abstract

The QCD running coupling constant is studied in the perturbative region, considering the existing experimental data, and also in the nonperturbative region, at low-momentum transfer. A continuous phenomenological function is determined by means of three different models also calculating the corresponding finite value of the vector quark self-energy. These two quantities are used for the vector interaction of a Dirac relativistic model for the charmonium spectrum. The process required to fit the spectrum is discussed and the relationship with previous models is analyzed.

abstract

A simple one-equilibrium memristor-based chaotic system (MCS) is established by combining a non-ideal memristor with a three-dimensional (3D) chaotic system with six polynomial terms. Its dynamical characteristics are studied and verified by some simulation experiments. The proposed MCS produces chaos via period-doubling bifurcation and maintains steady and robust chaotic behaviors unaffected by initial conditions. By changing the parameter values, the oscillation amplitudes of all the variables will be enlarged or shrunk on a large scale, indicating the existence of large-scale chaotic amplitude modulation. The finite-time synchronization (FTS) of the proposed MCS is studied, and the sufficient conditions of FTS based on simple feedback control are established via strict theoretical analysis. Numerical simulations demonstrate the correctness of the obtained results.

abstract

Effective field theories which describe the coupling between gravity and matter fields have recently been extended to include terms with operators of non-minimal mass dimension. These terms preserve the usual gauge symmetries but may violate local Lorentz and diffeomorphism invariance. The number of possible terms in the field theory explodes once one allows for non-minimal operators, with no criterion to choose between them. We suggest as such a criterion to focus on terms which violate Lorentz invariance via a (pseudo)vector background field, leaving a number of possible terms in the Higgs, gauge, and gravitational sectors. Further study of these terms is motivated by the proposed correspondence between the general effective theory for Lorentz violation and emergent Lorentz symmetry in condensed-matter systems, which is mostly unexplored for higher mass dimension operators and couplings to gauge fields and gravity. We suggest bounds in the Higgs sector and we show that some of the coefficients in the gauge sector vanish at one loop, whereas others have bounds which are comparable with those suggested by Kostelecký and Li for coefficients in Lorentz-violating QCD and QED coupled to quarks. We also find new bounds in the gravitational sector by considering the Robertson–Walker model. Finally, we discuss the special case where only diffeomorphism invariance is spontaneously broken and explain why it does not allow for non-trivial Nambu–Goldstone modes.

abstract

The structure of the neutron mid-shell \(^{115}_{\ 47}\)Ag\(_{68}\) nucleus was analyzed via Interacting Boson–Fermion Model (IBFM) calculations. Excited level energies and electromagnetic properties of \(^{115}\)Ag were calculated by using a proton hole coupled to an even–even \(^{116}\)Cd core described within the extended consistent \(Q\) formalism (ECQF). The new theoretical results are in a good agreement with the available experimental data and show a dominant \(\pi g_{9/2}\) component in the wave functions of the low-energy positive-parity states. The calculations provide insight into the ordering of the \(7/2^+_1\) and \(9/2^+_1\) states and the known \(j-1\) anomaly along the silver isotopic chain.