242 research outputs found
Chiral anomaly and strange-nonstrange mixing
As a first step, a simple and pedagogical recall of the - system
is presented, in which the role of the axial anomaly, related to the
heterochiral nature of the multiplet of (pseudo)scalar states, is underlined.
As a consequence, is close to the octet and to the singlet
configuration. On the contrary, for vector and tensor states, which belong to
homochiral multiplets, no anomalous contribution to masses and mixing is
present. Then, the isoscalar physical states are to a very good approximation
nonstrange and strange, respectively. Finally, for pseudotensor states, which
are part of an heterochiral multiplet (just as pseudoscalar ones), a sizable
anomalous term is expected: roughly corresponds to the octet
and to the singlet.Comment: 4 pages. Prepared for the proceedings of MESON 2018, 15th
International Workshop on Meson Physics, KRAK\'OW, POLAND, 7th - 12th June
201
Modelling glueballs
Glueballs are predicted in various theoretical approaches of QCD (most
notably lattice QCD), but their experimental verification is still missing. In
the low-energy sector some promising candidate for the scalar glueball exist,
and some (less clear) candidates for the tensor and pseudoscalar glueballs were
also proposed. Yet, for heavier gluonic states there is much work to be done
both from the experimental and theoretical points of view. In these
proceedings, we briefly review the current status of research of glueballs and
discuss future developments.Comment: Proceedings of MESON2016, 14th International Workshop on Meson
Production, Properties and Interaction KRAK\'OW, POLAND, 2-7/6/2016. 6 page
Revisiting the axial anomaly for light mesons and baryons
The axial anomaly is responsible for the masses and mixing of the mesons
and . An open question is if (and to what extent) it affects also
other hadrons. We show that anomalous terms can be important to understand the
spectroscopy of the pseudotensor mesons and . In
fact, pseudotensor mesons belong to a so-called heterochiral multiplet, for
which a quadratic mixing term between nonstrange and strange isoscalar members
arises. On the contrary, for so-called homochiral multiplets, such as the
ground-state (axial-)vector and tensor mesons, this mixing is not possible,
hence one can easily understand why the isoscalar members of these multiplets
are almost purely nonstrange and strange, respectively. Moreover, the axial
anomaly can be also coupled to baryons (within the mirror assignment), and thus
it helps to explain the large decay width
and to clarify which baryons are chiral partners.Comment: 6 pages. Prepared for the proceedings of the XVII International
Conference on Hadron Spectroscopy and Structure - Hadron2017, 25-29
September, 2017, University of Salamanca, Salamanca, Spai
f_{2}(1270),a_{1}(1260)f_{0}(1370)$ as dynamically reconstructed quark-antiquark states
It is explained why the interpretation of the resonances
and as quark-antiquark states is legitimate. The
result of the quark model and of recently performed Bethe-Salpeter studies are
not (necessarily) in conflict and can be understood as two different approaches
toward the description of the same quark-antiquark resonances.Comment: 8 pages, 2 figures. Based on the contribution given at the Chiral10
Workshop, Valencia (Spain), June 21-24, 201
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