On the Existence of Heavy Pentaquarks: The large Nc and Heavy Quark Limits and Beyond

Abstract

We present a very general argument that the analogue of a heavy pentaquark (a state with the quantum numbers of a baryon combined with an additional light quark and a heavy antiquark) must exist as a particle stable under strong interactions in the combined heavy quark and large Nc limits of QCD. Moreover, in the combined limit these heavy pentaquark states fill multiplets of SU(4)xO(8)xSU(2). We explore the question of whether corrections in the combined 1/Nc and 1/mQ expansions are sufficiently small to maintain this qualitative result. Since no model-independent way is known to answer this question, we use a class of ``realistic'' hadronic models in which a pentaquark can be formed via nucleon-heavy meson binding through a pion-exchange potential. These models have the virtue that they necessarily yield the correct behavior in the combined limit, and the long-distance parts of the interactions are model independent. If the long-distance attraction in these models were to predict bound states in a robust way (i.e., largely insensitive to the details of the short-range interaction), then one could safely conclude that heavy pentaquarks do exist. However, in practice the binding does depend very strongly on the details of the short-distance physics, suggesting that the real world is not sufficiently near the combined large Nc, mQ limit to use it as a reliable guide. Whether stable heavy pentaquarks exist remains an open question.

11 pages; references added

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Cited by in corpus (21)

• Heavy Hadrons in Nuclear Matter
• Exotic baryons from a heavy meson and a nucleon -- Negative parity states --
• Exotic nuclei with open heavy flavor mesons
• Hidden-charm pentaquarks as a meson-baryon molecule with coupled channels for ${\bar{D}}^{(\ast )}{\Lambda }_{\mathrm{c}}$ and ${\bar{D}}^{(\ast )}{\Sigma }_{\mathrm{c}}^{(\ast )}$
• Heavy Antiquark--Diquark Symmetry and Heavy Hadron Molecules: Are There Triply Heavy Pentaquarks?
• Doubly heavy hadrons and the domain of validity of doubly heavy diquark--anti-quark symmetry
• Study of exotic hadrons in S-wave scatterings induced by chiral interaction in the flavor symmetric limit
• Exotic baryons from a heavy meson and a nucleon - Positive parity states -
• Kondo effect in charm/bottom nuclei
• Kondo effect of ${\bar{D}}_s$ and ${\bar{D}}_s^{\ast }$ mesons in nuclear matter
• QCD sum rules for the anti-charmed pentaquark
• Anti-charmed pentaquark from B decays
• Open charm and bottom meson-nucleon potentials à la nuclear force
• Heavy baryons in the Skyrme model: the role of highly anharmonic collective motion
• Baryon Spectrum in Large N(C) Chiral Soliton and in Quark Models
• Masses and Magnetic Moments of Singly Heavy Pentaquarks
• Positive parity pentaquark towers in large Nc QCD
• R-Matrix Calculations for Few-Quark Bound States
• Mesic nuclei with a heavy antiquark
• Exotic baryons from a heavy meson and a nucleon
• Combined heavy-quark symmetry and large-$N_c$ operator analysis for 2-body counterterms in the chiral Lagrangian with $D$ mesons and charmed baryons