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.
17124386
Exact scale invarianmce of the BF-Yang-Mills theory in three dimensions
The ``extended'' BF-Yang-Mills theory in 3 dimensions, which contains a minimally coupled scalar field, is shown to be ultraviolet finite. It obeys a trivial Callan-Symanzik equation, with all β-functions and anomalous dimensions vanishing. The proof is based on an anomaly-free trace identity valid to all orders of perturbation theory.
119291520
The ultraviolet and infrared perturbative finiteness of massless QED$_3$
The perturbative ﬁniteness is one of the most peculiarproperties of topological ﬁeld theories in three space-time dimensions [1]. Thanks to a by-product of super-renormalizability and the presence of topological terms,Yang-Mills-Chern-SimonsandBF-Yang-Millstheoriesarealso ﬁnite at all orders in perturbation theory—in the senseof a vanishing function [2]. In spite of not being atopological ﬁeld theory, the massless QED
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.
197441123
On the Geometry of Two-Dimensional Anisotropic Non-Linear Sigma Models
119307919
Finite one-loop radiative corrections in the Lorentz- and CPT-violating QED extension
We report on our current progress in the study of finite one-loop radiative corrections in the minimal Lorentz- and CPT-violating QED extension.
55822151
Measurement of geo-neutrinos from 1353 days of Borexino
Abstract We present a measurement of the geo-neutrino signal obtained from 1353 days of data with the Borexino detector at Laboratori Nazionali del Gran Sasso in Italy. With a fiducial exposure of ( 3.69 ± 0.16 ) × 10 31 proton × year after all selection cuts and background subtraction, we detected ( 14.3 ± 4.4 ) geo-neutrino events assuming a fixed chondritic mass Th/U ratio of 3.9. This corresponds to a geo-neutrino signal S geo = ( 38.8 ± 12.0 ) TNU with just a 6 × 10 − 6 probability for a null geo-neutrino measurement. With U and Th left as free parameters in the fit, the relative signals are S Th = ( 10.6 ± 12.7 ) TNU and S U = ( 26.5 ± 19.5 ) TNU . Borexino data alone are compatible with a mantle geo-neutrino signal of ( 15.4 ± 12.3 ) TNU , while a combined analysis with the KamLAND data allows to extract a mantle signal of ( 14.1 ± 8.1 ) TNU . Our measurement of 31.2 − 6.1 + 7.0 reactor anti-neutrino events is in agreement with expectations in the presence of neutrino oscillations.
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.
55022201
Artificial neutrino source experiment in Borexino
An experiment with an artificial neutrino source in Borexino is presented. The neutrino source can be located outside the detector or eventually, at the end of the solar neutrino phase, could be deployed inside. The physics case for the source experiment includes the search for short-baseline neutrino oscillations, neutrino-electron scattering at sub-MeV range, neutrino magnetic moment. Preliminary predictions of the sensitivity are reported for the sterile neutrino search.
8924046
Borexino calibrations: Hardware, Methods, and Results
Borexino was the first experiment to detect solar neutrinos in real-time in the sub-MeV region. In order to achieve high precision in the determination of neutrino rates, the detector design includes an internal and an external calibration system. This paper describes both calibration systems and the calibration campaigns that were carried out in the period between 2008 and 2011. We discuss some of the results and show that the calibration procedures preserved the radiopurity of the scintillator. The calibrations provided a detailed understanding of the detector response and led to a significant reduction of the systematic uncertainties in the Borexino measurements.
11472516
The classification of flaring states of blazars
Aims. The time evolution of the electromagnetic emission from blazars, in particular high-frequency peaked sources (HBLs), displays irregular activity that has not yet been understood. In this work we report a methodology capable of characterizing the time behavior of these variable objects. Methods. The maximum likelihood blocks (MLBs) is a model-independent estimator that subdivides the light curve into time blocks, whose length and amplitude are compatible with states of constant emission rate of the observed source. The MLBs yield the statistical significance in the rate variations and strongly suppresses the noise fluctuations in the light curves. We applied the MLBs for the first time on the long term X-ray light curves (RXTE/ASM) of Mkn 421, Mkn 501, 1ES 1959+650, and 1ES 2155-304, more than 10 years of observational data (1996-2007). Using the MLBs interpretation of RXTE/ASM data, the integrated time flux distribution is determined for each single source considered. We identify in these distributions the characteristic level, as well as the flaring states of the blazars. Results. All the distributions show a significant component at negative flux values, most probably caused by an uncertainty in the background subtraction and by intrinsic fluctuations of RXTE/ASM. This effect concerns in particular short time observations. To quantify the probability that the intrinsic fluctuations give rise to a false identification of a flare, we study a population of very faint sources and their integrated time-flux distribution. We determine duty cycle or fraction of time a source spent in the flaring state of the source Mkn 421, Mkn 501, 1ES 1959+650 and 1ES 2155-304. Moreover, we study the random coincidences between flares and generic sporadic events such as high-energy neutrinos or flares in other wavelengths.