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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Voltage drop along electron beam

A focused electron beam represents a current and unless the charges (electrons) meet no resistance to their movement there should be a voltage drop along the length of the beam. So, assuming the beam ...
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1answer
35 views

Particle physics books [duplicate]

I am a A-Level student. I have keen interest in physics, especially particle physics. So, I want to know some websites where I can find free books or other study materials to study particle physics as ...
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1answer
60 views

Collision of electron and proton of high energy [closed]

What will happen when proton and electron with high energy like in 100 TeV collide?
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21 views

Good books to read [duplicate]

I still regard myself as a beginner in the field of physics.. And there are a lot of information I should know, I am in my second year physics, and I need to read books which are not hard to ...
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1answer
61 views

Charged particle/cosmic ray track on sunglasses

I left my (polarized) sunglasses on car dashboard .. . Returned, and immediately noticed a strongly lightened, partially dotted streak across entire left lens, cutting diagonally from "northwest" to ...
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1answer
51 views

Couplings of fields in the Standard Model

Could someone please explain what this task implies: Calculate coupling of fields: $\bar{e}_{R}e_{R}Z, HW^{+}W^{-}, W^{+}\bar{c}_{L}d_{L}$? (Exercise refers to the Standard Model Lagrangian). What do ...
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1answer
63 views

Conceptually speaking, why does synchrotron radiation arrise?

First, a bit of background. I'm a chemist who works with synchrotron-based techniques, but I'm focussed on materials analysis rather than synchrotron physics. I'm struggling to work out where ...
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0answers
32 views

How many Cherenkov photons on the track of the electron? [closed]

I have this problem where a neutrino interacting with deuterium decay in 2 protons and 1 electron. This electron will produced Cherenkov photon. The specific energy loss of heavy water is ...
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3answers
53 views

Photocurrent's dependence on frequency [duplicate]

Sounds like a rookie question, this, but could someone please explain to me why doesn't photocurrent increase when we increase the frequency of the incident radiation? I mean, an increase in frequency ...
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1answer
25 views

Relativistic blast waves in medium of non uniform density

The relativistic outflow of a gamma ray burst drives a shock into the circumburst medium. This medium could have a uniform density $n_0$ or a density profile of the form, $n(r) \propto r^{-2}$. For ...
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3answers
123 views

String models of particle physics

What general features of particle physics are derived/replicated by constructing string models of particle models? How do such models address the fixing of free parameters like the masses and the ...
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0answers
46 views

Can a photon be captured in a grid space representation at a fractional Planck position?

Consider a photon, positioned in space in a finite portion of a grid. Any point of the grid is vertically or horizontally aligned, each distanced by a Planck unit. $l_P = 1.616 199(97) × 10−35 m$ ...
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111 views

Feynman diagram; $\pi^0+\pi^0\rightarrow \pi^++\pi^-$

For the reaction below draw three Feynman diagrams, one that proceeds through exchange of a gluon, one through a photon and one exchanging a weak W-Boson. $\pi^0+\pi^0\rightarrow \pi^++\pi^-$ Which ...
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33 views

When is the spin of an electron changing?

An electron can have a half spin up or down. The up spin can become a down spin to lose his weak charge. But when are electrons changing their spin?
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2answers
585 views

How to understand that Higgs does not imply circular reasoning?

From what I understand about Higgs (boson/field) it gives mass to subatomic particles. When it interacts a lot with the fields it gets a great mass (like a top quark) and when it interacts a little it ...
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1answer
29 views

Is the magnetic dipole moment in charged particles the more survivable property than the electric charge?

After asking about Which of the properties of particles are intrinsic properties and why? it was commented "Charge, spin, lepton number, baryon number definitely. Mass maybe." and "is magnetic dipole ...
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137 views

Fractionally charged Quarks

Just wondering what the evidence is for fractionally charged quarks, is it simply enough to say that as we see deep inelastic scattering of electrons (at high energies) off the nucleus of an atom ...
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2answers
77 views

Why is an electron considered a point-particle?

