Beyond the Standard Model of particle physics - a wild wild world…

in StemSocial9 months ago

Hi everyone, and welcome to my last blog for this year. I am about to drive to Brussels (Belgium) for a couple of days, before calmly coming back to France for the end of the holidays. In the meantime, here is a fresh blog about why the high-energy physics community is working for decades on new phenomena beyond the Standard Model of particle physics.

In the post of two weeks ago, I discussed how the Standard Model has been constructed brick by brick, or in other words how it has been built elementary particle by elementary particle. The post of last week was then dedicated to the Higgs boson, from the reasons why it has been added to the theory to its discovery a few years ago and the searches that will continue for possibly 100 years.

High-energy physicists hence rely on a very successful framework (i.e. the Standard Model), that provides not only an explanation for all high-energy physics data recorded so far but also predictions for all current and future experiments. However, physicists are generally rather excited by what is generally coined ‘beyond the Standard Model physics’, or new physics for short. This ‘new physics’ includes possible new phenomena predicted by theories extending the Standard Model of particle physics. These are in addition targeted quite deeply experimentally (in particular at the Large Hadron Collider at CERN).

Of course, the Standard Model works like a charm, as mentioned quite a few times in my last two blogs. For this reason, we are concerned with extensions of the Standard Model that are usually built on top of the Standard Model. In other words, we can see the Standard Model as the tip of an iceberg that we try to probe fully.

In the present post, I will try to answer why we are quite convinced that there must be some new physics somewhere, hopefully not too far behind the corner. In fact, this post will summarise the main motivations of a large part of my research work of the last 20 years.

It is however impossible to detail all the limitations and conceptual issues we may have with the Standard Model. For that reason, I subjectively decided to focus on what I personally consider as the main reasons why the Standard Model is only a milestone of the journey leading to a better understanding of how the universe works. I will then briefly mention a few other items in the last part of this blog (and will be happy to come back to this in the comment section).


[Credits: Fermilab]


Neutrino masses


In the post of two weeks ago, I detailed how we came up with a Standard Model that contains three species of neutrinos (the electron neutrino 𝞶e, muon neutrino 𝞶𝝁 and tau neutrino 𝞶𝜏). All these three neutrinos have been experimentally confirmed today, although in the case of the tau neutrino the task was not so easy.

The neutrinos are indeed the most elusive of all known particles. This originates from their very weakly-interacting nature. They are so weakly interacting that 1,000,000,000,000 neutrinos just go through any human being of the planet without doing anything… every second!

However, even if they rarely interact with anything, neutrinos have been observed in a variety of processes, and some of their properties have been determined quite well. From these properties, neutrinos are expected to be massless particles. There is nothing wrong with this, with the exception that neutrinos have been found to oscillate into each other when they propagate, as illustrated in the figure below. This observation was by the way rewarded with the Nobel Prize in physics in 2015.

This means that if we have a beam with neutrinos of a single species and if we send that beam somewhere located hundreds or thousands kilometres away (such a distance is needed by the weakly-interacting nature of neutrinos), we will end up with a beam containing neutrinos of all three types.


[Credits: J-Parc]

For instance, let’s assume we have a beam of electron neutrinos that is produced in a place A, and that we send this beam a thousand miles away to another location B. If we investigate the content of the beam in B, we will find that it still dominantly comprises electron neutrinos. However, muon neutrinos and tau neutrinos will also be present in the beam.

But are neutrinos oscillations a real problem for the Standard Model? The answer is ‘yes, yes, yes! Neutrino oscillations are only possible if neutrinos are massive. Neutrino masses are therefore a fact (as neutrino oscillations have been observed), and this fact contradicts the Standard Model.

Neutrinos hence consist in the best motivation for extending the Standard Model. We could argue that we could just use the Higgs boson as for the masses of any other particle. However, from the known properties of neutrinos, we cannot simply rely on the Higgs boson to equip them with a mass.

A generalisation of the Standard Model is needed to make neutrinos massive. The most famous mechanism that yields neutrino masses is the so-called seesaw mechanism. I won’t enter into details about this (this is probably worth a full post), but the important point is that this requires new particles beyond the Standard Model.

