Neutrino Astrophysics

Neutrino Astrophysics Ryan Nichol UK Input to European Strategy Neutrino Astrophysics Ryan Nichol UK Input to European Strategy Highly cited papers • Higgs Discovery (2012) • Z discovery (1983) –1500+ – 8000+ citations –2000+ • SN1987a neutrinos (1987) • Atmospheric neutrino • Positron excess –1500+ oscillations (1998) [PAMELA] (2008) • Weak neutral current –5000+ citations –1900+ (1973) • Top quark discovery • Reactor neutrino theta_13 –1500+ (1995) (2012) • Charmomium (2003) –3000+ citations –1900+ –1400+ • Solar neutrino oscillations • b-quark discovery (1977) • B-Bbar oscillation (1987) (2002) –1900+ –1300+ –3000+ citations • W-discovery (1983) • nu_mu -> nu_e (2011) • Kaon CP violations (1964) –1800+ –1300+ –3000+ citations • Z width (2005) • Accelerator neutrino • Reactor antineutrino –1700+ oscillation (2002) [KamLAND] (2003) • Proton spin crisis (1989) –1100+ –2000+ citations –1700+ • Muon neutrino discovery • Gravitational Waves • LSND anomaly (2001) (1962) (2016) –1700+ –1100+ –2000+ citations • Parity non conservation • DAMA/Libra (2008-) • c-quark discovery (1974) (1957) –1000+ –2000+ citations –1600+ • Pentaquark [LEPS] (2003) • Solar neutrino • LUX Dark Matter (2013) –1000+ [Homestake] (1968-1998) –1500+ • Neutron EDM (2006) !3 –2000+ • g-2 (2006) –1000+ Highly cited papers • Higgs Discovery (2012) • Z discovery (1983) –1500+ – 8000+ citations –2000+ • SN1987a neutrinos (1987) • Atmospheric neutrino • Positron excess –1500+ oscillations (1998) [PAMELA] (2008) • Weak neutral current –5000+ citations –1900+ (1973) • Top quark discovery • Reactor neutrino theta_13 –1500+ (1995) (2012) • Charmomium (2003) –3000+ citations –1900+ –1400+ • Solar neutrino oscillations • b-quark discovery (1977) • B-Bbar oscillation (1987) (2002) –1900+ –1300+ –3000+ citations • W-discovery (1983) • nu_mu -> nu_e (2011) • Kaon CP violations (1964) –1800+ –1300+ –3000+ citations • Z width (2005) • Accelerator neutrino • Reactor antineutrino –1700+ oscillation (2002) [KamLAND] (2003) • Proton spin crisis (1989) –1100+ –2000+ citations –1700+ • Muon neutrino discovery • Gravitational Waves • LSND anomaly (2001) (1962) (2016) –1700+ –1100+ –2000+ citations • Parity non conservation • DAMA/Libra (2008-) • c-quark discovery (1974) (1957) –1000+ –2000+ citations –1600+ • Pentaquark [LEPS] (2003) • Solar neutrino • LUX Dark Matter (2013) –1000+ [Homestake] (1968-1998) –1500+ • Neutron EDM (2006) !4 –2000+ • g-2 (2006) –1000+ Big Picture (from Johannes Blümer) !5 Neutrino Universe !6 arXiv:1111.0507 Tritium β-decay and Neutrino Capture Neutrino capture on Tritium Tritium β-decay (12.3 yr half-life) PTOLEMY, Chris Tully !7 https://indico.cern.ch/event/640340 5 Neutrino Universe !8 arXiv:1111.0507 UK perspective SolarFuture prospectsNeutrinos 22 SJM Peeters, UK Input to the European Particle Physics Strategy Update, Durham, 2018.04.14 !9 Neutrino Universe !10 arXiv:1111.0507 Aside: Super Nova Neutrinos • SN1987A –24 neutrino events detected by Kamikande-II, IMB and Baksan –Learned about • Supernova collapse mechanisms • Neutrinos feel gravity (similarly to photons) Kamikande-II SN1987A citations • Neutrino mass < 23eV from per year from INSPIRE-HEP time of flight dispersion • Neutrinos are not charged • Limits on non-neutrino weakly interacting particles • Axion bounds • Neutrino mixing and oscillations • Exotic neutrino disappearance!11 * before 2011, excluding solar Neutrino Universe !12 arXiv:1111.0507 Atmospheric Neutrinos 13 300 BG after fit Tau after fit 1000 Data 800 200 600 Events 400 100 Oscillations 200 Tau-like Upward 0 0 14 Accepted by PRL -1 -0.5 0 0.5 1 0 0.2 0.4 0.6 0.8 1 1200 a measurement of the cross section. The DONUT mea- termined600 by Super-K atmospheric1000 neutrinos is found to 38 2 800 surement was based on 9 observed charged-current tau be (0.40400 0.08) 10− cm by scaling the measured cross ± ⇥ 600 neutrino events with an estimated background of 1.5 sectionEvents in Eqn. 9 by 41%. This resulting DIS-only cross- events. In DONUT, 800 GeV protons from the Fermilab section200 is comparable and consistent400 with the DONUT 200 Tevatron were used to produce neutrino beam by collid- measurement ofNon the tau-like DIS ⌫⌧ cross section extrapolatedDownward to 0 0 ing with a beam dump, and tau neutrinos were produced lower neutrino-1 -0.5 energy.0 0.5 1 0 0.2 0.4 0.6 0.8 1 NN output via decays of charm mesons. The mean energy of the de- CosΘ tected tau neutrino interactions was estimated to be 111FIG. 14. Fit results, assuming the normal hierarchy, showing binned projections in the NN output and zenith angle distribution for tau-like (NN > 0.5), upward-going [cos ⇥ < 0.2], non-tau-like (NN < 0.5) and downward-going [cos ⇥ > 0.2] events for ) − GeV, an energy at which deep inelastic interactions areboth the two-dimensional2 PDFs and data. The PDFs and data sets have been combined from SK-I through SK-IV. The fitted tau signal is shown in gray. dominant. Assuming that the DIS charged-current tau cm 10 neutrino cross section had a linear dependence