φ-Nbound state

Abstract

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 ...

Possible pentaquarks with heavy quarks

“…This shows that the N J/ψ of J P = scattering process. In fact, the possible existence of a nuclear bound quarkonium state was proposed more than 20 years ago by Brodsky et al [38]; Gao et al [39] also predicted the existence of the N φ bound state, which is very similar to the N J/ψ state; and the recent lattice QCD calculation also supported the existence of the strangenium-nucleus and the charmonium-nucleus bound states [40]. Therefore, searching for the N J/ψ resonance state is interesting work for the future.…”

Near-threshold photoproduction of ϕ mesons from deuterium

“…Similarly, one expects that the attractive QCD van der Waals force also dominates the φ-N interaction. A bound state of φ-N was found to be possible by Gao, Lee, and Marinov [15]. Such a bound state was also predicted by Huang, Zhang, and Yu using a chiral SU(3) quark model and the extended chiral SU(3) quark model by solving the Resonant Group Method (RGM) equation [16].…”

“…Such a bound state was also predicted by Huang, Zhang, and Yu using a chiral SU(3) quark model and the extended chiral SU(3) quark model by solving the Resonant Group Method (RGM) equation [16]. Subthreshold production kinematics have been proposed [15] as advantageous for the search of φ − N bound states from nuclear targets.…”

Photoproduction of bound states with hidden charm

“…Following the previous investigations [7,28], we assume that the interaction between a J/Ψ and a nucleus with mass number A can be parameterized as a non-relativistic potential of the following Yukawa form…”