Neutrino physics consists thus in a significant part of the search program at the Large Hadron Collider, as there is a potential for observing new particles or their effects in present or future data. On my side, I only started to get excited and work on this subject about two years ago, so that I have only a couple of publications on it. I expect to blog about them in 2022 ;)


Dark matter


Another very good motivation to study extensions of the Standard Model is dark matter. Before detailing why, let’s focus 5 minutes on standard cosmology. The latter states that not all matter in the universe is expected to be in a visible form (in the sense that it can emit, absorb or reflect light).

It in fact turns out that 85% of matter is of a dark nature. Why do we think that there is such a thing of dark matter? There are actually several indirect hints pointing to this (I will come to the indirectness of the proofs below).

The origins of dark matter as we know it comes from the work of Zwicky in the 1930s, when he postulated dark matter to explain the observed motion of stars in a distant galaxy. 90 years ago, Zwicky measured the speed of stars as a function of their distance to the galactic centre. By means of standard classical mechanics, the same speed of stars could also be calculated from two ingredients: the way gravity works (which is very well known) and the amount of (gravitationally-interacting) visible matter.

The results obtained through observations and through calculations were however exhibiting a strong mismatch. Zwicky then proposed that some invisible massive stuff should be around. With more massive objects, classical calculations would yield a different result, and agreement between theory and data could be restored.

This idea was confirmed 30-40 years later through the work of Vera Rubin on various galaxies. She provided not only the first (quantitative) indirect evidence for dark matter, but also confirmed that dark matter was dominant over visible matter.


[Credits: ESA (CC BY-SA IGO 3.0)]

The dark matter story does not end there. We indeed have many additional pieces of evidence, so that most physicists are convinced that dark matter is real.

For instance, dark matter is a necessary component of the universe to explain cosmic microwave background data as observed by the Planck collaboration. To discuss this a bit, we can start with a brief definition of the cosmic microwave background. The latter consists of the fossil radiation left from the Big Bang.

The cosmic microwave background is known to have an average temperature of 2.72 degrees Kelvin (that is -270.42 degrees Celsius). However, the radiation temperature is not constant all over the universe. An average is an average after all. The temperature spectrum hence exhibits patterns with small variations. What is really cool is that the analysis of the structure of the variations strongly supports standard cosmology, that includes and dark matter.

As a last example for motivations for dark matter (among others which I won’t discuss to avoid this post to explode in length), we can also mention that dark matter is a necessary ingredient to explain the formation of galaxies. Without dark matter, simulations of the life of our universe cannot manage to obtain a universe as we see it today, with its stars, galaxies and clusters of galaxies. More gravitationally-interacting matter is always needed…

However, all the above proofs for dark matter are indirect, and we are still missing any direct observation of dark matter. The latter is expected to be obtained either through experiments monitoring the interaction of dark matter when it hits the planet (like at the Xenon1t experiment in Italy), or at colliders (such as the Large Hadron Collider at CERN).

This being said, we can go back to the Standard Model and the fact that it should include some elusive dark matter particle. The problem is that no elementary particle of the Standard Model can play this role. Incorporating a dark matter candidate in the theory hence automatically leads to a physics framework beyond the Standard Model, generally with a nice set of expected new phenomena.

Personally, the problematics of dark matter is crucial for my research. For this reason, I used to write quite a lot of blogs about this topic back in the days. This won’t be very different, but from next year!


The hierarchy problem


Now, let’s move away from the two problems of the Standard Model relative to data that I have discussed so far. Instead, let’s approach more conceptual limitations. The one I want to focus on is the so-called hierarchy problem.

It is called that way because there is an important hierarchy between two quantities, that are the two energy regimes relevant for the Standard Model. For the rest of the discussion, I recall that in high-energy physics, masses and energies are all measured in GeV, where 1 GeV is taken equal to the proton mass (or the mass of a hydrogen nucleus).

The first energy regime relevant for the Standard Model is connected to the masses of the W and Z bosons. These two masses are roughly the same: 100 GeV. This is what is defined as the electroweak scale.

As I have never introduced what the ‘electroweak theory’ was, let me simply state that this is the theoretical framework in which electromagnetism and weak interactions are unified. It is fully included in the Standard Model, and it is also good to mention that the electroweak regime is the regime currently probed at the Large Hadron Collider at CERN.

