arXiv subjects

Mauricio Bustamante

Publications and source records attributed to Mauricio Bustamante.

At least 73 records · Page 4Linked to original sources

arXiv2021

PLE$ν$M: A global and distributed monitoring system of high-energy astrophysical neutrinos

High-energy astrophysical neutrinos, discovered by IceCube, are now regularly observed, albeit at a low rate due to their low flux. As a result, open questions about high-energy neutrino astrophysics and particle physics remain limited by statistics at best, or unanswered at worst. Fortunately, this situation will improve soon: in the next few years, a host of new neutrino telescopes, currently under planning and construction, will come online. It is natural to combine their collected observing power: we propose the Planetary Neutrino Monitoring System (PLE$ν$M), a concept for a global repository of high-energy neutrino observations, in order to finally give firm answers to open questions. PLE$ν$M will reach up to four times the exposure available today by combining the exposures of current and future neutrino telescopes distributed around the world -- IceCube, IceCube-Gen2, Baikal-GVD, KM3NeT, and P-ONE. Depending on the declination and spectral index, PLE$ν$M will improve the sensitivity to astrophysical neutrinos by up to two orders of magnitude. We present first estimates on the capability of PLE$ν$M to discover Galactic and extragalactic sources of astrophysical neutrinos and to characterize the diffuse flux of high-energy neutrinos in unprecedented detail.

astro-ph.IM↗

arXiv2021

Flavors of Astrophysical Neutrinos with Active-Sterile Mixing

We revisit the flavor composition of high-energy astrophysical neutrinos observed at neutrino telescopes. Assuming unitary time evolution of the neutrino flavor states, the flavor composition observable at Earth is related to the initial composition at their sources via oscillation-averaged flavor transitions. In a previous study we derived general bounds on the flavor composition of TeV-PeV astrophysical neutrinos assuming three-flavor unitary mixing. We extend these bounds to the case of active-sterile neutrino mixing. Our bounds are analytical, derived based only on the unitarity of the mixing, and do not require sampling over the values of the unknown active-sterile mixing parameters. These bounds apply to any extended active-sterile neutrino mixing scenario where energy-dependent nonstandard flavor mixing dominates over the standard mixing observed in accelerator, reactor, and atmospheric neutrino oscillations.

hep-ph↗

arXiv2021

Core-collapse supernovae stymie secret neutrino interactions

Beyond-the-Standard-Model interactions of neutrinos among themselves -- {\it secret interactions} -- in the supernova core may prevent the shock revival, halting the supernova explosion. Besides, if supernova neutrinos en route to Earth undergo secret interactions with relic neutrinos, the neutrino burst reaching Earth may be down-scattered in energy, falling below the detection threshold. We probe secret neutrino interactions through supernova neutrinos and apply our findings to the supernova SN 1987A. We place the most stringent bounds on flavor-universal secret interactions occurring through a new mediator with mass between 10 MeV and 1 GeV.

astro-ph.HE↗

arXiv2020

The Future of High-Energy Astrophysical Neutrino Flavor Measurements

We critically examine the ability of future neutrino telescopes, including Baikal-GVD, KM3NeT, P-ONE, TAMBO, and IceCube-Gen2, to determine the flavor composition of high-energy astrophysical neutrinos, ie, the relative number of $ν_e$, $ν_μ$, and $ν_τ$, in light of improving measurements of the neutrino mixing parameters. Starting in 2020, we show how measurements by JUNO, DUNE, and Hyper-Kamiokande will affect our ability to determine the regions of flavor composition at Earth that are allowed by neutrino oscillations under different assumptions of the flavor composition that is emitted by the astrophysical sources. From 2020 to 2040, the error on inferring the flavor composition at the source will improve from $> 40\%$ to less than $6\%$. By 2040, under the assumption that pion decay is the principal production mechanism of high-energy astrophysical neutrinos, a sub-dominant mechanism could be constrained to contribute less than 20\% of the flux at 99.7\% credibility. These conclusions are robust in the nonstandard scenario where neutrino mixing is non-unitary, a scenario that is the target of next-generation experiments, in particular the IceCube-Upgrade. Finally, to illustrate the improvement in using flavor composition to test beyond-the-Standard-Model physics, we examine the possibility of neutrino decay and find that, by 2040, combined neutrino telescope measurements will be able to limit the decay rate of the heavier neutrinos to below $1.8\times 10^{-5} (m/\mathrm{eV})$~s$^{-1}$, at 95\% credibility.

hep-ph↗

arXiv2020

Involution on pseudoisotopy spaces and the space of nonnegatively curved metrics

We prove that certain involutions defined by Vogell and Burghelea-Fiedorowicz on the rational algebraic $K$-theory of spaces coincide. This gives a way to compute the positive and negative eigenspaces of the involution on rational homotopy groups of pseudoisotopy spaces from the involution on rational $S^{1}$-equivariant homology group of the free loop space of a simply-connected manifold. As an application, we give explicit dimensions of the open manifolds $V$ that appear in Belegradek-Farrell-Kapovitch's work for which the spaces of complete nonnegatively curved metrics on $V$ have nontrivial rational homotopy groups.

