Indirect detection of supersymmetric particles with neutrino...
Transcript of Indirect detection of supersymmetric particles with neutrino...
Introduction Iteractions Direct Indirect Conclusions
Indirect detection of supersymmetric particles with
neutrino telescopes
Jairo C. de Souza
University of Sao Paulo – Brazil
TeVPA 2010
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Introduction Iteractions Direct Indirect Conclusions Particle Physics Gravitino LSP Scenarios
Starting point:
Neutrino Telescopes as a Direct Probe of Supersymmetry Breaking,Ivone. F. M. Albuquerque, Gustavo Burdman and Z. Chacko, PhysicalReview Letters, 92, 221802 (2004);
Direct detection of supersymmetric particles in neutrino telescopes, Ivone.F. M. Albuquerque, Gustavo Burdman and Z. Chacko, Physical Review D75, 035006 (2007);
Jairo C. de Souza Indirect detection of supersymmetric particles Slide: 2
Introduction Iteractions Direct Indirect Conclusions Particle Physics Gravitino LSP Scenarios
Starting point:
Neutrino Telescopes as a Direct Probe of Supersymmetry Breaking,Ivone. F. M. Albuquerque, Gustavo Burdman and Z. Chacko, PhysicalReview Letters, 92, 221802 (2004);
Direct detection of supersymmetric particles in neutrino telescopes, Ivone.F. M. Albuquerque, Gustavo Burdman and Z. Chacko, Physical Review D75, 035006 (2007);
Goal
Extend the results for a complementary Supersymmetry Breaking Energy Scale:
107GeV .√F . 1010GeV −→ 105GeV .
√F . 107GeV
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Introduction Iteractions Direct Indirect Conclusions Particle Physics Gravitino LSP Scenarios
Outline
Theoretical context;
Interactions – cross sections, energy loss and ν flux;
What was already done – study of the direct detection of the NLSPssignals;
What is new – study of the indirect detection of the NLSPs signals.
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Introduction Iteractions Direct Indirect Conclusions Particle Physics Gravitino LSP Scenarios
Introduction
Weak scale supersymmetry (SUSY) as an extension of the StandardModel of particle physics;
R-parity → neutral and stablelightest supersymmetric particle (LSP);
The supersymmetry must be broken →√F :
If√F . 1010GeV → Gravitino LSP;
If√F & 1010GeV → Neutralino LSP.
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Introduction Iteractions Direct Indirect Conclusions Particle Physics Gravitino LSP Scenarios
Gravitino LSP Scenarios
Processes that have to be considered:
νN → lLq
lLq promptly decay to 2lR + SM particles
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Introduction Iteractions Direct Indirect Conclusions Particle Physics Gravitino LSP Scenarios
Gravitino LSP Scenarios
Processes that have to be considered:
νN → lLq
lLq promptly decay to 2lR + SM particles
lR : typically the τR → Next to lightest supersymmetric particle (NLSP);
τR lifetime can be very large → can travel very long distances beforedecaying:
cτ =( √
F
107GeV
)4 (100GeVmτR
)5
10 km
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Introduction Iteractions Direct Indirect Conclusions Particle Physics Gravitino LSP Scenarios
Gravitino LSP Scenarios
Processes that have to be considered:
νN → lLq
lLq promptly decay to 2lR + SM particles
lR : typically the τR → Next to lightest supersymmetric particle (NLSP);
τR lifetime can be very large → can travel very long distances beforedecaying:
cτ =( √
F
107GeV
)4 (100GeVmτR
)5
10 km
107GeV .√F . 1010GeV ⇒ direct detection (τR doesn’t decay inside
the Earth);
105GeV .√F . 107GeV ⇒ indirect detection (τR decays inside the
Earth).
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Introduction Iteractions Direct Indirect Conclusions Cross-sections Energy loss ν Flux
ν-nucleon cross-sections
10-36
10-35
10-34
10-33
10-32
106
107
108
109
1010
1011
Eν (GeV)
σ (c
m2 )
The three lower curves correspond to mℓL
= 250 GeV, mw = 250GeV; and for squark masses mq = 300 GeV
(dashed) , 600 GeV (dot-dashed) and 900 GeV (dotted). The top curve corresponds to the SM charged currentinteractions and the middle one to the di-muon background.
Figure: I. F. M. Albuquerque, et al, Physical Review D 75, 035006 (2007).
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Introduction Iteractions Direct Indirect Conclusions Cross-sections Energy loss ν Flux
Energy loss for muon and stau
Three main contributions – bremsstrahlung, pair production and photonuclear
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
x 10-5
104
105
106
107
108
109
pair
Eµ (GeV)
b (c
m2 /g
)
bremph nuc
10-13
10-12
10-11
10-10
10-9
10-8
10-7
106
107
108
109
1010
1011
pair
Estau (GeV)
b (c
m2 /g
)
bremph nuc
Figures: M. H. Reno, I. Sarcevic and S. Su, Astroparticle Physics 24, 107 (2005); Ivone F. M. Albuquerque, et al,
Physical Review D 75, 035006 (2007).
