Tag Archives: standard model

This is Not Your Father’s Universe!

When I was learning astronomy in the 60s and 70s, we were still debating whether Big Bang or Stady State were the most accurate models for our universe. We also wondered about how galaxies like our Milky Way formed, and whether black holes existed. The idea that planets beyond our solar system existed was pure science fiction and no astronomers spent any time trying to predict what they might look like. As someone who has reached the ripe old age of 70, I am amazed how much progress we have made, from the discovery of supermassive black holes and exoplanets, to dark matter and gravitational radiation. The pace of discovery continues to increase, and our theoretical ideas are now getting confirmed or thrown out at record pace. There are still some issues that remain deliciously mysterious. Here are my favorite Seven Mysteries of the Universe!

1-How to Build a Galaxy: In astronomy, we used to think that it would take the universe a long time to build galaxies like our Milky Way, Thanks to the new discoveries by the Webb Space Telescope, we now have a ring-side seat to how this happens, and boy is it a fast process!

The oldest galaxies discovered with the Hubble Space Telescope date back to between 400 and 500 million years after the Big Bang. A few weeks ago, Webb spotted a galaxy that seems to have formed only 300 million years after the Big Bang. Rather than the massive galaxies like the Milky Way, these young galaxies resemble the dwarf galaxies like the Large Magellanic Cloud, perhaps only 1/10 the mass of our galaxy and filled with enormus numbers of massive, luminous stars. The above image from Hubble is a nearby galaxy called M-33 that has a mass of about 50 billion suns. There were lots of these smaller galaxies being formed during the first 300 million years after the Big Bang.

It looks like the universe emerged from the Dark Ages and immediately started building galaxies. In time, these fragments collided and merged to become the more massive galaxies we see around us, so we are only just starting to see how galaxy-building happens. Our Milky Way was formed some 1 billion years after the Big Bang, so the galaxy fragments being spotted by Webb have another 700 million years to go to make bigger things. Back in 2012, Hubble had already discovered the earliest spiral galaxy seen by then; a galaxy called Q2343-BX442, camping out at 3 billion years after the Big Bang. In 2021, an even younger spiral galaxy was spotted, called BRI 1335-0417, seen as it was about 1.4 billon years after the Big Bang.

So we are now watching how galaxies are being formed almost right before our eyes! Previous ideas that I learned about as an undergraduate, in which galaxies are formed ‘top-down’ from large collections of matter that fragment into stars, now seem wrong or incomplete. The better idea is that smaller collections of matter form stars and then merge together to build larger systems – called the ‘bottom-up’ model. This process is very, very fast! Among the smallest of these ‘galaxies’ are things destined to become the globular clusters we see today.

2-Supermassive Black Holes: The most distant and youngest supermassive black hole was discovered in 2021. Called J0313-1806, its light left it to reach us when the universe was only 670 million years old. Its mass, however, is a gargantuan 1.6 BILLION times the mass of our sun. Even if the formation of this black hole started at the end of the Dark Ages ca 100 million years after the Big Bang, it would have to absorb matter at the rate of three suns every year on average. That explains its quasar energy, but still…it is unimaginable how these things can grow so fast! The only working idea is that they started from seed masses about 10,000 the mass of our sun and grew from there. But how were the seed masses formed? This remains a mystery today.

3-The Theory of everything: The next Big Thing that I have been following since the 1960s is the search for what some call the Theory of Everything. Exciting theoretical advancements were made in the 1940s and 1960s to create accurate mathematical models for the three nongravity forces, called the electromagnetic, weak and strong forces. Physicists call this the Standard Model, and every physicist learns its details as students in graduate school. By the early 1980s, string theory was able to add gravity to the mix and go beyond the Standard Model. It appeared that the pursuit of a unified theory had reached its apex. Fifty years later, this expectation has all but collapsed.

Experiments at the Large Hadron Collider continue to show how the universe does not like something called supersymmetry in our low-energy universe. Supersymmetry is a key ingredient to string theory because it lets you change one kind of particle (field) into another, which is a key ingredient to any unified theory. So the simplest versions of string theory rise or fall based on whether supersymmetry exists or not. For over a decade, physicists have tried to find places in the so-called Standard Model where supersymmetry should make its appearance, but it has been a complete no-show. Its not just that this failure is a problem for creating a more elegant theory of how forces works, but it also affects astronomy as well.

https://penntoday.upenn.edu/news/making-sense-string-theory

Personally, when string theory hit the stage in the 1980’s I, like many other astronomers and physicists, thought that we were on the verge of solving this challenge of unifying gravity with the other forces, but this has not been the reality. Even today, I see no promissing solutions to this vexing problem since apparently the data shows that simple string theory is apparently on a wrong theoretical track.

