What is the main challenge of high energy physics?

[dara1998]

TL;DR Summary

What is the main challenge of high energy physics?

Hi, my question is that what is the main challenge of high energy physics? what is the best theory that maybe explain it and why it would not be accepted?

 

[Vanadium 50]

Why do you think there's only one?

 

[mathman]

Main challenge - finding something which cannot be explained by standard model.

 

[mfb]

Main challenge - finding something which cannot be explained by standard model.

Well, that one is easy. Finding a suitable measurement we can do in the lab, on the other hand...

 

[mathman]

Well, that one is easy. Finding a suitable measurement we can do in the lab, on the other hand...

The LHC seems to be the only device which has any hope of finding something. So far nothing beyond Higgs boson.

 

[ChrisVer]

It depends on what you might consider as a challenge.
The main thing is as mentioned to find things that cannot be explained by the Standard Model.
So far, only a few discrepancies have been observed that can be associated with HEP (mainly from B-mesons or the cosmological model), but on their own, they are not determining what might be the cause.
It could be new Physics and that would be nice. However, it could be the case that the SM works fine all the way up to the Planck scale (which is in principle possible).

I think Quantum Gravity is the only thing that we know it must exist but we don't have a theory to explain it. At least the theories that we do suffer from both theoretical (internal) and "scientific" problems. By scientific problems I mean that theories in that regime can't give testable predictions that we can look for in experiments or observations and falsify them. Only a small subset gives such predictions that (so far) have resulted to null outcomes. As a result, they are "not accepted", at least not as physical theories.

 

[mfb]

The LHC seems to be the only device which has any hope of finding something. So far nothing beyond Higgs boson.

Neutron lifetime, proton decay, neutrino masses, muon g-2 and proton radius are open questions where the LHC does not contribute but other experiments are working on it. Most likely the discrepancies will be something mundane and the neutrino masses are the most boring case but we'll see.

 

[vanhees71]

Neutron lifetime, proton decay, neutrino masses, muon g-2 and proton radius are open questions where the LHC does not contribute but other experiments are working on it. Most likely the discrepancies will be something mundane and the neutrino masses are the most boring case but we'll see.

I think the proton-radius puzzle is solved with all the recent high-precision measurements (among them of the group around Haensch). See, e.g.,

https://www.mpq.mpg.de/6365594/11-next-phase-of-the-proton-puzzle

In a way the main challenge is indeed the lack of clear indications, where the Standard Model really fails. One can only hope that the mentioned discrepancies solidify and one finds hints, how to find a more comprehensive model, maybe with new particles who can be taken as "dark matter candidates". Another challenge is also still the lack of a sufficiently large CP violation to explain the matter-antimatter asymmetry in our (observable) Universe.

I, however, disagree with the current criticism of the mathematical methods. There's no other way to express physics than with the sharp language of mathematics, and symmetry principles are still the guiding lines of thought to find new models in accordance with all observations. The success of the Standard Model doesn't disprove this method of heuristics but rather underlines its power. Of course, it's never wrong to look for new methodology, but I pretty much doubt that we'll find by chance the right new idea without a clear phenomenological and quantitative observation to extend the Standard Model to something more comprehensive.