super-Enge Split-Pole Spectrograph (SE-SPS)
and observed 26 states. While all of the states observed here had been seen in
previous experiments, we changed five assignments from those
reported previously and determined values for nine states that had not had
such assignments made previously.
The neutron strength observed in Cr in the present work and
in the isotones Ca, Ti, and Fe via
reactions is much smaller than the sum rule for this strength. Most of the
observed strength in these nuclei is located in states near 4 MeV
excitation energy. The remaining strength may be located in the
continuum or may be fragmented among many bound states. A covariant density
functional theory calculation provides support for the hypothesis that the
neutron orbit is unbound in Cr. The (He) reaction
may provide a more sensitive probe for the missing neutron strength.
In addition, particle- coincidence experiments may help resolve some
remaining questions in this nucleus.Comment: 15 pages, 5 figures. arXiv admin note: text overlap with
arXiv:2212.0438
Investigation of octupole collectivity near the shape-transitional point
Enhanced octupole collectivity is expected in the neutron-deficient Ge, Se
and Kr isotopes with neutron number and has indeed been observed
for Ge. Shape coexistence and configuration mixing are, however, a
notorious challenge for theoretical models trying to reliably predict octupole
collectivity in this mass region, which is known to feature rapid shape changes
with changing nucleon number and spin of the system. To further investigate the
microscopic configurations causing the prolate-oblate-triaxial shape transition
at and their influence on octupole collectivity, the rare
isotopes Se and Kr were studied via inelastic proton
scattering in inverse kinematics. While significantly enhanced octupole
strength of Weisskopf units (W.u.) was observed for Se, only
strengths of W.u. were observed for Kr. In combination with
existing data, the new data clearly question a simple origin of enhanced
octupole strengths around . The present work establishes two regions of
distinct octupole strengths with a sudden strength increase around the
shape transitional point
The {\eta}'-carbon potential at low meson momenta
The production of mesons in coincidence with forward-going
protons has been studied in photon-induced reactions on C and on a
liquid hydrogen (LH) target for incoming photon energies of 1.3-2.6 GeV at
the electron accelerator ELSA. The mesons have been identified
via the decay
registered with the CBELSA/TAPS detector system. Coincident protons have been
identified in the MiniTAPS BaF array at polar angles of . Under these kinematic constraints the
mesons are produced with relatively low kinetic energy (
150 MeV) since the coincident protons take over most of the momentum of the
incident-photon beam. For the C-target this allows the determination of the
real part of the -carbon potential at low meson momenta by
comparing with collision model calculations of the kinetic energy
distribution and excitation function. Fitting the latter data for
mesons going backwards in the center-of-mass system yields a potential depth of
V = (44 16(stat)15(syst)) MeV, consistent with earlier
determinations of the potential depth in inclusive measurements for average
momenta of 1.1 GeV/. Within the experimental
uncertainties, there is no indication of a momentum dependence of the
-carbon potential. The LH data, taken as a reference to check
the data analysis and the model calculations, provide differential and integral
cross sections in good agreement with previous results for
photoproduction off the free proton.Comment: 9 pages, 13 figures. arXiv admin note: text overlap with
arXiv:1608.0607
Photoproduction of eta mesons from the neutron: cross sections and double polarization observable E
Photoproduction of mesons from neutrons} \abstract{Results from
measurements of the photoproduction of mesons from quasifree protons and
neutrons are summarized. The experiments were performed with the CBELSA/TAPS
detector at the electron accelerator ELSA in Bonn using the
decay. A liquid deuterium target was used for the
measurement of total cross sections and angular distributions. The results
confirm earlier measurements from Bonn and the MAMI facility in Mainz about the
existence of a narrow structure in the excitation function of . The current angular distributions show a forward-backward
asymmetry, which was previously not seen, but was predicted by model
calculations including an additional narrow state. Furthermore, data
obtained with a longitudinally polarized, deuterated butanol target and a
circularly polarized photon beam were analyzed to determine the double
polarization observable . Both data sets together were also used to extract
the helicity dependent cross sections and . The
narrow structure in the excitation function of
appears associated with the helicity-1/2 component of the reaction
Les Houches 2015: Physics at TeV colliders - new physics working group report
We present the activities of the 'New Physics' working group for the 'Physics
at TeV Colliders' workshop (Les Houches, France, 1-19 June, 2015). Our report
includes new physics studies connected with the Higgs boson and its properties,
direct search strategies, reinterpretation of the LHC results in the building
of viable models and new computational tool developments. Important signatures
for searches for natural new physics at the LHC and new assessments of the
interplay between direct dark matter searches and the LHC are also considered.Comment: Proceedings of the New Physics Working Group of the 2015 Les Houches
Workshop, Physics at TeV Colliders, Les Houches 1-19 June 2015. 197 page
Measurement of pi^0 photoproduction on the proton at MAMI C
Differential cross sections for the gamma p -> pi^0 p reaction have been
measured with the A2 tagged-photon facilities at the Mainz Microtron, MAMI C,
up to the center-of-mass energy W=1.9 GeV. The new results, obtained with a
fine energy and angular binning, increase the existing quantity of pi^0
photoproduction data by ~47%. Owing to the unprecedented statistical accuracy
and the full angular coverage, the results are sensitive to high partial-wave
amplitudes. This is demonstrated by the decomposition of the differential cross
sections in terms of Legendre polynomials and by further comparison to model
predictions. A new solution of the SAID partial-wave analysis obtained after
adding the new data into the fit is presented.Comment: 13 pages, 12 figures, 1 tabl
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