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Microscopic black hole detection in ultra high energy cosmic ray experiments M.C. Espirito Santo / LIP II Workshop on Black Holes, Lisboa, December 2009 ν

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PowerPoint PresentationMicroscopic black hole detection in ultra high energy cosmic ray experiments
M.C. Espirito Santo / LIP II Workshop on Black Holes, Lisboa, December 2009
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Outline
BH production in cosmic rays Why cosmic rays Why neutrinos Scenario
BH detection in cosmic rays Air shower detection 3 approaches – why & why not
Rates Showers characteristics Signatures
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
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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Complementary in specific aspects probing energies far beyond accelerator reach!
There are ultra high energy events !! √s > 400 TeV: a unique window
Much poorer detection capabilities Low fluxes Limited 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
p channel: SM cross-sections are huge!
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Scenario
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
BH instantaneous decay into all SM species According to nb of degrees of freedom Typical multiplicities tens to hundreds of particles
Main features of BH showers independent of formation and evolution details
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Combines 2 different techniques: Fluorescence telescopes Water Cherenkov stations
~ 10% of events are observed with both techniques: wealth of information about shower development.
Surface detectors
JEMJEM--EUSOEUSO OWLOWL
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
Approach I – Rates
Auger Collab., PRD 79 (2009)
For SM cross-sections: Auger chances mostly in earth-skimming
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Small EM component Large number of quarks & gluons
more nucleus-like q q’
J. Alvarez-Muniz
Small EM component Large number of quarks & gluons
more nucleus-like q q’
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
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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 CHARYBDIS Harrison,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 uncertain Present experiments are flux-limited Hard to discriminate between parameter values
Shower characteristics ? Detector limitations and shower fluctuations make it challenging Hybrid + 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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Microscopic black hole detectionin ultra high energy cosmic ray experiments
Outline
Approach I – Rates