B What Are the Origins of IR and UV Terminology in Particle Physics?

[star apple]

I assume UV means high energy (small scale) and IR is low energy (large scale).. but what is the exact origin of its use in particle physics? Why IR, UV, and not Gamma?

Thank you.

 

[berkeman]

I assume UV means high energy (small scale) and IR is low energy (large scale).. but what is the exact origin of its use in particle physics? Why IR, UV, and not Gamma?

Thank you.

What do those abbreviations stand for?

And what does the equation E=hν represent?

 

[rootone]

="star apple, post: 5870221, member: 632800"Why IR, UV, and not Gamma?
Thank you.

Because IR and UV are both within the domain which is interesting to most humans.
While gamma rays are also interesting, they are nasty, most people really don't want to play with it.

 

[davenn]

Because IR and UV are both within the domain which is interesting to most humans.
While gamma rays are also interesting, they are nasty, most people really don't want to play with it.

not really relevant within the context of the OP question

Why IR, UV, and not Gamma?

cuz they describe different parts of the EM spectrum

Do some research to find out where in the spectrum each of those are relative to each other
and what they are, then answer @berkeman's Q Dave

 

[star apple]

What do those abbreviations stand for?

And what does the equation E=hν represent?

Of course UV means Ultraviolet as skin sunblock offers UV protection and IR means Infrared Red from the IR camera or remote control. I just wonder why are these always mentioned in high energy physics. E=hv is used to calculate the energy of electromagnetic radiation, and is known as the Planck-Einstein relation. "E" is the energy of electromagnetic radiation, "h" is the Planck constant and "v" is the frequency of electromagnetic radiation. Does it mean when v corresponds to UV and IR, the E corresponds to certain energy scale directly used in particle physics??

 

[davenn]

I just wonder why are these always mentioned in high energy physics.

give a link to an example of that

did you find out where on the spectrum they are relative to each other ?

 

[star apple]

give a link to an example of that

did you find out where on the spectrum they are relative to each other ?

for the link: https://arxiv.org/pdf/0801.2562.pdf

for the spectrum:

IR wavelength in meters: 10^-5
UV wavelength in meters: 10^-8

How's it related to high energy physics? In the energy of the photons? But why is there no radio or gamma cutoff being mentioned.. I only read about IR or UV cutoff.

 

[Drakkith]

I just wonder why are these always mentioned in high energy physics.

As far as I'm aware, UV and IR are of essentially no interest to particle physicists, as both are of relatively low energy compared to the EM radiation produced during decay processes that turn one or more particles into others.

Does it mean when v corresponds to UV and IR, the E corresponds to certain energy scale directly used in particle physics??

I don't believe so.

 

[star apple]

As far as I'm aware, UV and IR are of essentially no interest to particle physicists, as both are of relatively low energy compared to the EM radiation produced during decay processes that turn one or more particles into others.
I don't believe so.

See page 11 of https://arxiv.org/pdf/1710.07663.pdf for example

"A theory that manifests an active interplay between the IR and the UV would not be
simply describable by an effective field theory, as it would violate its inner logic. It is not
impossible that quantum gravity will exhibit some kind of IR/UV interplay. An indication
could come from the classical behaviour of gravity. Consider the head-on collision of two
particles at ever increasing energies. Once you pass the threshold for forming a black hole,
the more energy you feed in the system the larger the Schwarzschild radius becomes. In
other words, higher energy collisions are less sensitive to short distances, in contrast with
our effective-theory intuition for a separation between IR and UV."

What is the context of IR and UV in particle physics?

 

[Drakkith]

See page 11 of https://arxiv.org/pdf/1710.07663.pdf for example

"A theory that manifests an active interplay between the IR and the UV would not be
simply describable by an effective field theory, as it would violate its inner logic. It is not
impossible that quantum gravity will exhibit some kind of IR/UV interplay. An indication
could come from the classical behaviour of gravity. Consider the head-on collision of two
particles at ever increasing energies. Once you pass the threshold for forming a black hole,
the more energy you feed in the system the larger the Schwarzschild radius becomes. In
other words, higher energy collisions are less sensitive to short distances, in contrast with
our effective-theory intuition for a separation between IR and UV."

What is the context of IR and UV in particle physics?

From my little reading on this, I think that UV simply refers to an arbitrarily large energy scale above the visible spectrum. I assume IR is the scale under the visible or under the UV range. From wikipedia's article on UV completion:

The word "ultraviolet" in this so-called "ultraviolet regime" is only figurative, and refers to energies much higher than ultraviolet light per se. Rather, by analogy to the relationship between ultraviolet and visible light, it refers to energies higher than (and wavelengths shorter than) those "visible" to laboratory experiment.
...
There is an analogous phrase "infrared completion", which applies to length scales longer than those "visible" to normal experiment, particularly cosmology distances.

 

[star apple]

From my little reading on this, I think that UV simply refers to an arbitrarily large energy scale above the visible spectrum. I assume IR is the scale under the visible or under the UV range. From wikipedia's article on UV completion:

Thanks, so the word UV in HEP is only figurative.. and IR too.. good to know...

"In theoretical physics, ultraviolet completion, or UV completion, of a quantum field theory is the passing from a lower energy quantum field theory to a more general quantum field theory above a threshold value known as the cutoff. In particular, the more general high energy theory must be well-defined at arbitrarily high energies.

The word "ultraviolet" in this so-called "ultraviolet regime" is only figurative, and refers to energies much higher than ultraviolet light per se. Rather, by analogy to the relationship between ultraviolet and visible light, it refers to energies higher than (and wavelengths shorter than) those "visible" to laboratory experiment.

The ultraviolet theory must be renormalizable; it can have no Landau poles; and most typically, it enjoys asymptotic freedom in the case that it is a quantum field theory (or at least has a nontrivial fixed point). However, it may also be a background of string theory whose ultraviolet behavior is at least as good as that of renormalizable quantum field theories. Besides these two known examples (QFT and string theory), it could be a completely different theory than string theory that behaves well at very high energies.

There is an analogous phrase "infrared completion", which applies to length scales longer than those "visible" to normal experiment, particularly cosmology distances"