Microscopic black hole detectionin ultra high energy cosmic ray experiments
M.C. Espirito Santo / LIPII Workshop on Black Holes, Lisboa, December 2009
ν
Outline
BH production in cosmic raysWhy cosmic raysWhy neutrinosScenario
BH detection in cosmic raysAir shower detection3 approaches – why & why not
RatesShowers characteristics Signatures
ProspectsChallenges & uncertainties
ν + N BH hadrons
BH
ν
2
Why cosmic rays ?
Tiny BHs can be produced in particle collisions above the Planck scale M* ...
... In models with extra-dim we can have M* ~ TeV !
Addressing the hierarchy problem
BH gravity
EM
Stre
ngth
r
Gravity could be strong...
J.Feng
BH production at the LHC and in high energy cosmic rays!
Can cosmic ray detectors compete with the LHC? Not in the same energy range, but…
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Why cosmic rays ?
... In cosmic rays
Complementary in specific aspectsprobing energies far beyond accelerator reach!
There are ultra high energy events !! √s > 400 TeV: a unique window
Much poorer detection capabilitiesLow fluxesLimited kinematic region
LHC 4
Why neutrinos ?
Cosmic neutrinos with energies above 106 GeV could be favourable beam.
cross-sections may be significantly enhanced w.r.t. SM
No observations above E ~ 10 6 GeV, but predicted on rather solid grounds
Cosmogenic neutrinos
P γCMB → n π+ → μ+ ν μ
ν channel: Low background from standard cosmic rays Inclined showers starting deep in the atmosphere
ν Ν
SM
n = 1,…,7
Feng & Shapere, PRL 88 (2001)
p channel: SM cross-sections are huge!
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Scenario
ν + N BH hadrons
Parameters: M*, MBH, n
Interaction length (109 TeV) ~ 1.1x107 g/cm2
Horizontal atmosphere length ~ 3.6x104 g/cm2
Instantaneous BH production and evaporation, originating quasi-horizontal showers deep in the atmosphere ν
Geometrical cross-section
Be aware of: form factor F and inelasticity (MBH<√s)
Be aware of: PDF uncertainties, impact parameter, and the minimum BH mass for which the semiclassical cross section is valid (~ few M*)
νp cross-section
BHinstantaneous decay into all SM species According to nb of degrees of freedom Typical multiplicities tens to hundreds of particles
Main features of BH showersindependent of formation and evolution details
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Air shower detection - Auger
E. Zas
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Air shower detection - Auger
E. Zas
Fluorescence light
Combines 2 different techniques: Fluorescence telescopesWater Cherenkov stations
~ 10% of events are observed with both techniques: wealth of information about shower development.
Surface detectors
3000 km2 Hybrid detector
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Fluorescence detector:
Surface detector:
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Air shower detection - Auger
Air shower detection: from Space
JEMJEM--EUSOEUSO OWLOWL
~ 300.000 km2 > 106 km2
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Approach I – Rates
Large rates w.r.t. to SM are key issue
But there large uncertainties in several of the “ingredients”
Hard to constrain the Model parameters
Ahn, Ave, Cavaglia & Olinto, PRD 68 (2003)Anchordoqui et al Phys. Lett. B 594 (2004) 10
Fluxes are uncertain... Many models!
WB
Any ν observation would great news!!
Approach I – Rates
Cosmogenic ν flux in the limit of present experiments
Auger Collab., PRD 79 (2009)
For SM cross-sections: Auger chances mostly in earth-skimming
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Approach II – Shower characteristics
BH vs. SM ν CC: showers are clearly different!
Small EM componentLarge number of quarks & gluons
more nucleus-like q q’
W
ν l EM shower
BH
Ahn & Cavaglia, PRD 73 (2006)
J. Alvarez-Muniz
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Approach II – Shower characteristics
BH vs. SM ν CC: showers are clearly different!
Small EM componentLarge number of quarks & gluons
more nucleus-like q q’
W
ν l EM shower
BH
Ahn & Cavaglia, PRD 73 (2006)
J. Alvarez-Muniz
But detection capabilities are limited...And there are shower to shower fluctuations!
Ahn, Ave, Cavaglia & Olinto, PRD 68 (2003)ΔXm = Xmax-Xo 12
Approach II – Shower characteristics
Needs a lot of statistics for differences to overcome fluctuations
hybrid events are most promising
ϒ = Xmax-X0.1
Ahn, Ave, Cavaglia & Olinto, PRD 68 (2003)
Ahn, Ave, Cavaglia & Olinto, PRD 68 (2003)
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Approach III – distinctive signatures
τ
νBH
2nd bang – decay of an energetic tau
1st bang – BH production & evaporation A narrow window...
Detectability of the second bang depends on the tau energy, which determines both the tau decay length and the energy of the second shower.
A BH double bang viewed by EUSO
V. Cardoso et al, Astrop. Phys. 22 (2005)
An order of magnitude computation with simple model
Chances of seeing the 2nd bang once the 1st is detected
A few % of the events give double bangs in EUSO
Observation window constrained by field of view and energy threshold 14
Approach III – distinctive signatures
Taus from BH decays and W/Z/t decay treated using PYTHIA ( Lint >> Ldec)
V. Cardoso et al, Astrop. Phys. 22 (2005)
Mini-BH production and decay simulated with CHARYBDISHarrison,Richardson, Webber, hep-ph/0307305
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Prospects
High energy cosmic rays may be the right scenario for mini BH searches
The energy window is unique !!But there are many challenges and uncertainties …
Measuring event rates ? cross-sections and fluxes are uncertainPresent experiments are flux-limitedHard to discriminate between parameter values
Shower characteristics ?Detector limitations and shower fluctuations make it challengingHybrid + high statistics promising!
Striking signatures?Double bangs in future (huge) detectors?
ν
When the first ν shower is seen, it might be hard to tell if it is a BH,
but it will be a great observation!!
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