One cheerful note: For neutrinos, the path from theoretical prediction to experimental observation took 25 years. For the Higgs boson, it took 50 years. And for gravitational waves, it took a full 100 years. We may just have to be patient…for another 100 years!

4-Dark Matter: The biggest missing ingredient to the cosmos today is called dark matter. When astronomers ‘weigh’ the universe, they discover that 4.6% of its gravitating ‘stuff’ is in ordinary matter (atoms,. stars, gas, neutron stars etc), but a whopping 24% is in some other ‘stuff’ that only appears by its gravity. It is otherwise completely invisible. Putting this another way, it’s as though four out of every five stars that make up our Milky Way were completely invisible.

Dark matter in Abell 1679.

Because we deeply believe that dark matter must be tracable to a new kind of particle, and because the Standard Model gives us an accounting of all the kinds of elementary particles from which our universe is built, the dark matter particle has to be a part of the Standard Model…but it isn’t!!!! Only by extending the Standard Model to a bigger theory (like string theory) can we logically and mathematically add new kinds of particles to a New Standard Model- one of which would be the dark matter particle. String theory even gives us a perfect candidate called the neutralino! But the LHC experiments have told us for over a decade that there is nothing wrong with the Standard Model and no missing particles. Astronomers say that dark matter is real, but physicists can’t find it….anywhere. Well…maybe not ALL astronomers think it’s real. So the debate continues.

Personally, I had heard about ‘missing mass’ in the 1960s but we were all convinced we would find it in hot gas, dim red dwarf stars or even black holes. I NEVER thought that it would turn out to be something other than ordinary matter in an unusual form. Dark matter is so deeply confounding to me that I worry we will not discover its nature before I, myself, leave this world! Then again, there isnt a single generation of scientists that has had all its known puzzles neatly solved ‘just in time’. I’m just greedy!!!

5- Matter and Antimatter: During the Big Bang, there were equal amounts of matter and anti matter, but then for some reason all the antimatter dissappeared leaving us with only matter to form atoms, stars and galaxies. We don’t know why this happened, and the Standard Model is completely unhelpful in giving us any clues to explain this. But next to dark matter, this is one of the most outstanding mysteries of modern, 21st century cosmology. We have no clue how to account for this fact within the Standard Model, so again like Dark Matter, we see that at cosmological scales, the Standard Model is incomplete.

6- Origin of Time and Space: Understanding the nature of time and space, and trying to make peace with why they exist at all, is the bane of any physicists existence. I have written many blogs on this subject, and have tried to tackle it from many different angles, but in the end they are like jigsaw puzzels with too many missing pieces. Still, it is very exciting to explore where modern physics has taken us, and the many questions such thinking has opened up in surprising corners. My previous blog about ‘What is ‘Now’ is one such line of thinking. Many of the new ideas were not even imagined as little as 30 years ago, so that is a positive thing. We are still learning more about these two subjects and getting better at asking the right questions!

https://iopscience.iop.org/journal/0264-9381/page/Focus-issue-loop-quantum-gravity

7-Consciousness: OK…You know I would get to this eventually, and here it is! Neuroscientists know of lots of medical conditions that can rob us of consciousness including medical anesthesia, but why we have this sense about ourselves that we are a ‘person’ and have volition is a massively hard problem. In fact, consciousness is called the ‘Hard Problem’ in neuroscience..heck…in any science!

https://www.technologynetworks.com/neuroscience/articles/what-if-consciousness-is-not-what-drives-the-human-mind-307159

The ‘Soft Problem’ is how our senses give us a coherant internal model of the world that we can use to navigate the outside world. We know how to solve the Soft Problem, just follow the neurons. We are well on our way to understanding it thanks to high-tech brain imaging scanners and cleverly-designed experiments. The Hard Problem is ‘hard’ because our point-of-view is within the thing we are trying to undertand. Some think that our own ‘wet ware’ is not up to the task of even giving us the intelligence to answer this qustion. It will not be the first time someone has told us about limitations, but usually these are technological ones, and not ones related to limits to what our own brains can provide as a tool.

