Radiative Corrections for Pion Polarizability Experiments

We use the semi-analytical program RCFORGV to evaluate radiative corrections to one-photon radiative emission in the high-energy scattering of pions in the Coulomb field of a nucleus with atomic number Z. It is shown that radiative corrections can simulate a pion polarizability effect. The average effect was estimated for pion energies 40-600 GeV. We also study the range of applicability of the equivalent photon approximation in describing one-photon radiative emission.Comment: 11 pages (LaTex), 6 figures, 1 table. No changes in the paper. New submission because old files are corrupted in arXi

Quadrupole polarizabilities of the pion in the Nambu--Jona-Lasinio model

The electromagnetic dipole and quadrupole polarizabilities of the neutral and charged pions are calculated in the Nambu--Jona-Lasinio model. Our results agree with the recent experimental analysis of these quantities based on Dispersion Sum Rules. Comparison is made with the results from the Chiral Perturbation Theory.Comment: 9 pages, 1 fi

Эпидемиология эндопротезирования тазобедренного и коленного суставов и перипротезной инфекции в Российской Федерации

Background. Since there is no national arthroplasty registry in the Russian Federation, the exact number of arthroplasty operations performed is unknown. Aim of the study to evaluate the epidemiology of primary, revision hip and knee arthroplasty and periprosthetic joint infection in Russian Federation. Materials and Methods. The inquires were made to 85 subjects, 73 federal state budget institutions and 30 private hospitals. Results. Answers were received from 76 subjects of Russian Federation, 41 federal and 18 private hospitals. The studied indicators revealed to be pretty much heterogenic. The decrease of operations number from 20% to 40% in subjects of Russian Federation due to SARS-CoV-2 pandemic forced us to make no analysis for these 2020 indicators in Russian Federation generally. 147 061 primary hip and knee arthroplasties were performed in 2019 in Russian Federaion. 7 770 revison hip and knee arthroplasties were done. 6 606 cases of severe orthopaedic implant-assosiated infection were cured including 4 282 cases post hip and knee arthroplasties that constitutes 2,91 % from primary arthroplasties. Conclusions. The frequency of periprosthetic joint infection in Russian Federation correlates to the world data. High complexity for patients routing with implant-assosiated infection and strong demand for Federal Center of implant-assosiated orthopaedic infection are revealed.Актуальность. Поскольку в Российской Федерации отсутствует национальный регистр артропластики, точное число выполненных операций эндопротезирования неизвестно. Цель изучить эпидемиологию эндопротезирования коленного и тазобедренного суставов, а также перипротезной инфекции (ППИ) в Российской Федерации (РФ). Материал и методы. Сделаны запросы в 85 субъектов, 73 федеральных государственных бюджетных учреждения и 30 частных учреждений здравоохранения. Результаты. Получены ответы из 76 субъектов РФ, 41 федерального и 18 частных учреждений здравоохранения. В 2020 г. установлена значительная гетерогенность изучаемых показателей: снижение числа операций составило от 20 до 40% в различных субъектах РФ в связи с пандемией SARS-CoV-2, поэтому показатели 2020 г. решено было не анализировать по России в целом. В 2019 г. в РФ выполнено 147 061 операций первичного эндопротезирования коленного и тазобедренного суставов, 7 770 ревизионных артропластик коленного и тазобедренного суставов. В 2019 г. пролечено 6 606 случаев тяжелой ортопедической имплантат-ассоциированной инфекции, в т.ч. 4 282 случая после эндопротезирования коленного и тазобедренного суставов, что составляет 2,91% от первичных эндопротезирований. Заключение. Частота ППИ в РФ коррелирует с мировыми данными. Выявлена высокая сложность маршрутизации пациентов с имплантат-ассоциированной инфекцией и стойкая необходимость в создании федерального центра по лечению имплантат-ассоциированной ортопедической инфекции

