Search for Point-Like Sources of Ultra-High Energy Neutrinos at the Pierre Auger Observatory and Improved Limit on the Diffuse Flux of Tau Neutrinos
Abstract Not Provided
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
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Constraining absolute neutrino masses via detection of galactic supernova neutrinos at JUNO
A high-statistics measurement of the neutrinos from a galactic core-collapse supernova is extremely important for understanding the explosion mechanism, and studying the intrinsic properties of neutrinos themselves. In this paper, we explore the possibility to constrain the absolute scale of neutrino masses m{sub ν} via the detection of galactic supernova neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO) with a 20 kiloton liquid-scintillator detector. In assumption of a nearly-degenerate neutrino mass spectrum and a normal mass ordering, the upper bound on the absolute neutrino mass is found to be m{sub ν}<(0.83±0.24) eV at the 95% confidence level for a typical galactic supernova at a distance of 10 kpc, where the mean value and standard deviation are shown to account for statistical fluctuations. For comparison, we find that the bound in the Super-Kamiokande experiment is m{sub ν}<(0.94±0.28) eV at the same confidence level. However, the upper bound will be relaxed when the model parameters characterizing the time structure of supernova neutrino fluxes are not exactly known, and when the neutrino mass ordering is inverted.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Dark matter vs. neutrinos: the effect of astrophysical uncertainties and timing information on the neutrino floor
Future multi-tonne Direct Detection experiments will be sensitive to solar neutrino induced nuclear recoils which form an irreducible background to light Dark Matter searches. Indeed for masses around 6 GeV the spectra of neutrinos and Dark Matter are so similar that experiments are said to run into a neutrino floor, for which sensitivity increases only marginally with exposure past a certain cross section. In this work we show that this floor can be overcome using the different annual modulation expected from solar neutrinos and Dark Matter. Specifically for cross sections below the neutrino floor the DM signal is observable through a phase shift and a smaller amplitude for the time-dependent event rate. This allows the exclusion power to be improved by up to an order of magnitude for large exposures. In addition we demonstrate that, using only spectral information, the neutrino floor exists over a wider mass range than has been previously shown, since the large uncertainties in the Dark Matter velocity distribution make the signal spectrum harder to distinguish from the neutrino background. However for most velocity distributions it can still be surpassed using timing information, and so the neutrino floor is not an absolute limit on the sensitivity of Direct Detection experiments.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Flavor ratios of extragalactic neutrinos and neutrino shortcuts in extra dimensions
The recent measurement of high energy extragalactic neutrinos by the IceCube Collaboration has opened a new window to probe non-standard neutrino properties. Among other effects, sterile neutrino altered dispersion relations (ADRs) due to shortcuts in an extra dimension can significantly affect astrophysical flavor ratios. We discuss two limiting cases of this effect, first active-sterile neutrino oscillations with a constant ADR potential and second an MSW-like resonant conversion arising from geodesics oscillating around the brane in an asymmetrically warped extra dimension. We demonstrate that the second case has the potential to suppress significantly the flux of specific flavors such as ν{sub μ} or ν{sub τ} at high energies.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Probing nonstandard neutrino cosmology with terrestrial neutrino experiments
Neutrino masses and the number of light neutrino species can be tested in a variety of laboratory experiments and also can be constrained by particle astrophysics and precision cosmology. A conflict between these various results could be an indication of new physics in the neutrino sector. Here, we explore the possibility for reconciliation of otherwise discrepant findings in a simple model containing a light scalar field which produces Mass Varying Neutrinos (MaVaNs). We extend prior work on MaVaNs to consider issues of neutrino clumping, the effects of additional contributions to neutrino mass, and reconciliation of eV mass sterile neutrinos with cosmology.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Radiative model of neutrino mass with neutrino interacting MeV dark matter
