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Albaladejo, M., Guo, F. K., Hanhart, C., Meissner, U. G., Nieves, J., Nogga, A., et al. (2017). Note on X(3872) production at hadron colliders and its molecular structure. Chin. Phys. C, 41(12), 121001–3pp.
Abstract: The production of the X (3872) as a hadronic molecule in hadron colliders is clarified. We show that the conclusion of Bignamini et al., Phys. Rev. Lett. 103 (2009) 162001, that the production of the X(3872) at high pT implies a non-molecular structure, does not hold. In particular, using the well understood properties of the deuteron wave function as an example, we identify the relevant scales in the production process.
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Ji, T., Dong, X. K., Albaladejo, M., Du, M. L., Guo, F. K., Nieves, J., et al. (2023). Understanding the 0(++) and 2(++) charmonium(-like) states near 3.9 GeV. Sci. Bull., 68(7), 688–697.
Abstract: We propose that the X(3915) observed in the J/psi x channel is the same state as the chi(c2)(3930), and the X(3960), observed in the Ds+Ds- channel, is an S-wave Ds+Ds- hadronic molecule. In addition, the J(PC) = 0(++) component in the B+ -> D+D-K+ assigned to the X(3915) in the current Review of Particle Physics has the same origin as the X(3960), which has a mass around 3.94 GeV. To check the proposal, the available data in the D (D) over bar and Ds+Ds- channels from both B decays and gamma gamma fusion reaction are analyzed considering both the D (D) over bar -D-s(D) over bar (s)-D*(D) over bar*-D-s*(D) over bar (s)* coupled channels with 0(++) and a 2(++) state introduced additionally. It is found that all the data in different processes can be simultaneously well reproduced, and the coupled-channel dynamics produce four hidden-charm scalar molecular states with masses around 3.73, 3.94, 3.99 and 4.23 GeV, respectively. The results may deepen our understanding of the spectrum of charmonia as well as of the interactions between charmed hadrons.
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Albaladejo, M., Nieves, J., & Tolos, L. (2021). D(D)over-bar* scattering and chi(c1) (3872) in nuclear matter. Phys. Rev. C, 104(3), 035203–20pp.
Abstract: We study the behavior of the chi(c1) (3872), also known as X(3872), in dense nuclear matter. We begin from a picture in vacuum of the X(3872) as a purely molecular (D (D) over bar*-c.c.) state, generated as a bound state from a heavy-quark symmetry leading-order interaction between the charmed mesons, and analyze the D (D) over bar* scattering T matrix (T-D (D) over bar*) inside of the medium. Next, we consider also mixed-molecular scenarios and, in all cases, we determine the corresponding X(3872) spectral function and the D (D) over bar* amplitude, with the mesons embedded in the dense environment. We find important nuclear corrections for T-D (D) over bar* and the pole position of the resonance, and discuss the dependence of these results on the D (D) over bar* molecular component in the X(3872) wave function. These predictions could be tested in the finite-density regime that can be accessed in the future CBM and PANDA experiments at the Facility for Antiproton and Ion Research (FAIR).
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Montesinos, V., Albaladejo, M., Nieves, J., & Tolos, L. (2023). Properties of the Tcc(3875)+ and Tcbar,cbar(3875)- and their heavy-quark spin partners in nuclear matter. Phys. Rev. C, 108(3), 035205–15pp.
Abstract: We discuss the modification of the properties of the tetraquark-like Tcc(3875)+ and Tc over bar c over bar (3875)- states in dense nuclear matter. We consider the Tcc+ and Tc over bar c over bar – in vacuum as purely isoscalar D*D and D*D S-wave bound states, respectively, dynamically generated from a heavy-quark effective interaction between the charmed mesons. We compute the D, D, D*, and D* spectral functions embedded in a nuclear medium and use them to determine the corresponding Tcc+ and Tc over bar c over bar – self-energies and spectral functions. We find important modifications of the D*D and D*D scattering amplitudes and of the pole position of these exotic states already for p0/2, with p0 the normal nuclear density. We also discuss the dependence of these results on the D*D (D*D) molecular component in the Tcc+ (Tc over bar c- over bar ) wave function. Owing to the different nature of the D(*)N and D(*)N interactions, we find characteristic changes of the in-medium properties of the Tcc(3875)+ and Tc over bar c over bar (3875)-, which become increasingly visible as the density increases. The experimental confirmation of the found distinctive density pattern will give support to the existence of molecular components in these tetraquark-like states, since in the case they were mostly colorless compact quark structures (cct over bar t over bar and c over bar c over bar tt, with t = u, d), the density behaviors of the Tcc(3875)+ and Tc over bar c over bar (3875)- nuclear medium spectral functions, though different, would not likely be the same as those found in this work for molecular scenarios. Finally, we perform similar analyses for the isoscalar JP = 1+ heavy-quark spin symmetry partners of the Tcc+ (T cc *+ ) and the T c over bar c- over bar (T*- c over bar c over bar ) by considering the D*0D*+ and D*0D*- scattering T matrices.
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Du, M. L., Albaladejo, M., Fernandez-Soler, P., Guo, F. K., Hanhart, C., Meissner, U. G., et al. (2018). Towards a new paradigm for heavy-light meson spectroscopy. Phys. Rev. D, 98(9), 094018–8pp.
Abstract: Since 2003 many new hadrons, including the lowest-lying positive-parity charm-strange mesons D*(s0) (2317) and D-s1 (2460), have been observed that do not conform with quark-model expectations. It was recently demonstrated that various puzzles in the charm-meson spectrum find a natural resolution if the SU(3) multiplets for the lightest scalar and axial-vector states, among them the D*(s0) (2317) and the D-s1 (2460), owe their existence to the nonperturbative dynamics of Goldstone-boson scattering off D-(s) and D*((s)) mesons. Most importantly the ordering of the lightest strange and nonstrange scalars becomes natural. We demonstrate for the first time that this mechanism is strongly supported by the recent high quality data on the B- -> D+ pi(-)pi(-) provided by the LHCb experiment. This implies that the lowest quark-model positive-parity charm mesons, together with their bottom counterparts, if realized in nature, do not form the ground-state multiplet. This is similar to the pattern that has been established for the scalar mesons made from light up, down, and strange quarks, where the lowest multiplet is considered to be made of states not described by the quark model. In a broader view, the hadron spectrum must be viewed as more than a collection of quark-model states.
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