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Introduction Iteractions Direct Indirect Conclusions Cross-sections Energy loss ν Flux
Neutrino flux
Waxman and Bahcall (WB) limit – the
observed cosmic ray flux implies an upper
bound on the high energy astrophysical
neutrino flux.
(
dφν
dE
)
WB= (1−4)×10−8
E2
GeV cm−2s−1 sr−1
Mannheim, Protheroe and Rachen (MPR)
limit – upper limit on the diffuse neutrino
sources.
10-18
10-17
10-16
10-15
10-14
10-13
105
106
107
108
109
1010
1011
Eν (GeV)
E d
Φν/
dE (
cm-2
s-1sr
-1)
WB limit
MPR limit (transparent sources)
MPR limit (opaque sources)
Figure: I. F. M. Albuquerque et al, arXiv:0803.3479v1[hep-ph]
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Introduction Iteractions Direct Indirect Conclusions Energy spectrum Track separation
Direct detection
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Introduction Iteractions Direct Indirect Conclusions Energy spectrum Track separation
Direct detection – Energy spectrum
lR pair events per km2, per year, at the
detector. Curves that do not reach y
axis; from top to bottom: mq = 300,
600 and 900 GeV. Here,
mlR
= 150 GeV and mw = 250 GeV.
Also shown are the neutrino flux at
earth and the µ and the di-muon flux
through the detector (curves that reach
y axis; from top to bottom
respectively). In all cases we make use
of the WB limit for the neutrino flux.
Figure: I. F. M. Albuquerque, et al,
Physical Review D 75, 035006 (2007).
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Introduction Iteractions Direct Indirect Conclusions Energy spectrum Track separation
For track separations above 100 m there should not be any significant contribution from the di-muon background.
00.10.20.30.40.50.60.70.80.9
1
0 100 200 300 400 500 600track separation (m)
dist
ribu
tion
stau (300)stau (600)stau (900)
0123456789
10
0 20 40 60 80 100 120 140 160 180 200track separation (m)
dist
ribu
tion
µ+µ-
The relative normalization corresponds to the relative number of events for signal and background. Note thedifferent horizontal scales, as well as different binning between the two figures.
Figure: I. F. M. Albuquerque, et al, Physical Review D 75, 035006 (2007).
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Introduction Iteractions Direct Indirect Conclusions Interactions τ at IceCube (s)tau at Euso
Indirect detection of NLSPs
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Introduction Iteractions Direct Indirect Conclusions Interactions τ at IceCube (s)tau at Euso
Indirect detection of NLSPs
Now: considering the τ decay
τ decay −→ τ + gravitino
τ regeneration:
τ decay −→ ντ + X
ντ Ncc−→ τ + X
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Introduction Iteractions Direct Indirect Conclusions Interactions τ at IceCube (s)tau at Euso
τ survival probability (decay)
x (m)-610 -510 -410 -310 -210 -110 1 10 210 310 410 510 610
τ∼P
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
GeV 4 = 10F
GeV 5 = 10F
GeV 6 = 10F
GeV7 = 10F
GeV6 10× = 5 νE
Different√F (energy fixed).
x (m)1 10 210 310 410 510 610 710 810 910 1010
τ∼P
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
GeV 6 10×E = 5
GeV 8E = 10
GeV 9E = 10
GeV11E = 10
GeV6 10× = 1 F
Different energies (√F fixed).
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Introduction Iteractions Direct Indirect Conclusions Interactions τ at IceCube (s)tau at Euso
IceCube
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Introduction Iteractions Direct Indirect Conclusions Interactions τ at IceCube (s)tau at Euso
IceCube
τ energy at the detector and number of τ regenerations
Entries 141790Mean 4.756RMS 0.4387
(GeV))τν
Log10(E2 3 4 5 6 7 8
Eve
nts
0
0.2
0.4
0.6
0.8
1
Entries 141790Mean 4.756RMS 0.4387
GeV510× = 1F -- τ
= 300 GeVq~ at detector -- mτE
(GeV)νE610 710 810 910 1010 1110
Reg
ener
atio
ns
3
4
5
6
7
8
9
GeV510× = 1F
GeV610× = 1F
GeV610× = 5F
that reach the detectorτRegenerations --
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Introduction Iteractions Direct Indirect Conclusions Interactions τ at IceCube (s)tau at Euso
τ ’s flux atIceCube
∼ 10−6
events
× km−2 ×year−1
(GeV)νE
610 710 810 910 1010 1110
)-1
.y-2
