Low-energy general relativity with torsion: a systematic derivative expansion

We attempt to build systematically the low-energy effective Lagrangian for the Einstein--Cartan formulation of gravity theory that generally includes the torsion field. We list all invariant action terms in certain given order; some of the invariants are new. We show that in the leading order the fermion action with torsion possesses additional U(1)_L x U(1)_R gauge symmetry, with 4+4 components of the torsion (out of the general 24) playing the role of Abelian gauge bosons. The bosonic action quadratic in torsion gives masses to those gauge bosons. Integrating out torsion one obtains a point-like 4-fermion action of a general form containing vector-vector, axial-vector and axial-axial interactions. We present a quantum field-theoretic method to average the 4-fermion interaction over the fermion medium, and perform the explicit averaging for free fermions with given chemical potential and temperature. The result is different from that following from the "spin fluid" approach used previously. On the whole, we arrive to rather pessimistic conclusions on the possibility to observe effects of the torsion-induced 4-fermion interaction, although under certain circumstances it may have cosmological consequences.Comment: 33 pages, 1 figure. A new section, discussion and references added. Final (published) versio

Клінічні ознаки та патологоанатомічні зміни в головному мозку за отруєння домашніх індиків діазиноном

For today, the actual problem of veterinary medicine is the poisoning of animals with organophosphorus pesticides, which are used as insecticides and acaricides, fungicides, herbicides, rodenticides, nematocides. One of the highly effective nonspecific organophosphorus insecticides is diazinon, which enters the body causing poisoning of various species of birds. The basis of the toxic action of diazinon is the ability to block the enzyme acetylcholinesterase. As a result, acetylcholine is accumulated in cholinergic synapses, excessive stimulation of the nerves and muscles is noted, and in the future, a violation of the normal passage of nerve impulses develops. Research was carried out of domestic turkeys (Meleagris gallopavo) in which spontaneous poisoning with diazinon was recorded. Detailed study of clinical signs that develop as a result of poisoning. The activity of the acetylcholinesterase of the serum of blood in the experimental birds was determined by the method of Hestrin. The section of birds that were killed was carried out by the method of Shore. Sections of organs were fixed in 10% neutral formalin, 96% ethanol and Carnoua liquid. The histo-cuttings were made by means of a stent microtome, stained with hematoxylin and eosin. The histological study of the preparations and their photographing was performed using a Leica DM-2500 (Switzerland) microscope, a Leica DFC450C camera and the Leica Application Suite Version 4.4 software. For the production of ultrathin sections, as well as for conducting electron microscopy, pieces of organs were fixed in Millonig’s buffer pH 7,36. Half-thin and ultrathin cuts were made on ultramicrotome LKB-2188 Ultrotome NOVA. The specimens were viewed and photographed in a Tesla BS-500 transmissive electron microscope, at an accelerating voltage of 60, 90 kV. In the pathoanatomical study, expressed discirculatory processes in the form of acute congestive hyperemia, stasis, perivascular edema and hemorrhages, as well as necrotic changes in cardiomyces, hepatocytes, nephrocytes and brain neurons. An electron microscopic study also found destruction of synapses in the cerebral cortex, cerebellum and medulla oblongata. When autopsy selected material (feed the masses crop of birds) for chemical-toxicological research. As a result the research the extract of selected content crop of birds by the method of thin-layer chromatography paper manifestation of iodine bismuth quality received positive reaction on the compound diazinon.Одним з високоефективних неспецифічних фосфорорганічних інсектицидів є діазинон, потрапляння якого в організм стає причиною отруєння різних видів птахів. В основi токсичної дiї діазинону лежить здатнiсть блокувати фермент ацетилхолінестеразу. Унаслідок цього ацетилхолiн нагромаджується в холінергічних синапсах, відзначається надмірна стимуляція нервів та м’язів, а надалі розвивається порушення нормального проходження нервових імпульсів. Структурні зміни в органах нервової системи за отруєння діазиноном вивчені недостатньо. Зважаючи на виключно важливе значення органів нервової системи в регуляції усіх життєвих функцій, вивчення структурних змін в головному мозку за отруєння діазиноном має наукове та практичне значення. Проведено комплексне дослідження домашніх індиків (Meleagris gallopavo) у яких реєстрували спонтанне отруєння діазиноном. Детально вивчали клінічні ознаки, що розвиваються унаслідок отруєння. Активність ацетилхолінестерази cироватки крові у дослідних птахів визначали за методом Хестріна. Розтин птахів, які загинули проводили за методом Шора. Фрагменти органів фіксували у 10% нейтральному формаліні, 96% етиловому спирті та рідині Карнуа. Гістозрізи виготовляли за допомогою санного мікротома та мікротома-кріостата, фарбували гематоксиліном та еозином, суданом-ІІІ за методом Ніссля. PAS-реакцію провели за Мак-Манусом. Для виготовлення ультратонких зрізів фрагменти органів фіксували у фіксаторі Міллоніга з рН 7,36. Напівтонкі та ультратонкі зрізи виготовляли на ультрамікротомі LKB-2188 Ultrotome NOVA. Напівтонкі зрізи фарбували метиленовим синім та основним фуксином. Зразки для трансмійної електронної мікроскопії переглядали і фотографували в електронному мікроскопі Tesla BS-500, за прискорюючої напруги 60, 90 kV. За отруєння діазиноном клінічно у хворих домашніх індиків відзначали різке пригнічення активності ацетилхолінестерази сироватки крові, що супроводжувалось вираженими симптоми ураження нервової системи. Реєстрували тремор та парези крил, порушення координації рухів, судоми та спастичні скорочення м’язів, плавальні рухи тазовими кінцівками, утруднене та часте дихання, що супроводжувалось хрипами. Унаслідок серцево-судинної та дихальної недостатності розвивалась гостра застійна гіперемія, що супроводжувалась вираженим ціаноз шкіри, За дослідження головного мозку реєстрували гіперемію, стази, діапедезні крововиливи, периваскулярні набряки, важкі зміни нервових клітин, деструкцію синапсів. Унаслідок проведення токсикологічного дослідження екстракту з відібраного вмісту вола індиків методом тонкошарової хроматографії на папері з проявленням йодвісмутовим реактивом отримано якісну позитивну реакцію щодо сполуки діазинон

