'Tunneling of the third kind' experiment could search for new physics

Oct 03, 2012 by Lisa Zyga feature
This diagram shows a photon (wavy line) tunneling through a barrier mediated by a minicharged particle-antiparticle loop. The possibility of tunneling is enhanced by an applied magnetic field. Image credit: Döbrich, et al. ©2012 American Physical Society

(Phys.org)—In an attempt to solve some of the observational puzzles in physics, theorists have proposed a number of new physics models. Several of these models suggest the existence of extremely weakly interacting lightweight particles with tiny fractional electric charges called minicharged particles (MCPs). Constraining the masses of MCPs could help theorists refine their models, but so far it has been very difficult to detect MCPs. Now in a new study, physicists in Germany have proposed a new search for MCPs based on a new tunneling mechanism called "tunneling of the third kind," which could prove very useful in the search for new physics.

The physicists, Babette Döbrich (currently at DESY in Hamburg, Germany), Holger Gies, and Felix Karbstein, working at the Friedrich Schiller University of Jena and the Helmholtz-Institut Jena, both in Jena, Germany, along with Norman Neitz working at the Friedrich Schiller University of Jena (currently at the Max Planck Institute for ), have published their paper on a new search for MCPs in a recent issue of .

"The general idea behind MCPs, as well as other light and weakly interacting , is the following: New particles are mostly assumed to 'hide' at high masses/energies, but they could also have very well eluded our searches if they are light, but weakly coupled," Döbrich told Phys.org. "Particularly, many theories beyond the Standard Model predict a spectrum of new particles at low masses and weak coupling. In some parameter regions they could explain phenomena such as and some astrophysical puzzles. In a nutshell, finding minicharged particles could help us very much in constraining theories proposed beyond the Standard Model."

Although MCPs are very difficult to detect due to their weak coupling, several experiments are currently searching for them. Here, the scientists propose using " of the third kind," which is so named because it was the third kind of tunneling to be discovered. In all three known types of tunneling, a passes through a barrier that a classical particle cannot pass through. In the first kind of tunneling, known simply as standard quantum mechanical tunneling, this phenomenon occurs due to the uncertainty principle, which gives a finite probability that a quantum particle can pass through a barrier.

In the second kind of tunneling, a quantum particle that interacts strongly with the barrier and cannot pass through, such as a photon, is converted to a particle that does not interact with the barrier and can easily pass through. This kind of tunneling is sometimes called "light shining through a wall," and is the basis for some of the current experiments searching for MCPs.

In tunneling of the third kind, a quantum particle that cannot pass through a barrier changes into a pair of virtual particles that pass through the barrier before changing back into the first particle. Gies, along with coauthor Joerg Jaeckel, discovered this kind of tunneling in 2009. They suggested that this tunneling could take the form of photons changing into MCPs, which can tunnel through certain barriers and then change back into photons. Like the second kind of tunneling, this kind would also appear as light shining through a wall.

The physicists in the current study have theoretically shown that experiments involving tunneling of the third kind can potentially detect MCPs with very small masses, including those in the regime suggested by models. The key to such experiments is to apply a strong magnetic field, which can significantly amplify the MCPs' tunneling probability.

In the proposed experimental set-up, a photon travels toward a perfectly opaque wall up to 1.8 cm thick, and behind the wall is a photon detector. The wall is installed in the 0.28-meter-diameter bore of a 1.2-meter-diameter solenoid magnet that provides a very large field strength of 5 Tesla. The large field strength enhances the potential for detecting very low-mass particles such as MCPs as photons appear to pass through the wall.

"The experiment suggested by us is of the light-shining-through-a-wall type," Döbrich said. "Several of these experiments have already been performed, and at the moment two upgrades that push these studies to their limits are proposed (ALPS-II at and REAPR at Fermilab). The experiment suggested by us differs from these setups in the magnetic field configuration, which is optimized in our setup for minicharged particles. This is a consequence of the 'tunneling of the third kind' scenario in contrast to 'tunneling of the second kind,' which previous experiments are based on."

The physicists calculate that this experiment should be sensitive to detecting MCP masses down to 7 x 10-7 eV, which is in the parameter regime of new physics. This sensitivity significantly improves upon the capabilities of other experiments, such as the polarizzazione del Vuoto con laser (PVLAS) experiments and CMB-based cosmological experiments, both of which have been previously used to search for MCPs. As Döbrich explained, detecting photons on the opposite side of the wall would be a clear indication of physics beyond the Standard Model.

"The nice thing about the light-shining-through-a-wall effect is that known (i.e., ) particles cannot produce such an effect within current sensitivities," Döbrich said. "Thus, if light shining through a wall were observed, it would be a clear hint of new physics! As a second step, one would have to determine the nature of this new particle precisely (as ongoing, for example, for the new particle at the LHC, a.k.a. the Higgs boson, whose spin, for example, still has to be determined). In our experiment, changing, for example, the angle of the incident light or changing its polarization would be a way to discriminate minicharged particles from other weakly interacting new particles."

