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.
7
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1answer
314 views
Decay of SUSY particles
In discussion of LHC searches for SUSY particles, physicists seem to assume they will decay quickly to the lightest SUSY particle which then remains stable (at least within the time it takes to leave ...
3
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3answers
368 views
Size of atoms based on atomic number
I'm interested in the size of atoms (extent of the outermost electron cloud), in particular its cross-sectional area and how it scales by increasing Z. (I trust that this won't be affected much by ...
7
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3answers
843 views
Does a particle annihilate only with its antiparticle? If yes, why?
Or to put the question another way - what is the result of a proton-positron collision, or an up quark-charm antiquark collision, etc.? As far as I know, annihilation happens only between particles of ...
7
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8answers
1k views
What future technologies does particle physics and string theory promise? [closed]
What practical application can we expect from particle physics a century or two from now? What use can we make of quark-gluon plasmas or strange quarks? How can we harness W- and Z-bosons or the Higgs ...
4
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3answers
951 views
What is the difference between a neutron and hydrogen?
Differences? They are both an electron and a proton, since the neutron decays to a proton and an electron, what's the difference between a neutron and proton + electron? so is it just a higher binding ...
4
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1answer
1k views
Difference between Higgs and anti-Higgs Fields
I'm assuming the LHC can create a Higgs and an anti-Higgs boson. If so, would their fields be identical with respect to mass effects? How would LHC detectors distinguish between the two bosons?
6
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3answers
257 views
References on the non-compositeness of the known elementary particles
What paper(s) or theory(s) describe or prove that the elementary particles that we have determined today cannot be made up of smaller more fundamental particles?
4
votes
3answers
351 views
Young's experiment or why the light can't be described as a particle [closed]
Who hasn't heard about the double-slit experiment? It figures in any book of quantum physics. But there is something no one can explain to me : I understand why the light cannot be described only as a ...
4
votes
2answers
199 views
CPT violation and how could quark masses differ from anti-quark masses?
A recent experimental paper measures a difference between the top quark and anti-top quark masses:
Fermilab-Pub-11-062-E, CDF Collaboration, Measurement of the mass difference between $t$ and ...
4
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2answers
794 views
Rigid body dynamics joints
I can't seem to find any info on connected rigid bodies by a joint. Can someone explain the basics to me? I'm trying to do a little research to find out how feasible it would be to implement 3d ...
7
votes
3answers
603 views
What actually happens when an anti-matter projectile collides with matter?
I'm trying to understand what would really happen when large quantities (e.g., 10g) of anti-matter collide with matter. The normal response is that they'd annihilate each other and generate an ...
5
votes
3answers
584 views
Kinetic Energy vs. Potential energy with regards to creating particles
So I know that when you collide particles with high enough kinetic energy, (kinetic energy = at least the rest mass of the particles you are making), you get particles.
How come potential energy ...
1
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1answer
145 views
Are there notable cases of anomalies in the mass-decay rate relationship?
As a general rule of thumb, massive particles (both composite and fundamental) tend to decay rapidly through the weak force, while less massive particles tend to be more stable. Hence, taus are ...
1
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2answers
203 views
Mechanical momentum of the EM field in a continuum?
Given an uncharged continuum the EM field produces no force on it. Yet in a discrete system we know that atoms are not uncharged locally and momentum can be exchanged due to the electric field(Which ...
6
votes
5answers
426 views
What Would be the Experimental Signature of Composite Leptons?
So far, the quarks and leptons appear to be fundamental particles. But they're complicated enough that there's always been some speculation that they might be composite.
What experimental evidence ...
3
votes
2answers
501 views
What Quark and Anti-quark are electrically neutral Pions made out of?
A positive pion is an up and an anti-down. A negative pion is a down and an anti-up. What's a pion with an electrical charge of 0?
2
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2answers
257 views
Will physic object in a perfect environment last/exist forever?
We know,i.e. wood/steel tables in earth will completely broken or disappear in a very future day.
If we put the table in a perfect/ideal environment (maybe in vacuum), will the disappear/broken still ...
