Double Bang Research Articles

Improving the potential of BDF@SPS to search for new physics with liquid argon time projection chambers

Beam dump experiments proposed at the SPS are perfectly suited to explore the parameter space of models with long-lived particles, thanks to the combination of a large intensity with a high proton beam energy. In this paper, we study how the exploration power may be augmented further by installing a detector based on liquid argon time projection chamber technology. In particular, we consider several signatures of new physics particles that may be uniquely searched for with such a detector, including double bang events with heavy neutral leptons, inelastic light dark matter, and millicharged particles.

Heavy neutrino searches through double-bang events at Super-Kamiokande, DUNE, and Hyper-Kamiokande

A variety of new physics scenarios allows for neutrinos to up-scatter into a heavy neutral lepton state. For a range of couplings and neutrino energies, the heavy neutrino may travel some distance before decaying to visible final states. When both the up-scattering and decay occur within the detector volume, these “double bang” events produce distinctive phenomenology with very low background. In this work, we first consider the current sensitivity at Super-Kamiokande via the atmospheric neutrino flux, and find current data may already provide new constraints. We then examine projected future sensitivity at DUNE and Hyper-Kamiokande, including both atmospheric and beam flux contributions to double-bang signals.

Big Bounce or Double Bang? A Reply to Craig and Sinclair on the Interpretation of Bounce Cosmologies

On the orthodox interpretation of bounce cosmologies, a preceding universe was compressed to a small size before ``bouncing'' to form the present expanding universe. William Lane Craig and James Sinclair have argued that the orthodox interpretation is incorrect if the entropy reaches a minimum at the bounce. In their view, the interface between universes represents the birth of two expanding universes, i.e., a ``double bang'' instead of a ``big bounce''. Here, I reply to Craig and Sinclair in defense of the orthodox interpretation. Contrary to their interpretation, features of one universe explain features of the other universe and so must precede the other universe in time. Moreover, contrary to a crucial part of Craig and Sinclair's interpretation, there are bounce cosmologies in which the thermodynamic arrow of time is continuous through the bounce even though the entropy is ``reset'' at the bounce.

Event identification for KM3NeT/ARCA

KM3NeT is a large research infrastructure consisting of a network of deep-sea neutrino telescopes. KM3NeT/ARCA will be the instrument detecting high-energy neutrinos with energies above 100 TeV. This instrument gives a new opportunity to observe the neutrino sky with very high angular resolution to be able to detect neutrino point sources. Furthermore it will be possible to probe the flavour composition of neutrino fluxes, and hence production mechanisms, with so-far unreached precision. Neutrinos produce different event topologies in the detector according to their flavour, interaction channel and deposited energy. Machine-learning algorithms are able to learn features of topologies to discriminate them. In previous analyses only two event types were regarded, namely the shower and track topology. With good timing resolution and precise reconstruction algorithms it is possible to separate into more event types, for example the double bang topology produced by tau neutrinos. The final goal is to distinguish all three neutrino flavors as much as possible. To resolve this issue the KM3NeT collaboration uses deep neural networks trained with Monte Carlo events of all neutrino types. This contribution shows the ability of KM3NeT/ARCA to classify events in more than two neutrino event topologies. Furthermore, the borders between detectable classes are shown, such as the minimum distance the tau has to travel before decaying into a tau neutrino to be detected as double bang event.