We consider the radiative generation of neutrino mass through the interactions of neutrinos with MeV dark matter. We construct a realistic renormalizable model with one scalar doublet (in additional to the standard model doublet) and one complex singlet together with three light singlet Majorana fermions, all transforming under a dark U(1){sub D} symmetry which breaks softly to Z{sub 2}. We study in detail the scalar sector which supports this specific scenario and its rich phenomenology.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Searches for neutrino oscillations in the MiniBooNE experiment: neutrino and antineutrino occurrence analysis of the electron; Búsquedas de oscilaciones de neutrinos en el experimento MiniBooNE: análisis de aparición de neutrinos y antineutrinos del electrón
In this work we implemented the electron neutrino and antineutrino appearance oscillation analyses of the MiniBooNE experiment using the data publicly released by the Collaboration. The calculations were made with algorithms in C++ as well as in graphic processors using CUDA. We performed the analyses corresponding to the publications of 2007 and 2009 in neutrino mode, 2010 in antineutrino mode, and 2013 in neutrino and antineutrino modes, and constructed the confidence intervals in the oscillations parameter space for each case. The contours calculated in this work are indistinguishable from those reported by the MiniBooNE Collaboration when the frequentist corrections of Feldman and Cousins are not taken into account. After implementing these corrections small differences with respect to the official contours appear in the low signal regions, which are ascribed to the fake experiment generation method employed here, and that require further investigation. The best fit probabilities and null point, as the observed event excesses show small variations with respect to those reported in the publications, arising from a difference in the definition of the signal region employed here and forced by the format of the released data, and are consistent within errors. This work was carried out independently to the MiniBooNE Collaboration, and its results are not official. Antes que nada quiero agradecer a mi asesor el Dr. Alexis Aguilar Arévalo, con quien he estado trabajando desde mi servicio social, hace varios años ya. Con él he aprendido una gran variedad de temas: mis primeros programas serios fueron con su guía; principalmente de él adapté mi estilo de redacción de código, me enseñó más física experimental y estadística que lo que aprendí en toda la carrera; formando en mi lo que significa ser un buen experimentalista, mi perspectiva de la física de partículas elementales no podría ser tan amplia como lo es si no fuera por él; enseñándome la historia de los descubrimientos, así como las técnicas experimentales para hacerlos y la teoría que los explica. Mucho trabajo me costó, pero el conocimiento tan amplio que tengo sobre los neutrinos, experimental y teórico, se debe a la enorme paciencia de mi asesor. Mucho le agradezco haberme mandado a Fermilab, en donde fui parte de un activo y amable grupo de trabajo, en donde aprendí una forma distinta de hacer ciencia: mucho más colaborativa. Le agradezco su perfeccionismo y apoyo constante en todos estos años, sin los cuales no hubiera logrado enorgullecerme de esta tesis tanto como lo estoy ahora. Para mi es un rol a seguir, mostrándome la clase de físico en que me quiero convertir. Sobre todo le agradezco su amistad, gracias Alexis.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Neutrino-impact ionization of atoms in searches for neutrino magnetic moment
The ionization of atomic electrons by scattering of neutrinos is revisited. This process is the one studied in the experimental searches for a neutrino magnetic moment using germanium detectors. Current experiments are sensitive to the ionization energy comparable with the atomic energies, and the effects of the electron binding should be taken into account. We find that the so-called stepping approximation to the neutrino-impact ionization is in fact exact in the semiclassical limit and also that the deviations from this approximation are very small already for the lowest bound Coulomb states. We also consider the effects of electron-electron correlations and argue that the resulting corrections to the ionization of independent electrons are quite small. In particular, we estimate that in germanium these are at a 1% level at the energy transfer down to a fraction of keV. Exact sum rules are also presented as well as analytical results for a few lowest hydrogenlike states.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
