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Particle Physics - The Standard Model
The basic building block of physics



Introduction to the standard model:
We all know the model of an atom known to us from the chemistry class in our school then or now. The electron, proton and neutron will all buzz around in the back of our heads and maybe reactivate one or the other gray cell with which we can associate anything with these names. But what else do we know exactly about these names?

Proton: an electrically positively charged particle in the atomic nucleus
Neutron: an electrically neutrally charged particle in the atomic nucleus
Electron: an electrically negatively charged particle on a path around the atomic nucleus

That was the end of the matter for us and we should not and did not want to know more. Perhaps we were also given the insane number of 6.022 141 79 (30) * 10²³, which means 602 trillion in German. Maybe you still know her by the name 1 Mol ?!
Mol was the amount of substance in a system that consists of as many individual particles as there are atoms in 0.012 kilograms of the nuclide carbon-12 (12c). Such huge numbers are indispensable in today's physics.

And what do we know today about the structure of an atom?

Proton: is a long-lived positively charged hadron (symbol p). It consists of two u-quarks and one d-quark (formula- "uud"  up up down). It is surrounded by a lake of gluons and quark-antiquark pairs. Less than 20% of the mass of the proton comes from the so-called valence quarks. The rest is made up of the gluons that transmit the strong force (strong interaction). The diameter of a proton is just 1.7 * 10-15 m, and the proton is a baryon.

Neutron: is an electrically neutral hadron (symbol n), but still has a weak magnetic moment. It is part of the atomic nucleus like the proton and together they can both be referred to as nucleons. Unless it is bound in an atomic nucleus, the neutron is not stable. The neutron has a ½ spin like the proton and is therefore a fermion. It belongs to the "family" of baryons and consists of two d-quarks and one u-quark (formula- "udd" up down down). In addition, the mean service life extends to 885.7 ± 0.8 seconds.

Electron: is also known under the name Negatron. The electron belongs to the leptons and, like the neutron and proton, has a ½ spin. And since they have a half-integer spin, they automatically belong to the class of fermions. Far away from all others, the electron holds the record for its mean lifespan of 1024 years. In contrast to the fact that the universe is “just” 13.7 ± 0.5 billion years old.

"..."
(Now there is actually a table with properties of the electron / proton / neutron, but since the formatting is lost, I'll leave that out)
"..."

A little introduction to what we didn't have to learn in class. But as you can imagine, that wasn't all the particles. Here's a small starter for “dinner”: photon, gluon, graviton, W and Z boson / Higgs boson / gauge boson,, leptons, quarks, mesons, baryons, tachyons, antiparticles and others.

First of all, about all of the particles. But what exactly is the standard model? What is it made of?

The standard model of elementary particle physics is a physical theory. With the help of mathematical formulas, she describes the elementary particles known to us and their interactions between them. The three interactions known to us so far are the strong interaction, the weak interaction and the electromagnetic interaction. The Standard Model (SM - abbreviated) could also be called a relativistic quantum field theory. Among other things, it is subordinate to the laws of the special theory of relativity. The fundamental objects are fields in spacetime (field theory) that are only changed into certain packages (quantum theory). The predictions of the SM are well supported by many particle physics experiments. However, a few particles are still not affected, which are said by the SM, e.g. Higgs boson, graviton. The SM does not include the 4 basic forces, gravity, and therefore cannot explain certain observations sufficiently. In addition, there are 18 parameters that have to be determined in advance through experiments, regardless of the theory. This makes the SM quite “flexible” and can, within a certain framework, adapt to the observations actually made. Even if this theory only represents the basic building block of modern particle physics, it is still not sufficient overall to explain the world. There are already numerous efforts to expand or replace it.

