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Author |
Mena, O.; Palomares-Ruiz, S.; Vincent, A.C. |
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Title |
Flavor Composition of the High-Energy Neutrino Events in IceCube |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
113 |
Issue |
9 |
Pages |
091103 - 5pp |
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Abstract |
The IceCube experiment has recently reported the observation of 28 high-energy (> 30 TeV) neutrino events, separated into 21 showers and 7 muon tracks, consistent with an extraterrestrial origin. In this Letter, we compute the compatibility of such an observation with possible combinations of neutrino flavors with relative proportion (alpha(e:)alpha(mu):alpha tau)(circle plus). Although the 7: 21 track-to-shower ratio is naively favored for the canonical (1:1:1)(circle plus) at Earth, this is not true once the atmospheric muon and neutrino backgrounds are properly accounted for. We find that, for an astrophysical neutrino E-2 energy spectrum, (1:1:1)(circle plus). at Earth is disfavored at 81% C. L. If this proportion does not change, 6 more years of data would be needed to exclude (1:1:1)(circle plus) at Earth at 3 sigma C.L. Indeed, with the recently released 3-yr data, that flavor composition is excluded at 92% C. L. The best fit is obtained for (1:0:0)(circle plus). at Earth, which cannot be achieved from any flavor ratio at sources with averaged oscillations during propagation. If confirmed, this result would suggest either a misunderstanding of the expected background events or a misidentification of tracks as showers, or even more compellingly, some exotic physics which deviates from the standard scenario. |
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Address |
[Mena, Olga; Palomares-Ruiz, Sergio; Vincent, Aaron C.] Univ Valencia, CSIC, Inst Fis Corpuscular IFIC, E-46071 Valencia, Spain, Email: omena@ific.uv.es; |
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Amer Physical Soc |
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English |
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ISSN |
0031-9007 |
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Notes |
WOS:000341292800005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
1920 |
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Author |
Palomares-Ruiz, S.; Vincent, A.C.; Mena, O. |
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Title |
Spectral analysis of the high-energy IceCube neutrinos |
Type |
Journal Article |
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Year |
2015 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
91 |
Issue |
10 |
Pages |
103008 - 28pp |
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Abstract |
A full energy and flavor-dependent analysis of the three-year high-energy IceCube neutrino events is presented. By means of multidimensional fits, we derive the current preferred values of the high-energy neutrino flavor ratios, the normalization and spectral index of the astrophysical fluxes, and the expected atmospheric background events, including a prompt component. A crucial assumption resides on the choice of the energy interval used for the analyses, which significantly biases the results. When restricting ourselves to the similar to 30 TeV-3 PeV energy range, which contains all the observed IceCube events, we find that the inclusion of the spectral information improves the fit to the canonical flavor composition at Earth, (1: 1: 1)(circle plus), with respect to a single-energy bin analysis. Increasing both the minimum and the maximum deposited energies has dramatic effects on the reconstructed flavor ratios as well as on the spectral index. Imposing a higher threshold of 60 TeV yields a slightly harder spectrum by allowing a larger muon neutrino component, since above this energy most atmospheric tracklike events are effectively removed. Extending the high-energy cutoff to fully cover the Glashow resonance region leads to a softer spectrum and a preference for tau neutrino dominance, as none of the expected electron (anti) neutrino induced showers have been observed so far. The lack of showers at energies above 2 PeV may point to a broken power-law neutrino spectrum. Future data may confirm or falsify whether the recently discovered high-energy neutrino fluxes and the long-standing detected cosmic rays have a common origin. |
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Address |
[Palomares-Ruiz, Sergio; Mena, Olga] Univ Valencia, CSIC, Inst Fis Corpuscular IFIC, E-46071 Valencia, Spain |
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Publisher |
Amer Physical Soc |
Place of Publication |
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English |
Summary Language |
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Edition |
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ISSN |
1550-7998 |
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Notes |
WOS:000355173100001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2242 |
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Author |
Vincent, A.C.; Palomares-Ruiz, S.; Mena, O. |
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Title |
Analysis of the 4-year IceCube high-energy starting events |
Type |
Journal Article |
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Year |
2016 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
94 |
Issue |
2 |
Pages |
023009 - 18pp |
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Abstract |
