Fundamental Physics with Askaryan Arrays Amy Connolly (The Ohio State University and CCAPP) Snowmass July 30 th , 2013 1 1
Outline • Introduction to radio Cerenkov technique and experiments • Cross-sections • Lorentz Invariance Violation • UHE Astrophysics • Conclusions See tomorrow’s talk by Abby Vieregg for more details on neutrino searches 2 2
Introduction to radio Cerenkov technique and experiments 3
Motivations for ultra-high energy (UHE) neutrinos (>10 18 eV) 1. Expect UHE neutrinos from GZK (Greisen-Zatsepin- Kuzmin) process: Cosmic rays >10 19.5 eV slowed by cosmic microwave background (CMB) photons within ~50 Mpc: p + γ CMB → ∆ ∗ → n + π + n → p + e − + ¯ ν ’s from GZK ν e process first π + → µ + ν µ pointed out by Berezinsky and µ + → e + ¯ ν µ ν e Zatsepin (1969) 2. Expect UHE neutrinos from UHECR sources: should produce UHE neutrinos through γ -hadronic interactions 4 4
Detection Techniques • <10 18 eV: optical dominates current constraints • >10 18 eV: radio dominates - Radio thresholds dropping with experiments coming online Cascades in atmosphere 5 5
Radio Cerenkov Technique (Askaryan Effect) • Coherent Cerenkov Idea by Gurgen signal from net “current,” Askaryan (1962) instead of from individual tracks • A ~20% charge asymmetry develops (mainly Compton scattering) • Excess moving with v > c/n in matter This effect has → Cherenkov Radiation dP ∝ ν d ν been confirmed experimentally in • If λ >> R Moliere → Coherent Emission sand, salt, ice: P ~ N 2 ~ E 2 PRL 86, 2802 (2002) λ > R Moliere → Radio/Microwave PRD 72, 023002 (2005) PRD 74, 043002 (2006) Emission PRL 99, 171101 (2007) R Moliere ≈ 10 cm, L ~ meters → Radio! 6 6
Antarctic Ice Ice thicknesses Radio Attenuation Lengths 1 km South Pole Ice [P . Gorham] 2 km depths are typical across the continent 7 7
Balloon Experiments Exavolt Antenna ANITA (EVA) Neutrino signal V-pol Long duration balloon program operated by NASA ANITA 1: 2006-2007 3 year NASA grant for ANITA 2: 2008-2009 engineering phase ANITA 3: 2014-2015 8 8
Askaryan Radio Array (ARA) University of Wisconsin, Ohio State University and CCAPP, University of Maryland and IceCube Research Center, University of Kansas and Instrumentation Design Laboratory, University of Bonn, National Taiwan University, University College London, University of Hawaii, Universite Libre de Bruxelles, Univ. of Wuppertal, Chiba Univ., Univ. of Delaware Askaryan Radio Array ARA − 37 200 m • Radio array at the South Pole depth 2 km - Testbed station, Stations 1,2&3 deployed last CLEAN AIR 3 seasons SECTOR South Pole • Phase1: 37 stations ~100 km 2 Operation zone CIRCLE QUIET IC - Establish flux DARK QUIET SECTOR • Phase 2: ~1000 km 2 SECTOR Runway - High statistics astronomy/ Legend: particle physics exploitation Power/comms cable Power/comms/calib. station Testbed station Production Station NSF has funded Testbed+3 Stations. Pending approval for next phase 9
ARIANNA • Radio array on Ross Ice Shelf http://arianna.ps.uci.edu • On track for completing 7 station array in Dec. 2013 • Propose 960 station array US Sweden New Zealand 10 10
-11 10 ) -1 ARA37 (3yrs) AraSim sr -12 -1 10 ARA3 (3yrs) AraSim s -2 E F(E) (cm ARA3 (1yr) AraSim -13 10 TestBed (3yr) AraSim -14 10 -15 10 -16 10 -17 10 ANITA II -18 10 Auger -19 IceCube40 10 RICE '11 -20 GZK, Kotera '10 10 GZK, ESS '01 -21 10 15 16 17 18 19 20 21 22 10 10 10 10 10 10 10 10 E (eV) 11 11
Cross sections 12
Why are ν N cross sections interesting? • Center of mass (COM) of UHE neutrino interactions with nuclei well exceed LHC energies - √ s= √ 2M N E ν , E ν =10 18 eV → √ s=45 TeV! • Predictions of SM ν N cross section ( σ ) at high energies rely on measurements of quark, anti-quark number densities at low x (parton momentum fraction) inaccessible with accelerators - E ν > 10 17 eV → x ≲ 10 -5 - HERA measures x ≳ 10 -4 - 10 -5 • ν N σ ’s at all energies needed to model experiments 13 13
ν N Cross Section Measurement with a Neutrino Telescope • Once an UHE ν sample is measured: • The distribution of ν zenith angles θ z would be sensitive to ν N cross sections • For E ν = 10 18 eV, E CM = 45 TeV! 14
