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The Many Uses of Upward going Muons in Super-K

Muons traveling up into Super-K from high-energy n m reactions in the rock below provide a high-energy insight into many different problems.

Alec Habig, Univ. of Minnesota Duluth for the Super-K Collaboration

Upward-going

m S K • High energy n m can interact in rock some distance away and still produce a m seen by detector – Higher energy particles, more range, more effective volume!

– Increasing target mass at high E offsets falling n m spectra • Down-going entering cosmic ray muons restrict this technique to upward-going entering muons SK SK m m Stop m Through m n m n m Alec Habig Page 2 Neutrino 2002, May 25-30, Munich

S K Neutrino 2002, May 25-30, Munich

Up-

m

’s in Super-K

• For “SK I ” – 4/96 to 7/01 • 1678 live-days up thru (1657 up stop) – More than other SK analyses, this one is insensitive to poor detector conditions • For >7m path (>1.6 GeV): – 1878 thru m – 456 stop m Page 3 Alec Habig

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Atmospheric

n m Thru m data Stop m data No-osc MC

(best norm.)

Osc. MC Alec Habig • Up m flux is presented as a function of cos q and thus baseline – cos q =-1 (Up) have L~10,000 km – cos q =0 (Horizontal) have L~500 km • Lower E, longer L n ’s oscillate more • The data match the oscillated MC far better than the non oscillated MC – sin 2 2 q =1.0, D m 2 =2.7x10

-3 Page 4 Neutrino 2002, May 25-30, Munich

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Energy Lever Arm

• For n m seen as up m : – Typical E n ~ 10 GeV for stop m ,~ 100 GeV for thru m – Compare to contained event energies ~ GeV – From the soft atmospheric n spectrum. A harder n spectrum would produce a larger fraction of high energy parent n • Disadvantage – for any single event, the parent n energy is known only to be larger than the observed m energy Alec Habig Page 5

S K 90% C.L.

FC,PC Alone With up m Neutrino 2002, May 25-30, Munich n m

,

n t

Oscillation

• Even with comparatively small statistics and lousy energy resolution, the observation of n m disappearance at higher energies further refines the oscillation fit • Left – 90% C.L. contours with and without up m data • Best fit (

physical region

)*: – sin 2 2 q – D m 2 = 1.0

= 2.5x10

-3 *(

absolute best fit slightly unphysical at sin 2 2

q

=1.03

) Page 6

S K Neutrino 2002, May 25-30, Munich n m

to

n

sterile ?

• High energy n experience matter effects which suppress oscillations to sterile n – Matter effects not seen in up m or high-energy PC data – Reduction in neutral current interactions also not seen – constrains n s n m component of disappearance oscillations • Pure n m n s – n s disfavored fraction < 20% at 90% c.l.

Alec Habig Page 7

Unusual Models

S K Mode n m n t sin 2 2 q sin 2 (1.27

D m 2 L/E) n m n e ~sin 2 2 q sin 2 (1.27

D m 2 L/E) n m n s ~sin 2 2 q sin 2 (1.27

D m 2 L/E) LxE (L.I. violation) sin 2 2 q sin 2 ( a LxE) n m decay (short t ) sin 4 q +cos 4 q (1-e a L/E ) n m decay (long (sin 2 q +cos 2 q e t a ) L/2E ) 2 n m decoherence 0.5sin

2 2 q (1-e g L/E ) Null Hypothesis Best Fit sin 2 2 q =1.00

D m 2 =2.1x10

-3 sin 2 2 q =0.97

D m 2 =5.1x10

-3 sin 2 2 q =0.98

D m 2 =2.9x10

-3 sin 2 2 q =0.90

a =5.6x10

-4 cos 2 q =0.50

a =3.7x10

-3 cos 2 q =0.33

a =1.2x10

-2 sin 2 2 q =0.98

g =7.3x10

-3 c 2 173.8

284.3

222.7

281.6

279.4

194.0

184.3

427.4

Neutrino 2002, May 25-30, Munich P( c 2 ) 79% .001% 5% .002% .003% 41% 64% 0% Dc 2 0.0

110.5

48.9

107.8

105.6

20.2

10.5

252.4

Alec Habig s 0 s 10.5

s • Alternative ways to make n m disappear without invoking standard n m , n t flavor oscillations include – Lorentz invariance violation 7.0

s – Neutrino decay, decoherence 10.4

s 10.3

s 4.5

s • Fits using all available SK up m , 190 d.o.f.) strongly constrains many such models n data (FC+PC+NC+multiring+ 3.2

s 15.9

s – Hard for a model to get a good fit over 5 orders of magnitude in energy and 4 in baseline – Long t n m decay and n m decoherence disfavored but not eliminated

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Galactic Atmospherics?

• Cosmic rays interact with interstellar medium as well as our atmosphere – Would also produce n • ISM most dense at low galactic latitudes – Do we see excess n in the galactic plane?

• A search for these n does not see this weak signal Neutrino 2002, May 25-30, Munich Alec Habig Page 9

Astrophysical

n S K • • A hard n n spectrum: more likely a n signal will be seen as up m space-time coincidences with GRBs not seen at any energy in SK • AGNs or other astrophysical sources would produce point sources of high-energy n – All sky searches for such point-sources are negative – Unbinned searches for unusual clustering of up m also negative Neutrino 2002, May 25-30, Munich Alec Habig Page 10

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Pick a Source, Any Source

• To test your favorite model of n production at some high energy astrophysical source: – Up m near sources counted, a sampling shown here – Expected count from atm.

n background calculated – No excess seen, flux limits computed Neutrino 2002, May 25-30, Munich Alec Habig Page 11

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WIMP Detection

K • WIMPs could be seen indirectly via their annihilation products (eventually n m ) if they are captured in a gravitational well • WIMPs of larger mass would produce a tighter n beam – Differently sized angular windows allow searches to be optimized for different mass WIMPs Page 12 Neutrino 2002, May 25-30, Munich Alec Habig

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WIMP Results

• The Sun, Earth, and Galactic center are potential WIMP traps • No excess of n are seen in any angular cone about them – Upper limit of WIMP induced n calculated – Varies as a function of possible WIMP mass – Lower limits for higher masses are due to the better S/N in smaller angular search windows Alec Habig Page 13

Probing for WIMPs

S K • Most model dependence in indirect searches lies in the cross-section – Most conservative limits are taken for other uncertainties • Direct-detection experiments also do not know cross-sections – Comparisons can be made between direct and indirect searches • Both spin-dependent (left) and spin-independent (right) WIMP nucleon interactions can be probed (

a la

Kamionkowski, Ullio,

et al

) Neutrino 2002, May 25-30, Munich Alec Habig Page 14

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Summary

K • The high-energy end of the n m spectrum observed by Super-K is seen as up-going m • The extra lever arm in energy contributes to oscillation parameter estimation out of proportion to the small statistics and poor energy resolution of the sample • The high parent n energies allow probes of unusual areas of physics and astrophysics – Nothing unexpected seen, unfortunately Neutrino 2002, May 25-30, Munich The presenter gratefully acknowledges support for this poster from the National Science Foundation via its RUI grant #0098579, and from The Research Corporation’s Cottrell College Science Award