In the standard model, 12 building blocks of matter are divided into 3 particle families (particle generation). So far there has not yet been a need to assume more than 3 particle families.
They belong to the first family
• electrons
• Neutrinos (originate from nuclear decays and in the sun)
• Up and down quarks
They belong to the second family
• The muon
• The muon neutrino
• The Charm and Strange Quark
And they belong to the third family
• The Tauon
• The tauon neutrino,
• The top and bottom quark
The stable matter surrounding us consists of 4 of these particles - particles of the first family: electrons, electron neutrinos, up quarks and down quarks. The other 8 particles are heavier copies of the first family and can be detected using cosmic rays. However, these are unstable and, as mentioned before, transform into the particles of the first family. The exact reason for their existence remains unclear. According to their properties, these 12 elementary particles are divided into “groups”: quarks and leptons


Leptons:
›The name" Lepton "has Greek roots (leptòs =" light "," small ")
›Leptons are fermions, so as particles with half-integer spin they are subject to the Fermi-Dirac statistics and thus also to the Pauli principle, which has a decisive influence on the occupation of the individual energetic states.
›Leptons are subject to weak interaction. This force is an attractive or repulsive force, but transforms particles into one another. She is under
among other things responsible for the ß- decay, in which a neutron is transformed into a proton, an electron and an electron antineutrino.

›Leptons are elementary particles. Since they do not belong to the quarks, they do not exchange gluons and are not subject to the strong interaction.
›If a lepton carries an electrical charge (muon, tauon, electron) it is subject to electromagnetic interaction.
›Leptons are subject to gravity. However, the electron and electron neutrino have a very small mass, which keeps the gravitational effect within limits. (That is why gravity is often neglected in school lessons)


›Uncharged leptons are the neutrinos. They are very difficult to detect because they hardly interact with other particles of matter. With the cosmic rays we are constantly getting 10 13 neutrinos per cm³ and second. New experiments are based on a small but finite mass of neutrinos.
›The latest findings in this area indicate that neutrinos are not stable, but can transform into one another.

Quarks:
›Murray Gell-Mann and George Zweig (Caltech) postulate the quarks in 1964.
›Like leptons, quarks have a ½ spin and are therefore fermions.
›The 6 types of quark are differentiated by assigning a quark flavor to each: Up, Down, Strange, Charm, Bottom (Beauty), Top (Truth).



›Up-Quark
- Name because of the isospin (quantum number)
- Isospin corresponds to an angular momentum - up or a down + ½
- Mass: because quarks never appear alone, but always in groups, the individual quarks can only be deduced from the mass of the group
›Down quark
- Isospin: - ½
- According to previous knowledge, the down quark is stable
›Strange-Quark (strange)
- Introduced to explain the structure of some baryons like Σ +, Σ-, Σ0
- Negative quantum number strangeness of a particle indicates the number of strange quarks it contains
Strange Matter (Strangelet)
The strange matter consists of the elementary particles that do not occur naturally on our earth and that contain the strange quark. Particles that consist of 3 quarks, such as protons and neutrons, are called baryons. If there is a rod of quark in the particle, it gets the name hyperon. The hyperons are unstable. Mesons, which consist of a quark and an antiquark, can contain the strange quark. Example: the kaon. But there can also be doubly strange particles.
›Charm quark
- Counterpart of the strange quark
- Has the charm quantum number C = 1
- The charm quantum number was introduced in 1974 in order to be able to classify the newly discovered J / Ψ meson in the particle zoo.
- Predicted in 1970, first artificially created in 1974.
- Lifespan is approximately 10-12 seconds
- They can only transform themselves into strand quarks via the "weak interaction"; therefore, compounds with charm quarks have a relatively long lifespan
›Bottom Quark (Beauty)
- First proven in 1977
- Service life approx. 2 • 10-12
›Top Quark (Truth Quark)
- Heaviest curd
- Service life approx. 10-24
- Does not occur in nature

(Addendum, doesn't everything fit in at once: P)


Weak interaction:
It is also called nuclear force in specialist circles and is one of the four basic forces. In contrast to the other basic forces (gravitation, electromagnetism) it only works at very small distances. Distances that just refer to 10-35. Like the other basic forces, it takes care of the exchange of energy and momentum and acts primarily when the particles involved decay or transform.
The fusion of hydrogen to helium in the sun plays a very important role in the weak interaction. This is the only way to convert protons into neutrons. Because of the weakness of the weak interaction, this process is very slow.

