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Earth matter effects at very long baselines and the neutrino mass hierarchy

DSpace at IIT Bombay

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Title Earth matter effects at very long baselines and the neutrino mass hierarchy
 
Creator GANDHI, R
GHOSHAL, P
GOSWAMI, S
MEHTA, P
SANKAR, SU
 
Subject atmospheric neutrinos
oscillation experiments
super-kamiokande
cp violation
3-neutrino oscillations
parametric-resonance
global analysis
future
detector
macro
 
Description We study matter effects which arise in the muon neutrino oscillation and survival probabilities relevant to atmospheric neutrino and very long baseline (> 4000 Km) beam experiments. The interrelations between the three probabilities P(mu e), P(mu tau), and P(mu mu) are examined. It is shown that large and observable sensitivity to the neutrino mass hierarchy can be present in P(mu mu) and P(mu tau). We emphasize that at baselines > 7000 Km, matter effects in P(mu tau) are important under certain conditions and can be large. The muon survival rates in experiments with very long baselines thus depend on matter effects in both P(mu tau) and P(mu e). We also indicate where these effects provide sensitivity to theta(13) and identify ranges of energies and baselines where this sensitivity is maximum. The effect of parameter degeneracies in the three probabilities at these baselines and energies is studied in detail and large parts of the parameter space are identified which are free from these degeneracies. In the second part of the paper, we focus on using the matter effects studied in the first part as a means of determining the mass hierarchy via atmospheric neutrinos. Realistic event rate calculations are performed for a charge discriminating 100 kT iron calorimeter which demonstrate the possibility of realizing this very important goal in neutrino physics. It is shown that for atmospheric neutrinos, a careful selection of energy and baseline ranges is necessary in order to obtain a statistically significant signal, and that the effects are largest in bins where matter effects in both P(mu e) and P(mu tau) combine constructively. Under these conditions, up to a 4 sigma signal for matter effects is possible (for Delta(31)> 0) within a time scale appreciably shorter than the one anticipated for neutrino factories.
 
Publisher AMER PHYSICAL SOC
 
Date 2011-10-13T22:40:54Z
2011-12-15T09:16:16Z
2011-10-13T22:40:54Z
2011-12-15T09:16:16Z
2006
 
Type Review
 
Identifier PHYSICAL REVIEW D,73(5)-
1550-7998
http://dx.doi.org/10.1103/PhysRevD.73.053001
http://dspace.library.iitb.ac.in/xmlui/handle/10054/13867
http://hdl.handle.net/100/3078
 
Language en