2,431 research outputs found
New LHCb pentaquarks as hadrocharmonium states
New LHCb Collaboration results on pentaquarks with hidden charm [1] are
discussed. These results fit nicely in the hadrocharmonium pentaquark scenario
[2,3]. In the new data the old LHCb pentaquark splits into two
states and . We interpret these two almost degenerate
hadrocharmonium states with and as a result of
hyperfine splitting between hadrocharmonium states predicted in [2]. It arises
due to QCD multipole interaction between color-singlet hadrocharmonium
constituents. We improve the theoretical estimate of hyperfine splitting [2,3]
that is compatible with the experimental data. The new state finds
a natural explanation as a bound state of and a nucleon, with
, and binding energy 42 MeV. As a bound state of a spin-zero
meson and a nucleon, hadrocharmonium pentaquark does not experience
hyperfine splitting. We find a series of hadrocharmonium states in the vicinity
of the wide pentaquark that can explain its apparently large decay
width. We compare the hadrocharmonium and molecular pentaquark scenarios and
discuss their relative advantages and drawbacks.Comment: 10 page
Pentaquarks with hidden charm as hadroquarkonia
We consider hidden charm pentaquarks as hadroquarkonium states in a QCD
inspired approach. Pentaquarks arise naturally as bound states of quarkonia
excitations and ordinary baryons. The LHCb pentaquark is
interpreted as a -nucleon bound state with spin-parity . The
partial decay width MeV is calculated
and turned out to be in agreement with the experimental data for .
The pentaquark is predicted to be a member of one of the two almost
degenerate hidden-charm baryon octets with spin-parities .
The masses and decay widths of the octet pentaquarks are calculated. The widths
are small and comparable with the width of the pentaquark, and the
masses of the octet pentaquarks satisfy the Gell-Mann-Okubo relation.
Interpretation of pentaquarks as loosely bound and
deuteronlike states is also considered. We determine
quantum numbers of these bound states and calculate their masses in the
one-pion exchange scenario. The hadroquarkonium and molecular approaches to
exotic hadrons are compared and the relative advantages and drawbacks of each
approach are discussed.Comment: 33 pages, 2 figures, 3, tables; Minor changes, 2 references added;
Version published in Eur. Phys. J.
Large-scale Ferrofluid Simulations on Graphics Processing Units
We present an approach to molecular-dynamics simulations of ferrofluids on
graphics processing units (GPUs). Our numerical scheme is based on a
GPU-oriented modification of the Barnes-Hut (BH) algorithm designed to increase
the parallelism of computations. For an ensemble consisting of one million of
ferromagnetic particles, the performance of the proposed algorithm on a Tesla
M2050 GPU demonstrated a computational-time speed-up of four order of magnitude
compared to the performance of the sequential All-Pairs (AP) algorithm on a
single-core CPU, and two order of magnitude compared to the performance of the
optimized AP algorithm on the GPU. The accuracy of the scheme is corroborated
by comparing the results of numerical simulations with theoretical predictions
Measurement of the - mixing angle in and beams with GAMS- Setup
The results of mixing angle measurement for , mesons generated
in charge exchange reactions with and beams are preseneted.
When the , mesons are described in nonstrange(NS)--strange(S)
quark basis the and beams allow to study and
parts of the meson wave function. The cross section ratio at
(GeV/c) in the beam is , results in mixing angle . For
beam the ratio is . It was found that
gluonium content in is . The
experiment was carried out with GAMS-4 Setup.Comment: 6 pages, 4 figures, 1 table, to be submitted in European physical
journal C. Minor changes, the Bibliography extende
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