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¯⊗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. Published by the American Physical Society 2024

New data from BESIII and LHCb show the existence of resonances with strangeness filling multiplets of the broken SU(3)_f symmetry, with the pattern predicted by the quark model. This is the case of the newly discovered Z_{cs} (3985) and Z_{cs}(4003), which have a natural accommodation in the tetraquark picture, as shown in this note. The quasi-degeneracy between Z_{cs} (3985) and Z_{cs}(4003) reproduces, in the strange sector, the situation observed with X(3872) and Z_c(3900). This represents a significative score in favor of the tetraquark scheme.

We briefly comment on the paper by Albaladejo et al., Chinese Phys. C 41 121001, rejecting its conclusions.

Diquarks are found to have the right degrees of freedom to describe the tetraquark poles in hidden-charm to open-charm meson-meson amplitudes. Compact tetraquarks result as intermediate states in non-planar diagrams of the 1/N expansion and the corresponding resonances are narrower than what estimated before. The proximity of tetraquarks to meson-thresholds has an apparent role in this analysis and, in the language of meson molecules, an halving rule in the counting of states is obtained.

We suggest that the J/psi phi structures observed by LHCb can be fitted in two tetraquak multiplets, the S-wave ground state and the first radial excitation, with composition [cs][(c) over bar(s) over bar]. When compared to the previously identified [cq][[(c) over bar(q) over bar] multiplet, the observed masses agree with that expected for a multiplet with q -> s. We propose the X(4274), fitted by LHCb with a single 1(++) resonance, to correspond rather to two, almost degenerate, unresolved lines with J(PC) = 0(++), 2(++). Masses of missing particles in the 1S and 2S multiplets are predicted.

The recent observation by the D0 collaboration of a narrow structure X(5568) consisting of four different quark flavors bdus, has not been confirmed by LHCb. In the tightly hound diquark model, we estimate the lightest bdus, 0(+) tetraquark at a mass of about 5770 MeV, approximately 200 MeV above the reported X(5568), and just 7 MeV below the B (K) over bar threshold. The charged tetraquark is accompanied by I = 1 and I = 0 neutral partners almost degenerate in mass. A bdus, S-wave, 1(+) quartet at 5820 MeV is implied as well. In the charm sector, cdus, 0(+) and 1(+) tetraquarks are predicted at 2365 and 2501 MeV, about 40-50 MeV heavier than D-s0 (2317) and D-s1 (2460). The bdus tetraquarks can be searched in the hadronic debris of a jet initiated by a b. However, some of them may also be produced in B-c decays, B-c -> X-b0 + pi with the subsequent decays X-b0 -> B-s + pi, giving rise to final states such as B-s pi(+)pi(0). We also emphasize the importance of B-c decays as a source of bound hidden charm tetraquarks, such as B-c -> X(3872) + pi.

The new data reported by ALICE on the production of light nuclei with p(1) less than or similar to 0 GeV in Pb-Pb collisions at root s(NN) = 2.76 TeV are used to compute an order-of-magnitude estimate of the expected production cross sections of light nuclei in proton-proton collisions at high transverse momenta. We compare the hypertriton, helium-3, and deuteron production cross sections to that of X(3872), measured in prompt pp collisions by CMS. The results we find suggest a different production mechanism for the X(3872), making questionable any loosely bound molecule interpretation.

In the context of the Minimal Supersymmetric extension of the Standard Model (MSSM), we reanalyze the search for the heavier CP-even H and CP-odd A neutral Higgs bosons at the LHC in their production in the gluon-fusion mechanism and their decays into gauge and lighter h bosons and into top quark pairs. We show that only when considering these processes, that one can fully cover the entire parameter space of the Higgs sector of the model. Indeed, they are sensitive to the low tanβ and high Higgs mass ranges, complementing the traditional searches for high mass resonances decaying into τ-lepton pairs which are instead sensitive to the large and moderate tanβ regions. The complementarity of the various channels in the probing of the complete [tanβ, M_A] MSSM parameter space at the previous and upcoming phases of the LHC is illustrated in a recently proposed simple and model independent approach for the Higgs sector, the hMSSM, that we also refine in this paper.

Pentaquarks and dibaryons are natural possibilities if diquarks are used as the building blocks to assemble hadrons. In this short note, motivated by the very recent discovery of two pentaquark states, we highlight some possible channels to search for dibaryons in Λb(5620) decays.