Strong interaction:
The strong interaction (also called strong nuclear force) is another of the four basic forces in physics. Due to its property that it becomes stronger with increasing distance, it has paradoxical appearances when viewed from a human perspective. The strong interaction holds, among other things, the quarks and all the particles composed of them such as nucleons (protons and neutrons) together in the atomic nucleus and is therefore also referred to as nuclear force. It can therefore stabilize atomic nuclei against the mutual electrical repulsion of the protons much more than the electromagnetic interaction. All hadrons (baryons and mesons) are subject to the strong interaction.
The strong interaction, like the electromagnetic and weak interaction, is described by the exchange of bosons (exchange particles). In the case of strong interaction, these exchange particles are called gluons, of which there are eight types (different color charge states). The gluons transfer the color charge between the quarks, which means that a gluon can interact with other gluons and exchange color charges.
In the case of the strong interaction, it is very important to distinguish between the interaction of the quarks and the effective interaction of the quarks from composite particles.

Electromagnetic interaction:
The electromagnetic interaction takes place via an exchange particle: the photon g. In addition, all particles with an electrical charge take part. This photon, also called light particle, is electrically neutral itself and has no mass. Therefore, it can travel at the speed of light and travel relatively long distances. This is another reason why we can perceive electromagnetic interactions in everyday life. However, in particle physics only the electromagnetic phenomena are explained by the exchange of photons and not simply by an electromagnetic force.



Formula designation:
C - coulomb
J - joules
MeV - mega electron volts
T - Tesla
c - speed of light
GeV - Giga electron volt (1.60217646 * 10 -10 J)

Swell:
http://de.wikipedia.org/wiki/Mol
http://de.wikipedia.org/wiki/Neutron
http://de.wikipedia.org/wiki/Proton
http://de.wikipedia.org/wiki/Elektron
http://de.wikipedia.org/wiki/Lebensurance_(Physik)
http://de.wikipedia.org/wiki/Compton-Wellenlänge
http://de.wikipedia.org/wiki/Teilchenphysik
http://de.wikipedia.org/wiki/Standardmodell

http://homepages.physik.uni-muenchen.de/~Otmar.Biebel/TeVLHC-seminar/KBehr-Standardmodell.pdf
http://web.physik.rwth-aachen.de/~hebbeker/lectures/sem0304/indenhuck2.pdf
http://www.uni-magdeburg.de/exph/biologie/Standardmodell.pdf
http://www.physik.uni-regensburg.de/didaktik/LFortbildg/MNU/2007/Lenz_Standardmodell.pdf
http://www.physik.uni-mainz.de/F-Praktikum/Das%20Standardmodell%20der%20Teilchenphysik_Walk%2 030.10.06.pdf
http://www.desy.de/~boehmej/teaching/vl_08_bilder.pdf

http://www.biosphaere.info/biosphaere/inhalt.php?artnr=000182&thema=AAWP
http://www.biosphaere.info/biosphaere/inhalt.php?artnr=000183&thema=AAWP
http://www.biosphaere.info/biosphaere/inhalt.php?artnr=000065&thema=AAWP
http://www.biosphaere.info/biosphaere/inhalt.php?artnr=000068&thema=AAWP
http://www.biosphaere.info/biosphaere/inhalt.php?artnr=000181&thema=AAWP
http://www.physicsmasterclasses.org/exercises/bonn1/de/ww_elektromag.htm

Thanks for reading through :-) and suggestions for improvement
mfg Herry

Just a question. In front of which audience will the lecture be given? For the normal school you use tons of terms that have to be explained first. Most of them would only understand the train station and sleep away after 2 minutes. Somehow a common thread is missing.

..
Electron: is also known under the name Negatron. The electron belongs to the leptons and, like the neutron and proton, has a ½ spin. And since they have a half-integer spin, they automatically belong to the class of fermions. Far away from all others, the electron holds the record of the average lifetime of 1024 years. In contrast to the fact that the universe is “just” 13.7 ± 0.5 billion years old.
...


