Effect of magnetic screening mass on the diffusion of heavy quarks

The drag and diffusion coefficients of heavy quarks propagating through quark–gluon plasma (QGP) have been estimated by shielding the infra-red divergences using electric and magnetic screening masses. The electric-type screening in perturbative quantum chromodynamics (pQCD) has been widely studied and used in evaluating the diffusion coefficient of heavy quarks (HQs). The impact of magnetic screening on diffusion coefficients of HQs is not studied before to the best of our knowledge. We explore the effect of magnetic screening mass on the drag and diffusion coefficients of HQs and found it to be non-negligible. Therefore, the effect of magnetic screening should be taken into consideration to characterize hot and dense matter formed in the collisions of nuclei at ultra-relativistic energies. We estimate the suppression of heavy flavored mesons in heavy ion collisions compared to proton+proton collisions at high transverse momenta and found that the suppression is less with the inclusion of magnetic screening. The value of the magnetic screening mass is not known exactly because of its nonperturbative nature. Moreover, it may not be possible to single out the effect of magnetic mass because of the uncertainties in other parameters involved in the diffusion process of HQs. Still it is important to include the effects of magnetic screening because of its physical origin in QCD.

A novel approach for the screening analysis of anticancer compounds from traditional Chinese medicine by a G-quadruplex functionalized magnetic system

G-quadruplex (G4) is a four-stranded DNA structure, viewed as an emerging therapeutic target in oncology. G4 coated magnetic screening system provides a feasible, easy-operating approach for anticancer drug discovery.

Эффекты близости и Джозефсона в бислоях из нитрида ниобия и алюминия

The highly disordered thin films of niobium nitride and features of the manifestation of the proximity effect in the NbN (S) –Aluminium (N) bilayers with a high ratio of their specific resistances NbN / Al >> 1were investigated. It was shown that the magnetic screening and critical current Ic of such SN structures significantly increase compared with the S layer. The observed effect is associated with the appearance of induced superconductivity in the N layer due to the proximity effect. The Josephson effect was demonstrated in the variable thickness bridges NbN / Al - NbN - NbN / Al made from such SN bilayers.

СВЧ-импеданс тонкопленочных гибридных структур сверхпроводник--нормальный металл с большим отношением проводимостей

Temperature dependence of linear electrodynamic response of thin-film hybrid structures superconductor (MoN) — normal metal (Al) with large ratio of normal-state conductivities was studied theoretically and experimentally. Low-frequency measurements of the mutual inductance of two coils with a sample placed between them indicated an increase in magnetic screening ability of the superconductor – normal metal (SN) hybrid structures at liquid helium temperatures as $d_Al$ increases, where $d_Al$ is the thickness of the Al layer. Measurements of the frequency shift $\delta f$ of the microwave dielectric resonator, which was in contact with the SN samples as a function of temperature and $d_Al$ demonstrated that (i) type of the $\delta f(T)$ dependence depends significantly on $d_Al$ and (ii) the shift of resonant frequency of the SN structures at temperatures close to the critical temperature Tc cannot be approximated by a functional dependence $const/(1–T/T_c)$, which is typical for thin superconducting films. Numerical calculations performed within the Usadel model describe the observed effects quite well. Thus, the mentioned anomalies of the electrodynamic properties of the SN hybrid structures can be explained by an appearance of a mini-gap in the spectrum of quasi-particle excitation caused by the proximity effect in the normal metal layer, which depends on $d_Al$ as well as by the high conductivity of the Al layer.

Confinement, chiral symmetry breaking and the effective quark mass

Paradigm shift in gauge topology, from instantons to their constituents — instanton-dyons — has recently lead to very significant advances. Unlike instantons, these objects have three different set of charges, therefore allowing to explain and to tie together several important phenomena: confinement, chiral symmetry breaking and magnetic screening.