The observed \(Y(4260)\rightarrow \gamma + X(3872)\) decay is a natural consequence of the diquark–antidiquark description of Y and X resonances. In this note we attempt an estimate of the transition rate through a non-relativistic calculation of the electric dipole term of a diquarkonium bound state. Combining with BESIII data, upper bounds to \(B(Y\rightarrow J/\Psi +\pi +\pi )\) and to \(\Gamma (Y\rightarrow \mu ^+ \mu ^-)\) are obtained. We expect to confront these results with forthcoming data from electron–positron and hadron colliders.

Starting from an antibaryon, we get in first step: q̄q̄′[q1q2], namely a tetraquark, X,Y, Z. In the next step we obtain the pentaquark q̄[q1q2][q3q4]. The final step is one in which we replace all antiquarks in the baryon, saturating completely with diquarks the junction of three colored strings represented by the antisymmetric color tensor, ǫ . We obtain in this way a dibaryon, the B = 2 color bound alternative to the deuteron, with all its strange, charmed etc. variations. It seems a reasonable possibility that tetraquarks, pentaquarks and dibaryons make the next layer of hadron spectroscopy following the first layer made by the GellMann–Zweig baryons and mesons.

The observed Y(4260)→γ + X(3872) decay is a natural consequence of the diquark–antidiquark description of Y and X resonances. In this note we attempt an estimate of the transition rate through a non-relativistic calculation of the electric dipole term of a diquarkonium bound state. Combining with BESIII data, upper bounds to B(Y→ J/Ψ +π +π ) and to Γ (Y→μ ^+ μ ^-) are obtained. We expect to confront these results with forthcoming data from electron–positron and hadron colliders.

Assuming the dominance of the spin-spin interaction in a diquark, we point out that the mass difference in the beauty sector $M({Z}_{b}^{\ensuremath{'}}{)}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{-}M({Z}_{b}{)}^{\ifmmode\pm\else\textpm\fi{}}$ scales with quark masses as expected in QCD, with respect to the corresponding mass difference $M({Z}_{c}^{\ensuremath{'}}{)}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{-}M({Z}_{c}{)}^{\ifmmode\pm\else\textpm\fi{}}$. Notably, we show that the decays $\mathrm{\ensuremath{\Upsilon}}(10890)\ensuremath{\rightarrow}\mathrm{\ensuremath{\Upsilon}}(nS){\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ and $\mathrm{\ensuremath{\Upsilon}}(10890)\ensuremath{\rightarrow}({h}_{b}(1P),{h}_{b}(2P)){\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ are compatible with heavy quark spin conservation if the contributions of ${Z}_{b},{Z}_{b}^{\ensuremath{'}}$ intermediate states are taken into account, $\mathrm{\ensuremath{\Upsilon}}(10890)$ being either a $\mathrm{\ensuremath{\Upsilon}}(5S)$ or the beauty analog of ${Y}_{c}(4260)$. Belle results on these decays support the quark spin wave function of the $Z$ states as tetraquarks. We also consider the role of light quark spin nonconservaton in ${Z}_{b},{Z}_{b}^{\ensuremath{'}}$ decays into $B{B}^{*}$ and ${B}^{*}{B}^{*}$. Indications of possible signatures of the still missing ${X}_{b}$ resonance are proposed.

Pentaquark baryons are a natural expectation of an extended picture of hadrons where quarks and diquarks are the fundamental units. The parity/mass pattern observed, when compared to that of exotic mesons, appears as the footprint of a compact five-quark structure. What has been learned from the X,Y,Z phenomenology informs about the newly found pentaquark structure and suggests further experimental tests and directions to be explored.

Following the recent confirmation of the Z+(4430) resonance with J^{PG}=1^{++}, we have re-examined the model of S- and P-wave tetraquarks. We propose a `type-II' diquark-antidiquark model which shows to be very effective at producing a simple and comprehensive picture of the J^{PG}=1^{++} and 1^{--} sectors of the recently discovered charged tetraquarks and of the observed Y resonances. The model is still faced with the unresolved difficulty of explaining why some states seem to have incomplete isospin multiplets.

Recently we showed that the nuclear transmutation rates are largely overestimated in the Widom–Larsen theory of the so-called ‘Low Energy Nuclear Reactions’. Here we show that unbound plasma electrons are even less likely to initiate nuclear transmutations.

We update our analysis of the Higgs sector masses in Minimal Supersymmetry and in the Two-Higgs Doublet Model to the final ATLAS and CMS data from the 2011-2012 LHC run.