Electron energy spectrum of the spin-liquid state in a frustrated Hubbard model

Non-local correlation effects in the half-filled Hubbard model on an isotropic triangular lattice are studied within a spin polarized extension of the dual fermion approach. A competition between the antiferromagnetic non-collinear and the spin liquid states is strongly enhanced by an incorporation of a k-dependent self-energy beyond the local dynamical mean-field theory. The dual fermion correc- tions drastically decrease the energy of a spin liquid state while leaving the non-collinear magnetic states almost non-affected. This makes the spin liquid to become a preferable state in a certain interval of interaction strength of an order of the magnitude of a bandwidth. The spectral function of the spin-liquid Mott insulator is determined by a formation of local singlets which results in the energy gap of about twice larger than that of the 120 degrees antiferromagnetic Neel state.Comment: 6 pages, 4 figure

Radiative corrections to neutral pion-pair production

We calculate the one-photon loop radiative corrections to the neutral pion-pair photoproduction process $\pi^-\gamma \to \pi^-\pi^0\pi^0$. At leading order this reaction is governed by the chiral pion-pion interaction. Since the chiral $\pi^+\pi^-\to\pi^0\pi^0$ contact-vertex depends only on the final-state invariant-mass it factors out of all photon-loop diagrams. We give analytical expressions for the multiplicative correction factor $R\sim \alpha/2\pi$ arising from eight classes of contributing one-photon loop diagrams. An electromagnetic counterterm has to be included in order to cancel the ultraviolet divergences generated by the photon-loops. Infrared finiteness of the virtual radiative corrections is achieved (in the standard way) by including soft photon radiation below an energy cut-off $\lambda$. The radiative corrections to the total cross section vary between $+2\%$ and $-2\%$ for center-of-mass energies from threshold up to $7m_\pi$. The finite part of the electromagnetic counterterm gives an additional constant contribution of about $1\%$, however with a large uncertainty.Comment: 10 pages, 6 figures, submitted to Eur. Phys. J.

Available drugs during of military state: social-economic strategies of functioning reimbursumen’t system

The Russian aggresion against Ukraine became a new reality in the XXI century and definitely shook the whole World. New realities are forcing all spheres of science and practice to work harder and develop, that is why philosophers of law are tended to call war “the driving force of progress”. Our modern life in the condition of war proves, that the technical and scientific progress as it is, is created and developed on thousands and millions of destroyed human lives. But, in order to make a warring society to move successfully forward, save as many innocent lives as possible and meet basic needs of a particularly vulnerable polutation, it is not only army, which is supposed to work for 100%, but also “home front workers” has to try harder. The current war has dimished an understanding of difference between quintiles of population, especially, if we are taking into account differences between beneficiaries of the Affordable Medicines Program (AM). At the beginning of the War, all beneficiaries of the AM, despite of level of their well-being had to suffer equally because of the short-term period of medicines’ shortage due to destroyed infrastructure of cities and regions. They were afraid that those highly necessary medicines would not return to the pharmacies neither in the sphere of the AM, nor even for normal sale. Because of the aforementioned force-majeure, most of people were not even assured that their basic needs will be met, especially were worried those ones, who have been active users of the AM for a long period of time. However, despite of the aforementioned destruction of the insfrastrucutre, the commons fears and dangers of war, the AM has not stopped working. On the contrary, it has become even more successful and progressive. The need to react quickly to the circumstances that took place, forced to achieve long-term plans of the AM creators in a very short time. Thus, the pilot program has finally fit into the general outline of the life support and health care system of Ukraine and became perhaps the most progressive in the whole Europe. But, nevertheless, the progress is definitely not standing still, the situation remains critical, the humanitarian catastrophe is becoming more and more real today, and, thus, the AM opens new promising ways of development for the coming month and years. In fact, our study was devoted to the analysis of the changes that took place since February 24, 2022, as well as promising directions for the development of AM, which are mostly dictated by the newly created humaniatrian crises in the current article.Новою реалією ХХІ століття стала загарбницька війна Росії проти України, яка без сумніву сколихнула цілий світ. Нові реалії життя змушують всі сфери науки і практики працювати у посиленому режимі та розвиватись, саме тому філософи права називають війну “рушійною силою прогресу”. Сучасне життя доводить, що технічний і науковий прогрес, як виявилось, створюється і розвивається на тисячах і мільйонах зруйнованих людських життів. Але, задля того, щоб суспільство країни, що воює, змогло рухатись далі, змогло врятувати якумога більше безвинних життів та забезпечувати базові потреби особливо вразливого контингенту населення, не тільки армія, але й “герої тилу”, тобто медики і вся система охорони здоров’я мають працювати на 100%, як це власне і відбувається зараз. Війна знизила важливість понять “квінтилі населення”, особливо якщо йдеться про прямих бенефіціарів програми “Доступні ліки”, адже серед них всі, незалежно від особистого та фінансового благополуччя, були піддані необхідності страждати від першострокової нестачі ліків, які забезпечувались програмою; були підвергнуті страху, що ці ліки не повернуться не тільки в рамках програми Доступні ліки (ДЛ), але і в принципі будуть недоступні через знищену інфраструктуру багатьох міст, а отже здійснився такий force majeure, при якому жодна людина не могла бути впевнена у власному забезпеченні навіть базових потреб, і особливо ті, хто протягом тривалого часу вже був активним користувачем ДЛ. Тим не менш, не дивлячись на вищезгадану зруйновану інфраструктуру, загальні страх і небезпеку, які приносить із собою війна, програма ДЛ не припинила свою роботу, навпаки, стала навіть більш прогресивною і успішною. Необхідність стрімко реагувати на обставини, які мали місце з погляду на війну, змусили досягнути довготривалі плани творців ДЛ за дуже короткий термін. Таким чином, пілотна програма остаточно вписалась в загальну канву системи життєзабезпечення та охорони здоров’я України і стали чи не найбільш прогресивною в цілій Європі. Але, тим не менш, прогрес безумовно не стоїть на місці, ситуація залишається критичною, гуманітарна катастрофа стає все більш реальною на сьогоднішній день, а отже ДЛ відкриває нові перспективні шляхи розвитку на найближчі місяці і роки. Власне аналізові змін, які мали місце, починаючи від 24-го лютого 2022 року, а також перспективним напрямкам розвитку ДЛ, які здебільшого продиктовані новоствореними гуманітраними кризами населення нашої країни, які мали місце через війну, і було присвячено наше дослідження, результати якого будуть освітлені у нинішній статті