Apparently, an electron has mass not greatly smaller than a proton (roughly 1/20, I read, the rest being just binding energy) its volume should, therefore, not be a lot smaller, and its radius between ...
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1answer
53 views

Open Source Particle Tracing Software

I am fairly new to this forum. I am designing an ionospheric plasma testing environment in a thermal vacuum chamber and to do so I require some form of multi-physics package for simulations .. such as ...
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2answers
41 views

Why is the intensity of an alpha ray constant along a material?

I'm taking a course in radiation physics and I've come across the following problem: A thin beam of alpha particles of intensity $I_0$ and energy $E_0$ impacts in a material. What is the intensity ...
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2answers
98 views

Is there a natural source of Antimatter in this universe?

I was just asking if there is an natural source of Antimatter in this universe capable of creating simple molecules/compounds? So, any good answers?
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0answers
64 views

What would be the research advances if we discover the gravitational waves? [closed]

As researchers of LIGO (USA) and VIRGO (France/Italy) say that they have discovered gravitational waves thanks to black hole collision today, what would be, apart of the important confirmation of ...
5
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1answer
73 views

Importance of CP violation

To explain the matter-antimatter assymmetry, CP should be violated according to Sakharov conditions. Charge conjugation is required as matter and antimatter have opposite charges but why Parity ...
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1answer
52 views

Is light relative? [duplicate]

I was wondering, if two cars (A and B) are going at different velocities let's say A=90km/h, B=80km/h then if we add the two speeds we get 170km/h meaning they are relative to each other. But if one ...
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2answers
61 views

Is the video “How to Reveal Subatomic Particles at Home”'s explanation of its experiment misleading?

https://www.youtube.com/watch?v=wN_DMMQEhfQ The video asserts that along the path of an electron or muon, a trail of condensation will appear. But from what I understand, if an electron or muon (both ...
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0answers
27 views

How to determine likelihood of baryon decay

If I want to determine the probability of $\Sigma(1385)^+ \to \Lambda^0 + \pi^+$ how would i do this? I know I have to do something with the $J^P$ value of each part of the decay, but I'm not sure ...
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24 views

Decay of lepton into meson and neutrino using four-momentum

I'm learning about how to use four-momentums and am working through a problem involving the decay of a charged lepton into a charged meson and neutrino. The equation would be: $L^+ \to M^+ + \nu$ ...
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2answers
95 views

Shouldn't atoms of the same element repel each other? [closed]

Shouldn't the same type of atoms repel each other due to electrostatic charge?
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0answers
42 views

Why neutrinos are weakly interacting? [duplicate]

I recently attended a talk on neutrinos, where the speaker said there are billions of neutrinos passes through our body every second, but in our lifetime the probability of alteast one neutrino ...
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2answers
127 views

Do physical entities with one dimension equal to 0 exist?

Within mathematics, a lot of entities with one or more size equal to zero exist and are fluently manipulated. For example, within $\mathbb R^4$, the entity defined as $z=0, t=2$ is a plan, the one ...
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119 views

What physics does the Super Proton Proton Collider intend to explore in the $\lesssim 100\:\mathrm{TeV}$ range?

Chinese scientists have completed an initial conceptual design of a super giant particle collider which will be bigger and more powerful than any particle accelerator on Earth. With a circumference of ...
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34 views

Normalisation of the $\gamma$-matrices

I'm having a little difficulty with understanding the normalisation process of the $\gamma$-matrices. In Thomson Modern Particle Physics 2013, the normalisation of the $\gamma$-matrices are quoted ...
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1answer
41 views

What is the best software to simulate the tracks of muons in matter?

What is the best (free) software to simulate the tracks of muons in matter? I have done some simulations using SRIM/TRIM (www.srim.org) by modifying their proton model to have the mass of a muon, but ...
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1answer
187 views

Where else than Atoms do Photons Disappear and Reappear from? [closed]

Where does photons come from and disappear to? Can photons be destroyed and created? Without atoms would photons exist? What other ways then from atoms can photons be made?
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47 views

What is the physical intuition behind the Bragg peak?

