Alexandre Kisselev

1
Extra dimensions and high energy cosmic neutrinos
Alexandre Kisselev Institute for High Energy
Physics Protvino, Russia
Xth International School-Seminar The Actual
Problems of Microworld Physics Belarus,
Gomel, July 23, 2009
2
Outlook
Spectrum of high energy cosmic rays (CRs)
?
Diffuse fluxes of cosmic neutrinos
?
Space-time with extra dimensions (EDs)
?
Neutrino-nucleon interactions in models with EDs
?
Neutrino telescopes
?
Quasi-horizontal air showers at Auger Observatory
?
Conclusions
?
3
CR spectrum
E lt 3?1014 eV energy region of atmospheric
neutrinos
Energy scale GeV TeV PeV EeV ZeV
4
GZK - cutoff of CR spectrum
(Greisen, Zatsepin, Kuzmin, 1967)
Attenuation length for proton scattering on
cosmic microwave background (CMB)
5
Data from AGASA and HiRes
AGASA number of events with E gt EGZK
HiRes observation of GZK-cutoff
6
Data from Auger
(Pierre Auger Coll., 2008)
Extrapolation of spectrum E-2.69 Expected number
of events with E gt 100 EeV 35 1 Number of
observed events 1
GZK -cutoff (6?)
7
Diffuse fluxes of cosmic neutrinos
Guaranteed GZK (cosmogenic) flux
?
Flux depends significantly on composition of
primary particles (proton- heavy nuclei)
Cosmic accelerators active galactic nuclei
(AGN), gamma-ray bursts (GRB),
?
Flux is sensitive to energy boundary between
galactic and extragalactic parts of CR spectrum
8
Active galactic nucleus (AGN)
9
Flavor ratio
(near neutrino source)
After neutrino oscillation
(near detector)
Bound on diffuse neutrino flux (all flavors,
1013 eV lt E? lt 1020 eV)
(Waxman Bahcall, 1999)
10
Top-down (TD) models (decays of super-massive
dark matter, topological defects, etc.)
?
Models are motivated by AGASA data
Domination of photons in CRs composition is
predicted
TD models are strongly disfavored by recent
data on gamma ray flux
Photon fraction in CR spectrum lt 3.8 , E gt
2 EeV
lt 11.7, E gt 10 EeV
(Pierre Auger Coll., 2008)
lt 1 , E gt 2 EeV
(Yakutsk Coll., 2009)
11
Detection of signals from cosmic neutrinos will
allow
to discover CR point sources and define their
position in the Universe
?
to understand mechanisms of CR acceleration
?
to define energy boundary between galactic and
extragalactic parts of CR spectrum
?
to measure cosmic neutrino flux, flavor ratio,
and neutrino-nucleon cross section ??N
?
SM ??N is small and rises slowly with energy
significant (dominating) contribution from new
physics is expected at high (ultra-high) energies
12
Extra dimensions with flat metric (ADD-model)
(Arkani-Hamed et al., Antoniadis, 1998)
n number of EDs
MPl - Planck mass MD - D-dimensional gravity
scale (D4n) R radius of EDs
13
Masses of Kaluza-Klein (KK) excitations
Interaction of gravitons with SM fields
Graviton life time
Spectrum stable spin-2 particles Main
signature missing mass
14
One extra dimension with warped metric (RS-model)
(Randall Sundrum, 1999)
AdS5 - space-time
r radius of ED (-? r ? y ? ? r) ? curvature
parameter
Masses of KK-gravitons
xi roots of Bessel function J1(x)
15

Gravity
TeV brane
Planck brane

SM
y 0
y ? r
16
Interaction Lagrangian
Small curvature
(Giudiche et al., A.K. Petrov, 2005)
Spectrum light KK resonances with mass splitting
?m ? ??
Standard RS scenario
heavy KK resonances (m11TeV)
17
Lower bounds on gravity scale MD
? Large extra dimensions (D 4n)
Production of gravitons, for instance
(Landsberg, 2008)
? One extra dimension with small curvature (n1)

