A simple explanation of quarks and leptons

[DrWhoF]

Can someone explain to me in layman's terms what Quarks and Leptons are???

 

[IanP]

Re: quarks and leptons

Quarks and Leptons are believed to be the twelve fundamental particles of matter ..
Quarks and Leptons are distinguished by the different ways in which they react to the fundamental forces (gravitational, electromagnetic and strong and weak nuclear) ..

The six quarks are called: up, down, strange, charm and top (in order of mass) ..
The six leptons are the electron, the electron-neutrino, the muon, muon-neutrino, tau and tau-neutrino ..
Quarks are particles with fractional charge ..
Leptons (electron, muon and tau) all have charge of (-1), neutrinos – no charge (0) ..

Normal matter (incl. protons and neutrons) consists of combinations of two quarks: the up quark u and the down quark d.
Proton => uud
Neutron =>udd


All matter is composed of atoms which are constructed from electrons which orbit round a small, heavy, positively charged nucleus ..
In turn the nucleus is composed of protons, which have a positive charge, and neutrons, which are uncharged ..
In turn protons and neutrons are composed of quarks ..

Among leptons, the familiar thing is the electron, which is one of the constituents of the atom and the particle that is responsible for the electric current ..

Some of these particles do not occur in usual matter but may be created by sufficiently powerful accelerators ..


And the story stops at this point, as these particles are thought to be fundamental – they are all distinct and there are no pieces within them ..

Rgds,
IanP

PS. google for the pdf of: "Quarks Leptons and the Big Bang" by J. Allday ..

 

[karesz]

quarks and leptons

Hi,
you can read such "original" publications too from: www.desy.de as the one "bakings source of physics"...
K.
This was in former times of ca. 10 years "material" of accelerating ring & detector groups Hera & H1...

 

[kokabanga]

Re: quarks and leptons

As our knowledge of physics grows, so we discover smaller and smaller particles. Can this continue forever, or are there fundamental particles, which we can't break down any further? Our current understanding of physics leads us to believe that there do indeed exist these particles, from which we can create the structures we know about. They are Leptons and Quarks.

Leptons
These are particles such as muons and electrons, there are 6 leptons in total, each with their anti-lepton counterpart. For the electron, muon and taon (which are referred to as different flavours of the lepton) there is a corresponding neutrino (a lepton) associated with it. Leptons do not participate in the strong interaction and are generally not seen within the nucleus.

Type Flavour
Charge as a ratio of |e|
lepton e m t -1
lepton-neutrino ue um ut 0

For more information on leptons click here

Quarks
The term 'quark' was introduced by Murray Gell-Mann, the word originating from the book 'Finnegan's Wake' by James Joyce in which the quotation 'Three quarks for Muster Mark' appears. We now know there are are six quarks (or called flavours of quarks), which are grouped into 3 pairs (or generations); up & down, charmed & strange and top and bottom. It is these fundamental particles which form neutrons, protons etc, which are collectively known as hadrons, (it is mainly the up and down which form the world around us). The quarks are peculiar as they posses a charge which is a fraction of that for the electron. Take for example the proton, it has charge +1 and is formed from up and down quarks so the only combination available is 2 up quarks and a down.

Name Symbol charge Mass (approx.,GeV/c2)
Down d -1/3 0.008
Up u +2/3 0.004
Strange s -1/3 0.15
Charm c +2/3 1.5
Bottom b -1/3 4.5
Top t +2/3 180

There are two types of hadron, the Baryon which is a system of three quarks (e.g. the proton) or Mesons, a two quark system containing a quark - antiquark pair (e.g. the pion or pi-meson). Baryons are usually confined within nuclei as are unstable and decay if isolated, for example a neutron has a lifetime of about fifteen minutes if not inside the nucleus. The exception to this is the proton which is essentially stable in free space.

 

[IanP]

Re: quarks and leptons

You may also be interested in this one:

UNDERSTANDING UNIVERSE
From Quarks to the Cosmos
Don Lincoln
Fermi National Accelerator Laboratory, USA


**broken link removed**

Rgds,
IanP

 

[DrWhoF]

Re: quarks and leptons

Actually which particles are responsible for the electromagnetic field?

 

[AdvaRes]

Re: quarks and leptons

Actually which particles are responsible for the electromagnetic field?

If you wanna understand all that issues I think that the Theory of Everything can provide replies to your question.