{sup 11}B and Constraints on Neutrino Oscillations and Spectra from Neutrino Nucleosynthesis
We study the sensitivity to variations in the triple-alpha and {sup 12}C({alpha},{gamma}){sup 16}O reaction rates, of the yield of the neutrino-process isotopes {sup 7}Li, {sup 11}B, {sup 19}F, {sup 138}La, and {sup 180}Ta in core-collapse supernovae. Compared to solar abundances, less than 15% of {sup 7}Li, about 25%-80% of {sup 19}F, and about half of {sup 138}La is produced in these stars. Over a range of {+-}2{sigma} for each helium-burning rate, {sup 11}B is overproduced and the yield varies by an amount larger than the variation caused by the effects of neutrino oscillations. The total {sup 11}B yield, however, may eventually provide constraints on supernova neutrino spectra.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Neutron star kick velocity induced by neutrino chirality flip and a lower bound for the neutrino magnetic moment
We study the neutrino chirality flip during the birth of a neutron star, produced in a core made of strange quark matter. This mechanism is applied to the neutron star kick velocity problem and we show that it is efficient when the neutrino magnetic moment is not smaller than 4.7 × 10 −15 μ B , where μ B is the Bohr magneton. When this lower bound is combined with the most stringent upper bound, our results set a range for the neutrino magnetic moment given by 4.7 × 10 −15 ≤ μ ν / μ B ≤ (0.1 − 0.4) × 10 −11 . The obtained kick velocities for natal conditions are consistent with the observed ones and span the correct range of radii for typical magnetic field intensities.
Ayala, Alejandro↗
Search for Muon Neutrino Disappearance in the Booster Neutrino Beam of Fermilab; Busqueda de Desaparicion de Neutrinos del Muon en el Haz de Neutrinos del Booster de Fermilab
In this work we carried out the disappearance analysis of muon neutrinos produced in the Fermilab Booster Neutrino Beam, using the data released to the public by the collaborations of the MiniBooNE and SciBooNE experiments. The calculations were made with programs in C and C++, implementing the ROOT libraries. From the analysis, using both the classical Pearson method and the Feldman and Cousins frequentist corrections, we obtained the 90\% C.L. limit for the oscillation parameters sin 2 2θ and Δm 2 in the region 0.1 ≤ Δm 2 ≤ 10 eV 2 using a two neutrino model. The result presented in this work is consistent with the official one, with small deviations ascribed to round-off errors in the format of the used data, as well as statistical fluctuations in the generation of fake experiments used in the Feldman and Cousins method. As the official one, our result is consistent with the null oscillation hypothesis. This work was carried out independently to the MiniBooNE and SciBooNE collaborations and its results are not official.
43 PARTICLE ACCELERATORS↗
Neutrino and Anti-neutrino Cross Sections at MiniBooNE
The MiniBooNE experiment has reported a number of high statistics neutrino and anti-neutrino cross sections -among which are the charged current quasi-elastic (CCQE) and neutral current elastic (NCE) neutrino scattering on mineral oil (CH{sub 2}). Recently a study of the neutrino contamination of the anti-neutrino beam has concluded and the analysis of the anti-neutrino CCQE and NCE scattering is ongoing.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
The neutrino signal at HALO: learning about the primary supernova neutrino fluxes and neutrino properties
Core-collapse supernova neutrinos undergo a variety of phenomena when they travel from the high neutrino density region and large matter densities to the Earth. We perform analytical calculations of the supernova neutrino fluxes including collective effects due to the neutrino-neutrino interactions, the Mikheev-Smirnov-Wolfenstein (MSW) effect due to the neutrino interactions with the background matter and decoherence of the wave packets as they propagate in space. We predict the numbers of one- and two-neutron charged and neutral-current electron-neutrino scattering on lead events. We show that, due to the energy thresholds, the ratios of one- to two-neutron events are sensitive to the pinching parameters of neutrino fluxes at the neutrinosphere, almost independently of the presently unknown neutrino properties. Besides, such events have an interesting sensitivity to the spectral split features that depend upon the presence/absence of energy equipartition among neutrino flavors. Our calculations show that a lead-based observatory like the Helium And Lead Observatory (HALO) has the potential to pin down important characteristics of the neutrino fluxes at the neutrinosphere, and provide us with information on the neutrino transport in the supernova core.
