Is the SM of particles physics and Cosmology SM

[Arthur Lopes]

I'm in a deep discussion with a friend. He says that the Standard Model of particle physics is actually known by Standard Model of cosmology and that both are the same and that the SM of particle physics is in the Minkousky geometry... I disagree about this, I do think that the SM of particle physics is one thing and the SM of cosmology is another, and even if the SM of cosmology includes the SM of particle physics and applies it to concepts like geometry, they are different.
Who is wrong? Or better, what's is the truth?

 

[Orodruin]

The Standard Model of cosmology is the ΛCDM model. It is not the same as the SM of particle physics.

 

[Arthur Lopes]

The Standard Model of cosmology is the ΛCDM model. It is not the same as the SM of particle physics.

Thanks for the insight Orodruin!
I have two more questions: Does the SM of particle physics have a geometry? Like Minkousky or Godel? or these things are from cosmology?
Do you have articles or textbooks about SM and models BSM to recommend?
Thanks!

 

[Orodruin]

The SM of particle physics is a quantum field theory and is usually considered in Minkowski space. This is generally a good enough approximation.

 

[Arthur Lopes]

The SM of particle physics is a quantum field theory and is usually considered in Minkowski space. This is generally a good enough approximation.

Thanks a lot for everything!
Can you or someone give me a help about what disciplines I have to take to be able to understand at least a little of the mathematics in the SM and the models from BSM, like extra dimensions? Linear algebra? Calculus? Which topic of it?
I'm having a little hard time to understand the theory behind particle physics.
Thanks again!

 

[Orodruin]

In order to understand the SM on a level that is sufficient to actually perform computations you will need:

• Linear algebra
• Multivariable calculus
• Ordinary and partial differential equations
• Transform and series methods
• Group theory
• At least a couple of courses on quantum mechanics
• Special relativity
• Quantum field theory

Note that this is a descriptive list. The points may or may not correspond to actual courses at your university and I might have missed something.

 

[Carlos L. Janer]

I don't really understand why cosmologists use the SM of particle physics. Shouldn't they try to express it in a FRW curved spacetime? Can this generalization be done? It's difficult for me to understand why the SM is actually used to speculate about the physical laws of the early Universe.

 

[ChrisVer]

Shouldn't they try to express it in a FRW curved spacetime?

I guess that is not necessary, since (when you use the SM of particle physics in cosmology) the particles interact locally... you don't really see what the interactions between two particles that are separated at cosmo-scales are. Locally everything can be seen pretty flat, as the Earth is flat as long as your communication with your friends (physical) is concerned. It is the same reason why SM of particle physics works on the Earth (which strictly speaking does not have a Minkowski spacetime around it).
For a scalar field in the very early universe (inflaton) I've seen they use GR.

the models from BSM, like extra dimensions?

Extra dimensions can be learned with topology and geometry (GR).

 

[mfb]

I don't really understand why cosmologists use the SM of particle physics.

They do not, as Orodruin explained in post #2 already.

For the very early universe, both standard models are combined: space is locally flat to a good approximation, so you can study the particle interactions with the particle physics SM while the scale factor of the universe evolves with the cosmology SM.

 

[Carlos L. Janer]

I wasn't thinking about particle interactions. What I had in mind is the vacuum state and how its energy content affects the expansion of the universe.

The Lagrangian density could, in principle, be written. You just replace the partial derivatives by covariant derivatives. What I don't know if second quatization makes any sense in that case. Probably not.

 

[Arthur Lopes]

In order to understand the SM on a level that is sufficient to actually perform computations you will need:

• Linear algebra
• Multivariable calculus
• Ordinary and partial differential equations
• Transform and series methods
• Group theory
• At least a couple of courses on quantum mechanics
• Special relativity
• Quantum field theory

Note that this is a descriptive list. The points may or may not correspond to actual courses at your university and I might have missed something.

Thanks again! Thanks for the discussion about the use of SM of particle physics in cosmology, really helped me to understand more about the relation about them,

I guess that is not necessary, since (when you use the SM of particle physics in cosmology) the particles interact locally... you don't really see what the interactions between two particles that are separated at cosmo-scales are. Locally everything can be seen pretty flat, as the Earth is flat as long as your communication with your friends (physical) is concerned. It is the same reason why SM of particle physics works on the Earth (which strictly speaking does not have a Minkowski spacetime around it).
For a scalar field in the very early universe (inflaton) I've seen they use GR.

Extra dimensions can be learned with topology and geometry (GR).

Thanks so much for the insight!

They do not, as Orodruin explained in post #2 already.

For the very early universe, both standard models are combined: space is locally flat to a good approximation, so you can study the particle interactions with the particle physics SM while the scale factor of the universe evolves with the cosmology SM.

Thanks!

