The Higgs Boson: what are the odds?

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The Higgs Boson: what are the odds?

#1  Postby zaybu » Sep 11, 2011 9:16 pm

From: Revealed: The Best Higgs Plots.


"Everything is excluded at 95% confidence in the mass range from 145 GeV to 460 GeV, but there are small excesses over the range from 115 GeV to 145 GeV. A good thing to notice about this plot is that the expected CLs line is below the 95% confidence limit all the way up to 500 GeV. If there were no Higgs boson in that range they would expect to have excluded it, but they haven’t."

There is a bump at 140GeV, but only with 2-sigma significance. Are physicists grasping at straws? And what are the ramifications, should the Higgs boson be ruled out at those energies?

Thoughts.
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Re: The Higgs Boson: what are the odds?

#2  Postby cavarka9 » Sep 11, 2011 10:00 pm

i hear that we will know by December.
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Re: The Higgs Boson: what are the odds?

#3  Postby zaybu » Sep 11, 2011 10:51 pm

And if it's ruled out, what are the ramifications?There are a few higgless theories, but none of them satify renormalization and/or unitarity.
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Re: The Higgs Boson: what are the odds?

#4  Postby eric8476 » Sep 11, 2011 10:59 pm

is a photon matter or energy?
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Re: The Higgs Boson: what are the odds?

#5  Postby mizvekov » Sep 12, 2011 12:45 am

eric8476 wrote:is a photon matter or energy?

It has no mass, but it does have momentum.
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Re: The Higgs Boson: what are the odds?

#6  Postby eric8476 » Sep 12, 2011 12:54 am

is a particle energy?
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Re: The Higgs Boson: what are the odds?

#7  Postby mizvekov » Sep 12, 2011 1:54 am

eric8476 wrote:is a particle energy?

Particles aren't exactly divided as being either energy or mass particles, since all particles have some associated energy.
Some particles however have no mass.
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Re: The Higgs Boson: what are the odds?

#8  Postby eric8476 » Sep 12, 2011 1:58 am

how can something with no mass have energy? how is a particle associating with energy and how can particles be observable if they have no mass?
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Re: The Higgs Boson: what are the odds?

#9  Postby mizvekov » Sep 12, 2011 2:10 am

eric8476 wrote:how can something with no mass have energy? how is a particle associating with energy and how can particles be observable if they have no mass?

Particles with no mass, like the photon, can still interact with ordinary matter, changing their velocity, because they have momentum.
So in simple words, a photon colliding with an atom at rest will make the atom move.
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Re: The Higgs Boson: what are the odds?

#10  Postby eric8476 » Sep 12, 2011 2:13 am

what makes a photon a particle if it is not mass? why isn't it energy? or is that for the next nobel prize?
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Re: The Higgs Boson: what are the odds?

#11  Postby mizvekov » Sep 12, 2011 3:28 am

eric8476 wrote:what makes a photon a particle if it is not mass? why isn't it energy? or is that for the next nobel prize?

A photon does have an associated energy, it just does not have a rest mass.
It follows from relativity that there is a relationship between mass and energy, that they are essentially the same thing.
It's just that when you calculate how much energy a particle has, most particles have a non-zero energy when they are at rest. These include the most significant components of ordinary matter, like protons and electrons.
This energy is really equivalent to what is known as rest mass, or what is simply known as mass in everyday usage, and you can calculate this relationship with the famous e = mc2 formula.
On the other hand, when you do the same calculation for some other particles, like the photon, you are left with no energy when they are at rest.
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Re: The Higgs Boson: what are the odds?

#12  Postby eric8476 » Sep 12, 2011 3:44 am

a photon has no mass when resting and no potential energy when resting. has mass and associated energy while moving? how is the particle moved without potential energy converted into kinetic energy? how do you calculate non resting mass?
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Re: The Higgs Boson: what are the odds?

#13  Postby epepke » Sep 12, 2011 4:02 am

zaybu wrote:There is a bump at 140GeV, but only with 2-sigma significance. Are physicists grasping at straws?


Would you prefer that physicists give up prematurely, before they have compelling evidence one way or another?
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Re: The Higgs Boson: what are the odds?

#14  Postby mizvekov » Sep 12, 2011 4:36 am

eric8476 wrote:a photon has no mass when resting and no potential energy when resting. has mass and associated energy while moving?

Yes, although you should delete 'potential' from there, and just say energy.
eric8476 wrote:
how is the particle moved without potential energy converted into kinetic energy?

Well, you can't really 'move' a photon, it always propagates at the speed of light. But the formula we have for calculating it's energy is E = (hc)/(2πλ), where h is the planck constant, c is the speed of light, and λ is the wavelenght. Now relativity does not posit that the photon is massless, it just seems so as far as any experiment ever conceived to test it.
eric8476 wrote:how do you calculate non resting mass?

