Experiment confirms fundamental symmetry in nature

September 21, 2015
This is the "South Pillar" region of the star-forming region called the Carina Nebula. Like cracking open a watermelon and finding its seeds, the infrared telescope "busted open" this murky cloud to reveal star embryos tucked inside finger-like pillars of thick dust. Credit: NASA

Scientists working with ALICE (A Large Ion Collider Experiment), a heavy-ion detector on the Large Hadron Collider (LHC) ring, have made precise measurements of particle mass and electric charge that confirm the existence of a fundamental symmetry in nature. The investigators include Brazilian researchers affiliated with the University of São Paulo (USP) and the University of Campinas (UNICAMP).

The findings, reported in a paper published online in Nature Physics on August 17, led the researchers to confirm a fundamental symmetry between the nuclei of the particles and their antiparticles in terms of charge, parity and time (CPT).

These measurements of particles produced in high-energy collisions of heavy ions in the LHC were made possible by the ALICE experiment's high-precision tracking and identification capabilities, as part of an investigation designed to detect subtle differences between the ways in which protons and neutrons join in nuclei while their antiparticles form antinuclei.

"After the Big Bang, for every particle of matter an antiparticle was created. In particle physics, a very important question is whether all the laws of physics display a specific kind of symmetry known as CPT, and these measurements suggest that there is indeed a fundamental symmetry between nuclei and antinuclei," said Marcelo Gameiro Munhoz, a professor at USP's Physics Institute (IF) and a member of the Brazilian team working on ALICE.

Munhoz is the principal investigator for the research project "High-energy nuclear physics at RHIC and LHC", supported by São Paulo Research Foundation (FAPESP). The project—a collaboration between the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory in the United States and ALICE at the LHC, operated by the European Organization for Nuclear Research (CERN) in Switzerland—consists of experimental activities relating to the study of relativistic heavy-ion collisions.

Among other objectives, the Brazilian researchers involved with ALICE seek to understand the production of heavy quarks (charm and bottom quarks) based on the measurement of electrons using an electromagnetic calorimeter and, more recently, Sampa, a microchip developed in Brazil to study rarer phenomena arising from heavy-ion collisions in the LHC.

The experiment

According to Munhoz, the measurements of mass and charge performed in the symmetry experiment, combined with other studies, will help physicists to determine which of the many theories on the fundamental laws of the universe is most plausible.

"These laws describe the nature of all matter interactions," he said, "so it's important to know that physical interactions aren't changed by particle charge reversal, parity transformation, reflections of spatial coordinates and time inversion. The key question is whether the laws of physics remain the same under such conditions."

In particular, the researchers measured the mass-over-charge ratio differences for deuterons, consisting of a proton and a neutron, and antideuterons, as well as for nuclei of helium-3, comprising two protons and one neutron, and antihelium-3. Recent measurements at CERN compared the same properties of protons and antiprotons at high resolution.

The ALICE experiment records high-energy collisions of lead ions at the LHC, enabling the study of matter at extremely high temperatures and densities.

The lead-ion collisions provide an abundant source of particles and antiparticles, producing nuclei and the corresponding antinuclei at nearly equal rates. This allows ALICE to make a detailed comparison of the properties of the nuclei and antinuclei that are most copiously produced.

The experiment makes of both the curvature of particle tracks in the detector's magnetic field and the particles' time of flight and uses this information to determine the mass-to-charge ratios for and antinuclei.

The high precision of the time-of-flight detector, which determines the arrival time of particles and antiparticles with a resolution of 80 picoseconds and is associated with the energy-loss measurement provided by the time-projection chamber, allows the scientists involved to measure a clear signal for deuterons/antideuterons and helium-3/antihelium-3, the particles studied in the similarity experiment.

Explore further: The ALICE experiment at CERN makes precise comparison of light nuclei and antinuclei

Related Stories

Protons and antiprotons appear to be true mirror images

August 12, 2015

In a stringent test of a fundamental property of the standard model of particle physics, known as CPT symmetry, researchers from the RIKEN-led BASE collaboration at CERN have made the most precise measurements so far of the ...

Tiny drops of early universe 'perfect' fluid

September 1, 2015

The Relativistic Heavy Ion Collider (RHIC), a particle collider for nuclear physics research at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory, smashes large nuclei together at close to the speed of ...

Recommended for you

Researchers improve qubit lifetime for quantum computers

December 8, 2016

An international team of scientists has succeeded in making further improvements to the lifetime of superconducting quantum circuits. An important prerequisite for the realization of high-performance quantum computers is ...

A nano-roundabout for light

December 8, 2016

Just like in normal road traffic, crossings are indispensable in optical signal processing. In order to avoid collisions, a clear traffic rule is required. A new method has now been developed at TU Wien to provide such a ...

20 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

JVK
1.3 / 5 (15) Sep 21, 2015
Big Bang theorists "... have made precise measurements of particle mass and electric charge that confirm the existence of a fundamental symmetry in nature."

The measurement may or may not be required for serious scientists to link the sun's biological energy to the creation of all life on this planet via the de novo creation of nucleic acids and biophysically constrained RNA-mediated protein folding chemistry and nutrient-dependent DNA repair.

Thus, we are once again reminded that it is important to link measurements from top-down causation to biologically-based cause and effect to avoid being labeled a biologically uninformed theorist.

