16,536 research outputs found
LHCb pentaquarks in constituent quark models
The recently discovered and states at LHCb have
masses close to the and thresholds,
respectively, which suggest that they may have significant meson-baryon
molecular components. We analyze these states in the framework of a constituent
quark model which has been applied to a wide range of hadronic observables,
being the model parameters, therefore, completely constrained.
The and are studied as molecular states composed
by charmed baryons and open charm mesons. Several bound states with the proper
binding energy are found in the and
channels. We discuss the possible assignments of these states from their decay
widths. Moreover, two more states are predicted, associated with the and thresholds.Comment: 5 pages, 2 table
Relation-based Galois connections: towards the residual of a relation
Inma P. Cabrera, Pablo Cordero, Manuel Ojeda-Aciego, Relation-based Galois connections: towards the residual of a relation, CMMSE 2017: Proceedings of the 17th International Conference on Mathematical Methods in Science and Engineering ( ISBN: 978-84-617-8694-7) , pp. 469--475We explore a suitable generalization of the notion of Galois connection in which their components are binary relations. Many different approaches are possible depending both on the (pre-)order relation between subsets in the underlying powerdomain and the chosen type of relational composition.Universidad de Málaga. Campus de Excelencia Internacional AndalucÃa Tech
Ge-substitutional defects and the r3xr3 <--> 3x3 transition in alpha--SnGe(111)
The structure and energetics of Ge substitutional defects on the
alpha-Sn/Ge(111) surface are analyzed using Density Functional Theory (DFT)
molecular dynamics (MD) simulations. An isolated Ge defect induces a very local
distortion of the 3x3 reconstruction, confined to a significant downwards
displacement (-0.31 A) at the defect site and a modest upward displacement
(0.05 A) of the three Sn nearest neighbours with partially occupied dangling
bonds. Dynamical fluctuations between the two degenerate ground states yield
the six-fold symmetry observed around a defect in the experiments at room
temperature. Defect-defect interactions are controlled by the energetics of the
deformation of the 3x3 structure: They are negligible for defects on the
honeycomb lattice and quite large for a third defect on the hexagonal lattice,
explaining the low temperature defect ordering.Comment: 4 pages, Revtex, 7 Encapsulated Postscript figures, uses epsf.sty.
Submitted to Phys. Rev. Let
Heavy mesons in the Quark Model
Since the discovery of the , the quark model was very successful in
describing the spectrum and properties of heavy mesons including only
components. However since 2003, with the discovery of the , many
states that can not be accommodated on the naive quark model have been
discovered, and they made unavoidable to include higher Fock components on the
heavy meson states. We will give an overview of the success of the quark model
for heavy mesons and point some of the states that are likely to be more
complicated structures such as meson-meson molecules.Comment: Contribution to the Proceedings of the 15th International Workshop on
Meson Physics - MESON201
Puzzles in quarkonium hadronic transitions with two pion emission
The anomalously large rates of some hadronic transitions from quarkonium are
studied using QCD multipole expansion (QCDME) in the framework of a constituent
quark model which has been successful in describing hadronic phenomenology. The
hybrid intermediate states needed in the QCDME method are calculated in a
natural extension of our constituent quark model based on the Quark Confining
String (QCS) scheme. Some of the anomalies are explained due to the presence of
an hybrid state with a mass near the mass of the decaying resonance whereas
other are justified by the presence of molecular components in the wave
function. Some unexpected results are pointed out.Comment: Conference proceedings of the XI Quark Confinement and the Hadron
Spectrum (CONFINEMENT XI). Saint Petersburg (Russia) from 8 to 12 September
201
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