4
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2answers
256 views
What allows the modified Urca process to work at lower density than direct Urca in neutron star cooling?
The dominant method of neutron star cooling is neutrino emission. There are two regimes usually presented, the "direct Urca" and "modified Urca" processes, each of which are sequences of neutron decay ...
7
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2answers
706 views
What if LHC finds SUSY?
Here and on many other forums and blogs people ask the question "What if LHC does not find SUSY?". I would like to ask the opposite. What if it finds it? What would the implications be? Is it going to ...
5
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3answers
1k views
What defines the mass of elementary particle?
The electron is particle.
The mass of electron is $9.10938215(45)\times 10^{−31}\, {\rm kg}$.
But why is the mass exactly what it is?
What in physics defines the mass of elementary particle?
9
votes
4answers
814 views
Is there an accepted analogy/conceptual aid for the Higgs field?
Is there an accepted analogy / conceptual aid for the Higgs field?
In Physics there are many accepted conceptual aids such as
* Schrödinger's cat
* Maxwell's Demon
* I'm sure I'm missing ...
2
votes
2answers
2k views
“The Schwarzschild Proton” paper - Is the science valid?
I'm a layman without a university background in physics / math. Since I don't have a background, reading a paper is more of an effort.
Consequently, when I come across an interesting paper, I can't ...
2
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2answers
136 views
Mathematical Elegance in a Cosmological Theory Considered Necessary?
In general, it seems cosmological theories that encompass more and more of the phenomena of the universe are expected to be more and more mathematically elegant, in conception if not in detail.
Our ...
4
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3answers
364 views
Cosmic ray hazards
The Pierre Auger Observatory site mentions the detection of a 3E20 eV (48 J) cosmic ray whose energy, well above the GZK cutoff, was based on an analysis of its atmospheric shower. This was equivalent ...
3
votes
1answer
170 views
Paramagnetism what about Paraweakism or Parastrongism?
Ok, I was just curious but the electromagnetic force can allow paramagnetism macroscopically in some objects. Can this be done microscopically to the subatomic level? Also, what about other forces ...
6
votes
4answers
352 views
Matter-Antimatter Asymmetry in Experiments?
As I hope is obvious to everyone reading this, the universe contains more matter than antimatter, presumably because of some slight asymmetry in the amounts of the two generated during the Big Bang. ...
4
votes
2answers
479 views
Higgs Boson Mass
The WIKI Higgs boson site has an interesting diagram illustrating likely Higgs mass intervals that experiments (LEP & Tevatron) or indirect measurements have determined with a 95% confidence ...
4
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1answer
243 views
$B\mu$ from $\tan\beta$ and $\mu$
I'm using the SOFTSUSY package to generate the sparticle spectrum at the EW scale. One of the input parameters is the ratio of the up and down-type Higgs vevs commonly known as $\tan\beta$. The $\mu$ ...
12
votes
5answers
763 views
Are elementary particles ultimate fate of black holes?
From the "no hair theorem" we know that black holes have only 3 characteristic external observables, mass, electric charge and angular momentum (except the possible exceptions in the higher ...
1
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1answer
103 views
Current Physical Applications of Elastic Fractals
Are there any known uses of modeling with elastic fractals in current physical applications? (Especially uses concerning with self-similarity)
4
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4answers
412 views
Neutrino versus Anti-neutrino Detection
Is there a that detection method in use that can distinguish between a neutrino from its anti-neutrino?
6
votes
1answer
187 views
Has anyone actually produced any braided anyons (quasi-particles) yet? (quantum computer)
Quasiparticles theoretically can form braids on a 2D surface. The braids apparently are quite stable for reasonably long periods, allowing a superposition state more time before it decoheres through ...
1
vote
1answer
227 views
With estimates of mass constraints on magnetic monopoles, how likely is one to be found by the LHC(MoEDAL)?
Fermilab seems to have ruled out monopoles with mass less than 850 GeV, but I have seen some estimates of the mass thought to be in the order of up to $10^{18}$ GeV, which, of course, would make them ...
4
votes
1answer
114 views
Do $x$ and $Q^2$ associate with particular directions in the infinite momentum frame?
