Primordial black hole production due to preheating

During the preheating process at the end of inflation the amplification of field fluctuations can lead to the amplification of curvature perturbations. If the curvature perturbations on small scales are sufficiently large, primordial black holes (PBHs) will be overproduced. In this paper we study PBH production in the two-field preheating model with quadratic inflaton potential. We show that for many values of the inflaton mass m, and coupling g, small scale perturbations will be amplified sufficiently, before backreaction can shut off preheating, so that PBHs will be overproduced during the subsequent radiation dominated era.Comment: 5 pages, 3 eps figures. Minor changes to match version to appear in PRD as a rapid communicatio

Dark solitons in ferromagnetic chains with first- and second-neighbor interactions

We study the ferromagnetic spin chain with both first- and second-neighbor interactions. We obtained the condition for the appearance and stability of bright and dark solitons for arbitrary wave number inside the Brillouin zone. The influence of the second-neighbor interaction and the anisotropy on the soliton properties is considered. The scattering of dark solitons from point defects in the discrete spin chain is investigated numerically.Comment: 7 pages,5 figure

Heat tolerance of titanium boride and titanium nitride contacts to gallium arsenide

For contacts prepared from titanium borides by and nitrides ion-plasma sputtering onto gallium arsenide both formation mechanisms and thermal stability were investigated. We used a combination of structural, secondary-emission, optical and electrophysical methods, such as electronography, X-ray diffraction, atomic force microscopy, Auger electron spectroscopy, secondary-ion mass spectrometry, taking photoluminescence spectra and I - V curves. A physical model for contact formation was proposed. According to it, BxGa₁₋xAs (GaNxAs₁₋x) solid solutions are formed at the phase interfaces when titanium borides (nitrides) are deposited. The defects are produced in the semiconductor near-surface regions during heterostructure formation and further heat treatment. The correlation between the physico-chemical interactions at contact interfaces and the contact electrophysical parameters occurs through these defects. The objects of our investigation demonstrated high thermal stability. This was due to their two-layer structure formed by components having well-pronounced antidiffusion properties. As a result, the interdiffusion processes at the phase interfaces are drastically weakened

Chiral Lagrangian with confinement from the QCD Lagrangian

An effective Lagrangian for the light quark in the field of a static source is derived systematically using the exact field correlator expansion. The lowest Gaussian term is bosonized using nonlocal colorless bosonic fields and a general structure of effective chiral Lagrangian is obtained containing all set of fields. The new and crucial result is that the condensation of scalar isoscalar field which is a usual onset of chiral symmetry breaking and is constant in space-time, assumes here the form of the confining string and contributes to the confining potential, while the rest bosonic fields describe mesons with the q\bar q quark structure and pseudoscalars play the role of Nambu-Goldstone fields. Using derivative expansion the effective chiral Lagrangian is deduced containing both confinement and chiral effects for heavy-light mesons. The pseudovector quark coupling constant is computed to be exactly unity in the local limit,in agreement with earlier large N_c arguments.Comment: LaTeX2e, 17 page

Взаимосвязь полиморфных локусов, расположенных в промоторных областях генов VEGF (rs699947 и rs2010963), ICAM1 (rs281437) и ET-1 (rs1800541), с уровнем соответствующих белковых продуктов в сыворотке крови и риском развития алкогольного цирроза печени