M5 gt 1.7 TeV
(DELPHI Coll., 2006)
M5 gt 1.5 TeV
(A.K., 2008)
HERA
MS gt 0.9 TeV
(A. Geiser, talk at this School)
18
Scattering at trans-planckian energies
(Giudice et al., 2002 A.K. Petrov, 2005 )
eikonal approximation
Born amplitude is a sum of reggeized gravitons
(gravi-Reggeons) with trajectories
(trajectories are characterized by KK-number n)
?
?
?
?n
AB
n
i
i
19
Scattering of cosmic neutrinos off nucleons
RS model with small curvature (? 100 MeV)
M5 3 TeV 5 TeV 7 TeV
SM
(A.K., 2008)
MD 2 TeV
ADD model (n5) solid line thin brane dashed
line brane with tension (? 1/TeV)
SM
Sessolo McKay, 2008)
20
Production of microscopic black holes by cosmic
neutrinos (D gt 4)
(Argyres et al., 1998 Banks Fisher, 1999,
Emparan et al., 2000)
?(?N?bh) for n 1,2,7
Schwarzschild radius of black hole with mass
Mbh?s
MD 1 TeV
MD 1 TeV
SM
Life time lt 10-25 ??? (MD gt 1 TeV, Mbh lt 10 TeV)
solid lines Mbh(min) MD dashed lines
Mbh(min) 3MD
LHC ?bh 15 nb ? 1 pb, MD 1?5 TeV becomes
twice small, when n varies from 1 to 7
(14 TeV ? E? 108 GeV)
21
Neutrino telescope IceCube (to be completed in
2011)
AMANDA (all flavors)
IceCube (?? , one year of operation)
IceCube 80  strings 4800 modules 
IceTop 16 tanks 32  modules
Optimal energies 10 TeV 10 PeV
22
Baikal (NT200)
NT200 (2006), all flavors Veff 0.2 mt, 10 TeV
NT200 (3 year of operation) Veff 10 mt, 10 PeV
Gigatone detector (a project) Veff 0.5-1.0
km3, gt 100 TeV
23
Neutrino telescopes (Mediterranean Sea)
ANTARES (Toulon)
NEMO (Capo Passero)
KM3NeT (V 1 km3)
NESTOR (Pylos)
Optimal sensitivity - at energies E? gt 10 TeV
for the process
24
Detection of radio emission at the South Pole
(ANITA)
Acoustic and radio signals from electromagnetic
cascades (Askaryan, 1957, 1961)
Coherent radio emission exceeds (dominates over)
optical emission at E gt 10 PeV (1 EeV) (since it
rises E2)
1018.5 eV lt E? lt 1023 eV
25
Pierre Auger Observatory
Hybrid detector ? 1600 water
Cherenkov tanks arranged on area of 3000 km2 ? 24
fluorescence telescopes located at four sites
E gt 1018 eV
26
Registration of quasi-horizontal air showers
induced by cosmic neutrinos
(Berezinsky, Zatsepin, Smirnov, 1969/75)
For inclined showers produced in upper part of
atmosphere electromagnetic part of shower is
absorbed before reaching detector
E gt1019 eV muon component cutoff ? probability
of proton-induced deeply penetrating shower is lt
10-4
27
Event rate of air showers
effective detector area
neutrino flux
shower energy
detection efficiency
cross section
neutrino attenuation factor
y inelasticity (SM y 0.2?0.24)
28
? Extrapolation of SM cross sections
(Gandhi et al., 1998)
? Cross sections beyond SM
(Anchordoqui et al., 2006)
?z gt70?
Ratio of inclined air showers to showers
initiated by Earth-skimming ? -neutrinos
29
Expected number of neutrino induced
quasi-horizontal (?z gt75?) air showers (RS
scenario, 1 year of operation)
Expected number of events with black hole
production at Pierre Auger detector (ADD
scenario, 5 year of operation)
30
Experimental upper limits on diffuse neutrino
flux (converted to a single flavor)
Bound on ?-neutrino flux (Auger Coll., 2008)
31
Conclusions
We have
Cosmic neutrinos are not yet observed
?
Auger upper limit on diffuse neutrino flux ??
becomes rather close to guaranteed
GZK-neutrino flux
?
We expect
Present and future telescopes will be able to
detect signals from high energy cosmic neutrinos
in a few years
?
Detection of these signals ? nice possibility of
searching for ED effects (physics beyond SM, in
general)
?
Simultaneous registration of inclined showers and
Earth- skimming neutrinos allows us to estimate
both ?? and ??N
?
?
If no such events are observed ? limits on
multi-dimensional gravity scale comparable with
reach limits of the LHC
32
????? ?? ??????? ????? ???????. ?? ? ????, ????
??? ?????? , ?? ?????? ??? ???????
???????, ?????? ?????, ????????? ?????, ????
????????, ???????? ???? ?? ??????? ? ??????
?????????!
(?.?.)
33
Additional slides
34
(No Transcript)
35
(No Transcript)
36
Deviation of charged particle in extragalactic
magnetic fields
37
(No Transcript)
38
(No Transcript)
39
RS model with the small curvature is not similar
to a model with one large ED of the size
For instance,
can be realized only for
d is the number of EDs
solar distance
strongly limited by astrophysical bounds
40
Background RS metric
(Randall Sundrum, 1999)
Four-dimensional gravitational in the RS model
(Boos et al., 2002)
Expression is not covariant indices are raised
with the Minkowski tensor while the metric is
41
(No Transcript)
42
Neutrino telescope ANTARES
350 m
450 m
100 m
12 lines 3x25 PM
? 60 m
-2500 m
43
Radio signals from surface of the Moon
(detector GLUE)
44
Antarctic ice detector of GZK-neutrinos

• RICE - Radio ice Cherenkov
  experiment (South Pole)
• ANITA - Antarctic Impulsive Transient Antenna
  (Antarctica)
• IceCube (IceTop)
• AURA Askaryan Under ice Radio Array (South
  Pole)
• SPATS South Pole Acoustic Test System
• IceRay

45
(No Transcript)
46

• Hypothesis
• E-2 n spectrum
• nm? m only
• MC energy

Atm. n
Amanda 1y
Antares 1y
WB limit
Icecube
KM3NeT 1y
47
(No Transcript)
48
(No Transcript)
49
(No Transcript)
50
(No Transcript)