Stanford Pre Collegiate Summer presentation on the Large Hadron Collider (LHC)

The Large Hadron Collider

By Chongjia Wang, Akiyoshi Koide, Jack Mawhinney

Background Information 1.CERN 2.Standard Model 3.Hadron

CERN

Standard Model The Standard Model is the theory describing three of the four known fundamental forces, as well as classifying all known elementary particles.

Hadron

● A particle made from quarks and antiquarks ● Held together by the strong nuclear force ● Example: proton(the particle in LHC), neutron

Cool Facts

● 111 nations involved in designing, building and testing equipment and software ● The total cost of building the LHC was approximately £3.74 billion (4,675,878,900.00$ ) ● Runs for a circumference of 27 km (16.5 mi) ● Can recreate conditions that existed moments after the big bang ● May create a tiny black hole

The design: Particle acceleration ● First step is stripping hydrogen (protium) atoms of electrons ● chain of 4 accelerators (Linac 2, PSB, PS, SPS) ● Injects bunches into LHC in opposite directions

The design: Particle acceleration ● Radiofrequency cavities accelerate particles in tight bunches ● Magnetic fields keep particles in circular motion ● Ultrahigh vacuum inside the beam pipe, largest in the world

Luminosity ● Luminosity (m⁻²s⁻¹): ‫ ﱣ‬potential collisions per given cross section (σ) per second ● Integrated Luminosity: gives collisions occurring per cross section over a given period, measured in inverse femtobarns (1/Area)

Nevents/sec = Luminosity · Cross Section

The Design: Particle collision ● Collide at four locations around the accelerator ring, corresponding to the four particle detectors (ATLAS, CMS, ALICE, LHCb) ● Semiconductor detectors to measure trajectories of charged particles ● Calorimeters measure energies of particles ● Data then analysed and compared to current theories on particle physics

Applications of Relativity ● Particles moving very close to the speed of light γ ≈ 7460 β ≈ 0.999999991 ● Particles would observe large effects of time dilation and length contraction ● Small changes in velocity have large changes in energy

E = γmc²

Synchrotron Radiation â—? Radially accelerated charges produce electromagnetic radiation â—? Limits the amount of energy electrons can have in a circular accelerator

Main Result: Higgs Boson “THE GOD PARTICLE”

Fills in standard model, unifies electromagnetic and weak force

Higgs

Electroweak theory causes some particles to come out with 0 mass.

This is a problem for W/Z bosons

Problems Hierarchy Problem

Matter-Antimatter asymmetry

The Hierarchy Problem

To Explain Gravity vs Weak forces

Black Holes for Supersymmet ric Particles

Matter-Antimatter Asymmetry Problem

Answers?

What the LHCb has found (March 2019) For the first time! Asymmetry observed as CP violation in particle D0 Meson (Charm quarks)

CP symmetry = laws of physics apply same to particle and antiparticle Standard Model produces CP violation (Different behaviors)

Without dark matter, galaxies should tear themselves apart

To Recap: Hierarchy problem:

Matter Antimatter Asymmetry:

Supersymmetric particles

CP violation (particle antiparticle behavior) observed

Gravitons Black Hole decay to find elementary particles

Dark Matter could hopefully be observed in LHC collisions

^^^Hope to find with LHC

^^^Also hope with LHC

Bibliography “Large Hadron Collider.” Science and Technology Facilities Council, UK Research and Innovation, 18 Feb. 2019, stfc.ukri.org/research/particle-physics-and-particle-astrophysics/large-hadron-collider/.

Plettner, Thomas, et al. “The Impact of Einstein’s Theory of Special Relativity on Particle Accelerators.” Stanford, 2005, web.stanford.edu/~rlbyer/PDF_AllPubs/2005/407.pdf.

“Synchrotron Radiation.” Hyperphysics, hyperphysics.phy-astr.gsu.edu/hbase/Particles/synchrotron.html.

“LHC: How Fast Do These Protons Go?” Journal Batard, journal.batard.info/post/2008/09/12/lhc-how-fast-do-theseprotons-go.

Vidal, Xabier, and Ramon Manzano. “Cross Section.” Taking a Closer Look at the LHC, www.lhccloser.es/taking_a_closer_look_at_lhc/0.cross_section.

Bibliography Institute of Physics. “Particle Detection.” Institute of Physics, www.iop.org/resources/topic/archive/cern/index.html.

“Accelerators.” CERN, 2019, home.cern/science/accelerators.

Siegel, Ethan. “Five Years After The Higgs, What Else Has The LHC Found?” Forbes, Forbes Magazine, 11 Apr. 2018, www.forbes.com/sites/startswithabang/2018/04/11/five-years-after-the-higgs-what-else-has-the-lhcfound/#1e576fec552c.

Diamante, Litizia. “Key Plans for the next Two Years of the LHC.” CERN, 10 Dec. 2018, home.cern/news/news/accelerators/key-plans-next-two-years-lhc.

Adams, Todd. “10 Years of Large Hadron Collider Discoveries.” EarthSky, 16 Sept. 2018, earthsky.org/humanworld/large-hadron-collider-lhc-discoveries.