1,721,091 research outputs found
Positive parity pentaquarks in a Goldstone boson exchange model
Get PDFpeer reviewedWe study the stability of the pentaquarks ,
and ( or ) of positive parity
in a constituent quark model based on Goldstone boson exchange interaction
between quarks. The pentaquark parity is the antiquark parity times that of a
quark excited to a p-shell. We show that the Goldstone boson exchange
interaction favors these pentaquarks much more than the negative parity ones of
the same flavour content but all quarks in the ground state. We find that the
nonstrange pentaquarks are stable against strong decays
SU(3) Clebsch-Gordan coefficients at large
No full textpeer reviewedIt is argued that several papers where SU(3) Clebsch-Gordan coefficients were calculated in order to describe properties of hadronic systems are, up to a phase convention,
particular cases of analytic formulae derived by Hecht in 1965 in the context of nuclear physics. This is valid for irreducible representations with multiplicity one in the corresponding
Clebsch-Gordan series. For multiplicity two, Hecht has proposed an alternative which can provide correct sub-leading orders in large studies
SU(3) flavor symmetry breaking in large excited baryons
No full textpeer reviewedThe expansion method for studying the mass spectrum of excited baryons is shortly reviewed
together with applications to mixed symmetric states.
The multiplet, belonging to the = 2 band,
is reanalyzed, with emphasis on hyperons
and the SU(3) symmetry breaking operators entering the mass formula to first order.
An important result is that the hierarchy of masses as a function of strangeness is
correctly reproduced for all multiplets.
Predictions for unknown excited hyperons to SU(6) O(3) multiplets are made
Relations between strong decay widths of the P_c pentaquarks in the SU(4) flavor-spin model
Get PDFpeer reviewedIn a previous work we have studied the isospin 1/2 lowest positive and negative parity states of the pentaquark , in a constituent quark model with a linear confinement and an SU(4) flavor-spin hyperfine interactionand we compared the results with the , and pentaquarks observed at LHCb in 2019.Here we extend the previous work by calculating ratios of decay rates of the pentaquarks to and
and similarly the ratio of decay rates to and .
Our predictions are based on the SU(4)SU(2) structure of compact pentaquarks
Excited hyperons of the N = 2 band in the 1/Nc expansion
No full textThe spectrum of excited baryons in the = 2 band is reanalyzed
in the expansion method, with emphasis on hyperons.
Predictions are made for the classification of these excited baryons into SU(3) singlets, octets and decuplets
On the existence of heavy tetraquarks
Get PDFPrevious work done in collaboration with David Brink is reviewed in the light of
the recent observation of new charmonium-like resonances which can be interpreted
as tetraquarks. In the framework of a schematic quark model the spectrum of c¯cq¯q
tetraquarks is presented
The discovery and properties of pentaquarks
Get PDFpeer reviewedThe pentaquarks are exotic baryons formed of four quarks and an antiquarks. Their existence has been discussed in the literature over the last 30 years or more, first in connection with kaon nucleon scattering data. The subject has been revived by the end of 2002 when experimental evidence of a narrow baryon of strangeness S = +1, and mass M similar or equal to 1530 MeV has been found. This is interpreted as the lightest member of an SU(3)-flavor antidecuplet. Here we shall mainly review the predictions of pentaquark properties as e.g. mass, spin and parity, within constituent quark models. Both light and heavy pentaquarks will be presented
Quark model: recent issues
Get PDFIn the first part I briefly survey recent issues in constituent quark models raised by the observation of unusual hadronic states. In particular I discuss the role of higher Fock components in the wave function of baryons and the possible interpretation of open charm and of new charmonium-type resonances as tetraquarks. In the second part I show support for the quark
model dynamics obtained in a model independent way from the 1/Nc expansion approach of QCD which proved to be successful in describing baryon properties
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