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.
0
votes
0answers
122 views
Neutrino mass with Dirac and Majorana
Why both Dirac mass and Majorana mass terms are needed to explain the mass of a neutrino?
2
votes
2answers
192 views
Fermion Field of Standard Model
Why fermion field is treated as anti-commuting and boson field as truly classical in standard model?
3
votes
1answer
98 views
Weak isospin confinement?
According to the Wikipedia article on color confinement:
The current theory is that confinement is due to the force-carrying gluons having color charge [...],
i.e. because the gauge group is ...
1
vote
3answers
94 views
New physics at high energies, cosmic rays, particle-detectors in space
New physics is expected at high energies and cosmic rays have high energies, so have there been or are there any plans to put particle detectors in space to study cosmic rays for new physics ?
1
vote
1answer
140 views
Symmetry and Conservation
According to Noether's theorem, "Every conservation law corresponds to an underlying symetry or vice-versa" . For example, conservation of linear momentum corresponds to translational symmetry, ...
1
vote
1answer
252 views
Definition of elementary particle [duplicate]
Possible Duplicate:
Why are atoms particles?
According to wikipedia an elementary particle or fundamental particle is a particle not known to have substructure.
Moreover, I've learned ...
2
votes
0answers
93 views
Eternal clocks and 4D spacetime crystals
There was a recent article about the creation of 4D spacetime crystals based on recent theory proposed by Frank Wilczek. This theory is based on breaking time translational symmetry which basically ...
-1
votes
1answer
89 views
Why is the lightness of particles remarkable?
Why is the lightness of particles unexpected?
http://motls.blogspot.com/2012/09/experimenters-susy-frustrations-and.html
1
vote
2answers
288 views
Is the minimum radius of a positronium system of the order of compton wavelength or less than that?
Since from electron-positron annihilation energy and uncertainty principle,the minimum radius of positronium comes out as half of the compton radius.
6
votes
1answer
406 views
Proof of Yang's theorem
Yang's theorem states that a massive spin-1 particle cannot decay into a pair of identical massless spin-1 particles. The proof starts by going to the rest frame of the decaying particle, and relies ...
1
vote
0answers
57 views
Linear rising potential from a Gribov propagator
It is common wisdom that a gluon propagator (Gribov-)like
$$
G(p^2)=\frac{a+bp^2}{cp^4+dp^2+e}
$$
should give rise to a linear rising potential. So far, I have not seen a proof of this and I would ...
1
vote
2answers
249 views
Quark compositions in $\pi^+$ to $\pi^0$ pion decay
Pions can undergo a rare beta-like decay into leptons:
Pion beta decay (with probability of about $10^{−8}$) into a neutral
pion plus an electron and electron antineutrino (or for positive
...
2
votes
1answer
65 views
Explanation for self-rupture glass is needed
I witnessed a phenomenon that I couldn't conclude its cause. Please bear with me for the length of the recall, for I merely want to include any details that might help us to investigate. I had a ...
1
vote
1answer
188 views
What was the first discovery of the delta baryon $\Delta^{++}$?
The delta baryons (also called delta resonances) are a family of subatomic hadron particles which have the symbols $\Delta^{++}$, $\Delta^{+}$, $\Delta^{0}$, and $\Delta^{−}$ and electric charges +2, ...
0
votes
3answers
141 views
Can a single particle create a black hole?
Let us suppose a particle with so much energy $ E= h \frac{c}{\lambda} $ so $ \lambda $ is smaller than Planck's length ?
Would it be possible? I mean if the particle has so much energy then its mass ...
0
votes
1answer
97 views
Electrical Resistance and chemistry
Can some one describe or explain what happens when too much current is passed through lets say a copper wire, I am looking for an explanation to do with physics and chemistry.
For instance we have ...
3
votes
2answers
199 views
Can a neutron be created from pure energy
Is it possible to create a neutron out of pure energy, i.e. not by bringing a bunch of already-existing quarks together? (A quick calculation using E = mc2 shows the energy required would be about 1.5 ...
