Title: Can we see CPviolation in leptons at FNAL Case study presented
1Can 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
2CP 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
3Evidence 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
4?-oscillations in the near future
5At 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
6However, 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.
7In 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
8CP ?-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
9CAUTION 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!
10How 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.
11Nominal 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!
12OAB? Conservation of Energy bounds E? for a
given ??
Lower tails
Higher intensity
13OAB with and without oscillations_at_ NUMI low
energy configuration
14By 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
15NuMI Medium Energy (735km,10km)
Focus on ?µ??e to see Matter Effects
nm
ne / nm
anti-nm
-
Off Axis ( 13.6 mrad )
16Matter 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
17NUMIx4 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
18Physics to be measured _at_ STAGE 2
All 3-type of measurements require nm anti-nm
beam
193 scenarios based on latest solar oscillation
observations
HLAM LMA
NLMA
Vacuum
20Assumed 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
21Compare 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!
22Anti-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)
23First 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.
24NLMA Pure ?µ??e due to atmospheric parameters
probability smaller for inverted hierarchy
CP-odd phase not observable but Ue32
measurements independent of phase
25NLMA 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
26NLMA Assume just 100kton/yrs forget about
anti-neutrino running if JHF exist for Hierarchy
27NLMAPD (120300kTon years) Hierarchy ?CPT more
important !
Is ?m2 the same?
Assumed solution
28 Look at High LMA? HLMA
- Assume atmospheric parameters to be know
- to 1
- Assume positive hierarchy
29 HLMAPD Confusion between Ue32 ? d, Dm2 12
Uncertainty in Dm212 gives extra tails
30LastLook at LMA
- Assume hierarchy to be positive
- Assume atmospheric parameters to be
- known to 1
31LMAPD 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
32LMAPD Assume a measurement is performed with
given luminosity ?µ??e events are seen
Assumed value of Ue3 2
Other cases
33Using 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)
34In 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)?
352 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 ?
36Conclusions 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