 

[Carlos L. Janer]

I still don't get it. I don't see how you can calculate how the vacuum energy affects the expansion of the universe based on flat spacetime (a basic assumption of the SM of particle physics).

 

[mfb]

This is purely a GR-question, and in GR you can calculate it. The cosmological constant is a free parameter, you don't have to worry about contributions from particle physics.

 

[Carlos L. Janer]

This is purely a GR-question, and in GR you can calculate it. The cosmological constant is a free parameter, you don't have to worry about contributions from particle physics.

OK, but dark energy MUST be something real. Why not the energy density of the vacuum state?

 

[mfb]

Physics is not about "real".

Why not the energy density of the vacuum state?

Maybe, but we don't understand the interplay of QFT and GR well enough to make a proper prediction based on that - and it would not really help if we have the cosmological constant as additional contribution. There is no reason why it should be zero.

 

[Carlos L. Janer]

Physics is not about "real".

When I write "real" I mean "physical".

Maybe, but we don't understand the interplay of QFT and GR well enough to make a proper prediction based on that - and it would not really help if we have the cosmological constant as additional contribution. There is no reason why it should be zero.

That's precisely what I'm asking. Where can I find textbooks/research papers about QFT in curved spacetimes? Is it an idea worth pursuing, or is it a hopeless attempt? (Linking the cosmological constant to the vacuum state energy density).

 

[mfb]

Where can I find textbooks/research papers about QFT in curved spacetimes?

arXiv, inspire, the usual search engines, ...
QFT in curved spacetimes is interesting, but its applications to our universe are limited to black holes and the very early universe where we have no idea which particles existed at that time.

 

[Carlos L. Janer]

We don't understand the universe we live in: we don't know what dark matter is made of and we don't understand what dark energy is either. But there's a huge difference between these two "dark components": we're currrently making experiments trying to find out what dark matter is. However, we seem to be very happy with the description of dark energy that we have: it's just Einstein's cosmological constant. Is that explanation good enough? I don't think so.

 

[ChrisVer]

Is that explanation good enough?

In the context of GR alone, it's more than enough... I would be skeptical if I saw the universe in GR without a cosmological constant... you can "add" it by hand, and not having it there is weird (something looks special)... what was "special" when Einstein dropped it out? that the Universe was not accelerating (to his knowledge).

 

[Orodruin]

However, we seem to be very happy with the description of dark energy that we have: it's just Einstein's cosmological constant.

What gives you this impression? I do not think this is true in general. There are several attempts at giving dark energy some sort of dynamics, but that does not rule out the possibility of currently fitting cosmological data very well with just a cosmological constant.

 

[Carlos L. Janer]

There are several attempts at giving dark energy some sort of dynamics

I would be very grateful if you could provide me with some references.

 

[Orodruin]

I would be very grateful if you could provide me with some references.

You could start with this review: https://arxiv.org/abs/hep-th/0603057
It is 10 years old, but might still give you a flavour.

 

[Carlos L. Janer]

You could start with this review: https://arxiv.org/abs/hep-th/0603057
It is 10 years old, but might still give you a flavour.

Thank you very much!

 

[ohwilleke]

If you want a conceptual overview of the SM of particle physics beyond what you can find on Wikipedia, I would recommend Richard Feynman's QED, a short text in four single class lecture sized pieces, as an introduction to provide a conceptual framework for everything else afterwords as it puts the concept and conceptual framework in place in a convincing and lucid way.

Episodes 9 and 10 of Carl Sagan's 1980 miniseries "Cosmos", while dated is a good integrative frame to ground you in the basic ideas of cosmology, astrology and its connections to particle physics (although not as deep as the SM of particle physics), before you read something more technical. I believe his book of the same name covers much the same ground.

A lot of trade press and textbook level introductions to cosmology can be found at https://www.amazon.com/s/ref=nb_sb_...ks&field-keywords=cosmology&tag=pfamazon01-20.

A good paper on Lamda CDM that is very up to date is: http://arxiv.org/abs/1605.01533

The Planck legacy - Reinforcing the case for a standard model of cosmology: ΛCDM
Nazzareno Mandolesi, Diego Molinari, Alessandro Gruppuso, Carlo Burigana, Paolo Natoli
(Submitted on 5 May 2016)
We present a brief review of the main results of the Planck 2015 release describing the new calibration of the data, showing the maps delivered in temperature and, for the first time, in polarization, the cosmological parameters and the lensing potential. In addition we present a forecast of the Galactic foregrounds in polarization. Future satellite experiments will have the challenge to remove the foregrounds with great accuracy to be able to measure a tensor-to-scalar ratio of less than 0.01.
Comments: 7 pages, 4 figures. It will appear on the Proceedings of the 17th Lomonosov Conference on Elementary Particle Physics. Moscow State University, Moscow, 20-26 August, 2015. Invited talk