Nature of the light scalar mesons

Despite the apparent simplicity of meson spectroscopy, light scalar mesons cannot be accommodated in the usual $q\bar q$ structure. We study the description of the scalar mesons below 2 GeV in terms of the mixing of a chiral nonet of tetraquarks with conventional $q\bar q$ states. A strong diquark-antidiquark component is found for several states. The consideration of a glueball as dictated by quenched lattice QCD drives a coherent picture of the isoscalar mesons.Comment: 14 pages, 1 figure, accepted for publication in Phys. Rev.

Observation of a narrow baryon resonance with positive strangeness formed in K+K^+Xe collisions

The charge-exchange reaction K^+ Xe --> K^0 p Xe' is investigated using the data of the DIANA experiment. The distribution of the pK^0 effective mass shows a prominent enhancement near 1538 MeV formed by \sim 80 events above the background, whose width is consistent with being entirely due to the experimental resolution. Under the selections based on a simulation of K^+Xe collisions, the statistical significance of the signal reaches 5.5\sigma. We interpret this observation as strong evidence for formation of a pentaquark baryon with positive strangeness, \Theta^+(uudd\bar{s}), in the charge-exchange reaction K^+ n --> K^0 p on a bound neutron. The mass of the \Theta^+ baryon is measured as m(\Theta^+) = 1538+-2 MeV. Using the ratio between the numbers of resonant and non-resonant charge-exchange events in the peak region, the intrinsic width of this baryon resonance is determined as \Gamma(\Theta^+) = 0.34+-0.10 MeV.Comment: 19 pages, 8 figure

Observation of a baryon resonance with positive strangeness in K+ collisions with Xe nuclei

The status of our investigation of low-energy $K^+$Xe collisions in the Xenon bubble chamber DIANA is reported. In the charge-exchange reaction $K^+Xe \to K^0 p Xe'$ the spectrum of $K^0 p$ effective mass shows a resonant enhancement with $M = 1539 \pm 2$ MeV/c$^2$ and $\Gamma \le 9 MeV/c$^2$. The statistical significance of the enhancement is near$4.4\sigma$. The mass and width of the observed resonance are consistent with expectations for the lightest member of the anti-decuplet of exotic pentaquark baryons, as predicted in the framework of the chiral soliton model.Comment: 9 pages, 4 figure

Further evidence for formation of a narrow baryon resonance with positive strangeness in K+ collisions with Xe nuclei

We have continued our investigation of the charge-exchange reaction K^+ Xe --> K^0 p Xe' in the bubble chamber DIANA. In agreement with our previous results based on part of the present statistics, formation of a narrow p K^0 resonance with mass of 1537+-2 MeV/c^2 is observed in the elementary transition K^+ n --> K^0 p on a neutron bound in the Xenon nucleus. Visible width of the peak is consistent with being entirely due to instrumental resolution and allows to place an upper limit on its intrinsic width: \Gamma < 9 MeV/c^2. A more precise estimate of the resonance intrinsic width, \Gamma = 0.36+-0.11 MeV/c^2, is obtained from the ratio between the numbers of resonant and non-resonant charge-exchange events. The signal is observed in a restricted interval of incident K^+ momentum, that is consistent with smearing of a narrow p K^0 resonance by Fermi motion of the target neutron. Statistical significance of the signal is some 7.3, 5.3, and 4.3 standard deviations for the estimators S/sqrt{B}, S/sqrt{S+B}, and S/sqrt{S+2B}, respectively. This observation confirms and reinforces our earlier results, and offers strong evidence for formation of a pentaquark baryon with positive strangeness in the charge-exchange reaction K^+ n --> K^0 p on a bound neutron.Comment: 13 pages, 8 figures, some chenges in text and references, more precise estimate of Theta(1540) to add, submitted to Phys.Atom.Nucl(Yad.Fiz.

Beyond Einstein-Cartan gravity: Quadratic torsion and curvature invariants with even and odd parity including all boundary terms

Recently, gravitational gauge theories with torsion have been discussed by an increasing number of authors from a classical as well as from a quantum field theoretical point of view. The Einstein-Cartan(-Sciama-Kibble) Lagrangian has been enriched by the parity odd pseudoscalar curvature (Hojman, Mukku, and Sayed) and by torsion square and curvature square pieces, likewise of even and odd parity. (i) We show that the inverse of the so-called Barbero-Immirzi parameter multiplying the pseudoscalar curvature, because of the topological Nieh-Yan form, can only be appropriately discussed if torsion square pieces are included. (ii) The quadratic gauge Lagrangian with both parities, proposed by Obukhov et al. and Baekler et al., emerges also in the framework of Diakonov et al.(2011). We establish the exact relations between both approaches by applying the topological Euler and Pontryagin forms in a Riemann-Cartan space expressed for the first time in terms of irreducible pieces of the curvature tensor. (iii) Only in a Riemann-Cartan spacetime, that is, in a spacetime with torsion, parity violating terms can be brought into the gravitational Lagrangian in a straightforward and natural way. Accordingly, Riemann-Cartan spacetime is a natural habitat for chiral fermionic matter fields.Comment: 12 page latex, as version 2 an old file was submitted by mistake, this is now the real corrected fil