Tau Now

Ultra High Energy Cosmic Rays and UHE neutrinos may lead to a new deep astronomy. However the most recent results on their correlations and clustering seem to most authors inconclusive. We briefly remind some UHECR models and past and recent results. Our reading and overlapping of IR-gamma-UHECR maps and their correlations seem to answer to several key puzzles, offering a first hope of the UHECR astronomy, mostly ruled by lightest nuclei from nearby Universe. Regarding the UHE neutrino we recently noted that the flavor ratio and the absence of double bang in IceCube within highest energetic ten events may suggest still a dominant noisy prompt component. However a first correlated UHE crossing muon with expected location (through going upward muon neutrino or horizontally) in IceCube is in our view a milestone in neutrino astronomy road map, possibly partially related, to galactic UHECR narrow clustering. The disturbing and persistent atmospheric neutrino noises, both conventional and prompt, call for a better filtered neutrino astronomy: the tau neutrino ones. There are no yet (at present, detectable) TeV-PeVs or more energetic tau neutrino of atmospheric, conventional or prompt nature; only astrophysical ones might soon shine. Double bangs in IceCube and in particular the tau air-showers in large array are the unique definitive expected signatures of astrophysical signals. In particular tau air-shower amplify in a huge way the otherwise single lepton track, once in decay in flight, into a richest three of secondaries (up to a million of billion Cherenkov photons for PeV tau energy) whose wide areas may extend up to nearly kilometer size. Such airshowers are very directional. PeVs energetic tau lepton penetrate hundreds meters inside the rock before its decay. Therefore horizontal tau air-shower in front of deep, wide valleys or mountain cliff [D. Fargion, A. Aiello, R. Conversano; 26th ICRC, He 6.1.09, 6 p. 396–398. (1999). Ed. D. Kieda, et al. arXiv:astro-ph/9906450], as well as up-going tau air showers escaping our Earth, observable in air by their fluorescence lights as in AUGER and TA, might be a signal at EeVs energies. At lower energies blazing few PeVs tau airshower flashes are better observable from the top of the mountains, by an array located in a crown edge (as water Cherenkov, telescope Cherenkov or radio array), as it has been done in ASHRA or it might be done on ideal modified GRAND experiments constructed within aeolian towers by radio array possibly in mountains, facing the wide peculiar τ neutrino sky: our own Earth.

A discussion of IceCube neutrino events, circa 2015

IceCube has changed the rules of the game and continues to progress. Their observations are compatible with cosmic neutrinos undergoing 3 flavor oscillations. The topologies of the events have been used to probe ordinary and exotic physics. Still, we need independent confirmations of this assumption; the astrophysical connections heavily rely on speculations (excepting special cases, such as GRB); the amount of prompt events is not known precisely; double bang and/or Glashow resonance events are still to be seen; the energy and the angular distributions are not well-known, even if the simplest picture (isotropic flux, power law distributed in energy) is still compatible with the data. In this talk, we select specific topics concerning expectations, inferences and prospects.

Search for Ultra-High Energy Tau Neutrinos in IceCube

The IceCube Neutrino Observatory at the geographic South Pole was designed with the primary goal of discovering high energy neutrinos from astrophysical objects such as active galactic nuclei and gamma ray bursts. IceCube completed construction in 2010 and has been collecting data throughout the construction phase. IceCube is sensitive to all three flavors of neutrinos, each of which has a distinct topological signature within the detector. At sufficiently high energies, the tau neutrino signature is a “double bang” from the charged current interaction of the neutrino and the decay of the tau lepton. At high energies, the tau neutrino has negligible background and would be an intriguing astrophysical signature. A dedicated search for ultra-high energy tau neutrinos (340 TeV–200 PeV) was performed using data from the partial IceCube detector, yielding a 90% CL upper limit of Eν2Φ90(νx)<16.3×10−8GeVcm−2sr−1s−1 on a diffuse astrophysical flux of UHE neutrinos.

What IceCube data tell us about neutrino emission from star-forming galaxies (so far)

Very recently, the IceCube Collaboration reported a flux of neutrinos in the energy range 50 TeV < E_\nu < 2 PeV, which departs from expectations from atmospheric background at the 5.7\sigma level. This flux is in remarkable agreement with the expected diffuse flux of neutrinos from starburst galaxies, and the 3 highest energy events have uncertainty contours encompassing some of such systems. These events, all of which have well-measured energies above 1 PeV, exhibit shower topologies, for which the angular resolution is about 15^\circ. Due to this angular uncertainty and the a posteriori nature of cuts used in our study it is not possible to assign a robust statistical significance to this association. Using muon tracks, which have angular resolution < 1^\circ, we compute the number of observations required to make a statistically significant statement, and show that in a few years of operation the upgraded IceCube detector should be able to confirm or refute this hypothesis. We also note that double bang topology rates constitute a possible discriminator among various astrophysical sources.

TeV sky versus AUGER one: Are UHECR also radioactive, heavy galactic nuclei?

