1 / 16

Search for exotic contributions to Atmospheric Neutrino Oscillations

Search for exotic contributions to Atmospheric Neutrino Oscillations. G. Giacomelli, V. Popa, M. Sioli University of Bologna and INFN Venezia, 22-25/2/2005, “ Neutrino Telescopes ”. - Introduction - Monte Carlos - Final oscillation analyses - Search for LIV contributions

urian
Download Presentation

Search for exotic contributions to Atmospheric Neutrino Oscillations

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Search for exotic contributions to AtmosphericNeutrino Oscillations G. Giacomelli, V. Popa, M. Sioli University of Bologna and INFN Venezia, 22-25/2/2005, “NeutrinoTelescopes” - Introduction - Monte Carlos - Final oscillation analyses - Search for LIV contributions - Conclusions

  2. Upthroughgoing In up Absorber Streamer Scintillator In down Upstop 1) 4) 3) 2) MACRO DATA SAMPLES(measured) (Bartol96 expected) __________________________ Upthrough(1) 857 1169 In up(2) 157 285In down(3)+ Up stop(4) 262 375

  3. Atmospheric n flux. Monte Carlos - Until 2001 Bartol96 (Honda96) - After 2001FLUKA2001-3 (Honda2001-3) Both 3-dimensional improved interaction models new cosmic ray fit, ..... They agree to ~5% But: Predictions of new Honda and FLUKA MCs H.E. 25% low ; L.E. 12% low - Angular distributions of Bartol96, new Honda and FLUKA MCs agree to ~<6% New L3cosmic data favor Bartol96, … astro-ph0502380

  4. MACRO data MonteCarlos Upthroughgoing n1

  5. En = 13 GeV En = 36 GeV MC predictions for nm nt oscillations with the MACRO parameters En = 88 GeV En =146 GeV nm energy estimate through Multiple Coulomb Scattering of upthroughgoing muons in rock in lower MACRO(Phys. Lett. B566 (2003) 35) 300 events with θ<60 degrees No oscillation Bartol96

  6. MC predictions for nm nt oscillations with the best MACRO parameters L/En distribution From the muon zenith distribution From the measurement of the muon energy using Multiple Coulomb Scattering Upthr. m data IU m data 12% point-to-point syst. error

  7. Best fit parameters for nm nt Dm2 = 2.3 10-3 eV2 ; sin2 2q =1 Eur. Phys. J. C36(2004)357 Final oscillation analyses Use ratios with uncertainties of ~5%, independent of MCs { Zenithdistribution R1= N(cos Q < -0.7) /N(cosQ > -0.4) H.E. R2= N(low En) / N(high En) En estimate IU, ID and UGS m R3= N(ID+UGS) / N(IU) L.E. No oscillation hypothesis ruled out by ~ 5 s Absolute values referred to Bartol96 MC : R4=(Data/MC)H.E. ; R5=(Data/MC)L.E. With these informations, the no oscillation hypothesis is ruled out by ~ 6 s

  8. MACRO D q

  9. Mass induced oscillations 2 n flavor interpretation: induced by the mixing of 2 mass eigenstates , and 2 weak eigenstates , : The survival probability is

  10. Exotic oscillations Lorentz invariance violation (LIV) For LIV oscillations: there is mixing between 2 flavor eigenstates and 2 velocity eigenstates: (asymptotic vn different from c) The survival probability is: ( v=v3-v2 ) Notice the dependence LEn  LIV is not dominant Violation of the equivalence principle Similar results as for LIV, but with parameter fD (fD= difference of coupling constants of n to gravitational pot f)

  11. Mixed oscillations If both mass-induced and LIV-induced transitions are considered simultaneously: where and

  12. P(nmnt) Mixed oscillations

  13. 2 analysis We computed upper limits of LIV parameters v , sin2 2θv -using the formalism of Coleman-Glashow PL B405(1997)249; hep-ph/0407087 , -taking the Nlow, Nhigh samples of low and high energy muon upthroughgoing data with cuts - as for MACRO mass oscillation analysis - optimized for LIV search -fixing Dm2=0.0023 eV2 and maximal mixing (MACRO values) -minimize with respect to Dv, θv the function 90% C.L. limits on v and θv computed with Feldman–Cousins prescription

  14. (30,130) GeV (28,142) GeV

  15. Maximum Likelihood analysis in intermediate En region Event-by-event analysis best use of existing information 106 events with Minimization of the negative log-likelihood function: Method tested on “mass-induced” oscillations  MACRO parameters well reproduced Average v < 10-25, slowly varying with m2

  16. Conclusions • The inclusion of LIV effects does not improve the fits to the muon energy data • The limits for LVI parameters at 90% CL are at sin22θv = 0 : Dv/2 < 3 10-24 at sin22θv = 1 : Dv/2 < 1.4 10-26

More Related