15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos1 Sources of atmospheric electron neutrinos A.D. Morozova, S.I.Sinegovsky 15 th Baikal Summer School on Physics of Elementary Particles and Astrophysics Bolshie Koty, 5-12 July 2015

Anna Morozova, Atmospheric neutrinos2 High energy neutrinos High energy neutrinos arise from weak decays of hadrons produced in reactions: Cosmic rays particles interact with matter (stellar wind, supernova remnant and other substance) Cosmic rays interact with matter and electromagnetic fields near remote objects to generate cosmogenic neutrinos; Interactions of cosmic rays with the Earth's atmosphere are the source of the atmospheric neutrinos or with dense electromagnetic fields near the source through the photo-production of pion:

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos3 Astrophysical neutrinos vs. AN background Most of uncertainties in calculations of the high-energy background are due to differences of hadronic interaction models especially as to the strange particles production (and charmed ones as well). The breakthrough in neutrino astrophysics was the detection of 37 high-energy neutrino-induced events with energies 30 TeV – 2 PeV from astrophysical sources in IceCube experiment – 988 days collection data ( ). Atmospheric neutrinos are a background for astrophysical neutrinos which one need know.

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos4 Motivation The atmospheric flux is one order of magnitude less than the muon neutrino flux, that is comparatively low background for astrophysical neutrinos Semileptonic decays of charged and neutral kaons are the main source of as well as is the spring of significant uncertainties of the calculations because of poor studies of the kaon yield at very high energy At energies above 10 TeV the rare decay mode of the short-lived K 0 -meson,, can contribute significantly to the flux (V.Naumov,hep-ph/ ; T. Sinegovskaya, PhD thesis,1999) Besides, pion-induced K-mesons production (usually ignored),, is also of the interest as a contribution to the flux.

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos5 M ethod of the calculation The calculation is performed on the basis of a method of solving equations of hadron-nuclear cascade, which allows one to take into consideration nonpower energy spectrum of cosmic rays, a violation of the Feynman scaling of particle production cross sections, the growth with energy of the total inelastic cross sections for hadron-nucleus collisions V.А. Naumov, T.S. Sinegovskaya, ЯФ 63 (2000) 2020; A.A. Kochanov, T.S. Sinegovskaya, S.I. Sinegovsky, Astropart. Phys. 30 (2008) 219.

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos6 Models for the cosmic rays spectrum In the calculation we used the following the parameterization of the spectrum and composition of CR: ZS – the model by Zatsepin and Sokolskaya, which describes well the data of direct measurements in the experiment ATIC-2 in the range GeV and gives motivated extrapolation to the region of energies up to 100 PeV where spectrum is reconstructed from extensive air shower measurements HGm - a parameterization by Hillas-Gaisser (also account for the knee of the CR spectrum)

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos7 Sources of electron neutrinos Decay mode Branching ratio (%) Critical energy Life time (с) 5,04890 ГэВ 40,55210 ГэВ 0,07120 ТэВ 1001,03 ГэВ

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos8 Относительные вклады источников электронных нейтрино Relative contributions of the decay modes of electron neutrinos flux

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos9 Zenith-angle enhancement of the neutrino fluxes due to switching on the K-sources

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos10 Zenith-angle enhancement of the neutrino fluxes Зенитно-угловое распределение электронных нейтрино для E=10 TeV

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos11 Contribution to flux due to K-mesons produced in interaction Calculated for model HGm+QGSJET-II-03. Energy, GeVθ=90˚θ =0˚ %1 % %5 % %6 %

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos12 Results In this work, we calculated the contributions to the flux of electron neutrinos from the three-particle semileptonic decay modes of charged and neutral K-mesons produced in extensive air showers generated by cosmic rays It is shown that the decay of short-lived neutral kaon at energies above 100 TeV gives more than 1/3 of the total flux of electron neutrinos Account for the production of K-mesons in the pions- nuclei interactions leads to 5-7 % increased flux in the energy range GeV.

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos13 Thank you!

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos14 Backup slides

Atmospheric spectrum and the diffuse flux of cosmic neitrions observed in IceCube experiment 15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos15

Z(E)-factors

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos17 Главное событие в нейтринной астрофизике последних двух лет - детектирование 37 (87) событий от астрофизических нейтрино высоких энергий в эксперименте IceCube ( ожидалось ~ 15 событий от АМ, АН) Атмосферные нейтрино являются фоном к подобным событиям, и его необходимо знать Наибольшая неопределенность расчета фона атмосферных нейтрино при энергиях выше 200 ТэВ обусловлена вкладом процессов рождения и распада странных частиц и очарованных частиц Астрофизические нейтрино и проблема фона атмосферных нейтрино

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos18 Энергетический спектр недавно измерен в эксперименте IceCube в интервале энергий 80 ГэВ - 20 ТэВ Основные источники - распады каонов и мюонов В генерацию потоков при энергиях выше 10 ТэВ может вносить заметный вклад редкая мода распада K 0 -мезонов (до сих пор не была включена в коды МК ) Учет генерации К-мезонов во взаимодействии пионов с ядрами : Постановка задачи

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos19 Target setting (2) Main sources of the atmospheric at high energies are leptonic and semileptonic decays of kaons charged and neutral kaons At energies above 10 TeV the rare decay mode of the short-lived K 0 -meson,, can contribute significantly to the neutrino flux, (Naumov V., Sinegovskaya T. PhD Thesis,1999) (up to now was not taken into account known codes of the Monte Carlo simulation method A contrubution of K-mesons production in the reaction of pion-nuclei interactions

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos20 Метод расчета Расчет выполнен на основе метода решения уравнений адрон-ядерного каскада, который позволяет учитывать нестепенной характер первичного спектра космических лучей, нарушение скейлинга сечений рождения частиц и рост с энергией полных неупругих сечений адрон-ядерных столкновений. Наумов В.А. Синеговская Т.С. Ядерная физика Т. 63. С A.A. Kochanov, T.S. Sinegovskaya, S.I. Sinegovsky, Astropart. Phys. 30, 219 (2008).

