Narrow Results

The properties of new heavy mesons containing new heavy quarks have been investigated. As an example, the fourth SM family quarks and weak iso-singlet quarks predicted by E₆ GUT are considered. Production of these hadrons at TeV energy lepton colliders due to resonant formation of corresponding quarkonia have been analyzed.

The charged current neutrino–nucleon interaction cross-section is evaluated using Thermodynamical Bag Model (TBM) in the neutrino energy range 1 < E_ν < 200 GeV with the value of the four-momentum transfer squared 0.1 < Q² < 20 GeV² and the Bjorken variable 0.1 < x < 0.5. The hadronic current carries the linear moments of the reaction that depend on the Bjorken scaling variable x as well as the four-momentum transfer. The results obtained have been compared with the experimental values.

The ωϕ states with spin S=0,1 and 2 are dynamically studied in a chiral SU(3) quark model by solving the resonating group method (RGM) equation. It is found that the interactions of ωϕ systems are attractive, while no ωϕ bound state or resonance state is obtained due to the insufficiency of the strength of ωϕ attractions.

Lack of any baryon number in the eightfold way model, and its intrinsic presence in the SU(3)-flavor model, has been a puzzle since the genesis of these models in 1961–1964. First we show that the conventional popular understanding of this puzzle is actually fundamentally wrong, and hence the problem being so old, begs urgently for resolution. In this paper we show that the issue is linked to the way that the adjoint representation is defined mathematically for a Lie algebra, and how it manifests itself as a physical representation. This forces us to distinguish between the global and the local charges and between the microscopic and the macroscopic models. As a bonus, a consistent understanding of the hitherto mysterious medium–strong interaction is achieved. We also gain a new perspective on how confinement arises in quantum chromodynamics.

We consider the interplay of the pentaquark states and strange tetraquark states in the decay ${\Lambda }_b^0\to K^{-}J/\psi p$. Possible existence of ($cs\bar{c}ū$)-states is taken up and their manifestation in the $K^{-}J/\psi$-channel is discussed. It is emphasized that these exotic mesons can imitate broad bumps in the $pJ/\psi$-channel.

The diquark–diquark–antiquark model describes pentaquark states both in terms of quarks and hadrons. The latest LHCb data for pentaquarks with open charm emphasize the importance of hadron components in the structure of pentaquarks. We discuss pentaquark states with hidden charm $P(\bar{c}cuud)$ and those with open charm $P(ūussc)$ which were discovered recently in LHCb data ($J/\mathrm{\Psi }p$ and ${\mathrm{\Xi }}_c^{+}{K}^{-}$ spectra correspondingly). Considering the observed states as members of the lowest ($s$-wave) multiplet, we discuss the mass splitting of states and the dumping of their widths.

In a decade-and-a-half old experiment, Raabe et al. [Nature 431, 823 (2004)], had studied fusion of an incoming beam of halo nucleus ⁶He with the target nucleus ${}^{238}U$. We extract a new interpretation of the experiment, different from the one that has been inferred so far. We show that their experiment is actually able to discriminate between the structures of the target nucleus (behaving as standard nucleus with density distribution described with canonical RMS radius $r=r_0{A}^{\frac{1}{3}}$ with $r_0=1.2$ fm), and the “core” of the halo nucleus, which surprisingly, does not follow the standard density distribution with the above RMS radius. In fact, the core has the structure of a tennis-ball (bubble)-like nucleus, with a “hole” at the center of the density distribution. This novel interpretation of the fusion experiment provides an unambiguous support to an almost two decades old model [A. Abbas, Mod. Phys. Lett. A16, 755 (2001)], of the halo nuclei. This Quantum Chromodynamics based model succeeds in identifying all known halo nuclei and makes clear-cut and unique predictions for new and heavier halo nuclei. This model supports the existence of tennis-ball (bubble)-like core, of even the giant-neutron halo nuclei. This should prove beneficial to the experimentalists, to go forward more confidently, in their study of exotic nuclei.