sergio palomares-ruiz june 8, 2005 ls n d imits olutions ew iscoveries et’s peak about lsnd...
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Sergio Palomares-Ruiz
June 8, 2005
L S N Dimitsolutionsewiscoveries
et’speak about LSNDeutrinos inelphi
WIN’0520th International Workshop on Weak Interactions and
Neutrinos Delphi, Greece, June 6-11, 2005
The
Anomaly
Sergio Palomares-Ruiz
June 8, 2005
THE FACTS
Sergio Palomares-Ruiz
June 8, 2005“Non Standard” results
Solar neutrino deficit8 σ effect
Atmospheric neutrino anomaly14 σ effect
Neutrino disappearance
m221 = (7.3 - 9.1) 10-5 eV2
sin2 12 = (0.23 – 0.37)
| m231| = (1.4 – 3.3) 10-3 eV2
sin2 223 > 0.90
Neutrino OscillationsHomestake, SAGE, GALLEX,
SK, SNO + KamLANDSK and K2K
Standard results
sin2 13 < 0.047
M. Maltoni et al., New J. Phys. 6:122, 2004
Sergio Palomares-Ruiz
June 8, 2005“Standard” results
• Bugey (e → e) L = 15 m , 40 m, 95 m; E ~ few MeV → m2 ~ 0.01 – 1 eV2
• CHOOZ and Palo Verde (e → e) [for 13 small] L ~ 1000 m; E ~ few MeV → m2 ~ 10-3 eV2
• CCFR ( → ) L = 0.715 km and 1.116 km (2 detectors) 40 GeV < E < 230 GeV → m2 ~ 10 – 100 eV2
• CDHS ( → ) L = 0.130 km and 0.835 km (2 detectors) E ~ GeV → m2 ~ 1 – 100 eV2
No neutrino disappearance
Sergio Palomares-Ruiz
June 8, 2005“Standard” results
• NOMAD ( → e)
L = 0.635 km; 1 GeV < E < 100 GeV → m2 ~ 1 – 100 eV2
• KARMEN ( → e)
L = 17.6 m; 16 MeV < E < 50 MeV → m2 ~ 0.1 – 10 eV2
No neutrino appearance
So far, so good!
No short baseline neutrino “anomaly”Neutrino anomalies explained by oscillationsbetween 3 neutrinos → 2 independent m2
Sergio Palomares-Ruiz
June 8, 2005
• LSND ( → e)
L = 30 m; 20 MeV < E < 52.8 MeV → m2 ~ 1 – 10 eV2
It did see e appearance!
Non-Standard resultNeutrino appearance
But…
m2atm + msol m2
LSND
Sergio Palomares-Ruiz
June 8, 2005The LSND experiment
A. Aguilar et al., Phys. Rev. D64:112007, 2001
Neutrinos are produced from pion and muon decays
+ → + (e+ e) - → - (e- e)
+ → e+ e - → e- e e
Most + decay at rest (97%) and also most + Very few - decays at rest (DAR) → 0.08% e backgrounds
Sergio Palomares-Ruiz
June 8, 2005
3.3 σ effect
A. Aguilar et al., Phys. Rev. D64:112007, 2001 G. Drexlin, Nucl.Phys.Proc.Suppl.118:146-153,2003
e excess : 87.9 ± 22.4 ± 6.0
P ( → e ) = (0.264 ± 0.067 ± 0.045) %
Sergio Palomares-Ruiz
June 8, 2005
THE ESPECULATIONS
Sergio Palomares-Ruiz
June 8, 2005Classifying solutions
• With and without sterile neutrinos – With one and with more than one sterile
• With and without neutrino oscillations• With and without CPT violation• With non-standard and with standard processes• With and without extra dimensions• With problems and with problems• Those we like and those we don’t like• Those we have proposed and those we haven’t
proposed• No solution
But if LSND is right, all imply NEW PHYSICS!