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos21 Параметризация спектра космических лучей В расчете использовались следующие параметризации спектра и состава КЛ: ZS – модель В.И.Зацепина и Н.В.Сокольской, хорошо описывает данные прямых измерений в эксперименте ATIC-2 в интервале ГэВ и дает мотивированную экстраполяцию на область энергий до 100 ПэВ (где спектр восстанавливается на основе измеренний широких атмосферных ливней) HGm – параметризация Хилласа-Гайссера (также учитывающая колено спектра КЛ) V.I. Zatsepin, N.V. Sokolskaya, Astronomy & Astrophys. 458, 1 (2006); Astron. Lett. 33, 25 (2007). T. Gaisser, Astropart. Phys. 24, 801 (2012)

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos22 Модели адрон-ядерных взаимодействий при высоких энергиях QGSJET-II-03 (Quark Gluon String model with JETs) - расширение модели кварк-глюонных струн (QGSM), включающее адронные струи - вклад жестких процессов. SIBYLL 2.1, QGSJET описывают взаимодействие кварков и глюонов как рождение одномерных релятивистских струн (трубои цветного тока) с концами, прикрепленными к валентному кварку (дикварку) из мишени и налетающей частицы; когда расстояние между кварками превышает критическое, струна рвется, образуя пару кварк-антикварк

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos23 А. Морозова, Электронные нейтрино23 Вклады каонов в спектры электронных нейтрино

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos24

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos25 Результаты Рассчитаны вклады в потоки электронных нейтрино от трехчастичных полулептонных мод распада заряженных и нейтральных К-мезонов, рождающихся в широких атмосферных ливнях, порожденных космическими лучами Показано, что распад короткоживущего нейтрального каона при энергиях выше 100 ТэВ дает более 1/3 потока атмосферных электронных нейтрино (без учета прямых нейтрино) Учет генерации К-мезонов при взаимодействии пионов с ядрами, приводит к увеличению потока на (5-7) % в интервале энергий ГэВ.

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos26 Адронный каскад в атмосфере

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos27 Регистрация мюонных нейтрино (СС)

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos28 А. Морозова, Электронные нейтрино28 Рассеяние нейтрино на нуклонах Процессы с нейтральными токами (NC): Процессы с заряженными токами (СС):

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos29 ЧастицаВремя жизни(s)Масса(MeV) 493,6 497,6 105,6

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos30 ЧастицаМода распадаВероятность распада(%) Критическая энергия 5,04890 ГэВ 40,55210 ГэВ 0,07120 ТэВ 100 1,03 ГэВ Источники электронных нейтрино

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos31 Энергетические спектры атмосферных и астрофизических нейтрино (иллюстрация)

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos32 Critical energy for a meson decay in the Earth’s atmosphere An illustration

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos33 The energy spectra of atmospheric and astrophysical neutrinos (illustration)

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos34 The contributions of kaon spectra in electron neutrinos

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos35 Motivation (Target setting) Main sources of the atmospheric at high energies is semileptonic decays of kaons charged and neutral kaons At energies above 10 TeV the rare decay mode of the short-lived K 0 -meson,, can contribute significantly to the neutrino flux (V.Naumov,hep-ph/ ; T. Sinegovskaya, PhD thesis,1999) A contrubution of K-mesons production in the reaction of pion-nuclei interactions It is also of the interest how much the reaction of pion- nuclei interactions contrubutes to the flux

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos36 Astrophysical neutrinos and AN background The main event in neutrino astrophysics at last two years is the IceCube detection of 37 high-energy neutrino events from astrophysical sources (expected ~ 15 events from the AM, AN) Atmospheric neutrinos are a background for astrophysical neutrinos which one needs know Most uncertainties in the calculations of the high- energy background are due to difference in hadronic interaction models predictions of the cross sections of the strange particles production

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos37 Motivation Main sources of the atmospheric at high energies are semileptonic decays of kaons charged and neutral kaons At energies above 10 TeV the rare decay mode of the short-lived K 0 -meson,, can contribute significantly to the neutrino flux (V.Naumov,hep-ph/ ; T. Sinegovskaya, PhD thesis,1999) It is also of the interest, how much the pion-nuclei interactions contrbutes to the flux

15th Baikal Summer SchoolAnna Morozova, Atmospheric neutrinos38 Models of hadron-nuclear interactions at high energies QGSJET-II-03 (Quark Gluon String model with JETs) – the extension of the model of quark-gluon strings (MQGS), including hadron jets - the contribution of hard processes. SIBYLL describe the birth of quarks and gluons through a one-dimensional relativistic string (tube current color) with the ends attached to the valence quark (diquark) from the target and incident particle; when the distance between the quarks exceeds a critical value, the string breaks, giving rise to a pair of quark-antiquark. SIBYLL the model with the inclusion of mini-jets (semi- hardd processes) is based on approximates QCD and soft and hard processes