79 ASTRONOMY AND ASTROPHYSICS↗
Olber's paradox for superluminal neutrinos: constraining extreme neutrino speeds at TeV–ZeV energies with the diffuse neutrino background
The only invariant speed in special relativity is c; therefore, if some neutrinos travel at even tiny speeds above c, normal special relativity is incomplete and any superluminal speed may be possible. I derive a limit on superluminal neutrino speeds v >> c at high energies by noting that such speeds would increase the size of the neutrino horizon. The increased volume of the Universe visible leads to a brighter astrophysical neutrino background. The nondetection of ''guaranteed'' neutrino backgrounds from star-forming galaxies and ultrahigh energy cosmic rays (UHECRs) constrains v/c at TeV–ZeV energies. I find that v/c∼<820 at 60 TeV from the nondetection of neutrinos from star-forming galaxies. The nondetection of neutrinos from UHECRs constrains v/c to be less than 2500 at 0.1 EeV in a pessimistic model and less than 4.6 at 4 EeV in an optimistic model. The UHECR neutrino background nondetection is strongly inconsistent with a naive quadratic extrapolation of the OPERA results to EeV energies. The limits apply subject to some caveats, particularly that the expected pionic neutrino backgrounds exist and that neutrinos travel faster than c when they pass the detector. They could be improved substantially as the expected neutrino backgrounds are better understood and with new experimental neutrino background limits. I also point out that extremely subluminal speeds would result in a much smaller neutrino background intensity than expected.
79 ASTRONOMY AND ASTROPHYSICS↗
A Measurement of Neutrino Charged Current Interactions and a Search for Muon Neutrino Disappearance with the Fermilab Booster Neutrino Beam
In this thesis, we report on a measurement of muon neutrino inclusive charged current interactions on carbon in the few GeV region, using the Fermilab Booster Neutrino Beam. The all neutrino mode data collected in the SciBooNE experiment is used for this analysis. We collected high-statistics CC interaction sample at SciBooNE, and extracted energy dependent inclusive charged current interaction rates and cross sections for a wide energy range from 0.25 GeV to ~3 GeV. We measure the interaction rates with 6-15% precision, and the cross sections with 10-30% precision. We also made an energy integrated measurements, with the precisions of 3% for the rate, and 8% for the cross section measurements. This is the first measurement of the CC inclusive cross section on carbon around 1 GeV. This inclusive interaction measurement is nearly free from effects of hadron re-interactions in the nucleus. Hence, it is complementary to other exclusive cross section measurements, and essential to understand the neutrino interaction cross sections in the few GeV region, which is relevant to ongoing and future neutrino oscillation experiments. This analysis also provides the normalization for SciBooNE's previous cross section ratio measurements for charged current coherent pion production and neutral current neutral pion production. Then, a precise comparison between our previous measurements and the model predictions becomes possible. The result of the interaction rate measurement is used to constrain the product of the neutrino flux and the cross section at the other experiment on the Fermilab Booster Neutrino Beam: Mini-BooNE. We conducted a search for short-baseline muon neutrino disappearance using data both from SciBooNE and MiniBooNE, to test a possible neutrino oscillation with sterile neutrinos which is suggested by the LSND experiment. With this constraint by SciBooNE, we significantly reduced the flux and the cross section uncertainties at MiniBooNE, and achieved the world best sensitivity for the v μ disappearance at 0.5 < Δm 2 < 30 (eV 2 ). We found no significant oscillation signal, and set one of the world strongest limits for the sterile neutrino models.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Electron-beam energy reconstruction for neutrino oscillation measurements
Neutrinos exist in one of three types or ‘flavours’—electron, muon and tau neutrinos—and oscillate from one flavour to another when propagating through space. This phenomena is one of the few that cannot be described using the standard model of particle physics (reviewed in ref. 1), and so its experimental study can provide new insight into the nature of our Universe (reviewed in ref. 2). Neutrinos oscillate as a function of their propagation distance (L) divided by their energy (E). Therefore, experiments extract oscillation parameters by measuring their energy distribution at different locations. As accelerator-based oscillation experiments cannot directly measure E, the interpretation of these experiments relies heavily on phenomenological models of neutrino–nucleus interactions to infer E. Here we exploit the similarity of electron–nucleus and neutrino–nucleus interactions, and use electron scattering data with known beam energies to test energy reconstruction methods and interaction models. We find that even in simple interactions where no pions are detected, only a small fraction of events reconstruct to the correct incident energy. More importantly, widely used interaction models reproduce the reconstructed energy distribution only qualitatively and the quality of the reproduction varies strongly with beam energy. This shows both the need and the pathway to improve current models to meet the requirements of next-generation, high-precision experiments such as Hyper-Kamiokande (Japan) and DUNE (USA).
