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Register a new userNeutrino Flavor Goniometry by High Energy Astrophysical Beams
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Authors
Sandip Pakvasa
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It is shown how high energy neutrino beams from very distant sources can be utilized to learn about many properties of neutrinos such as lifetimes, mass hierarchy, mixing, minuscule pseudo-Dirac mass splittings; in addition, the production mechanism of neutrinos in astrophysical sources can also be elucidated.
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Analytical formulae for the calculation of secondary particle yields in p-A interactions are given. These formulae can be of great practical importance for fast calculations of neutrino fluxes and for designing new neutrino beam-lines. The formulae are based on a parameterization of the inclusive invariant cross sections for secondary particle production measured in p-Be interactions. Data collected in different energy ranges and kinematic regions are used. The accuracy of the fit to the data with the empirical formulae adopted is within the experimental uncertainties. Prescriptions to extrapolate this parameterization to finite targets and to targets of different materials are given. The results obtained are then used as an input for the simulation of neutrino beams. We show that our approach describes well the main characteristics of measured neutrino spectra at CERN. Thus it may be used in fast simulations aiming at the optimisation of the proposed long-baseline neutrino beams at CERN and FNAL. In particular we will show our predictions for the CNGS beam from CERN to Gran Sasso.
We study the reasonable requirements of two anomalous $U(1)$s in a flavored-axion framework for the anomaly cancellations of both $U(1)$-mixed gravity and $U(1)_Ytimes[U(1)]^2$ which in turn determine the $U(1)_Y$ charges where $U(1)_Y$ is the hypercharge gauge symmetry of the standard model. We argue that, with a flavor symmetry group, axion-induced topology in symmetry-broken phases plays crucial roles in describing how quarks and leptons are organized at a fundamental level and make deep connections with each other. A unified model, as an example, is then proposed in a simple way to describe a whole spectrum of particles where both flavored-axion interactions with normal matter and the masses and mixings of fermions emerge from the spontaneous breaking of a given symmetry group. Once a scale of active neutrino mass defined at a seesaw scale is fixed by the commensurate $U(1)$ flavored-PQ charge of fermions, that of QCD axion decay constant $F_A$ is determined. In turn, fundamental physical parameters complementary to each other are predicted with the help of precision flavor experiments. Model predictions are extracted on the characteristics of neutrino and flavored-axion: $F_A=3.57^{,+1.52}_{,-1.53}times10^{10}$ GeV (consequently, QCD axion mass $m_a=1.52^{+1.14}_{-0.46}times10^{-4}$ eV, axion to photon coupling $|g_{agammagamma}|=2.15^{+1.61}_{-0.64}times10^{-14},text{GeV}^{-1}$, axion to electron coupling $g_{Aee}=3.29^{+2.47}_{-0.98}times10^{-14}$, etc.); atmospheric mixing angle $theta_{23}$, Dirac CP phase $delta_{CP}$, and $0 ubetabeta${it-decay rate} for normal mass ordering and inverted one by taking quantum corrections into account.
The high-energy astrophysical neutrinos recently discovered by IceCube opened a new way to test Lorentz and CPT violation through the astrophysical neutrino mixing properties. The flavor ratio of astrophysical neutrinos is a very powerful tool to investigate tiny effects caused by Lorentz and CPT violation. There are 3 main findings; (1) current limits on Lorentz and CPT violation in neutrino sector are not tight and they allow for any flavor ratios, (2) however, the observable flavor ratio on the Earth is tied with the flavor ratio at production, this means we can test both the presence of new physics and the astrophysical neutrino production mechanism simultaneously, and (3) the astrophysical neutrino flavor ratio is one of the most stringent tests of Lorentz and CPT violation.
In this paper, we propose a hexagonal description for the flavor composition of ultrahigh-energy (UHE) neutrinos and antineutrinos, which will hopefully be determined at the future large neutrino telescopes. With such a geometrical description, we are able to clearly separate the individual flavor composition of neutrinos from that of antineutrinos in one single regular hexagon, which can be regarded as a natural generalization of the widely-used ternary plot. For illustration, we consider the $pp$ or $pgamma$ collisions as the dominant production mechanism for UHE neutrinos and antineutrinos in the cosmic accelerator, and investigate how neutrino oscillations in the standard picture and in the presence of Lindblad decoherence could change the flavor composition of neutrinos and antineutrinos at neutrino telescopes.
We present the reconstruction of neutrino flavor ratios at astrophysical sources. For distinguishing the pion source and the muon-damped source to the 3$sigma$ level, the neutrino flux ratios, $Requivphi( u_mu)/(phi( u_e)+phi( u_tau))$ and $Sequivphi( u_e)/phi( u_tau)$, need to be measured in accuracies better than 10%.
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