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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Do particles ever touch each other during a collision? [duplicate]

Do particles ever touch each other during a collision? My understanding is that they can get really close to each other but never actually touch, is that true? Another thing I've read about is, the ...
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49 views

What is the 1/2 spin analog of the graviton called?

In some supergravities you have the gravition, gravitino, graviphoton and graviscalar. Each is analogous to each other in only sharing gravitational properties and nothing else. They differ by spin ...
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Preons as scalar-like fermions?

The symmetry of the standard model between the fermions and each generation of them is strongly suggestive of components as proposed in the Rishon model. Having discovered the Higgs boson, we know the ...
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4answers
258 views

Is it possible to split baryons and extract useable energy out of it?

Since baryons (e.g. protons, neutrons) are composite particles it should be possible to split them apart. If so, is it then possible to extract useable energy out of the splitting of baryons in ...
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51 views

Can the technology behind Particle accelerators can be used for energy storage?

As I understand, the kinetic energy of the proton beam in a hadron collider is quite large. Can you build a energy storage system that is based on accelerating a proton beam to relativistic speeds to ...
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100 views

Evidences against Supersymmetry [closed]

Recently, some experiments show that the supersymmetry is not realised by Nature according to the simple models that we currently have. Nevertheless, it is far from saying that the "game is over" as ...
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57 views

Born rule and Feynman propagators

Let us assume that we want to describe the full process of photon emission by electron A and absorption by electron B. Therefore electron B must be on the forward lightcone of electron A. In the ...
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56 views

Does double slit in a vacuum have any effect?

If you do the double slit experiment in a foggy or smokey room, it seems like your going to smudge out the interference pattern, right? Continuing in the other direction it seems intuitive that a ...
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101 views

Why are the Z boson and photon different?

If I understand right the Z boson and photon are both a mix of the same two bosons, the W_3 and the B boson of weak isospin. If the Z boson and photon are both made of the same bosons, then they ...
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47 views

How can W+ boson turn an electron to a electron neutrino?

If you look at the Feynmann Diagram of an electron capture: Whe W+ boson turns the electron into a neutrino. How is this possible? I thought the the boson carries the positive charge and converts ...
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82 views

Elementary particles

That's what Wikipedia says about Elementary Particle: In particle physics, an elementary particle or fundamental particle is a particle whose substructure is unknown, thus it is not known to be ...
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27 views

References on the LHC experiments

I'm looking for a references / short book which discusses what is going on LHC collider - specific experiments, collision processes, analysis of data, how exactly the facility is operating (not ...
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2answers
107 views

Moving Between Degenerate Vacua?

In spontaneous symmetry breaking, moving round the circular valley of Mexican hat potential doesn’t cost energy. These angular excitations are called Goldstone bosons. But doesn't the angular ...
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95 views

What would happen if an incredibly high energy photon passed through a human body?

What would happen if an incredibly high energy photon passed through a human body (or any other material)? When I say incredibly high energy photon, I mean higher than any known energy scales... ...
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120 views

Most particles that have ever been modeled

Two billiard balls collide. Consider the two balls only, how many particles are in that system? Have particle systems of that size been modeled with each individual particle before? What is the ...
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43 views

What are the ways of finding the spin of a particle [duplicate]

How many ways are there for this mission? Any article about that on the internet. I heard about TODAI made a reprogrammable quantum computer. Any more ideas are welcome
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1answer
42 views

Would gravitons follow the same trajectory as photons through a gravitational lense?

Would gravitons follow the same trajectory as photons through a gravitational lense? would all other particles follow the same trajectory?
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59 views

Generalized Unitarity cut of Scalar One-loop Box integral

How does one perform the integrals in four particle cuts in generalized unitarity? It would be helpful how one finds solutions to the simplest case, the fully determined box integral given by: ...
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103 views

Catching/harvesting neutrons

This question has several parts. How does modern science catch free neutrons that are just floating around? Is there anyway to "pull" a neutron off any atom that does not involve our current ...
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2answers
88 views

Can we make usable energy from subnuclear particles?

I understand mass and energy are the same, but in this question I will be talking about mass being turned into usable energy (electricity/heat/etc). We can make our energy through chemical reactions ...
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0answers
64 views

gravitational field as a spin 2 particle using gauge invariance [closed]

can someone help me prove that a gravitational field corresponds to a spin 2 particle using gauge invariance. i know about the tensor formulation of GTR and the gauge invariance in electrodynamics ...
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49 views

Are mesons color polarized?

The binding of quarks in mesons baffles me. It's an Occam's Razor thing. Since a meson is a colorless, the simplest way to bind its two quarks together is to use a $U(1)$ Cartan subalgebra of ...
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57 views

Lorentz force helix

I have a few questions about the Lorentz force. Is it possible to create a Lorentz force helix in a cloud chamber and if so how would this be achieved? How would the pressure inside the helix be ...
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1answer
139 views

CP violation from the Electroweak SU(2)$_{weak,flavor}$ by $\int \theta F \wedge F $

Question: Why there is NO Charge-Parity (CP) violation from a potential Theta term in the electroweak SU(2)$_{weak,flavor}$ sector by $\theta_{electroweak} \int F \wedge F$? (ps. an explicit ...
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155 views

Photons traveling backwards in time?

Imagine that two widely separated charged particles $A$ and $B$ exchange a photon. Because they are far apart one can imagine that there is a major contribution to the photon propagator that travels ...
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215 views

Virtual Higgs boson?

