David Doll

Particle Physics at CaltechA Grad Student Perspective

*In one slide

The particles represent our current theory of fundamental physicsMany outstanding questions:

“Gravity?”, “Neutrino Mass?”, “Matter vs. Anti Matter?”

My experiment dealt with answering the latter question

Introducing the Elephant – an Overview of Particle Physics*

Our theory does allow for a small amount (~1 Billion times too small) of asymmetry through the decay of heavy particles to light particles.

What can cause the imbalance?

e+ e-Y(4S)

bb

B0

B0

We reconstruct the B mesons (one is matter, the other anti-matter) to look for differences.

All measurements are consistent with our theoryAll except Matter/Anti matter asymmetry of courseThe theorists who gave us this theory won half of the Nobel

prize in physics last year.Where do we go from here?

Many new theories, “Beyond the Standard Model”-theories, try to come up with new sources of matter/anti matter differences

All must reproduce what has already been shownSearches with Babar’s data can already place limits on the

parameters of these new theories (my thesis deals with this)

What we do known’t

We look at a b quark turning into an s quark and emitting a photon.Very sensitive to the effects of New Physics (NP) modelsThe rate is around 1 in 10,000 B mesons decays in a mode

we care about

My Thesis – Quickly!!

An example “Feynman diagram”:

γ “Weak Force”-carriers (from first slide). Could be replaced by new particles in NP theories

Chance to go to Washington D.C. to lobby Congress on behalf of particle physicsOnly graduate student from my experiment (~500

collaborators)

Beyond my Thesis

~1/2 the group (it was 8AM!!)

Involved in the Caltech Grad Student CouncilThis year’s Advocacy Committee chairWorking to increase graduate student exposure to potential

donors as a way of increasing graduate student fellowshipsInvolvement in teaching/tutoring programs

RISE program – Only Math/Science focused tutor program in Pasadena Unified School District

YESS program – targets gifted under-represented minority students in physics and biology.

Life at Caltech

Getting to do ground breaking particle physics researchDid I mention my advisor (David Hitlin) was my

experiment’s first spokesman?With a great name comes great opportunitiesChance to participate in a variety of activities here at

Caltech

My Grad Experience Summary

Thank you!!