
The Higgs boson: the hunt, the discovery, the study and some future perspectives - sohkamyung
https://atlas.cern/updates/atlas-feature/higgs-boson
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saagarjha
> By the end of 2011, ATLAS had collected and analysed 5 fb^-1 of data at a
> centre-of-mass energy of 7 TeV

I'm assuming that the unit being discussed here is inverse femtobarns–but I
don't know what to make of this number. Is high? Low? "Good"?

~~~
tobias2014
A decent perspective comparing to older colliders and an interpretation is
given for example at Wikipedia:
[https://en.wikipedia.org/wiki/Barn_(unit)#Inverse_femtobarn](https://en.wikipedia.org/wiki/Barn_\(unit\)#Inverse_femtobarn)

~~~
scottdupoy
The femtobarn is a unit of area. The inverse femtobarn is basically saying the
number of interactions "per femtobarn". A higher value means more interactions
are occurring.

When you fire a beam of particles at something, or another stream of particles
then you usually want interactions to happen. Some particles miss, some
interact and some are moving too past and fly right by. There is an optimum
energy where the most particle interactions occur. If you plot out the
interaction rates then you usually get a bell curve. This is known as the
excitation function for that interaction.

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BurnGpuBurn
> The significance is typically quoted as σ, or a number of standard
> deviations of the normal distribution. In particle physics, a significance
> of 3σ is referred to as evidence, while 5σ is referred to as an observation,
> corresponding to the probability of a statistical fluctuation from the
> background of less than 1 in a million.

So, no one has ever observed the particle, and the "observation" is in
actuality not an observation. Just a "less than one in a million" chance
fluctuation from the background noise. Which doesn't sound very convincing to
me if you need to run the experiment millions of times to produce the output.

~~~
mnl
So you don't know statistics nor how observations are made in particle
physics... Do you think that we collect these things in a jar and make a
picture? Of course you look for a signal on top of a background, after
modelling it within a control region and then unblinding with data somewhere
else, and of course you compare signal against a Monte Carlo simulation
because there's no other way to do this. You're welcome to suggest 10,000
particle physicists your ideas about how to find particles with lifetimes of
10^-22 s and a production cross section of 57 pb. I don't understand what
makes people that have never opened an actual book about this, nor stepped
into a lab, entitled to think they know better than professionals working
their asses out what they're talking about.

~~~
BurnGpuBurn
Well, one of the problems, for instance, is that experiments like this are
basically un-peer-reviewable. Who has the money to build another LHC? So it's
hard for others to review the work done and thus, basically we all have to
trust ONE team of scientists on this.

But the particle scientists, in this for science and for them rather peculiar
position, don't take proper care at all to explain their findings or their
theories, which is obviously made harder with the absence of pictures from
experiments like we used to have in particle physics. They just anounce "we've
found the Higgs!", throw a party and ask everybody to believe them.

The theories of particle physics are not really understandable unless you
choose to study them very hard for a couple of years, and for sure the amount
of theory needed to understand the experiments at LHC is staggering. I'm just
a layman in this regard, and I will probably never understand the theories you
guys do.

So I'm not a scientist, but I am pretty well versed in politics, and I can
tell you from a political view there's two options: you either found the Higgs
or you didn't. If you did, you'd be very happy and publishing your results. If
you didn't, you'd also be happily publishing results because for all 10,000 of
you it'd be career suicide to admit that y'all just spent 15 billion euros to
build a device that didn't give the expected results.

The amount of anger and disdain displayed by scientists in this field towards
anyone asking genuine questions is starting to look like other fields where
"the science is settled".

~~~
mnl
The thing is you haven't asked anything, you've made your own assumptions and
presented them as facts. There is a single accelerator that provides the
proton beams: the LHC, and there are two independently designed and built huge
main detectors where collisions happen and two independent collaborations, one
for each, that actually make the measurements and then analyze the data of
just theirs. At the LHC there's ATLAS and CMS, they don't share any data nor
staff, and both of them have found the Higgs. Once they publish their results,
they are statistically combined so you have a single value for whatever
property at the PDG. This is how it's done, for obvious scientific-method-
done-right reasons, at CERN at least since 1978 with UA1 and UA2. But you're
not interested in what's really going on, because you're well versed in
politics AKA bullshit, so you can't even grasp that there are competent people
actually doing their job, with stellar standards let me add, and I know
because I've seen a lot of bullshit in action almost everywhere in this fake
it until you make it society we're building so merrily, but not there. You
wouldn't believe it, people actually working? surely they're scamming us
honest maligners, eh?

I left out a relevant factoid. It's almost impossible for a scientist to
become CERN staff, they mostly hire engineers. There are about 25 physicists
at the Theory division and a few more scattered around with a fellowship.
Usually scientists are paid by universities or investigation institutes from
all around the world. Countries pay their contribution to the budget because
it's not a very good idea for your R&D to miss it.

------
ThJ
I too enjoy bosoms. Who's Higgs? Oh! Bos... Never mind.

------
herodotus
Many billions of dollars spent, and no "new physics" seen or even hinted. Now
they have to resort to spin.

~~~
tobias2014
You make it sound like there is money "lost". The dollars that are spent end
up in the economy and go in the development of new materials and technologies
that otherwise wouldn't have been developed. Whether there is a direct benefit
to humanity of finding the fundamental laws of physics is another matter, but
the way towards that has always been very fruitful.

~~~
pasbesoin
E.g., enjoy your life-saving MRI? Thank research physicists.

An often quoted figure, or range of figures, is that the U.S. space program
has, per dollar invested, produced between 5 and 10 dollars of returns in
commercial technology. I don't mean rockets and such. I mean things used in
the everyday world around us.

Oh, and a bit further afield from traditional physics, most of the novel drug
discovery in the U.S. is developed with public dollars, not pharmaceutical
dollars. Pharmaceutical companies convert (some) discoveries to commercial
products, spending more money on later series trials and on marketing, than on
any original research.

And, many drugs were the results of "mistakes". Not what the researchers were
targeting.

You do research to learn novel things. If you already knew what your result
would be, well...

(I could jest, then you'd be a theoretician.)

P.S. Let me also put it this way: You do research also to learn how to learn
those things. Building new equipment, procedures, and understanding. And a lot
of those pay off repeatedly, regardless of the particular result of the
original research topic.