So there you have it.

My impression is that only Mysteries #1 and #2 will make huge progress. The Theory of Everything is in experimental disarray. For antimatter, there has been no progress, but many ideas. They all involve going outside the Standard Model. Dark matter might be replaced by a modification of gravity at galactic and cosmological scales.

Beyond these ‘superficial’ mysteries, we are left with three deep mysteries. The origin of space, time and consciousness remain our 21st century gift to children of the 22nd century!

Check back here in a few weeks for the next blog!

The End of Physics?

For 45 years I have followed the great pageant of ideas in theoretical physics. From high school through retirement, although my career and expertise is in astronomy and astrophysics, my passion has always been in following the glorious ideas that have swirled around in theoretical physics. I watched as the quark theory of the 1960s gave way to Grand Unification Theory in the 1970s, and then to string theory and inflationary cosmology in the 1980s. I was thrilled by how these ideas could be applied to understanding the earliest moments in the Big Bang and perhaps let me catch at least a mathematical glimpse of how the universe, time and space came to be literally out of Nothing; explanations not forthcoming from within Einstein’s theory of general relativity.

Even as recently as 2012 this story continued to captivate me even as I grappled with what might be the premature end of my life at the hands of non-Hodgkins Lymphoma diagnosed in 2008. And still I read the journal articles, watching as new ideas emerged, built upon the theoretical successes of the 1990s and beyond. But then a strange thing happened.

In the 1980s, the US embarked on the construction in Texas of the Superconducting Super Collider, but that project was scrapped and de-funded by Congress after ¼ of it had been built. Attention then turned to the European Large Hadron Collider project, which after 10 years finally achieved its first collisions in 2009. The energy of this accelerator has steadily been increased to 13 TeV, and now records some 600 million collisions per second, which generates 30 petabytes of data per year. Among these collisions were expected to be the traces of ‘new physics’, and physicists were not dissappointed. In 2012 the elusive Higgs Boson was detected some 50 years after it was predicted to exist. It was a major discovery that signaled we were definitely on the right track in verifying the Standard Model. But since then, following many more years of searching among the debris of trillions of collisions, all we continue to see are the successful predictions of the Standard Model confirmed again and again with only a few caveats.

Typically, physicists push experiments to ever-higher degrees of accuracy to uncover where our current theoretical model predictions are becoming thread-bare, revealing signs of new phenomena or particles, hence the term ‘new physics’. Theoreticians then use this anomalous data to extend known ideas into a larger arena, and always select new ideas that are the simplest-possible extensions of the older ideas. But sometimes you have to incorporate entirely new ideas. This happened when Einstein developed relativity, which was a ‘beautiful’ extension of the older and simpler Newtonian Physics. Ultimately it is the data that leads the way, and if not available, we get to argue over whose theory is more mathematically beautiful or elegant.

Today we have one such elegant contender for extending the Standard Model that involves a new symmetry in Nature called supersymmetry. Discovered mathematically in the mid-1970s, it showed how the particles in the Standard Model that account for matter (quarks, electrons) are related to the force-carrying particles (e.g. photons, gluons), but also offered an integrated role for gravity as a new kind of force-particle. The hitch was that to make the mathematics work so that it did not answer ‘infinity’ every time you did a calculation, you had to add a whole new family of super-heavy particles to the list of elementary particles. Many versions of ‘Minimally Supersymmetric Standard Models’ or MSSM’s were possible, but most agreed that starting at a mass of about 1000 times that of a proton (1 TeV), you would start to see the smallest of these particles as ‘low-hanging fruit’, like the tip of an upside-down pyramid.

For the last seven years of LHC operation, using a variety of techniques and sophisticated detectors, absolutely no sign of supersymmetry has yet to be found. In April, 2017 at the Moriond Conference, physicists with the ATLAS Experiment at CERN presented their first results examining the combined 2015 – 2016 LHC data. This new dataset was almost three times larger than what was available at the last major particle physics conference held in 2016. Searches for the supersymmetric partners to quarks and gluons (called squarks and gluinos) turned up nothing below a mass of 2 TeV. There was no evidence for exotic supersymmetric matter at masses below 6 TeV, and no heavy partner to the W-boson was found below 5 TeV.

