52,398 research outputs found
Can Y(4140) be a tetraquark ?
In this exploratory study the spectrum of tetraquarks of type is calculated within a simple quark model with chromomagnetic
interaction and effective quark masses extracted from meson and baryon spectra.
It is tempting to see if this spectrum can accommodate the resonance Y(4140),
observed by the CDF collaboration, but not yet confirmed. The results seem to
favour the J = 1 sector where the coupling to the VV channel is
nearly as small as that of X(3872), when described as a
tetraquark. This suggests that Y(4140) could possibly be the strange partner of
X(3872), in a tetraquark interpretation. However the sector J = 0
cannot entirely be excluded. This work questions the practice of extracting
effective quark masses containing spin independent contributions, from mesons
and baryons, to be used in multiquark systems as well.Comment: new additional parts, published versio
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Jazz in British new wave cinema - An interview with Sir John Dankworth
Sir John Dankworth, the eminent English composer, conductor, bandleader and jazz musician has written in many genres, including composing over 20 film scores. Of these, Saturday Night and Sunday Morning (1960), The Criminal (1960), The Servant (1963) and Darling (1965) in particular, played a major role in bringing about a new sound in British film during the 1960s. This interview explores Sir John Dankworth's contribution to this innovative Film genre through his jazz-influenced musical scores
Quark model: recent issues
In 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 expansion approach of QCD
which proved to be successful in describing baryon properties.Comment: 10 pages, invited talk at MENU2007, September 10-14, 2007, Juelich,
German
Positive parity pentaquarks in a Goldstone boson exchange model
We study the stability of the pentaquarks uuddQbar, uudsQbar and udssQbar (Q
= c, b, or t) 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.Comment: 13 pages, RevTe
Multiquark states in a Goldstone boson exchange model
We discuss the stability of multiquark systems containing heavy flavours. We
show that the Goldstone boson exchange (GBE) model gives results at variance
with the one-gluon-exchange (OGE) model, i.e. when the GBE model stabilizes a
system the OGE model destabilizes it and vice-versa.Comment: 7 pages, RevTeX, Talk given at Joint ECT*/TJNAF workshop on N*
physics and non-perturbative QCD, May 18-29, 1998, ECT*, Trento, Italy, to be
published in Few-Body Systems Supp
Stability of pentaquarks with a two- plus three-body chromoelectric interaction
We study the stability of pentaquarks within a schematic model based on SU(3)
color symmetry, by taking into account algebraic arguments leading to a
chromoelectric interaction containing two- and three-body parts. It has already
been proven that such an interaction can influence the spectrum of ordinary
baryons and the stability of tetraquarks and hexaquarks.Comment: 11 pages, 1 figure, it matches the published versio
Exploring the spectrum of the hidden charm strange pentaquark in an SU(4) flavor-spin model
We study the spectrum of the isoscalar pentaquark , of
either positive or negative parity, in a constituent quark model with linear
confinement and a flavor-spin hyperfine interaction previously extended to
SU(4) and used to describe the spectrum of the pentaquarks
observed at LHCb in 2019. For positive parity we make a distinction between the
case where one unit of angular momentum is located in the subsystem of four
quarks and the case where the angular momentum is located in the relative
motion between a ground state four-quark subsystem and the antiquark. The
novelty is that we introduce the coupling between different flavor states, due
to the breaking of exact SU(4)-flavor symmetry of the Hamiltonian model, both
for positive and negative parity states. An important consequence is that the
lowest state, located at 4404 MeV, has quantum numbers = while
without coupling the lowest state has = or .Comment: 26 pages, title slightly changed, other minor changes, it matches the
published version. arXiv admin note: text overlap with arXiv:1902.0710
Dynamics of pentaquarks in constituent quark models: recent developments
Some recent developments in the study of light and heavy pentaquarks are
reviewed, mainly within constituent quark models. Emphasis is made on results
obtained in the flavor-spin model where a nearly ideal octet-antidecuplet
mixing is obtained. The charmed antisextet is reviewed in the context of an
SU(4) classification.Comment: Based on talks given at the "Workshop Three days of Hadronic
Physics", Joint Meeting Heidelberg-Liege-Paris-Rostock, December 16-18, 2004,
Spa, Belgium and the International Workshop "Exotic Hadrons", February 21-24,
2005, ECT* Trento, Italy, 9 pages, 1 figure, submitted to AIP Conf. Pro
Structure of light and heavy pentaquarks
Light and heavy pentaquarks are described within a constituent quark model
based on a spin-flavor hyperfine interaction. In this model the lowest state
acquires positive parity. The masses of the light antidecuplet members are
calculated dynamically using a variational method. It is shown that the octet
and antidecuplet states with the same quantum numbers mix ideally due to
SU(3) breaking. Masses of the charmed antisextet pentaquarks are predicted
within the same model.Comment: 6 pages, 2 figures, Plenary talk at the 10th International Symposium
on Meson-Nucleon Physics and the Structure of the Nucleon (MENU04), Beijing,
August 29 - September 4, 2004, reference adde
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