UHECR (Ultra High Cosmic Rays) made by He-like lightest nuclei might solve the AUGER extragalactic clustering along Cen A: He UHECR cannot arrive from Virgo because the light nuclei fragility and opacity above few Mpc; UHECR signals are clustering along Cen-A spreading as observed by horizontal galactic arms magnetic fields, along random vertical angles. Cen A events by He-like spread along a width angle as large as the observed clustered one; such a light nuclei coexist with the Auger heavy nuclei and with the Hires nucleon composition. UHECR He being fragile should partially fragment in secondaries at tens EeV multiplet (D,He3,p) almost as it occurs in the very recent UHECR multiplet at 20EeV along Cen A UHECR clustering. Their narrow crowding within a tiny (Cen A-centric disk) observation area (below 10−2 of the whole AUGER sky) aligned with Cen A may occur by a very low probability, below 3×10−5. Remaining UHECR spread group show correlations with other γ (MeV-Al26 radioactive) maps, mainly due to galactic SNR sources as Vela pulsar, the brightest, nearest GeV source. Other nearest galactic γ sources (as partially Crab and Galactic Center core) show links with UHECR via TeV correlated maps. We speculate here that UHECR are also heavy radioactive galactic nuclei as Ni56, Ni57 and Co57, Co60 widely bent (tens degree up to ≥100°) by galactic fields. UHECR radioactivity (in β and γ channels) and decay in flight at hundreds keV is boosted (by huge Lorentz factor ΓNi≃109−108) leading to TeVs γ correlated sky anisotropy. Tau neutrinos secondaries and their tau airshowers at horizons may rise (from hundreds TeVs–PeVs) in future ICECUBE, ANTARES double bang events, or in ARGO and ASHRA horizons or in AUGER or TA airshowers at PeVs–EeV energies, showing the expected Neutrino astronomy link to UHECR decay in flight.

Tau Neutrinos in IceCube

Tau neutrino detection in IceCube would be strong evidence for the presence of cosmologically-produced neutrinos. In addition to the well-known "double bang" signature, we describe here five additional channels that we believe will not only extend the energy range over which IceCube can be sensitive to tau neutrinos, but also provide useful control over systematic uncertainties via self-consistency checks amongst all detection channels.

A novel tau signature in neutrino telescopes

Kilometer-scale neutrino telescopes will detect muon and electron neutrinos from astrophysical sources at the TeV scale and above. Tau neutrinos are also expected from these sources due to neutrino oscillations over astrophysical baselines. Identification of tau neutrinos is expected to be possible above the PeV energy range through the "double bang" and "lollipop" signatures. We discuss another signature of tau in the PeV-EeV range, arising from the decay of tau leptons inside the detector to much brighter muons.

Astrophysical tau neutrino detection in kilometer-scale Cherenkov detectors via muonic tau decay

Kilometer-scale deep under-ice or -water Cherenkov neutrino detectors may detect muon and electron neutrinos from astrophysical sources at energies of a TeV and above. Tau neutrinos are also expected from these sources due to neutrino flavor oscillations in vacuum, and tau neutrinos are free of atmospheric background at a much lower energy than muon and electron neutrinos. Identification of tau neutrinos is expected to be possible above the PeV energy range through the “double bang” and “lollipop” signatures. We discuss another signature of tau in the PeV–EeV range, arising from the decay of tau leptons inside the detector to much brighter muons.

MICROSCOPIC BLACK HOLE DETECTION IN UHECR: THE DOUBLE BANG SIGNATURE

According to recent conjectures on the existence of large extra dimensions in our universe, black holes could be produced during the interaction of Ultra High Energy Cosmic Rays with the atmosphere. However, and so far, the proposed signatures are based on statistical effects, not allowing identification on an event by event basis, and may lead to large uncertainties. In this note, events with a double bang topology, where the production and instantaneous decay of a microscopic black hole (first bang) is followed, at a measurable distance, by the decay of an energetic tau lepton (second bang) are proposed as an almost background free signature.

