Hints Of New Physics At The Lhc?

[jim360]

I'm posting this in news for two reasons:

1. Maximum attention to one of the day's more interesting stories.

2. Just because it has a science bent doesn't mean it didn't pick up interest from multiple sources. Mentioned on Today on Radio 4, for example, as well as articles in the Guardian, Express, Telegraph etc.

I suppose a third reason is that this is more or less exactly related to the areas of physics I specialise in. (Proof: four of the papers cited in this piece of research were co-written by my PhD supervisor.) For those who are interested, I'm offering this as an opportunity to ask a specialist questions about niche physics.

https://www.bbc.co.uk/news/science-environment-56491033

https://www.telegraph.co.uk/science/2021/03/23/key-universe-works-may-have-discovered/

https://www.theguardian.com/science/2021/mar/23/large-hadron-collider-scientists-particle-physics

https://www.express.co.uk/news/science/1413809/cern-discovery-large-hadron-collider-experiment-lhcb-new-physics-standard-model-news-evg

(The Telegraph's headline is overselling things rather, in my opinion, but there we are)

Original paper pre-print, awaiting peer review: https://arxiv.org/pdf/2103.11769

[naomi24]

What for? I would only be repeating myself - and you would be dismissing it - or worse.

[jim360]

What for? I'd be interested to know what makes you think this is a surprise, when in many significant and meaningful ways it is very much not. Even if you have made the general point before, the application to this specific one, and the response, are both likely to be informative in different ways.

[Atheist]

Jim, Naomi. What are you two talking about?

[jim360]

As to the "or worse", all I can say is that this thread is in the News section, not the Science section. Make of that what you will.

[jim360]

Only Naomi can tell you what she's talking about. I don't want to second-guess her any more than I already have, so I'll leave her to speak for herself if she chooses.

[Peter Pedant]

a veritable sybilla

da sybil said things no one cd understand - sortta gobbledegooky but 500 BC - gobbledegookii romani or sumfing ( aut aliquod )

Jim I am sure you wondered if " hooda thunk it?" was directed toward the intellectual effort involved in writing the new paper

congrats if you had a hand in it - or yes you can pull something out of the hat

but this is AB and I think the "hooda fink dat den" may well be a comment on the preceding comments. my knowledge of theoretical physics stopped 1970 when Ph D said - I dont think they will ever get beyond quarks

and the muon 200 times heavier than an electron and carrying one charge. they never told that at skool !

[Peter Pedant]

no dont stop Jim
I wanna put it on record that I read your posts as I always learn something ( in an everyday sense of use darn the supermarket )

to Naomi - OK dont then, but stop whining

[jim360]

Still, the answer to "who'd a thunk?", taken literally, is worth spending time on. The answer is that Physicists did, and have done for some time. The particular measurement reported has already been made before, albeit with less data, by the LHCb already in 2014: http://arxiv.org/abs/1406.6482 , as well as at two other experiments, earlier still: http://arxiv.org/abs/1204.3933 in 2012 and http://arxiv.org/abs/0904.0770 in 2009 respectively. In turn, the measurement was made on the suggestion of other physicists, as far back as 2003 (Hiller and Kruger, https://arxiv.org/pdf/hep-ph/0310219.pdf ). It is worth noting that this first paper made the point of defining this measurement as an ideal test of whether or not New Physics was present: the precise point is that the Standard Model prediction is almost exactly 1, with more or less no uncertainty, and so anything different from that means something new, no matter what it may be.

The precise point then is firstly that physics has been looking at this specific measurement for around two decades now, and secondly that they have been looking at it almost hoping to find something new -- or, at the very least, with the expectation that either something new shows up or it doesn't, and it will be clear one way or the other. It's obviously a pretty narrow focus, but the further point is that it kind of *has* to be. In order to identify the new, you have to be able to clearly distinguish it from what you already know, or think you do; in turn, that also means making sure there is a clear and thorough understanding of what you should "expect" to see.

It's also worth adding that physicists are not desperate to cling to the Standard Model, ie to the current picture, either. It's filled with problems, including a failure to account for dark matter and dark energy, a failure to explain why our universe is matter-dominated, a failure to account for inflation and gravity in general, no explanation for the different masses particles, and so on and so forth. In fact, one of the frustrations of the past decade or so is that all of the hoped-for new stuff hasn't shown up much, if at all. That, however, establishes two very basic truths: our current understanding is incomplete, which we already knew; and our current understanding isn't wrong, because it adequately explains almost everything we have seen so far.

[jim360]

// congrats if you had a hand in it //

I feel I should clarify that I don't have a hand in this particular paper, although I have played a part in the wider discussion related to it: see http://arxiv.org/abs/1506.03970 , sections 5.3 and 5.4 .