76652777
SOX: Short distance neutrino Oscillations with BoreXino
A bstractThe very low radioactive background of the Borexino detector, its large size, and the well proved capability to detect both low energy electron neutrinos and antineutrinos make an ideal case for the study of short distance neutrino oscillations with artificial sources at Gran Sasso.This paper describes the possible layouts of 51Cr (νe) and 144Ce-144Pr $$ \left( {{{\overline{\nu}}_e}} \right) $$ source experiments in Borexino and shows the expected sensitivity to eV mass sterile neutrinos for three possible different phases of the experiment. Expected results on neutrino magnetic moment, electroweak mixing angle, and couplings to axial and vector currents are shown too.
119295910
The first year of Borexino
Borexino is an experiment designed to detect in real-time low energy solar neutrinos. It is installed at the Gran Sasso Underground Laboratory and has started taking data in May 2007. We report the direct measurement of the 7Be solar neutrino signal rate after 1 year of data taking. Implications and perspectives are discussed.
118390776
Final results of Borexino Phase-I on low energy solar neutrino spectroscopy
Borexino has been running since May 2007 at the LNGS with the primary goal of detecting solar neutrinos. The detector, a large, unsegmented liquid scintillator calorimeter characterized by unprecedented low levels of intrinsic radioactivity, is optimized for the study of the lower energy part of the spectrum. During the Phase-I (2007-2010) Borexino first detected and then precisely measured the flux of the 7Be solar neutrinos, ruled out any significant day-night asymmetry of their interaction rate, made the first direct observation of the pep neutrinos, and set the tightest upper limit on the flux of CNO neutrinos. In this paper we discuss the signal signature and provide a comprehensive description of the backgrounds, quantify their event rates, describe the methods for their identification, selection or subtraction, and describe data analysis. Key features are an extensive in situ calibration program using radioactive sources, the detailed modeling of the detector response, the ability to define an innermost fiducial volume with extremely low background via software cuts, and the excellent pulse-shape discrimination capability of the scintillator that allows particle identification. We report a measurement of the annual modulation of the 7 Be neutrino interaction rate. The period, the amplitude, and the phase of the observed modulation are consistent with the solar origin of these events, and the absence of their annual modulation is rejected with higher than 99% C.L. The physics implications of phase-I results in the context of the neutrino oscillation physics and solar models are presented.
121396997
Measurement of CNGS muon neutrino speed with Borexino
Abstract We have measured the speed of muon neutrinos with the Borexino detector using short-bunch CNGS beams. The final result for the difference in time-of-flight between an 〈 E 〉 = 17 GeV muon neutrino and a particle moving at the speed of light in vacuum is δ t = 0.8 ± 0.7 stat ± 2.9 sys ns , well consistent with zero.
121886974
Measurement of the solar 8B neutrino rate with 3 MeV energy threshold in the Borexino detector
Borexino detector, at Gran Sasso Laboratories, measured ν–e elastic scattering from 8B solar neutrinos with 3 MeV energy threshold. We summarize here the results.
205240340
Neutrinos from the primary proton–proton fusion process in the Sun
In the core of the Sun, energy is released through sequences of nuclear reactions that convert hydrogen into helium. The primary reaction is thought to be the fusion of two protons with the emission of a low-energy neutrino. These so-called pp neutrinos constitute nearly the entirety of the solar neutrino flux, vastly outnumbering those emitted in the reactions that follow. Although solar neutrinos from secondary processes have been observed, proving the nuclear origin of the Sun’s energy and contributing to the discovery of neutrino oscillations, those from proton–proton fusion have hitherto eluded direct detection. Here we report spectral observations of pp neutrinos, demonstrating that about 99 per cent of the power of the Sun, 3.84 × 1033 ergs per second, is generated by the proton–proton fusion process.
13873742
A new derivation of the CPT and spin-statistics theorems in noncommutative field theories
We propose an alternative axiomatic description for noncommutative field theories (NCFT) based on some ideas by Soloviev to nonlocal quantum fields. The local commutativity axiom is replaced by the weaker condition that the fields commute at sufficiently large spatial separations, called asymptotic commutativity, formulated in terms of the theory of analytic functionals. The question of a possible violation of the CPT and spin-statistics theorems caused by nonlocality of the commutation relations [xμ,xν]=iθμν is investigated. In spite of this inherent nonlocality, we show that the modification aforementioned is sufficient to ensure the validity of these theorems for NCFT. We restrict ourselves to the simplest model of a scalar field in the case of only space–space noncommutativity.
120792860
Simple parametrizations of light meson properties in hot or dense matter
Abstract Sophisticated calculations of the dynamics of relativistic heavy-ion collisions often need as input properties of light mesons in medium. In this context simple analytical expressions for these quantities which respect chiral symmetry and low-energy current algebra results are most desirable. In the present work we provide such simple expressions based on a bosonized version of the microscopic NJL model. We also study the pion lifetime in hot and dense matter showing that the ratio τ(π − →μ − + ν μ ) τ(π − →e − + ν e ) changes by a factor about three and thus carries a clear signature of the chiral phase transition.
13936057
Microlocal Analysis and Renormalization in Finite Temperature Field Theory
We reassess the problem of renormalization in finite temperature field theory (FTFT). A new point of view elucidates the relation between the ultraviolet divergences for T = 0 and T ¬ = 0 theories and makes clear the reason why the ultraviolet behavior keeps unaffected when we consider the FTFT version associated to a given quantum field theory (QFT). The strength of the derivation one lies on the Hörmander’s criterion for the existence of products of distributions in terms of the wavefront sets of the respective distributions. The approach allows us to regard the FTFT both imaginary and real time formalism at once in a unified way in the contour ordered formalism.
17290178
Scale invariance in a non-Abelian Chern–Simons-matter model
Abstract The general method of reduction in the number of coupling parameters is applied to a Chern–Simons-matter model with several independent couplings. We claim that considering the asymptotic region, and expressing all dimensionless coupling parameters as functions of the Chern–Simons coupling, it is possible to show that all β-functions vanish to any order of the perturbative series. Therefore, the model is asymptotically scale invariant.
119528722
Gauge independence of the effective potential revisited
We apply the formalism of extended BRS symmetry to the investigation of the gauge dependence of the effective potential in a spontaneously symmetry broken gauge theory. This formalism, which includes a set of Grassmann parameters defined as the BRS variations of the gauge-fixing parameters, allows us to derive in a quick and unambiguous way the related Nielsen identities, which express the physical gauge independence, in a class of generalized 't Hooft gauges, of the effective potential. We show in particular that the validity of the Nielsen identities does not require any constraint on the gauge-fixing parameters, contrary to some claims found in the literature. We use the method of algebraic renormalization, which leads to results independent of the particular renormalization scheme used.