Background: Uncontrolled use of alcohol can lead to the development of cirrhosis of the liver, which is manifested by fibrosis with the formation of regenerative nodes, an increase in pressure in the portal vein system and impaired liver function. Hepatic endothelium dysfunction during the formation of portal hypertension is accompanied by an increase in the level of protein molecules involved in the functioning of the endothelium: vascular endothelial growth factor A (VEGF-A), a soluble form of the intercellular adhesion molecule (s-ICAM-1) and endothelin-1 (ET -one). It is assumed that elevated levels of VEGF-A, s-ICAM-1 and ET-1 in alcoholic liver cirrhosis (AHC) may be interconnected with the structure of polymorphic loci, the promoter regions of the respective genes, which in turn may be a genetic risk factor for developing cirrhosis.Aims: Investigate the relationship of carriage of variant forms of polymorphic loci located in the promoter regions of VEGF-A, ICAM-1 and ET-1 with the level of the corresponding proteins in the blood serum and the risk of AHC.Materials and methods: The main group consisted of patients with pathological dependence on alcohol, aggravated by cirrhosis of the liver (AHC, n=60). The control group consisted of persons suffering from alcohol abuse, without liver pathology (AA, n=24). The observation period was the period of hospitalization. The serum levels of VEGF-A, s-ICAM-1 and ET-1 were evaluated by enzyme immunoassay. The distribution of variant forms of polymorphic loci located in the promoter regions of the VEGF-A genes (rs699947 and rs2010963), ICAM1 (rs281437) and ET-1 (rs1800541) in the studied sample was performed by real-time PCR.Results: The development of alcoholic cirrhosis was accompanied by a significant increase in the concentration of VEGF-A, s-ICAM-1 and ET-1 in serum. At the same time, direct correlations between the concentrations of VEGF-A, s-ICAM-1 and ET-1 in serum and the diameter of the portal vein in persons with liver cirrhosis were revealed. Patients with AHC are often carriers of the G allele of rs1800541 locus, located in the promoter of the ET-1 gene, compared with individuals suffering from control without liver pathology, which is associated with an increased risk of developing cirrhosis in alcohol dependence. The carriage of the C allele rs699947, as well as the C allele rs2010963 located in the promoter of the VEGF gene was associated with an increased level of VEGF-A in the AHC compared to carriers of this allele in the AA group. In addition, in the group of patients with AHC, carriers of allele C, homozygous CC genotype and heterozygous GC genotype of rs2010963 locus compared with carriers of G allele or homozygous GG genotype, respectively, were characterized by elevated serum VEGF-A levels.Conclusion: Carrier allele G of the rs1800541 locus (ET-1) is a risk factor for liver cirrhosis with alcohol abuse. The carriage of the C allele rs699947, as well as the C allele rs2010963 located in the promoter of the VEGF gene, can determine the elevated serum VEGF-A level in the AHC.Обоснование. Неконтролируемое употребление алкоголя может обусловливать развитие цирроза печени, который проявляется фиброзом с образованием узлов-регенератов, повышением давления в системе воротной вены и нарушением функции печени. Дисфункция печеночного эндотелия при формировании портальной гипертензии сопровождается повышением уровня молекул белковой природы, участвующих в функционировании эндотелия, ― васкулоэндотелиального фактора роста А (VEGF-A), растворимой формы молекулы межклеточной адгезии (s-ICAM-1) и эндотелина-1 (ET-1). Предполагается, что повышенный уровень VEGF-A, s-ICAM-1 и ET-1 при алкогольном циррозе печени (АЦП) может быть взаимосвязан со строением полиморфных локусов промоторных областей соответствующих генов, что в свою очередь может являться генетическим фактором риска развития цирроза печени.Цель ― исследовать взаимосвязь носительства вариантных форм полиморфных локусов, расположенных в промоторных областях VEGF-A, ICAM-1 и ET-1, с уровнем соответствующих белков в сыворотке крови и риском развития АЦП.Методы. Основную группу составили пациенты с патологической зависимостью от алкоголя, отягощенной циррозом печени (АЦП, n=60). Группу контроля составили лица, страдающие алкогольной зависимостью, без патологии печени (АЗ, n=24). Период наблюдения равнялся периоду госпитализации. Содержание VEGF-A, s-ICAM-1 и ET-1 в сыворотке крови оценивали посредством иммуноферментного анализа. Распределение вариантных форм полиморфных локусов, расположенных в промоторных областях генов VEGF-A (rs699947 и rs2010963), ICAM1 (rs281437) и ET-1 (rs1800541), в исследуемой выборке проводили с помощью полимеразной цепной реакции в режиме реального времени.Результаты. Развитие алкогольного цирроза печени сопровождалось значительным повышением концентрации VEGF-A, s-ICAM-1 и ET-1 в сыворотке крови. При этом были выявлены прямые корреляционные отношения между значениями концентрации VEGF-A, s-ICAM-1 и ET-1 в сыворотке крови и диаметром портальной вены у лиц с циррозом печени. Пациенты с АЦП чаще являются носителями аллеля G локуса rs1800541, расположенного в промоторе гена ET-1, по сравнению с лицами, страдающими АЗ без патологии печени, что сопряжено с повышенным риском развития цирроза при алкогольной зависимости. Носительство аллеля С локуса rs699947, а также аллеля С локуса rs2010963, расположенных в промоторе гена VEGF, было связано с повышенным уровнем VEGF-A при АЦП по сравнению носителями данного аллеля в группе АЗ. Кроме того, в группе пациентов с АЦП носители аллеля С, гомозиготного генотипа СС и гетерозиготного генотипа GC локуса rs2010963 по сравнению с носителями аллеля G или гомозиготного генотипа GG соответственно характеризовались повышенным уровнем VEGF-A в сыворотке крови.Заключение. Носительство аллеля G локуса rs1800541 (ET-1) является фактором риска развития цирроза печени при злоупотреблении алкоголем. Носительство аллеля С локуса rs699947, а также аллеля С локуса rs2010963, расположенных в промоторе гена VEGF, может определять повышенный уровень VEGF-А в сыворотке крови при АЦП

