269B class organizational meeting

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269B class organizational meeting
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LHC and Geneva
Main CERN Campus ATLAS
CMS
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Today (good timing ?)

• 7 TeV collisions, but miniscule luminosity (50 Hz
  of proton-proton collisions)

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Tomorrow
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Classes of Topics

• Fundamental physics
• E.g. Higgs, Supersymmetry, large extra dimensions
• Phenomenology the interplay between theory
  and experiment
• E.g. partons in protons, hard scattering,
  ordinary particles, jets
• General experimental issues
• E.g. accelerators, measuring momentum and energy
• Specific experimental issues
• E.g. pixel detectors, CMS versus ATLAS
• The future of physics at the energy frontier
• E.g. muon colliders, plasma wakefield acceleration

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More detailed list of topics

• Fundamental physics
• Higgs
• Supersymmetry (several types)
• Z and W particles
• Techniparticles
• Large extra dimensions, Kaluza-Klein particles,
  black holes
• Compositeness
• Magnetic monopoles
• b and t quarks
• Massive charged stable particles
• Phenomenology the interplay between theory
  and experiment
• Partons in protons
• Elastic and diffractive scattering
• Hard scattering
• ordinary particles
• Heavy quarks (b and t)
• jets

• General experimental issues
• Accelerators
• Luminosity
• Measuring momentum(tracking)
• Measuring energy (sampling calorimeters)
• -Muon systems
• Particle flow
• Specific experimental issues
• Pixel, Si strip tracking detectors
• CMS versus ATLAS
• Data analysis techniques
• Examine past discoveries, measurements
• The future of physics at the energy frontier
• Upgrades to LHC
• ILC and CLIC electron positron colliders
• muon colliders
• plasma wakefield acceleration

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Organizational issues

• What is expected?
• Kind of apprenticeship experience, tailored to
  individual
• Grading scheme (attendance, participation, talk
  or paper)
• Who is enrolled?
• When to meet?

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A Superficial Introduction
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Known Particle Physics

• Assume relativistic quantum mechanics (field
  theory)
• The Standard Model (1974) has two basic
  principles
• Symmetry at every point in space-time
• Symmetry breaking
• Only the 1st principle is beautiful

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Symmetry

• aka SU3xSU2xU1 a rotation symmetry at every
  point in space-time
• Explains the Strong (SU3) and weak (SU2) nuclear
  forces
• Explains Electromagnetism (U1)

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Symmetry breaking

• Simple classical example vertical pencil
• Introducing the Higgs mechanism
• A special particle that has a strange potential
  energy function in the vacuum

Massive electrons, quarks, neutrinos, W and Z,
and other particles
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Standard Model (too much) Success!

• 1974 Standard Model emerged with the November
  revolution
• 1979 I became a grad student
• For 34 years no discrepancy has been found ??
• All of the known fundamental particles are listed
  below.
• The Higgs is the fundamental particle that allows
  Electroweak unification. The only missing piece.
  The only scalar (Spin 0) particle.

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Tevatron vs. LHC Higgs
LEP-TeV working group fit mHlt 157 GeV (95 CL)

• Low-mass (lt130 GeV)
• Favored by precision data fits
• Experimentally very difficult

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Heres what a Higgs particle might look like (H
?ZZ?4?)

• A simulation
• Muons in green.
• The golden discovery mode for H mass gt135 GeV

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Technicolor

• Theories beyond the Standard Model (sometimes,
  but not always, GUTs) which do not have a scalar
  Higgs field.
• Details (see Wikipedia)
• Instead, they have a larger number of fermion
  fields than the Standard Model and involve a
  larger gauge group.
• This larger gauge group is spontaneously broken
  down to the Standard Model group as fermion
  condensates form.

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GUTs and the Higgs particle

• GUTsGrand Unified Theories
• Einstein tried but failed
• The SU3xSU2xU1 symmetries come from one big
  symmetry
• A beautiful idea
• Forces of nature merge into one force eventually
  (at high energy)

?
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GUTs seem incompatible with Higgs

• Fine corrections to the Higgs mass tend to
  become huge (1015 GeV/c2 or more), this cannot
  be
• Known as the hierarchy problem

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Supersymmetry (SUSY)

• SM particles have supersymmetric partners
• Differ by 1/2 unit in spin
• Sfermions (squarks, selectron, smuon, ...) spin
  0
• Gauginos (chargino, neutralino, gluino,) spin
  1/2

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Supersymmetry

• A symmetry that relates spins (fermions to
  bosons)
• One new superpartner for every known elementary
  particle.
• The superpartner differs only by half a unit of
  spin, and its mass.
• The lightest supersymmetric particle is the best
  candidate for Dark Matter
• If supersymmetry exists close to the TeV energy
  scale, it
• Solves the hierarchy problem
• The early universe should have produced just
  about the right amount of Dark Matter
• Supersymmetry is also a consequence of most
  versions of string theory
• though it can exist in nature even if string
  theory is wrong.

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SupersymmetryParticles Galore
Mass GeV
Example a whole new spectrum waiting at a few
hundred GeV mass?
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SUSY also fixes GUTs details

• Standard Model only

• A simple SUSY model

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Large extra dimensions, R-S

• Large extra dimensions (1998)
• To explain the weakness of gravity relative to
  the other forces.
• Fields of the Standard Model are confined to a
  four-dimensional membrane, while gravity
  propagates in several additional spatial
  dimensions that are large compared to the Planck
  scale
• Production of black holes at the LHC??
• Randall-Sundrum models (1999)
• our Universe is a five-dimensional anti de Sitter
  space and the elementary particles except for the
  graviton are localized on a (31)-dimensional
  brane or branes

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Modern Particle Accelerators
The particles are guided around a ring by strong
magnets so they can gain energy over many cycles
and then remain stored for hours or days
The particles gain energy by surfing on the
electric fields of well-timed radio oscillations
(in a cavity like a microwave oven)
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CERN Accelerator Complex

• LHC is designed for 14 TeV energy (7 TeV per
  proton in each beam)

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Add gt1500 dipole and quadrupole magnets, liquid
helium services
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..and Two Large Detectors
ATLAS
CMS

• Beams collide 40 million times producing 1
  billion proton-proton collisions every second
• Typical data run will last 9 months

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Context

• See http//www.nature.com/nature/journal/v448/n715
  1/full/nature06076.html
• 1987 (Reagan) the U.S. proposed to build a 40 TeV
  collider (the SSC) in Texas.
• 1991 CERN proposed to re-use an existing
  accelerator tunnel to build a wimpy 14 TeV
  collider.
• UCLA Prof. Dave Cline was one of a handful of
  (unfunded) U.S. physicists involved in LHC.
• 1993 the SSC was killed by Congress (Clinton)
• 1994 UCLA and other U.S. institutions joined the
  LHC effort
• Then gt14 years of planning, prototyping, and
  construction
• Dec. 2009 collisions at 0.9 2.36 TeV
• Mar. 2010 collisions at 7 TeV (Fermilab 1.96 TeV)