Abstract
We use a constituent model to analyze the stability of pentaquark Q¯qqqq configurations with a heavy antiquark c¯ or b¯, and four light quarks uuds, ddsu or ssud. The interplay between chromoelectric and chromomagnetic effects is not favorable, and, as a consequence, no bound state is found below the lowest dissociation threshold.
Highlights
There is a renewed interest in the spectroscopy of exotic hadrons containing one or two heavy constituents
II, we present briefly the model and the variational method
A calculation of the masses of mesons D(cu), . . . , Bs(sb) and baryons p(uud), . . . Λb(bud) leads to the threshold masses shown in Table I, which displays the best 5-body energy with the required convergence, N = 5 or N = 6 in Eq (4)
Summary
There is a renewed interest in the spectroscopy of exotic hadrons containing one or two heavy constituents. An eigenvalue O4 = 16 is found for a qqqq system in a state of color 3 and spin Jq = 0 corresponding to a SU(3)F triplet of flavor This means that in the limit where the mass of the heavy quark becomes infinite, i.e., the chromomagnetic energy is restricted to the light sector, a downwards shift δM = 8 a ∼ 150 MeV is obtained for Qqqqq, as compared to its lowest threshold Qq + qqq. In this letter we adopt a generic constituent model, containing chromoelectric and chromomagnetic contributions, tuned to reproduce the masses of the mesons and baryons entering the various thresholds and study the pentaquark configurations Quuds, Qddsu and Qssdu with Q = c or b, for both s = 1/2 and s = 3/2, using a powerful variational method. If a variational state converges to a bound state as N increases, it includes sizable hidden-color components even for low N
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