Explore further: The unifying framework of symmetry reveals properties of a broad range of physical systems

More information: Babette Döbrich, Holger Gies, Norman Neitz, and Felix Karbstein. "Magnetically Amplified Tunneling of the Third Kind as a Probe of Minicharged Particles." PRL 109, 131802 (2012) DOI: 10.1103/PhysRevLett.109.131802

Journal reference: Physical Review Letters search and more info website

4.6 /5 (34 votes)

Related Stories

The secrets of tunneling through energy barriers

Nov 07, 2011

Electrons moving in graphene behave in an unusual way, as demonstrated by 2010 Nobel Prize laureates for physics Andre Geim and Konstantin Novoselov, who performed transport experiments on this one-carbon-atom-thick material. ...

3 Questions: Faster than light?

Sep 26, 2011

The news media were abuzz this week with reports of experiments conducted at the Gran Sasso particle detector complex in Italy, apparently showing subatomic particles called neutrinos had traveled from th ...

'The most important discovery in recent decades'

Jul 06, 2012

Interview with Sandra Kortner of the Max Planck Institute for Physics in Munich, who heads a Minerva junior research group at the ATLAS experiment of the LHC and also coordinates an international group of ...

Recommended for you

What time is it in the universe?

Aug 29, 2014

Flavor Flav knows what time it is. At least he does for Flavor Flav. Even with all his moving and accelerating, with the planet, the solar system, getting on planes, taking elevators, and perhaps even some ...

Watching the structure of glass under pressure

Aug 28, 2014

Glass has many applications that call for different properties, such as resistance to thermal shock or to chemically harsh environments. Glassmakers commonly use additives such as boron oxide to tweak these ...

Inter-dependent networks stress test

Aug 28, 2014

Energy production systems are good examples of complex systems. Their infrastructure equipment requires ancillary sub-systems structured like a network—including water for cooling, transport to supply fuel, and ICT systems ...

User comments : 18

Adjust slider to filter visible comments by rank

Display comments: newest first

hemitite
4.7 / 5 (3) Oct 03, 2012
There was a similar technique was used a few years back to look for Axions:
http://en.wikiped...ki/Axion
Arcbird
1.4 / 5 (8) Oct 03, 2012
Why are every single sinewave always pictured in 2D ???
vega12
4.9 / 5 (7) Oct 04, 2012
Why are every single sinewave always pictured in 2D ???


1) y = sin(x) has 2 dimensions
2) How many dimensions does your monitor's display have?
typicalguy
not rated yet Oct 04, 2012
The magnetic field at the place of barrier would accelerate the mutual recombination of these pairs, because they're A) in motion B) they're of opposite charge, thus enforcing the photon state, thus making the tunneling of photons easier. Another, even more illustrative explanation provides the particle model of vacuum, in which the obstacle represents the more dense barrier inside of vacuum foam. The introduction of magnetic field would make the vacuum foam more dense and the obstacle less dense and less significant relatively - so that the photon can tunnel through it easier.


What part of standard particles can't make it through the barrier do you not understand?
Electronhelix
1.6 / 5 (5) Oct 04, 2012
Why are every single sinewave always pictured in 2D ???


1) y = sin(x) has 2 dimensions
2) How many dimensions does your monitor's display have?

It is interesting but,without us recognizing it, we are continually brainwashed by the accepted Mathematical representation of a Photon.(Mathematical as in the representation of a photon in a 2D graphical form, with just a nod to the Magnetic component even in Physics text books) The Electrostatic and Magnetic functions would be better understood as a 'shaded' envelope decreasing in intensity across the wave front from the axis. This signifying decreasing magnitude.
A further misconception is that Electromagnetic Waves travel as individual entities. It would be more correct if the visualization was a Maelstrom of Electrostatic and Magnetic fields, all as added vectors, in a similar fashion to the turbulence of water in the immediate wake of a ship's propellers. All wave magnitudes, from Cosmic to Ultra long waves, combining.
antialias_physorg
4.6 / 5 (7) Oct 04, 2012
we are continually brainwashed by the accepted Mathematical representation

I would disagree with this. It is the accepted mathematical/physical representation used in accepted mathematical/physical media (jouranls, papers, books, etc.)

If you try to read those books but don't bother to learn the symbols used - whose fault is it? Certainly mathematicians/physicists aren't confused by the 'wavy line' representation.

Only laymen that want to play at being scientists without making any effort to learn anything (read: people to whom the Dunning-Kruger effect applies, bigtime) are confused.
Egleton
1.8 / 5 (4) Oct 04, 2012
Oops. There goes the Coulomb Barrier. Let the fun begin.
antialias_physorg
5 / 5 (5) Oct 04, 2012
People to whom the Dunning-Kruger effect applies are all people, who are believing, they're not subject of Dunning-Kruger effect.