 

[IanP]

Re: quarks and leptons

Photons are the (massless) particles that make up the electromagnetic field ..
Here is an intersting discussion on this issue:
https://www.physicsforums.com/showthread.php?t=176935

Rgds,
IanP

 

[DrWhoF]

Re: quarks and leptons

OK.
How I can undestand spin in particles, is it comparab;le with a spinning tennis ball?
Is there a particle which does not have spin?

 

[IanP]

Re: quarks and leptons

The answer to your first question is: NO ..
See:
**broken link removed**

The second question can only be answered hypothetically , as a scalar particle hasn't been found yet ..
See:
https://en.wikipedia.org/wiki/Higgs_boson

Rgds,
IanP

 

[neils_arm_strong]

Re: quarks and leptons

Intresting []
and i was thinking spin is same as the
mechanical spin

 

[IanP]

Re: quarks and leptons

Of course it is very interesting ..

In the attached book (Creation Revisited) you will find even more interesting things: how to creat something out of nothing ..

**broken link removed**

Rgds,
IanP

 

[DrWhoF]

Re: quarks and leptons

How something can be created out of nothing????

 

[IanP]

Re: quarks and leptons

Then read this book ..

**broken link removed**

 

[IanP]

Re: quarks and leptons

Anonymous wrote this:

Is nothing something?

The point of nothing - to paraphrase Bertrand Russell on philosophy - is to start with something so simple as to seem not worth examining, and to end with something so paradoxical that no one will believe it.

There is more to nothing than meets the eye. What I want to do, with those who want to contribute here, is to try to discover what it is all about, while showing that thinking about nothing means thinking about everything. History, philosophy, religion, art, literature, politics, science - all are touched by nothing. Who could have believed that nothing would turn out to be so interesting, so laden with intrigue, mystery and hidden information?

There is nothing frivolous about nothing; it is pivotal in many subjects and has been examined with various degrees of respect and wonder through the ages. Theologians had been disturbed by it and worried about the concept of creating something out of nothing. It was a difficult topic for Greek philosophers, Medieval and Late Ancient thinkers and for mathematicians. Far from being nothing to worry about, it was a concept that threatened the foundation of what people held dear. The Greeks were scared of it and Aristotle wouldn’t permit it, so that due to the Catholic Church’s embrace of Aristotelianism, Western science and mathematics were held back for centuries.

What is this nothing, that we can’t actually see, touch or feel? Is it absolute? Is it relative to everything else? If we are able to think about it, is it something, and if so wouldn’t it not be nothing?

This is precisely the mystery of nothing – that the more we think about it, the more there is to it.

So is nothing something?

 

[IanP]

Re: quarks and leptons

This time not anonymus, but PAUL DAVIES (he is a theoretical physicist and professor of natural philosophy at the University of Adelaide, South Australia) wrote this:

What Happened Before the Big Bang?
...

If the big bang was the beginning of time itself, then any discussion about what happened before the big bang, or what caused it-in the usual sense of physical causation-is simply meaningless. Unfortunately, many children, and adults, too, regard this answer as disingenuous. There must be more to it than that, they object.

Indeed there is. After all, why should time suddenly "switch on"? What explanation can be given for such a singular event? Until recently, it seemed that any explanation of the initial "singularity" that marked the origin of time would have to lie beyond the scope of science. However, it all depends on what is meant by "explanation." As I remarked, all children have a good idea of the notion of cause and effect, and usually an explanation of an event entails finding something that caused it. It turns out, however, that there are physical events which do not have well-defined causes in the manner of the everyday world. These events belong to a weird branch of scientific inquiry called quantum physics.

Mostly, quantum events occur at the atomic level; we don't experience them in daily life. On the scale of atoms and molecules, the usual commonsense rules of cause and effect are suspended. The rule of law is replaced by a sort of anarchy or chaos, and things happen spontaneously-for no particular reason. Particles of matter may simply pop into existence without warning, and then equally abruptly disappear again. Or a particle in one place may suddenly materialize in another place, or reverse its direction of motion. Again, these are real effects occurring on an atomic scale, and they can be demonstrated experimentally.

A typical quantum process is the decay of a radioactive nucleus. If you ask why a given nucleus decayed at one particular moment rather than some other, there is no answer. The event "just happened" at that moment, that's all. You cannot predict these occurrences. All you can do is give the probability-there is a fifty-fifty chance that a given nucleus will decay in, say, one hour. This uncertainty is not simply a result of our ignorance of all the little forces and influences that try to make the nucleus decay; it is inherent in nature itself, a basic part of quantum reality.

