On the double radiative decay of B_s-meson B→γγB\to\gamma\gamma

B_s-meson double radiative decay $B \to \gamma\gamma$ is investigated in frame of supersymmetric extension of the standard model. The branching ratio is calculated. It is shown that for light Higgs particle and heigh $\tan\beta$ supersymmetric contribution into branching ratio is significunt large than standard model estimate.Comment: 5 pages, latex, no figure

RURAL DEVELOPMENT – CHALLENGES, OPPORTUNITIES AND POLICY

The paper provides discussion about the administration arrangement of Georgia and assesses the possibilities of development of the regions in terms of existing approaches. The approaches to the economic development of the regions in Georgia don’t respond to the challenges faced by the country and fail to ensure the competitiveness of the regions. The study reveals the problem of regional inequity based on the different indicators, that show Georgia is strongly monocentric country with territorial, social and economic disparities. The research identifies common potentials of development for the most regions and emphasizes importance of determination the priorities of particular regions. The research focuses on the study of economic development models of regions in EU member countries. Considering international experience and on-going projects funded by EU to support regional development policy in Georgia, influence of EU cohesion policy will become more noticeable. That means there is a high chance that Georgian policy makers will focus on equity objective without relevant analysis and evaluation cost-benefit sides of both policy approaches. The paper presents recommendations that will facilitate the improvement of regional development strategy in Georgia and minimize problems which Georgia faces on the way of implementation of EU requirements / recommendations

Semileptonic Bc−→D∗0ℓνB_{c}^{-}\to D^{*0}\ell\nu transition in three--point QCD sum rules and HQET with gluon condensate corrections

Taking into account the gluon condensate contributions, the form factors of the semileptonic $B_c^- \to D^{*0}\ell\nu$ transition with $l=\tau, e$ are calculated in the framework of the three point QCD sum rules. The heavy quark effective theory limit of the form factors are also computed. The relevant total decay width as well as the branching ratio are evaluated and compared with the predictions of the other non-perturbative approaches.Comment: 27 Pages, 4 Figures and 4 Table

Mass-imbalanced ionic Hubbard chain

A repulsive Hubbard model with both spin-asymmetric hopping (t↑≠t↓) and a staggered potential (of strength Δ) is studied in one dimension. The model is a compound of the mass-imbalanced (t↑≠t↓,Δ=0) and ionic (t↑=t↓,Δ>0) Hubbard models, and may be realized by cold atoms in engineered optical lattices. We use mostly mean-field theory to determine the phases and phase transitions in the ground state for a half-filled band (one particle per site). We find that a period-two modulation of the particle (or charge) density and an alternating spin density coexist for arbitrary Hubbard interaction strength, U≥0. The amplitude of the charge modulation is largest at U=0, decreases with increasing U and tends to zero for U→∞. The amplitude for spin alternation increases with U and tends to saturation for U→∞. Charge order dominates below a value Uc, whereas magnetic order dominates above. The mean-field Hamiltonian has two gap parameters, Δ↑ and Δ↓, which have to be determined self-consistently. For UUc they have different signs, and for U=Uc one gap parameter jumps from a positive to a negative value. The weakly first-order phase transition at Uc can be interpreted in terms of an avoided criticality (or metallicity). The system is reluctant to restore a symmetry that has been broken explicitly

Ion Implantation as a Tool for Controlled Modification of Photoelectrical Properties of Silicon

The results of our recent studies of controlled modifications of the photoelectrical properties of n-Si due to B+ ion implantation are supplemented with new data, summarized and analyzed. The starting material was wafers of single-crystalline n-Si and a silicon-on-insulator structures. p-n-Si structures were fabricated by ion implantation of B+ in doses ranging from 1 × 1013 to 1 × 1015 сm−2 and ion acceleration energies of 50 and 32 keV. Subsequent annealing was performed both by steady-state (900 and 1000°C, 20 min) and pulsed photon processing. In such structures, a pronounced photosensitivity is observed in the short-wave infrared range (1.5–2.2 μm), as well as in the ultraviolet region within 0.25–0.40 μm. A well-defined correlation between the structural, electrical and photoelectrical properties and the implantation and annealing regimes, as well as the content of C and O impurities is demonstrated. In the starting material, a damaged layer with a thickness of hundreds of nanometers was found to have a significant effect on the results obtained. The main results are discussed in terms of the formation/transformation of deep-level extended defects in n-Si during B+ implantation followed by annealing. Innovative application approaches of the technology are obvious

