303 research outputs found
Astrophysical factor for the reaction from -matrix analysis and asymptotic normalization coefficient for . Is any fit acceptable?
The reaction provides a path from the CN
cycle to the CNO bi-cycle and CNO tri-cycle. The measured astrophysical factor
for this reaction is dominated by resonant capture through two strong
resonances at and 962 keV and direct capture to
the ground state. Recently, a new measurement of the astrophysical factor for
the reaction has been published [P. J.
LeBlanc {\it et al.}, Phys. Rev. {\bf C 82}, 055804 (2010)]. The analysis has
been done using the -matrix approach with unconstrained variation of all
parameters including the asymptotic normalization coefficient (ANC). The best
fit has been obtained for the square of the ANC fm,
which exceeds the previously measured value by a factor of . Here we
present a new -matrix analysis of the Notre Dame-LUNA data with the fixed
within the experimental uncertainties square of the ANC
fm. Rather than varying the ANC we add the contribution from a
background resonance that effectively takes into account contributions from
higher levels. Altogether we present 8 fits, five unconstrained and three
constrained. In all the fits the ANC is fixed at the previously determined
experimental value fm. For the unconstrained fit with
the boundary condition , where is the energy of the
second level, we get keVb and normalized , i.e. the result which is similar to [P. J. LeBlanc {\it et
al.}, Phys. Rev. {\bf C 82}, 055804 (2010)]. From all our fits we get the range
keVb which overlaps with the result of [P. J.
LeBlanc {\it et al.}, Phys. Rev. {\bf C 82}, 055804 (2010)]. We address also
physical interpretation of the fitting parameters.Comment: Submitted to PR
Theory of deuteron stripping. From surface integrals to generalized -matrix approach
There are two main reasons for absence of the practical theory of stripping
to resonance states which could be used by experimental groups: numerical
problem of the convergence of the DWBA matrix element when the full transition
operator is included and it is unclear what spectroscopic information can be
extracted from the analysis of transfer reactions populating the resonance
states. The purpose of this paper is to address both questions. The theory of
the deuteron stripping is developed, which is based on the post continuum
discretized coupled channels (CDCC) formalism going beyond of the DWBA and
surface integral formulation of the reaction theory [A. S. Kadyrov et al., Ann.
Phys. {\bf 324}, 1516 (2009)]. First, the formalism is developed for the DWBA
and then extended to the CDCC formalism, which is ultimate goal of this work.
The CDCC wave function takes into account not only the initial elastic
channel but also its coupling to the deuteron breakup channel
missing in the DWBA. Stripping to both bound states and resonances are
included. The convergence problem for stripping to resonance states is solved
in the post CDCC formalism. The reaction amplitude is parametrized in terms of
the reduced width amplitudes (ANCs), inverse level matrix, boundary condition
and channel radius, that is the same parameters which are used in the
conventional -matrix method. For stripping to resonance states many-level,
one and two-channel cases are considered. The theory provides a consistent tool
to analyze both binary resonant reactions and deuteron stripping in terms of
the same parameters.Comment: 37 page
Coulomb renormalization and ratio of proton and neutron asymptotic normalization coefficients for mirror nuclei
Asymptotic normalization coefficients (ANCs) are fundamental nuclear
constants playing important role in nuclear reactions, nuclear structure and
nuclear astrophysics. In this paper the physical reasons of the Coulomb
renormalization of the ANC are addressed. Using Pinkston-Satchler equation the
ratio for the proton and neutron ANCs of mirror nuclei is obtained in terms of
the Wronskians from the radial overlap functions and regular solutions of the
two-body Schr\"odinger equation with the short-range interaction excluded. This
ratio allows one to use microscopic overlap functions for mirror nuclei in the
internal region, where they are the most accurate, to correctly predict the
ratio of the ANCs for mirror nuclei, which determine the amplitudes of the
tails of the overlap functions. Calculations presented for different nuclei
demonstrate the Coulomb renormalization effects and independence of the ratio
of the nucleon ANCs for mirror nuclei on the channel radius. This ratio is
valid both for bound states and resonances. One of the goals of this paper is
to draw attention on the possibility to use the Coulomb renormalized ANCs
rather than the standard ones especially when the standard ANCs are too large.Comment: 20 pages, 14 figure
Bound, virtual and resonance -matrix poles from the Schr\"odinger equation
A general method, which we call the potential -matrix pole method, is
developed for obtaining the -matrix pole parameters for bound, virtual and
resonant states based on numerical solutions of the Schr\"odinger equation.
