Search for exotic contributions to Atmospheric Neutrino Oscillations

1
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 - Conclusions
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MACRO
DATA SAMPLES(measured) (Bartol96
expected) __________________________ Upthrough(1)
857 1169 In up(2) 157 285
In down(3) Up stop(4) 262 375
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1984 MACRO Proposal
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Early analyses

• Upthrough m only Angular distribution
• Absolute value
  (Bartol96 MC)
• 
  
• Dm20.0025 eV2
  Phys.Lett. B434(1998)451
• Maximal mixing
  Phys.Lett. B517(2001)59
• Lower energy topologies consistent with upthrough
  m

nm energy estimate through Multiple Coulomb
Scattering of upthroughgoing muons
Phys.Lett. B566(2003)35
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Atmospheric n flux. Monte Carlos
- Until 2001 Bartol96 (Honda96)
- After 2001 FLUKA2001-3 (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 lt6 New
L3cosmic data favor Bartol96,

astro-ph0502380
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MACRO data MonteCarlos Upthroughgoing
n1
7
nm energy estimate through Multiple Coulomb
Scattering of upthroughgoing muons in rock in
lower MACRO
(Phys. Lett. B566 (2003) 35)
300 events with ?lt60 degrees
No oscillation Bartol96
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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
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Low Energy Neutrino Events
Internal Up
Internal Down Up-stopping m
Measured (points) and expected number (dashed
lines MC Bartol96) of upgoing semicontained
events (left) and up-stopping plus downgoing
semicontained m (right). Solid lines
oscillations with the best fit parameters
sin22Q1 and Dm20.0023 eV2. ltEngt 2.3 GeV
. Monte Carlo scale uncertainty 21
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Final oscillation analyses
Use ratios with uncertainties of 5, independent
of MCs

R1 N(cos Q lt -0.7) /N(cosQ gt -0.4)
Zenith distribution
H.E.
R2 N(low En) / N(high En)
En estimate
IU, ID and UGS m
R3 N(IDUGS) / 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
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MACRO
D
q
12
Mass induced oscillations
2 n flavor interpretation
induced by the mixing
of 2 mass eigenstates
,
and 2 weak eigenstates
,

The survival probability is
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Exotic oscillations Lorent
z 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 ( ?vv3-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)
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Mixed oscillations
If both mass-induced and LIV-induced transitions
are considered simultaneously
where
and
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(No Transcript)
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P(nm?nt) Mixed oscillations
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?2 analysis
We computed upper limits of LIV parameters ?v ,
sin2 2?v -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
Dm20.0023 eV2 and maximal mixing (MACRO values)
-minimize with respect to Dv, ?v the function
90 C.L. limits on ?v and ?v computed with
FeldmanCousins prescription
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(30,130) GeV
(28,142) GeV
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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 lt 10-25, slowly varying with ?m2
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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 sin22?v 0 Dv/2 lt 3 10-24
• at sin22?v 1 Dv/2 lt 1.4
  10-26