Light scalar mesons in QCD

Narison, Stéphan

doi:10.1016/j.nuclphysbps.2008.12.069

Cited by 37 publications

(30 citation statements)

References 92 publications

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“…see Refs. [1][2][3][4] and references therein.Among the low-lying scalar mesons, the lightest scalar f 0 (600) or σ attracts a lot of interests. It is widely believed that f 0 (600) is like the Higgs boson which plays a crucial role in the spontaneous chiral symmetry breaking.…”

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confidence: 99%

Low-lying scalars in an extended linearσmodel

2012

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We formulate an extended linear σ model of a quarkonia nonet and a tetraquark nonet as well as a complex iso-singlet (glueball) by virtue of chiral symmetry SUL(3) × SUR(3) and UA(1) symmetry. In the linear realization formalism, we study the mass spectra and components of the low-lying scalars and pseudo scalars in this model. The mass matrices for physical staes are obtained and the glueball candidates are examined. We find that the model can accommodate the mass spectra of low-lying states quite well. Our fits indicate that the most glueball like scalar should be 2 GeV or higher while the glueball pseudoscalar is η(1756). We also examine the parameter region where the lightest iso-scalar f0(600) can be the glueball and quarkonia dominant but find such a parameter region may be confronted with the problem of the unbounded vacuum from below.PACS numbers: I. INTRODUCTIONThe pseudoscalar, vector and axial-vector as well as tensor mesons of light quarks have been well-understood in the naive quark model in terms of the chiral symmetry. Despite of its success, the naive quark model can not explain the scalar meson sector, which have the same quantum numbers as the vacuum. There are about 19 states which are twice more than the expectedqq nonet as in vector and tensor sectors, while the mass and decay pattern of these low-lying scalars are different from the expectation of the naive quark model. To understand the nature of these scalars has been the focus of recent studies e.g. see Refs. [1][2][3][4] and references therein.Among the low-lying scalar mesons, the lightest scalar f 0 (600) or σ attracts a lot of interests. It is widely believed that f 0 (600) is like the Higgs boson which plays a crucial role in the spontaneous chiral symmetry breaking. Confirmation of existence of the elusive f 0 (600) from ππ scattering processes settles down a controversy last for more than a few decades [2,5]. The πK scattering [6] and analysis from D decay D + → K − π + π − [7] revealed that κ should also exist. BES II also found such a κ like structure in J/Ψ decays [8]. Combined with the well determined sharp resonances, i.e. isoscalar f 0 (980) and isotriplet a(980) from ππ and πη as well as KK scattering processes, now it is accepted in literature that these low-lying scalar mesons (say less than 1 GeV) can be cast into a chiral nonet. The next important issue is what is the nature of this nonet.There are a couple of viewpoints on the nature of this nonet. For example,the tetraquark model [9] can explain the mass hierarchy and decay pattern of this nonet quite successfully and is further supported from other experimental data, like the photon-photon collision data, which prefer the tetraquark interpretation for the lowest scalar meson nonet [10] (where it is demonstrated that f 0 (980) should be a tetraquark dominant state with great details). An alternative interpretation is that this nonet is bound state of the meson-meson molecule [11]. In any way, this nonet challenges a self-consistent interpretation in the naive quark mod...

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confidence: 99%

Low-lying scalars in an extended linearσmodel

2012

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“…For example in quenched lattice approximation the mass of the lowest scalar glueball was calculated to be M 0+ = 1.550 GeV [16], M 0+ = 1.730 GeV [17] or M 0+ = 1.709 GeV in [18] (see [19] for a thorough review). In the QCD sum rules approach, the lowest scalar glueballs are predicted to be [29]- [31] M 0 + = 0.9 − 1.1 GeV and M ′ 0 + = 1.5 − 1. 6 GeV with the possibility of a broad lower state M 0+ = 0.7 GeV ( [29,31]).…”

Section: Introductionmentioning

confidence: 99%

“…In the QCD sum rules approach, the lowest scalar glueballs are predicted to be [29]- [31] M 0 + = 0.9 − 1.1 GeV and M ′ 0 + = 1.5 − 1. 6 GeV with the possibility of a broad lower state M 0+ = 0.7 GeV ( [29,31]). However, experiment has not yet detected "pure" scalar (or pseudoscalar) glueballs, because, expectedly, these composites mix with the appropriate quark building blocks of mesons and thereby "hide" inside some of the known mesonic states such as several of the isosinglet scalar states in the 1-2 GeV range [f 0 (1370), f 0 (1500) and f 0 (1710)] which are considered to have noticeable glue admixtures.…”

Section: Introductionmentioning

confidence: 99%

Generalized linear sigma model with two glueballs

Fariborz

Jora

2018

Phys. Rev. D

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We present a generalized linear sigma model that includes both scalar and pseudoscalar glueballs in addition to a quark-antiquark as well as a four-quark chiral nonet. Utilizing the axial and trace anomalies of QCD (at the effective mesonic level), we aim to develope the most general structure of the Lagrangian which can be used to study the interaction of quarkonia with glueballs. We then study the effect of scalar glueball on the vacuum of the model by considering a decoupling limit in which the glueball fields are decoupled from quarkonia. This determines the properties of the pure scalar glueball and builds a practical foundation for determining the model parameters when the interactions are turned on.

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“…Light scalar mesons are the subject of extensive theoretical and experimental investigation in recent years (see. [1] and references therein). The structure of these mesons in terms of constituent quarks and gluons in rather vague.…”

Section: Introductionmentioning

confidence: 99%

Scalar mesons in the decays η′ → 3π 0 and η′ → π 0 π + π −

2010

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The decays η ′ → 3π 0 and π 0 π + π − were consider in isobar model approach. Branching ratio and Dalitz-plot shape of the decay η ′ → 3π 0 can be explain by a0-and σ-meson contributions. The σ meson term is needed for the Dalitz-plot distribution reconstruction. The branching ratio of the decay η ′ → π 0 π + π − can be calculated in the same isobar framework. The prediction for the Dalitz-plot of this decay is shown which strongly dependents from model parameters.

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Light scalar mesons in QCD

Cited by 37 publications

References 92 publications

Low-lying scalars in an extended linearσmodel

Low-lying scalars in an extended linearσmodel

Generalized linear sigma model with two glueballs

Scalar mesons in the decays η′ → 3π 0 and η′ → π 0 π + π −

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