HIGHER DIMENSIONAL BLACK HOLES AT LHC Halil Gamsizkan gamsizmetu'edu'tr

1
HIGHER DIMENSIONAL BLACK HOLES AT LHCHalil
Gamsizkangamsiz_at_metu.edu.tr
2
I will discuss

• Classical black holes
• ADD model of large extra dimensions
• Higher dimensional black holes
• Experimentation
• Current results

3
Classical Black Holes

• A black hole is a region of space that has so
  much mass concentrated in it that there is no way
  for a nearby object to escape its gravitational
  pull.
• The Schwarzschild radius is the radius (from the
  center of the Black-Hole's mass) at which the
  escape velocity equals the speed of light.

1/17
4
Hawking Radiation

• BHs can decay via a quantum mechanical process
• Space-time near a BH undergoes energy
  fluctuations where amount of energy created is
  determined by the uncertainty relation ?
• If for a certain time interval, created energy is
  high enough, virtual particle-antiparticle pairs
  are formed.
• Because of strong gravitation near a BH, one of
  the particles falls into the BH, while other
  virtual particle may fly away to infinity.
• Flying away particle carries the energy (mass)
  taken from the BHs gravitational field. Hence
  the BH slowly evaporates
• BH seems like a blackbody emitting radiation
  corresponding to a Hawking temperature of

A BH with Hawking temperature higher than cosmic
microwave background is visible. This
corresponds to a mass of 10-26 grams and an rs of
10-40 m.
2/17
5
Hierarchy Problem
THE FOUR FORCES

• Expectation is that all four forces are different
  reflections of a single force Unification.
• Electroweak unification occurs at MewTeV.
• On the other hand, grand unification occurs at
  MPlanck1018 GeV.
• Why is there such a large hierarchy?

3/17
6
Large Extra Dimensions ADD Model

• What if the Planck scale were TeV?
• The IDEA
• Let the gravitational coupling get stronger at
  short distances
• (r lt 1 cm).
• A mechanism to increase the gravitational
  coupling is the existence of n compactified large
  extra dimensions which open up below a certain
  distance R.
• Radii of LED R is far larger than the Planck
  distance (the reason why they are called large
  ED) so gravity already gets stronger before
  reaching the Planck distance 1/MPl and
  unification can happen at an energy scale far
  lower than Mpl.

4/17
7
ADD Model

• Some part of gravity (which we cannot perceive)
  might be wondering in these extra dimensions, so
  gravitational coupling may increase with the
  contributions coming from the components of
  gravity in the extra dimensions (at distances
  rltR). At distances rgtR, gravity is weak since
  there are no contribution from extra dimensions.
• At distances MPlltrltR, All forces other than
  gravity are localized to the 4-dimensional
  manifold (called the 3-brane). but gravity is
  free to propagate in LED.
• SM fields cant penetrate the n LED below M(4n).
  They live in a 3-brane, above M(4n) all fields
  can wonder in the LED.

Extra Dimension
5/17
8
ADD Model

• THERE IS ONLY ONE UNIFICATION SCALE in 4n
  dimensions which is the current EW scale MEW
  TeV
• Newtons law changes as (for rltR)
• F 1/R2 ?1/Rn2
• Effective Planck scale
• Msn2MPl2/Rn
• For n 1, R 1011 m ... impossible!
• For n 2, R 0.1 1 mm ... might be possible!

6/17
9
Higher Dimensional Black Holes

• A black hole can be formed no matter what the
  amount of matter is, just compress it into the
  Schwarzschild radius.
• Smallest energy needed to make a classical BH
  can be found by comparing the impact parameter
  (b1/E1/MBH) and Schwarzschild radius
  (rsMBH/MPL2). We find MBHgtMPL!!
• Schwarzschild radius for a 4n black hole (from
  4n-dimensional Einstein equations)
• Comparing rs(4) and rs(4n), we get
• rs(4) lt
  rs(4n) lt R
• A 4n BH is BIGGER than a 4-dimensional BH with
  the same mass.

