All Questions

Filter by
Sorted by
Tagged with
0
votes
3answers
69 views

How do we define “mass” in the context of particle physics and relativity?

In laypersons terminology, mass is defined as the amount of matter. However, consider the following: The $W$ and $Z$ bosons have mass. An antiparticle has the same mass as its corresponding particle. ...
0
votes
2answers
43 views

What is the definition of beam energy in particle physics?

For example, the proton beams in the LHC collider have 7 TeV energy. Does this mean that the individual protons in the beam have 7 TeV energy or that the energy of all the protons in the beam add up ...
1
vote
1answer
24 views

A question on the strong interaction and charm number

I know that the particle $P_c(4380)^+$, has quark content $\bar{c}cuud$. Furthermore I know that the reaction $K^-+P_c(4380)^+\rightarrow K^-+J/\psi+p$, is strong and the quark content on the left ...
3
votes
1answer
38 views

What is $\mathbb{Z}_2$ Parity?

While reading about exotic decays of Higgs boson one of the simplest interaction that we come up with which leads to BSM decays is: $$\Delta L = \frac{\zeta}{2}s^{2}|H|^{2}.$$ This is the ...
9
votes
2answers
2k views

What is the difference between a neutrino and an electron neutrino?

So, what is the difference between a neutrino and an electron neutrino? Like how does the term 'electron' made a difference? Also, what is the difference between an antineutrino and an electron ...
3
votes
1answer
147 views

What is the definition of “force” in quantum field theory?

In quantum field theory, there are certain interactions that we seem to associate with the action of "forces." For example, the exchange of a gauge boson between two matter particles is associated ...
2
votes
1answer
317 views

What is the correct definition of the Jarlskog invariant?

In this lecture on neutrino physics, Prof. Feruglio defines the Jarlskog invariant as $$J=\text{Im}(U_{\alpha i}^{*} U_{\beta i} U_{\alpha j} U_{\beta j}^{*})\tag{1}$$ where $U$ is the neutrino mixing ...
2
votes
1answer
71 views

0-jet and 1-jet categories in experimental particle physics

In experimental particle physics at e.g. the LHC, the analysis of a certain process is often divided into categories described as "0-jet", "1-jet" and "2-jets", etc. Although it seems obvious, I want ...
0
votes
2answers
860 views

What do we mean by differential distribution of some particle decaying into its product particles?

I have come across this term "Differential distribution" in particle physics but have not been able to clearly understand it. Does it mean how the decay observables change with change in some input ...
0
votes
3answers
5k views

What is the definition of an exchange particle?

After reading through articles, i concluded that a suitable definition is that when 2 particles interact bosons are exchanged between the 2 particles creating a force? What would a good definition be ...
3
votes
1answer
610 views

How to tell whether a Feynman diagram is $t$-channel or $s$-channel by looking?

By looking at a diagram, how does one tell whether it represents a $s$-channel process or a $t$-channel process i.e., without finding the amplitude? I'm familiar with Mandelstam variables but I've ...
0
votes
1answer
135 views

Definition of a meson? [closed]

I am looking for a definition of a meson that does not include the quark model. After some research I have come across this definition: A meson is a particle that is (1) believed to be ...
1
vote
0answers
63 views

LHCb Peaking Background

I was reading a paper on the estimation of the branching fraction of B+ to K pi pi gamma. I was wondering whether you could clarify the meaning of peaking background. Thanks!
4
votes
1answer
527 views

Precise definition of jet energy scale and jet energy resolution

Is it correct to say that jet energy scale is only related to Monte Carlo simulations? I can't seem to find a pedagogical introduction about these things that states it properly.
1
vote
1answer
294 views

What is “forward peaking”?

In "Research and Development for a Gadolinium Doped Water Cherenkov Detector" the phrase "forward peaking" is used to describe a signal. This comes up in lots of other contexts too, but I still can't ...
8
votes
2answers
688 views

How come the universe is made of matter and not antimatter?

Antimatter is like matter on opposite day: it has the same properties as the stuff that makes up planets, stars and galaxies, but one vital piece is different—its charge. The universe supposedly ...
40
votes
2answers
1k views

Identification of particles and anti-particles

The identification of an electron as a particle and the positron as an antiparticle is a matter of convention. We see lots of electrons around us so they become the normal particle and the rare and ...
3
votes
1answer
164 views

Neutral current: terminology

In particle physics, where does the term 'neutral current' originate? An example would be an electron exchanging a Z boson with another electron. I understand that the Z boson itself is neutral, but ...
2
votes
2answers
1k 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 ...
4
votes
2answers
469 views

Higgs boson and quasiparticles

Do we know exactly the difference between particles and quasiparticles? Is Higgs boson a particle or a quasiparticle? I ask this because if I understood well, Higgs boson created by a spontaneaous ...
4
votes
1answer
2k views

What is “charge discreteness”?

I assume it is some kind of quantity. Google only made things more confusing. I get that it has something to do with circuits. I also get what a discrete charge is. In fact, I thought charges were,...
12
votes
3answers
3k views

Why are quark types known as flavors?

There are six types of quarks, known as flavors. Why where these types called flavors? Why do the flavors have such odd names (up, down, charm, strange, top, and bottom)?