The lesson of quantum physics is this: Something that "just happens" need not actually violate the laws of physics. The abrupt and uncaused appearance of something can occur within the scope of scientific law, once quantum laws have been taken into account. Nature apparently has the capacity for genuine spontaneity.
It is, of course, a big step from the spontaneous and uncaused appearance of a subatomic particle-something that is routinely observed in particle accelerators-to the spontaneous and uncaused appearance of the universe. But the loophole is there. If, as astronomers believe, the primeval universe was compressed to a very small size, then quantum effects must have once been important on a cosmic scale. Even if we don't have a precise idea of exactly what took place at the beginning, we can at least see that the origin of the universe from nothing need not be unlawful or unnatural or unscientific. In short, it need not have been a supernatural event.

...

Well, I didn't promise to provide the answers to life, the universe, and everything, but I have at least given a plausible answer to the question I started out with: What happened before the big bang?
The answer is: Nothing.

Leptons .. quarks .. nothing .. what the hell ..

**broken link removed**

 

[DrWhoF]

Re: quarks and leptons

Thank you for the quotations. Very interesting indead :!:

 

[AdvaRes]

Re: quarks and leptons

Did you heard about the string theory ?
According to this theory it is possible that parallel universes exist. Each univers is inside a membrane that they call brane. Some guys says that the big bang is non other than the result of the contact of two Branes. According to these guys other big bangs happened before the one that we know and other will also happen in the future.

Personly I dont believe in that science fiction.

 

[IanP]

Re: quarks and leptons

Q: Is Hell Exothermic or Endothermic? Support your answer with proof
..
A: First, We postulate that if souls exist, then they must have some mass. If they do, then a mole of souls can also have a mass. So, at what rate are souls moving into hell and at what rate are souls leaving? I think we can safely assume that once a soul gets to hell, it will not leave.

Therefore, no souls are leaving. As for souls entering hell, let's look at the different religions that exist in the world today. Some of these religions state that if you are not a member of their religion, then you will go to hell. Since there are more than one of these religions and people do not belong to more than one religion, we can project that all people and souls go to hell. With birth and death rates as they are, we can expect the number of souls in hell to increase exponentially.

Now, we look at the rate of change in volume in hell. Boyle's Law states that in order for the temperature and pressure in hell to stay the same, the ratio of the mass of souls and volume needs to stay constant. Two options exist:

If hell is expanding at a slower rate than the rate at which souls enter hell, then the temperature and pressure in hell will increase until all hell breaks loose.
If hell is expanding at a rate faster than the increase of souls in hell, then the temperature and pressure will drop until hell freezes over.
So which is it? If we accept the quote given to me by Theresa Manyan during Freshman year, "that it will be a cold night in hell before I sleep with you" and take into account the fact that I still have NOT succeeded in having sexual relations with her, then Option 2 cannot be true ...

Thus, hell is exothermic ...

said student Tim Graham ...

 

[AdvaRes]

Re: quarks and leptons

Q: Is Hell Exothermic or Endothermic? Support your answer with proof
..
A: First, We postulate that if souls exist, then they must have some mass. If they do, then a mole of souls can also have a mass. So, at what rate are souls moving into hell and at what rate are souls leaving? I think we can safely assume that once a soul gets to hell, it will not leave.

Therefore, no souls are leaving. As for souls entering hell, let's look at the different religions that exist in the world today. Some of these religions state that if you are not a member of their religion, then you will go to hell. Since there are more than one of these religions and people do not belong to more than one religion, we can project that all people and souls go to hell. With birth and death rates as they are, we can expect the number of souls in hell to increase exponentially.

Now, we look at the rate of change in volume in hell. Boyle's Law states that in order for the temperature and pressure in hell to stay the same, the ratio of the mass of souls and volume needs to stay constant. Two options exist:

If hell is expanding at a slower rate than the rate at which souls enter hell, then the temperature and pressure in hell will increase until all hell breaks loose.
If hell is expanding at a rate faster than the increase of souls in hell, then the temperature and pressure will drop until hell freezes over.
So which is it? If we accept the quote given to me by Theresa Manyan during Freshman year, "that it will be a cold night in hell before I sleep with you" and take into account the fact that I still have NOT succeeded in having sexual relations with her, then Option 2 cannot be true ...

Thus, hell is exothermic ...

said student Tim Graham ...

What if souls is massless like photons ?

Actually the Hell is not Exothermic nor endothermic (even is soul has mass). Its temperature is constant.
Also the volume/Mass is constant even if you add moles of souls. Like inside a black hole the hell can maintain its characteristics in term of Temp/Mass/Volume thanks to Hawking radiations for exemple or other phenomenon not discoverd yet. (Or maybe will not be discovered forever).