The second relevant energy regime is associated with the Planck scale, that is equal to 1019 GeV (or 10,000,000,000,000,000,000 GeV). At such a scale gravitational effects are important and must be accounted for. Gravity is however not included in the Standard Model, not only because at more reasonable energy scales associated effects are negligibly small, but also because we do not know how to do so.

The theory must thus be modified at the Planck scale so that gravity could be embedded. A community of people is working on this issue, that consists of a field of research on its own. Discussing this is however not the purpose of this blog.


[Credits: OLCF (CC BY 2.0)]

What we can say so far is that the electroweak scale is a scale of 100 GeV, and the Planck scale is a scale that is 100,000,000,000,000,000 times higher. We thus have a huge difference between the two scales. This difference, or hierarchy, leads to problems that could even sometimes be seen as a paradox. The reason is that the Standard Model is a quantum framework.

The quantum nature of the Standard Model has strong implications for the calculation of predictions for any measurable quantity. Those predictions must indeed include a large set of quantum correction effects. We could calculate these corrections, for instance, for the ‘size of the Higgs field’. I won’t enter into details, but for the purpose of this blog we can just keep in mind that the size of the Higgs field is what dictates the order of magnitude of the masses of the W and Z bosons.

The size of the Higgs field therefore lies around 100 GeV, or at the electroweak scale. When we consider quantum correction effects, the size of the Higgs field is however sent to 10,000,000,000,000,000,000 GeV (i.e. the Planck scale). This is a catastrophe, that can be avoided in two ways.

On the one hand, we could fix the two dozens of parameters of the Standard Model up to their 30th figure, so that quantum corrections would involve some miraculous cancellations and be all fine. This is however very unsatisfactory. Changing the 30th digit of any parameter would indeed send back the size of the Higgs field to the Planck scale… It is hard to believe that nature would be so nasty with us, forcing us to determine experimentally each parameter up to 30 figures (which we won’t be able to do anyways)!

On the other hand, we can consider the hierarchy problem as emerging from the fact that the Standard Model does not include all the elementary building blocks of nature: new particles must still be discovered. The impact of those particles on the quantum corrections will provide the desired cancellation. The cancellation could arise, for instance, by postulating some symmetry between the already-discovered and not-yet-discovered particles.

The second option is of course the preferred one in the high-energy physics community: the hierarchy problem results from the fact that only a subset of the full theory has been discovered so far.

Most frameworks extending the Standard Model and addressing the hierarchy problem hence generally include new particles to be discovered. In addition, the size of the Higgs field explains why those new particles are expected to lie not too far away from the electroweak scale. Since this is the energy regime probed at the Large Hadron Collider, we expect new phenomena to be observed in data soon. Data however still hides them from us at the present time (up to some intriguing anomalies).


The failures of the Standard Model as motivations to go beyond


I have so far focused on three reasons motivating theoretical and experimental studies of extensions of the Standard Model. I considered the problematics of dark matter, the fact that neutrinos are massive and the issue of the hierarchy between the electroweak and the Planck scales. Those three reasons are those that I consider as the most important ones to justify going beyond the Standard Model. There are however much more than three reasons in total.

  • Unification: In the Standard Model only two out of the three fundamental interactions are unified (electromagnetism and weak interactions). We need to generalise the theory to be able to unify also the strong force.
  • Gravity: There is a fourth fundamental interaction, gravity, that it is not included in the Standard Model. As mentioned above in this blog, embedding gravity consistently is a whole field of research.
  • Three families: There are three neutrinos, three charged leptons and two sets of three quarks (a given set of three quarks having identical properties). Why three?
  • What is the true nature of dark energy, the latter being needed to explain the accelerated expansion of the universe.
  • Where is antimatter gone? Only matter is present today.
  • Why do we live in a four-dimensional spacetime? Could there be extra dimensions?

And this list is far from being over. We can really find tens of motivations to study beyond the Standard Model physics. Physicists are hence strongly confident that the Standard Model is not the end of the story. Accordingly, beyond the Standard Model physics is a very active field of research, dozens of new scientific articles appearing every single working day of the week (this is a fact!).