Negatron hasn't been said by anyone for a long time. :)
As far as we know, the electron is stable; you have never seen one disintegrate (into whatever; it is the lightest charged particle and the charge cannot be lost in the event of a disintegration).
The experiments come to the conclusion that the lifetime of the electron is definitely greater than

tau (electron)> 4.6 * 10 ^ 26 years

(i.e. 4.6 times 10 to the power of 26 years) is (and not 1024 years). Now that is really much more than the age of the universe.

However, it still doesn't hold the record (as you say). For theoretical reasons, the proton has been studied in extreme detail in this regard. Some theories predict that it will fall apart. But in all the complex experiments (in gigantic underground water tanks) one has never seen one disintegrate. Therefore there is only one lower bound for the lifetime (as with the electron above):

tau (proton)> 2.1 * 10 ^ 29 years

so the proton looks more like the record holder. :)

Swell:
http://en.wikipedia.org/wiki/Electron
http://en.wikipedia.org/wiki/Proton

Maybe your literature sources are too old?

Uli

Negatron hasn't been said by anyone for a long time. :)
As far as we know, the electron is stable; you have never seen one disintegrate (into whatever; it is the lightest charged particle and the charge cannot be lost in the event of a disintegration).
The experiments come to the conclusion that the lifetime of the electron is definitely greater than

tau (electron)> 4.6 * 10 ^ 26 years

(i.e. 4.6 times 10 to the power of 26 years) is (and not 1024 years). Now that is really much more than the age of the universe.

Should mean 10 ^ 24 years and not 1024 years.

Should mean 10 ^ 24 years and not 1024 years.

How (and by whom) was the service life measured?

Kind regards

Post deleted. Reason: the school physics forum is not about questioning standard physics.

Uli

How (and by whom) was the service life measured?

Kind regards

Sufficient references were given in the contributions.
Please take a look yourself, b.l.ö.d to ask.

How (and by whom) was the service life measured?

Kind regards

Hardly measured directly. The magic word is extrapolated. However, it is a mystery to me how and from what a service life of 4.6 * 10 ^ 26 years could be extrapolated. Does somebody has any idea?

@Lorenzy is not too strict, the terms used by Herry are all correct and well known.

I don't doubt that they are correct. Well known? Hence my question to the thread creator, for which environment this term paper was written.

Hardly measured directly.The magic word is extrapolated. However, it is a mystery to me how and from what a service life of 4.6 * 10 ^ 26 years could be extrapolated. Does somebody has any idea?
...


I think that's statistics. Since you can't wait that long, you take a different approach and take extremely large samples of decay candidates and wait for a decay - hence the huge water tanks in the proton lifetime experiments. For the electron, too, the size of the statistical sample should be decisive.

Uli

I think that's statistics. Since you can't wait that long, you take a different approach and take extremely large samples of decay candidates and wait for a decay - hence the huge water tanks in the proton lifetime experiments. In the case of the electron, too, the size of the statistical sample is likely to be decisive.

Uli

It is clear to me that these are pure statistics. But how can you infer a minimum lifespan if decay has never been observed? The number of 4.6 * 10 ^ 26 years must have been calculated from some observation.: Confused:

Hello,

Just a question. In front of which audience will the lecture be given? For the normal school you use tons of terms that have to be explained first. Most of them would only understand the train station and sleep away after 2 minutes. Somehow a common thread is missing.

I do think that this is school physics. Everyone should already know this.

greeting

Sebastian

Does it mean the forum rules below are invalid?
Cripti, these are not the rules, and it says 'physics cracks', not 'physics cranks'. You still have homework to do, including learning the basics about coordinate transformations.

But how can you infer a minimum lifespan if decay has never been observed?
Very simple: When you do experiments in which you should have observed a decay, but you don't. A probable minimum service life can be extrapolated from this.

Kind regards

Very simple: When you do experiments in which you should have observed a decay, but you don't. A probable minimum service life can be extrapolated from this.

OK. Makes sense.