In deep inelastic scattering, you describe a collision using the variables $Q^2 = -q^2$ (probe virtuality) and $x = Q^2/2p\cdot q$ (Bjorken x, parton momentum fraction). Now, I seem to remember ...
3
votes
1answer
401 views
feynman diagram - direction of arrows
http://upload.wikimedia.org/wikipedia/commons/1/1f/Feynmann_Diagram_Gluon_Radiation.svg
Why does the arrow of the positron doesn't show upwards?
4
votes
1answer
728 views
Why does lambda decay violate parity?
When a lambda particle decays into proton and a pion, I am told it does not conserve parity. Why?
6
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3answers
326 views
Has every possible interaction between elementary particles been observed?
There are some interactions that are forbidden by conservation laws, e.g. an electron cannot turn into a positron by conservation of charge and a photon cannot turn into a positron electron pair by ...
3
votes
5answers
688 views
Why do particles move? [closed]
Is all particles moving and forever?
Can the movement of particles be stoped ?
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3answers
681 views
What is physical in the principle of local gauge invariance? [closed]
Modern theories of interactions in particle physics are gauge ones. I know how the gauge fields are introduced in equations ($D = \partial + A$). I just do not see any physical motivation in it. I am ...
1
vote
1answer
564 views
Quantum numbers of the helicity states of the W boson
What are the weak hypercharge and weak isospin quantum numbers of the helicity states of the $W^\pm$ and $Z^0$ bosons?
The W boson is a spin-1 massless particle. Consequently it has three helicity ...
3
votes
1answer
204 views
Why should the mass of leptons to be near of proton and QCD/chiral scales?
The mistery of the mass of the top being in the electroweak scale can be justified by the Higgs mechanism itself; in some sense the top mass is the only "natural" mass, the other masses of fermions ...
10
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0answers
200 views
Is there any way to distinguish experimentally gauge mediation from gravity mediation in an unambiguous way?
There are lots of models of gravity mediated SUSY breaking with various spectra as well as various general gauge mediation models. Are there any "smoking gun" experimental singnatures that could ...
11
votes
4answers
1k views
Are neutrinos Majorana particles?
That is, are they identical to their anti-particles? (Any results of double beta decay experiments?)
1
vote
3answers
453 views
What restricts the value of weak hypercharge from being 5/3?
The quarks and leptons chiral states have hypercharges of $0,\pm 1/3,\pm 2/3, \pm 3/3, \pm 4/3, \pm 6/3$. The value of $\pm 5/3$ is prominently missing. Is there a theoretical principle which picks ...
4
votes
4answers
543 views
Why are neutrino oscillations considered to be “beyond the Standard Model”?
Is this just a historical artifact - that the particle physics community decided at some point to call all of the pre-oscillation physics by the name the "Standard Model"? The reason I ask is because ...
4
votes
2answers
311 views
Will negatively charged strangelets be produced by the LHC?
Witten (and earlier, Bodner) hypothesized that strange matter (up, down, strange quarks) should be more stable than "regular" nuclear matter(The strange matter hypothesis). That is that the typical ...
10
votes
1answer
987 views
What are the alternatives to the Higgs mechanism?
Can someone summarize, with references if possible, all of the alternatives to the simplest model (that requires only a single scalar Higgs field with the Mexican Hat potential) of spontaneous ...
9
votes
2answers
918 views
trying to understand Bose-Einstein Condensate (BEC)
I am a computer scientist interested in network theory. I have come across the Bose-Einstein Condensate (BEC) because of its connections to complex networks. What I know about condensation is the ...
13
votes
4answers
911 views
What is the need for the Higgs mechanism and electroweak unification?
The Higgs mechanism allows massless fields to acquire mass through their coupling to a scalar field. But if the masses cannot be predicted because the couplings have to be fixed, what really is the ...
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votes
1answer
393 views
How does particle physics compare to other fields of physics? [closed]
Okay, so I just read through huge sections of http://gordonwatts.wordpress.com, which I found quite interesting. There are some questions that really came to my mind.
Do a lot of particle physicists ...
