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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Quantum spin in a rotating reference frame

Rather predictably, I'm having a hard time understanding quantum spin. I know that it has units of angular momentum and relates to rotation, but that it can't be thought of as the actual spin of a ...
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3answers
2k views

Why is the (free) neutron lifetime so long?

A neutron outside the nucleus lives for about 15 minutes and decays mainly through weak decays (beta decay). Many other weakly decaying particles decay with lifetimes between $10^{-10}$ and $10^{-12}$ ...
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208 views

What has been measured at the Higgs experiment and what do we know now?

Explained at the level of a 5$^{\text {th}}$ semester physics student (i.e. pre QFT, but far beyond the level of a news article for non-physicists, which avoids all details and only deals in analogies)...
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1answer
240 views

How to define a field? [duplicate]

Possible Duplicate: What is a field, really? What are electromagnetic fields made of? What is a field ? What is magnetic field or other fields made of or what it is, How do u define it (To ...
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2answers
229 views

From where this number of 14 Tev has arised for proton-proton head on collision in LHC?

I am interested in finding out, why are collisions at 14TeV done in the LHC, instead of some other energy?
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2answers
355 views

Why did Standard Model never sense a requirement to include gravitational quantum? [closed]

Standard Model is advanced (lorentz invariant) version of Quantum physics. It tried to include everything which came in the way while understanding quantum world. It even didn't bother to include ...
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1answer
746 views

Is the Higgs mechanism a fundamental interaction?

Is the Higgs mechanism a fundamental interaction of the same standing as the strong, weak and electromagnetic interactions? If not, is it mediated by the weak interaction? It seems that all the ...
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0answers
98 views

Remaining Potential Experimental Particle Physics Discoveries at the TeV Scale?

With the discovery of the Higgs Boson, some have been calling it the end of experimental particle physics for our generation, due to the fact that all of the particles predicted by the standard model ...
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2answers
2k views

What happens to matter in a standard model with zero Higgs VEV?

Suppose you reset the parameters of the standard model so that the Higgs field average value is zero in the vacuum, what would happen to standard matter? If the fundamental fermions go from a finite ...
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1answer
481 views

How to calculate Rest Mass practically with Standard Model?

With relativistic physics, we can apply force to see resistance against acceleration. It'd give us relativistic mass and we have well established formula to get to the Rest Mass as long as we know the ...
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2answers
871 views

How do you find spin of a particle from experimental data?

So I was wondering, with all this Higgs talk going on, they just detected a particle with a mass of 125 GeV (CMS) or 126.5 GeV (ATLAS). But they still don't know what it is, since there is tons of ...
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1answer
110 views

What good is extraordinary matter to the consumer? [duplicate]

Possible Duplicate: Practical matter of the Higgs-Mechanism This video claims that for everyday matter you only need electrons, upquarks, and downquarks. So are all these other fermions ...
3
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1answer
99 views

Measuring tensor rank of the Higgs resonance

The Higgs boson is the first scalar field ever measured that is fundamental rather than composite. How do high-energy physicists determine that a given resonance in the statistics is either a scalar, ...
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1answer
109 views

The Large Hadron Collider produce material residues?

In the LHC particles are accelerated until they collide, producing energy and this make new particles. My question is what happened after this. What happened to new particles and to old particles ...
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2answers
2k views

What does the discovery of the Higgs Boson mean for physics?

Will this unite some theories, or cause some other change in physics, and perhaps our undertanding of the universe?
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1answer
322 views

What is the winding number of a magnetic monopole, and why is it conserved

I had asked a similar question about a calculation involving the winding number here. But i haven't got a satisfactory response. So, I am rephrasing this question in a slightly different manner. What ...
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1answer
277 views

Why not accurate masses of elementary particles?

In the standard model of particle accuracy in calculating mass is very low. And you can not predict the upper limit of Higgs particle mass accurately. Why not accurate masses of elementary particles?
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3k views

Higgs Boson mass in Electron volts?

Im no physics genius here, I was just interested in the Higgs Boson so I was reading this article : How the Discovery of the Higgs Boson Could Break Physics I came across this Furthermore, ...
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2answers
363 views

How many sigma did the discovery of the W boson have?