Sergio Palomares-Ruiz
June 8, 20054 neutrino models
24
24 LSND
2
24
24 CDHS
2
24
24BUGEY
2
4 2sin
)1(4 2sin
)1(42sin
UU
UU
UU
e
ee
2+2 3+1
m2sol m2
sol
m2atm
m2atm
m2LSND
m2LSND
e
s
Steriles would participate in solar and atmospheric neutrino oscillations
Ruled out at 5.1 σ
Disfavored by SBL and atmospheric neutrino experiments
M. Maltoni et al., New J. Phys. 6:122, 2004
Sergio Palomares-Ruiz
June 8, 20053+2 neutrino models
m2sol
m2atm
m2LSND1
m2LSND2
M. Sorel, J. M. Conrad and M. H. Shaevitz, Phys. Rev. D66:033009,2002
Compatibility between SBL (including KARMEN) and LSND of 30%, instead of 3.6 % in the standard 3+1 model
Sergio Palomares-Ruiz
June 8, 2005CPT violating spectra
m2sol
m2atm
e
E
LmUU
E
LmUUPP eeeeee 4
sin44
sin)1(41)(2
atm222
21
2LSND22
323REACTOR
The killer: reactor experiments
Bugey and CHOOZ: need Ue3 ' 1
PKamLAND ' 1
m2atm
m2LSND
m2KamLAND
m2LSND,atm
H. Murayama and T. Yanagida, Phys. Lett. B520:263-268, 2001G.Barenboim, L. Borissov and J. Lykken, Phys.Lett.B534:106-113,2002
The killer: atmospheric experiments
… for LSND m2, antineutrinos signal would•wash out the up-down asymmetry •produce a deficit of up-going muon events near the horizon
Although there is someroom for CPT violationwith all-but-LSND data…
G. Barenboim, L. Borissov and J. Lykken, hep-ph/0212116A. Strumia, Phys. Lett. B539:91-101,2002M. C. González-García, M. Maltoni and T. Schwetz, Phys. Rev. D68:053007, 2003
Sergio Palomares-Ruiz
June 8, 2005
• 3+1 models - U 4 constrained by CCFR and atmospherics,
not CDHS → still some room - Ue4 constrained by GALLEX (e disappearance during test with a 51Cr source)
• 2+2 models Too little sterile content on solar and atmospheric neutrino oscillations → Ruled out• Hybrid models
•(3+1) , (2+2) : no bound from solar neutrino data•(3+1) , (2+2) : similar to (2+2) → excluded
4 neutrinos + CPT violationAssuming the same m2 for neutrinos and antineutrinos
but different mixings
V. Barger, D. Marfatia and K. Whisnant, Phys. Lett. B576:303-308,2003
Sergio Palomares-Ruiz
June 8, 2005
CPT violating decoherenceQuatum gravity models involve singular space-time configurations: space-time foam → decoherence is the result of particle propagation due to the fuzzy properties of the background not necessarily related to mass differences between particles and antiparticles
Simple model: effects only in the antineutrino sector and diagonal decoherence matrix → No spectral distortions at KamLAND
Without KamLAND With KamLANDG. Barenboim and N. E. Mavromatos, JHEP01:034, 2005
Pure decoherence Pure decoherence both
Mixing + decoherence Mixing + decoherence
both
Sergio Palomares-Ruiz
June 8, 2005
Lorentz violationIn the minimal Standard Model Extension (SME) with Lorentz violation, neutrinos are massless and oscillations are determined
by 102 real constants controlling the Lorentz violation
V. A. Kostelecký and M. Mewes, Phys. Rev. D69:016005, 2004
ppcpa
Eh LLeff )()(
1
P ( → e) ' |(heff)e|2 L2 → for LSND |(heff)e|2 ~ (3 x 10-19 GeV)2
V. A. Kostelecký and M. Mewes, Phys. Rev. D70:076002, 2004
Unusual dependences for the oscillation phases: aL L and cL L E
Predict, e.g., azimuthal dependence for atmospheric neutrinos
Constraints (in the - sector): aL < few 10-23 GeV cL < 10-24
M. C. González-García and M. Maltoni. Phys. Rev. D70:033010, 2004
aL ~ 10-19 GeVcL ~ 10-17
Sergio Palomares-Ruiz
June 8, 2005
LFV muon decay
)%045.0067.0264.0()( LSND PeBr e
The L = 2 decay: + → e+ + e + ( = e, , )
could explain LSND data if
Scale of new physics relatively low, ~ 300-400 GeV, → effects on low energy observables, e.g., the SM parameter in the Michel spectrum
These models predict = 0 for L = 2 decays → constrained by KARMEN BRKARMEN < 0.0017 (90% CL), but BRLSND > 0.0021 (90% CL)
B. Armbruster et al., Phys. Rev. Lett. 90:181804, 2004
