118039943
The geometrical phase and resonance conversion of the neutrino spin
125260667
SLIDING SINGLET AND STABILITY OF THE MASS HIERARCHY. (IN RUSSIAN)
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.
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
15962053
Hepp and Speer sectors within modern strategies of sector decomposition
Hepp and Speer sectors were successfully used in the sixties and seventies for proving mathematical theorems on analytically or/and dimensionally regularized and renormalized Feynman integrals at Euclidean external momenta. We describe them within recently developed strategies of introducing iterative sector decompositions. We prove that Speer sectors are reproduced within one of the existing strategies.
15948639
S-bases as a tool to solve reduction problems for Feynman integrals
We suggest a mathematical definition of the notion of master integrals and present a brief review of algorithmic methods to solve reduction problems for Feynman integrals based on integration by parts relations. In particular, we discuss a recently suggested reduction algorithm which uses Grobner bases. New results obtained with its help for a family of three-loop Feynman integrals are outlined.
15376747
ON A POSSIBLE MANIFESTATION OF THE FOUR-COLOR SYMMETRY Z' BOSON IN μ+μ- EVENTS AT THE LHC
The cross section of the μ+μ- pair production in pp-collisions at the LHC is calculated with account of the Z' boson induced by the minimal four-color quark–lepton symmetry (MQLS). The μ+μ- invariant mass spectrum with account of the MQLS Z' boson is analyzed in dependence on the Z' mass. The mass region for the MQLS Z' boson observable at the LHC is found in dependence on the significance and on the integrated luminosity.
2085821
Applying Mellin-Barnes technique and Gröbner bases to the three-loop static potential
The Mellin‐Barnes technique to evaluate master integrals and the algorithm called FIRE to solve IBP relations with the help of Grobner bases are briefly revie wed. In FIRE, an extension of the classical Buchberger algorithm to construct Grobner ba ses is combined with the well-known Laporta algorithm. It is explained how both techniques are used when evaluating the three-loop correction to the static QCD quark potential. First results are presented: the coefficients of n 3 and n 2 , where nl is the number of light 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.