Fragmentation of charmed quark to double-charmed hadrons

We consider the production of hadrons containing two charmed quarks in pp and ee collisions. We perform a numerical comparison of the fragmentation approach with the full calculation at $${{{\mathcal {O}}}}(\alpha _s^4)$$ O ( α s 4 ) . We conclude that the non-fragmentation contributions remain important up to transverse momenta as large as about 40 GeV, thus making questionable the applicability of the fragmentation approximation at smaller transverse momenta.

Study of exotic mesons in pp and AA collisions

The possibility of study of exotic mesons is discussed. The paper includes detailed analysis of strong, weak and electromagnetic decays containing charmed quark-antiquark pair, physics simulation and event reconstruction at NICA.

Parallel Realms

Electrons, their “brothers” neutrinos, and the quarks we are made of are a family. For each of these particles there exists two “copies” in Nature, two extra families. The first novel character in this clan, the “muon” (a cousin of the electron) had “not been ordered” by anyone. Nor had the first extra “strange” quark been ordered. Subsequently, the plot became much more interesting. The “November Revolution” subchapter recounts the theoretical prediction and discovery of the “charmed” quark. The third family was also “needed” (within what was to become the Standard Model of particle physics).

NEGATIVE PARITY TETRAQUARKS WITH THE OPEN CHARM

The relativistic four-quark equations are found in the framework of coupled-channel formalism. The dynamical mixing of the meson–meson states with the four-quark states is considered. The four-quark amplitudes of the negative parity tetraquarks including the quarks of three flavors (u, d, s) and the charmed quark are constructed. The poles of these amplitudes determine the masses of tetraquarks. The mass values of low-lying tetraquarks with the spin-parity JP = 0-, 1-, 2-, 3- are calculated.