(km
νdN
/dE
νE
-1410
-1210
-1010
-810
-610
-410
-210
1
210
410
-- 29 710× = 5F : genτ∼
-- 6 710× = 5F : detτ∼
-610× -- 1510× = 1F : detτ
-710× -- 9610× = 1F : detτ
-710× -- 2610× = 5F : detτ
WB flux
= 300 GeVq~ -- mν E×Events
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Introduction Iteractions Direct Indirect Conclusions Interactions τ at IceCube (s)tau at Euso
Euso (∼ 2× 105 km2)
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Introduction Iteractions Direct Indirect Conclusions Interactions τ at IceCube (s)tau at Euso
Euso (∼ 2× 105 km2)
τ and τ at the atmosphere
(GeV)νE
610 710 810 910 1010 1110
)-1
.y-2
(km
νdN
/dE
νE
-610
-510
-410
-310
-210
-110
1
10
210
310
410
510
610 Gen = 29τ∼ TotalAtm = 6.1τ∼ NotDecay = 1.8τ∼ DecayAtm = 1.3τ∼
WB Fluxν
GeV610× = 5F
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Introduction Iteractions Direct Indirect Conclusions Interactions τ at IceCube (s)tau at Euso
Euso (∼ 2× 105 km2)
τ and τ at the atmosphere
(GeV)νE
610 710 810 910 1010 1110
)-1
.y-2
(km
νdN
/dE
νE
-610
-510
-410
-310
-210
-110
1
10
210
310
410
510
610 Gen = 29τ∼ TotalAtm = 6.1τ∼ NotDecay = 1.8τ∼ DecayAtm = 1.3τ∼
WB Fluxν
GeV610× = 5FProblem: air fluorescence
is related to the number
of charged particles (Ne):
dNdx
= NfNe ,
Nf ∼ 4.8 photons × m−1
× (charged particle)−1
Ne = 1, 2 (τ case)
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Introduction Iteractions Direct Indirect Conclusions Interactions τ at IceCube (s)tau at Euso
Checking the τ
produced at theatmosphere:
(GeV)νE
610 710 810 910 1010 1110
)-1
.y-2
(km
νdN
/dE
νE
-610
-510
-410
-310
-210
-110
1
10
210
310
410
510
610 Gen = 29τ∼
BothDecayAtm = 0.15τ∼
TotalDecayAtm = 1.3τ∼
WB Fluxν
GeV610× = 5F
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Introduction Iteractions Direct Indirect Conclusions Interactions τ at IceCube (s)tau at Euso
Checking the τ
produced at theatmosphere:
Flux with a goodnumber of detectableshowers:
∼ 3 × 104
events × year−1
for the coincidence
case.
(GeV)νE
610 710 810 910 1010 1110
)-1
.y-2
(km
νdN
/dE
νE
-610
-510
-410
-310
-210
-110
1
10
210
310
410
510
610 Gen = 29τ∼
BothDecayAtm = 0.15τ∼
TotalDecayAtm = 1.3τ∼
WB Fluxν
GeV610× = 5F
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Introduction Iteractions Direct Indirect Conclusions Interactions τ at IceCube (s)tau at Euso
τ pair decaying coincidently at the atmosphere
Distance between showers ⇒ distinguishable signal with acceptable timming.
Entries 48540
Mean 191.6
RMS 108.2
Distance between staus (km)0 100 200 300 400 500 600
Eve
nts
0
0.2
0.4
0.6
0.8
1
Entries 48540
Mean 191.6
RMS 108.2
GeV 610× = 5F Entries 48540
Mean -6.363
RMS 0.2658
log10(time(s))-8 -7.5 -7 -6.5 -6 -5.5 -5
Eve
nts
0
0.2
0.4
0.6
0.8
1Entries 48540
Mean -6.363
RMS 0.2658
GeV 610× = 5F
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Introduction Iteractions Direct Indirect Conclusions Interactions τ at IceCube (s)tau at Euso
But, there is still aproblem:
Entries 2577530
Mean 4.91
RMS 0.5064
log10(E(GeV))1 2 3 4 5 6 7 8 9
Eve
nts
0
0.2
0.4
0.6
0.8
1
Entries 2577530
Mean 4.91
RMS 0.5064
Atmτ∼ GeV6 10× = 5 F
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Introduction Iteractions Direct Indirect Conclusions Interactions τ at IceCube (s)tau at Euso
But, there is still aproblem:
The (s)tau energyat the atmosphereis too low whencompared with thedetector threshold.
Entries 2577530
Mean 4.91
RMS 0.5064
log10(E(GeV))1 2 3 4 5 6 7 8 9
Eve
nts
0
0.2
0.4
0.6
0.8
1
Entries 2577530
Mean 4.91
RMS 0.5064
Atmτ∼ GeV6 10× = 5 F
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Introduction Iteractions Direct Indirect Conclusions
Conclusions
The flux of τ (from τ) at IceCube is too low. So, if the√F is
lower than ∼ 107 GeV, the NLSP detection with this detectorit is not possible;
The number of showers produced at the atmosphere is enoughfor a detector with an area like the Euso’s. The limitation isthe energy threshold. Maybe a different experiment?
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Introduction Iteractions Direct Indirect Conclusions
Thanks!
Jairo C. de Souza Indirect detection of supersymmetric particles Slide: 20