on neu- -38 than 3.5 GeV in the CC ⌫⌧ interactions because of the ) trino energy, DONUT measured the energy-independentenergy threshold, and the expectation of CC ⌫⌧ interac- 2 tions with more than1 70 GeV is less than one in the entire cm slope of the cross section, σconst, after correcting for the -38 10 10 run period. kinematic e↵ect of tau lepton mass from the standard The flux-averaged theoretical charged-current tau neu- 38 2 1 1 Events per Bin trino cross section is calculated to be 0.64 10− cm model calculation: -1 10 NEUT CC ν cross⇥ section NEUT CC ν cross section between 3.5 GeV and 70 GeV, and thusτ the measured τ Cross-sections -1 -1 flux-averagedCross Section (10 charged current tau neutrino cross section: 10 10 σ(E)=σ E K(E), (10) Cross Section (10 const DONUT CC ντ cross section DONUT CC ντ cross section · · -2 -2 -2 10 38 2 10 10 (0.94 0.20) 10− cm . (9) ± ⇥ where σ(E) is the charged-current cross section per nu- SK measured CC tau cross section The measured cross section is shown together with the 10-3 10-3 cleon as a function of neutrino energy, σconst is the 0 20 40 60 theoretical cross10-3 sections and the MC simulations in Neutrino Energy (GeV) !13 asymptotic slope which is constant in σ/E for deepFig. 15. The measured0 and theoretical20 cross section val-40 60 inelastic scattering, and K(E) is the kinematic e↵ectues are consistent at the 1.5σ level. NeutrinoFIG. Energy 15. Measured (GeV) flux-averaged charged-current tau neutrino cross section (black), together with theoretical di↵eren- of tau lepton mass. DONUT measured σconst to be tial cross sections (⌫⌧ in red and⌫ ¯⌧ in blue), flux-averaged theoretical cross section (dashed gray) and tau events after 38 2 1 C. ComparisonsFIG. 16. Comparison of charged-current of tau the neutrino Super-K measured (marker with (0.39 0.13 0.13) 10 cm GeV in their final re- selection in MC simulations (gray histogram). The horizontal − − cross section measurement with previously reported ± ± ⇥ bar of the measurement point shows the 90% range of tau error bars) andresults expected tau neutrino cross sections (solid sults paper[40]. DONUT was incapable of distinguishing neutrino energies in the simulation. the charge of the ⌧ lepton, therefore, the measurement is lines) with σ(E) inferred from DONUT (dashed lines). The BecauseDONUT of the diffi crossculties section in tau neutrino considers production only DIS, and is is digitized an average of the ⌫ and⌫ ¯ cross sections assuming equal ⌧ ⌧ and detection,from[40]. charged-current tau neutrino cross sec- number of ⌫ and⌫ ¯ in the neutrino flux. tions have not been well measured. DONUT[14] and directly observed charged-current tau neutrino interac- ⌧ ⌧ OPERA[15] are the only two experiments that have tions, and DONUT is the only experiment that reported We wish to compare the ⌫⌧ cross section measured with atmospheric neutrinos by Super-K at relatively low energies to that measured by DONUT with a neutrino beam at higher energies. We recalculate the DONUT VII. CONCLUSION value of σ(E) from Eqn. 10 with the kinematic cor- rection K(E) integrated over neutrino energies between Using 5,326 days of atmospheric neutrino data in SK-I 3.5 GeV and 70 GeV and weighted to the world av- through SK-IV, Super-K measured the tau normalization erage ratio of cross sections between ⌫ and⌫ ¯ [37]. to be 1.47 0.32, excluding the hypothesis of no-tau- µ µ ± The calculated DONUT value of σ(E)isthenfurther appearance with a significance of 4.6σ. A flux-averaged weighted by the predicted ⌫⌧ and⌫ ¯⌧ flux ratio of 1.11 charged current tau neutrino cross section is measured to 38 2 for atmospheric neutrino tau appearance at Super-K. be (0.94 0.20) 10− cm for neutrino energy between ± ⇥ The resulting σ(E) is shown in Fig. 16. The charged- 3.5 GeV and 70 GeV in Super-K, to be compared with 38 current tau neutrino DIS cross section inferred from the the flux-averaged theoretical cross section of 0.64 10− ⇥ DONUT published number and rweightd to lower en- cm2. Our result is consistent with the previous DONUT 38 2 ergy is (0.37 0.18) 10− cm . This is smaller than result, and is consistent with the Standard Model predic- ± ⇥ 38 2 our measurement of (0.94 0.20) 10− cm ,butthe tion to within 1.5σ. measurements are not yet directly± ⇥ comparable. DONUT measured the cross section with a neutrino beam that had a much higher average energy than that of the tau ACKNOWLEDGMENTS neutrinos in the atmospheric neutrino flux at Super-K. Quasi-elastic scattering and resonant pion production is a We gratefully acknowledge the cooperation of the small component of the DONUT measurement and was Kamioka Mining and Smelting Company. The Super- neglected in their calculations. However, the tau neu- Kamiokande experiment has been built and operated trino flux at Super-K has a large component of neutri- from funding by the Japanese Ministry of Education, nos below 10 GeV, where CCQE and resonant pion pro- Culture, Sports, Science and Technology, the U.S.

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