1,027 research outputs found
The discovery and properties of pentaquarks
The 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 = + 1, and mass 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.Comment: Plenary talk, MESON2004 Conference Proceedings, Crakow, June 4-8 200
Mass formula for strange baryons in large QCD versus quark model
A previous work establishing a connection between a quark model, with
relativistic kinematics and a -confinement plus one gluon exchange, and the
expansion mass formula is extended to strange baryons. Both methods
predict values for the SU(3)-breaking mass terms which are in good agreement
with each other. Strange and nonstrange baryons are shown to exhibit Regge
trajectories with an equal slope, but with an intercept depending on the
strangeness. Both approaches agree on the value of the slope and of the
intercept and on the existence of a single good quantum number labeling the
baryons within a given Regge trajectory.Comment: 2 figure
On a three-body confinement force in hadron spectroscopy
Recently it has been argued that a three-body colour confinement interaction
can affect the stability condition of a three-quark system and the spectrum of
a tetraquark described by any constituent quark model. Here we discuss the role
of a three-body colour confinement interaction in a simple quark model and
present some of its implications for the spectra of baryons, tetraquarks and
six-quark systems.Comment: 19 pages (RevTeX), addition of new material regarding the NN
interaction, more accurate discussion of the baryonic case, accepted for
publication in Phys. Rev.
The 4th International Conference on Social Responsibility, Ethics, and Sustainable Business. Athens, Greece, October 8 & 9, 2015
New Baryons in the Delta eta and Delta omega Channels
The decays of excited nonstrange baryons into the final states Delta eta and
Delta omega are examined in a relativized quark pair creation model. The
wavefunctions and parameters of the model are fixed by previous calculations of
N pi and N pi pi, etc., decays through various quasi-two body channels
including N eta and N omega. Our results show that the combination of
thresholds just below the region of interest and the isospin selectivity of
these channels should allow the discovery of several new baryons in such
experiments.Comment: 10 pages, RevTe
Food security and migration in Africa: A validation of theoretical links using case studies from literature
The connection between food security and migration is increasingly discussed by both international agencies and academic literature. However, despite several improvements, we continue to know little about the complex causal-effect relations that link these aspects and, in particular, how much migration patterns are affected by food security issues and how much, as a feedback, migration can affect food security, on both the origin and destination areas. This paper aims firstly to draw a general framework of this nexus and then to validate it using empirical literature on the African continent. A few common points can be emphasized for the continent: due to structural and familiar characteristics, different strategies based on opportunity costs or risk minimization (including food security aspects) may emerge; individuals often migrate following household strategies; multi-nodal households are emerging; land grabbing and land tenure security represent important drivers to be considered; emergencies or critical situations often cause the erosion of women rights. In many situations, the poverty trap prevents most food insecure households to leave marginal lands
Pentaquarks in string dynamics
The masses of , , and pentaquarks are
evaluated in a framework of both the Effective Hamiltonian approach to QCD and
spinless Salpeter using the Jaffe-Wilczek diquark approximation and the string
interaction for the diquark-diquark-antiquark system. The masses of the light
pentaquarks are found to be in the region above 2 GeV. The similar calculations
yield the mass of pentaquark 3250 MeV and
pentaquark 6509 MeV.Comment: 5 pages. Based on talk by I.M.Narodetskii at BEACH 2004, 6th
International Conference on Hyperons, Charm and Beauty Hadrons, Illionois
Institute of Technology, Chicago, June. 27 - July 3, 2004. Typos correcte
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