Perhaps the worst result for me as an astronomer is for dark matter. The MSSM model, the simplest extension of the Standard Model with supersymmetry, predicted the existence of several very low mass particles called neutralinos. When added to cosmological models, neutralinos seem to account for the existence of dark matter, which occupies 27% of the gravitating stuff in the universe and controls the movement of ordinary matter as it forms galaxies and stars. MSSM gives astronomers a tidy way to explain dark matter and closes the book on what it is likely to be. Unfortunately the LHC has found no evidence for light-weight neutralinos at their expected MSSM mass ranges. (see for example https://arxiv.org/abs/1608.00872 or https://arxiv.org/abs/1605.04608)

Of course the searches will continue as the LHC remains our best tool for exploring these energies well into the 2030s. But if past is prologue, the news isn’t very promising. Typically the greatest discoveries of any new technology are made within the first decade of operation. The LHC is well on its way to ending its first decade with ‘only’ the Higgs boson as a prize. It was fully intended that the LHC would have given us hard evidence by now for literally dozens of new super-heavy particles, and a definitive candidate for dark matter to clean up the cosmological inventory.

So this is my reason for feeling sad. If the Higgs boson is a guide, it may take us several more decades and a whole new and expensive LHC replacement to find something significant to affirm our current ‘beautiful’ ideas about the physical nature of the universe. Supersymmetry may still play a role in this but it will be hard to attract a new generation of young physicists to its search if Nature continues to withhold so much as a hint we are on the right theoretical track.

If supersymmetry falls string theory, which hinges on supersymmetry, may also have to be put aside or re-thought. Nature seems to favor simple theories over complex ones so are the current string theories with supersymmetry really the simplest ones?

Thousands of physicists have toiled over these ideas since the 1970s. In the past, such a herculean effort usually won-out with Nature rewarding the tedious intellectual work, and some vestiges of the effort being salvaged for the new theory. I find it hard to believe that will not again be the case this time, but as I prepare for retirement I am realizing that I may not be around to see this final vindication.

So what should I make of my 45-year intellectual obsession to keep up with this research? Given what I know today would I have done things differently? Would I have taught fewer classes on this subject, or written fewer articles for popular science magazines?

Absolutely not!

I have thoroughly enjoyed the thrill of the new ideas about matter, space, time and dimension. The Multiverse idea offered me a new way of experiencing my place in ‘reality’. I could never have invented these amazing ideas on my own, which have entertained me for most of my professional life. Even today’s Nature seems to have handed us something new: Gravity waves have been detected after a 60-year search; detailed studies of the cosmic ‘fireball’ radiation are giving us hints to the earliest moments in the Big Bang; and of course we have discovered THOUSANDS of new planets.

Living in this new world seems almost as intellectually stimulating, and now offer me more immediate returns on my investment in the years remaining.

Glueballs anyone?

Today, physicists are both excited and disturbed by how well the Standard Model is behaving, even at the enormous energies provided by the CERN Large Hadron Collider. There seems to be no sign of the expected supersymmetry property that would show the way to the next-generation version of the Standard Model: Call it V2.0. But there is another ‘back door’ way to uncover its deficiencies. You see, even the tests for how the Standard Model itself works are incomplete, even after the dramatic 2012 discovery of the Higgs Boson! To see how this backdoor test works, we need a bit of history.

Glueballs found in a quark-soup (Credit: Alex Dzierba, Curtis Meyer and Eric Swanson)

Over fifty years ago in 1964, physicists Murray Gell-Mann at Caltech and George Zweig at CERN came up with the idea of the quark as a response to the bewildering number of elementary particles that were being discovered at the huge “atom smasher” labs sprouting up all over the world. Basically, you only needed three kinds of elementary quarks, called “up,” “down” and “strange.” Combining these in threes, you get the heavy particles called baryons, such as the proton and neutron. Combining them in twos, with one quark and one anti-quark, you get the medium-weight particles called the mesons. In my previous blog, I discussed how things are going with testing the quark model and identifying all of the ‘missing’ particles that this model predicts.

In addition to quarks, the Standard Model details how the strong nuclear force is created to hold these quarks together inside the particles of matter we actually see, such as protons and neutrons. To do this, quarks must exchange force-carrying particles called gluons, which ‘glue’ the quarks together in to groups of twos and threes. Gluons are second-cousins to the photons that transmit the electromagnetic force, but they have several important differences. Like photons, they carry no mass, however unlike photons that carry no electric charge, gluons carry what physicist call color-charge. Quarks can be either ‘red’, ‘blue’ or ‘green’, as well as anti-red, anti-green and anti-blue. That means that quarks have to have complex color charges like (red, anti-blue) etc. Because the gluons carry color charge, unlike photons which do not interact with each other, gluons can interact with each other very strongly through their complicated color-charges. The end result is that, under some circumstances, you can have a ball of gluons that resemble a temporarily-stable particle before they dissipate. Physicists call these glueballs…of course!