Effective viscosity of microswimmer suspensions

The measurement of a quantitative and macroscopic parameter to estimate the global motility of a large population of swimming biological cells is a challenge Experiments on the rheology of active suspensions have been performed. Effective viscosity of sheared suspensions of live unicellular motile micro-algae (\textit{Chlamydomonas Reinhardtii}) is far greater than for suspensions containing the same volume fraction of dead cells and suspensions show shear thinning behaviour. We relate these macroscopic measurements to the orientation of individual swimming cells under flow and discuss our results in the light of several existing models

ნარკოტიკის მომხმარებელი C ჰეპატიტის ელიმინაციის პროგრამის ბენეფიციართა ინფორმირებულობა და ქცევა

The goal of the research was to check awareness and identify behavioral patterns of people engaged in Hepatitis C government program from 2015 and onwards. It must be mentioned, that every participant of this research is beneficiary of non-government organization New Vector and receive a service on Hepatitis C elimination program base. Methodology: The research was conducted using both Qualitative and Quantitative methods. On the early stages, using secondary information we analyzed general and demographic data, that provided information about research target’s social and economical wellbeing. Results: The research showed, that drug users engaged in Hepatitis C elimination program, are middle aged and unemployed men, which are engaged in unprotected sexual acts and injection patterns. The ratio of people with antibodies among the ones tested in organization was 26.3%. After confirmation tests the results were 42.6%. After qualitative research on three focus groups the main hepatitis C barriers were found out in general and in relation with drug usage. Recommendations: For main problems were identified: 1. Financial barrier – diagnostics should be free. 2. Geographical barrier – at least one regional center should be in regions of Georgia, that will work with one window principle. 3. Community awareness – destroying myths regarding involvment in programs. 4. Decriminalization - laws must be adjusted in favor of prevalence groups. Respondents awareness status is satisfactory, but it must be noted, that they gained the knowledge only after being infected and engaging in government program.კვლევის მიზანია საქართველოში 2015 წლიდან იმპლემენტირებული C ჰეპატიტის სახელმწიფო პროგრამის ფარგლებში ჩართული კონკრეტული სარისკო ჯგუფის წარმომადგენელთა, კერძოდ ნარკოტიკის მომხმარებელთა ინფორმირებულობისა და ქცევითი პატერნების გამოვლენა. ხაზგასასმელია ის ფაქტი, რომ კვლევაში მონაწილე ყველა რესპონდენტი წარმოადგენს არასამთავრობო სათემო ორგანიზაცია „ახალი ვექტორის“ ბენეფიციარებს, შესაბამისად, C ჰეპატიტის ელიმინაციის პროგრამით გათვალისწინებულ სერვისებს იღებენ სწორედ აღნიშნული ორგანიზაციის ბაზაზე. მეთოდოლოგია. კვლევა ჩატარდა როგორც რაოდენობრივი, ისე თვისებრივი კვლევის მეთოდების გამოყენებით. საწყის ეტაპზე, მეორეული მონაცემების ანალიზის საფუძველზე გამოვლინდა C ჰეპატიტის ელიმინაციის პროგრამაში ჩართული ნარკოტიკის მომხმარებელთა ზოგადი და დემოგრაფიული მაჩვენებლები, რამაც მოგვცა ინფორმაცია საკვლევი ჯგუფის სოციალურ-ეკონომიკური ფონის შესახებ. შედეგები. კვლევამ აჩვენა, რომ C ჰეპატიტის ელიმინაციის პროგრამაში ჩართულ ნარკოტიკის მომხმარებელ ბენეფიციარებს ძირითადად წარმოადგენენ საშუალო ასაკის დაუსაქმებელი მამაკაცები, რომლებიც ხასიათდებიან დაუცველი სქესობრივი კავშირებისა და ინექციური საშუალებების გაზიარების ქცევითი პატერნებით. ორგანიზაციაში ტესტირებაზე მისულ საერთო მაჩვენებელს შორის ანტისხეულების გამოვლენის პროცენტული წილი შეადგენს 26.3%, ხოლო კონფირმაციის ტესტის შედეგების მიხედვით, გამოვლენის მაჩვენებელი 42.6% - ით განისაზღვრა. თვისებრივი კვლევის ეტაპზე ჩატარებული სამი ფოკუსჯგუფის საფუძველზე კი გამოვლინდა C ჰეპატიტის ელიმინაციის პროგრამის ძირითადი ბარიერები როგორც ზოგადი, ისე უშუალოდ ნარკომომხმარებელთა კონტექსტის გვათვალისწინებით. დასკვნა, რეკომენდაციები. გამოიკვეთა ოთხი ძირითადი პრობლება და რეკომენდაციები მათი გადაჭრის კუთხით: 1. ფინანსური ბარიერი - დიაგნოსტიკა უნდა იყოს უფასო; 2. გეოგრაფიული ბარიერი - საქართველოს მაშტაბით მინიმუმ რაიონულ ცენტრებში უნდა იყოს ერთი დაწესბულება, რომელიც იმუშავებს ერთი ფანჯრის პრინიპით; 3. საზოგადოების ინფორმირებულობა - იმ მითების დამსხვრევა, რომლებიც საფრხებს უქმნის ადამიანების ჩართვას პროგრამაში; 4. დეკრიმინალიზაცია - აუცილებელია საკანონმდებლო ცვლილებები მაღალი პრევალენტობის ჯგუფების სასარგებლოდ. რესპონდენტთა ამჟამინდელი ცოდნა ჰეპატიტის ვირუსის შესახებ დამაკმაყოფილებელია, თუმცა, აღსანიშნავია, რომ მათ ეს ცოდნა შეიძინეს მხოლოდ საკუთარი სტატუსის გარკვევისა და პროგრამაში ჩართვის შემდეგ