math.GT↗

arXiv2020

Using High-Energy Neutrinos As Cosmic Magnetometers

Magnetic fields are crucial in shaping the non-thermal emission of the TeV-PeV neutrinos of astrophysical origin seen by the IceCube neutrino telescope. The sources of these neutrinos are unknown, but if they harbor a strong magnetic field, then the synchrotron energy losses of the neutrino parent particles---protons, pions, and muons---leave characteristic imprints on the neutrino energy distribution and its flavor composition. We use high-energy neutrinos as "cosmic magnetometers" to constrain the identity of their sources by placing limits on the strength of the magnetic field in them. We look for evidence of synchrotron losses in public IceCube data: 6 years of High Energy Starting Events (HESE) and 2 years of Medium Energy Starting Events (MESE). In the absence of evidence, we place an upper limit of 10 kG-10 MG (95% C.L.) on the average magnetic field strength of the sources.

astro-ph.HE↗

arXiv2020

Bounds on secret neutrino interactions from high-energy astrophysical neutrinos

Neutrinos offer a window to physics beyond the Standard Model. In particular, high-energy astrophysical neutrinos, with TeV-PeV energies, may provide evidence of new, "secret" neutrino-neutrino interactions that are stronger than ordinary weak interactions. During their propagation over cosmological distances, high-energy neutrinos could interact with the cosmic neutrino background via secret interactions, developing characteristic energy-dependent features in their observed energy distribution. For the first time, we look for signatures of secret neutrino interactions in the diffuse flux of high-energy astrophysical neutrinos, using 6 years of publicly available IceCube High Energy Starting Events (HESE). We find no significant evidence for secret neutrino interactions, but place competitive upper limits on the coupling strength of the new mediator through which they occur, in the mediator mass range of 1-100 MeV.

astro-ph.HE↗

arXiv2020

New limits on neutrino decay from the Glashow resonance of high-energy cosmic neutrinos

Discovering neutrino decay would be strong evidence of physics beyond the Standard Model. Presently, there are only lax lower limits on the lifetime $τ$ of neutrinos, of $τ/m \sim 10^{-3}$ s eV$^{-1}$ or worse, where $m$ is the unknown neutrino mass. High-energy cosmic neutrinos, with TeV-PeV energies, offer superior sensitivity to decay due to their cosmological-scale baselines. To tap into it, we employ a promising method, recently proposed, that uses the Glashow resonance $\barν_e + e \to W$, triggered by $\barν_e$ of 6.3 PeV, to test decay with only a handful of detected events. If most of the $ν_1$ and $ν_2$ decay into $ν_3$ en route to Earth, no Glashow resonance would occur in neutrino telescopes, because the remaining $ν_3$ have only a tiny electron-flavor content. We turn this around and use the recent first detection of a Glashow resonance candidate in IceCube to place new lower limits on the lifetimes of $ν_1$ and $ν_2$. For $ν_2$, our limit is the current best. For $ν_1$, our limit is close to the current best and, with the imminent detection of a second Glashow resonance, will vastly surpass it.

astro-ph.HE↗

arXiv2020

An Andean Deep-Valley Detector for High-Energy Tau Neutrinos

High-energy astrophysical neutrinos, recently discovered by IceCube up to energies of several PeV, opened a new window to the high-energy Universe. Yet much remains to be known. IceCube has excellent muon flavor identification, but tau flavor identification is challenging. This limits its ability to probe neutrino physics and astrophysics. To address this limitation, we present a concept for a large-scale observatory of astrophysical tau neutrinos in the 1-100 PeV range, where a flux is guaranteed to exist. Its detection would allow us to characterize the neutrino sources observed by IceCube, to discover new ones, and test neutrino physics at high energies. The deep-valley air-shower array concept that we present provides highly background-suppressed neutrino detection with pointing resolution <1 degree, allowing us to begin the era of high-energy tau-neutrino astronomy.

astro-ph.IM↗

arXiv2019

Fundamental physics with high-energy cosmic neutrinos today and in the future

The astrophysical neutrinos discovered by IceCube have the highest detected neutrino energies --- from TeV to PeV --- and likely travel the longest distances --- up to a few Gpc, the size of the observable Universe. These features make them naturally attractive probes of fundamental particle-physics properties, possibly tiny in size, at energy scales unreachable by any other means. The decades before the IceCube discovery saw many proposals of particle-physics studies in this direction. Today, those proposals have become a reality, in spite of astrophysical unknowns. We will showcase examples of doing fundamental neutrino physics at these scales, including some of the most stringent tests of physics beyond the Standard Model. In the future, larger neutrino energies --- up to tens of EeV --- could be observed with larger detectors and further our reach.