Searching for Glueballs.

Glueballs are one of the most novel, and key predictions of the Standard Model, so not surprisingly there has been a decades-long search for these waifs among the trillions of other particles that are also routinely created in modern particle accelerator labs around the world.

Example of glueball decay into pi mesons.

Glueballs are not expected to live very long, and because they carry no electrical charge they are perfectly neutral particles. When these pseudo-particles decay, they do so in a spray of other particles called mesons. Because glueballs consist of one gluon and one anti-gluon, they have no net color charge. From the various theoretical considerations, there are 15 basic glueball types that differ in what physicists term parity and angular momentum. Other massless particles of the same general type also include gravitons and Higgs bosons, but these are easily distinguished from glueball states due to their mass (glueballs should be between 1 and 5GeV) and other fundamental properties. The most promising glueball candidates are as follows:

Scalar candidates: f0(600), f0(980), f0(1370), f0(1500), f0(1710), f0(1790)
Pseudoscalar candidates: η(1405), X(1835), X(2120), X(2370), X(2500)
Tensor candidates: fJ(2220), f2(2340)

By 2015, the f-zero(1500) and f-zero(1710) had become the prime glueball candidates. The properties of glueball states can be calculated from the Standard Model, although this is a complex undertaking because glueballs interact with nearby quarks and other free gluons very strongly and all these factors have to be considered.

On October 15, 2015 there was a much-ballyhooed announcement that physicists had at last discovered the glueball particle. The articles cited Professor Anton Rebhan and Frederic Brünner from TU Wien (Vienna) as having completed these calculations, concluding that the f-zero(1710) was the best candidate consistent with experimental measurements and its predicted mass. More rigorous experimental work to define the properties and exact decays of this particle are, even now, going on at the CERN Large Hadron Collider and elsewhere.

So, between the missing particles I described in my previous blog, and glueballs, there are many things about the Standard Model that still need to be tested. But even with these predictions confirmed, physicists are still not ‘happy campers’ when it comes to this grand theory of matter and forces. Beyond these missing particles, we still need to have a deeper understanding of why some things are the way they are, and not something different.

Check back here on Wednesday, April 5 for my next topic!

Fifty Years of Quarks!

Today, physicists are both excited and disturbed by how well the Standard Model is behaving, even at the enormous energies provided by the CERN Large Hadron Collider. There seems to be no sign of the expected supersymmetry property that would show the way to the next-generation version of the Standard Model: Call it V2.0. But there is another ‘back door’ way to uncover its deficiencies. You see, even the tests for how the Standard Model itself works are incomplete, even after the dramatic 2012 discovery of the Higgs Boson! To see how this backdoor test works, we need a bit of history.

Over fifty years ago in 1964, physicists Murray Gell-Mann at Caltech and George Zweig at CERN came up with the idea of the quark as a response to the bewildering number of elementary particles that were being discovered at the huge “atom smasher” labs sprouting up all over the world. Basically, you only needed three kinds of elementary quarks, called “up,” “down” and “strange.” Combining these in threes, you get the heavy particles called baryons, such as the proton and neutron. Combining them in twos, with one quark and one anti-quark, you get the medium-weight particles called the mesons.

This early idea was extended to include three more types of quarks, dubbed “charmed,” “top” and “bottom” (or on the other side of the pond, “charmed,” “truth” and “beauty”) as they were discovered in the 1970s. These six quarks form three generations — (U, D), (S, C), (T, B) — in the Standard Model.

Particle tracks at CERN/CMS experiment (credit: CERN/CMS)

Early Predictions

At first the quark model easily accounted for the then-known particles. A proton would consist of two up quarks and one down quark (U, U, D), and a neutron would be (D, D, U). A pi-plus meson would be (U, anti-D), and a pi-minus meson would be (D, anti-U), and so on. It’s a bit confusing to combine quarks and anti-quarks in all the possible combinations. It’s kind of like working out all the ways that a coin flipped three times give you a pattern like (T,T,H) or (H,T,H), but when you do this in twos and threes for U, D and S quarks, you get the entire family of the nine known mesons, which forms one geometric pattern in the figure below, called the Meson Nonet.

