The fluorescence detector (FD) of the Pierre Auger Observatory is sensitive to upward-going air showers with energies above 10$^{17}\; \mathrm{eV}$. Given its operation time and wide field of view, the FD has the potential to support or constrain the "anomalous" observations by the ANITA detector, interpreted as upward-going air showers that would be indicative of Beyond Standard Model (BSM) physics. To this end, a search for upward-going air showers with the FD has been performed applying selection criteria that were optimized using 10% of FD data. Dedicated background simulations (downward-going events) have been performed to estimate our capability to distinguish candidates from false positives. Also dedicated signal simulations (upward-going events) have been used to estimate our sensitivity to such showers with a focus on the energy region close to the ANITA observations. Improved and updated results of the Pierre Auger Observatory exposure to upward-going showers will be presented after the unblinding of 14 years of FD data. Extensive simulations allow the FD exposure to be obtained at lower energies which are particularly relevant for the comparison with the ANITA results. A refinement of the method for signal discrimination and background rejection has also been applied. The implications are discussed under the assumption that the ANITA events were due to upward-going events.

Pierre Auger Observatory

SIGNAL (programming language)

10.22323/1.444.1099

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Citations (3)

Nuclear and nucleon transitions of the H dibaryon

Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology (2004)

Glennys R. Farrar G. Zaharijaš

We consider 3 types of processes pertinent to the phenomenology of an H di-baryon: conversion of two $\Lambda$'s in a doubly-strange hypernucleus to an H, decay of the H to two baryons, and -- if the H is light enough -- conversion of two nucleons in a nucleus to an H. We compute the spatial wavefunction overlap using the Isgur-Karl and Bethe-Goldstone wavefunctions, and treat the weak interactions phenomenologically. The observation of $\Lambda$ decays from doubly-strange hypernuclei puts a constraint on the H wavefunction which is plausibly satisfied. In this case the H is very long-lived as we calculate. An absolutely stable H is not excluded at present. SuperK can provide valuable limits.

Hypernucleus

Goldstone

10.1103/physrevd.70.014008

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Citations (19)

Transient Source for the Highest Energy Galactic Cosmic Rays

Proceedings of 36th International Cosmic Ray Conference — PoS(ICRC2019) (2021)

Glennys R. Farrar C. Ding

We show that the dipole anisotropy of CRs above 1 EeV measured by the Pierre Auger Observatory is well described as the sum of the contribution of an extragalactic population of CRs (ECRs) plus CRs from a Galactic source. Above 8 EeV the CRs are almost exclusively extragalactic and the ECR anisotropy is well constrained by data; the energy dependence of the dipole is weak and well-understood theoretically. Modeling the spectrum and composition of CRs above 1 EeV reveals two disjoint rigidity groups, attributable to ECR and GCR populations. This enables the relative contributions of GCRs and ECRs to the total flux in each energy bin to be determined. Thus the ECR dipole in the region containing both ECR and GCRs can be removed, allowing us to isolate the dipole anisotropy of the highest energy Galactic CRs. The dipole of these highest energy GCRs is inconsistent at greater than 6-sigma with being toward or away from the Galactic center, disfavoring acceleration in the Galactic termination shock and preferring acceleration in a transient event whose longitude we constrain: L ~70 \pm 20 deg. The amplitude alpha of the high-energy GCR dipole is ~0.05, which leads to an estimate for the distance/time since the event, using alpha ~ r/(2 c t) ~ 0.05. A candidate remnant of the transient is identified: SNR G65.3+5.7. This SN occurred about 800 pc away, about 20 kyr ago. This single transient event can be responsible for the entire local population of CRs with energies ranging over the bins 0.25-0.5 EeV to 4-8 EeV, with only a tiny fraction of the overall energy of the transient explosion being in VHE CRs. The pulsar PSR J1931+30 may also be a relic of the event; if so, it would confirm the core-collapse nature of the SN. Most massive young stars are in binary systems. We thus propose that the highest energy GCRs were accelerated when the shock created by a core-collapse supernova collided with the wind of its massive binary companion. From the rate of core collapse SNe and the fact that massive stars are generically in binaries with other massive stars, we estimate the probability of seeing an event close enough in space and time to give the observed flux and an anisotropy as large or larger than observed to be O(0.1-1).

Galactic plane

Longitude

10.22323/1.395.0488

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Citations (1)

Monitoring the inter-calibration of the HEAT and Coihueco fluorescence telescopes of the Pierre Auger Observatory with measurements of the brightness of the night sky

Proceedings of 36th International Cosmic Ray Conference — PoS(ICRC2019) (2023)

A. Segreto Adila Abdul Halim P. Abreu M. Aglietta I. Allekotte

The High Elevation Auger Telescopes (HEAT) has increased the Field of View (FoV) of the Fluorescence Detector (FD) at the Coihueco site of the Pierre Auger Observatory and allowed the extension of the energy threshold for the measurements of energies and $X_{\textrm{max}}$ of Extensive Air Showers (EAS) down to $\approx10^{17.2}$ eV. By temporarily orienting HEAT in the downward position, it acquires data in the same FoV as the other Coihueco telescopes, thus providing the opportunity to intercalibrate the detectors by multiple observations of the same EAS. To further control systematic uncertainties in $X_{\textrm{max}}$ and energy measurements, in this contribution we present an innovative method that takes advantage of the Night Sky Brightness (NSB) continuously measured with the FD data acquisition system for monitoring a possible evolution in time of the initial HEAT and Coihueco inter-calibration. While the brightness of the night sky evolves unpredictably and is highly dependent on local weather conditions, we expect to obtain consistent measurements from telescopes located at the same site and observing the same direction of the sky. In this work, we describe the method used to compare the NSB measured by the neighboring HEAT and Coihueco telescopes to monitor the stability of their relative calibration over time. This method allows us to study further the systematics in the inter-calibration of the FD telescopes.

