1,721,067 research outputs found
Unstable Systems in Relativistic Quantum Field Theory
No full textWe show how the state of an unstable particle can be defined in terms of stable asymptotic states. This general definition is used to discuss and to solve some old problems connected with the short-time and large-time behaviour of the non-decay amplitude.We show how the state of an unstable particle can be defined in terms of stable asymptotic states. This general definition is used to discuss and to solve some old problems connected with the short-time and large-time behaviour of the non-decay amplitude
Hydrogen bond of QCD
Full text linkUsing the Born-Oppenheimer approximation, we show that exotic resonances, X and Z, may emerge as QCD molecular objects made of colored two-quark lumps, states with heavy-light diquarks spatially separated from antidiquarks. With the same method we confirm that doubly heavy tetraquarks are stable against strong decays. Tetraquarks described here provide a new picture of exotic hadrons, as formed by the QCD analog of the hydrogen bond of molecular physics
X (3872) tetraquarks in B and Bs decays
Full text linkWe discuss how the latest data on X(3872) in B and Bs decays speak about its tetraquark nature. The established decay pattern, including the up-to-date observations by CMS, are explained by the mixing of two quasidegenerate, unresolvable neutral states. The same mechanism also explains isospin violations in X decays and strongly suggests that the lurking charged partners are required to have very small branching fractions in J/ψρ±, well below the current experimental limits. In addition, a new prediction on the decay into J/ψω final states is attained. The newest experimental observations are found to give thrust to the simplest tetraquark picture and call for a definitive, in-depth study of final states with charged ρ mesons
NONPERTURBATIVE ASPECTS OF CHIRAL GAUGE-THEORIES - PROCEEDINGS OF THE TOPICAL WORKSHOP ON NONPERTURBATIVE ASPECTS OF CHIRAL GAUGE-THEORIES - ROME, ITALY 9-11 MARCH 1992 - PREFACE
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Hydrogen bond of QCD in doubly heavy baryons and tetraquarks
No full textIn this paper we present in greater detail previous work on the Born-Oppenheimer approximation to treat the hydrogen bond of QCD, and add a similar treatment of doubly heavy baryons. Doubly heavy exotic resonances X and Z can be described as color molecules of two-quark lumps, the analogue of the H2 molecule, and doubly heavy baryons as the analog of the H2+ ion, except that the two heavy quarks attract each other. We compare our results with constituent quark model and lattice QCD calculations and find further evidence in support of this upgraded picture of compact tetraquarks and baryons
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