|
Richard, J. M., Valcarce, A., & Vijande, J. (2021). Effect of relativistic kinematics on the stability of multiquarks. Phys. Rev. D, 103(5), 054020–8pp.
Abstract: We discuss whether the bound nature of multiquark states in quark models could benefit from relativistic effects on the kinetic energy operator. For mesons and baryons, relativistic corrections to the kinetic energy lead to lower energies, and thus call for a retuning of the parameters of the model. For multiquark states, as well as their respective thresholds, a comparison is made of the results obtained with nonrelativistic and relativistic kinetic energy. It is found that the binding energy is lower in the relativistic case. In particular, QQ (q) over bar(q) over bar tetraquarks with double heavy flavor become stable for a larger ratio of the heavy to light quark masses; the all-heavy tetraquarks QQ (Q) over bar(Q) over bar that are not stable in standard nonrelativistic quark models remain unstable when a relativistic form of kinetic energy is adopted.
|
|
|
Richard, J. M., Valcarce, A., & Vijande, J. (2020). Very Heavy Flavored Dibaryons. Phys. Rev. Lett., 124(21), 212001–4pp.
Abstract: We explore the possibility of very heavy dibaryons with three charm quarks and three beauty quarks, bbbccc, using a constituent model which should lead to the correct solution in the limit of hadrons made of heavy quarks. The six-body problem is treated rigorously, in particular taking into account the orbital, color, and spin mixed-symmetry components of the wave function. Unlike a recent claim based on lattice QCD, no bound state is found below the lowest dissociation threshold.
|
|
|
Garcilazo, H., Valcarce, A., & Vijande, J. (2020). Neutral baryonic systems with strangeness. Int. J. Mod. Phys. E, 29(1), 1930009–22pp.
Abstract: We review the status as regards to the existence of three- and four-body bound states made of neutrons and Lambda hyperons. For interesting cases, the coupling to neutral baryonic systems made of charged particles of different strangeness has been addressed. There are strong arguments showing that the Lambda nn system has no bound states. Lambda Lambda nn strong stable states are not favored by our current knowledge of the strangeness -1 and -2 baryon-baryon interactions. However, a possible Xi(-) t quasibound state decaying to Lambda Lambda nn might exist in nature. Similarly, there is a broad agreement about the nonexistence of Lambda Lambda n bound states. However, the coupling to Xi NN states opens the door to a resonance above the Lambda Lambda n threshold.
|
|
|
Garcilazo, H., Valcarce, A., & Vijande, J. (2020). Xi(-)t quasibound state instead of Lambda Lambda nn bound state. Chin. Phys. C, 44(2), 024102–7pp.
Abstract: The coupled Lambda Lambda nn – Xi-pnn system was studied to investigate whether the inclusion of channel coupling is able to bind the Lambda Lambda nn system. We use a separable potential three-body model of the coupled Lambda Lambda nn – Xi-pnn system and a variational four-body calculation with realistic interactions. Our results exclude the possibility of a bound state by a large margin. Instead, we found a Xi(-)t quasibound state above the Lambda Lambda nn threshold.
|
|
|
Hernandez, E., Vijande, J., Valcarce, A., & Richard, J. M. (2020). Spectroscopy, lifetime and decay modes of the T-bb(-) tetraquark. Phys. Lett. B, 800, 135073–9pp.
Abstract: We present the first full-fledged study of the flavor-exotic isoscalar T-bb(-) equivalent to bb (u) over bar(d) over bar tetraquark with spin and parity J(P) = 1(+). We report accurate solutions of the four-body problem in a quark model, characterizing the structure of the state as a function of the ratio M-Q/m(q) of the heavy to light quark masses. For such a standard constituent model, T-bb(-) lies approximately 150 MeV below the strong decay threshold B- (B) over bar*(0) and 105 MeV below the electromagnetic decay threshold B- (B) over bar (0)gamma. We evaluate the lifetime of T-bb(-), identifying the promising decay modes where the tetraquark might be looked for in future experiments. Its total decay width is Gamma approximate to 87 x 10(-15) GeV and therefore its lifetime tau approximate to 7.6 ps. The promising final states are B*(-) D*(+) l (v) over bar (l) and (B) over bar*(0) l (v) over bar (l) among the semileptonic decays, and B*(-) D*(+) D-s*(-), (B) over bar*(0) D*(0) D-s*(-), and B*(-) D*(+) rho(-) among the nonleptonic ones. The semileptonic decay to the isoscalar J(P) = 0(+) tetraquark T-bc(0) is also relevant but it is not found to be dominant. There is a broad consensus about the existence of this tetraquark, and its detection will validate our understanding of the low-energy realizations of Quantum Chromodynamics (QCD) in the multiquark sector.
|
|