K. S. Babu and S. Pakvasa, hep-ph/0204236
Predicted = 0.7485
TWIST experimentMeasured = 0.75080 ± 0.00032 ± 0.00097 ± 0.00023
J. R. Musser et al., Phys. Rev. Lett. 94:101805, 2005
Sergio Palomares-Ruiz
June 8, 2005
Mass varying neutrinos
N
Neffi n
mM i
2
Matter effects on neutrinos due to the interaction with a very light and weakly coupled scalar particle could give rise to masses and mixings which are enviroment dependent
Yukawa couplings
V()´´
Nucleon number density
•LSND, KamLAND, K2K and Palo Verde are in matter•Bugey and CHOOZ are in air•KARMEN is 50% in matter and 50% in air•CDHS is unknown
•It could accomodate 3+1 models: an experiment like Bugey but in matter should see disappearance•Limits for 2+2 models are very model dependent
D. B. Kaplan, A. E. Nelson and N. Weiner, Phys. Rev. Lett. 93:091801, 2004K. M. Zurek, JHEP 0410:058, 2004
Sergio Palomares-Ruiz
June 8, 2005
Shortcuts in extra dimesionsIn some theories with extra dimensions, SM particles propagate only in the brane, but non-SM particles can also do it in the bulk.If the brane is distorted → shortcuts
s travel “faster”
This induces an effective term in the hamiltonian which introduces resonant mixing driven by , the aspect ratio of the brane deformation
The key point: evading CDHS bounds by a resonance in the range 30 - 400 MeV
No effect No bound
If Eres ~ 30 – 100 MeV → no signal in MiniBooNEIf Eres ~ 200 – 400 MeV → impressive signature in MiniBooNEH. Päs, S. Pakvasa and T. J. Weiler hep-ph/0504096
Sergio Palomares-Ruiz
June 8, 2005
Neutrino oscillations + decay
The decay option: key ingredient to evade CDHS boundsFor small U4 and short baselines
3+1 model with a decay option…
…but LSND explained (mainly) by oscillations
3,2,14int gL
)1(21)2/(cos(121)( 24
24
)2/(24
44 DUELmeUP ELm
CDHS compares measurements at two detectors: if D1 = D2 , no difference
This requires 4 / m4 ~0.03-0.1 and m4 ~ few eV → g ~ 103 -104
In contradiction with laboratory bounds g < 10-2 E. Ma, G. Rajasekaran and I. Stancu, Phys. Rev. D61:071302, 2000
Sergio Palomares-Ruiz
June 8, 2005
Neutrino decay3+1 model with a decay option…
…but LSND explained by decay
3,2,143,2,14,
int and ..chngLhl
hRlLhl
N
Nhlll E
mgNN
32
||)()(
2
Good fit to data
SPR, S. Pascoli and T. Schwetz, hep-ph/0505216
As far as ge ´ Uel ghl 0 , we expect e and e appearance
Sergio Palomares-Ruiz
June 8, 2005
Mixing of e with 4 is not required → we set Ue4 = 0Only CDHS and atmospherics constrain the model
LSND and KARMEN compatibility
L
lATM
LSBL
eUPP
eUUP
4
4
4
4
4
4
22
4
)(
1)(
SPR, S. Pascoli and T. Schwetz, hep-ph/0505216
Sergio Palomares-Ruiz
June 8, 2005
The rate of N’s is controlled by U 4 and that of e’s by ghe
In order to be consistent with laboratory and supernova bounds, a typical value is g ~ 10-5
With -1 ~ LLSND (g m4 ~ 1 - 10 eV) → m4 ~ 100 keV
The MiniBooNE signalIn addition, extending the model with an extra neutrino and allowing for complex couplings, the signal in the neutrino run might be suppressed
SPR, S. Pascoli and T. Schwetz, hep-ph/0505216
Sergio Palomares-Ruiz
June 8, 2005
THE RIGHT ONE
Sergio Palomares-Ruiz
June 8, 2005
??
Sergio Palomares-Ruiz
June 8, 2005 Conclusions• Solar (8σ) and atmospheric neutrino (14σ)
anomalies well understood in terms of oscillations
• LSND: the only (anti)neutrino appearance experiment with positive signal (3.3σ)… why shouldn’t it be right?
• Many possible solutions…• … if LSND is right, (hopefully) one must be right• If so, we might need to forget about our
prejudices on sacred principles, modify the Standard Model of Cosmology…
• We all will have more fun!• If anyone is in a hurry…
Sergio Palomares-Ruiz
June 8, 2005
So we will wait for MiniBooNE!
Oracular responses were given every month, on the 7th day, the birthday of
Apollo
…we could ask to Delphi’s Oracle
Unfortunately…