Effective potential at finite temperature in a constant hypermagnetic field: Ring diagrams in the Standard Model

We study the symmetry breaking phenomenon in the standard model during the electroweak phase transition in the presence of a constant hypermagnetic field. We compute the finite temperature effective potential up to the contribution of ring diagrams in the weak field, high temperature limit and show that under these conditions, the phase transition becomes stronger first order.Comment: 15 pages, 8 Postscript figure

Effective potential at finite temperature in a constant magnetic field I: Ring diagrams in a scalar theory

We study symmetry restoration at finite temperature in the theory of a charged scalar field interacting with a constant, external magnetic field. We compute the finite temperature effective potential including the contribution from ring diagrams. We show that in the weak field case, the presence of the field produces a stronger first order phase transition and that the temperature for the onset of the transition is lower, as compared to the case without magnetic field.Comment: Expanded comments, 4 figures added. Conclusions unchanged. Version to match published pape

Phase transition, radio- and photoluminescence of K3Lu(PO4)2 doped with Pr3+ ions

Luminescent characteristics of K3Lu(PO4)2:Pr3+ (1 and 5 mol.%) microcrystalline powders, a promising optical material for scintillation applications, were investigated using various experimental techniques. The material shows emission features connected with both high intensity interconfigurational 4f15d→4f2 transitions (broad UV emission bands) and intraconfigurational 4f2→4f2 transitions (weak emission lines in the visible range). The output of X-ray excited 4f15d→4f2 emission of Pr3+ increases with a temperature rise from 90 K to room tem- perature and higher depending on the Pr3+ ions concentration. The high 5% concentration of Pr3+ ions is found to be favourable for the stabilization of a monoclinic phase (P21/m space group) over a trigonal one (P3 space group) while emission properties of the material reveal that a phase transition occurs at higher temperatures. Decay kinetics of Pr3+ 4f15d→4f2 emission are recorded upon excitation with high repetition rate X-ray syn- chrotron excitation and pulse cathode ray excitation. Issues related to a non-exponential decay of luminescence and presence of slow decay components are discussed in terms of energy transfer dynamics. The presence of defects was revealed with thermoluminescence measurements and these are suggested to be the mainly responsible for delayed recombination of charge carriers on the Pr3+ 4f15d states. Some peculiarities of host-to- impurity energy transfer are discusse

Measurements of ZnWO4_4 anisotropic response to nuclear recoils for the ADAMO project

Anisotropic scintillators can offer a unique possibility to exploit the so-called directionality approach in order to investigate the presence of those Dark Matter (DM) candidates inducing nuclear recoils. In fact, their use can overcome the difficulty of detecting extremely short nuclear recoil traces. In this paper we present recent measurements performed on the anisotropic response of a ZnWO$_4$ crystal scintillator to nuclear recoils, in the framework of the ADAMO project. The anisotropic features of the ZnWO$_4$ crystal scintillators were initially measured with $\alpha$ particles; those results have been also confirmed by the additional measurements presented here. The experimental nuclear recoil data were obtained by using a neutron generator at ENEA-CASACCIA and neutron detectors to tag the scattered neutrons; in particular, the quenching factor values for nuclear recoils along different crystallographic axes have been determined for three different neutron scattering angles (i.e. nuclear recoils energies). From these measurements, the anisotropy of the light response for nuclear recoils in the ZnWO$_4$ crystal scintillator has been determined at 5.4 standard deviations.Comment: 22 pages; 12 figures. In press on Eur. Phys. J.

Developments and improvements of radiopure ZnWO4_{4} anisotropic scintillators

The ZnWO$_4$ is an anisotropic crystal scintillator; for its peculiar characteristics, it is a very promising detector to exploit the so-called directionality approach in the investigation of those Dark Matter (DM) candidates inducing nuclear recoils. Recently, in the framework of the ADAMO project, an R\&D to develop high quality and ultra-radiopure ZnWO$_4$ crystal scintillators has been carried out. In the present paper the measurements to study the anisotropic response of a ZnWO$_4$ to $\alpha$ particles and to nuclear recoils induced by neutron scattering are reported. Monochromatic neutrons have been produced by a neutron generator at ENEA-CASACCIA. The quenching factor values for nuclear recoils along different crystallographic axes have been determined for three different nuclear recoils energies. These results open the possibility to realize a pioneer experiment to investigate the above mentioned DM candidates by means of the directionality.Comment: Proceedings of the IPRD 2019 Conference, 10 pages, 7 figures, accepted for publication in JINS

Functional analysis of novel KCNQ2 and KCNQ3 gene variants found in a large pedigree with benign familial neonatal convulsions (BFNC)

