74 research outputs found
Efimov physics in bosonic atom-trimer scattering
Bosonic atom-trimer scattering is studied in the unitary limit using
momentum-space equations for four-particle transition operators. The impact of
the Efimov effect on the atom-trimer scattering observables is explored and a
number of universal relations is established. Positions and widths of tetramer
resonances are determined. Trimer relaxation rate constant is calculated.Comment: Added results for the trimer relaxation rate constan
Renormalization group study of the four-body problem
We perform a renormalization group analysis of the non-relativistic
four-boson problem by means of a simple model with pointlike three- and
four-body interactions. We investigate in particular the unitarity point where
the scattering length is infinite and all energies are at the atom threshold.
We find that the four-body problem behaves truly universally, independent of
any four-body parameter. Our findings confirm the recent conjectures of Platter
et al. and von Stecher et al. that the four-body problem is universal, now also
from a renormalization group perspective. We calculate the corresponding
relations between the four- and three-body bound states, as well as the full
bound state spectrum and comment on the influence of effective range
corrections.Comment: 11 pages, 6 figures; v2: revised and published versio
Four-nucleon scattering: Ab initio calculations in momentum space
The four-body equations of Alt, Grassberger and Sandhas are solved for \nH
scattering at energies below three-body breakup threshold using various
realistic interactions including one derived from chiral perturbation theory.
After partial wave decomposition the equations are three-variable integral
equations that are solved numerically without any approximations beyond the
usual discretization of continuum variables on a finite momentum mesh. Large
number of two-, three- and four-nucleon partial waves are considered until the
convergence of the observables is obtained. The total \nH cross section data
in the resonance region is not described by the calculations which confirms
previous findings by other groups. Nevertheless the numbers we get are slightly
higher and closer to the data than previously found and depend on the choice of
the two-nucleon potential. Correlations between the deficiency in \nd
elastic scattering and the total \nH cross section are studied.Comment: Corrected Eq. (10
Negative parity tetraquarks with the open charm
The relativistic four-quark equations are found in the framework of
coupled-channel formalism. The dynamical mixing of the meson-meson states with
the four-quark states is considered. The four-quark amplitudes of the negative
parity tetraquarks including the quarks of three flavors (u, d, s) and the
charmed quark are constructed. The poles of these amplitudes determine the
masses of tetraquarks. The mass values of low-lying tetraquarks with the
spin-parity JP=0-,1-,2-,3- are calculated.Comment: 18 pages, pd
Faddeev-type calculations of few-body nuclear reactions including Coulomb interaction
The method of screening and renormalization is used to include the Coulomb
interaction between the charged particles in the description of few-body
nuclear reactions. Calculations are done in the framework of Faddeev-type
equations in momentum-space. The reliability of the method is demonstrated. The
Coulomb effect on observables is discussed.Comment: Proceedings of the 4th Asia-Pacific Conference on Few-Body Problems
in Physics (APFB08), Depok, Indonesia, August 19 - 23, 2008, to be published
in Mod. Phys. Lett.
Relativistic five-quark equations and negative parity pentaquarks
The relativistic five-quark equations are found in the framework of the
dispersion relation technique. The solutions of these equations using the
method based on the extraction of the leading singularities of the amplitudes
are obtained. The five-quark amplitudes for the low-lying pentaquarks including
the u, d, s- quarks are calculated. The poles of these amplitudes determine the
masses of the negative parity pentaquarks with I = 0, 1 and spin 3/2-, 5/2-.
The mass of the lowest pentaquark with I = 0 and spin 3/2- is equal to 1514
MeV.Comment: 18 pages, pdf, published versio
Binding and structure of tetramers in the scaling limit
The momentum-space structure of the Faddeev-Yakubovsky (FY)components of
weakly-bound tetramers is investigated at the unitary limit using a
renormalized zero-range two-body interaction. The results, obtained by
considering a given trimer level with binding energy , provide further
support to a universal scaling function relating the binding energies of two
successive tetramer states. The correlated scaling between the tetramer
energies comes from the sensitivity of the four-boson system to a short-range
four-body scale. Each excited th tetramer energy moves as the
short-range four-body scale changes, while the trimer properties are kept
fixed, with the next excited tetramer emerging from the
atom-trimer threshold for a universal ratio , which does not depend on . We show that both
channels of the FY decomposition [atom-trimer (type) and dimer-dimer
(type)] present high momentum tails, which reflect the short-range
four-body scale. We also found that the channel is favored over channel
at low momentum when the four-body momentum scale largely overcomes the
three-body one.Comment: To appear in PR
The Four-Boson System with Short-Range Interactions
We consider the non-relativistic four-boson system with short-range forces
and large scattering length in an effective quantum mechanics approach. We
construct the effective interaction potential at leading order in the large
scattering length and compute the four-body binding energies using the
Yakubovsky equations. Cutoff independence of the four-body binding energies
does not require the introduction of a four-body force. This suggests that two-
and three-body interactions are sufficient to renormalize the four-body system.
We apply the equations to 4He atoms and calculate the binding energy of the 4He
tetramer. We observe a correlation between the trimer and tetramer binding
energies similar to the Tjon line in nuclear physics. Over the range of binding
energies relevant to 4He atoms, the correlation is approximately linear.Comment: 23 pages, revtex4, 5 PS figures, discussion expanded, results
unchange
S-wave bottom tetraquarks
The relativistic four-quark equations are found in the framework of
coupled-channel formalism. The dynamical mixing of the meson-meson states with
the four-quark states is considered. The four-quark amplitudes of the
tetraquarks, including , , and bottom quarks, are constructed. The
poles of these amplitudes determine the masses and widths of -wave bottom
tetraquarks.Comment: 8 pages, late
Relativistic five-quark equations and u, d- pentaquark spectroscopy
The relativistic five-quark equations are found in the framework of the
dispersion relation technique. The five-quark amplitudes for the low-lying
pentaquarks including u, d quarks are calculated. The poles of the five-quark
amplitudes determine the masses of the lowest pentaquarks. The calculation of
pentaquark amplitudes estimates the contributions of four subamplitudes. The
main contributions to the pentaquark amplitude are determined by the
subamplitudes, which include the meson states M.Comment: 21 pages, pd
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