Enhanced Cross Sections • Models with extra space-time ) SM 2 ( Cross Section / cm -28 x =1, N =1, M =1 TeV min D D x =1, N =7, M =1 TeV dimensions lead to enhanced min D D x =3, N =7, M =1 TeV min -29 D D x =1, N =7, M =2 TeV min ν N cross sections due to D D -30 micro-black hole production -31 J. Alvarez-Muniz and E. Zas, Phys. Lett. B411, 218 (1997) 10 -32 log 20 Number of events SM Connolly, et al., 18 x =1, N =1, M =1 TeV min -33 D D Phys.Rev.D83:113009,2011 x =1, N =7, M =1 TeV min D D 16 x =3, N =7, M =1 TeV min 6 7 8 9 10 11 12 D D x =1, N =7, M =2 TeV 14 min log ( E / GeV ) D D � 10 12 • These would modify the θ z 10 distributions from the 8 Standard Model (SM) 6 expectation 4 upgoing downgoing 2 • N D = # extra dimensions, 0 M D = reduced Planck scale, -0.2 0 0.2 0.4 0.6 0.8 1 cos � x min = M BHmin / M D z 15 15
Expected Constraints • Black bands: systematic x x =1, N =1, N =5, M =5, M =2 =2 x x =1, N =1, N =7, M =7, M =2 =2 min min min min D D D D D D D D uncertainty on SM cross 100 100 CL (%) CL (%) 90 90 sections 80 80 70 70 60 60 • Gray bands: statistical 50 50 40 40 30 30 uncertainties 20 20 1 1.5 2 2.5 3 1 1.5 2 2.5 3 log < n > log < n > p p 10 10 • On average, with 100 x x =3, N =3, N =5, M =5, M =2 =2 x x =3, N =3, N =7, M =7, M =2 =2 min min min min D D D D D D D D events, expect to exclude: 100 100 CL (%) CL (%) 90 90 80 80 • x min = 1, M D = 1, N D ≥ 2 70 70 60 60 x min = 3, M D = 1, N D ≥ 3 50 50 40 40 30 30 x min = 1, M D = 2, N D ≥ 3 20 20 1 1.5 2 2.5 3 1 1.5 2 2.5 3 log < n > log < n > Connolly, et al., p p 10 10 Phys.Rev.D83:113009,2011 • x min = 3, M D = 2, N D = 7 excluded with 110 events Most of these already excluded by the LHC. BUT unique opportunity to probe the theory w/ UHE neutrinos 16 16
Lorentz Invariance Violation 17
Lorentz Invariance Violation, Really? • Neutrinos are the only particles we can see from cosmic distances at the highest energies observed - It is natural that we should use them to test LIV • LIV falls naturally from many GUT models, L. Maccione, A. M. Taylor, D. M. Mattingly, & S. Liberati, JCAP 0904:022, (2009), P . Horava, Phys. Rev. D79, 084008 (2009); Phys. Rev. Lett. 102, 161301 (2009). • It has been proposed that the photon could be a Goldstone boson arising from LIV, R. Bluhm and V.A. Kosteleck ý , Spontaneous Lorentz Violation, Nambu-Goldstone Modes, and Gravity, Phys. Rev. D 71, 065008 (2005), Bjorken (1963) • It has been proposed that the graviton could be a Goldstone boson arising from LIV, V.A. Kosteleck ý and R. Potting, Gravity from Spontaneous Lorentz Violation, Phys. Rev. D 79, 065018 (2009) • It is possible that both the photon and graviton are both simultaneously Goldstone bosons from LIV 18 18
Lorentz Invariance Violation (LIV) • If neutrinos can exceed speed of light then can “brem” - ν → ν ʹ e + e - (Coleman and Glashow) - Neutrino loses ~3/4 of its energy • Effectively a “decay” with time constant: − 5 α ν − 3 s τ ν = τ CG E ν , GeV with τ CG =6.5 × 10 -11 s - α ν is a measure of level of LIV E ν =p ν c(1+ α ν ) • Over cosmic distances, neutrinos above an energy will all brem, show up at lower energies P .W. Gorham, A. Connolly et al., Phys.Rev. D86 (2012) 103006 19 19
Lorentz Invariance Violation (LIV) P .W. Gorham, A. Connolly et al., Phys.Rev. D86 (2012) 103006 Attenuation vs. redshift Observed neutrino spectra, adapting CRPropa outputs Different energies, same α ν = 8 × 10 -26 Different values of log 10 α ν 20 20
ANITA Results • Set lower limit on LIV parameter α ν assuming LIV was the reason for the models evading detection All the experimental results searching for violations of Lorentz invariance (Data Tables for Lorentz and CPT violation) published in Rev. Mod. Phys.83:11 (2011); the P .W. Gorham, A. Connolly et al., annually updated version can be Phys.Rev. D86 (2012) 103006 found here arXiv:0801.0287. 21 21
UHE Astrophysics 22
Neutrinos are Unique Probes of UHE Astrophysics • Will be only particles >10 19.5 eV from ≳ 100 Mpc Neutrinos from p − γ interactions Protons from sources · 10 − 2 Distance to proton source (Mpc) Distance to proton source (Mpc) 0 . 3 1 . 5 10 3 10 3 Probability Probability 0 . 2 1 10 2 10 2 0 . 1 0 . 5 10 1 0 10 1 0 10 18 10 19 10 20 10 21 10 18 10 19 10 20 10 21 Energy of injected proton (eV) Energy of injected proton (eV) Plots made with the help of CRPropa 2.0 E -1 spectrum, flat redshift evolution 23 23
Recommend
More recommend
