EditorialNeutrino Physics in the Frontiers of Intensities andVery High Sensitivities
Theocharis Kosmas,1 Hiro Ejiri,2 and Athanasios Hatzikoutelis3
1Division of Theoretical Physics, University of Ioannina, 45110 Ioannina, Greece2Research Center for Nuclear Physics, Osaka University, Osaka 567-0047, Japan3Physics Department, University of Tennessee, Knoxville, TN 37996, USA
Correspondence should be addressed toTheocharis Kosmas; [email protected]
Historically, neutrino physics is a field of continuousadvancement: from the neutrino discovery, proposed by Pauliin order to balance the missing energy of the beta decay inthe early 20th century, to the proof of the neutrino massthrough the measurement of the solar neutrino oscillationsby the end of it. The beginning of the 21st century openedthe intensity frontier with the development of near mega-watt accelerator machines. These machines, competing withthe mega-watt reactors as sources of neutrinos, have beenpushing the frontier back at a rate of 1012 events persecond. So, such experiments are now comparing sensitivityreach in units of “MWatt-kton-years.” Even from the firstdecade of this century, we have already the success of theneutrino oscillationmixing parameters going from unknownquantities to the best measured values in the field.
The sensitivity frontier is characterized by enormousdetector systems that lead precision studies from laboratoryor astrophysical neutrino sources. Relying on the detec-tion sensitivity of these systems, there exist various worksdescribing in high precision the fluxes, rates, distributions,and directions of reactor, beam, and supernova neutrinos.They review a wide range of subjects in accelerator neutrinooscillations at theGeV range, solar and astroneutrinos in sub-MeV to 10MeV, neutrino nuclear interactions in the 10MeVto GeV region, double beta decays, tritium beta decays,and interactions with complex nuclei. The phenomena arewell known, but their absolute cross-sections need to beunderstood at a high precision in order to fix the strong
part of the radiative corrections and be able to independentlycheck the standard model, particularly in the light of the newboson discoveries.The frontiers have generatedmultinationalcollaborations tallying great numbers of scientists and engi-neers having built or designed multimillion projects.
Neutrino oscillation data come from a variety of solar(Super-K, SNO, BOREXINO, etc.), atmospheric (mainlySuper-K), reactor (KamLAND, Double Chooz, RENO, andDaya Bay), and short- and long-baseline accelerator experi-ments (MINOS, MiniBooNE, MINERVA, OPERA, ICAROS,T2K, and NOvA) [1, 2]. They are fed by intense beamsfrom advanced machines at JPARC, CERN, FERMILAB,and ORNL, along with several power plant nuclear reactorsaround the world. To describe them the simplest unitaryform for the lepton mixing matrix is assumed and the state-of-the-art solar and atmospheric neutrino calculations areused. In this special issue, various papers are devoted tothe latest research related to existing experiments as wellas to the sensitivity estimations of future ones like Hyper-Kamiokande, MicroBOONE, DUNE (Deep UndergroundNeutrino Experiment, previously named LBNE), COHER-ENT, JUNO, LENA, and others [1, 3].
In the low-energy and intermediate-energy neutrinorange, the charged-current (CC) and neutral-current (NC)neutrino-nucleus reactions provide crucial understanding ofthe underlying physics of fundamental electroweak inter-actions within and beyond the standard model. Coherentscattering of neutrinos on nuclei was proposed long ago as
Hindawi Publishing CorporationAdvances in High Energy PhysicsVolume 2015, Article ID 806067, 3 pageshttp://dx.doi.org/10.1155/2015/806067
2 Advances in High Energy Physics
an excellent probe of neutral-current ]-nucleus processesfor a plethora of conventional neutrino physics applicationsand new-physics open issues, but it was not yet measuredexperimentally [4]. However, a great number of events areexpected to be recorded in the going experiments (e.g.,COHERENT, TEXONO, and GEMMA). On the theoreticalside, the neutrino-nucleus cross-sections calculations (withnuclear methods like the shell model, quasiparticle random-phase approximation, QRPA, shell-model Monte Carlo, etc.)predict quite reliably the nuclear transitions for neutrinoenergies 𝐸] ≤ 100MeV. Simulated signatures of neutrinointeractions on various isotopes ( 48Ti, 76Ge, 114Cd, 132Xe,etc.) can, subsequently, be derived for several low- andintermediate-energy neutrino distributions of astrophysi-cal neutrino sources, like the solar, supernova, and Earthneutrinos, as well as the laboratory neutrinos, the reactorneutrinos, the pion-muon stopped neutrinos, and the betabeam neutrinos [5–7]. In view of the operation of extremelyintensive neutrino fluxes (at the SNS, PSI, JPARC, Fermilab,etc.), the sensitivity to search for new physics will be largelyincreased, and, therefore, through coherent neutrino-nucleusscattering cross-section measurements, several open ques-tions involving nonstandard neutrino interactions, neutrinomagnetic moment, sterile neutrino searches, and others maybe answered.