1
vote
0answers
148 views
Describing the Higgs mechanism to non-particle physicists
I'm sure I'm not the only person with this problem at the moment. I have been asked to give a public (not quite public, scientists, just not physicists) about 'this Higgs boson thing'. I am trying to ...
2
votes
2answers
190 views
Negatve mass inside a black hole
With Hawking radiation, one half of virtual pair falls into horizon and this particle has negative energy.
What would an observer inside horizon observe when seeing negative particles ?
How do these ...
3
votes
1answer
139 views
Why are electric charges allowed to be so light but magnetic monopoles have to be so heavy?
My question is in two parts.
What is the origin of the electric field from an electric charge and why electron can have so small mass? While on the other hand for a magnetic monopole to create a ...
1
vote
1answer
171 views
Do atoms expand with universe? [duplicate]
Possible Duplicate:
Why space expansion affects matter?
Why does space expansion not expand matter?
As we know, the universe is expanding, galaxies are away from each other. But what ...
1
vote
1answer
182 views
What gives matter Gravitational Mass? [duplicate]
Possible Duplicate:
Does the equivalence between inertial and gravitational mass imply anything about the Higgs mechanism?
In Higgs mechanism, Higgs field, which likes syrup, slows down ...
0
votes
0answers
22 views
atomic friction [duplicate]
Possible Duplicate:
Friction between atoms in spring
thanks john:when we apply a stress within elastic range of metal/spring,due to flow of atoms the particular void(defect) region getting ...
1
vote
1answer
95 views
Ratio of the isospin of the photon
as known the photon can have an isospin of 0 and 1.
However, what is the ratio of both for an virtual photon (in e+e- annihilations)?
Next to an 1^-- resonance like J/Psi or Psi' it should be 1 in ...
0
votes
0answers
23 views
Can you recommend me a book on the discoveries and properties of these particles? [duplicate]
Possible Duplicate:
Good book about elementary particles for high school students?
Some days ago, I've found this:
When I was in high-school, They taught me about electrons, protons and ...
2
votes
1answer
351 views
Jarlskog Invariant and its mathematical origin
CP violation is present in the weak interactions if
There are no degeneracies in the up-quark/down-quark matrices
The Jarlskog invariant $J=Im(V_{us} V_{cb} V_{ub}^* V_{cs}^*)$ is nonvanishing
...
1
vote
1answer
99 views
Relating theta_QCD to neutron EDM
How do I relate the topological $\theta_\text{QCD}$ parameter to the electric dipole moment (EDM) of the neutron?
I am very familiar with chiral perturbation theory. I just need to know how to take ...
1
vote
2answers
138 views
Why are atoms particles?
The Oxford English Dictionary definition of particle is as follows:
"A component of the physical world smaller than the atom."
I read an article in NewScientist and it said
"...all particles from ...
3
votes
1answer
116 views
Eq. (5.3.20) Weinberg Volume 1, p. 209
Weinberg claims that it is obvious that the $\sigma = 0$ component of $u^\mu$ at zero spatial momentum points in the 3-direction. This is supposed to follow from (5.3.6). Unfortunately I am not seeing ...
3
votes
1answer
121 views
Do Maxwell equeations change somehow after Higg's boson finding?
When I was in some physics -lesson, probably something to do with Quantum Physics -- the teacher said that certain Maxwell equations would change if the Higg's boson is found. It is also possible that ...
2
votes
1answer
242 views
Hidden particles in higher derivative field theories
Given a higher derivative classical/quantum field theory with say one scalar field, particularly the Lee-Wick standard model. It has been shown that such a field theory encompasses two kinds of ...
2
votes
1answer
229 views
What is a Pseudoscalar particle?
Can someone explain to me what is a pseudoscalar particle?
And how do experiments figure out that what they're dealing with is a scalar or pseudoscalar?
3
votes
0answers
138 views
Spin polarization of decay products
A relativistic moving particle, e.g. muon $\mu^+$, described by its four-momentum vector $p_\mu$, charge $e$ and with a given spin polarization, ${\bf S}=(S_x,S_y,S_z)$, decays into three particles, ...
