Particle physics is the study of the fundamental forces of nature as they are embodied in the interactions of elementary and composite particles at high energies and short time and distance scales.

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Derivation of the effective potential between a quark and an anti-quark

Typically in particle physics books (not in QFT books!) I have often seen this statement that the potential between a heavy quark and its anti-quark can be "empirically" represented as $V(r) = ...
2
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1answer
293 views

How does one pronounce this particle's name?

How would you read the following particles' names in a conversation in English? I am looking for some "proper" way of doing it. Say, imagine you are reading a technical description in a semi-formal ...
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1answer
938 views

Strong Decay and Parity Conservation?

The following decay is possible according to the PDG and according to my notes it is a strong decay: $$\omega(1420) \to \rho^0 + \pi^0$$ The JPC values are: $\omega(1420)$ 1-- $\rho$ ...
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1answer
200 views

Electron shell bombardment

If you bombard an electron shell with a photon below the critical level to promote the electron to a higher state, will the shell absorb nothing and the photon get deflected with the same amount of ...
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4answers
1k views

Advantage of doing research in theoretical high energy over other fields?

I am undecided about the field I want to do my PhD in, in graduate school. I am asking because the applications that I am filling ask me to write the intended field of study. I found the people who ...
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Why does electron-positron annihilation prefer to emit photons?

If gravitons are also massless, and neutrinos nearly so, why aren't pairs of either of them normally expected outcomes of electron-positron annihilations? Are they possible but simply unlikely, or is ...
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0answers
46 views

Why has the ether been disregarded as a valid medium through which light can propagate? [duplicate]

Possible Duplicate: Ether theory acceptance Although the Einstein's theory of relativity seemed to make the concept of an ether obsolete, did it necessarily invalidate it? Are there any ...
2
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1answer
90 views

What un-ionizes an electron after the photo-electric effect?

In an x-ray tube, the atoms in the anode are ionized by incident electrons "knocking" their K-shell electrons out of orbit. Following this, an outer-shell electron decays to fill the vacancy. Now: ...
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2answers
109 views

Nonabelian gauge theories and range of the corresponding force

Do all nonabelian gauge theories produce short range force?
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2answers
183 views

Can the charge of particles spontaneously flip from positive to negative or vice versa?

I'm thinking of matter antimatter annihilation, are there reactions where normal matter converts to antimatter?
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0answers
93 views

Is the stability of the nucleus due to pions or gluons? [duplicate]

Possible Duplicate: Is it pions or gluons that mediate the strong force between nucleons? (I'm currently studying particle physics in my physics classes at high school so simple language ...
8
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1answer
2k views

why is there no ninth gluon?

A teacher of mine told me once that there were no ninth gluon because such a one should be white and interact infinitely far, and no one has been observed. Is there also a theoretical reason?
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1answer
92 views

How are particle simplices associated into complex particles?

Nonfundamental particles are seen as made up of fundamental particles (in whatever specific theory). consider the simple case of 2 simplex particles (subscript 1 and 2) which form a complex particle ...
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267 views

Where to find cross section data for e- + p -> p + e-?

Where to find cross section data for e- + p -> p + e-? PDG's cross section data listing does not include it.
5
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2answers
628 views

Can different species of particles annihilate with other species

Obviously electrons annihilate with positrons, but can a muon annihilate with an positron, or can an anti-taon cancel with a muon? similarly for quarks of different species, e.g. u and anti-strange. ...
2
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0answers
253 views

Does electron go through a forbidden state when annihilate with positron?

Let's consider an electron-positron pair with total spin equal to zero. When it annihilates it can not emit only one photon because it would have zero momentum and nonzero energy. The pair emits two ...
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787 views
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83 views

QCD corrections in W boson production

The book "Collider Physics", by barger and Phillips, deals with hadronic W and Z productions, and includes the $K$ factor which represents QCD corrections. However, when dealing with the hadronic ...
4
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2answers
603 views

Why mass, charge and spin are good labels for elementary particles?

Why mass and charge are good quantities to labels elementary particles? [I know that what qualifies to be a good label must be a quantity that is invariant under some kind of transformation, but why ...
2
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1answer
168 views

Kinetic energy transfer in matter annihilation?

What happens to the kinetic energy of matter when it is annihilated? Is it released in the resultant explosion? In that case shouldn't it be $E=(mc^2 + \frac{1}{2} mv^2)$ ?
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What is $p_T$? (transverse momentum?)

I've been looking at a few papers in experimental physics (from the ATLAS collaboration, for example) and I've often run across phrases such as "high-$p_T$ electron." What exactly is $p_T$? Is it ...
5
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1answer
1k views

What are the advantages of the ILC over the LHC?

USA Today has an article on Japan's interest as the site for the $10 billion future International Linear Collider. This accelerator will utilize electron/positron collisions (like CERN's former LEP ...
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2answers
756 views

What is the symmetry that corresponds to conservation of position?

We know that conserved quantities are associated with certain symmetries. For example conservation of momentum is associated with translational invariance, and conservation of angular momentum is ...
3
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1answer
449 views

The Particle-Antiparticle Problem in Relation to Special Relativity

Prelude: Let’s consider a pair of events $A(t_1,x_1)$ and $B(t_2,x_2)$,having a spacelike separation wrt an inertial frame denoted by K.In the frame K’ moving along the positive x-x’ direction with a ...
6
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796 views

hadron jets from quark-antiquark in colliders

The observation of hadron jets from electron-positron collisions (LEP) is explained (e.g. Wilczek, The Lightness of Being, p 55) as follows- e,p collide and produce a virtual photon. the photon goes ...
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2answers
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How could something have negative mass?

