Has the Higgs Boson Particle Been Discovered at Cern?

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God particle is 'found': Scientists at Cern expected to announce on Wednesday Higgs boson particle has been discovered


Scientists 'will say they are 99.99% certain' the particle has been found
Leading physicists have been invited to event - sparking speculation that Higgs boson particle has been found
'God Particle' gives particles that make up atoms their mass


http://www.dailymail.co.uk/sciencet...iggs-boson-particle-discovered-Wednesday.html
 
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Oh damn. Something is about to go down. Hopefully, they have yet to discover the Higgs. I want to work at ATLAS! :-/
 


there'll be other things to discover; you'll still get to work at ATLAS :)
 


How big a result would finding the Higgs be? It seems like a lot of speculation would have made it a very likely find, just a matter of getting enough data.
 


schaefera said:
How big a result would finding the Higgs be? It seems like a lot of speculation would have made it a very likely find, just a matter of getting enough data.

We will then have gained scientific proof that humans are material beings.
That is something to be celebrated!
:smile:
 


schaefera said:
How big a result would finding the Higgs be? It seems like a lot of speculation would have made it a very likely find, just a matter of getting enough data.

Depending on whose analysis you believe, 125 gig Higgs favors a supersymmetric extension of the standard model over a vanilla standard model. Based masses of top quark, and W boson, standard model would prefer Higgs over 130 gig (according to some).
 


If they have already found it, why should they wait another day to announce that they will find it?

:devil:
 
  • #10


PAllen said:
Depending on whose analysis you believe, 125 gig Higgs favors a supersymmetric extension of the standard model over a vanilla standard model. Based masses of top quark, and W boson, standard model would prefer Higgs over 130 gig (according to some).
I saw a number of 122 GeV/c2 today. I'm not sure of the validity. Lot's of rumors/guesses/speculations on the part of outsiders are flying across the internet.

So let's wait for the announcement later this evening or morning or afternoon in Australia/NZ.
 
  • #11


Transcription of the first few minutes of the video which was temporarily accessible online:

Joe Incandela, the CMS Spokesperson, on CMS progress on the search for the Higgs Boson, 4 July 2012:

We've observed a new particle. We have quite strong evidence that there's something there. Its properties are still going to take us a little bit of time. But we can see that it decays to two photons, for example, which tells us it's a boson, it's a particle with integer spin. And we know its mass is roughly 100 times the mass of the proton. And this is very significant. This is the most massive such particle that exists, if we confirm all of this, which I think we will.

And this is very, very significant. It's something that may, in the end, be one of the biggest observations of any new new phenomena in our field in the last 30 or 40 years, going way back to the discovery of quarks, for example. We see very, very strong evidence of the decay to two photons, and a very very narrow peak in the distribution. We see also the evidence of the decay to two Z-particles, which are like heavy photons, in this particular theory of elementary physics. And then we've studied the number of other channels that have reported, but these are less sensitive and are therefore less conclusive at the moment. But we are very excited. I'm extremely tired at the moment, so I may not appear to be as excited as I really am, but the significance of this observation could be very very great.

It could be ultimately seen that its properties are very consistent with the Standard Model Higgs, or it could be found out that its properties don't exactly match the predictions for the Standard Model.
And if that's the case, then we have something really quite profound here. It could be a gateway, if you like, to the next phase of exploring the deepest fabric of the universe, which is pretty profound when you think about it.

And the other thing I would like to say is that obviously all of this is extremely preliminary. What we've looked for is a few grains on a beach, in one sense. I did some calculations, and if you replaced every event, every collision of the beams that we've scanned or had take place in our experiment over the last two years, if you let each one of those be represented by a grain of sand, you'd have enough sand to fill an Olympic-sized swimming pool. And the number of events that we've collected that we claim represent this observation are on the order of tens, or dozens. So it's an incredibly difficult task, and it takes a lot of care and cross-checking. We're re-calibrating, and we'll have better results, even on the current data, when we release at the end of the month. But it's very exciting.
http://blogs.telegraph.co.uk/news/t...like-the-higgs-boson-has-been-found-probably/

(The bold is mine)

Hans
 
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  • #12


Whats so fascinating about the Higgs particle, is that it is the first example that we know of what seems to be a fundamental elementary scalar in nature.

The only other examples that we know about, are always arranged (by hand) by some experimentalist somewhere (say in condensed matter).

What's really quite astonishing about the whole thing, is that scalar field theory is quite sick theoretically. It's the first thing you learn about in a course on quantum field theory, but in some sense its the theory that we have the least control over, and in many ways has the most mysterious and drastic consequences for physics. Thus, it is also one of the last things you end up studying as well.
 
  • #13


Astronuc said:
... So let's wait for the announcement later this evening or morning or afternoon in Australia/NZ.

There was a thread exactly like this that got locked because the mentors wanted to wait until the actual findings were announced to avoid speculation.
 
  • #14


Here's live coverage of the press conference, it starts in 20 minutes or so: http://webcast.web.cern.ch/webcast/play_higgs.html
 
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  • #15


CMS presented a 4.9sigma-signal using the 3 sensitive channels.