When the W boson was discovered in the 1980s, nobody spoke of sigmas. How many sigmas was it at that time?
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2answers
229 views

Batting averages of the Large Hadron Collider

As I understand it, the Large Hadron Collider's function is to throw particles into each other while avoiding hitting the nucleus? If quantum mechanics dictate the position of a particle can only ...
2
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2answers
960 views

Naive question on quantum mechanics and uncertainty principle

This is a follow up on this question, the answer of which points towards Quantum Mechanics. As stated I am not a phycisist so please forgive my ignorance. I will try to understand the issue by going ...
5
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2answers
417 views

Do other particles besides scalars admit tachyonic solutions?

Do other particles besides scalars admit tachyonic solutions? For example fermions or gauge-boson tachyons? The picture in my head is that a tachyonic scalar simply rolls off some unstable potential ...
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2answers
19k views

What would happen after the collision matter and the anti-matter [duplicate]

Possible Duplicate: What actually happens when an anti-matter projectile collides with matter? Suppose 1 kg of a stray meteorite anti-matter moves to the earth. What would happen after the ...
0
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1answer
9k views

Negative and positive energy and Hawking [closed]

I don't have any physics background (except the material we did in high school-long time ago). I was watching a documentary with Stephen Hawking about whether God created the Universe and I could not ...
3
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1answer
254 views

Has the Higgs really been discovered at CERN?

Many news media round the world such as this http://www.scientificamerican.com/article.cfm?id=higgs-lhc have reported the possible discovery of the Higgs at CERN, to be announced at a conference on ...
3
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1answer
1k views

Why is the observed ratio of baryon to photon density considered too small?

Many descriptions about matter-antimatter asymmetry starts with the statement that observed baryon to photon density (about 6.1x10^(-10)) is too small. What is the reason? What ratio is expected?
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58 views

Energy efficiency of antimatter producion [duplicate]

Possible Duplicate: Matter - Antimatter Reactory Practicality Certain reactions in particle accelerators lead to production of antimatter, which can then be collected in noticeable quantities ...
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2answers
356 views

What evidence is there for the electroweak higgs mechanism?

The wikipedia article on the Higgs mechanism states that there is overwhelming evidence for the electroweak higgs mechanism, but doesn't then back this up. What evidence is there?
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2answers
344 views

Scalar potential, vector potential, and spinor potnetial

In Particle Physics, I've seen Scalar potentials which look like this $$ V = a \Phi^2 + b \Phi^4$$ $\Phi$ is scalar (a number). What about vector potentials, and spinor potentials? How are they ...
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1answer
248 views

Straightforward questions about calculating SUSY F-terms

So in the Lagrangian for a SUSY theory we have the F-terms, which I have seen written (e.g., in Stephen Martin's SUSY primer) as $F^*_i F^i$ where $F^i = \frac{\partial W}{\partial \phi^i}$. I ...
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4answers
2k views

Intrinsic structure of electron

The electron contains finite negative charge. The same charges repel each other. What makes electron stable and why does it not burst? Is it a law of nature that the electron charge is the smallest ...
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1answer
149 views

weak bosons and feynman-stueckelberg interpretation

from Wiki "The W bosons have a positive and negative electric charge of 1 elementary charge respectively and are each other's antiparticle." Q:If each is the other's antiparticle then which is ...
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2answers
399 views

How do particle scattering cross sections scale with energy in colliders?

How do particle scattering cross sections scale with energy in colliders? Particularly photons, electrons, protons, and gold or lead nucleii? (If necessary, break this into four separate questions.) ...
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2answers
400 views

How to find an old Soviet physics paper?

I am interested in an old physics paper by Viktor Ambartsumyan and Dmitrii Ivanenko: Doklady Akademii Nauk SSSR, ser. A, No. 6, p.153 (1930). It concerns the structure of the atomic nucleus and ...
2
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1answer
283 views

In a neutron star - what force keeps the neutrons from getting closer and closer? [duplicate]

Possible Duplicate: Why do neutrons repel each other? What I mean is that the neutrons are attracted to one another via gravity, so what force keeps them from collapsing to form a "neutron ...
3
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1answer
366 views

top quark and Z,W bosons?

