Tetraquark Model Research Articles

Possible Tetraquark Explanation for the J/ψK0S Structure Observed in Proton-Proton Collision Data at Center-of-Mass Energies of 7, 8, and 13 TeV

Bevelacqua Resources, 7531 Flint Crossing Circle SE, Owens Cross Roads, AL 35763 USA bevelresou@aol.com The LHCb Collaboration provided data that supports a J/ψK0S structure, denoted as Tθψs1(4000)0, using an amplitude analysis of B0 → J/ψϕK0S decay. The structure of the J/ψK0S is investigated using a first-order tetraquark mass formula. This mass relationship is based on weakly bound J/ψ plus K0S meson clusters. The first-order tetraquark mass formula provides a predicted mass of 3694 MeV/c2 that is within about 8% of the experimental value of 3991 MeV/c2 with a Jπ = 1+ prediction. The data does not distinguish between 1+ and 1¯ states. KEYWORDS: Tetraquark Model for the Tθψs1(4000)0; First-Order Mass Formula; Quark Model; Cluster Model.

Possible Tetraquark Explanation for the ψ(4230), ψ(4360), and ψ(4415)

Bevelacqua Resources, 7531 Flint Crossing Circle SE, Owens Cross Roads, AL 35763 USA Ji et al. utilize heavy quark spin symmetry, to predict of the hadronic molecular characteristics of the ψ(4230), ψ(4360), and ψ(4415). Using symmetry arguments these states were identified by Ji et al. as DD1-bar, D*D1-bar, and D*D2*-bar bound states. The structure of the ψ(4230), ψ(4360), and ψ(4415) states are investigated using a first-order tetraquark mass formula. This mass relationship is based on weakly bound D plus D1-bar, D* plus D1-bar, and D* plus D2*-bar meson clusters. The first-order tetraquark mass formula provides predicted masses within about 3% of the experimental values, and the Jπ predictions are in agreement with values suggested by the data. However, the primitive angular momentum structure of the first-order mass model admit additional Jπ values. KEYWORDS: Tetraquark Model for the ψ(4230), ψ(4360), and ψ(4415); Mass Formula; Quark Model; Cluster Model.

The new [formula omitted] and [formula omitted] and the possible emergence of flavor pentaquark octets and tetraquark nonets

Our hadro-charmonium and compact tetraquark model predictions, published before the BESIII and LHCb experimental data for the $Z_{\rm cs}(3985)$ and $Z_{\rm cs}(4003)$ tetraquarks were released, match surprisingly well with them. Here, we extend our results for the $P_{\rm cs}$ states to $\Lambda$ + charmonium configurations and also our hadro-charmonium predictions for $Z_{\rm c}$ and $X_{\rm c}$ tetraquarks to charmonium + pion/eta. We use them, in combination with our previous findings, to discuss the possible emergence of SU(3)$_{\rm f}$ pentaquark octets and tetraquark nonets in the hidden-charm sector as a tool to discriminate among different theoretical interpretations.

Hunting for tetraquarks in ultraperipheral heavy ion collisions

Ultra-peripheral heavy ion collisions constitute an ideal setup to look for exotic hadrons because of their low event multiplicity and the possibility of an efficient background rejection. We propose to look for four-quark states produced by photon-photon fusion in these collisions at center-of-mass energy per nucleon pair $\sqrt{s_{\rm NN}}=5.5~{\rm TeV}$. In particular, we focus on those states that would represent a definite smoking gun for the compact tetraquark model. We show that the $X(6900)$, a likely $cc\bar{c}\bar{c}$ compact state, is a perfect candidate for this search, and estimate a production cross section ranging from around $250$ nb to $1150$ nb, depending on its quantum numbers. Furthermore, we discuss the importance of ultra-peripheral collisions to the search for the scalar and tensor partners of the $X(3872)$ predicted by the diquarkonium model, and not yet observed. The completion of such a flavor-spin multiplet would strongly speak in favor of the compact tetraquark model.

Hidden-charm and bottom tetra- and pentaquarks with strangeness in the hadro-quarkonium and compact tetraquark models

In two recent papers, we used the hadro-quarkonium model to study the properties of hidden-charm and bottom tetraquarks and pentaquarks. Here, we extend the previous results and calculate the masses of heavy-quarkonium-kaon/hyperon systems. We also compute the spectrum of hidden-charm and bottom tetraquarks with strangeness in the compact tetraquark (diquark-antidiquark) model. If heavy-light exotic systems with non-null strangeness content were to be observed experimentally, it might be possible to distinguish among the large variety of available theoretical pictures for tetra- and pentaquark states and, possibly, rule out those which are not compatible with the data.

