W-boson

In news– Recently, researchers from Collider Detector at Fermilab (CDF) Collaboration in the U.S., announced that they have made a precise measurement of the mass of the W boson.

Key updates-

According to the researchers, this precisely determined value did not match with the estimates from the standard model of particle physics.
The recent experiment which measured the mass of the W boson as 80,433.5 +/- 9.4 Mev/c2 is more than what is expected from the standard model (80,357 +/- 8 MeV/c2).
This result is highly significant because this implies the incompleteness of the standard model description.
This is a major claim, since the standard model has been extraordinarily successful in the past decades.
However, this is not the last word, as the mass discrepancy of the W boson needs to be checked and confirmed to the same accuracy by other facilities, for example, the Large Hadron Collider (LHC).

What is W-boson?

The W boson is an elementary particle that plays an important role in mediating weak nuclear interactions.
The weak nuclear force is one of the four fundamental interactions between matter particles in physics, the others being electromagnetic interaction, strong nuclear interaction and gravitational interactions.
In particle physics, the W and Z bosons are vector bosons that are together known as the weak bosons or more generally as the intermediate vector bosons.
In weak interactions there are three such ‘gauge bosons’ – the W+ (W-plus), W- (W-minus) and Z particles.

The W boson was first seen in 1983 at CERN, located on the Franco-Swiss border.

Unlike the photon, which is massless, the W bosons are quite massive, which results in the force they mediate, the weak force being very short ranged.
Unlike the photon, the W-plus and W-minus are charged and by exchanging such bosons, a neutron can change into a proton, for example. This helps in the transmutation of elements.
The W boson helps the interactions that make the Sun burn and produce energy.

The standard model of elementary particle physics-

It is a theoretical construct in physics that describes particles of matter and their interaction.
It is a description that views the elementary particles of the world as being connected by mathematical symmetries, just as an object and its mirror image are connected by a bilateral (left–right) symmetry.
These are mathematical groups generated by continuous transformations from, say, one particle to another.
According to this model there are a finite number of fundamental particles which are represented by the characteristic “eigen” states of these groups.
The particles predicted by the model, such as the Z boson, have been seen in experiments and the last to be discovered, in 2012, was the Higgs boson which gives mass to the heavy particles.
The standard model is thought to be incomplete because it gives a unified picture of only three of the four fundamental forces of nature — electromagnetic, weak nuclear, strong nuclear and gravitational interactions — it totally omits gravity.
So, in the grand plan of unifying all forces so that a single equation would describe all the interactions of matter, the standard model was found to be lacking.
The other gap in the standard model is that it does not include a description of dark matter particles. So far these have been detected only through their gravitational pull on surrounding matter.
The symmetries of the standard model are known as gauge symmetries, as they are generated by “gauge transformations” which are a set of continuous transformations (like rotation is a continuous transformation). Each symmetry is associated with a gauge boson.
For example, the gauge boson associated with electromagnetic interactions is the photon.
The gauge bosons associated with weak interactions are the W and Z bosons.

About CERN-

The European Organization for Nuclear Research known as CERN( derived from the name Conseil européen pour la recherche nucléaire), is a European research organization that operates the largest particle physics laboratory in the world.
Established in 1954, the organization is based in a northwest suburb of Geneva on the Franco–Swiss border and has 23 member states.
Israel is the only non-European country granted full membership.
CERN is an official United Nations Observer.
CERN’s main function is to provide the particle accelerators and other infrastructure needed for high-energy physics research – as a result, numerous experiments have been constructed at CERN through international collaborations.
CERN is the site of the Large Hadron Collider (LHC), the world’s largest and highest-energy particle collider.
12 founding Member States of CERN: Belgium, Denmark, France, the Federal Republic of Germany, Greece, Italy, the Netherlands, Norway, Sweden, Switzerland, the United Kingdom, and Yugoslavia.