That depends, if you mean the increase in resting mass due to motion, you can use "m0(1 - v2/c2)-1/2" where m0 is the mass at rest.
From this, you can calculate that a car with a rest mass of 2000kg gains an additional 2.15x10-8 grams by moving at 80km/h.
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Re: The Higgs Boson: what are the odds?

#15  Postby epepke » Sep 12, 2011 6:26 am

mizvekov wrote:
eric8476 wrote:what makes a photon a particle if it is not mass? why isn't it energy? or is that for the next nobel prize?

A photon does have an associated energy, it just does not have a rest mass.
It follows from relativity that there is a relationship between mass and energy, that they are essentially the same thing.
It's just that when you calculate how much energy a particle has, most particles have a non-zero energy when they are at rest. These include the most significant components of ordinary matter, like protons and electrons.
This energy is really equivalent to what is known as rest mass, or what is simply known as mass in everyday usage, and you can calculate this relationship with the famous e = mc2 formula.
On the other hand, when you do the same calculation for some other particles, like the photon, you are left with no energy when they are at rest.


More to the point: E=mc2 is a simplification at rest for a more complicated formula that relates energy and momentum with rest mass.

A photon has energy and momentum. When you use that formula, the rest mass is zero. This can only happen if the photon always moves at c
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Re: The Higgs Boson: what are the odds?

#16  Postby twistor59 » Sep 12, 2011 6:38 am

eric8476 wrote:what makes a photon a particle if it is not mass? why isn't it energy? or is that for the next nobel prize?


Good question. I'd say it's debatable whether we should really use the term "particle" in connection with photons !
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Re: The Higgs Boson: what are the odds?

#17  Postby zaybu » Sep 12, 2011 9:03 am

epepke wrote:

More to the point: E=mc2 is a simplification at rest for a more complicated formula that relates energy and momentum with rest mass.

A photon has energy and momentum. When you use that formula, the rest mass is zero. This can only happen if the photon always moves at c


Yes, the formula is:

E2 = (pc)2 + m2c4

In the case of a photon, m=0 leaves you with E=pc.



twistor59 wrote:
eric8476 wrote:what makes a photon a particle if it is not mass? why isn't it energy? or is that for the next nobel prize?


Good question. I'd say it's debatable whether we should really use the term "particle" in connection with photons !


Ha, ha, Einstein would disagree -- his explanation of the photoelectric effect went against the thinking of the day since light was thought as waves since Maxwell, and a course in QFT would convince you otherwise. Photons are the "particles" that mediate the electromagnetic force. Without that, you might as well through QED under the bus.


I'm still waiting for what would be the ramifications should the Higgs bosons be ruled out. Any thoughts?
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Re: The Higgs Boson: what are the odds?

#18  Postby cavarka9 » Sep 12, 2011 9:49 am

dont panic about missing higgs for now.
http://www.newscientist.com/article/dn2 ... r-now.html

with so many theorists and so many ideas, it shouldnt matter, the younger generation who have been told to put a seat belt on their imagination are going to be excited though. :)
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Re: The Higgs Boson: what are the odds?

#19  Postby zaybu » Sep 12, 2011 12:00 pm

cavarka9 wrote:dont panic about missing higgs for now.
http://www.newscientist.com/article/dn2 ... r-now.html

with so many theorists and so many ideas, it shouldnt matter, the younger generation who have been told to put a seat belt on their imagination are going to be excited though. :)



I do agree that a higgless universe might be more exciting than having a higgs field permeating all space. However, finding the higgs does matter as its existence or non-existence will decide the future of physics in a most dramatic fashion. The main problem, should the higgs be ruled out, will be: how do we find another theory for the weak interaction that is renormalizable? This would be for physics a throwback to the 1960's, when people like Weinberg, Salam, Gross et al. thought they are had cornered that problem.
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Re: The Higgs Boson: what are the odds?

#20  Postby twistor59 » Sep 13, 2011 8:00 am

zaybu wrote:
epepke wrote:


twistor59 wrote:

Good question. I'd say it's debatable whether we should really use the term "particle" in connection with photons !


Ha, ha, Einstein would disagree -- his explanation of the photoelectric effect went against the thinking of the day since light was thought as waves since Maxwell, and a course in QFT would convince you otherwise. Photons are the "particles" that mediate the electromagnetic force. Without that, you might as well through QED under the bus.


It's the many courses in QFT I've taken which convinces me that this is the case !

I would prefer to refer to photons as "field quanta", and reserve the term "particle" for entities that had position operators. Photons do not have position operators (regardless of what Margaret Hawton may say). In fact I am not alone in having this view. Lamb states:

Photons cannot be localized in any meaningful manner, and they do not behave at all like particles, whether described by a wave function or not.


I wouldn't put it as strongly as Lamb did - they do sometimes behave like particles (Compton scattering), but I don't like attaching the term "particle" to something without a well defined position operator, since it gives a misleading mental picture.
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