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
First Sterile Neutrino Search at NOvA Experiment Using both Neutrino and Anti-Neutrino Data
Neutrinos are among the most abundant fundamental particles in the universe, and yet they are so elusive that they pass through almost everything without leaving a trace. For decades, researchers have measured neutrino oscillations in great detail, refining our understanding of the theories. Yet, once again, neutrino shows their incredibly surprising nature through some recent experimental results, suggesting that our current understanding might be incomplete. Several experiments have observed an unexpected difference in the observed neutrino behaviour from what the Standard Model predicts, showing an excess in some cases (e.g. LSND, MiniBooNE) and a deficit of neutrino events in others (e.g. SAGE, GALLEX). These anomalies challenge our conventional theories of standard three neutrino flavors and phenomenologically motivate the sterile neutrino hypothesis, which does not interact through the usual weak force. While some results appear consistent with this idea, others have found no supporting evidence (e.g. MicroBooNE), leaving the question unanswered. NOvA is one such long-baseline neutrino experiment with its Near Detector (ND) at Fermilab and a Far Detector (FD) at 810 km in Minnesota. It uses the NuMI beam as its primary source of neutrinos for oscillation studies. Its two-detector setup, extended baseline, and ability to conduct combined $\nu$-$\bar\nu$ analyses position it to explore these phenomena in new ways. We use the joint $\nu_{\mu}$ and neutral current (NC) disappearance channels to probe active-sterile mixing in the 3+1 model. This analysis utilizes a data sample of 27$\times$10$^{20}$ protons on target (POT) in neutrino mode and 12.5$\times$10$^{20}$ protons on target (POT) in antineutrino mode. We found no evidence of sterile neutrino at 90$\%$ C.L. We present the limits in $\sin^{2}\theta_{24}$ vs $\Delta m^{2}_{41}$, $\sin^{2}\theta_{34}$ vs $\Delta m^{2}_{41}$, and $\sin^{2}2\theta_{\mu\tau}$ vs $\Delta m^{2}_{41}$ parameter spaces. The limits provided by this analysis are world leading in most of the parameter spaces.
Chaudhary, Shivam [Indian Inst. of Info. Tech. Guw↗
Measurement of the {sup 8}B solar neutrino flux with the KamLAND liquid scintillator detector
We report a measurement of the neutrino-electron elastic scattering rate from {sup 8}B solar neutrinos based on a 123 kton-day exposure of KamLAND. The background-subtracted electron recoil rate, above a 5.5-MeV analysis threshold is 1.49 {+-} 0.14(stat) {+-} 0.17(syst) events per kton-day. Interpreted as due to a pure electron flavor flux with a {sup 8}B neutrino spectrum, this corresponds to a spectrum integrated flux of 2.77 {+-} 0.26(stat) {+-} 0.32(syst) x10{sup 6} cm{sup -2}s{sup -1}. The analysis threshold is driven by {sup 208}Tl present in the liquid scintillator, and the main source of systematic uncertainty is due to background from cosmogenic {sup 11}Be. The measured rate is consistent with existing measurements and with standard solar model predictions which include matter-enhanced neutrino oscillation.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