D. Naumov

Longitudinal polarisation of Λ and Λ̄ hyperons in lepton–nucleon deep-inelastic scattering

We consider models for the spin transfers to Λ and Λ̄ hyperons produced in lepton–nucleon deep-inelastic scattering. We make predictions for longitudinal Λ and Λ̄ spin transfers for the COMPASS experiment and for HERA, and for the spin transfer to Λ hyperons produced at JLAB. We demonstrate that accurate measurements of the spin transfers to Λ and Λ̄ hyperons with COMPASS kinematics have the potential to probe the intrinsic strangeness in the nucleon. We show that a measurement of Λ̄ polarisation could provide a clean probe of the spin transfer from s̄ quarks and provides a new possibility to measure the antistrange quark distribution function. COMPASS data in a domain of x that has not been studied previously will provide valuable extra information to fix models for the nucleon spin structure. The spin transfer to Λ̄ hyperons, which could be measured by the COMPASS experiment, would provide a new tool to distinguish between the SU(6) and Burkardt–Jaffe (BJ) models for baryon spin structure. In the case of the HERA electron–proton collider experiments with longitudinally-polarised electrons, the separation between the target and current fragmentation mechanisms is more clear. It provides a complementary probe of the strange quark distribution and helps distinguish between the SU(6) and BJ models for the Λ and Λ̄ spin structure. Finally, we show that the spin transfer to Λ hyperons measured in a JLAB experiment would be dominated by the spin transfer of the intrinsic polarised-strangeness in the remnant nucleon, providing an independent way to check our model predictions.

Introduction to Neutrino Physics

A synopsis of lectures is presented which were delivered by the author in 2010 at the Baikal summer school on physics of elementary particles and astrophysics. The lectures are primarily intended for students, postgraduates, and young researchers as an introductory course on neutrino physics.

PREPARATION OF THE TUS SPACE EXPERIMENT FOR UHECR STUDY

We report on the current status of the TUS space mission project: its goals and the progress achieved so far. The Fresnel mirrors design, performed checks and their production are discussed. Also we discuss our future plans including auxiliary analysis of the fluorescence light yield measured this year by LAPP (Annecy), JINR (Dubna) and LIP (Lisbon) MACFLY Collaboration.

CUDA Support in GNA Data Analysis Framework

Usage of GPUs as co-processors is a well-established approach to accelerate costly algorithms operating on matrices and vectors. We aim to further improve the performance of the Global Neutrino Analysis framework (GNA) by adding GPU support in a way that is transparent to the end user. To achieve our goal we use CUDA, a state of the art technology providing GPGPU programming methods. In this paper we describe new features of GNA related to CUDA support. Some specific framework features that influence GPGPU integration are also explained. The paper investigates the feasibility of GPU technology application and shows an example of the achieved acceleration of an algorithm implemented within framework. Benchmarks show a significant performance increase when using GPU transformations. The project is currently in the developmental phase. Our plans include implementation of the set of transformations necessary for the data analysis in the GNA framework and tests of the GPU expediency in the complete analysis chain.

Quantum field theoretical description of neutrino oscillations and reactor antineutrino anomaly

We suggest a possible explanation of the reactor antineutrino anomaly derived from a covariant quantum field-theoretical approach to neutrino oscillations. Some disadvantages of the currently prevailing interpretation of the anomaly, based upon the sterile neutrino hypothesis are pointed out.

Inverse-square law violation and reactor antineutrino anomaly

We discuss a possibility that the so-called reactor antineutrino anomaly can be, at least in part, explained by applying a quantum field-theoretical approach to neutrino oscillations, which in particular predicts a small deviation from the classical inverse-square law at short but macroscopic distances between the neutrino source and detector. An extensive statistical analysis of the reactor data is performed to examine this speculation.

A multiple production study of neutral strange particles in νμ CC interactions in the NOMAD experiment

A multiple production study of neutral strange particles in νμ charged current interactions has been performed using the full data sample from the NOMAD experiment. This analysis allows one to investigate the mechanisms of strange particle production in neutrino interactions. In this study we have tried to build a model for the production of strange particles, which would allow us to describe our measured rates of neutral strange particles, as well as the rates of the single-, double-and triple-V 0 production: Λ, K 0, \(\bar \Lambda \), K 0 K 0, ΛK 0, Λ\(\bar \Lambda \), K 0 \(\bar \Lambda \), ΛΛ, and K 0 K 0 K 0.