Heavy baryon decay widths in the large N_{c} limit in chiral theory

Abstract We propose large $$N_c$$ Nc generalizations for the “diquark” representations of $$\hbox {SU}(3)_\mathrm{flav}$$ SU(3)flav relevant for positive parity heavy baryons, including putative exotic states. Next, within the framework of the Chiral Quark Soliton Model, we calculate heavy baryon masses and decay widths. We show that in the limit of $$N_c \rightarrow \infty$$ Nc→∞ all decay widths vanish, including the widths of exotica. This result is in fact more general than the model itself, as it relies only on the underlying symmetries: i.e. $$\hbox {SU}(3)_\mathrm{flav}$$ SU(3)flav and hedgehog symmetry. Furthermore, using explicit model formulae for the decay constants in the non-realtivistic limit, we show that there is a hierarchy of the decay couplings, which may explain observed pattern of experimental widths

Regge limit in QCD

It is shown that the perturbative calculations in Regge limit in nonabelian gauge theories are in agreement with the hypothesis of the reggeization of vector meson (gluon). The infrared properties of the integral equations for various quantum numbers exchange in the t-channel are studied in the spontaneously broken theory; the role of the Higgs particles is investigated. Some connections with deep inelastic scattering are also discussed. The integral equation describing the three gluon exchange in a colour singlet state is formulated and its infrared properties are studied. It is argued that it generates a fixed branch point in j-plane

Doubly heavy tetraquarks in the chiral quark soliton model

The chiral quark soliton model has been successfully applied to describe the heavy baryon spectrum, both for charm and bottom, leading to the conclusion that the heavy quark has no effect on the soliton. This suggests that replacing a heavy quark by a heavy antidiquark $\bar{Q}\bar{Q}$ in color triplet should give a viable description of heavy tetraquarks. We follow this strategy to compute tetraquark masses. To estimate heavy diquark masses, we use the Cornell potential with appropriately rescaled parameters. The lightest charm tetraquark is 70 MeV above the $DD^{*}$ threshold. On the contrary, both nonstrange and strange bottom tetraquarks are bound by approximately 140 and 60 MeV, respectively

Saturation and geometrical scaling : from small x deep inelastic ep scattering to high energy proton-proton and heavy ion collisions

Gluon distributions of colliding hadrons saturate as a result of the non-linear evolution equations of QCD. As a consequence there exists the so called saturation momentum, which is related to the gluon density per unit rapidity per transverse area. When saturation momentum is the only scale for physical processes, different observables exhibit geometrical scaling (GS). We show a number of examples of GS and its violation in different reactions

Chiral models : pions and baryons

Various aspects of chiral models are discussed with special emphasis on the chiral quark model and the Skyrme model. Firstly, the ability of the chiral quark model to reproduce pion scattering data is reviewed. Secondly the soliton sector of the model is studied. The soliton solution is interpreted as a baryon — nucleon or dilambda. Next, on the example of the Skyrme, model we study inclusion of strangeness, large limit and quantization. It is argued that effective chiral models qualitatively reproduce the low energy limit of QCD

Possibility of the existence of charmed exotica

We employ the chiral quark-soliton model to describe excited baryons with one heavy quark. Identifying known charmed baryons with multiplets allowed by the model, we argue that apart from regular excitations of the ground state multiplets, some of recently reported by the LHCb collaboration narrow $\Omega^{0}_{c}$ states, may correspond to the exotic pentaquarks. This interpretation can be easily verified experimentally, since exotic $\Omega^{0}_{c}$ states -- contrary to the regular excitations -- form isospin triplets, rather than singlets.Comment: 9 pages, 3 figures. Published version. The title has been changed as appeared in the journa

Invisible Charm Exotica

One possible interpretation of two narrow $\Omega^0_c$ states reported by the LHCb Collaboration at CERN in 2017 is that they are pentaquarks belonging to a $\overline{\boldsymbol{15}}$ exotic SU(3) representation, as predicted by the Chiral Quark--Soliton Model. If so, there must exist a number of other exotic states since the model predicts three different $\overline{\boldsymbol{15}}$ multiplets of heavy baryons. We show, that depending on the soliton spin $J$, these states are either very narrow or very broad. This explains why they might have escaped experimental observation. Furthermore, we show that the lightest members of these multiplets are stable against two body strong decays.Comment: 11 pages, 3 figures, v2 accepted in Phys. Rev.

Large Nc_{c} limit of the Skyrme model

In Skyrme model with 3 flavors the limit N$_{c}$ $\rightarrow \infty$ is explicitly performed. Mass splittings and magnetic moments for the baryonic states in such a model are calculated and compared with the data

Regge behaviour of symmetric octet exchange amplitude for gluon-gluon scattering

The Regge behaviour of the symmetric octet amplitude for gluon-gluon scattering in the massive SU(3)$_{c}$ theory is studied. It is shown that the asymptotic behaviour of this amplitude is controlled by a moving Regge pole similarly to the antisymmetric octet amplitude which is asymptotically described by the reggeised gluon. The corresponding Regge trajectories are, however, different and physical origin of this difference is discussed