Benign familial neonatal convulsion (BFNC) is a rare autosomal dominant disorder caused by mutations in KCNQ2 and KCNQ3, two genes encoding for potassium channel subunits. A large family with nine members affected by BFNC is described in the present study. All affected members of this family carry a novel deletion/insertion mutation in the KCNQ2 gene (c.761_770del10insA), which determines a premature truncation of the protein. In addition, in the family of the proposita's father, a novel sequence variant (c.2687A>G) in KCNQ3 leading to the p.N821S amino acid change was detected. When heterologously expressed in Chinese hamster ovary cells, KCNQ2 subunits carrying the mutation failed to form functional potassium channels in homomeric configuration and did not affect channels formed by KCNQ2 and/or KCNQ3 subunits. On the other hand, homomeric and heteromeric potassium channels formed by KCNQ3 subunits carrying the p.N821S variant were indistinguishable from those formed by wild-type KCNQ3 subunits. Finally, the current density of the cells mimicking the double heterozygotic condition for both KCNQ2 and KCNQ3 alleles of the proband was decreased by approximately 25% when compared to cells expressing only wild-type alleles. Collectively, these results suggest that, in the family investigated, the KCNQ2 mutation is responsible for the BFNC phenotype, possibly because of haplo-insufficiency, whereas the KCNQ3 variant is functionally silent, a result compatible with its lack of segregation with the BFNC phenotyp

Faraday rotation, stochastic magnetic fields and CMB maps

The high- and low-frequency descriptions of the pre-decoupling plasma are deduced from the Vlasov-Landau treatment generalized to curved space-times and in the presence of the relativistic fluctuations of the geometry. It is demonstrated that the interplay between one-fluid and two-fluid treatments is mandatory for a complete and reliable calculation of the polarization observables. The Einstein-Boltzmann hierarchy is generalized to handle the dispersive propagation of the electromagnetic disturbances in the pre-decoupling plasma. Given the improved physical and numerical framework, the polarization observables are computed within the magnetized $\Lambda$CDM paradigm (m$\Lambda$CDM). In particular, the Faraday-induced B-mode is consistently estimated by taking into account the effects of the magnetic fields on the initial conditions of the Boltzmann hierarchy, on the dynamical equations and on the dispersion relations. The complete calculations of the angular power spectra constitutes the first step for the derivation of magnetized maps of the CMB temperature and polarization which are here obtained for the first time and within the minimal m$\Lambda$CDM model. The obtained results set the ground for direct experimental scrutiny of large-scale magnetism via the low and high frequency instruments of the Planck explorer satellite.Comment: 53 pages, 15 included figure

Phase Transition, Radio- and Photoluminescence of K3Lu(PO4)2 Doped with Pr3+ Ions

Luminescent characteristics of K3Lu(PO4)2:Pr3+ (1 and 5 mol.%) microcrystalline powders, a promising optical material for scintillation applications, were investigated using various experimental techniques. The material shows emission features connected with both high intensity interconfigurational 4f15d→4f2 transitions (broad UV emission bands) and intraconfigurational 4f2→4f2 transitions (weak emission lines in the visible range). The output of X-ray excited 4f15d→4f2 emission of Pr3+ increases with a temperature rise from 90 K to room temperature and higher depending on the Pr3+ ions concentration. The high 5% concentration of Pr3+ ions is found to be favourable for the stabilization of a monoclinic phase (P21/m space group) over a trigonal one (P3‾ space group) while emission properties of the material reveal that a phase transition occurs at higher temperatures. Decay kinetics of Pr3+ 4f15d→4f2 emission are recorded upon excitation with high repetition rate X-ray synchrotron excitation and pulse cathode ray excitation. Issues related to a non-exponential decay of luminescence and presence of slow decay components are discussed in terms of energy transfer dynamics. The presence of defects was revealed with thermoluminescence measurements and these are suggested to be the mainly responsible for delayed recombination of charge carriers on the Pr3+ 4f15d states. Some peculiarities of host-to-impurity energy transfer are discussed. © 2020 Elsevier B.V.The work was partially supported by the Ministry of Science and Higher Education of the Russian Federation (through the basic part of the government mandate, project No. FEUZ-2020-0060), Act 211 Government of the Russian Federation (contract № 02.A03.21.0006), STSM grant from COST Action TD1401 ″FAST” as well as by Estonian Research Council (project PRG629) and Estonian Center of Excellence in Research “Advanced materials and high-technology devices for sustainable energetics, sensorics and nanoelectronics” TK141 (project No. 2014-2020.4.01.15-0011) by the ERDF funding in Estonia. The time-resolved X-ray excited measurements were performed at the Shared research center SSTRC based on the NovoFEL/VEPP-4 - VEPP-2000 facilities at Budker Institute of Nuclear Physics (Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia) while using experimental equipment funded by RFMEFI62119X0022 project. Authors thank Erica Viviani (University of Verona) for assistance in the synthesis of the samples and Yulya Khatchenko (UrFU, Ekaterinburg) for assistance in the processing the experimental data. F. P. and M. B. thank the Facility “Centro Piattaforme Tecnologiche” of the University of Verona for access to the Thermo ARL X’TRA powder diffractometer