1/22

Possible constraints on New Physics
from matter effects on neutrino oscillations
Prepared by Minako Honda (Ochanomizu Univ.)
Presented by Tatsu Takeuchi (Virginia Tech)
withNaotoshi Okamura (YITP)
Alexey Pronin (Virginia Tech)
Yee Kao (Virginia Tech)
hep-ph/0602115, hep-ph/0603268, hep-ph/0607XXX
第１９回「宇宙ニュートリノ」研究会
2006.7.6 @ ICRR

2/22

Can interactions between neutrinos and matter
due to New Physics have any effect onneutrino oscillations?

beamCan such effects be measured experimentallyand be used to constrain New Physics?3/22

0. Introduction
Matter effectbeam

In a number of models beyond the SM,
the universality of thecouplings
can be violated through radiative corrections.

(a) charged current interactionex) MSSM withprocesses(b) neutral current interaction

etc...

lead to the violation of universality

4/22

νLi

λijkeRk

ν

Liλ′ijkd˜
Lje˜
Lje
Rk

λijkdRk

ν

LidRk

λ′ijk

ν

Li

New Physics that can contribute to neutrino oscillations:• R-parity violating couplings• Gauged B-αLe-βLμ-γLτ
(α+β+γ=3)• Z’ in Topcolor assisted Technicolor• Leptoquarks that couple different generations• etc.

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The experimental constraints
on universality violation in NC
from LEP
invisible

LEP/ OPAL, DELPHI,
L3, ALEPH, SLD

NO CONSTRAINT

No information is available
on the individual decay widths into each flavor

6/22

The experimental constraints
on universality violation in NC
from CHARM, CHARM II@ CERN (’80s)
cf ) Z couplings to charged leptons

Z couplings to neutrinos

0.9-1.2
PLB180,303(1986), PLB320,203(1994)( LEP invisible width

LEP/ OPAL, DELPHI,
L3, ALEPH, SLD)

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The theoretical possibilityof universality violation in many models
The weaknessof the current experimental bounds
CHARM, CHARM II

PLB180,303(1986),
PLB320,203(1994)

It would be interesting
to analyze the effect ofsuch a violation on neutrino oscillations.

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Plan of Talk
• Introduction• Matter effect– effective potentials for neutrinos in matter• W and Z exchange– effective hamiltonianin the presence of neutral current (NC) universalityviolation• Numerical results• A hypothetical experimentFermilab NuMI beam
⇒ Hyper-Kamiokande detector (1Mt)• Constraints on New Physics• Summary1-1. The effective potentials due toW & Z exchange
charged current interactionin ordinary matter

neutral current interaction

9/22

10/22

1-2. The effective Hamiltonianin the presence of NC universality violation： MNS matrix

CCNC

derived from universality violationin Neutral Current interaction
central valueof CHARM: measure of universality violation in NC： effective mixing matrix： effective mass-squares

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3. Numerical Results

12/22The energy dependenceof the effective mass squared differences

normal hierarchy

inverted hierarchy

neutrino beam energy [ GeV ]neutrino beam energy [ GeV ]The energy dependenceof the effective mixing angles

normal hierarchy

inverted hierarchy

neutrino beam energy [ GeV ]neutrino beam energy [ GeV ]13/22

14/22The oscillation probabilities ( L=9,120km )normal hierarchy

inverted hierarchy@17GeV@17GeV40%

40%neutrino beam energy [ GeV ]neutrino beam energy [ GeV ]15/22In the casethe oscillation probabilities ( L=9,120km )normal hierarchy

inverted hierarchy

Please refer to our paperfor details

neutrino beam energy [ GeV ]neutrino beam energy [ GeV ]16/22The oscillation probabilities ( L=9,120km )normal hierarchy

inverted hierarchy@17GeV@17GeV40%

40%neutrino beam energy [ GeV ]neutrino beam energy [ GeV ]17/22

Can these shifts
be measured experimentally ??

18/22Fermilab (NuMI)
Hyper-Kamiokande[ L~9,120 km ] (1Megaton detector)
HK (1Mt)
9,120km@17GeV

NuMI Beam Lines~732x12

Main Injector @ Fermilab

We can expect
a non-negligible
event rate

MINOS
@Soudan732km

no oscillation

Fermilab@17GeVeven when oscillation
is taken into account19/22The expected number ofevents @ HK
after 5years of data taking
4000

number of events

3500
3000
2500
2000

17GeV

1500

@ oscillation dip

1000

We can expect the green line
to be clearly distinguishable
from the blue or pink lines.

500
00

5

101520neutrino beam energy [ GeV ]2530

20/22The constrains on universality violation
100
80
60

10years

muchtightertighterconstraints
constraints
muchthanthat
thatfrom
fromthanCHARMandandCHARMIICHARMII
CHARM

5years
3years1year

40
99%C.L.

20
095%C.L.
90%C.L.

-0.03 -0.025 -0.02-0.01

00.02 0.025 0.03

0.01
~0.005~0.0151%

3%

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Constraints on New Physics
Leptoquarks that couple 1st and 2nd generations
S : scalar, V : vector, subscript : dim of SU(2) rep.

22/22

Summary
We investigated the matter effect on neutrino oscillationfrom universality violation in neutral current interactions.
The violation effectsnormal

inverted

mixing angle
oscillation probability
L=9,120 km
17GeV¾This result is highly sensitive to the value of¾If

Fermilab ⇒ Hyper-Kamiokande
is NOT too close to 1,
we may be able to either observe this effect, or
impose a much tighter constraint on universality violation
than that from CHARM and CHARMII.