Unparticles may provide a new path to superconductivity

April 7, 2015 by Lisa Zyga, Phys.org feature

Unparticles may emerge when, at high energies, the particle sector couples to the unparticle sector. Physicists plan to look for the signatures of unparticles in future experiments, possibly by looking for strange superconducting behavior. Credit: LeBlanc and Grushin. CC-BY-3.0
(Phys.org)—Physicists have proposed that a hypothetical form of matter called "unparticles" may play a key role in mediating superconductivity—the ability of certain materials to conduct electricity with zero resistance.

Physicists James LeBlanc and Adolfo Grushin at the Max Planck Institute for the Physics of Complex Systems in Dresden (LeBlanc is now with the University of Michigan in Ann Arbor) have published a paper on their proposal of unparticle-mediated superconductivity in a recent issue of the New Journal of Physics.

"Understanding all forms of superconductivity remains one of the holy grails of modern physics," Grushin told Phys.org. "Proposing new ways of how this astonishing phenomena can emerge is of key importance to push the frontier of knowledge that deals with how materials can superconduct. By identifying how unparticles contribute to superconductivity, we open a new path to possibly finding unparticles, by looking for strange superconducting behavior. Moreover, the novelty and broadness of our approach can inspire other researchers to look for this new type of superconductivity in nature."

The basic theory of superconductivity involves forming Cooper pairs due to a very small attraction between electrons in a metal. In some , the electrons are thought to be bound together by phonons. However, in many materials, the underlying mechanisms that cause this pairing are still not well understood: what is the "glue" that holds these pairs together? One thing that is clear is that, in order for electrons to form pairs and move with zero resistance, they must behave in a very complex way.

Here, LeBlanc and Grushin have investigated the possibility that this complex electronic behavior arises from the presence of unparticles. As their name suggests, unparticles do not behave like particles. While a particle's mass always stays the same, even though its energy and momentum may change, unparticles are different. In an unparticle, all three of these properties—mass, energy, and momentum—must scale up or down equally. Photons, because they are massless, are actually considered scale-invariant, but are not unparticles. Unparticles are a hypothetical form of matter that also have scale-invariance but not zero mass. Instead, this strange "unparticle stuff" is a collection of massive particles, which together appear scale-invariant and behave, at least in a sense, as if they have zero mass.

In their paper, LeBlanc and Grushin show that, if unparticles were present in superconductors, then they would assist the normal electrons in pairing, acting as the glue that holds them together in Cooper pairs. As a result, the material can become superconducting.

The physicists explain that this unparticle-mediated superconductivity would be very different than conventional phonon-mediated superconductivity. It's also different than proposals in which a particle acts as the glue, since all of the particles in these proposals have mass.

"We have proposed a very weird glue, which does not have a mass," LeBlanc explained. "As a result, both the glue and the resulting binding strength (the strength of the superconductivity) are different. So we could get superconductivity with an 'unparticle glue' in cases where a 'particle glue' would never superconduct. To top things off, high-temperature superconductors might be one of those places. But this remains to be seen."

Although unparticles have never been experimentally observed, physicists plan to look for their signatures at future LHC experiments.

"Unparticles are hard to observe directly, due to having no density," LeBlanc said. "Therefore, one needs to look at the other particles nearby and see how they react to the presence of unparticles."

If unparticles do play a role in superconductivity, knowing this may help in their search.

"If one can find materials in the lab where these unparticle effects are strong, then this will motivate a lot of work in understanding the subtle interplay of unparticles with particle matter," LeBlanc said.

In the future, the physicists plan to further explore the connections between unparticles and in all possible forms.

"So far, we've tackled how the superconducting glue could be of an unparticle nature," Grushin said. "Other researchers have addressed the situation where electrons, and not their glue, behave as unparticles. But what happens if both glue and electrons are of unparticle nature? Along the way, it is important to explore all of the things that unparticles could do, so that we know where to look and know when we find them. This is where we intend to go."

Explore further: Physicists unlock nature of high-temperature superconductivity

More information: James P. F. LeBlanc and Adolfo G. Grushin. "Unparticle mediated superconductivity." New Journal of Physics. DOI: 10.1088/1367-2630/17/3/033039