Hello Lorenzy,

it works, roughly speaking, like this:
One takes a correspondingly large (known) number of protons.
Now one waits (years) for events that could be proton decay.
If one has now waited a certain time with a certain number of protons and no clear event has been registered,
the minimum lifetime of the protons can be calculated from this.
Coarse: if none of 4.6 * 10 ^ 26 protons has decayed in one year, then the lifespan of a proton is at least 4.6 * 10 ^ 26 years.

Lifetime τ = (No-dN) * dt / dN, at dN = 0 stop "at least"


Greetings EMI

Okey dokey. Thanks for the more detailed explanation.

First of all, thank you for the helpful answers! : D
I'll get down to work right away and revise the housework.
It was vaguely clear to me that there is still no visible thread to be seen. That's why I'm trying to get one in!

Did I forget to mention something? Somebody is missing something in particular? : D

I also noticed that some terms might be unclear and wanted to add a "short appendix with explanation" to the term paper anyway.

The housework is mainly for my physics teacher, I only have to convert it later into a lecture for my class (13th grade).

Will the revision then via txt. Attach document :)

That’s coming very late Kurt. New Years Eve 1999/2000 the world should end!


I know that they asked me to confirm that my built-in clocks (32Khz circuits) did not lead to a system crash.
Well, they were only there for the printer, so what could that do?


Surely you noticed it yourself a long time ago that your comment was absolutely superfluous, something superfluous and useless!


It is absolutely not superfluous.
Remember: you have quoted a method that has not been tested and cannot be tested either.
I was much more certain about my watch.
After all, no more than one wrong -date- could be written.
But you presuppose that all the circumstances concerning the stability of the proton are - eternally - like in this one year.
But that shouldn't be the case.
(and you didn't consider the champagne either)


You should keep it real, real! once again for thunderstorm!


Caution, don't jump off, you will go wrong at some point :)

Kurt

@herry
You have to say what the aim of this work should be / what message do you want to get across?
Right now your structure is something like this:
-Remember atomic model
- There are many more particles - and they are all listed
-There is the standard model
-Brief explanation of the basic forces / interactions

It is absolutely superfluous to enumerate all the properties of all possible elementary particles, nobody cares and nobody in school will be able to do anything with them if you tell them something about isospin conservation and flavor or strand quantum numbers.

I'm not exactly sure what your assignment was.
Somewhere it was about the atomic structure, right?
The standard model is actually a number too far - I would first want to start with quantum mechanics.

If it is supposed to be the standard model, you should try to motivate the model a little.
In a nutshell:
In the beginning there was the Schrödinger equation. But already Schrödinger discovered that it is not compatible with the spec. Rel.Th. is, so he came up with something new - the equation now called the Klein-Gordon equation. But it causes stress because it has negative probability densities. So a man named Dirac set up a new equation that doesn't have these problems, but posits negative energies instead. That's bad, but Dirac knows what to do. Of course he knows the Pauli principle of exclusion (never two fermions in the same state) and says that the negative energy levels are all occupied. Electrons with negative energy can be brought "up" and then a hole is created in the "Fermi lake". That was the theoretical hour of birth of the positron - the first antiparticle that was recognized as such and also discovered a few years later.
Particle physics achieved the next breakthrough with quantum field theory, which made it possible to quantize the Maxwell fields and explains the photons.
From here on I don't know exactly how it went from here.
As far as I suspect, more calibration fields were then added and the other strong / weak interactions introduced.
The whole standard model is unfortunately completely inelegant - it's a huge patchwork quilt, but it works quite well until now.

I think it's important that you describe the development. Nobody came up with the standard model one morning in the toilet.
Technical details are rather boring and alienate your audience, try to convey concepts (the idea behind).

Unfortunately, I don't know how much time you have left and what the demands of your work should be. Sorry if I confused you now.