7/17
10
Higher Dimensional Black Holes

• At impact parameters smaller than the
  4n-dimensional Schwarzschild radius and at COM
  energies greater than M(4n), proton-proton
  collusion cross-section is dominated totally by
  inelastic BH production.
• For M(4n)2 TeV and n3, ?430 pb, this
  corresponds to 4.3x106 black holes per year at
  low luminosity LHC operation (1 BH event every
  10 seconds).

8/17
11
Experimentation

• LHC will be operating at 2007
• Four experiments are under construction, among
  which
• are CMS and ATLAS.
• These are general purpose detectors, which may
  host
• black hole events.
• Our group is in collaboration
• with the CMS experiment.

CMS Detector weighs 14500 Tons!!!
9/17
12
Black Hole Production

• For a fixed black hole mass, the x-sect is lower
  for a higher number of extra dimensions.
• For a fixed number of extra dimensions, the
  x-sect is lower for increasing BH mass

10/17
13
Simulation

• CMS OO simulation software is used.
• (Almost) Fully written in C, runs in Linux.
• Insanely complicated (gtmillions lines of code,
  GBs to install), permanently under construction
• Complexity of the software reflects the
  complexity of the detector/experiment.
• Phases of simulation
• Charybdis CMKIN Event generation
• OSCAR Simulation
• ORCA Digitization
• ORCA Reconstruction
• ORCA Analysis

1000 event 4GB, 12days
11/17
14
Black Hole Decay Signatures

• Total BH cross section is large. BH formation
  totally dominates.
• High multiplicity of final state particles (gt4)
• End products have a spherical distribution caused
  by the thermal nature of radiation.
• Observed transverse energies are high because of
  high sphericity. Almost ½ of BH mass radiates
  off to transverse direction.
• Possibility of seing final state products with
  energies M(4n).
• Ratios of emitted particle species are those
  belonging to Hawking radiation decay is
  democratic, e.g. jets / leptons ratio is 7.5
  1
• Decay takes 10-27 seconds!

12/17
15
What to Analyze

• BH invariant mass reconstruction,
• BH Hawking temperature, number of extra
  dimensions.
• Beyond these, we focused on Higgs coming out of
  the BH decay.

13/17
16
Current Results
A preliminary analysis is already made (big
production is not ready yet). 50K BH Monte Carlo
events (TRUENOIR Monte Carlo, Greg Landsberg, et.
al.) Interfaced with CMSJET, which is a fast
detector simulation for CMS (Compact Muon
Solenoid detector) at LHC. Following Higgs
decay channels are already examined pp -gt BH
-gt H -gt jj pp -gt BH -gt H -gt WW gt l?l? pp -gt BH
-gt H -gt WW -gt l?jj and compared with the
corresponding Standard Model Higgs decay
channels. BH mass reconstructions were made.
Hawking radiation properties (Hawking
temperature, decay products) were examined.
14/17
17
Black Hole Invariant Mass Reconstruction
15/17
18
Current Results
Number of Entries 3169 Peak 1 68.47 29.22 GeV
(W/Z) Peak 2 124.91 12.93 GeV (H) Peak 3
196.91 75.71 GeV (t) ChiSquare 1.373
H 124.91GeV
W/Z 68.47GeV
t 196.91GeV
pp -gt BH -gt H -gt jj
16/17
19
Conclusions

• BLACK HOLE CREATION COULD LEAD TO THREE IMPORTANT
  PHYSICAL RESULTS
• Estimation of spacetime dimensionality and
  geometry.
• Proof of Hawking radiation.
• Discovery of the Higgs boson.

17/17
20
References

• S. Dimopoulos, G. Landsberg, Phys. Rev. Lett. 87,
  161602 (2001) hep-ph/0106295
• S. Sekmen and M. T. Zeyrek, Eur. Phys. J. C 39,
  503-509 (2005)
• C.M. Harris et. al, hep-ph/0411022
• S. Sekmen, M.Sc. Thesis, METU, Ankara, 2003
• BH simulation photo Robert Nemiroff (MTU)

Waiting for real data