Pierre Auger Observatory

Sky brightness

Night sky

Field of view

10.22323/1.444.0276

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Downward Terrestrial Gamma-ray Flashes at the Pierre Auger Observatory?

Proceedings of 36th International Cosmic Ray Conference — PoS(ICRC2019) (2021)

Roberta Colalillo P. Abreu M. Aglietta Justin M. Albury I. Allekotte

At the Pierre Auger Observatory, designed primarily to study ultra-high-energy cosmic rays, phenomena related to atmospheric electricity are also observed. Particularly, events have been detected with the surface detector, characterized by long-lasting signals (tens of microseconds) and event footprints much larger (up to 200 km$^2$) than those produced by the highest energy cosmic rays. Moreover, some of them appear to be accompanied by smaller events occurring in the same area within about 1 ms and probably produced by the same phenomenon. A previously reported correlation with the World Wide Lightning Location Network, as well as the observation of very low-altitude clouds, confirm that such events are related to thunderstorms. An ad-hoc reconstruction points to high-energy particles being produced very close to the ground, suggesting that they originate from electrons accelerated to relativistic energies in strong electric fields inside low clouds, as is the case for terrestrial gamma-ray flashes above thunderstorms. A clear explanation of the observed phenomenon is hindered by two facts. One is that the rate of such events, detected serendipitously, is very small (less than 2 events/year) and decreases further after optimization of the surface detector trigger for low-energy shower-events. The second is that most events show a puzzling lack of signals in the central part of the footprint. We have studied in detail both effects and will present such studies here. We developed a strategy for a dedicated trigger to enhance the detection efficiency for these events associated with atmospheric-electricity events.

Pierre Auger Observatory

Air shower

Atmospheric electricity

Lightning

10.22323/1.395.0395

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Citations (7)

Wave function of the sexaquark or compact H-dibaryon

Journal of High Energy Physics (2023)

Glennys R. Farrar Nico Wintergerst

A bstract We derive and explicitly display the internal wave function of a color-, flavor- and spin- singlet dibaryon composed of uuddss quarks in a spatially symmetric state, in the approximation of exact SU(3) flavor symmetry. This wavefunction shows that the often-used superposition of ΛΛ, N Ξ and ΣΣ baryons, relevant for di-baryon molecules, accounts for only 1/5 of a spatially symmetric six-quark color-flavor-spin-singlet state, with the remaining 4/5 consisting of products of color-octet baryons. Using the correct wavefunction has important implications for calculations of the mass of the lowest-lying flavor-singlet dibaryon, as we illustrate using the Cornell potential. We also provide a compact representation of the state in terms of creation operators, and comment on the impact of not using the optimal operator in lattice studies of this system.

Octet

Operator (biology)

10.1007/jhep12(2023)099

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Citations (1)

Status and expected performance of the AugerPrime Radio Detector

Proceedings of 36th International Cosmic Ray Conference — PoS(ICRC2019) (2023)

Jannis Pawlowsky Adila Abdul Halim P. Abreu M. Aglietta I. Allekotte

The ongoing AugerPrime upgrade of the Pierre Auger Observatory will yield sensitivity and precision for measuring ultra-high energy (UHE) cosmic rays that are significantly improved over the baseline design. A key part is the installation of the Radio Detector (RD), consisting of loop antennas mounted on top of each of the 1660 water-Cherenkov detectors (WCD). These antennas, with polarizations both parallel and perpendicular to Earth's magnetic field, are sensitive to inclined air showers and will also improve the sky coverage and exposure of the observatory. Of special interest is the great sensitivity to the electromagnetic component of air showers, yielding new information for the reconstruction of the primary mass, energy and arrival direction. Complementing traditional particle detectors like the WCD, the combination of both yields new opportunities to detect rare primary particles, e.g. UHE photons and neutrinos with a large identification probability. Here we present the status and future prospects of the RD. With mass production and deployment ongoing, we show air shower statistics and reconstructions of the already installed detector stations. We detail the layout and integration of the RD, demonstrating the potential of the observatory including radio measurements and RD triggering, especially to detect air showers with weak particle footprints. We show that the new trigger enables the measurement of events for which traditional particle detectors are less sensitive.

Air shower

Upgrade

Pierre Auger Observatory

Cherenkov detector

10.22323/1.444.0344

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Citations (2)

Supersymmetry applied to particle physics — Phenomenological problems

Springer eBooks (2008)

Glennys R. Farrar

Particle (ecology)

10.1007/3-540-12301-6_34

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A precision test of the nature of Dark Matter and a probe of the QCD phase transition

arXiv (Cornell University) (2018)

Glennys R. Farrar

If dark matter (DM) contains equal numbers of u,d,s quarks, the ratio of DM and ordinary matter densities is shown to follow from the Boltzmann distribution in the Quark Gluon Plasma. For sexaquark DM in the 1860-1880 MeV mass range (assuring sexaquark and nuclear stability) and quark masses and transition temperature from lattice QCD, the observed Omega_{DM}/Omega_b = 5.3 is in the predicted range, with <~ 15% uncertainty. The prediction is insensitive to the current form of DM, which could be sexaquarks, strange quark matter nuggets, primordial black holes from their collapse, or a mixture of these.

QCD matter

Strange quark

10.48550/arxiv.1805.03723

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Citations (13)

Zeroing in on the sources of Ultrahigh Energy Cosmic Rays

Chandra Proposal (2008)

Glennys R. Farrar

Source

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