Signatures of cosmic tau neutrinos

The importance and signatures of cosmic tau (anti)neutrinos have been studied for upward- and downward-going ${\ensuremath{\mu}}^{\ensuremath{-}}+{\ensuremath{\mu}}^{+}$ and hadronic shower event rates relevant for present and future underground water or ice detectors, utilizing the unique and reliable ultrasmall-$x$ predictions of the dynamical (radiative) parton model. The upward-going ${\ensuremath{\mu}}^{\ensuremath{-}}+{\ensuremath{\mu}}^{+}$ event rates calculated just from cosmic ${\ensuremath{\nu}}_{\ensuremath{\mu}}+{\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$ fluxes are sizably enhanced by taking into account cosmic ${\ensuremath{\nu}}_{\ensuremath{\tau}}+{\overline{\ensuremath{\nu}}}_{\ensuremath{\tau}}$ fluxes and their associated ${\ensuremath{\tau}}^{\ensuremath{-}}+{\ensuremath{\tau}}^{+}$ fluxes as well. The coupled transport equations for the upward-going ${\stackrel{(\ensuremath{-})}{\ensuremath{\nu}}}_{\ensuremath{\tau}}$ flux traversing the Earth imply an enhancement of the attenuated and regenerated ${\stackrel{(\ensuremath{-})}{\ensuremath{\nu}}}_{\ensuremath{\tau}}$ flux typically around ${10}^{4}--{10}^{5}\text{ }\text{ }\mathrm{GeV}$ with respect to the initial cosmic flux. This enhancement turns out to be smaller than obtained so far, in particular, for flatter initial cosmic fluxes behaving like ${E}_{\ensuremath{\nu}}^{\ensuremath{-}1}$. Downward-going ${\ensuremath{\mu}}^{\ensuremath{-}}+{\ensuremath{\mu}}^{+}$ events and, in particular, the background-free and unique hadronic ``double bang'' and ``lollipop'' events allow one to test downward-going cosmic ${\ensuremath{\nu}}_{\ensuremath{\tau}}+{\overline{\ensuremath{\nu}}}_{\ensuremath{\tau}}$ fluxes up to about ${10}^{9}\text{ }\text{ }\mathrm{GeV}$.

Microscopic black hole detection in UHECR: the double bang signature

According to recent conjectures on the existence of large extra dimensions in our universe, black holes could be produced during the interaction of Ultra High Energy Cosmic Rays with the atmosphere. However, and so far, the proposed signatures are based on statistical effects, not allowing identification on an event by event basis, and may lead to large uncertainties. In this note, events with a double bang topology, where the production and instantaneous decay of a microscopic black hole (first bang) is followed, at a measurable distance, by the decay of an energetic tau lepton (second bang) are proposed as an almost background free signature. The characteristics of these events and the capability of large cosmic ray experiments to detect them are discussed.

Propagation of τ-neutrinos and τ-leptons through the Earth and their detection in underwater/ice neutrino telescopes

If muon neutrinos produced in cosmological sources oscillate, neutrino telescopes can have a chance to detect τ-neutrinos. In contrast to ν μs the Earth is completely transparent for ν τs thanks to the short life time of τ-leptons that are produced in ν τ N charged current interactions. τ-lepton decays in flight producing another ν τ (regeneration chain). Thus, ν τs cross the Earth without being absorbed, though loosing energy both in regeneration processes and in neutral current interactions. Neutrinos of all flavors can be detected in deep underwater/ice detectors by means of C̆erenkov light emitted by charged leptons produced in ν interactions. Muon and τ-leptons have different energy loss features, which provide opportunities to identify τ-events among the multitude of muons. Some signatures of τ-leptons that can be firmly established and background free have been proposed in literature, such as `double bang' events. In this paper we present results of Monte Carlo simulations of τ-neutrino propagation through the Earth accounting for neutrino interactions, τ energy losses and τ decays. Parameterizations for hard part and corrections to the soft part of the photonuclear cross-section (which contributes a major part to τ energy losses) are presented. Different methods of τ-lepton identification in large underwater/ice neutrino telescopes are discussed. Finally, we present a calculation of ν τ double bang event rates in km 3 scale detectors.

Future neutrino telescopes

We briefly review the four major high energy neutrino telescopes currently under construction and the motivation for their construction. Progress is such that several instruments with muon detection in the 104 m2 class should be operating in the next several years. Plans are advancing for an international consortium to propose a km3 scale instrument. We highlight a newly identified experiment which may be carried out with such an instrument, if there are substantial numbers of neutrinos in the PeV energy range, as are indeed predicted from some AGN models. The idea is to search for what we call double bang which contain a PeV cascade followed by a charged particle track and then a second and larger cascade separated by about 100 m. This appears to be a nearly background free signature for charged current τ production and decay, and would constitute strong evidence for ντ oscillations, and thus mass. We discuss possible sources of ντ 's, backgrounds for these events, both few, and implications of such detetion.

Somerset bumps

A team from Bristol University has announced that the distinctive noises, locally known as 'Somerset bumps', which have been heard regularly in the South West of England for several months were caused by refraction of Shockwaves from Paris or Heathrow-bound flights of Concorde. An aircraft travelling at supersonic speed has a primary 'boom carpet' where the characteristic 'double bang' will be heard.

The ‘Double Bang’ of Supersonic Aircraft

Two explosive sounds in succession have sometimes been heard when aircraft in the vicinity exceeded the speed of sound. As I am not aware of any discussion of this phenomenon, I wish to direct attention to its explanation.