Can particles emit a virtual Higgs boson in a similar manner to the way a virtual photon is emitted?
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63 views

Relativistic Black Hole? [duplicate]

So recently, looking at high energy particles through the lens of General and Special Relativity has peaked my interest. One thing I was considering, using the electron as the first example, is as ...
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1answer
79 views

Two particles state of a 1D massive scalar field

Perfectly localized states are not normalized so do not belong to the Fock space (they belong to the rigged version). Suppose we approximate localized states with gaussians, what is the mathematical ...
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101 views

Photon propagator in terms of creation/annihilation?

As far as I understand it the photon propagator, $P(A\rightarrow B)$, described in Feynman's QED book, gives the amplitude that a photon moves from spacetime point A to spacetime point B. I was ...
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48 views

String Theory- Are strings the end? What are they made of? [duplicate]

Although I have informed myself in string theory through reading books and watching videos, I do not know or understand what superstrings are made of. History has definitely shown us that when we ...
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71 views

How is a Higgs boson created?

I have read a lot on Higgs bosons, yet I do not fully comprehend how they are created and how they are "flicked off" the Higgs field. I have also had trouble comprehending why a Higgs boson quickly ...
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1answer
199 views

Does string theory pose a photon mass problem?

A few weeks ago, I started reading books on string theory. One thing that really seemed confusing or contradictory was that string theory explains that the energy of a superstring gives mass to the ...
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1answer
93 views

How can one calculate the gamma-ray energy spectrum for proton-proton collisions?

How does one calculate the the energy spectrum of gamma-rays produced by a proton-proton collision? I'm at a complete loss.
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1answer
92 views

what determines the direction of a single photon

Photon has momentum and energy.assume i am creating a nuclear fusion by fusing hydrogen nuclei into helium and a photon is created.Now which direction does it(single photon) moves or travel?can we ...
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1answer
64 views

Gravitational interactions by energy?

The mass-energy equivalence, first established by Einstein is an important and highly discussed phenomenon in physics. Without claiming much knowledge about high-end discussions on this topic, I would ...
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30 views

Likelyhood of the creation of a single unbound quark in the collision of very high energy particle beams

I am going over old exam and am not understanding the logic behind the answer given in the mark-scheme. A beam of protons and antiprotons attain energies of 1400 GeV in a synchrotron. Why is it that, ...
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149 views

Electron energy from muon decay

When a muon decays from rest, typically what fraction of the energy is carried off by the electron? I tried looking into some papers, but I wasn't sure how to interpret the graphs they displayed.
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276 views

Angular momentum conservation in pion decay?

I have seen the charged pion decay $$\pi^{-}~\to~ \bar{\nu}_{\ell} +\ell^{-}$$ represented with diagrams containing a $W^-$ in the $s$-channel. The $\pi^-$ and $W^-$ have angular momentum $0$ and $1$ ...
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1answer
78 views

Centrality and collision parameter b

Can someone tell me what does it 20-30% collision centrality mean in terms of impact parameter b?
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1answer
37 views

Lifetime of Positron and its existence

Since we know in condensed matter the lifetime of positron is about 10^-10 seconds, how do we collide positrons with electrons? How many positrons were there during the LEP experiment? I know ...
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1answer
53 views

Is a track in a cloud chamber made by one particle or many particles?

Is the track in a cloud chamber made by one particle interacting with many particles each emiting a photon or is the track made by many particles interacting on the same trajectory? or is it a cascade ...
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2answers
152 views

Charge to mass ratio inversely proportional to curved path radius?

In a cloud or bubble chamber, charged particles follow circular paths. I learned that charge to mass ratio of the particles is inversely proportional to the radius of the path. Thus, a particle ...
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79 views

Textbook about the handiwork of a HEP analysis?

I'm wondering if there is a textbook that describes the handiwork of a particle physics analysis. There are a bunch of books about theory, about the experimental aspects like detectors, and about ...
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1answer
49 views

Free HEP dataset for teaching and demo purposes?

I'm wondering if there are any free particle physics datasets out there, for use in teaching, demonstrations, developing analysis techniques etc.. I'm looking for data events e.g. as ROOT trees or in ...
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1answer
40 views

cloud chamber and bubble chamber

This is a description on cloud chamber and bubble chamber in my book: "energetic charged particles cause ionization in any material they pass through.In cloud or bubble chamber, the ionized molecules ...
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169 views

Can the weak force create a bound state?

My understanding is that the exchange of Z bosons could yield an attractive or repulsive "force" between two fermions. For most combinations the electromagnetic or strong interactions will take place. ...
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2answers
95 views

What is the experimental status of the G2-MSSM?

The G2-MSSM is supposed to be the low-energy theory of a hypothetical class of M-theory compactifications studied by some phenomenologists. It is just the MSSM, but in a particular region of parameter ...
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1answer
71 views

LEP vs. LHC for Higgs production?

Now that we know the mass of the Higgs boson, which system would be better for the production of Higgs bosons, the LEP ramped up or the LHC?
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67 views

Asteroid collision debris calculation

I wonder how to determine the directions, in which the collision debris is launched when 2 asteroids collide. I am aware of: m1*v1 + m2*v2 = m*v = m3*v3 + m4*v4 + m5*v5 + ... and this works just fine ...
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111 views

Matter Waves Interference

When an EM wave diffracts, I can imagine that its EM field interacts with the charges in a certain obstacle thus inducing a wave behaviour on the charges of the matter that will interact with the EM ...