We investigate the possibility to describe the quark mass hierarchies as well as the CKM quark mixing matrix without fine-tuning in a quark flavour model with modular Formula omitted symmetry. The ...quark mass hierarchies are considered in the vicinity of the fixed point Formula omitted (the left cusp of the fundamental domain of the modular group), Formula omitted being the VEV of the modulus. The model involves modular forms of level 3 and weights 6, 4 and 2, and contains eight constants, only two of which, Formula omitted and Formula omitted, can be a source of CP violation in addition to the VEV of the modulus, Formula omitted, Formula omitted, Formula omitted. We find that in the case of real (CP-conserving) Formula omitted and Formula omitted and common Formula omitted ( Formula omitted) in the down-type and up-type quark sectors, the down-type quark mass hierarchies can be reproduced without fine tuning with Formula omitted, all other constants being of the same order in magnitude, and correspond approximately to Formula omitted. The up-type quark mass hierarchies can be achieved with the same Formula omitted but allowing Formula omitted and correspond to Formula omitted. In this setting the reproduction of the value of the CKM element Formula omitted is problematic. A much more severe problem is the correct description of the CP violation in the quark sector since it arises as a higher order correction in Formula omitted with Formula omitted. We show that this problem is somewhat alleviated in the case of complex Formula omitted and Formula omitted although the rephasing invariant Formula omitted is larger by a factor of Formula omitted than the correct value. A correct no-fine-tuned description of the quark mass hierarchies, the quark mixing and CP violation is possible with all constants being of the same order in magnitude and complex Formula omitted and Formula omitted, if one allows different values of Formula omitted in the down-type and up-type quark sectors, or in a modification of the considered model which involves modular forms of level 3 and weights 8, 6 and 4.
The full-heavy tetraquarks Formula omitted and Formula omitted are systematically investigated within a quark model. The meson-meson structure, diquark-antidiquark structure and K-structure are ...considered in this work. There is no bound state for Formula omitted and Formula omitted systems in Formula omitted and Formula omitted channels. However, for Formula omitted system, three possible resonance states with energy of Formula omitted, Formula omitted and Formula omitted are found in Formula omitted and Formula omitted, respectively, and their decay width Formula omitted are 6.7-8.4 MeV, 1.4-7.2 MeV and 9.1-11.1 MeV. For Formula omitted system, there also exist three possible resonance states with energy of Formula omitted, Formula omitted and Formula omitted in Formula omitted and Formula omitted, respectively, and the decay widths Formula omitted of them are 2.2-6.1 MeV, 2.2-6.9 MeV and 5.3-8.5 MeV. Formula omitted and Formula omitted systems will have the same results as Formula omitted and Formula omitted, respectively. These full-heavy resonance states are worthy to be searched in the future experiments.
Erratum to: Logarithmic corrections to O Husung, Nikolai
The European physical journal. C, Particles and fields,
04/2023, Letnik:
83, Številka:
4
Journal Article
We investigate flavour bounds on the Formula omitted and Formula omitted flavour symmetries. These flavour symmetries are a minimal and a non-minimal forms of the Formula omitted flavour symmetry, ...that can provide a simple set-up for the Froggatt-Nielsen mechanism. The Formula omitted and Formula omitted flavour symmetries are capable of explaining the fermionic masses and mixing pattern of the standard model including that of the neutrinos. The bounds on the parameter space of the flavon field of the Formula omitted and Formula omitted flavour symmetries are derived using the current quark and lepton flavour physics data and future projected sensitivities of quark and lepton flavour effects. The strongest bounds on the flavon of the Formula omitted symmetry come from the Formula omitted mixing. The bounds on the Formula omitted flavour symmetry are stronger than that of the minimal Formula omitted symmetry. The ratio Formula omitted provides rather robust bounds on the flavon parameters in the future phase-I and phase-II of the LHCb by leaving only a very small region in the allowed parameter space of the models.
We calculate the decay width of the Formula omitted using light-cone sum rules. For the initial quark radiation an effective Hamiltonian is constructed, where the internal quark line shrinks to a ...point. The final quark radiation is studied within the full theory. The leading twist light-cone distribution amplitudes of the Formula omitted serve as the non-perturbative input for the sum rules calculation, and the perturbative kernel is calculated at leading order. The branching fraction we obtain is Formula omitted, which is below the recent upper limits Formula omitted and Formula omitted given by the Belle collaboration and the BESIII collaboration, respectively.
In this work, we propose to search for the exotic doubly charmed meson Formula omitted and its analog Formula omitted in Formula omitted decays, which provide a good environment for the formation of ...the exotic state containing double charm quarks. Within the molecular scheme, the production of Formula omitted and Formula omitted through various rescattering processes with different intermediate states are investigated. For the moderate values of model parameters, the branching ratios of Formula omitted decaying into Formula omitted, Formula omitted, Formula omitted and Formula omitted are estimated to be of the order of Formula omitted, Formula omitted, Formula omitted and Formula omitted, respectively, which may be tested by future experiments.
We investigate the production of Formula omitted in the process Formula omitted, where Formula omitted is assumed to be a Formula omitted molecular state. Two kinds of meson loops of Formula omitted ...and Formula omitted were considered. To explore the rescattering mechanism, we calculated the relevant branching ratios using the effective Lagrangian based on the heavy quark symmetry. The branching ratios for the Formula omitted were found to be at the orders of Formula omitted. Such sizeable branching ratios might be accessible at BelleII, which would provide important clues to the inner structures of the exotic state Formula omitted.
We study Formula omitted and Formula omitted states assuming that they are hadronic molecules with Formula omitted quantum number. We use two-point QCD sum rule formalism and extract the mass and ...decay constant values of these states. We take into account contributions of various quark, gluon, and mixed vacuum condensates up to dimension eight. The extracted mass and decay constant values of Formula omitted and Formula omitted states read as Formula omitted, Formula omitted, and Formula omitted, Formula omitted, respectively. The predicted mass of Formula omitted state is in good agreement with the recent LHCb observation and supports quantum number and molecular picture assignments. A possible observation of Formula omitted state would help for establishing the lowest four-quark state in charmonium sector.
