123607852
About a possibility of measuring the central temperature of the Sun through the regeneration of the7Be neutrinos in the Earth
The solar neutrino's 7Be line (Eν = 0.862 MeV) has a width of order the temperature in the center of the Sun (~ 1 keV).The regeneration of neutrinos from remote structures of the Earth is suppressed due to the averaging of the effect over the width of the 7Be line (oscillation dying effect). We discuss a possibility of measuring the width of the beryllium line at large liquid scintillator detector (LENA) by measuring the electron neutrino flux at different nadir angles of neutrino trajectories.
59164737
Recent developments in neutrino phenomenology
The first phase of studies of the neutrino mass and mixing is essentially over. The outcome is the discovery of non-zero neutrino mass and determination of the dominant structure of the lepton mixing matrix. In some sense this phase was very simple, and nature was very collaborative with us: Two main effects - the vacuum oscillations and the adiabatic conversion in matter (the MSW-effect) - provide complete interpretation of the experimental results. Furthermore, with the present accuracy of measurements the $3\nu-$mixing analysis is essentially reduced to the $2\nu$ consideration. I will present a concise and comprehensive description of this first phase. The topics include: (i) the concept of neutrino mixing in vacuum and matter; (ii) physics of the oscillations and adiabatic conversion; (iii) the experimental evidences of the flavor transformations and determination of the oscillation parameters. Some implications of the obtained results are discussed. Comments are given on the next phase of the field that will be much more involved.
115887973
Solar neutrinos: Theoretical aspects
18492548
Pontecorvo's original oscillations revisited
Abstract We show that a left-handed neutrino ν L can oscillate into its CPT -conjugate state ν R with maximal amplitude, in direct analogy with K 0 − K 0 oscillations. Peculiarities of such oscillations under different conditions are studied.
119540272
Self-induced spectral splits in supernova neutrino fluxes
In the dense-neutrino region above the neutrino sphere of a supernova (r < or approx. 400 km), neutrino-neutrino refraction causes collective flavor transformations. They can lead to 'spectral splits' where an energy E{sub split} splits the transformed spectrum sharply into parts of almost pure but different flavors. Unless there is an ordinary MSW resonance in the dense-neutrino region, E{sub split} is determined by flavor-lepton number conservation alone. Spectral splits are created by an adiabatic transition between regions of large and small neutrino density. We solve the equations of motion in the adiabatic limit explicitly and provide analytic expressions for a generic example.
31519375
Multiple spectral splits of supernova neutrinos.
Collective oscillations of supernova neutrinos swap the spectra f(nu(e))(E) and f(nu[over ](e))(E) with those of another flavor in certain energy intervals bounded by sharp spectral splits. This phenomenon is far more general than previously appreciated: typically one finds one or more swaps and accompanying splits in the nu and nu[over ] channels for both inverted and normal neutrino mass hierarchies. Depending on an instability condition, swaps develop around spectral crossings (energies where f(nu(e))=f(nu(x)), f(nu[over ](e))=f(nu[over ](x)) as well as E-->infinity where all fluxes vanish), and the widths of swaps are determined by the spectra and fluxes. Washout by multiangle decoherence varies across the spectrum and splits can survive as sharp spectral features.
58945450
Optical measurement of transverse laser cooling with synchro-betatron coupling
Laser cooling experiment of transverse direction for Mg is performed at the small ion storage and cooler ring, S-LSR. We measured horizontal beam size with CCD camera, and longitudinal momentum spread with PAT (Post Acceleration Tube). The measured beam size with CCD camera is decreased from about 1mm to 0.55mm and longitudinal momentum spread measured with PAT increased near the resonant condition. This suggests transverse temperature was transferred to longitudinal direction with synchro-betatron coupling. INTRODUCTION There are several methods to cool ion beam, such as stochastic cooling, electron beam cooling, and laser cooling. Among these methods, laser cooling can achieve the lowest temperature due to its very strong cooling force. The first experiment of laser cooling of ion beam was carried out at TSR [1], and followed at ASTRID [2]. In laser cooling method, a laser is co-propagating or counter-propagating with the ion beam. Since momentum transfer between the laser and the ion beam occurs longitudinally, we can cool the beam particles mainly in the longitudinal direction. Although intra-beam scattering cools the beam transversely, cooling power is weak in usual particle density [3]. Resonant coupling method is proposed to cool ion beam transversely [4]. In the cases betatron tunes (νx, νy) and synchrotron tune νs have the following relations, νs νx = integer νx νy = integer, and there is energy change at a position with a finite dispersion, laser cooling power transmits to transverse direction. In a storage ring, if cooling power is stronger than heating power, beam will be cooled 3-dimensinally. To realize such beam crystallization, the lattice must be properly designed. A small laser-equipped storage ring (SLSR) (Fig. 1) was constructed for this purpose [5]. The principal parameters of S-LSR, the beam and the laser used in the experiment are shown in Table 1.
26897204
Feynman Integral Evaluation by a Sector decomposiTion Approach (FIESTA)
Abstract We present a new program performing the sector decomposition and integrating the expression afterwards. The program takes a set of propagators and a set of indices as input and returns the epsilon-expansion of the corresponding integral. Program summary Program title: FIESTA Catalogue identifier: AECP_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AECP_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GPL v2 No. of lines in distributed program, including test data, etc.: 88 281 No. of bytes in distributed program, including test data, etc.: 6 153 480 Distribution format: tar.gz Programming language: Wolfram Mathematica 6.0 [3] and C Computer: from a desktop PC to supercomputer Operating system: Unix, Linux, Windows RAM: depends on the complexity of the problem Classification: 4.4, 4.12, 5, 6.5 External routines: QLink [1], Vegas [2] Nature of problem: The sector decomposition approach to evaluating Feynman integrals falls apart into the sector decomposition itself, where one has to minimize the number of sectors; the pole resolution and epsilon expansion; and the numerical integration of the resulting expression. Solution method: The sector decomposition is based on a new strategy. The sector decomposition, pole resolution and epsilon-expansion are performed in Wolfram Mathematica 6.0 [3]. The data is stored on hard disk via a special program, QLink [1]. The expression for integration is passed to the C-part of the code, that parses the string and performs the integration by the Vegas algorithm [2]. This part of the evaluation is perfectly parallelized on multi-kernel computers. Restrictions: The complexity of the problem is mostly restricted by the CPU time required to perform the evaluation of the integral, however there is currently a limit of maximum 11 positive indices in the integral; this restriction is to be removed in future versions of the code. Running time: Depends on the complexity of the problem. References: [1] http://qlink08.sourceforge.net , open source. [2] G.P. Lepage, The Cornell preprint CLNS-80/447, 1980. [3] http://www.wolfram.com/products/mathematica/index.html2 .
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.
14044114
Expansion by regions: revealing potential and Glauber regions automatically
When performing asymptotic expansions using the strategy of expansion by regions, it is a non-trivial task to find the relevant regions. The recently published Mathematica code asy.m automates this task, but it has not been able to detect potential regions in threshold expansions or Glauber regions. In this work we present an algorithm and its implementation in the update asy2.m which also reveals potential and Glauber regions automatically.
16841546
Three-loop heavy quark potential ¤
We discuss the calculation of the three-loop corrections to the static potential of two heavy quarks.