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

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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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