Can we see CPviolation in leptons at FNAL Case study presented

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Can we see CP-violation in leptons at FNAL? ?
Case study presented

• Mayda M. Velasco
• Northwestern Univ.

On behalf of Proton Driver Working
Group G.Barenboim, A.DeGouvea, T. Dombeck,
N.Grossman, D.Harris, D.Michael, M.Szleper, S.
Werkema
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CP violation in ?s

• By now we know that the amount of CP-violation
• observed in quarks is not enough to explain the
  difference
• in abundance between matter and anti-matter.
• Could Leptogenesis be the answer?
• If so, CP violation in the ? sector is one of the
  
• ingredients needed for the model to
  workTherefore
• it is very important to look for CP violation in
  neutrino
• oscillations!
• . Recall recent WC by Parkes and Kayser

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Evidence for n-oscillations

• 3 experiments observed
• LSND effect , P(nm?ne) MiniBoone to confirm or
  refute this result.
• Atmospheric neutrinos P(nm? nt ) very convincing
  results from SuperK, K2K, etc.!
• Solar neutrinos, LMA most likely P(ne?nX) solar
  models now well understood data look convincing
  SuperK, SNO, etc.

Dm2 (eV2)
LMA
X
sin2 2q
SMA now excluded
VAC lt10-7 eV2
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?-oscillations in the near future
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At the moment will focus only on atmospheric and
solar ? observations

• The reasons are
• We have a large Dm2 range? impossible to have
  only 3 ? involved if all of the effects are due
  to ?-oscillations.(Theory cannot accommodate them
  all)
• Either some of the data are not due to
  oscillations, or there must be at least one
  undiscovered sterile neutrino or there must be
  CPT violation in the ?-sector
• ?In either case, we ignore LSND for now

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However, keep in mind that our choices have been
wrong before. ?In 1990 we thought (Murayama)

• Solar problem must be solved by small mixing
  angle
• Scale for ??? ?? oscillation should be ?m2
  10-100 eV2
• Mixing angle for ??? ?? is of the order of Vcb
• Atmospheric neutrino anomaly must go away

wrong!
wrong!
wrong!
wrong!
4.
1.
2.
3.
Nevertheless, for now lets ignore sterile
neutrinos and assume CPT, but keep an open mind.
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In this case, Mixing for 3 ?
ne Ue1 Ue2 Ue3 n1 nm Um1 Um2
Um3 n2 nt Ut1 Ut2 Ut3 n3
Flavor Eigenstates
Mass Eigenstates
Dm232 (m32 - m22)?atm, Dm122 (m22 - m12)?sun
P(a ? b) SS UaiUbiUajUbj exp-i(mi2-mj2)L/2E
PCP-even(a ? b) PCP-odd(a ? b)
P(a ? b) P(? ? b) PCP-even(a ? b)
-PCP-odd(a ? b)
? Ignoring matter effects for the moment
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CP ?-phase in the Ue3 matrix element
Ue3
Chose the Maki-Nakagawa-Sakata (MNS) Matrix

• cij cos qij sij sin qij
• Maximal Mixing has q12 q13 q23 45o
• Ue3 accessible from P(nm?ne) measurements

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CAUTION P(nm?ne) depends on ?-phase, matter
effects, Dm223(including sign) ,?23, Dm212 ,? 12
? 13.
Minakata, Numokawa,Parke
P(nm?ne)
Sign of Dm223 or Dm213
P(nm?ne)
Multiple solution depending on ?, therefore we
will need several experiments (nm nm) to
understand CPviolation in ?-oscillation!
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How could we detect CP-violation in leptons at
FNAL? NuMI Off-axis n-oscillation experiments

• NUMI is a great investment expand its
  capabilities with a detector placed at angle from
  beam axis
• STAGE-1 precision measurements of atmospheric
  parameters look for P(nm?ne)
• ? LOI already in progress!
• STAGE-2 Add proton driver upgrade and measure
  P(nm?ne) P(nm?ne) get ?-phase.

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Nominal NuMI-MINOS Conditions ON-AXIS
Add NuMI OFF-AXIS detector
Off Axis allows us to change En spectra to
optimize L/En using a beamline that is already
under construction!
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OAB? Conservation of Energy bounds E? for a
given ??
Lower tails
Higher intensity
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OAB with and without oscillations_at_ NUMI low
energy configuration
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By changing Horn Polarityrun for either nm
anti-nm beam
3-5x higher rate for nm
nm/anti-nm
Want more Protons when running for anti-nm beam
E
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NuMI Medium Energy (735km,10km)

