119,694 research outputs found
Open charm tetraquarks in broken SU(3)_F symmetry
No full textPrompted by a recent lattice QCD calculation, we review the SU(3) light quark flavor structure of charmed tetraquarks with spin 0 diquarks. Fermi statistics forces the three light quarks to be in the representation 3¯⊗3¯=3⊕6¯. This agrees with the weak repulsion in the 15 of the 3⊗8 in D¯K scattering studied on the lattice. We analyze the 3⊕6¯ multiplet broken by the strange quark mass and determine the five independent masses from the known masses of diquarks. The mass of Ds0*(2317) is predicted within 50 MeV accuracy. The recently observed D¯s--(2900) and D¯s0(2900), likely part of a I=1 multiplet, with flavor composition c¯q¯q′s, and X0(2900), an isosinglet with flavor composition c¯s¯ud, fit naturally in a 3⊕6¯ structure as the first radial excitations. We discuss also the decay modes of Ds0*(2317), of the radial excitations and of the predicted particles.Prompted by a recent lattice QCD calculation, we review the SU(3) light quark flavor structure of charmed tetraquarks with spin-0 diquarks. Fermi statistics forces the three light quarks to be in the representation 3*x3*= 3+6*. This agrees with the weak repulsion in the 15 of the 3x8 in Dbar K scattering studied on the lattice. We analyze the 3+6* multiplet broken by the strange quark mass and determine the five independent masses from the known masses of diquarks. The mass of D^* _{s0}(2317) is predicted within 50 MeV accuracy. The recently observed D_s^{--}(2900) and D_s^0(2900), likely part of a I=1 multiplet, with flavor composition c* q* q' s and X_0(2900), an isosinglet with flavor composition c*s* ud, fit naturally in a 3+6* structure as the first radial excitations. We discuss also the decay modes of D^* _{s0}(2317), of the radial excitations and of the predicted particles
A note on the baryonic decay
No full textIn this short note we examine the exclusive three-body B --> Lambdabar p eta' decay using a simple pole model involving a scalar intermediate resonance state. We find that this channel could be quite sizeable in agreement with the recently formulated hypothesis that charmless baryonic B decays could occur mainly in association with eta' or gamma.In this short note we examine the exclusive three-body B --> Lambdabar p eta' decay using a simple pole model involving a scalar intermediate resonance state. Our aim is to test the recently formulated hypothesis that charmless baryonic B decays could occur mainly in association with eta' or gamma
A bbb ̄ b ̄ di-bottomonium at the LHC?
No full textWe study the case of a di-bottomonium bbb ̄ b ̄ particle at the LHC. Its mass and decay width are obtained within a new model of diquark–antidiquark interactions in tetraquarks. The same model solves several open problems on the phenomenology of the experimentally better known X, Z states. We show that the bbb ̄ b ̄ tetraquark is expected approximately 100 MeV below threshold, and compare to a recent analysis by LHCb seeking it in the Υ μμ final state
Gluonic mechanism for
No full textWe present a calculation of the process B --> D eta' within a heavy-light chiral quark model. We assume that the eta' has a large gluonic component, and its coupling is described via the glue-glue-eta' effective vertex. The main contribution comes from the non-factorizable part of the effective weak Lagrangian at quark level. We find, within our model-dependent assumptions, a branching ratio Br(B --> D eta') = (1.7 -- 3.3) 10^(-4), somewhat below the experimental upper bound 9.4 10^(-4).We present a calculation of the process B --> D eta' within a heavy-light chiral quark model. We assume that the eta' has a large gluonic component, and its coupling is described via the glue-glue-eta' effective vertex. The main contribution comes from the non-factorizable part of the effective weak Lagrangian at quark level. We find, within our model-dependent assumptions, a branching ratio Br(B --> D eta') = (1.7 -- 3.3) 10^(-4), somewhat below the experimental upper bound 9.4 10^(-4)
Tetraquarks in the 1/N expansion: A new appraisal
No full textWe discuss the necessary, albeit not sufficient, conditions for tetraquark poles to occur in the 1/N expansion of QCD and find the minimum order at which such poles may appear. Assuming tetraquark poles, we find a new nonplanar solution with the minimal number of topologies and tetraquark species. The solution implies narrow states. Mixing with quarkonium states is allowed so that P-wave tetraquarks with JPC=1 - would couple to e+e-
Sub-MeV dark matter and the Goldstone modes of superfluid helium
No full textWe show how a relativistic effective field theory for the superfluid phase of 4 He can replace the standard methods used to compute the production rates of low-momentum excitations due to the interaction with an external probe. This is done by studying the scattering problem of a light dark matter particle in the superfluid and comparing to some existing results. We show that the rate of emission of two phonons, the Goldstone modes of the effective theory, gets strongly suppressed for sub-MeV dark matter particles due to a fine cancellation between two different tree-level diagrams in the limit of small exchanged momenta. This phenomenon is found to be a consequence of the particular choice of the potential felt by the dark matter particle in helium. The predicted rates can vary by orders of magnitude if this potential is changed. We prove that the dominant contribution to the total emission rate is provided by excitations in the phonon branch. Finally, we analyze the angular distributions for the emissions of one and two phonons and discuss how they can be used to measure the mass of the hypothetical dark matter particle hitting the helium target.LPTPThis is an open access article under the terms of the Creative Commons Attribution Licens
A bb\bar{b}\bar{b} di-bottomonium at the LHC?
No full textWe study the case of a di-bottomonium bb\bar{b}\bar{b} particle at the LHC. Its mass and decay width are obtained within a new model of diquark–antidiquark interactions in tetraquarks. The same model solves several open problems on the phenomenology of the experimentally better known X, Z states. We show that the bb\bar{b}\bar{b} tetraquark is expected approximately 100 MeV below threshold, and compare to a recent analysis by LHCb seeking it in the \Upsilon\mu\mu final state
X (3872) tetraquarks in B and Bs decays
No full textWe 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
Hydrogen bond of QCD
No full textUsing 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
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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