After four years of data taking, the IceCube neutrino telescope has detected 54 high-energy starting events (HESE, or contained-vertex events) with deposited energies above 20 TeV. They represent the first detection of high-energy extraterrestrial neutrinos and, therefore, the first step in neutrino astronomy. To study the energy, flavor, and isotropy of the astrophysical neutrino flux arriving at Earth, we perform different analyses of two different deposited energy intervals, [10 TeV-10 PeV] and [60 TeV-10 PeV]. We first consider an isotropic unbroken power-law spectrum and constrain its shape, normalization, and flavor composition. Our results are in agreement with the preliminary IceCube results, although we obtain a slightly softer spectrum. We also find that current data are not sensitive to a possible neutrino-antineutrino asymmetry in the astrophysical flux. Then, we show that although a two-component power-law model leads to a slightly better fit, it does not represent a significant improvement with respect to a single power-law flux. Finally, we analyze the possible existence of a north-south asymmetry, hinted at by the combination of the HESE sample with the throughgoing muon data. If we use only HESE data, the scarce statistics from the Northern Hemisphere does not allow us to reach any conclusive answer, which indicates that the HESE sample alone is not driving the potential north-south asymmetry. |
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Address |
[Vincent, Aaron C.] Univ Durham, Dept Phys, IPPP, Durham DH1 3LE, England, Email: aaron.vincent@durham.ac.uk; |
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Publisher |
Amer Physical Soc |
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English |
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Edition |
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ISSN |
2470-0010 |
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Notes |
WOS:000381492400002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2783 |
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Permanent link to this record |
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Author |
Cline, J.M.; Vincent, A.C. |
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Title |
Cosmological origin of anomalous radio background |
Type |
Journal Article |
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Year |
2013 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
02 |
Issue |
2 |
Pages |
011 - 23pp |
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Keywords |
cosmology of theories beyond the SM; dark matter theory; extragalactic magnetic fields |
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Abstract |
The ARCADE 2 collaboration has reported a significant excess in the isotropic radio background, whose homogeneity cannot be reconciled with clustered sources. This suggests a cosmological origin prior to structure formation. We investigate several potential mechanisms and show that injection of relativistic electrons through late decays of a metastable particle can give rise to the observed excess radio spectrum through synchrotron emission. However, constraints from the cosmic microwave background (CMB) anisotropy, on injection of charged particles and on the primordial magnetic field, present a challenge. The simplest scenario is with a greater than or similar to 9 GeV particle decaying into e(+)e(-) at a redshift of z similar to 5, in a magnetic field of similar to 5 μG, which exceeds the CMB B-field constraints, unless the field was generated after decoupling. Decays into exotic millicharged particles can alleviate this tension, if they emit synchroton radiation in conjunction with a sufficiently large background magnetic field of a dark U(1)' gauge field. |
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Address |
[Cline, James M.] McGill Univ, Dept Phys, Montreal, PQ H3A 2T8, Canada, Email: jcline@physics.mcgill.ca; |
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Publisher |
Iop Publishing Ltd |
Place of Publication |
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English |
Summary Language |
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Original Title |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1475-7516 |
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Notes |
WOS:000315576400011 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1361 |
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Permanent link to this record |
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Author |
Lopez-Honorez, L.; Mena, O.; Palomares-Ruiz, S.; Vincent, A.C. |
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Title |
Constraints on dark matter annihilation from CMB observations before Planck |
Type |
Journal Article |
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Year |
2013 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
07 |
Issue |
7 |
Pages |
046 - 26pp |
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Keywords |
dark matter theory; CMBR theory |
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Abstract |
We compute the bounds on the dark matter (DM) annihilation cross section using the most recent Cosmic Microwave Background measurements from WMAP9, SPT'11 and ACT'10. We consider DM with mass in the MeV-TeV range annihilating 100% into either an e(+)e(-) or a mu(+)mu(-) pair. We consider a realistic energy deposition model, which includes the dependence on the redshift, DM mass and annihilation channel. We exclude the canonical thermal relic abundance cross section (<sigma nu > = 3 x 10(-26) cm(3)s(-1)) for DM masses below 30 GeV and 15 GeV for the e(+)e(-) and mu(+)mu(-) channels, respectively. A priori, DM annihilating in halos could also modify the reionization history of the Universe at late times. We implement a realistic halo model taken from results of state-of-the-art N-body simulations and consider a mixed reionization mechanism, consisting on reionization from DM as well as from first stars. We find that the constraints on DM annihilation remain unchanged, even when large uncertainties on the halo model parameters are considered. |
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Address |
[Lopez-Honorez, Laura] Vrije Univ Brussel, B-1050 Brussels, Belgium, Email: llopezho@vub.ac.be; |
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Corporate Author |
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Thesis |
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Publisher |
Iop Publishing Ltd |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1475-7516 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000322582000047 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1533 |
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Permanent link to this record |