Semileptonic B_c-meson decays in sum rules of QCD and NRQCD

The semileptonic B_c-meson decays into the heavy quarkonia J/\psi (\eta_c) and a pair of leptons are investigated in the framework of three-point sum rules of QCD and NRQCD. Calculations of analytical expressions for the spectral densities of QCD and NRQCD correlators with account for the Coulomb-like \alpha_s/v terms are presented. The generalized relations due to the spin symmetry of NRQCD for the form factors of B_c\to J/\psi (\eta_c)l\nu_l transitions with l denoting one of the leptons e, \mu or \tau, are derived at the recoil momentum close to zero. This allows one to express all NRQCD form factors through a single universal quantity, an analogue of Isgur-Wise function at the maximal invariant mass of lepton pair. The gluon condensate corrections to three-point functions are calculated both in full QCD in the Borel transform scheme and in NRQCD in the moment scheme. This enlarges the parameteric stability region of sum rule method, that makes the results of the approach to be more reliable. Numerical estimates of widths for the transitions of B_c\to J/\psi (\eta_c)l\nu_l are presented.Comment: 37 pages, Latex file, 10 figures, 15 epsf-insertions, revised version to appear in Nucl.Phys.

Propulsion efficiency of a dynamic self-assembled helical ribbon

We study the dynamic self-assembly and propulsion of a ribbon formed from paramagnetic colloids in a dynamic magnetic field. The sedimented ribbon assembles due to time averaged dipolar interactions between the beads. The time dependence of the dipolar interactions together with hydrodynamic interactions cause a twisted ribbon conformation. Domain walls of high twist connect domains of nearly constant orientation and negligible twist and travel through the ribbon. The particular form of the domain walls can be controlled via the frequency and the eccentricity of the modulation. The flux of twist walls—a true ribbon property absent in slender bodies—provides the thrust onto the surrounding liquid that propels this biomimetic flagellum into the opposite direction. The propulsion efficiency increases with frequency and ceases abruptly at a critical frequency where the conformation changes discontinuously to a flat standing ribbon conformation