3+1 sterile neutrino @nufact
DESCRIPTION
Jacobo López–Pavón IFT UAM/CSIC. 3+1 sterile neutrino @NuFact. NuFlavour Coseners House, Abingdon, UK 8-10 June, 2009. Based on a collaboration with: Andrea Donini, Ken-ichi Fuki, Davide Meloni and Osamu Yasuda e-Print: [arXiv:0812.3703]. Motivations. - PowerPoint PPT PresentationTRANSCRIPT
3+1 sterile neutrino @NuFact
Jacobo López–Pavón
IFT UAM/CSIC
NuFlavourCoseners House, Abingdon, UK
8-10 June, 2009
Based on a Based on a collaboration with: with:
Andrea Donini, Ken-ichi Fuki, Davide MeloniAndrea Donini, Ken-ichi Fuki, Davide Meloniand and
Osamu YasudaOsamu Yasuda
e-Print: [arXiv:0812.3703]e-Print: [arXiv:0812.3703]
Motivations
• Neutrino masses and mixing → evidence of Physics Beyond the SM
• Sterile neutrinos strongly affect the oscillation physics
• This is what LSND seems to indicate: the existence of a fourth sterile neutrino, much heavier than the rest light neutrinos.
• Experiments such as MiniBoone do not confirm the LSND results.
• Difficult to accommodate all oscillation data including LSND in 4 neutrino models. Tension remains in 3+2 and 3+3 models.
Motivations
• Sterile neutrino scenarios which satisfy all neutrino oscillation data except LSND are still possible.
• Many theories of NP have in their low energy spectrum singlet fermions.
• The simplest extension to account for neutrino masses: SM + singlet fermions with a Majorana mass term.
Following the renormalization group analyses, M can be anything:
2
i
ii
dMM Y
d
as it is dictated by chiral symmetry.
If M is small, lepton number is partially conserved: this range of values is natural. Motivation for not assuming as usual.
EWM
We will analyze the future sensitivity to the new parameters associated to the 3+1 sterile model in a NuFact, without imposing LSND constraints but considering the information from the rest of
present experiments.
Study of CP violation in the context of sterile neutrino
Goals
Set-up• 50 GeV NuFact useful muon decays/year/baseline
Hybrid-MIND detectors @ L=3000 km and L=7500 km Both polarities running for 4 years each
202 10
VS
205 10
• 20 GeV NuFact (ISS scenario)
useful muon decays/year/baseline
Hybrid-MIND detectors @ L=4000 km and L=7500 km Both polarities running for 4 years each
4kton MECC+50kton MIND
4kton MECC+50kton MIND
Why we consider this set up?
It is well known that the higher energy we have, the better we can explore the New Physics.
An evident motivation: the channel is a very interesting one to study New Physics.
Parametrization
2 0solm 1 disappears
It reduces to the standardcase if sterile neutrinodecauple
Can be put anywhere
Since we are interested in the atmospheric regime, ,Let us take advantage of the following parametrization:
Probabilities in matterExpanding with respect the following small parameters…
New possible CP-violation Signal !
Best sensitivity to 34 24,
Golden and Silver do not seem to be the best option to study sterile neutrinos
23 421
2
m L
E
Probabilities in matter
• Golden and Silver seems to be not so useful for constraint sterileNeutrino physics.
• We will focus on the sector. At the probability level, we can say is the best channel to see a possible sterile signal, moreover, is the best one to see the new CP-violation associated.
• This can be shown for other NP cases. For this reason we will call him:
• In anycase, we have analyzed all the possible channels
Sensitivities
Sensitivity to : Golden and Silver channels13 14,
NuFact 50 GeV90%CL
• Sensitivity to : it is not improved the present bound14
• Sensitivity to similar to the standard analyses: long baseline better.
13
NuFact 20 GeVA bit better
Golden
Golden+Silver
Sensitivity to : disappearence & discovery 24 34,
NuFact 50 GeV NuFact 20 GeV
90%CLA bit better
Without correlated systematic error Uncorrelated+correlated
systematics (conservative)
Signals
Could we measure the new phases ?
Can we measure the new phases ?
Which would be the best channel?
?e ?e ?
New possible CP-violationEffect!!
•
• Golden & Silver probabilities are very suppressed by small parameters:
The new CP phase can be probed
99% CL
24 34 3 312 sin sinN N s s
1. Confusion between 31( )sign sign
L=3000 km
L=7500 km
NuFact 50 GeV
24 5º
Conclusions
• Analyze 3+1 neutrino sterile physics @ NuFact. Comparing two set-ups:
- E=50 GeV; useful muon decays/year/baseline; Hybrid-MIND detectors @ L=3000 km and L=7500 km.
- E=20 GeV; useful muon decays/year/baseline; Hybrid-MIND detectors @ L=4000 km and L=7500 km (ISS scenario).
