Research in the Intersection of the Higgs and Cosmology

The discovery of the Higgs boson is only the beginning when it comes to uncovering various mysteries about our universe. Currently, there is a lot of research on the possible link between the Higgs mechanism and cosmology. In this article, the topics of inflation, the false vacuum, dark matter, matter-antimatter asymmetry and what role the Higgs mechanism may play in all of them will be discussed.

Inflation

In cosmology, inflation is a theory that postulates that our universe had a period of accelerated expansion a fraction of a second after the Big Bang: the event that created the universe [1]. The majority of inflationary models require a scalar particle (i.e. a particle with no spin) dubbed the “inflaton” [2]. The Higgs boson is the only scalar boson (a particle with zero or integral spin) in the current Standard Model of particle physics, which classifies elementary particles. In turn, there have been some theories on the Higgs boson being the so-called “inflaton”. In their 2007 letter, Fedor Bezrukov and Mikhail Shaposhnikov claim that an interaction between the Higgs field and gravity may have led to cosmological inflation [2].

False Vacuum

A false or metastable vacuum is a vacuum that is not entirely stable. However, metastable vacuums are not actively decaying either [3]. If our universe is metastable, that means that an event called “vacuum decay” may take place due to a tiny “bubble” or part of the universe becoming a true, or stable, vacuum. This is highly unlikely, however, if it were to happen, then this would lead to the end of the universe. How though, does this all relate to the Higgs boson? Well, it appears that the stability of the universe may depend on the mass of the Higgs boson. In fact, the approximately 125 gigaelectronvolt mass of the Higgs boson may imply that the universe is actually metastable [4]. This is all speculation, however. To know for sure, more investigation into the Higgs boson and the Standard Model is necessary.

Higgs Boson and Dark Matter

The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) was famously used to detect the Higgs boson. Right now, it is also being used to probe for dark matter, [5] and the Higgs boson is vital to this search. ATLAS collaboration physicists are trying to find the decaying of the Higgs boson into other “invisible” particles, which would be able to be measured due to the creation of an energy imbalance in visible particles. Unfortunately, so far there has been no measurement of this decaying event.

Matter-Antimatter Asymmetry

Our universe should have equal amounts of matter and antimatter [6]. This is not the case with our observations. This issue of matter-antimatter asymmetry is one of the greatest research questions in the field of particle physics. As with the previous topics, the Higgs boson and Higgs field may be useful to this research. One article, published in 2015 and written by Alexander Kusenko, Lauren Pearce, and Louis Yang, states that if the (vacuum expectation) value of the Higgs field was high during the early universe and gradually decreased to its current value, that it may have caused a mass difference in matter and antimatter [7]. This may have led to matter “having the upperhand”. Furthermore, a 2019 theory extends the Standard Model by adding two additional Higgs doublets [8]. In this theory, the new Higgs fields (of the additional doublets) interact with the fermions in the Standard Model and create a violation of charge conjugation parity symmetry (CP-symmetry). In essence, CP-symmetry asserts that if a particle were to be interchanged with its antiparticle, the laws of physics would be constant while the particle’s coordinates in space will be reversed; there must be violation of this symmetry in order for this baryon asymmetry to exist.

Glossary

1. Higgs boson: A fundamental particle produced by a quantum excitation in the Higgs field.
2. Higgs field: A field of energy that is linked to the Higgs boson, which it uses to interact with other fundamental particles in order to “give” them their mass.
3. Higgs mechanism: The mechanism behind how the bosons carrying the weak nuclear force gain their mass.
4. Cosmology: The field of study that researches the origin, evolution, and fate of the universe.
5. Standard Model of particle physics: A theory that describes three out of the four fundamental forces in our universe (the one not included is gravity) as well as classifies all known elementary particles.
6. Large Hadron Collider: The world’s largest and highest-energy particle collider located at the European Organization for Nuclear Research, commonly known as CERN.
7. European Organization for Nuclear Research: A scientific research center that focuses on particle physics.
8. Dark matter: A type of matter that makes up 85% of matter in the universe believed to be a currently undetected particle.
9. Antimatter: Matter composed of antiparticles, which have the same properties as a given particle but opposite electromagnetic charge.
10. ATLAS: Stands for “A Toroidal LHC ApparatuS” and is a general purpose particle detector at Large Hadron Collider.

Bibliography

[1] Guth, Alan. 1981. \”Inflationary Universe: A Possible Solution To The Horizon And Flatness Problems\”. https://journals.aps.org/prd/abstract/10.1103/PhysRevD.23.347.

[2] Bezrukov, Fedor, and Mikhail Shaposhnikov. 2008. \”The Standard Model Higgs Boson As The Inflaton\”. Arxiv.Org. https://arxiv.org/abs/0710.3755v2.

[3] Mack, Katie. 2015. \”Vacuum Decay: The Ultimate Catastrophe\”. Cosmosmagazine.Com. https://cosmosmagazine.com/physics/vacuum-decay-ultimate-catastrophe.

[4] Kusenko, Alexander. 2015. \”Are We On The Brink Of The Higgs Abyss?\”. Physics.Aps.Org. https://physics.aps.org/articles/v8/108.

[5] \”ATLAS Probes Dark Matter Using The Higgs Boson\”. 2020. Home.Cern. https://home.cern/news/news/physics/atlas-probes-dark-matter-using-higgs-boson.

[6] \”The Matter-Antimatter Asymmetry Problem\”. 2020. Home.Cern. Accessed July 1. https://home.cern/science/physics/matter-antimatter-asymmetry-problem.

[7] Kusenko, Alexander, Lauren Pearce, and Louis Yang. 2015. \”Postinflationary Higgs Relaxation And The Origin Of Matter-Antimatter Asymmetry\”. Journals.Aps.Org. https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.114.061302.

[8] Davoudiasl, Hooman, Ian Lewis, and Matthew Sullivan. 2019. \”Higgs Troika For Baryon Asymmetry\”. Arxiv.Org. https://arxiv.org/abs/1909.02044.

Figure References

Figure 1: \”Inflation (Cosmology)\”. 2020. Wikiwand.Com. Accessed July 1. https://www.wikiwand.com/en/Inflation_(cosmology).

Figure 2: Mack, Katie. 2015. Twitter.Com. https://twitter.com/AstroKatie/status/574469118511857664.

About The Author

Hazal Kara is a rising junior at Hisar School in Istanbul, Turkey and a physics, math, and astrophysics editor at the Young Scientists Journal. She is passionate about science communication and literature. Her hobbies include game development, solving (or trying to solve) math problems, and creative writing. She hopes to become a physicist and writer in the future.