In this blog, I have tried to introduce these different reasons that also justify my own research work. I am a theorist whose research consists of trying to understand what new physics beyond the Standard Model could be or could not be in the light of data. I also investigate (and sometimes design) new ways to look for new phenomena. Hopefully, this will contribute (through little steps of course) to the work of the high-energy physics community to improve our understanding of the universe.

We should also note that there are always new things that can be learned in this process of improving our vision of the world, which I find quite amazing. As a researcher, we are somehow eternal learners!

It is now time to end this blog, which is probably a bit too long as usual. Feel free to ask anything in the comment section (clarifications, questions, suggestions, etc.), and to also propose topics for the next blogs if you want to.

As last words, I wish everyone on STEMsocial and on Hive happy holidays. See you all in 2022, at least for new blogs on particle physics and cosmology!

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Why three?

This is the thing I don't understand 🤣 Why not one that something split into three different versions?

Where is antimatter gone?

Correct me if I'm wrong, now we can produce antimatter, even if it is in very small quantities, it doesn't help to understand if there is still antimatter somewhere, where is it? Or to hunt Dark Matter?

For the last one, an example to better understand: Can't we think of a system using matter and antimatter creating a tunnel for dark matter or a dark matter catcher, like on one side matter and antimatter on the other the both just spaced the necessary distance so that they don't interact (just the size we estimate for the antimatter)? Or a system similar to atom laser cooling but this time using antimatter?

if you understood me you are extremely well skilled! Even me when I read it again, I have a hard time.

I know I think I am a scientist without having the knowledge to do it, but it's so fun that I want my part of it 🤣

 9 months ago  

Thanks a lot for your questions/comments. This is the kind of reactions to my blogs I like the most.

Why not one that something split into three different versions?

In terms of quantum fields (which is the relevant framework here), we actually have a single field that carries a 'generation index' (or family index) running from 1 to 3. In this sense, we already have a single entity with three facets. Is it what you had in mind with your question?

Correct me if I'm wrong, now we can produce antimatter, even if it is in very small quantities, it doesn't help to understand if there is still antimatter somewhere, where is it? Or to hunt Dark Matter?

You are correct. Antimatter can be produced (and it is today bread and butter). However, stable antimatter is another story. As long as it is produced, antimatter particles must be prevented from being in contact with matter. Otherwise, they will annihilate.

We nevertheless manage to produce antimatter and keep it as such during sufficiently long time to study its properties. For instance, various experiments are running at CERN around the ELENA project.

For the last one, an example to better understand: Can't we think of a system using matter and antimatter creating a tunnel for dark matter or a dark matter catcher, like on one side matter and antimatter on the other the both just spaced the necessary distance so that they don't interact (just the size we estimate for the antimatter)? Or a system similar to atom laser cooling but this time using antimatter?

This I didn't follow fully. Can you elaborate a little on the link with dark matter? I will try to answer but I may be off topic. So feel free to come back to me if necessary.

In principle, we could have antimatter beams (like at the LEP or Tevatron colliders mentioned in my previous post). From there, we could smash the two beams, and hope to observe new phenomena like in any accelerator facility.

if you understood me you are extremely well skilled! Even me when I read it again, I have a hard time.

This time, as said above: no :D

I know I think I am a scientist without having the knowledge to do it, but it's so fun that I want my part of it 🤣

Having fun is the most important aspect! I agree with this! For the rest, just ask any question you may have!

Is it what you had in mind with your question?

Yes, totally, thanks for your answer

antimatter particles must be prevented from being in contact with matter

I thought we were able to do this by using electromagnetic fields so that there is no contact with the matter.

Thanks for the link to ELENA Project

Can you elaborate a little

My main idea was that if we can't do it with matter try it with antimatter or both Hahaha.

If I develop, I was thinking if we can create a space between both (matter and antimatter without contact or interaction), neutral like Switzerland, if the dark matter passes inside maybe it will have a reaction somewhere (on matter side, antimatter side, or both) due to an oscillation of the dark matter or another cause?