Low-energy dynamics of the γγ→ππ\gamma\gamma\to\pi\pi reaction

We calculate the one-quark-loop amplitude for the low energy $\gamma\gamma\to\pi\pi$ collision in the context of the Nambu and Jona-Lasinio model with scalar and pseudoscalar four quark couplings to all orders in the external momenta. We show that the NJL predictions for the $\gamma\gamma\to\pi^+\pi^-$ reaction are not far from the Born amplitude, which is close to the data, and is compatible with the chiral perturbation theory estimations. We determine the corrections given by the NJL model in leading order of $1/N_c$ to the chiral loop amplitude for $\gamma\gamma\to\pi^0\pi^0$. Numerical results for the $\gamma\gamma\rightarrow\pi\pi$ cross sections and for pion polarizabilities are given.Comment: 20 pages in LaTex, 3 figures in 1 Postscript fil

Cosmic ray tests of the D0 preshower detector

The D0 preshower detector consists of scintillator strips with embedded wavelength-shifting fibers, and a readout using Visible Light Photon Counters. The response to minimum ionizing particles has been tested with cosmic ray muons. We report results on the gain calibration and light-yield distributions. The spatial resolution is investigated taking into account the light sharing between strips, the effects of multiple scattering and various systematic uncertainties. The detection efficiency and noise contamination are also investigated.Comment: 27 pages, 24 figures, submitted to NIM

The COMPASS Experiment at CERN

The COMPASS experiment makes use of the CERN SPS high-intensitymuon and hadron beams for the investigation of the nucleon spin structure and the spectroscopy of hadrons. One or more outgoing particles are detected in coincidence with the incoming muon or hadron. A large polarized target inside a superconducting solenoid is used for the measurements with the muon beam. Outgoing particles are detected by a two-stage, large angle and large momentum range spectrometer. The setup is built using several types of tracking detectors, according to the expected incident rate, required space resolution and the solid angle to be covered. Particle identification is achieved using a RICH counter and both hadron and electromagnetic calorimeters. The setup has been successfully operated from 2002 onwards using a muon beam. Data with a hadron beam were also collected in 2004. This article describes the main features and performances of the spectrometer in 2004; a short summary of the 2006 upgrade is also given.Comment: 84 papes, 74 figure

Measurement of (anti)deuteron and (anti)proton production in DIS at HERA

The first observation of (anti)deuterons in deep inelastic scattering at HERA has been made with the ZEUS detector at a centre-of-mass energy of 300--318 GeV using an integrated luminosity of 120 pb-1. The measurement was performed in the central rapidity region for transverse momentum per unit of mass in the range 0.3<p_T/M<0.7. The particle rates have been extracted and interpreted in terms of the coalescence model. The (anti)deuteron production yield is smaller than the (anti)proton yield by approximately three orders of magnitude, consistent with the world measurements.Comment: 26 pages, 9 figures, 5 tables, submitted to Nucl. Phys.

Measurement of the top-quark mass using a leptonic invariant mass in pp collisions at s√ = 13 TeV with the ATLAS detector

A measurement of the top-quark mass (mt) in the tt¯ → lepton + jets channel is presented, with an experimental technique which exploits semileptonic decays of b-hadrons produced in the top-quark decay chain. The distribution of the invariant mass mℓμ of the lepton, ℓ (with ℓ = e, μ), from the W-boson decay and the muon, μ, originating from the b-hadron decay is reconstructed, and a binned-template profile likelihood fit is performed to extract mt. The measurement is based on data corresponding to an integrated luminosity of 36.1 fb−1 of s√ = 13 TeV pp collisions provided by the Large Hadron Collider and recorded by the ATLAS detector. The measured value of the top-quark mass is mt = 174.41 ± 0.39 (stat.) ± 0.66 (syst.) ± 0.25 (recoil) GeV, where the third uncertainty arises from changing the PYTHIA8 parton shower gluon-recoil scheme, used in top-quark decays, to a recently developed setup