Effect of rapid thermal annealing on properties of contacts Au-Mo-TiBx-GaAs

The analytical, structural and electrophysical techniques have been applied to studies of the thermal degradation mechanism appearing in diode structures with the Schottky barrier Au-Mo-TiBxGaAs. It was shown that the rapid thermal annealing at T = 600 °C during 60 sec in hydrogen atmosphere results in creating the ELS type center in the space charge region of GaAs. This center is represented by the complex VGa+VAs, which has been confirmed by photoluminescence measurements. It causes the appearance of excess current at the initial part of current-voltage characteristic

Exotic Meson Production in the f1(1285)π−f_{1}(1285)\pi^{-} System observed in the Reaction π−p→ηπ+π−π−p\pi^{-} p \to \eta\pi^{+}\pi^{-}\pi^{-} p at 18 GeV/c

This letter reports results from the partial wave analysis of the $\pi^{-}\pi^{-}\pi^{+}\eta$ final state in $\pi^{-}p$ collisions at 18GeV/c. Strong evidence is observed for production of two mesons with exotic quantum numbers of spin, parity and charge conjugation, $J^{PC} = 1^{-+}$ in the decay channel $f_{1}(1285)\pi^{-}$. The mass $M = 1709 \pm 24 \pm 41$ MeV/c^2 and width $\Gamma = 403 \pm 80 \pm 115$ MeV/c^2 of the first state are consistent with the parameters of the previously observed $\pi_{1}(1600)$. The second resonance with mass $M = 2001 \pm 30 \pm 92$ MeV/c^2 and width $\Gamma = 333 \pm 52 \pm 49$ MeV/c^2 agrees very well with predictions from theoretical models. In addition, the presence of $\pi_{2}(1900)$ is confirmed with mass $M = 2003 \pm 88 \pm 148$ MeV/c^2 and width $\Gamma = 306 \pm 132 \pm 121$ MeV/c^2 and a new state, $a_{1}(2096)$, is observed with mass $M = 2096 \pm 17 \pm 121$ MeV/c^2 and width $\Gamma = 451 \pm 41 \pm 81$ MeV/c^2. The decay properties of these last two states are consistent with flux tube model predictions for hybrid mesons with non-exotic quantum numbers

Structural, magnetic and electrical properties of single crystalline La_(1-x)Sr_xMnO_3 for 0.4 < x < 0.85

We report on structural, magnetic and electrical properties of Sr-doped LaMnO_3 single crystals for doping levels 0.4 < x < 0.85. The complex structural and magnetic phase diagram can only be explained assuming significant contributions from the orbital degrees of freedom. Close to x = 0.6 a ferromagnetic metal is followed by an antiferromagnetic metallic phase below 200 K. This antiferromagnetic metallic phase exists in a monoclinic crystallographic structure. Following theoretical predictions this metallic antiferromagnet is expected to reveal an (x^2-y^2)-type orbital order. For higher Sr concentrations an antiferromagnetic insulator is established below room temperature.Comment: 8 pages, 7 figure

Search for the radiative decay η→π0γγ\eta \to \pi^0 \gamma \gamma in the SND experiment at VEPP-2M

The $\eta \to \pi^0 \gamma \gamma$ decay was investigated by the SND detector at VEPP-2M $e^+e^-$ collider in the reaction $e^+e^-\to\phi\to \eta\gamma$. Here we present the results and some details of this study. We report an upper limit (90% c.l.) $Br(\eta \to \pi^0 \gamma \gamma)<8.4\times 10^{-4}$ as our final result. Our upper limit does not contradict the earlier measurement by GAMS spectrometer. To facilitate future studies a rather detailed review of the problem is also given.Comment: 24 pages, 6 figures, LaTex. To be published in Nucl. Phys.

Nonanticommutative U(1) SYM theories: Renormalization, fixed points and infrared stability

Renormalizable nonanticommutative SYM theories with chiral matter in the adjoint representation of the gauge group have been recently constructed in [arXiv:0901.3094]. In the present paper we focus on the U*(1) case with matter interacting through a cubic superpotential. For a single flavor, in a superspace setup and manifest background covariant approach we perform the complete one-loop renormalization and compute the beta-functions for all couplings appearing in the action. We then generalize the calculation to the case of SU(3) flavor matter with a cubic superpotential viewed as a nontrivial NAC generalization of the ordinary abelian N=4 SYM and its marginal deformations. We find that, as in the ordinary commutative case, the NAC N=4 theory is one-loop finite. We provide general arguments in support of all-loop finiteness. Instead, deforming the superpotential by marginal operators gives rise to beta-functions which are in general non-vanishing. We study the spectrum of fixed points and the RG flows. We find that nonanticommutativity always makes the fixed points unstable.Comment: 1+30 pages, 5 figure