Axial vector cc and bb diquark masses from QCD Laplace sum rules

Constituent mass predictions for axial vector (i.e., $J^P=1^+$) $cc$ and $bb$ colour antitriplet diquarks are generated using QCD Laplace sum-rules. We calculate the diquark correlator within the operator product expansion to NLO, including terms proportional to the four- and six-dimensional gluon and six-dimensional quark condensates. The sum-rules analyses stabilize, and we find that the mass of the $cc$ diquark is 3.51~GeV and the mass of the $bb$ diquark is 8.67~GeV. Using these diquark masses as inputs, we calculate several tetraquark masses within the Type-II diquark-antidiquark tetraquark model.

Search for muoproduction of the X(3872) at COMPASS

Exotic charmonium-like states have been observed by various experiments over the last 15 years, but their nature is still under discussion. Photo-(muo)production is a new promising instrument to study them. COMPASS, a fixed target experiment at CERN, analyzed the full set of the data collected with a muon beam between 2002 and 2011, covering the range from 7 GeV to 19 GeV in the centre-of-mass energy of the virtual photon-nucleon system. A signal in the mass spectrum of J/ψπ+π− with the statistical significance of 4.1 σ was observed in the reaction µ+N → µ+(J/ψπ+π−)π±N′. Its mass and width are consistent with those of the X(3872). The shape of the π+π− mass distribution from the observed decay into J/ψπ+π−is different from previous observations for X(3872). The observed signal may be interpreted as possible evidence of a new charmonium state (3872). It could be associated with a neutral partner of X(3872) with C = −1 predicted by a tetraquark model.

Search for muoproduction of X(3872) at COMPASS and indication of a new state [formula omitted

We have searched for exclusive production of exotic charmonia in the reaction μ+N→μ+(J/ψπ+π−)π±N′ using COMPASS data collected with incoming muons of 160 GeV/c and 200 GeV/c momentum. In the J/ψπ+π− mass distribution we observe a signal with a statistical significance of 4.1 σ. Its mass and width are consistent with those of the X(3872). The shape of the π+π− mass distribution from the observed decay into J/ψπ+π− shows disagreement with previous observations for X(3872). The observed signal may be interpreted as a possible evidence of a new charmonium state. It could be associated with a neutral partner of X(3872) with C=−1 predicted by a tetraquark model. The product of cross section and branching fraction of the decay of the observed state into J/ψπ+π− is determined to be 71±28(stat)±39(syst) pb.

JPG=1++charged resonance in theΥ(4260)→π+π−J/ψdecay?

New BES and Belle data show a peak in the $Y(4260)$ decay into $J/\ensuremath{\psi}$ plus one charged pion. We point out that the peak might correspond to a charged resonance at about 3880 MeV predicted some time ago within a tetraquark model. The same tetraquark model predicts another peak at about 100 MeV below the observed one. We discuss the possibility of having it in present data. On the other hand we expect that if the molecular picture were the correct one, a peak corresponding to a ${D}^{*}{\overline{D}}^{*}$ state should appear at about 4020 MeV.

New hadrons as four-quark states

Starting from the phenomenological evidence of four-quark structures in the scalar meson sector around 1 GeV, we investigate the predictions of a model based on diquark-antidiquark bound states, where the diquarks are assumed to contain also heavy quarks. The predictions are compared with the existing data in the charmonium energy range. A comparison of the tetraquark model with alternative interpretations of the exotic reson-cances is presented.

$D_{sJ}^*(2317)$, $D_{J}^*(2308)$ AND $D_{sJ}^*(2632)$ AS CANDIDATES FOR OPEN-CHARM TETRAQUARKS

We review the theoretical and experimental evidence for the candidacy of the [Formula: see text], [Formula: see text] and the [Formula: see text] for charmed tetraquarks. We briefly review the 't Hooft interaction's influence on the single-charm ( C =1)[Formula: see text] tetraquark mass spectrum: its consequences for other observed mesons such as the [Formula: see text], as well as its predictions of the (thus far) unobserved exotic tetraquark states. In particular we show that the near mass degeneracy of [Formula: see text] and [Formula: see text] was naturally predicted by the tetraquark model with 't Hooft interaction, and thus may constitute the first "smoking gun" evidence for tetraquark existence. A short outlook of possible future research directions is given.

$D_{sJ}^{*}(2317)$ AND $D_{J}^{*}(2308)$ AS CANDIDATES FOR OPEN-CHARM TETRAQUARKS

We review the theoretical and experimental evidence for the candidacy of the [Formula: see text] and the [Formula: see text] for charmed tetraquarks. We briefly review the 't Hooft interaction's influence on the single-charm (C = 1)[Formula: see text] tetraquark mass spectrum: its consequences for other observed mesons such as the [Formula: see text], as well as its predictions of the (thus far) unobserved exotic tetraquark states. In particular we show that the small [Formula: see text] mass difference is naturally predicted by the tetraquark model, within the present experimental error bars, and thus may constitute the first "smoking gun" evidence for tetraquark existence. A short outlook of the possible future research directions is given.