scholarly journals Beam asymmetries from light scalar meson photoproduction on the proton at GlueX

2020 ◽  
Author(s):  
Keyword(s):  
Scalar Meson ◽  
Meson Photoproduction ◽  
Beam Asymmetries ◽  
Light Scalar

scholarly journals Beam Asymmetries from Light Scalar Meson Production on the Proton at GlueX

2020 ◽  
Vol 1643 (1) ◽  
pp. 012169
Author(s):  
Stuart Fegan
Keyword(s):  
Scalar Meson ◽  
Meson Production ◽  
Real Photon ◽  
Final States ◽  
Ongoing Research ◽  
Beam Asymmetry ◽  
Strong Force ◽  
Beam Asymmetries ◽  
Light Scalar ◽  
Large Acceptance

Abstract The GlueX facility, featuring a linearly polarised 9 GeV real photon beam delivered to a large-acceptance detector system, has recently completed its first phase of running, and analysis efforts of this dataset are well underway. It has been suggested that at GlueX energies, quark systems beyond the three quark and quark-antiquark systems of baryons and mesons, such as hybrid mesons, tetraquarks and glueballs, should exist, and studies of these systems could shed new light on how quarks combine under the strong force, particularly the role played by gluons. Meticulous study of the spectrum of hadronic states is required to understand the strong force in the non-perturbative energy regime, and the light scalar meson sector is an area that remains poorly understood. GlueX data encompasses final states at energies where photoproduction of the a0 (980) and f 0 (980) mesons can provide discriminatory evidence between various models, manifested in experimental observables such as the cross section and beam asymmetry, and performing detailed measurements of these quantities is considered a priority of the ongoing research program. The work presented showcases efforts to measure the beam asymmetry of the reaction γp→pηπ whose mass spectrum encompasses several mesons, including the a 0(980) light scalar, and the a 2(1320) tensor. Future prospects for related analyses in the light scalar meson sector, informed by this measurement, will also be discussed.

scholarly journals Four-Quark States from Functional Methods

2020 ◽  
Vol 61 (4) ◽  
Author(s):  
Gernot Eichmann ◽  
Christian S. Fischer ◽  
Walter Heupel ◽  
Nico Santowsky ◽  
Paul C. Wallbott
Keyword(s):  
Symmetry Breaking ◽  
Scalar Meson ◽  
Chiral Symmetry Breaking ◽  
The Other ◽  
Feature Article ◽  
Exotic Mesons ◽  
Scalar Mesons ◽  
Functional Methods ◽  
Internal Structures ◽  
Light Scalar

AbstractIn this feature article we summarise and highlight aspects of the treatment of four-quark states with functional methods. Model approaches to those exotic mesons almost inevitably have to assume certain internal structures, e.g. by grouping quarks and antiquarks into (anti-)diquark clusters or heavy-light $$q{\bar{q}}$$ q q ¯ pairs. Functional methods using Dyson–Schwinger and Bethe–Salpeter equations can be formulated without such prejudice and therefore have the potential to put these assumptions to test and discriminate between such models. So far, functional methods have been used to study the light scalar-meson sector and the heavy-light sector with a pair of charmed and a pair of light quarks in different quantum number channels. For all these states, the dominant components in terms of internal two-body clustering have been identified. It turns out that chiral symmetry breaking plays an important role for the dominant clusters in the light meson sector (in particular for the scalar mesons) and that this property is carried over to the heavy-light sector. Diquark-antidiquark components, on the other hand, turn out to be almost negligible for most states with the exception of open-charm heavy-light exotics.

Neutral weak currents and a light scalar meson

1974 ◽  
Vol 10 (7) ◽  
pp. 2313-2315 ◽  
Author(s):  
Saul Barshay
Keyword(s):  
Scalar Meson ◽  
Light Scalar

scholarly journals Inverse mass hierarchy of light scalar mesons driven by anomaly-induced flavor breaking

2020 ◽  
Vol 2020 (5) ◽  
Author(s):  
Yoshiki Kuroda ◽  
Masayasu Harada ◽  
Shinya Matsuzaki ◽  
Daisuke Jido
Keyword(s):  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Scalar Meson ◽  
Chiral Symmetry Breaking ◽  
Linear Sigma Model ◽  
Mass Hierarchy ◽  
Scalar Mesons ◽  
Light Scalar ◽  
Symmetry Breaking Term ◽  
Breaking Term

Abstract We propose a novel mechanism to reproduce the observed mass hierarchy for scalar mesons lighter than 1 GeV (called the inverse hierarchy), regarding them as mesons made of a quark and an anti-quark ($q\bar{q}$ mesons). The source is provided by the SU(3) flavor-symmetry breaking induced by the U(1) axial anomaly. In particular, the anomaly term including the explicit chiral symmetry breaking plays a significant role in the light scalar meson spectrum. To be concrete, we construct a linear sigma model for scalar mesons of $q\bar{q}$ type together with their pseudoscalar chiral partners, including an anomaly-induced explicit chiral symmetry-breaking term. We find that, due to the proposed mechanism, the inverse hierarchy, i.e., $m\left[ a_0 (980) \right] \simeq m\left[ f_0 (980) \right] > m \left[ K_0^\ast (700) \right] > m \left[ f_0(500) \right]$, is indeed realized. Consequently, the quark content of $f_0 (500)$ is dominated by the isoscalar $\bar uu+ \bar dd$ component, and $f_0 (980)$ by the strange quark bilinear one, $s\bar{s}$.

ISOVECTOR COMPONENTS OF LIGHT SCALAR MESON AND NUCLEAR MATTER PROPERTIES

2007 ◽  
Vol 16 (09) ◽  
pp. 2867-2871 ◽  
Author(s):  
C. A. Z. VASCONCELLOS ◽  
E. LÜTZ ◽  
M. RAZEIRA ◽  
B. E. J. BODMANN ◽  
M. DILLIG ◽  
...  
Keyword(s):  
Nuclear Matter ◽  
Scalar Meson ◽  
Mean Field ◽  
Symmetry Transformation ◽  
Hadronic Matter ◽  
Meson Field ◽  
Field Approach ◽  
Relativistic Mean Field ◽  
Light Scalar ◽  
Scalar Meson Field

We have predicted (contribution to this issue) an isovector component of the light scalar meson sector by using the chiral symmetry transformation formalism. On the basis of this result, we study dense hadronic matter in a generalized relativistic mean field approach with σ, ω and ρ mesons as well as nonlinear self-couplings of the I = 1 component of a light scalar meson field and compare its predictions for neutron star properties with results from different models for nuclear matter found in the literature.

scholarly journals Two-body charmed B(s) decays involving a light scalar meson

2017 ◽  
Vol 95 (1) ◽  
Author(s):  
Zhi-Tian Zou ◽  
Ying Li ◽  
Xin Liu
Keyword(s):  
Scalar Meson ◽  
Light Scalar
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