With all the theories on how Neutrinos apparently broke the light barrier, there was one theory someone told me of how neutrinos might have less than zero mass, but she didn't explain how this was ...
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Topics in particle cosmology [duplicate]

Possible Duplicate: Topics in particle cosmology I am interested in learning more about this interdisciplinary approach. 1) What are some of the top questions in particle cosmology (e.g ...
3
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1answer
104 views

Physics in high lepton chemical potential

I consider zero temperature and high lepton number chemical potential $\mu$. This results in a neutrino (or antineutrino, depending on the sign of the potential) "sea" filling a Fermi sphere in ...
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1answer
309 views

If we know the universe is made up of a relativistic ether, why wouldn't gravity just be a pressure gradient of the ether?

According to one of the answers to a previous question ( Can photons be holes in an ether? ), we know a relativistic ether exists. If we are drifting in such a superfluid, why wouldn't gravity simply ...
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0answers
93 views

Topics in particle cosmology [closed]

I am interested in learning more about this interdisciplinary approach. 1) What are some of the top questions in particle cosmology (e.g nature of dark matter, inflationary structure, topological ...
6
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0answers
190 views

Is there precision experimental evidence for Furry's theorem — that only even degree VEVs are non-zero?

Is there precision experimental evidence for or contradicting Furry's theorem -- that only even degree VEVs are non-zero, specifically for the EM field?
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1answer
638 views

Can photons and gluons be holes in an aether?

Consider photons and gluons have 0 mass and 0 charge. In many respects they're already understood as the absence of a particle by mathematical models. Couldn't this be interpreted to mean they ...
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1answer
2k views

What's the isospin of photons?

What's the isospin of photons? Why PDG book says $0, 1(1^{--})$ for its $I(J^{PC})$? What does $0, 1$ mean here? Is it that the isospins aren't determined and can be 0 or 1?
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3answers
523 views

Are proton, antiproton, electron, positron the only observed subatomic particles that can freely exist and don't decay, i.e. are stable?

Are proton, antiproton, electron, positron the only subatomic particles that can freely exist (i.e. I don't want particles that only exist in bound state as constituents such as quarks) and don't ...
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0answers
144 views

Decay Amplitudes Notation

This question is mostly about how to interpret notation used in Particle Physics. I am given that at lowest order the rate of $b\rightarrow s\gamma$ is proportional to $\langle B_p|b^\dagger ...
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What do “local” and “global” mean when talking about standard deviations in experimental particle physics?

I found the following sentence: The excess is most compatible with a SM Higgs hypothesis in the vicinity of 124 GeV and below, but the statistical significance (2.6σ local and 1.9σ global after ...
3
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1answer
376 views

Has CERN recently found evidence for a Z-prime boson?

In the recent Higgs seminar at 73:38 Guido Tonelli the spokesman for CMS, makes a mistake and refers to a Z-prime in a context that would imply that they see them frequently. He swiftly backpedals ...
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Higgs boson and string theory

Assuming Higgs is found at 125 GeV.Is there any direct or indirect consequence on string theory ? Will it be a blow to string theory or models employing string theory ? ...
6
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1answer
328 views

Status of the little hierarchy problem

What is the current thinking on the little hierarchy problem in light of a potential Higgs mass above 120 GeV? A few years ago, at least, I remember various phenomenologists saying that this at least ...
11
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1answer
113 views

Higgs Field - Is its discovery truly “around the corner”?

Rather surprised I haven't seen many questions or discussion regarding the rumored confirmation of the Higgs field. As I understand it, the energies where they saw things were actually quite a bit ...
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3answers
714 views

How scientists estimated that our universe is 4% normal matter, 21% dark matter, and 75% dark energy?

Is there a simple way to understand how scientists estimated/calculated the following percentages?
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6answers
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Does Kaluza-Klein theory successfully unify GR and EM? Why can't it be extended to the Standard Model gauge group?

As a quick disclaimer, I thought this might be a better place to ask than Physics.SE. I already searched there with "kaluza" and "klein" keywords to find an answer, but without luck. As background, ...
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2answers
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What are bootstraps?

I've heard occasional mentions of the term "bootstraps" in connection with the S Matrix. I believe it applies to an old approach that was tried in the 1960s, whereby - well I'm not sure - but it ...
23
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3answers
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How does the Higgs mechanism work?

I'm not a particle physicist, but I did manage to get through the Feynman lectures without getting too lost. Is there a way to explain how the Higgs field works, in a way that people like me might ...
4
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3answers
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What if we could give photons some mass?

I was reading an article and these paragraphs got me wondering... Before I list the replies, here is some background. The Higgs mechanism describes an invisible field that, it is argued, split one ...
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2answers
139 views

Space expansion effect on wavelengths across two points in space

Is the expansion of space taken into consideration when calculating light or any (Radio to Gamma) wave length distance and speed? I know C is a constant, but my concern is if "space expansion" is ...
5
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0answers
104 views

Seeking chiral anomaly EFT example

If an effective field theory has a chiral anomaly it means that chiral symmetry isn't a symmetry of the underlying theory which has been cut off to make the EFT. My question is whether there's a good ...
3
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1answer
287 views

If LHC searches of a Higgs boson won't be a success, what consequences for the theory of electroweak interaction it can bear?

Whether it is necessary to search still for variants of an explanation of spontaneously breaking gauge symmetry, giving masses for a W, Z-bosons? Goldstone bosons are bosons that appear necessarily ...
6
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1answer
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Are there any reasonable attempts at explaining the OPERA result

as there's so many papers on the opera result and it's a struggle flicking through them all combined with my limited knowledge meaning I cannot well differentiate silly nonsensical papers from ones ...
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Superconformal Multiplet Calculus in 6D

A convenient method for dealing with off-shell formulations of supergravity theories is provided by the superconformal multiplet calculus. This calculus was originally constructed for 4d ${\cal N}=2$ ...