Exactly.

So to know whether it applies to you or not needs a different avenue of approach. If you have the track record to suggest that you do valuable scientific work then it may not apply. If you don't then it probably does.
(Note that for both cases there is a small possibility that it is not so. But if you bank on being part of that small percentage then you're likely "Dunning-Kruger"-ing yourself again)
adwarakanath
5 / 5 (4) Oct 04, 2012
What is it about this website that attracts nutjobs? If you guys really think mainstream, well-researched, evidenced science is wrong, I challenge you to go post on Nature or Science and get someone publishing there to listen to you and seriously consider your "hypotheses".
antialias_physorg
5 / 5 (6) Oct 04, 2012
I challenge you to go post on Nature or Science and get someone publishing there to listen to you and seriously consider your "hypotheses".

Ah. I think you have not fathomed the depth of their 'nutjobness'. They think that there exists a global conspiracy and scientific cabal that has the power to prevent publications by them (even though papers go through ANONYMOUS peer review, and the anonymisation isn't done by scientist but by journalists/editors)

So not only does there exist a global conspiracy against them, but it is a conspiracy of mindreading indidviduals, no less.

Yep: conspiracy theorists are pretty crazy. But the hallmark of craziness is: they don't know they are crazy.
FastEddy
1 / 5 (3) Oct 05, 2012
" ... we are continually brainwashed by the accepted Mathematical representation ..."

"... suggest the existence of extremely weakly interacting lightweight particles with tiny fractional electric charges called minicharged particles (MCPs). ..."

Egleton:
Oops. There goes the Coulomb Barrier. Let the fun begin.


And all of this "quantum" nonsense as well. Einstein rules!
FastEddy
1 / 5 (3) Oct 05, 2012
Why are every single sinewave always pictured in 2D ???

1) y = sin(x) has 2 dimensions
2) How many dimensions does your monitor's display have?


It is thought that we might have holographic monitors by now ...
FastEddy
1 / 5 (2) Oct 05, 2012
... we are continually brainwashed by the accepted Mathematical representation ...


I would disagree with this. It is the accepted mathematical/physical representation used in accepted mathematical/physical media (jouranls, papers, books, etc.) ... Only laymen that want to play at being scientists without making any effort to learn anything (read: people to whom the Dunning-Kruger effect applies, bigtime) are confused.


Of course all too many wordsmiths' thinking is totally linear, focused on the two dimensional page. Some can think and visualize in three dimensions ... and very few can add to that the visualization of time ... A real world audio sign wave is three dimensional and moves forward through time as well ... Personally I find it troubling visualizing that Quarks are indivisible ... Thus the fascination with this article.
FastEddy
1 / 5 (3) Oct 05, 2012
" ... "The nice thing about the light-shining-through-a-wall effect is that known (i.e., Standard Model) particles cannot produce such an effect within current sensitivities," Döbrich said. "Thus, if light shining through a wall were observed, it would be a clear hint of new physics! ..."

Or, at the least, an indication of the residual thermal effects caused by the light, possibly measurable on the dark side of the wall.
antialias_physorg
5 / 5 (5) Oct 05, 2012
Or, at the least, an indication of the residual thermal effects caused by the light, possibly measurable on the dark side of the wall.

That would be noticeable via lag (as absorbed and remitted photons are subject to the speed of light limit in the material) - while tunneling particles aren't.
FastEddy
1 / 5 (2) Oct 05, 2012
... If you guys really think mainstream, well-researched, evidenced science is wrong, I challenge you to go post on Nature or Science and get someone publishing there to listen to you and seriously consider your "hypotheses". ...


One might try the Half Bakery instead? ( http://www.halfbakery.com )

There are those of us who welcome this exchange ... and to the neither regions with the tenured good ol' boys.
SteveL
not rated yet Oct 06, 2012
Dunning-Kruger effect
Had to look that one up. ;)
savvys84
not rated yet Oct 08, 2012
I challenge you to go post on Nature or Science and get someone publishing there to listen to you and seriously consider your "hypotheses".

Ah. I think you have not fathomed the depth of their 'nutjobness'. They think that there exists a global conspiracy and scientific cabal that has the power to prevent publications by them (even though papers go through ANONYMOUS peer review, and the anonymisation isn't done by scientist but by journalists/editors)

So not only does there exist a global conspiracy against them, but it is a conspiracy of mindreading indidviduals, no less.

Yep: conspiracy theorists are pretty crazy. But the hallmark of craziness is: they don't know they are crazy.

Yes there may be some opposition from parties with vested interests or simply preventing cutting edge physics that has defense implications from being published in sceintific journals, even though substatiated with undeniable visible proof.