The H->gamma gamma channel is very convincing (with a significance of 4 sigma), here is the summary plot for this channel:

snlw2333.jpg
 
  • #16


Result from the conference:
They observed a new boson with mass of 125.3 ± 0.6 GeV at 4.9\sigma significance.
 
  • #17


Is there any chance this is not the Higgs but something else?
 
  • #18


I do not know of any reasonable alternative, and it fits very well to the expectation of the Standard Model Higgs. It could be something else, but I would not expect anything surprising there.

Edit: Here is the corresponding ATLAS plot, giving (local) 4.5 sigma in the H->gamma gamma channel.

68or2i9m.jpg
 
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  • #19


schaefera said:
How big a result would finding the Higgs be? It seems like a lot of speculation would have made it a very likely find, just a matter of getting enough data.



It's BIG. It's confirming the veracity of the Standard Model, which certain circles doubted because of the hypotethical nature of the Higgs(until now).
 
  • #20


Can someone explain to me how they know this particle is a boson?
 
  • #21


This cannot be verified from the data now, but further studies might study the spin, too, by analysing the angular distributions of the decay products.
Apart from that, theory requires that the Higgs particle is a boson. If it is not, it has to be something else, it cannot be the particles which corresponds to the field responsible for electroweak symmetry breaking.

Edit: Combined significance at ATLAS is 5.0 Sigma.
They quote 126.5 GeV as mass.
 
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  • #22


What are the properties they already analysed that leads them to conclude it is the Higgs? I thought they had the spin 0 already?
 
  • #23


The decay channels H \to \gamma \gamma and H \to Z (\to ll) Z^* (\to ll) with the predicted cross-section*branching fraction and the rough mass, consistent with precision SM experiments with other particles. At the same time, no unexpected excess elsewhere.
 
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  • #24


mfb said:
This cannot be verified from the data now, but further studies might study the spin, too, by analysing the angular distributions of the decay products.
Apart from that, theory requires that the Higgs particle is a boson. If it is not, it has to be something else, it cannot be the particles which corresponds to the field responsible for electroweak symmetry breaking.

Edit: Combined significance at ATLAS is 5.0 Sigma.
They quote 126.5 GeV as mass.

I'm pretty sure I heard someone say that they knew it was a boson, maybe I misheard.
 
  • #26


Do they have really a proof or they are interpreting the result that can be the unexpected signal coming from the mass 126 GeV?
 
  • #27


b/c of the decay channel → 2γ, 2Z° it must be a boson
 
  • #28


Is already anything in arXiv ?
 
  • #29


ammalakinki said:
Do they have really a proof or they are interpreting the result that can be the unexpected signal coming from the mass 126 GeV?

You don't have a proof through experiment. ATLAS and CMS have a 99.9999% certainty that there they have found a new boson with a mass of 125 GeV- consistant with the Higgs. But there are several variants of the higgs.

This is just the beginning: the discovery of a new particle. The future is rich with further discoveries on this new particle.
 
  • #30


In other words, it looks like a duck, and it's where we would expect to find a duck (according to the predictions of QAD = quantum aviodynamics), but we have to do further study to verify that it walks like a duck and quacks like a duck.
 
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  • #31


scalar particle means it is not vectorial.. meaning no directions... does it mean it's non-local? is a higgs value say in a pluto identical to the one on earth?
 
  • #32


In the press conference they talk about determining whether the particle is spin 0 or spin 2, does anyone know why these two particular values for the spin are the discussed candidates? A spin 0 particle would give an isotropic decay guess, how would a spin 2 decay look like, will there be angular dependence (I guess it will) and in that case, how does it look like in detail?
 
  • #33


I don't mean to derail, but what exactly does it mean to have significance level 5 sigma?
 
  • #34


Dickfore said:
I don't mean to derail, but what exactly does it mean to have significance level 5 sigma?

It's a confidence level, level five is 99.99994%
 
  • #35


Dickfore said:
I don't mean to derail, but what exactly does it mean to have significance level 5 sigma?

It's just statistical speak for how accurate the date is more or less. The number of sigma represent the number of standard deviations.
 
  • #36


Sure, but standard deviations of what?
 
  • #37


jtbell said:
In other words, it looks like a duck, and it's where we would expect to find a duck (according to the predictions of QAD = quantum aviodynamics), but we have to do further study to verify that it walks like a duck and quacks like a duck.

Maybe you read too much in Zee's book :-)
 
  • #38


From what little I know about this at present there is a Higgs field which is instrumental in giving particles mass and a Higgs boson which is instrumental in setting up the Higgs field.If this is right then what is instrumental in giving the Higgs boson its mass?:biggrin:
 
  • #39


rodsika said:
scalar particle means it is not vectorial.. meaning no directions... does it mean it's non-local? is a higgs value say in a pluto identical to the one on earth?
Scalar particle means it has spin 0.
 
  • #40


rodsika said:
scalar particle means it is not vectorial.. meaning no directions... does it mean it's non-local? is a higgs value say in a pluto identical to the one on earth?