• Golden & Silver results not very useful to constrain the new parametersassociated to the 3+1 sterile neutrino model.
•The sensitivity to is basically the same as the 3-family analyses one.
202 10
205 10
13
ConclusionsNuFact 50 GeV
24
34 º12º7.5
Present
º31º12
• CP-asymmetry is a clean probe of the new phases. This is not new, can be seen for New Physics as NSI or the MUV scheme (hep-ph/0703098). For this reason we call this channel the “Discovery channel”.
24 34
• 50 GeV NuFact performs better than the ISS scenario due to the larger taucross section. Nice sensitivities to and thanks to the sector
• Better results can be achived if we are able to improve the tau detectors (“Discovery channel” has nice statistics).
NuFact 20 GeV
º14º8
Back-up slides
Probabilities Golden&Silver
8
6
6
The new CP phase can be probed
99% CL
24 34 3 132 sin sinN N s s
1. Confusion between 13( )sign sign
L=3000 km
L=7500 km
NuFact 50 GeV
The new CP phase can be probed
99% CL
24 34 3 132 sin sinN N s s
1. Confusion between 13( )sign sign
Disappearence L=3000 km
DiscoveryL=3000 km
NuFact 50 GeV
Disappearence3000+7500 km Discovery
L=7500 kmDiscovery
3000+7500 km
The new CP phase can be probed
99% CL
24 34 3 132 sin sinN N s s
1. Confusion between 13( )sign sign
Disappearence L=3000 km
DiscoveryL=3000 km
NuFact 50 GeV
Disappearence3000+7500 km Discovery
L=7500 kmDiscovery
3000+7500 km
• HybridMIND=4kton MECC+50kton MIND
• MIND (ISS detector report)
above 10 GeV
Increasing linearly from at 1 GeV
above 1 GeV (the MINOS one)
• MECC (Magnetized Emulsion Cloud Chamber)
above 5 GeV
Experimental details: Detector Efficiencies
Placed in front of MIND
ArXiv: hep-ph/03051805 x 5, thanks to magnetization decays into e and into hadrons can be used in addition to decay (only the 17% of the total)
Experimental details: Backgrounds & Systematics• Golden: B= dominated by right-sign muons with wrong charge assigment and charmed meson decays .• Disappearence: B= negligible. Systematic-dominated. We’ve checked this including B= , all wrong-sign muon events and right-sign muons coming form discovery oscillaton with tau decaying into muons.
610
• Silver & Discovery: ArXiv:0704.0388
ArXiv: hep-ph/0305185
5NC10 N
x 5
where
analyses2
• Sensitivities
Correlated systematic errors
max min/jE E E
analyses2
Uncorrelated bin-to-bin systematic errors
With given just above.
• Signal
j
Discrimination between 3 and 4 family
Where is the prior from the 3+1 sterile oscillation Analyses of atmospheric and reactor data.
NuFact 50 GeV NuFact 20 GeV
Discrimination between 3 and 4 family Disappearence & Discovery
90%CL
Discrimination between 3 and 4 family Golden & Silver
NuFact 50 GeV NuFact 20 GeV
90%CL
Can the measurement of the 3-family Dirac phase be affected
by the sterile neutrinos ?
Measurement of the standard 3-family phase
Combination
L=3000 km
L=7500 km
Standard analyses
• For small values of almost no differences with 3-family case.24 14,
99%CLGolden + Silver
Measurement of the standard 3-family phase
Combination
L=3000 km
L=7500 km
Standard analyses
• Some sensitivity @ the “Magic Baseline” Sterile neutrino effect !
99%CLGolden + Silver
Mesurement of the standard 3-family phase
• For small values of no differences with 3-family case.
• Close to the upper bound, 3+1 contourns are orthogonal to3-family ones.
13 14,
• The sensitivity @ L=7500 km would be a sterile physics effect.
Competitive
Sensitivity to : disappearence & discovery 24 34,
90%CLNuFact 50 GeV
2242 ...s
Sensitivity to : disappearence & discovery 24 34,
90%CLNuFact 50 GeV
2242 ...s
Sensitivity to : disappearence & discovery 24 34,
90%CLNuFact 50 GeV
2242 ...s
Probabilities mu/tau sector 14 13 0
Improving tau detection
Improving tau detection
Sensitivity to : Golden and Silver channels13 14,
NuFact 50 GeV
90%CL
• Sensitivity to : it is not improved the present bound14
• Sensitivity to similar to the standard analyses: long baseline better.
13
Golden
Golden+Silver
Sensitivity to : Golden and Silver channels13 14,
90%CL
• Sensitivity to : it is not improved the present bound 14
• Sensitivity to similar to the standard analyses. 13
NuFact 20 GeV
Golden
Golden+Silver