A more critical review that teaches the standard model of cosmology by questioning its premises
and "kicking the tires is: http://arxiv.org/abs/1512.05356

Beyond ΛCDM: Problems, solutions, and the road ahead
Philip Bull, Yashar Akrami, Julian Adamek, Tessa Baker, Emilio Bellini, Jose Beltrán Jiménez, Eloisa Bentivegna, Stefano Camera, Sébastien Clesse,Jonathan H. Davis, Enea Di Dio, Jonas Enander, Alan Heavens, Lavinia Heisenberg, Bin Hu, Claudio Llinares, Roy Maartens, Edvard Mörtsell, Seshadri Nadathur, Johannes Noller, Roman Pasechnik, Marcel S. Pawlowski, Thiago S. Pereira, Miguel Quartin, Angelo Ricciardone, Signe Riemer-Sørensen,Massimiliano Rinaldi, Jeremy Sakstein, Ippocratis D. Saltas, Vincenzo Salzano, Ignacy Sawicki, Adam R. Solomon, Douglas Spolyar, Glenn D. Starkman,Danièle Steer, Ismael Tereno, Licia Verde, Francisco Villaescusa-Navarro, Mikael von Strauss, Hans A. Winther
(Submitted on 16 Dec 2015 (v1), last revised 7 Mar 2016 (this version, v2))
Despite its continued observational successes, there is a persistent (and growing) interest in extending cosmology beyond the standard model, ΛCDM. This is motivated by a range of apparently serious theoretical issues, involving such questions as the cosmological constant problem, the particle nature of dark matter, the validity of general relativity on large scales, the existence of anomalies in the CMB and on small scales, and the predictivity and testability of the inflationary paradigm. In this paper, we summarize the current status of ΛCDM as a physical theory, and review investigations into possible alternatives along a number of different lines, with a particular focus on highlighting the most promising directions. While the fundamental problems are proving reluctant to yield, the study of alternative cosmologies has led to considerable progress, with much more to come if hopes about forthcoming high-precision observations and new theoretical ideas are fulfilled.
Comments: 99 pages, 8 figures. Version published in Physics of the Dark Universe

Another critical view is here: http://arxiv.org/abs/1509.07501

Cosmological Hints of Modified Gravity ?

Eleonora Di Valentino, Alessandro Melchiorri, Joseph Silk
(Submitted on 24 Sep 2015 (v1), last revised 24 Dec 2015 (this version, v2))
The recent measurements of Cosmic Microwave Background temperature and polarization anisotropies made by the Planck satellite have provided impressive confirmation of the ΛCDM cosmological model. However interesting hints of slight deviations from ΛCDM have been found, including a 95% c.l. preference for a "modified gravity" structure formation scenario. In this paper we confirm the preference for a modified gravity scenario from Planck 2015 data, find that modified gravity solves the so-called Alens anomaly in the CMB angular spectrum, and constrains the amplitude of matter density fluctuations to σ8=0.815+0.032−0.048, in better agreement with weak lensing constraints. Moreover, we find a lower value for the reionization optical depth of τ=0.059±0.020 (to be compared with the value of τ=0.079±0.017 obtained in the standard scenario), more consistent with recent optical and UV data. We check the stability of this result by considering possible degeneracies with other parameters, including the neutrino effective number, the running of the spectral index and the amount of primordial helium. The indication for modified gravity is still present at about 95% c.l., and could become more significant if lower values of τ were to be further confirmed by future cosmological and astrophysical data.
Comments: 10 pages, 5 figures. Minor revisions, accepted for publication on PRD

 

[Arthur Lopes]

If you want a conceptual overview of the SM of particle physics beyond what you can find on Wikipedia, I would recommend Richard Feynman's QED, a short text in four single class lecture sized pieces, as an introduction to provide a conceptual framework for everything else afterwords as it puts the concept and conceptual framework in place in a convincing and lucid way.

Episodes 9 and 10 of Carl Sagan's 1980 miniseries "Cosmos", while dated is a good integrative frame to ground you in the basic ideas of cosmology, astrology and its connections to particle physics (although not as deep as the SM of particle physics), before you read something more technical. I believe his book of the same name covers much the same ground.

A lot of trade press and textbook level introductions to cosmology can be found at https://www.amazon.com/s/ref=nb_sb_...ks&field-keywords=cosmology&tag=pfamazon01-20.

A good paper on Lamda CDM that is very up to date is: http://arxiv.org/abs/1605.01533
A more critical review that teaches the standard model of cosmology by questioning its premises
and "kicking the tires is: http://arxiv.org/abs/1512.05356
Another critical view is here: http://arxiv.org/abs/1509.07501

Omg, thank you! you don't even know how helpful you was, that's what I needed!