Neutrinoless double beta decay (0]𝛽𝛽) is suitable forhigh-sensitivity studies for Majorana ] masses and possi-ble new particles beyond the standard model. The (0]𝛽𝛽)transitions are extremely rare processes of the order of10−34–10−36 per sec. There are several existing (0]𝛽𝛽) exper-
iments in progress as well as R&D on future ones suchas MAJORANA, GERDA, MOON, Super-NEMO, CUORE,SNO+, EXO, KamLAND, COBRA, and NEXT [8]. Thepresent volume includes two (0]𝛽𝛽) papers. One is an inter-esting description of cryogenic multiton scale detectors withscintillation light read-outs. The other is a (0]𝛽𝛽) study usedto search for heavy ] and SUSY particles as a complementaryprobe to the energy frontier searches [8, 9].
During the last few years, there is growing interest inhigh-energy neutrino astronomy including high-energy 𝛾-ray and neutrino astronomy with large neutrino telescopesunder design or construction. New findings have beenreported by ambitious projects in various stages of con-struction including ANTARES, NEMO, NESTOR, IceCube,AUGER, and AMANDA. Novel ideas for neutrino detectionusing acoustic and radio waves continue to receive seriousattention. The relevant topics included in this volume referto solar neutrinos, atmospheric neutrinos, results in high-energy neutrino astronomy, and plans in high-energy neu-trino astronomy and dark matter research. Current experi-ments in the field of high-energy neutrino astronomy includeAMANDA-II and IceCube at the South Pole. Astonishingdevelopments in new telescopes and detector facilities aredescribed for the CTA Cerenkov gamma-ray array, the Fermiorbital telescope, and the aforementioned IceCube neutrinodetector. High-energy neutrinos are assumed to be producedin galactic XRB that include a stellar mass compact objectwith a companion (donor) star still in the main sequence
that is away from the final stages of its evolution [10]. Such abinary system may emit in many different wavelengths, fromradio and IR to high-energy gamma rays and neutrinos. Inthe present volume simulations of neutrino emissions fromrelativistic galactic astrophysical jets are modelled. Theseneutrinos have very high energies (in the order of 100GeV)and specialized instruments are in operation in order todetect them, both on Earth and in space. Furthermore, somenext generation instruments are in the process of design andconstruction.
Neutrino mass may be closely connected to the darkmatter of the Universe. Thus, neutrino oscillations, alongwith neutrino mass generation schemes, suggest dark mattercandidates with properties relevant to direct or indirectdetection prospects. These issues may be closely interlinkedand are several examples of neutrino-motivated dark mattercandidates.Though all of them demonstrate cold dark matterproperties, as far as the cosmic microwave background(CMB) is concerned, some of themmay even behave as warmdarkmatter regarding its structure formation.When it comesto detection, some are ideal for direct detection, while othersare ideal for indirect one through their decay products [11,12]. These searches are presently negative, but they continuefor other phenomena, such as weakly interacting massiveparticles or candidates of cold dark matter. Some of suchdevelopments are in this volume as well.
The knowledge about neutrinos continues to grow usingatmospheric and solar neutrinos, though it is now concen-trating on quantitative and not simply qualitative featuresof understanding the mixing parameters. It is expectedthat further understanding of the nature of neutrino willcome from accelerator neutrinos, using off-axis beams, andreactor neutrinos, usingmultiple detectors underground.Thesensitivity of the current and proposed detecting systems hasspurred the detailed study of neutrino sources, be it man-made or astrophysical. Relying on the detection sensitivityof the intensity and sensitivity frontier systems there arevarious works of high precision estimation of fluxes, rates,and distributions of reactor, beam, and supernova neutrinos.The papers in this special issue are a sample of the world effortto push the frontiers even further back towards the neutrinomass hierarchy and the CP violation of the lepton sector. Theroad to the coveted new physics is now open, but perhaps thiswill be a subject for another special issue.
Theocharis KosmasHiro Ejiri
Athanasios Hatzikoutelis
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