For the laser part after thinking of it I probably take the wrong way because we are at the atom level and not the particle, it means nothing can be done with it before finding the particle of the dark matter (if it's a particle as we understand it) and probably after too because I don't think that dark matter will be a constituent of something similar to an atom.

Having fun is the most important aspect!

I know that it's a lot of work with a lot of data 90% of the time but if one day it will have a particle or model named @lemouth it will be very fun 👍

 9 months ago  

I thought we were able to do this by using electromagnetic fields so that there is no contact with the matter.

Electromagnetic fields are exactly what we use to trap antimatter. However, antimatter is not trapped forever. If I am not wrong, it can only be trapped for at most 1/4 of an hour (that's the record, but I may need a little update here). See here for instance, which confirms what I had on the top of my head.

To discuss your proposal for dark matter, this is exactly what is done today... but with matter only. Here, heavy nuclei are used (like Xenon). For what concerns antimatter, we only deal with anti-hydrogen for now, and this won't work for sure as hydrogen or anti-hydrogen are both too light.

One crucial point that is probably killing your proposal is that dark matter needs to pass through the detector material to interact with it. Note that we have atoms in the detector but dark matter can interact with their nuclei only (via fundamental interactions with quarks and gluons), or even with their electrons. So that this specific item does not matter much.

Please let me know whether this clarifies. Cheers!

thank you for all your answers, clarifications, and reading links to keep me busy :)

 9 months ago  

You are very welcome. Be ready to be even busier in a close future :D

I was going to say that I can't understand how something that has no mass can interact with anything, but then you said neutrinos actually do have a mass! If I understand correctly.

Is there any physical particle that exists without having a mass? (And does Higgs give it/them a mass?)

If matter has anti-matter, does dark matter have anti-dark matter?

Science is probably in its infancy, even with all the wonders it has produced, so I would say that yeah the Standard Model will be replaced, and then whatever replaces it will be replaced....

 9 months ago  

I was going to say that I can't understand how something that has no mass can interact with anything, but then you said neutrinos actually do have a mass! If I understand correctly.

The fact that neutrinos are massive or massless plays no role in the way they interact. Neutrinos are only sensitive to the weak force, whose 'strength' is not related to mass. In fact, only the strength of gravity is connected to mass. For the other three interactions, we have different 'charges' (in the general sense). For instance, for electromagnetism this would be the electric charge (and not the mass)

Is there any physical particle that exists without having a mass? (And does Higgs give it/them a mass?)

Photon and gluons that respectively mediate the electromagnetic and the strong force are massless particles. While the Higgs boson interacts with photons and gluons, these interactions are a bit special so that they are not proportional to the masses of the involved particles.

Photons and gluons are hence really massless (this is also a prediction of the Standard Model).

If matter has anti-matter, does dark matter have anti-dark matter?

Yes or no. This depends on how dark matter is included in the theory. It could be its own antiparticle, or not. In fact, it is not even clear that neutrinos and anti-neutrinos are not the same thing. Both options are allowed by data for now.

Science is probably in its infancy, even with all the wonders it has produced, so I would say that yeah the Standard Model will be replaced, and then whatever replaces it will be replaced....

Isn't it how science has been built from the early days? :D

Interesting. Perhaps I need to study what physicists mean by 'mass', because right now I'm having a hard time understanding how something without a mass can exist in time and space. I often find that the best way (for me) to understand something difficult in science, is to read what philosophers have to say about it! E.g. just found a book that's only about mass and its history: https://press.princeton.edu/books/paperback/9780691144320/concepts-of-mass-in-contemporary-physics-and-philosophy

So maybe I'll read that in the future. But I worry that by the time I do, scientists will have changed their models!

 9 months ago  

I don't know how to explain this better. Sorry.

The way those massless particles behave is entirely dictated by special relativity, so that this is by far non trivial (and not high-school level). Those particles for instance travel at the speed of light. Moreover, they feel gravitational fields (that's general relativity), even with being massless, etc.

The story is far from trivial, as can be guessed. The point that can maybe make it clearer (who knows?) is to recall that we discuss at the level of the microscopic world and not the macroscopic one. Things are very different in there.