The wikipedia page says: Energy lost by charged particles is inversely proportional to the square of their velocity, which explains the peak occurring just before the particle comes to a ...
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59 views

If there are long-lived elements in the Island of stability, why are they not present in Nature?

To my understanding, some (but not many) physicists speculate that the Island of stability may contain long-lived elements, as in a billion or so years. But couldn't we rule that out just by the ...
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0answers
87 views

What are the preferred subsystems of the universe? [closed]

I am not a physicist but I am interested in philosophical implications of theoretical physics. My understanding is that many physical properties like mass, volume, temperature etc. - are emergent ...
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2answers
112 views

Feynman diagram, which virtual particle?

Hi I have been asked to produce the lowest order Feynman diagram for the following scattering process: $$a.~~~ \mu^-+\mu^-\rightarrow \mu^-+\mu^-$$ $$b.~~~ \mu^-+\mu^+\rightarrow \mu^-+\mu^+$$ The ...
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0answers
30 views

Energy dependency of the total cross section for different species

Comparing the plots for the total (inelastic) cross sections as a function of the centre of mass energy for $pp$ and $e^+e^-$ collisions: one notes that the trend at high energy is opposite: the ...
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1answer
37 views

Does the Higgs Field positive value correlate with “giving mass”?

I understand that the Higgs Field has a positive average value, while the average strength of (almost?) all of the other particle fields is zero. Does that positive value relates specifically to the ...
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0answers
60 views

Effective collision energy at LHC

The proton is not a fundamental particle, so in high energy proton-proton collision we actually collide proton's sub-constituents: quark-quark and (mostly) gluon-gluon. LHC operates now at 13 TeV ...
3
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1answer
90 views

Could there exist (and if not: why?) non-elementary particles composed of gravitons?

I read about glueballs, which should be particles made purely out of gluons. This is a quite theoretical thing but its existence has at least been theorized. Now, I don't know so much about ...
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12 views

Order of the life time of the K± mesons [duplicate]

It is not a homework. I've just wanted to find the order of the life time of the K± mesons. I had some suggestions like Starting from Fermi’s model and dimensional analysis ,Considered decays like K ...
2
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0answers
30 views

Open-source code for computing response functions

Summing Feynman diagrams to compute the response functions of a microscopic model is common in many areas of physics. While conceptually straightforward, the task can be computationally intensive. ...
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1answer
40 views

Showing the annihilation of an electron-positron pair [duplicate]

How to show that the annihilation of an electron-positron pair under emission of one real photon (mass zero) is forbidden by energy-momentum conservation, the emission of two photons is allowed?
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1answer
45 views

Are the leptons in $\beta^-$ decay already present in the nucleus in some form?

In beta minus decay, beta-minus particle and anti-neutrino are ejected, leaving behind daughter nucleus. $\beta^-$ and anti-neutrino both are leptons. Were the leptons already present in the ...
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2answers
772 views

Why couldn't the decay $\pi^- \to e^- + \bar\nu_e$ occur if electrons were massless?

If we assume that electrons (just like neutrinos) are massless, why can’t the decay $\pi^- \rightarrow e^- + \bar{\nu}_e$ occur under the weak interaction?
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78 views

Is muon muon annihilation already realised?

As muon colliders do not yet exist, has muon-muon annihilation already been realized experimentally?
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59 views

Internal energy + energy of electron

Internal energy of a system composed of molecules or atoms is the mean energy of all these particles in the system (energy as kinetic energy, potential energy etc..). But what I am seeing that we are ...
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1answer
65 views

How do we know that elementary particles possess definite parity?

As I was reading Griffiths' "Introduction to Elementary Particles" Wiley 2008, on chapter 4 "Symmetries", the question stroke me. The same as Parity operator (inversion in 3-dimensional space) we ...