astro-ph.HE↗

arXiv2019

The Giant Radio Array for Neutrino Detection (GRAND): Science and Design

The Giant Radio Array for Neutrino Detection (GRAND) is a planned large-scale observatory of ultra-high-energy (UHE) cosmic particles, with energies exceeding 10^8 GeV. Its goal is to solve the long-standing mystery of the origin of UHE cosmic rays. To do this, GRAND will detect an unprecedented number of UHE cosmic rays and search for the undiscovered UHE neutrinos and gamma rays associated to them with unmatched sensitivity. GRAND will use large arrays of antennas to detect the radio emission coming from extensive air showers initiated by UHE particles in the atmosphere. Its design is modular: 20 separate, independent sub-arrays, each of 10 000 radio antennas deployed over 10 000 km^2. A staged construction plan will validate key detection techniques while achieving important science goals early. Here we present the science goals, detection strategy, preliminary design, performance goals, and construction plans for GRAND.

astro-ph.HE↗

arXiv2019

Astrophysics Uniquely Enabled by Observations of High-Energy Cosmic Neutrinos

High-energy cosmic neutrinos carry unique information about the most energetic non-thermal sources in the Universe. This white paper describes the outstanding astrophysics questions that neutrino astronomy can address in the coming decade. A companion white paper discusses how the observation of cosmic neutrinos can address open questions in fundamental physics. Detailed measurements of the diffuse neutrino flux, measurements of neutrinos from point sources, and multi-messenger observations with neutrinos will enable the discovery and characterization of the most energetic sources in the Universe.

astro-ph.HE↗

arXiv2019

Fundamental Physics with High-Energy Cosmic Neutrinos

High-energy cosmic neutrinos can reveal new fundamental particles and interactions, probing energy and distance scales far exceeding those accessible in the laboratory. This white paper describes the outstanding particle physics questions that high-energy cosmic neutrinos can address in the coming decade. A companion white paper discusses how the observation of cosmic neutrinos can address open questions in astrophysics. Tests of fundamental physics using high-energy cosmic neutrinos will be enabled by detailed measurements of their energy spectrum, arrival directions, flavor composition, and timing.

astro-ph.HE↗

arXiv2019

Inferring the flavor of high-energy astrophysical neutrinos at their sources

The sources and production mechanisms of high-energy astrophysical neutrinos are largely unknown. A promising opportunity for progress lies in the study of neutrino flavor composition, i.e., the proportion of each flavor in the flux of neutrinos, which reflects the physical conditions at the sources. To seize it, we introduce a Bayesian method that infers the flavor composition at the neutrino sources based on the flavor composition measured at Earth. We find that present data from the IceCube neutrino telescope favor neutrino production via the decay of high-energy pions and rule out production via the decay of neutrons. In the future, improved measurements of flavor composition and mixing parameters may single out the production mechanism with high significance.

astro-ph.HE↗

arXiv2019

Pushing the Energy and Cosmic Frontiers with High-Energy Astrophysical Neutrinos

The astrophysical neutrinos recently discovered by the IceCube neutrino telescope have the highest detected neutrino energies --- from TeV to PeV --- and travel the longest distances --- up to a few Gpc, the size of the observable Universe. These features make them naturally attractive probes of fundamental particle-physics properties, possibly tiny in size, at energy scales unreachable by any other means. The decades before the IceCube discovery saw many proposals of particle-physics studies in this direction. Today, those proposals have become a reality, in spite of prevalent astrophysical unknowns. We showcase examples of studying fundamental neutrino physics at these scales, including some of the most stringent tests of physics beyond the Standard Model.

astro-ph.HE↗

arXiv2019

Negatively curved bundles in the Igusa stable range

We use classical results in smoothing theory to extract information about the rational homotopy groups of the space of negatively curved metrics on a high dimensional manifold. It is also shown that smooth M-bundles over spheres equipped with fiberwise negatively curved metrics, represent elements of finite order in the homotopy groups of the classifying space for smooth M-bundles, provided the dimension of M is large enough.

math.GT↗

arXiv2019

Echo Technique to Distinguish Flavors of Astrophysical Neutrinos

The flavor composition of high-energy astrophysical neutrinos is a rich observable. However, present analyses cannot effectively distinguish particle showers induced by $ν_e$ versus $ν_τ$. We show that this can be accomplished by measuring the intensities of the delayed, collective light emission from muon decays and neutron captures, which are, on average, greater for $ν_τ$ than for $ν_e$. This new technique would significantly improve tests of the nature of astrophysical sources and of neutrino properties. We discuss the promising prospects for implementing it in IceCube and other detectors.

astro-ph.HE↗

arXiv2019

Open Questions in Cosmic-Ray Research at Ultrahigh Energies

We review open questions and prospects for progress in ultrahigh-energy cosmic ray (UHECR) research, based on a series of discussions that took place during the `The High-Energy Universe: Gamma-Ray, Neutrino, and Cosmic-ray Astronomy' MIAPP workshop in 2018. Specifically, we overview open questions on the origin of the bulk of UHECRs, the UHECR mass composition, the origin of the end of the cosmic-ray spectrum, the transition from Galactic to extragalactic cosmic rays, the effect of magnetic fields on the trajectories of UHECRs, anisotropy expectations for specific astrophysical scenarios, hadronic interactions, and prospects for discovering neutral particles as well as new physics at ultrahigh energies. We also briefly present upcoming and proposed UHECR experiments and discuss their projected science reach.

astro-ph.HE↗