117847403
Resonant neutrino conversion.
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.
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
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.
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.
18145511
On the reduction of Feynman integrals to master integrals
The reduction of Feynman integrals to master integrals is an algebraic problem that requires algorithmic approaches at the modern level of calculations. Straightforward applications of the classical Buchberger algorithm to construct Grobner bases seem to be inefficient. An essential modification designed especially for this problem has been w orked out. It has been already applied in two- and three-loop calculations. We are also suggesting to combine our method with the Laporta’s algorithm.
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.
119205696
Full result for the three-loop static quark potential
The three-loop corrections to the potential of two heavy quarks are computed. Analytic results for the most complicated master integrals are presented.
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.