Very detailed explaination! I may not have a wide and deep understanding of this topic, however, it is an interesting reads and really appreciate the effort you've spent in this post. Have a great holiday and enjoy @lemouth :))

 9 months ago  

Thanks a lot for your message. Please do not hesitate to ask for clarifications if needed. In the meantime, I wish you a happy holiday time as well.

Cheers!

Great post and another interesting read on one of my favorite topics. Wishing you happy holidays!

 9 months ago  

Thanks a lot! Happy holiday to you as well!

Concerning your suggestions in the other comment, I was not considering writing about black holes in a close future, even if I have attended a few interesting seminars on this topic recently. I am in any case adding them to the list of topics, but I cannot tell you when this will be programmed. This is related to the outcome of an intense debate between me and myself ;)

For virtual particles, can you tell me exactly what you have in mind. Is it related to virtual particles in quantum field theory, as for instance when a given initial state comprising a particle-antiparticle pair annihilates into a virtual photon to give rise, for example, to a final state comprising a muon-antimuon pair?

Totally up to you on what you want to write about. I was thinking maybe something maybe the history of the idea, the Casimir effect, how it relates to vacuum state energy, and quantum field theory

 9 months ago  

All of this is noted! Thanks! Then we will see (note that my list includes more than 100 potential topics at the moment ;) ).

Also, maybe a topic of black holes and/or virtual particles?

We should also note that there are always new things that can be learned in this process of improving our vision of the world, which I find quite amazing. As a researcher, we are somehow eternal learners!

That explain why we have to search and search again. That's exactly what research means. I wish you a happy holiday sir.

 9 months ago  

Yes. As soon as one question is answered, we always come up with new questions and new paths to follow to improve our knowledge of the world around us.

Happy holiday to you as well!

 9 months ago  

2021 has been memorable...

I think I now have bit of Better understanding of this neutrino.

Happy holidays...it's that time of the season again.

 9 months ago  

Thanks a lot for passing by! 2021 has been memorable and a very hard year. Hopefully 2022 will be smoother.

I am happy to read that you liked the neutrino part of this blog. Feel free to ask me anything about anything that would appear as too obscure.

Happy holidays!! See you in 2022
This is the first time I'm hearing about a neutrino, interesting! I'm curious though, if neutrinos are massless, basically does not contribute to matter cause matter is anything that has weight and occupies space yeah? What exactly is its significance to nature🙁

 9 months ago  

Thanks a lot for your question. It is a very good one. I will give one answer, and one comment. I hope this will clarify the situation.

You are right when you say that matter is massive. This is indeed how it is defined (for instance in the dictionary). Now, at the most fundamental level we find atoms and their constituents. The latter comprise quarks and electrons, as detailed in this post. All those elementary particles are massive (although quarks and electrons only contribute to a small fraction of the masses of atoms; let's however discuss this specific point later if you are interested in it, as this is only weakly connected to the question).

In contrast, even if neutrinos are said to belong to the 'matter sector' of the Standard Model, they are not components of atoms. They appear in a variety of processes and then escape freely. For this reason, they can be either massive or massless. It is thus more a matter of vocabulary to call them 'matter particles'.

Finally, note that mass is an intrinsic property of an object (arising from its constituents in the case of a composite object). On the other hand, weight is a force that has for origin gravity. For instance, on Earth weight will be the effect of the gravitational field of the planet on a mass. The same mass will hence have a different weight on the Moon.

Again, thanks for passing by and happy holiday!

It is now time to end this blog, which is probably a bit too long as usual.

A long article indeed! It took me many times to read before I could digest the little part, this particle physics is what I have read for a very long time and thank God you are back to fill the gap. We will be expecting more simpler to read and digest update on the field. Thanks and guess you are already enjoy your holiday

 9 months ago  

I decided to stop writing smaller articles (as I did before the pandemic), because I actually don't like that. Such articles do not indeed provide me enough space to give enough details, yielding automatically poorer and less understandable descriptions.

I know I may risk to lose people because of the length... but I take that risk. Clarity is my prime concern, and sometimes, it is hard by virtue of the topic itself even within a long blog (my experience being what it is). I however do my best, now without paying attention to space.

To rephrase @mathowl: writing in a way I like ensures that at least one person will like my write-ups (me ;) ).

