We show that the QCD van der Waals attractive potential is strong enough to bind a φ meson onto a nucleon inside a nucleus to form a bound state. The direct experimental signature for such an exotic state is proposed in the case of subthreshold φ meson photoproduction from nuclear targets. The production rate is estimated and such an experiment is found to be feasible at the Jefferson Laboratory. 25.20.-x, 24.85.+p It has been suggested [1] that the QCD van der Waals interaction, mediated by multi-gluon exchanges, is dominant when the interacting two color singlet hadrons have no common quarks. In fact, the QCD van der Waals interaction is ehanced at low velocity as has been shown by Luke, Manohar, and Savage [2]. This finding supports the prediction that a nuclear-bound quarkonium can be produced in charm production reactions at threshold, and the interpretation that the structures seen in s 10 dσ/dt(pp → pp) and the A N N spin correlation at √ s ∼ 5 GeV and large cm angles [3] can be attributed to ccuuduud resonant states [4]. If these interpretations are correct, then analogous effects could also be expected at the strangeness threshold. The objective of this work is to explore this possibility.We are motivated by the investigation of the nuclearbound quarkonium by Brodsky, Schmidt, and de Téramond [1]. They used a non-relativistic Yukawa type attractive potential V (QQ)A = −αe −µr /r characterizing the QCD van der Waals interaction. They determined the α and µ constants using the phenomenological model of high-energy Pomeron interactions developed by Donnachie and Landshoff [5]. Using a variational wave function Ψ(r) = (γ 3 /π) 1/2 e −γr , they predicted bound states of η c with 3 He and heavier nuclei. Their prediction was confirmed by Wasson [6] using a more realistic V (QQ)A potential taking into account the nucleon distribution inside the nucleus.Similarly, one expects the attractive QCD van der Waals force dominates the φ-N interaction since the φ meson is almost a pure ss state. It is possible that a φ-N bound state or resonant state can be formed in some reactions. In photoproduction of φ meson from a proton target above threshold, the formation of a bound φ-N state is not likely because of the momentum mismatch between the φ and the recoil proton. As such, no experimental evidence exists on the formation of the φ-N bound state up to now. On the other hand, such a φ-N bound state could be formed inside a nucleus. In this paper, we will verify this possibility and make predictions for future experimental tests.Using the variational method and following Ref.[1] to assume V (ss),N = −αe µr /r, we find that a bound state of φ-N is possible with α = 1.25 and µ = 0.6 GeV. The binding energy obtained is 1.8 MeV. Our results should be compared with α = 0.6 and µ = 0.6 GeV determined by Brodsky, Schmidt, and de Téramond [1] for the cc quarkonium. The interaction is expected to be enhanced by (m c /m s ) 3 , i.e., qq separation cubed, from cc to ss. Since the radius of the φ meson is (0.4 fm [7]) twice the ...
Aim: To measure the macular thickness, macular volume and peripapillary retinal nerve fiber layer (RNFL) in healthy Caucasian chil­dren using spectral domain optical coherence tomography (SDOCT) and analyze the correlation of these values with age, refraction, and biometric measurements. Materials and methods: In this cross-sectional study, we recruited 270 healthy children (150 female and 120 male) aged 6 to 17 years with no ocular abnormalities. All children underwent a detailed eye examination. The measurements were obtained using a SDOCT device (SOCT Copernicus REVO). Main outcome measures were macular thickness, macular volume and RNFL thickness. Their correlations with age, refractive error, anterior chamber depth (ACD) and axial length (AL) was analyzed. Right eyes of all subjects were selected for analysis. Results: In this study group (mean age 10.70±2.82 years), the average peripapillary RNFL thickness was 117.11±9.15 μm, the central macular thickness was 232.10±15.81 μm, the average macular thickness was 286.70±9.82 μm, and the average macular volume was 8.01±0.28 mm³. The average values for the biometric data were: axial length – 23.16±0.94 mm, anterior chamber depth – 3.64±0.26 mm, the spherical equivalent (SE) value – +0.81±0.58 diopter. Central macular thickness, inner macular thickness (superior, inferior, nasal, temporal quadrants) values, total macular thickness and macular volume were significantly higher in males than in females. We found a positive correlation between central macular thickness, inner nasal macular thickness, outer inferior macular thickness values, and age. Also, we found a significant correlation between the average macular thickness values and the average macular volume values (p<0.0001). RNFL measurements did not correlate with age (p=0.199). Almost all macular parameters were consistently positively cor­related with SE. A significant correlation was also found between the central macular thickness, inner inferior macular thickness, inner nasal macular thickness and the ACD. We found a significant correlation between the average macular thickness, macular volume, inner superior macular thickness, outer macular thickness (superior, inferior, nasal, temporal quadrants) values and the AL. Conclusion: This study found normal reference ranges for RNFL and macular parameters measured by SOCT Copernicus REVO in healthy Caucasian children aged 6-17 years. This normative values could be very useful in early diagnosing and monitoring of optic neuropathy, glaucoma and macular diseases in childhood.
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