The basic Meson Nonet (credit: Wikimedia Commons)

If you take the three quarks U, D and S and combine them in all possible unique threes, you get two patterns of particles shown below, called the Baryon Octet (left) and the Baryon Decuplet (right).

Normal baryons made from three-quark triplets

The problem was that there was a single missing particle in the simple 3-quark baryon pattern. The Omega-minus (S,S,S) at the apex of the Baryon Decuplet was nowhere to be found. This slot was empty until Brookhaven National Laboratory discovered it in early 1964. It was the first indication that the quark model was on the right track and could predict a new particle that no one had ever seen before. Once the other three quarks (C, T and B) were discovered in the 1970s, it was clear that there were many more slots to fill in the geometric patterns that emerged from a six-quark system.

The first particles predicted, and then discovered, in these patterns were the J/Psi “charmonium” meson (C, anti-C) in 1974, and the Upsilon “bottomonium” meson (B, anti-B) in 1977. Apparently there are no possible top mesons (T, anti-T) because the top quark decays so quickly it is gone before it can bind together with an anti-top quark to make even the lightest stable toponium meson!

The number of possible particles that result by simply combining the six quarks and six anti-quarks in patterns of twos (mesons) is exactly 39 mesons. Of these, only 26 have been detected as of 2017. These particles have masses between 4 and 11 times more massive than a single proton!

For the still-heavier three-quark baryons, the quark patterns predict 75 baryons containing combinations of all six quarks. Of these, the proton and neutron are the least massive! But there are 31 of these predicted baryons that have not been detected yet. These include the lightest missing particle, the double charmed Xi (U,C,C) and the bottom Sigma (U, D, B), and the most massive particles, called the charmed double-bottom Omega (C, B, B) and the triple-bottom omega (B,B,B). In 2014, CERN/LHC announced the discovery of two of these missing particles, called the bottom Xi baryons (B, S, D), with masses near 5.8 GeV.
To make life even more interesting for the Standard Model, other combinations of more than three quarks are also possible.

Exotic Baryons
A pentaquark baryon particle can contain four quarks and one anti-quark. The first of these, called the Theta-plus baryon, was predicted in 1997 and consists of (U, U, D, D, anti-S). This kind of quark package seems to be pretty rare and hard to create. There have been several claims for a detection of such a particle near 1.5 GeV, but experimental verification remains controversial. Two other possibilities called the Phi double-minus (D, D, S, S, anti-U) and the charmed neutral Theta (U, U, D, D, anti-C) have been searched for but not found.

Comparing normal and exotic baryons (credit: Quantum Diaries)

There are also tetraquark mesons, which consist of four quarks. The Z-meson (C, D, anti-C, anti-U) was discovered by the Japanese Bell Experiment in 2007 and confirmed in 2014 by the Large Hadron Collider at 4.43 GeV, hence the proper name Z(4430). The Y(4140) was discovered at Fermilab in 2009 and confirmed at the LHC in 2012 and has a mass 4.4 times the proton’s mass. It could be a combination of charmed quarks and charmed anti-quarks (C, anti-C, C, anti-C). The X(3830) particle was also discovered by the Japanese Bell Experiment and confirmed by other investigators, and could be yet another tetraquark combination consisting of a pair of quarks and anti-quarks (q, anti-q, q, anti-q).

So the Standard Model, and the six-quark model it contains, makes specific predictions for new baryon and meson states to be discovered. All totaled, there are 44 ordinary baryons and mesons that remain to be discovered! As for the ‘exotics’ that opens up a whole other universe of possibilities. In theory, heptaquarks (5 quarks, 2 antiquarks), nonaquarks (6 quarks, 3 antiquarks), etc. could also exist.

At the current pace of a few particles per year or so, we may finally wrap up all the predictions of the quark model in the next few decades. Then we really get to wonder what lies beyond the Standard once all the predicted particle slots have been filled. It is actually a win-win situation, because we either completely verify the quark model, which is very cool, or we discover anomalous particles that the quark model can’t explain, which may show us the ‘backdoor’ way to the Standard Model v.2.0 that the current supersymmetry searches seem not to be providing us just yet.

Check back here on Wednesday, March 22 for the next topic!