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shavera
not rated yet Apr 07, 2015
nb: there's a difference between 'fundamental particles' (like photons, quarks, electrons, and so on), and 'effective field particles' (phonons and other things). The latter arise in specific instances of materials where we can mix a bunch of relevant interacting stuff (like electrons and an atomic lattice and their electromagnetic interactions) into one "effective field" that is a specific approximation to that material
Dethe
2 / 5 (3) Apr 07, 2015
This is essentially the correct insight - the main distinction of classical Type-I superconductors from "high-temperature" Type-II ones is, the electrons don't form a Cooper pairs, but rather Cooper teams with undefined number of electrons inside of "team". But the formation of pairs or teams is not the primary reason of superconductivity in both cases, rather one of the attributes of it. The primary question here is, why these pairs, triplets, etc. are forming there. BTW In dense aether model the unparticles form also the substantial portion of dark matter - they correspond the shapeless ripples and turbulences at the water surface. Their common denominator is, they're difficult to detect in mass energy spectrum, as they form only fuzzy peaks there. The Higgs boson or dark matter fluctuations are also a members of wider unparticle collection.
Dethe
1 / 5 (2) Apr 07, 2015
there's a difference between 'fundamental particles' (like photons, quarks, electrons, and so on), and 'effective field particles'
Yes, the unparticles represent sorta transition between normal well defined particles and rather homogeneous virtual particle field. They also form a transition between fermions and bosons - so called the anyons, which are known from solid phase physics by their fractional charge. The quarks also share some characteristic with unparticles - they do exist in many varieties, they're poorly defined in their free state and they're also of fractional charge. After all, many unstable particles of extreme mass identified in colliders only rarely exist in well defined state - usually they're isolated in one or more excited states, which are poorly defined. The unparticle concept is therefore more widespread, than one may think and it becomes typical for systems of extremely high or extremely low energy densities.
sandler
not rated yet Apr 07, 2015
There this a nice description of Diamagnetism which may be at play here, from Chemistry textbook:
https://www.bound...0-10520/
redge_little
1 / 5 (1) Apr 07, 2015
RBL (in a second longer article "A Theory of the Relativisitic Fermionic Spinrevorbital") also considered in more details (a lot of details) how heat and relative thermal motions are transformed to gravity and gravity to magnetism by magnetic processes for forming continuum spinrevorbitals (unparticles) in stellar objects. I show in this article how such heat to gravity to magnetism is further intrinsically coupled to fermions for binding fermions at higher temperatures for superconductivity beyond current critical temperatures. By this I first proposed in 2005 via sci-print archive and in 2012 via vixra archive and now in Jan 2015 via IJPS that quarks are held by a glue that is magnetic revolutionary (unparticle) for a magnetic basis of strong interactions holding the superfluidic quarks and nucleons in nuclei.
redge_little
1 / 5 (1) Apr 07, 2015
In analog, I realized such weaker magnetic spinrevorbital hold electrons in atoms and molecules for superconductivity in orbitals and in continuum (forbidden states). I thereby realized that such continuum spinrevorbitals in many atoms making up macro-objects can form by macroscopic heat, pressure, macro-electric, gravity, macromagnetic energies to form continuum states of varying mass, momenta and energies for binding currents into high temperature superconductivity beyond room temperature even at extreme temperatures in stellar objects. This is very beautiful!!! See a long article that ties everything together at this website for International Journal of Physical Sciences (Jan 2015) {"A Theory of the Relativistic Fermionic Spinrevorbital"} You can see the abstract at this website and you can also access the whole publication free of charge by clicking on 'full text pdf'.
redge_little
1 / 5 (1) Apr 07, 2015
RBL applied such models to the mechanism of superconductivity and in so noted that heat and relative moving thermal energy relative to fermion can be transformed to gravito-magnetism for nondissipation of motion of fermions for superconductivity and superfluidity! See the short article at the archive {"On the Mechanism of Above Room Temperature Superconductivity and Superfluidity by Relativistic Quantum Mechanics"} .
Dethe
not rated yet Apr 08, 2015
These electrons still repel each other - but they're also attracted to atom nuclei, as Coulomb law implies. The net result is a weak attractive force between electrons.
Dethe
not rated yet Apr 08, 2015
How such attractive force manifest itself, for example? IMO the hydrogen must be compressed very badly with external force for to have it superconductive.
Hyperfuzzy
not rated yet Apr 08, 2015
is this a spatial mode or time mode, or both? Hence, what is the impedance over the frequency domain? Can the Fourier interpretation provide a signal as a function of time and space? The idea of an un-particle may be quite exotic; however, can be misleading. It would be best to define the body-field discreetly within the frequency-time-spatial domain instead of assigning something never observed for what we do not understand. It makes us look as though we do not know what we're talking about. Superconductivity is more like an electron circling a proton with no interference. depending upon the energy within the matter and the atomic structure shall define the freedom of electrons to flow as if they are simply moving freely within a field. identifying obstructions is more definitive. Electron-electron and electron-lattice are two different things.
Hyperfuzzy
not rated yet Apr 08, 2015
The atomic model as a function of energy is hinted by past experience, i.e. present super conductors and meaningful data. However, an atomic model of the existing SC would be more enlightening. Consider building the nucleus with protons and bound electrons that create neutrons. Suspect the outer electrons are best defined as existing within a plane. With simulation with real data we should be able to define a better model. Using only 2 particles and the field seems more realistic. How does the electron plane change? What occurs from the nucleus vibration? What are the lattice interactions to an applied field? Do electrons get bound to the same plane and orbit? May they have opposite rotations thus continuous near collisions? Atom to atom. Magnetic,dE/dt, dH/dt, spin (location & time, repetitions) Allowed or dis-allowed, etc. etc. before creating "un-particles".
Protoplasmix
not rated yet Apr 08, 2015
It would be best to define the body-field discreetly within the frequency-time-spatial domain instead of assigning something never observed for what we do not understand. It makes us look as though we do not know what we're talking about.
'Unparticle stuff' was introduced as a theoretical curiosity with the task of phenomenology left to others, e.g., scientists working on superconductivity (which we don't fully understand).

The wave-like and particle-like duality we observe is a more fundamental aspect we don't fully understand. When the territory is fundamental laws of nature, the map we use is math/logic/postulates.

What I find particularly brilliant about unparticle stuff is that it's not only cognizant of invariance, it actually provides a testable framework for a specific facet of invariance, i.e., scale invariance. See http://arxiv.org/.../0703260
mreda14
not rated yet Apr 10, 2015
The operating principle of electromagnetic generators was discovered in the years of 1831–1832 by Michael Faraday. The principle, later called Faraday's law, is that an electromotive force is generated in an electrical conductor which encircles a varying magnetic flux. In the simplest form of linear electric generator, a sliding magnet moves back and forth through a solenoid - a spool of copper wire. An alternating current is induced in the loops of wire by Faraday's law of induction each time the magnet slides through. This is exactly what happens in for example, the high temperature Cuprate superconductor where the mixed valence copper oxide plane vibrate along the central atom producing a current but because the system in atomic scale, the current produced flow with zero resistance. The idea of un-particle is similar to the idea of count Dracula has no image in the mirror. He is un-dead.

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