Possibility of Narrow High-Mass Exotic States
نویسندگان
چکیده
Narrow high-mass states can arise despite large phase space when two nearly degenerate states are coupled to the same dominant decay mode. Mixing via a final-state interaction loop diagram can produce one very broad state and one narrow state. Such a situation is generic in exotic hadrons where a color singlet with given flavor and spin quantum numbers can be constructed with two distinct internal color couplings of quarks. The simplest realization of this idea are the QQ̄qq̄ tetraquarks containing two heavy and two light quarks. We discuss possible experimental implications, including recent data from Belle. e-mail: [email protected] e-mail: [email protected]
منابع مشابه
Status of Pentaquark Search at Jlab
The possibility of the existence of pentaquarks has been theoretically discussed for many years. However, the subject has been thrust to the forefront during the past two years by the report of the possible observation of a such a state at Spring-8 [1] and ITEP [2]. This was immediately followed up by several positive signals from groups analyzing previously obtained data [3,4,5,6], so that at ...
متن کاملThe anticharmed exotic baryon Θ c and its relatives
Motivated by the recent discovery of the exotic S = +1 narrow baryon resonance Θ+ at 1540 MeV, with quark content uud ds̄, we conjecture the existence of its anti-charmed analogue Θcwith quark content uuddc̄, and compute its likely properties. We rely on the recently constructed model of a novel kind of a pentaquark with an unusual color structure which provides a good approximation to the Θ+ mas...
متن کاملCoupled-channel study of crypto-exotic baryons with charm
Identifying the t-channel exchange of vector mesons as the driving force for the s-wave scattering of pseudo-scalar mesons off the baryon ground states, a surprisingly rich spectrum of molecules is formed. We argue that chiral symmetry and large-Nc considerations determine that part of the interaction which generates the spectrum. All channels that are required by the existence of (u, d, s, c) ...
متن کاملExotic Hadronic States at Hera
The hadronic states studied in hadron spectroscopy have been successfully explained by quark-antiquark states (mesons) or three quark states (baryons). States whose quantum numbers could be understood in terms of more complex quark structures were up to now not observed. Such exotic states were already proposed on the basis of quark and bag models [1] in the early days of QCD, with the hope tha...
متن کاملIsospin Mixing of Narrow Pentaquark States
Interpreting the recently discovered narrow exotic baryons as pentaquark states, we discuss, along an old argument of ours, the isospin mixing occurring within the two doublets of Q = −1 and Q = 0 states lying inside the S = −2 (Ξ-cascade) sector. We argue that, at least within the Jaffe-Wilczek assignment, presently available data already indicate that mixing should occur at an observable leve...
متن کامل