55043207
DESIGN OF THE NUCLOTRON BOOSTER IN THE NICA PROJECT
NICA is the new complex being constructed on the JINR aimed to provide collider experiments with ions up to uranium at energy of 3.5x3.5 GeV/u. The NICA layout includes Electron String Ion Source, 6.2 Mev/u linac, 600 MeV/u booster synchrotron, upgraded Nuclotron and ion collider with average luminosity of 10 27 cm -2 s -1 . The main goals of the Booster are the following: accumulation of 4·10 9 Au 32+ ions; acceleration of the heavy ions up to energy required for effective stripping; forming of the required beam emittance with electron cooling system. The present layout makes it possible to place the Booster having 211 m circumference and four fold symmetry lattice inside the yoke of the Synchrophasotron (shut down in 2002). The features of this booster, the requirement to the main synchrotron systems and their parameters are presented in this paper.
5899166
An algorithm to construct Gröbner bases for solving integration by parts relations
This paper is a detailed description of an algorithm based on a generalized Buchberger algorithm for constructing Grobner-type bases associated with polynomials of shift operators. The algorithm is used to calculate Feynman integrals and has proved to be efficient in several complicated cases.
16841546
Three-loop heavy quark potential ¤
We discuss the calculation of the three-loop corrections to the static potential of two heavy quarks.
73596822
Transverse laser cooling by synchro-betatron coupling
Transverse laser cooling with the use of a synchrobetatron coupling is being carried out at S-LSR. Bunched 40 keV Mg beams are cooled by a co-propagating laser with a wavelength of 280 nm. Synchrotron oscillation and horizontal betatron oscillation are coupled by an RF drifttube at a finite dispersive section (D = 1.1 m) in order to transmit longitudinal cooling force to the horizontal degree of freedom. The time evolution of horizontal beam size during laser cooling are measured by a CCD camera. The measured beam size after 35 s is reduced to 0.55 mm on the resonance, compared to 0.85 mm measured or larger at non-resonance conditions. Momentum spreads are 1.7 × 10−4 on the resonance otherwise 1.2 × 10−4. These results indicate that the horizontal heat is connected to the longitudinal direction by the synchro-betatron coupling, which is cooled down by a longitudinal bunched beam laser cooling.
1669343
Applying Gröbner bases to solve reduction problems for Feynman integrals
We describe how Grobner bases can be used to solve the reduction problem for Feynman integrals, i.e. to construct an algorithm that provides the possibility to express a Feynman integral of a given family as a linear combination of some master integrals. Our approach is based on a generalized Buchberger algorithm for constructing Grobner-type bases associated with polynomials of shift operators. We illustrate it through various examples of reduction problems for families of one- and two-loop Feynman integrals. We also solve the reduction problem for a family of integrals contributing to the three-loop static quark potential.
54022118
Phenomenology of maximal and near maximal lepton mixing
ueu,0.3. We show that both probabilities and observables depend on e quadratically when effects are due to vacuum oscillations and they depend on e linearly if matter effects dominate. The most important information on n e mixing comes from solar neutrino experiments. We find that the global analysis of solar neutrino data allows maximal mixing with confidence level better than 99% for 10 28 eV 2 D4s ~99.995% CL! We suggest ways to measure e in future experiments. The observable that is most sensitive to e is the rate @NC#/@CC# in combination with the day-night asymmetry in the SNO detector. With theoretical and statistical uncertainties, the expected accuracy after 5 years is De;0.07. We also discuss the effects of maximal and near-maximal n e mixing in atmospheric neutrinos, supernova neutrinos, and neutrinoless double beta decay.
15323094
Neutrino physics: Open theoretical questions
We know that neutrino mass and mixing provide a window to physics beyond the Standard Model. Now this window is open, at least partly. And the questions are: what do we see, which kind of new physics, and how far "beyond"? I summarize the present knowledge of neutrino mass and mixing, and then formulate the main open questions. Following the bottom-up approach, properties of the neutrino mass matrix are considered. Then different possible ways to uncover the underlying physics are discussed. Some results along the line of seesaw, GUT and SUSY GUT are reviewed.
121199366
On vacuum oscillations solution of the solar neutrino problem
Experimental signatures of vacuum oscillations solution of the solar neutrino problem are considered. This solution predicts a strict correlation between a distortion of the neutrino energy spectrum and an amplitude of seasonal variations of the neutrino flux. The slope parameter which characterizes a distortion of the recoil electron energy spectrum in the Super-Kamiokande experiment and the seasonal asymmetry of the signal have been calculated in a wide range of oscillation parameters. The correlation of the slope and asymmetry gives crucial criteria for identification or exclusion of this solution. For the positive slope indicated by preliminary Super-Kamiokande data we predict (40 – 60) % enhancement of the seasonal variations.
117847403
Resonant neutrino conversion.
119346649
Precise analytical description of the Earth matter effect on oscillations of low energy neutrinos
We present a formalism for the matter effects in the Earth on low energy neutrino fluxes which is both accurate and has all the advantages of a full analytic treatment. The oscillation probabilities are calculated up to the second order term in $ϵ(x)\ensuremath{\equiv}2V(x)E/\ensuremath{\Delta}{m}^{2}$, where $V(x)$ is the neutrino potential at position $x$. We show the absence of large undamped phases which makes the expansion in $ϵ$ well behaved. An improved expansion is presented in terms of the variation of $V(x)$ around a suitable mean value which allows one to treat energies up to those relevant for supernova neutrinos. We discuss also the case of three-neutrino mixing.