HIGGS BOSON: HIGGS BOSON The God Particle PRELUDE TO THE HIGGS – BOSON The Standard Model of Particle Physics: PRELUDE TO THE HIGGS – BOSON The Standard Model of Particle Physics The Standard Model is a theory on which particle physics is based. It is a theory concerning the above interactions which mediate the dynamics of known sub-atomic particles. It consists of 16 blocks plus the Higgs-Boson, making a total of 17. It gives reason to why the electromagnetic force (force between charged particles) , weak nuclear force (radioactive-decay, neutrino emission) and the strong nuclear force interact as such. One disadvantage is that it does not account for the 4 th fundamental force – Gravity. It is also regarded as a theory of almost everything. What is a boson? : What is a boson? As we know, there are four fundamental forces of nature – Strong Nuclear Force, Weak Nuclear Force, Gravitational Force and Electromagnetic Force. These forces have “force-carriers” which are particles that interact using this force. Bosons are often force-carrier particles, and in the Standard Model, these are gauge bosons. The 4 Gauge Bosons: The 4 Gauge Bosons FUNDAMENTAL FORCE OF NATURE GAUGE BOSON Electromagnetic Force Photon Gravity Graviton (hypothetical, not in Standard Model) Strong Nuclear Force Gluons Weak Nuclear Force W and Z bosons What is the Higgs-Boson? : What is the Higgs-Boson? The Higgs-boson is believed to be the carrier of mass and proves the existence of the Higgs Field. But, you might ask – Can’t particles have mass without the Higgs Boson? The answer is simple. All particles in the universe are initially assumed to have no mass. The Higgs Field covers the entire universe and bogs down particles with mass. It may allow certain particles like photons to move through undisturbed which is why they do not have mass, whereas it may affect bosons like Z and W bosons which are massive and are bogged down with mass. The Higgs Boson thus acts as a force-carrier and transmits mass to other particles. Properties of the Higgs-Boson: Properties of the Higgs-Boson In the Standard Model, the Higgs-Boson is a boson with no spin, electric charge, or color charge. It is also very unstable, decaying into other particles almost immediately. It is one of the four components of the Higgs field, constituting a scalar field, with two neutral and two electrically charged components. The field has nonzero strength everywhere (including otherwise empty space) which in its vacuum state breaks the weak symmetry of the electroweak interaction. When this happens, three components of the Higgs field become the longitudinal components of the W and Z bosons of the weak force. The remaining electrically neutral component separately couples to other particles known as fermions (quarks and leptons) causing these to acquire mass as well. The Discovery: The Discovery What happened?: What happened? On 4 July 2012, an unknown particle having a mass between 125 – 127 Gev /c 2 (2.228 x 10 -26 to 2.26x 10 -26 kg) was observed separately in two proton-proton collision events in the Large Hadron Collider particle accelerator. Compact Muon Solenoid (CMS) and A Toroidal LHS Apparatus (ATLAS) – two particle detectors – detected the presence of this boson. It was tentatively confirmed to exist in March 2013 due to its consistency with the theory proposed by Kibble, Guralnik , Hagen, Englert , Brout , and Peter Higgs in their 1964 papers which got them the 2010 J.J. Sakurai Prize. Importance of its Discovery: Importance of its Discovery The Higgs Boson is the last piece of the Standard Model of Particle Physics. It gives further credence to the stability of the model, and also gives a solution to the problem of Gauge Invariance, i.e it explains why some particles have mass when they are not supposed to symmetrically. Gauge bosons are not supposed to have any mass being force-carriers and must follow the symmetry. But, the W and Z bosons, which are the gauge bosons for the weak force have mass, which breaks the symmetry that photons and gluons – the other gauge bosons – follow. This has largely been attributed to the existence of the Higgs Field and the Higgs Mechanism. Higgs mechanism is a process by which these gauge bosons can get mass without completely breaking the symmetry, a process known as spontaneous symmetry breaking. Here, the gauge boson respects the symmetry but the system as a whole, thanks to the Higgs Field, breaks the symmetry, thus not explicitly breaking it. The Higgs Boson owing to the theory of the Higgs Field and Higgs mechanism also answers the question – Why does the weak force have a much shorter range than the gravitational force? The weak force is much stronger but has very limited range whereas the gravitational force has unlimited range. The limited range is due to the mass gained by the Z and W bosons because of the Higgs Mechanism, whereas the bosons for gravity (if they exist) may not be affected by said mechanism, i.e the Higgs Field may allow certain particles to pass freely, whereas others are given mass. Future of the Higgs-Boson and possible impact: Future of the Higgs-Boson and possible impact While it was tentatively confirmed by the scientific community, there is still a lot of doubt so as to whether the boson is consistent with all the properties as described in the 1964 Papers. The discovery also gives an insight into cosmic inflation, nature and fate of the universe, energy of vacuum, and a link to the cosmological constant problem. The Higgs mechanism also predicts the ratio between the W and Z boson masses as well as their couplings with each other and with the Standard Model quarks and leptons. There are no known immediate technological benefits to man, but as with many scientific discoveries, their practical uses may take years to emerge, as in the case of radio waves which were initially thought useless and just a byproduct but now, we wouldn’t have satellite navigation, GPS, radar, medicine, television, wireless computing and so on. But there is one thing we can all be certain of, and that is – It’s existence and knowledge of properties will impact a whole range of scientific fields and answer many unanswered questions in physics. It would give us intricate knowledge of the interactions between sub-atomic or elementary particles, and hopefully a solution to how everything works. : HOPE YOU ENJOYED THE PRESENTATION ! THANK YOU !