Spin observables and the determination of the parity of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>Θ</mml:mi><mml:mo>+</mml:mo></mml:msup></mml:math>in photoproduction reaction

Nakayama, K.; Love, W.G.

doi:10.1103/physrevc.70.012201

Cited by 22 publications

(34 citation statements)

References 36 publications

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“…As we have known, other identifications have been also discussed in the literature, for instance, using large N c expansion [35,36,37]. It is therefore important to determine the quantum numbers of Θ + in experiments [38,39,40,41,42,43,44,45,46,47,48,49], not only for the exotic particles but also for the baryon spectroscopy of nonexotic particles. Study of high spin states in phenomenological models and calculations based on QCD are strongly encouraged [31].…”

Section: Summary and Discussionmentioning

confidence: 99%

Phenomenology of spin 3/2 baryons with pentaquarks

Hyodo¹

2005

Phys. Rev. D

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We examine several assignments of spin and parity for the pentaquark Θ + state (J P = 1/2 ± , 3/2 ± ) in connection with known baryon resonances. Assuming that the Θ + belongs to an antidecuplet representation which mixes with an octet, we calculate the mass spectra of the flavor partners of the Θ + based on the SU(3) symmetry. The decay widths of the Θ + and nucleon partners are analyzed for the consistency check of the mixing angle obtained from the masses. It is found that a suitable choice of the mixing angle successfully reproduces the observed masses of Θ(1540) and Ξ 3/2 (1860), when their spin and parity are assigned to be J P = 3/2 − , together with other J P = 3/2 − resonances. The decay widths of Θ → KN , N (1520) → πN , and N (1700) → πN are also reproduced simultaneously.

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Section: Summary and Discussionmentioning

confidence: 99%

Phenomenology of spin 3/2 baryons with pentaquarks

Hyodo¹

2005

Phys. Rev. D

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“…In the photoproduction case, the determination of parity is also possible if we are able to control the polarization of both the initial and the final states [63], which is however very difficult in the present experimental setup.…”

Section: Polarized Proton Beam and Targetmentioning

confidence: 99%

Structure and reactions of pentaquark baryons

Hosaka

2006

Pramana - J Phys

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We review the current status of the exotic pentaquark baryons. After a brief look at experiments of both positive and negative results, we discuss theoretical methods to study the structure and reactions for the pentaquarks. First we introduce the quark model and the chiral soliton model, where we discuss the relation of mass spectrum and parity with some emphasis on the role of chiral symmetry. It is always useful to picture the structure of the pentaquarks in terms of quarks. As for other methods, we discuss a model independent method, and briefly mention the results from the lattice and QCD sum rule. Decay properties are then studied in some detail, which is one of the important properties of Θ + . We investigate the relation between the decay width and the quark structure having certain spin-parity quantum numbers. Through these analyses, we consider as plausible quantum numbers of Θ + , J P = 3/2 − . In the last part of this note, we discuss production reactions of Θ + which provide links between the theoretical models and experimental information. We discuss photoproductions and hadron-induced reactions which are useful to explore the nature of Θ + .

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“…As discussed in Refs. [137][138][139], however, we cannot avoid model-dependence on the spin asymmetries in most reactions, which makes it very hard to study the parity of Θ by the spin asymmetries except some special cases like the NN reaction near the threshold. Therefore, we do not present our results on the spin asymmetries and do not make a definite conclusion on the dependence of spin asymmetries on the parity of Θ.…”

Section: Shown Inmentioning

confidence: 99%

“…[136][137][138][139][140][141][142], where efforts to determine these properties, in particular the parity of the Θ + , in a model-independent way in photo-and hadro-production reactions have been reported.…”

Section: Introductionmentioning

confidence: 99%

Pentaquark Θ+(1540) production in γN→KK¯N reactions

Nakayama

Lee

2006

Physics Reports

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The recent developments in the search of exotic pentaquark hadrons are briefly reviewed. We then focus on investigating how the exotic pentaquark Θ(1540) baryon production can be identified in the γN → KKN reactions, focusing on the influence of the background (non-Θ production) mechanisms. By imposing the SU(3) symmetry and using various quark model predictions, we are able to fix the coupling constants for evaluating the kaon backgrounds, the KK production through the intermediate vector meson and tensor meson photoproduction, and the mechanisms involving intermediate Λ (1116), Λ(1405), Λ(1520), Σ(1193), Σ(1385), and ∆(1232) states. The vector meson photoproduction part is calculated from a phenomenological model which describes well the experimental data at low energies. We point out that the neutral tensor meson production can not be due to π 0 -exchange as done by Dzierba et al. [Phys. Rev. D 69, 051901 (2004)] because of C parity. The neutral tensor meson production is estimated by considering the vector meson exchange and found to be too weak to generate any peak at the position near Θ(1540). For Θ(1540) production, we assume that it is an isoscalar and hence can only be produced in γn → K + K − n and γp → K 0 K 0 p reactions, but not in γp → K + K − p and γn → K 0 K 0 n. The total cross section data of γp → K + K − p is thus used to fix the form factors which regularize the background amplitudes so that the signal of Θ(1540) in γn → K + K − n and γp → K 0 K 0 p cross sections can be predicted.We find that the predicted K + K − and K + n invariant mass distributions of the γn → K + K − n reaction can qualitatively reproduce the shapes of the JLab data. However, the predicted Θ(1540) peak can not be identified unambiguously with the data. High statistics experiments are needed to resolve the problem. We also find that an even-parity Θ is more likely to be detected, while it will be difficult to identify an odd-parity Θ, even if it exists, from the background continuum, if its coupling constants are small as in the present quark model predictions.

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Spin observables and the determination of the parity ofΘ+in photoproduction reaction

Cited by 22 publications

References 36 publications

Phenomenology of spin 3/2 baryons with pentaquarks

Phenomenology of spin 3/2 baryons with pentaquarks

Structure and reactions of pentaquark baryons

Pentaquark Θ+(1540) production in γN→KK¯N reactions

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