No, I'm supposed to write a term paper directly on the standard model. It has to be ready by Friday. As txt. Document is really stupid to look over again! I shouldn't write more than a maximum of 10 pages (including table of contents, sources, cover sheet). There is no long speech left open.
@ Hamilton. I think that's good too, that's how I would have wanted to start, but I think that they really drifted off because they can't do anything with all these terms, I would have to explain that again and that takes time if the lecture lasts a maximum of 15 minutes should;) thanks anyway :-) if I write a technical paper soon: D I will incorporate your style;) (plan to write a technical paper on string theory)

mfg herry

@ Hamilton. I think that's good too, that's how I would have wanted to start, but I think that they really drifted off because they can't do anything with all these terms, I would have to explain that again and that takes time if the lecture lasts a maximum of 15 minutes should ;)

What can you get across in 15 minutes using the standard model? If they are already sleeping away at Hamilton's example, then especially with your listing (sorry, it doesn't mean bad).
I would take Hamilton's advice to heart and tell more about the history of the Standard Model than any boring details like up-quark lifetimes, spin quantum numbers, and the like. At the end you can still briefly distribute a copy with all previous types of particles and all kinds of physical data.

I think @EMI once posted a very detailed list of the elementary particles that have been discovered so far. Or?

plan to write a thesis on string theory

Well, if that's all. 3 minutes are enough to get it across in an understandable way. : D

I think @EMI once posted a very detailed list of the elementary particles that have been discovered so far. Or?

Hello Lorenzy,

do you mean that:

The following status of current research:

There are 3 electrically charged leptons (one of which is the electron).
There are 3 el.uncharged leptons (Neutrionos).
There are 6 electrically charged and colored quarks (here the electric charge is divided into thirds).
These 12 are the BASIC BUILDING BLOCKS of matter in the universe.
The 12 are still divided into 3 families whereby the visible matter in the universe consists only of members of the 1st family.
It is not yet known whether the 12 are made up of even smaller sub-structure particles.

The hadrons are "built up" from the quarks. There are hundreds of hadrons.
Hadrons are subdivided again:
1. Baryons (consist of 3 quarks), protons and neutrons belong to the baryons.
2. Mesons (consist of a quark pair -quark / antiquark-).

There is an antiparticle for every lepton, quark and hadron.

Then there are the field bosons. These are the power transmitters of the 4 basic fields of physics:
1. electromagnetic force = photon
2. weak force = field boson W +, W- and Z
3. strong force = 8 pieces of gluons (carry color charge)
4. Gravitational force = Graviton (not yet found / proven to this day).

And last but not least, we have the Higgs particle, also a boson.
According to the theory, this should give matter the mass.
This Higgs has not yet been found either, the LHC is looking for it.

The leptons and quarks have spin = ½, baryons have half-integer and mesons have integer spin. The field bosons have spin = 1, except the graviton that has spin = 2.
Particles with half-integer spin are also called fermions, they are subject to the Pauli principle.

The atoms are made up of the two baryons (proton + neutron) and the lepton (electron).

Greetings EMI

The list was from a link. A table with all kinds of kaons, pions, mesons, hyperons and whatever else there is. Or did someone else post it? Was about 2 months ago.

A table with all kinds of kaons, pions, mesons, hyperons and whatever else there is.

Hello Lorenzy,

Kaons, pions are mesons.
Hyperons are baryons.

Hadrons are divided into mesons and baryons, the "other" are the names of the individual mesons or baryons, just like a lepton is named electron.

Greetings EMI

(I plan to write a thesis on string theory)
If you know what's good for you, you better not do it.

I also find the story with the standard model a bit strange - the subject is extremely cool, but in my opinion it doesn't belong in school.
Without knowing the basics, you can certainly represent all the facts and show nice diagrams of hadrons and lepton families, but without having any idea where it all comes from and what that means, it is not worth much - that’s such a " That's so - and it's over "- lecture and I have always not really liked it.
It's not necessarily your fault if you got the topic as homework, but if you can choose the topic for a specialist thesis, then keep your hands off string theory, because in order to be able to say something intelligent you would have to do that first Fill the vacuum in between and become pretty good at (relativistic) quantum mechanics and quantum field theory, and I consider that to be asking too much for a 13th grade student, even if this student is top of the class in physics anyway and all the pop books by Hawking and co. devours.

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