This method is well-known for bound states. In this work we generalize it for
resonant and virtual states, although the corresponding solutions increase
exponentially when . Concrete calculations are performed for the
ground and the first excited states of , the resonance
states (, ), low-lying states of and
, and the subthreshold resonances in the proton-proton system. We
also demonstrate that in the case the broad resonances their energy and width
can be found from the fitting of the experimental phase shifts using the
analytical expression for the elastic scattering -matrix. We compare the
-matrix pole and the -matrix for broad resonance in
Comment: 14 pages, 5 figures (figures 3 and 4 consist of two figures each) and
4 table
Experimental study of the decay PHI(1020)--->ETA+GAMMA in multi-photon final state
In the SND experiment at VEPP-2M e^+e^- collider the phi(1020) ---> eta+gamma
---> 3pi^0+gamma decay was studied. The branching ratio B(phi--->eta+gamma) =
(1.246 +- 0.025 +- 0.057)% was measured.Comment: 4 pages, 1 figure, 1 table, Submitted to JETP Let
{Once more about astrophysical factor for the reaction
Recently to study the radiative capture process a new measurement of the
dissociation in the field of has been reported in [F.
Hammache {\it et al.} Phys. Rev , 065803 (2010)]. However, the
dominance of the nuclear breakup over the Coulomb one prevented from obtaining
the information about the process from
the breakup data. The astrophysical factor has been calculated
within the two-body potential model with potentials determined from
the fits to the elastic scattering phase shifts. However, the
scattering phase shift itself doesn't provide a unique bound state
potential, which is the most crucial input when calculating the
astrophysical factor at astrophysical energies. In this work we emphasize an
important role of the asymptotic normalization coefficient (ANC) for
, which controls the overall normalization of
the peripheral process and is
determined by the adopted bound state potential. We demonstrate that
the ANC previously determined from the elastic scattering -wave
phase shift in [Blokhintsev {\it et. al} Phys. Rev. {\bf C 48}, 2390 (1993)]
gives , which is at low energies about 38% lower than the one
reported in [F. Hammache {\it et al.} Phys. Rev , 065803 (2010)].
We recalculate also the reaction rates, which are also lower than those
obtained in [F. Hammache {\it et al.} Phys. Rev , 065803 (2010)].Comment: 6 pages and 2 figure
New high order relations between physical observables in perturbative QCD
We exploit the fact that within massless perturbative QCD the same Green's
function determines the hadronic contribution to the decay width and the
moments of the cross section. This allows one to obtain relations
between physical observables in the two processes up to an unprecedented high
order of perturbative QCD. A precision measurement of the decay width
allows one then to predict the first few moments of the spectral density in
annihilations integrated up to with high accuracy.
The proposed tests are in reach of present experimental capabilities.Comment: 7 pages, Latex, no figure
The Radiative Decay of Vector Mesons
In this paper, radiative decays , are studied
systematically in the U(3)_L\timesU(3)_R chiral theory of mesons. The
theoretical differential spectrum with respect to photon energy and branch
ratio for agree well with the experimental data.
Differential spectrums and branch ratios for are predicted. The process is relevant to precision measurment of CP-violation
parameters in the kaon systerm at a -factory. We give a complete estimate
of the branch ratio for this decay process by including scalar resonance poles, nonresonant smooth amplitude and an abnormal parity process with
pole which hasn't been considered before. We conclude that processes with
intermediate do not pose a potential background problem for CP violation experiments.Comment: Revtex file, 12 pages, 9 eps figure
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