6
votes
3answers
175 views
supressing certain decay paths and enhancing others with interference
In a scattering reaction, there are many possible final states for the products, each with different production rates.
Question: Is there a way in which we could in general supress certain rates ...
5
votes
3answers
222 views
Higgs Boson: The Big Picture
First, please pardon the ignorance behind this question. I know a fair amount of math but almost no physics.
I'm hoping someone can give me a brief "big picture" explanation of how physicists were ...
0
votes
1answer
92 views
Seeking an account of fundamental particle physics sensitive to the issue of theory-laden observation
The hypothesis of confirmational holism ( http://en.wikipedia.org/wiki/Confirmation_holism ) speaks to all sciences, but seems especially trenchant in fundamental physics, the would-be end of the road ...
4
votes
0answers
150 views
Parity and Helicity of the Higgs Boson
I have been studying how the spin and parity of the new boson discovered at the LHC will be studied and have run into some confusion. The Standard Model Higgs is expected to be a scalar (i.e. have ...
5
votes
5answers
689 views
The observation of a non-SM resonance at 38 MeV
Was reported here. Of course if this is real it is very exciting. It leads me to the question: given that it took so long to find this resonance at a meager 38 MeV, is it possible that all SUSY ...
4
votes
2answers
235 views
Vector Boson Fusion
I have been reading about the production mechanisms for the Higgs at the LHC. It is always mentioned that for Vector Boson Fusion, the initial quarks cause jets that are back to back and with a higher ...
3
votes
3answers
173 views
What is “A” in AGeV?
AGeV means GeV per nucleon. But why A letter is used for such a short cut? Why not NGeV, for example?
2
votes
0answers
146 views
What makes *electric* charge special (wrt. CPT theorem)?
I'm wondering why the 'C' in CPT - charge conjugation - refers specifically to electric charge. Of course you could say that C is just defined as $e^+ \leftrightarrow e^-$... but there has to be ...
3
votes
3answers
236 views
If the electron is point like, then what is the significance of the classical radius of the electron?
What is the physical meaning/significance of the classical radius of the electron if we know from experiments that the electron is point like?
Is there similarly a classical radius of the photon? The ...
3
votes
2answers
157 views
Experimental observation of elementary particles?
I posted a similar yet totally unrelated question recently, and got really satisfying responses to it. Thus, on the same theme...
How have we come to realize the existence of elementary particles in ...
2
votes
1answer
90 views
Parton Distribution Functions plot
I was looking at a plot of the parton distribution functions today and had a question. On the y axis, it seems like the value of x f(x) for gluons is greater than one at small x. I was under the ...
0
votes
1answer
45 views
Bigger anti-matter particles
I have learned about the existence of positrons as a decay product from uranium fission - if I'm not mistaken. Is there any evidence for higher 'mass' anti-matter, or is that mere speculation or ...
3
votes
1answer
175 views
Phase space suppression
In talking about production/decay processes, I've heard people speaking of decay modes or cross sections being 'phase space' suppressed. For example, a two body final state is more likely to occur ...
6
votes
3answers
413 views
How are the masses of unstable elementary particles measured?
I am interested in knowing how (Q1) the particle's masses are experimentally determined from accelerator observations.
What kind of particles? They must be as far as we know elementary and unstable ...
0
votes
0answers
57 views
What is Higgs transition?
In recent publications there is a frequent mentioning of the so-called "Higgs transition" in connection with magnetic monoples. Can anybody please describe the phenomenon in simple terms?
For ...
2
votes
1answer
433 views
What is Dalitz decay?
What is Dalitz decay?
I know there are Dalitz $\pi^0 \to e^+ + e^- + \gamma$ decay, $w \to \pi^0 + e^+ + e^-$ decay, may be more. But is there a rule to say which decay is Dalitz and which is not?
...
0
votes
0answers
37 views
Acceleration/Deceleration Force the ricochet of Energy? [closed]
Could the vibrational force of Acceleration and Deceleration created by quantum particles and cosmic giants, be the vibration that supports string theory? For every +ve there is a -ve, a force is ...
