Abstract
In terms of mass generation in the strong interaction without chiral symmetry breaking, we perform the first study for light scalar-quarks (colored scalar particles with or idealized diquarks) and their color-singlet hadronic states using quenched lattice QCD with (i.e., ) and lattice size . We investigate “scalar-quark mesons” and “scalar-quark baryons” as the bound states of scalar-quarks . We also investigate the color-singlet bound states of scalar-quarks and quarks , i.e., , , and , which we name “chimera hadrons.” All the new-type hadrons including are found to have a large mass even for zero bare scalar-quark mass at . We find a “constituent scalar-quark/quark picture” for both scalar-quark hadrons and chimera hadrons. Namely, the mass of the new-type hadron composed of ’s and ’s, , approximately satisfies , where and are the constituent scalar-quark and quark masses, respectively. We estimate the constituent scalar-quark mass for at as , which is much larger than the constituent quark mass in the chiral limit. Thus, scalar quarks acquire a large mass due to large quantum corrections by gluons in the systems including scalar quarks. Together with other evidences of mass generation of glueballs and charmonia, we conjecture that all colored particles generally acquire a large effective mass due to dressed gluon effects. In addition, the large mass generation of pointlike colored scalar particles indicates that plausible diquarks used in effective hadron models cannot be described as the pointlike particles and should have a much larger size than .
6 More- Received 20 March 2007
DOI:https://doi.org/10.1103/PhysRevD.75.114503
©2007 American Physical Society