Please continue and never mind, just that it has been long I read such a long article on Hive. By making it interesting like you are doing will surely make people, especially the major in the area enjoy it more.

Looking forward for the update next year on particle physics and cosmology

 9 months ago  

On Jan 3rd, if everything works as planned ;)

Thank heavens for Distilled. Where have I been? I missed this. But here I am. As I read this blog I find my understanding builds on previous blogs you have written. I understand how the Standard Model doesn't answer all the questions about the nature of the universe. There are contradictions between the theory and observation--ex: neutrinos are supposed to be massless and yet oscillate into each other so must have mass. To those of us who read your reports from the world of theoretical physics, it seems you are on the frontier as the early nineteenth century scientists were on the frontier of nuclear science (radioactivity, structure of the atom, and on and on). Observations, that lead to questions, that lead to observations...

I think there will never be an end to the questions. After all, it is they mystery of the universe (of existence itself?) you explore. Thank you for another illuminating blog.

 9 months ago  

I was indeed a bit surprised that you didn't comment the blog of this week. I am glad to see that finally you managed to find it! ;)

Your summary of the post is totally correct!

I think there will never be an end to the questions. After all, it is they mystery of the universe (of existence itself?) you explore. Thank you for another illuminating blog.

That's the whole purpose of science: asking questions, then finding answers, which next leads to more questions! That's a virtuous cycle, somehow.

Moreover, I would like to emphasise the usage of the word explore (similarly as in the discussion following a comment of @duke77 in the French version of this post). We are at a level where we need to explore beyond where we are, to understand better what is going on. The excitement is that there is no way to know where exploration will lead us (and when it will lead us somewhere).

As you know, my training is in the social sciences, liberal arts. As such, I am more likely to see the adventure and creativity in your theoretical studies than someone might who is trained in the 'hard' sciences.

One of the most charming aspects of your posts (yes, charming!) is the excitement you convey for your research. This is contagious--essential in a good teacher. You are that. A theoretical physicist who opens the universe, just a little at a time, for the rest of us.

Have a great holiday break with your family.

 9 months ago  

Thanks for this feedback. I have very little of comments of this kind, and they really please me! ;)

Have a happy holiday time as well!

 9 months ago  

Interesting submission and, deservedly, it sparked up some genuine engagement. You should perhaps be posting more. Your Hive audience on this particle thing would have grown to a large extent had it been that you don't usually take a long break off writing. Keep them coming!

 9 months ago  

Unfortunately, I cannot write more than one such a post per week. It indeed requires some time to be written. Moreover, handling the comments also takes some time. I have to share my time resources between my job (that takes easily 60 hours per week), my family (to which I am happy to dedicate most of my free time) and STEMsocial/Hive (that amounts for a few hours spread all over the week).

I thus definitely cannot deal with even two posts like that per week. Note that there is also an adaptation in French appearing 3 days later. I hence prefer writing one post per week and doing it right, over writing more and being a bit more sloppy or not engaging as much with the readers. I hope such posts will provide, on the long term, motivation for people outside Hive to come, and consume information available here in one way or the other.

 9 months ago  

I am not sure sure why but I never enjoyed particle physics...

What is a nice introduction to particle physics for a mathematician?

 9 months ago  

Mmmh, here I would start with quantum fields and symmetries. This is purely mathematical and so mathematicians may enjoy it. For instance, in my habilitation thesis I introduce supersymmetry and its phenomenology from spin-statistics and Noether theorems, the first part of the thesis being purely theoretical and not phenomenological at all. Maybe would a mathematician like it (if you are interested, it is open access, available from here)?

 9 months ago  

I will have a look at it :3

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 8 months ago  

And... ?

and I am linking two interesting articles about particle physics, nothing more!
You are not listing our (or should I say mine) poor understanding of the nature of time in the list of the limits to the Standard model?

 8 months ago  

and I am linking two interesting articles about particle physics, nothing more!

Thanks. However, I actually see only one article, and it is a condensed matter article (which seems interesting, although I sadly cannot access it as it is not open access).

You are not listing our (or should I say mine) poor understanding of the nature of time in the list of the limits to the Standard model?

No I didn't. In the same way I haven't listed many other questions/issues.

Cheers!