The masses of the Z and W particle sum almost exactly to the mass of the Top quark,within the errors: Z + W = 80.385±0.015 + 91.1876±0.0021 = 171.57 ±0.0171 GeV Top quark 172.9± 1.5 GeV A: Is this ...
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1answer
395 views

Lepton Number Conservation

What is the global symmetry of the electroweak Lagrangian that gives rise to lepton number conservation? As I understand it, electric charge is some linear combination of the conserved quantities ...
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3answers
627 views

Can every particle be regarded as being a combination of Black holes and White holes?

Can the statement be regarded as true? That every particle, or element in the universe can be regarded as a combination of black hole and white hole in variable proportion.
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1answer
269 views

Is there a tb meson?

I was wandering around the particle date group page for meson and couldn't find a meson for top-bottom, which from symmetry you would expect. Q1: Is this because it hasn't been found? Q2: There is ...
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1answer
878 views

Origin of the Higgs field

Are there any attempts in the literature at addressing the origin of the Higgs field? And, which lines of research that find it inevitable to address this question?
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3answers
2k views

Does the Breit Wigner formula apply to intermediate virtual particles?

Breit Wigner Formula describes the cross section for interactions that proceed dominantly via a intermediate particle (O*) A+B → O* → C + D: $$σ = \frac{2\Pi}{k^{2}}\frac{Γ_{i}Γ_{f}}{(E-E_{o})^{2} + (...
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4answers
506 views

How can there be a quantum field theory that predicts all particle masses?

Say I have a theory with only one (energy) scale, e.g. one given by the fundamental constants $$\epsilon=\sqrt{\dfrac{\hbar c^5}{G}}.$$ In this case, where I can't compare to something else, is ...
7
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1answer
2k views

What is the relationship between string net theory and string / M-theory?

I've just learned from this one of Prof. Wen's answers that there exists a theory called string net theory. Since I've never heard about this before it picks my curiosity, so I`d like to ask some ...
2
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1answer
204 views

Particle mixing and indistinguishability

Neutral kaons have two flavor combinations: $\mathrm{d}\bar{\mathrm{s}}$ and $\mathrm{s}\bar{\mathrm{d}}$. They can also be weak eigenstates: $\mathrm{\frac{d\bar{s} \pm s\bar{d}}{\sqrt{2}}}$. But ...
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1answer
355 views

A comprehensive reference for RF linear accelerator's operation

I'm doing a research on RF linear accelerators (RF Linac), but while studying the material I encountered many problems. I cannot understand the basics of the RF linear accelerators in many ways, for ...
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4answers
2k views

How can/does calculus describe the movement of a particle?

I was talking to Roger Penrose about calculus in the appendix in his book Cycles Of Time and he said I'd need a good understanding of calculus if I wanted to read his book in great depth. He said I ...
0
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0answers
38 views

Two particles interacting by a inverse-square-law force, find their positions in function of time [duplicate]

Possible Duplicate: Two particles are interacting through gravitational forces. How to find their positions in function of time? Given the initial positions and velocities $r_1(0), r_2(0), v_1(...
3
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1answer
2k views

Decay of Cobalt-60 isotope

How does the Gamma decay of Cobalt-60 occur? Motivation: A research team led by D. Habs made contributions to our understanding of the gamma decay of Ca-40 and Zr-90: http://prl.aps.org/abstract/PRL/...
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588 views

Are right handed neutrinos actually antineutrinos and vice versa?

Is it experimentally ruled out that right-handed neutrinos are actually antineutrinos, and left-handed antineutrinos are neutrinos ?
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1answer
306 views

Cloud chamber video showing large particles - What are they?

Watching a video of a cloud chamber on wikipedia (http://en.wikipedia.org/wiki/File:Cloud_chamber.ogg), I cannot help noticing the large collisions that take place at 00:12 and 00:24. What are they?...