Neutrino telescopes as a direct probe of supersymmetrybreaking Page: 3 of 4
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actions in the earth, the NLSP pair should range into the
detector, just as the muons produced by CC events .
Charged particles lose energy due to ionization processes
as well as through radiation. The average energy loss is
given by 
d = a(fry) + c(#y) j3 , (4)
here a and c characterize the ionization and radiation
losses respectively, and are slowly varying functions of
the energy. The ionization loss can be approximated by
a(-y) ~ 0.08 MeV cm (17+ 2 ln)Q),
nd is rather independent of the particle mass. On the
other hand, assuming c(fy) ~ const., the radiative en-
ergy loss can be written as c )y (bm)E. Thus
b m b7Rm#R, and the radiative energy loss for the
NLSPs scales inversely with the mass. This results in
a much larger range for the NLSP as compared to the
muon. Current bounds on m7 are just above 100 GeV.
As a reference value we take m# - 150 GeV. Therefore,
NLSPs produced hundreds, even thousands of kilometers
away are within range of the detector. This is to be con-
trasted with the fact that muons must be produced at
distances not larger than tens of kilometers from the de-
tector in order to be observed. As we will see, this will
somewhat compensate the suppression of the SUSY cross
sections observed earlier.
Signals in Neutrino Telescopes In order to compute
the event rates in neutrino telescopes, we need to know
the incoming neutrino flux. The presence of cosmic neu-
trinos is expected on the basis of the existence of high
energy cosmic rays. Several estimates of the neutrino
flux are available in the literature. In most cases, it is
expected that km3 neutrino telescopes will measure this
flux. Here, in order to present projections for the number
of observed SUSY events, we make use of the Waxman-
Bahcall (WB) limit  as an estimate of the cosmic neu-
trino flux. We consider an initial flux containing both v
and ve (in a 2 : 1 ratio). Since the initial interactions (see
Figure 1) produce tL and these are nearly degenerate in
flavor, the flavor of the initial neutrino does not affect
our results. For the same reason, the possibility of large
mixing in the neutrino flux is also innocuous here. In
order to correctly take into account the propagation of
neutrinos and the NLSP tR through the earth, we make
use of a model of the earth density profile as detailed in
In Figure 3 we show the energy distribution for the
NLSP pair events for three choices of squark masses:
300 GeV, 600 GeV and 900 GeV. Also shown are the
neutrino flux at earth in the WB limit, as well as the en-
ergy distribution of upgoing p's. We see that, even for the
heavier squarks, it is possible to obtain observable event
6 7 8 9 10 11
10 10 10 10 10 10
FIG. 3: Energy distribution of TR pair events per km2, per
year. From top to bottom: mq = 300, 600 and 900 GeV.
Here, m, -150 GeV and m, - 250 GeV. Also shown are the
neutrino flux at earth and the p flux through the detector. In
all cases we make use of the WB limit for the neutrino flux.
TABLE I: Number of events per km2 per year for the WB
and MPR fluxes. The first column refers to upgoing muons.
The last three columns correspond to upgoing NLSP pair
events, for three different choices of squark masses: 300 GeV,
600 GeV and 900 GeV. The number of muon events are given
for energies above threshold for production of a 250 GeV PL
plus a 300 GeV squark, ie, 1.6 x 105 GeV.
p m = 300 GeV 600 GeV 900 GeV
WB 106 4 1 0.5
MPR 1085 10 3 1
rates. In Table I we show the event rates for fR pair pro-
duction per year and per km2. The rates are given for the
WB flux as well as for the Mannheim-Protheroe-Rachen
(MPR) flux , both for optically thin sources. For com-
parison, we also show the rates of upgoing muons. Thus,
km3 Cerenkov detectors such as ICECUBE, appear to
be sensitive to most of the parameter space of interest in
scenarios with a relatively long lived NLSP.
Since the NLSPs are produced in pairs very far from
the detector and with a very large boost, typical signal
events consist of two tracks separated by 6R ~ L 0, with
L the distance to the production point (~ 100-1000 Km)
and 0 ~ psy/pboost ~ 10-3 10-4. If we consider L
to be of the order of the NLSP range, then in the lin-
ear regime 6R ~ constant ~ 100m. As we have seen in
the discussion following eqn. (5), for very high energies
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Albuquerque, Ivone; Burdman, Gustavo & Chacko, Z. Neutrino telescopes as a direct probe of supersymmetrybreaking, article, December 15, 2003; Berkeley, California. (digital.library.unt.edu/ark:/67531/metadc779885/m1/3/: accessed September 19, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.