Focus on ?µ??e to see Matter Effects
nm
ne / nm
anti-nm
-
Off Axis ( 13.6 mrad )
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Matter Effects(MaEf)
Barenboim, De Gouvea
NUMI 2GeV --- Large MaEf Not visible at JHF
ne
ne
Anti-ne
En
Vacuum
Anti-ne
Transition probabilities Dm21210-4 eV2
En2 GeV
L
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NUMIx4 Future Off Axis beams ?Matter Effects
CP violation
ne appearance Ue32 atmospheric parameters to
1
Start with nm STAGE 1
NUMI As is
Prot. Upgrade And/or gtmass
nm
nm
anti-nm
CP-phase d STAGE 2
anti-nm
Matter Effects STAGE 2
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Physics to be measured _at_ STAGE 2
All 3-type of measurements require nm anti-nm
beam
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3 scenarios based on latest solar oscillation
observations
HLAM LMA
NLMA
Vacuum
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Assumed Detector Segmented Calorimeter --5
yrs(1.5 yrs with PD)

• 20Kton SOMINOS
• gt40 signal, lt0.2 NC
• Using ?µ??µ disappearance
• measure
• Uncertainty in sin2 2?23 .01
• Uncertainty in ?m223 10-4
• Realistic beam, full detector
• simulation reconstructions Szleper Velasco

D. Harris
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Compare NuMI JHF (STAGE-1)

• 5 Year -- maximal mixing
• (Ue320.025, Dm2 23 0.003 eV2)
• JHF (0.75MW 112 Kton)
• ?e Signal 123 events
• Background 22 events
• SOMINOS (0.4MW 120Kton)
• ?e Signal 165 events
• Background 27 events
• Both exp. 20x better than what
• we have at the moment!

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Anti-nm requires 3 times more beam time physics
requires _at_ least 100kTon yrs for nm
Only realistic to think of STAGE 2 program
if Assume 120 kt-year with nm 300 kt-year with
anti-nm 20kT-SO-MINOS (5 years program with
Proton Upgrade vs 20 years without proton Driver
Upgrade)
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First look at NLMA-Vacuum

• Less realistic case, but good to understand the
• advantages of having a good detector and clean
• beamline in the analysis of Ue3
• No so sensitive to the atmospheric parameters
• uncertainties.

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NLMA Pure ?µ??e due to atmospheric parameters
probability smaller for inverted hierarchy
CP-odd phase not observable but Ue32
measurements independent of phase
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NLMA Look for ?µ??e 20Xbetter than current
bounds (0.05)
MINOS 5yr X 5.5kt
SOMINOS 5yr 20kt X 4UP
3?
2?
SOMINOS 5yr X 20kt
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NLMA Assume just 100kton/yrs forget about
anti-neutrino running if JHF exist for Hierarchy
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NLMAPD (120300kTon years) Hierarchy ?CPT more
important !
Is ?m2 the same?
Assumed solution
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Look at High LMA? HLMA

• Assume atmospheric parameters to be know
• to 1
• Assume positive hierarchy

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HLMAPD Confusion between Ue32 ? d, Dm2 12
Uncertainty in Dm212 gives extra tails
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LastLook at LMA

• Assume hierarchy to be positive
• Assume atmospheric parameters to be
• known to 1

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LMAPD PD becomes crucial even to just set
limits
120 kTon/yr
300 kTon/yr
d is the CP phase sensitivity to Ue32
depends on d
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LMAPD Assume a measurement is performed with
given luminosity ?µ??e events are seen
Assumed value of Ue3 2
Other cases
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Using more conservative parameters Dm212 5x10-5
P(nm?ne) ? 0.02?0.002
P(nm?ne)
P(nm?ne) ? 0.01?0.004
P(nm?ne)
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In all cases we have good capabilitiesbut we
have not talk about the ambiguities between ?
and Ue32 (?13 )

• ?23 ? ?/4 ? the ?23 ?/2 - ?23 gives the same
  oscillation amplitudes
• We need to know the mass hierarchy
• Can we get it by comparing P(nm?ne) results from
  JHF-SuperK with NUMI-Offaxis? Probably yes
• Could we understand ambiguities by running (nm
  nm) X (2 baselines)?

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2 Baselines 2 detectors or 2 beamlines

• Can we be smart enough to think ahead try to
  prepare to solve this ambiguities
• Detectors without directionality (L. Argon,
  Cerenkov)
• Movable 20kTon detectors ?

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Conclusions for Neutrinos

• Offaxis experiments with the current design of
  NUMI could provide a 1 measurements in the
  atmospheric parameters and a good reach in Ue32
  if we invest in the proper detector.
• 20 Kton Highly segmented calorimeter
• 5Kton ICARUS
• OABPU (4XNUMI) could expand significantly the
  reach while continuing to use the same detector
  and give access to CP violation in the lepton
  sector and/or MaEf ? In all possible SOLAR
  SOLUTIONS