Krish Ramkumar
4/15/2015
Why
does the Higgs field provide masses to only certain particles in the standard
model? For instance, why does the photon not have any mass? Is the Higgs field
constant throughout the universe?
These are the primary questions that I want
to address in the following blog. I must specify that since I have very limited
mathematical knowledge in the area of QFT, My final hypothesis is built purely
on conjecture.
Before I write about my hypothesis, I feel
the need to consolidate the present theories associated with the above
questions for the sake of continuity.
The standard model of particle physics has
established a strong framework to classify particles existing in the universe
and has narrowed down their respective functions.
There are two main families of particles namely,
fermions and the bosons. All elementary particles fall under the family of fermions
(Quarks that make up the protons and neutrons, leptons (electrons, neutrinos
etc)) and the bosons are carriers for the 4 fundamental forces (EM, G, Weak
nuclear, strong nuclear) we see in the universe. In order for these forces to
be transferred from point a to point b, some kind of mediator is required.
Bosons act as mediators. The electromagnetic force is carried across with the
help of photons, the weak nuclear force through W&Z bosons and the strong
nuclear forces with particles called gluons. We are not entirely sure about the
force carrier associated with the gravitational force at the moment. Although
physicists think that a mass-less and charge-less boson particle called ‘gravitons’
might be particles to carry the ripples (gravitational waves) in space-time.
This will make the standard model more complete.
Each
of these particles has some mass or no mass and the reason they inherit this
mass is due to the Higgs field mechanism. It has been established by great
minds and partial observations that right after the big bang, the universe started
to cool down and a field (Higgs field) was switched on giving rise elementary
particles with their set values. But what was the mechanism behind each of
these particles getting their respective masses? What went on when the Higgs
field was switched on? These questions were answered by looking into the
effects of the fundamental forces.
While the EM force and the gravitational
forces weaken gradually with distance from the source (Inverse sq law), the
nuclear force disappears suddenly within a short distance. Why does the nuclear
force behave differently from the other two fundamental forces?
The reason behind this conundrum is the Higgs
mechanism and the mass associated with the force carriers of the respective
forces.
At this point I would like to paraphrase a
great analogy put forth by physicist Sean Carroll. The following analogy makes
this profound problem more understandable.
Think of a lantern in the dark. As the
lantern moves away from you the light from the lantern weakens gradually
following the inverse square law thereby validating what happens in the case of
gravitation and EM. But if you think of the lantern as a source of nuclear
force, the lantern quickly disappears within a short distance. How does this
happen? It might happen if there is a shutter around the lantern that
completely shuts of the light from escaping (gluons that mediate the strong
nuclear force interact such that they create a shutter around the source) or if
the air around the lantern is filled with dense fog which shields the light
from propagating thorough the air. This fog is the Higgs field. The Higgs field
prevents the carrier of the weak force to propagate by providing resistance (inertia)
thus giving mass (a measure of resistance on an object in motion) to the force
carriers (W&Z Bosons).
But how does the Higgs field decide to
provide resistance to the W&Z bosons and not the photons (or gravitons) is
the question of interest as stated in the beginning?
The Higgs field seems to have no effect on
certain particles thus allowing them to move freely and are unperturbed under
the influence of the field. This goes to say that the field provides zero net
resistance to these particles thereby making them mass-less. Under the
assumption that the Higgs field is a constant field throughout the universe,
the particle, in my opinion must provide some kind of “counter resistance” or
anti resistance that enables it to balance the resistance offered by the field.
Working with this logic, massive particles should have “counter resistance”
that does not balance the resistance of the field.
Since we measure the quantity of a field by
its effects and not the field itself, we could measure the effects of the Higgs
field by measuring the effects of the mass-less particles moving through it.
The different masses of particles might be due to the amount of some kind of “exotic
anti- resistance” offered by the particle itself on the Higgs field and not the
Higgs field alone. Perhaps this will bring us closer to dark energy?
