M

1
M
b-beams
P. Hernandez Univ. Valencia and IFIC
2
Weakly interacting n can feel the vacuumin a
extremely weak way
Goals and motivation

• the other n helicity states
• an L violating scale M can explain the splitting

The link to the visible world of this new physics
is the n mass matrix
3

• and not just a typical CKM
• (Ufi,Ufj,Ufk)
  

Maximal mixing in the 23 sector seems to imply
redundancy
symmetry ?
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• Fundamental questions in lepton flavour
• what are the other helicity states Weyl,
  Majorana, decoupling physics ?
• what are the scales and dynamics involved in
  the interactions of these new fields? Is it a
  decoupling scale M gtgtv or is there a hidden
  sector around the corner (M ltv)
• is L number violated ?
• are n relevant in cosmology and in the genesis
  of baryons ?
• The answers will provide a new perspective into
  the flavour puzzle and the hierarchy problem

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• Our safest bet is to measure precisely the light
  n mass matrix
• overconstrain the PMNS matrix to see that it is
  not the whole story
• test symmetries CP, CPT, maximal mixingto give
  us a clueon the new interactions

A determination of the neutrino mass matrix is a
necessary though not sufficient condition
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Standard 3n scenario
The observables
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The unknowns


q13 a1, a2
d
Hierarchy 0nbb
m21, m23
0nbb, bb Cosmology
sign(cosq23)
Precise n oscillations

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The knowns

• q23 , q12, Dm 223, Dm 212
• Precise n oscillations
• More precision and overconstraining the known
  parameters will also be important
• to resolve correlations with the unknown ones
• search for new physics or symmetries test of
  unitarity of the PMNS, establish maximal mixing

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The challenge

• Tunning En/L Dm2 ij we can enhance different
  terms even in
• the same channel
• 
  

Measure small oscillation probabilities or
measure large ones with high accuracy
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Sensitivity to unknows at En/L Dm223
Golden
Silver
e ? small parameters q13, D12/D23

vac/matter
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Sensitivity to knowns at En/L Dm223

e ? small parameters q13, D12/D23


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Terrestrial precision n oscillation experiments
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The b-beam

• At accelerators we can also do electron
  (anti)-neutrino beams
• above m threshold that are pure from radioactive
  decays

P. Zucchelli
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n fluxes
oscillation peaks
machine
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CERN baseline Scenario
CERN-Frejus

• Uses maximally existing infrastructure

M. Lindroos M. Mezzetto
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The case for a greenfield study the higher the
g the better

• more signal Ncc F x sn , sn E, E2
• more significant energy dependence intrinsic
  degeneracy
• more significant matter effects hierarchy

Burguet-Castell,Casper, Gomez-Cadenas, P.H.
Sanchez
Bring the b-beam to the forefront and find out
the machine needed to achieve
?
E.g. Refurbished SPS
Eg. CERN-Canfranc
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Detectors

• No magnetization needed
• m for the appearance signal
• e for the disappearance signal
• good energy resolution

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Water Cerenkov technology
At high energy this detector is no longer good,
because the neutrino energy cannot be
reconstructed in the inelastic region
glt400
Burguet-Castell,Couce,Casper, Gomez-Cadenas,P.H.
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Comparing b-beams

• Baseline scenario

• CERN-Frejus at optimal g ggt 100
• ggmaxSPS 150 at optimal L L300km

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• g350, L730km, Nb 3/1 x1018
• 
  
  
  

Comparing b-beams

• conservative greenfield scenario

• g350, L730km, Nb3/1 x1018

Burguet-Castell et al
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Degeneracies

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Sensitivity to discrete ambiguities
Hierarchy, t23
5x10-3
sin22q13
0.04
No big advantage in asymmetric option gNe/gHe1.67
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Does the SPL-SPS-superbeam still help ?
Mezzetto
Donini et al, degeneracies
It does not help with degeneracies
Donini,Fernandez,Rigolin
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NOnA
ggt 500, scintillator should outperform water
Huber, Lindner, Robinec, Winter
Homework comparison of the two technologies for
the on the same footing that is same g, and g/L
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Also in the same work

• Effect of the uncertainty in atmospheric and
  solar parameters
• included but not quantified separately
• Homework answer the question, is T2K
  enough ?
• (also Donini, Meloni,Rigolin for baseline
  scenario)
• Dependence on the ratio of neutrinos/antineutrino
  events

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g O(103)

• Calorimeter 40kton g1500, L3000km
• Burguet-Castell, Casper,
  Gomez-Cadenas, P.H., Sanchez
• No gain with respect to the g350 option as
  regards CP
• NOna 50kton g1000, L1300km
• Huber, Lindner,
  Robinec,Winter

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Use the rock sorrounding the underground lab as
target and look at the muons with a instrumented
surface
Terranova,Marotta,Migliozzi,Spinetti
The effort required to get to gO(103) is
probably espectacular
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1019 ions/year ?
4 x1019 He, 0.8 x 1019 Ne, 400Kton
4 x1019 He, 0.8 x 1019 Ne, 80Kton
2.9 x1018 He, 1.1 x 1018 Ne, 400Kton
Preliminary
E.Couce
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Summary
b-beam is a beautiful concept to create pure ne
beams synergies with the nuclear physics
community Most likely below t threshold only
em, ee Detector could be a Mton water Cerenkov
versatile experiment, but also a smaller
scintillator a la NOnA A greenfield design is
necessary to do a fair comparison to the Nufact
-Very good (comparable) sensitivity d
and q13 -Some (not comparable)
sensitivity to the hierarchy and
octant longer L, silver channel
-Necessary to combine with T2K for atmospheric
enough?