High pressure effects in fluorinated HgBa2Ca2Cu3O(8+d)

We have measured the pressure sensitivity of Tc in fluorinated HgBa2Ca2Cu3O(8+d) (Hg-1223) ceramic samples with different F contents, applying pressures up to 30 GPa. We obtained that Tc increases with increasing pressure, reaching different maximum values, depending on the F doping level, and decreases for a further increase of pressure. A new high Tc record (166 K +/- 1 K) was achieved by applying pressure (23 GPa) in a fluorinated Hg-1223 sample near the optimum doping level. Our results show that all our samples are at the optimal doping, and that fluorine incorporation decreases the crystallographic $a$-parameter concomitantly increasing the maximum attainable Tc. This effect reveals that the compression of the $a$ axes is one of the keys that controls the Tc of high temperature superconductors.Comment: 4 pages, 4 figures, submitted to Phys. Rev.

Synthesis of Single Phase Hg-1223 High Tc Superconducting Films With Multistep Electrolytic Process

We report the multistep electrolytic process for the synthesis of high Tc single phase HgBa2Ca2Cu3O8+ (Hg-1223) superconducting films. The process includes : i) deposition of BaCaCu precursor alloy, ii) oxidation of BaCaCu films, iii) electrolytic intercalation of Hg in precursor BaCaCuO films and iv) electrochemical oxidation and annealing of Hg-intercalated BaCaCuO films to convert into Hg1Ba2Ca2Cu3O8+ (Hg-1223). Films were characterized by thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrolytic intercalation of Hg in BaCaCuO precursor is proved to be a novel alternative to high temperature-high pressure mercuration process. The films are single phase Hg-1223 with Tc = 121.5 K and Jc = 4.3 x 104 A/cm2.Comment: 17 Pages, 10 Figures. Submitted to Superconductor Science and Technolog

Phenomenological study of light (anti)nuclei, (anti)hypertriton and di-Lambda production at RHIC

We present the production of light (anti)nuclei, (anti)hypertriton and di-Lambda based on coalescence model in central Au+Au collisions at $\sqrt{s_{NN}}=200GeV$. The invariant yields of \He(\Hebar), \hypert(\hypertbar), \Hee(\Heebar) obtained is found to be consistent with the STAR measurements. The $p_{T}$ integrated yields for di-Lambda $dN_{\Lambda\Lambda}/dy \sim 2.23\times10^{-5}$, and is not strongly dependent on the parameter employed for coalescence process. Relative particle ratios of light anti(nuclei) and (anti)hypertriton are explored, and agree with experimental data and thermal model predictions quite well. An exponential reducion behavior is presented for the differential invariant yields with increased baryon number. The production rate reduces by a factor of 1692 (1285) for each additional antinucleon (nucleon) added to antinuclei (nuclei), and the production rate of \Libar is predicted to be $10^{-16}$ which is consistent with STAR result.Comment: 4 pages, 3 figures parallel talk delivered by L. Xue at the 14th national conference on nuclear structure, April 12nd - 16th, 2012, Huzhou, Chin

Role of rotational symmetry in the magnetism of a multiorbital model

Effect of rotationally invariant Hund's rule coupling on a magnetism of multiorbital Hubbard models is studied within a dynamical mean-field theory framework. Comparison of static magnetic susceptibilities and local densities of states of two- and three-orbital models of a complete rotationally invariant Coulomb interaction and a "density-density" Hartree type interaction shows the different role of spin-flip interactions for different band fillings. In the particle-hole symmetric case, the Mott-Hubbard physics dominates due to the strong effective Coulomb interaction, while for the multiple electronic configurations away from half-filling (two electrons in the three-band model) the formation of local magnetic moments due to Hund's exchange interaction becomes the most significant effect for itinerant magnetic systems. A shift of the temperature of magnetic ordering due to the rotationally invariant Hund's rule coupling is found to be the largest in a three-orbital model with a two-electron occupancy where the single particle spectrum is metallic and is not sensitive to different forms of the Coulomb vertex. A larger enhancement of the effective mass in a model with a rotationally invariant interaction is discussed. In the half-filled case we find a drastic change in the density of states close to the Mott transition which is related to the spin-flip Kondo fluctuations in a degenerate orbital case, while the corresponding shift of the magnetic transition temperature is relatively small. It is shown that a change in the ground-state degeneracy due to a different symmetry of the Coulomb interaction in the density-density model leads to a breakdown of the quasiparticle peak at the Fermi level in the proximity of a Mott transition on the metallic side. We discuss the relevance of rotationally invariant Hund's interaction in the transition metal magnetism. © 2012 American Physical Society

Chiral Anomaly and γ3π\gamma 3\pi

Measurement of the $\gamma 3\pi$ process has revealed a possible conflict with what should be a solid prediction generated by the chiral anomaly. We show that inclusion of appropirate energy-momentum dependence in the matrix element reduces the discrepancy.Comment: 8 page standard Latex fil