No, it can vary in space, but it means that it has always the same value at a given point no matter at which angle we look at it.

This is not a case with a photon for example. We could construct an instrument for detecting photons that depend on an angle. I.e. a polarizer. We detect photons when a polarizer is set at some angle and do not detect them when it is rotated by 90 deg. It is impossible to obtain such a polarizer for scalar particles and this is the very definition of a "scalar".
 
  • #41


Dadface said:
From what little I know about this at present there is a Higgs field which is instrumental in giving particles mass and a Higgs boson which is instrumental in setting up the Higgs field.If this is right then what is instrumental in giving the Higgs boson its mass?:biggrin:

That might be why they call it "The God's particle" :smile:
 
  • #42


Dickfore said:
Sure, but standard deviations of what?
Any signal in any experiment could, in principle, be only a statistical fluctuation, an error. Nothing is absolutely certain. The number 99.99994% measures how certain they are that it is NOT an error.
 
  • #43


Demystifier said:
Any signal in any experiment could, in principle, be only a statistical fluctuation, an error. Nothing is absolutely certain. The number 99.99994% measures how certain they are that it is NOT an error.

I also saw the following formulation:
CMS observes an excess of events at a mass of approximately 125 GeV[2] with a statistical significance of five standard deviations (5 sigma)[3] above background expectations. The probability of the background alone fluctuating up by this amount or more is about one in three million.

[2] The electron volt (eV) is a unit of energy. A GeV is 1,000,000,000 eV. In particle physics, where mass and energy are often interchanged, it is common to use eV/c2 as a unit of mass (from E = mc2, where c is the speed of light in vacuum). Even more common is to use a system of natural units with c set to 1 (hence, E = m), and use eV and GeV as units of mass.

[3] The standard deviation describes the spread of a set of measurements around the mean value. It can be used to quantify the level of disagreement of a set of data from a given hypothesis. Physicists express standard deviations in units called “sigma”. The higher the number of sigma, the more incompatible the data are with the hypothesis. Typically, the more unexpected a discovery is, the greater the number of sigma physicists will require to be convinced.

The BBC news article has the following descriptions:
  • Particle physics has an accepted definition for a discovery: a "five-sigma" (or five standard-deviation) level of certainty
  • The number of sigmas measures how unlikely it is to get a certain experimental result as a matter of chance rather than due to a real effect
  • Similarly, tossing a coin and getting a number of heads in a row may just be chance, rather than a sign of a "loaded" coin
  • A "three-sigma" level represents about the same likelihood as tossing eight heads in a row
  • Five sigma, on the other hand, would correspond to tossing more than 20 in a row
    Independent confirmation by other experiments turns five-sigma findings into accepted discoveries

So, I guess, the sigma refers to fluctuation in the background number of events.

But, how did you come up with the number 99.99994% in relation to 5 sigma?! Also, how did the BBC come up with their numbers of 8 heads in a row for 3 sigma, and 20 heads in a row for a 5 sigma?
 
  • #45


Dickfore said:
But, how did you come up with the number 99.99994% in relation to 5 sigma?!

That would be the probability from -5 to 5 in a standard normal distribution. N(0,1)
 
  • #46
  • #47


Dickfore said:
But, isn't the number of background events following a Poisson distribution?

Also, the probability of getting k heads in a row follows the distribution:
<br /> P_k = \frac{1}{2^k}, \ k = 1, 2, \ldots<br />
As different situations have different distributions, "5 standard deviations" is a bit sloppy. The real meaning is "with background only [no higgs], observing so many events is equally unlikely than getting a value >=5 standard deviations away from the mean in a gaussian distribution".


Vorde said:
ATLAS and CMS have a 99.9999% certainty that there they have found a new boson with a mass of 125 GeV- consistant with the Higgs.
No, and this contains a very fundamental error.
You can never measure "the probabilty that you found a particle". You can just give the probability that the measured signal occurs as a random fluctuation (and the probability that this signal occurs if there is a particle).
Simple example: Look for new particles at 1000 different places. Just by chance, you will expect at least one 3sigma-discovery, even if no particle is there at all. Are you 99,7% sure that you discovered a new particle? I hope not.

rodsika said:
scalar particle means it is not vectorial.. meaning no directions... does it mean it's non-local? is a higgs value say in a pluto identical to the one on earth?
Particle properties are assumed to be the same everywhere (and up to now, no variation was found). This is independent of the spin.
A scalar field can depend on spacetime. As a simple example: Temperature is scalar, and it is different on pluto.
 
  • #49


Particle properties are assumed to be the same everywhere (and up to now, no variation was found). This is independent of the spin.
A scalar field can depend on spacetime. As a simple example: Temperature is scalar, and it is different on pluto.

Okie. For a while there. I thought the higgs boson is the carrier of quantum non-locality or connected to it. But then, what's proof it is not connected...
 
  • #50


rodsika said:
Okie. For a while there. I thought the higgs boson is the carrier of quantum non-locality or connected to it. But then, what's proof it is not connected...

No. Since you claim something completely unfamiliar to the rest of us, it is up to you to prove that it is.
 
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