See for review: http://rsfs.royal...abstract
RayInLv
1.8 / 5 (5) Sep 21, 2015
I have always wondered if anti-matter had anti-gravity (ie repulsive).. This would explain a lot of things.
jlewis
3.5 / 5 (4) Sep 21, 2015
"Experiment confirms A fundamental symmetry in nature." Fixed the headline for you.

I don't think anyone seriously thought that protons and electrons wouldn't be CPT symmetric. There's never been a hint otherwise. However, particles like the K0 and B0 don't abide by it (they violate CP and there's direct evidence of T violation).

But even more fundamentally, neutrinos and W/Z particles don't even respect CP parity,
RealScience
4.7 / 5 (13) Sep 21, 2015
Big Bang theorists "... have made precise measurements...

You are confusing theory and experiment again, JVK.
Making precise measurements is experiment and gives experimental results, which is just a wee bit different from what 'theorists' do.
Protoplasmix
4.6 / 5 (11) Sep 21, 2015
I have always wondered if anti-matter had anti-gravity (ie repulsive)..
Not likely. Mass is a scalar quantity. Antimatter isn't negative energy, so why would it be negative mass? Its temperature (on the absolute scale, K) isn't negative. Neither is its speed or volume -- these are all examples of scalar quantities. Also, a photon is its own antiparticle, and all photons are influenced by gravity (e.g., redshift).
This would explain a lot of things.
Such as?
JVK
1.8 / 5 (10) Sep 21, 2015
Making precise measurements is experiment and gives experimental results...


You are attempting to argue with George FR Ellis.

Scientific method: Defend the integrity of physics
http://www.nature...-1.16535

"The imprimatur of science should be awarded only to a theory that is testable. Only then can we defend science from attack."
docile
Sep 22, 2015
This comment has been removed by a moderator.
Torbjorn_Larsson_OM
4.2 / 5 (15) Sep 22, 2015
Re "the sun's biological energy", a star's irradiation isn't metabolic energy until a cell transforms it thusly. (Say, in photosynthesis by making electrons do work.) More importantly, the science has nothing to do with biology as such. Since the pheromone troll is at it again, posting irrelevancies, I dug up an amusing description by a real biolog, who compares him with the late king of cranks, Davison:

""... partly true ... other things that are just too narrow ... bits that are just plain weird ... Further, what he writes is a particularly pretentious, obfuscatory way of saying what he means — he's trying to obscure rather than explain. ...

He crashes into a thread full of lay people and then lords it over them with his abuse of jargon. ... He's babbling in scientese.

And he just keeps hammering away with his pseudo-scientific pronouncements. ... belligerent pomposity ... [ http://phys.org/n...html#jCp ]
Torbjorn_Larsson_OM
4.1 / 5 (14) Sep 22, 2015
CPT confirmed yet again.

@jlewis: I assume you refer to the Shakarov conditions for matter/antimatter asymmetry of the universe, not the kaon (K0) CP violations? Kaons obey CPT too.

@docile: Atomic orbitals aren't spherical symmetric except in simpler cases. [ https://en.wikipe..._orbital ] The largest structures of the universe, cosmic filaments, are fractal. [ https://en.wikipe...filament ] (The universe itself can be described as spherical symmetric vs its large scale structure of homogeneity and isotropy.)

I don't know what "four zones" refer to. (The 3+1 large scale space+time dimensions? But they aren't "zones".) But the point of the article is that there isn't any CPT violation as of yet, and none expected.
JVK
1.4 / 5 (9) Sep 22, 2015
He's babbling in scientese.


Let's be realistic. What someone else thinks is babbling in scientese may simply be too difficult for them to understand. It does not mean that serious scientists do not understand the language and how it is used to communicate thoughts about the creation of organized genomes.

For example: Your Brain Isn't a Computer. It's a Quantum Field. http://bigthink.c...h-reason

The obvious link from quantum mechanics to quantum Darwinism must be the selection of nutrients and the physiology of reproduction. That's the top-down causation Ellis and others have addressed elsewhere. Because it can be linked from atoms to ecosystems by what is currently known to serious scientists about physics, chemistry, and molecular epigenetics, the serious scientists aren't likely to be found here.

Biologically uninformed science idiots can't understand cause and effect. Instead, they discuss ridiculous theories.
RealScience
4.6 / 5 (11) Sep 22, 2015
Making precise measurements is experiment and gives experimental results...


You are attempting to argue with George FR Ellis.

Scientific method: Defend the integrity of physics
http://www.nature...-1.16535

"The imprimatur of science should be awarded only to a theory that is testable. Only then can we defend science from attack."


JVK, this article is about TESTING a theory that there is a fundamental symmetry between nuclei and anti-nuclei. The theory passed this test.

Compare this to your theory that mutations are never beneficial and thus selected for. Lenski's results are a test of your theory, and Lenski's results show that your theory FAILED. When you 'throw out results that appear to attest to mutations as the cause of adaptive evolution', rather than revising your theory to match the experimental results, you become a failed theorist and a pseudo-scientist.
RealScience
4.7 / 5 (12) Sep 22, 2015
... It does not mean that serious scientists do not understand the language and how it is used to communicate thoughts about the creation of organized genomes.


That's hilarious!
You, JVK, refuse to use the term 'mutations' as it is used by scientists in the fields of biology and genetics, and then you refuse to define what you mean by the term.

LMAO!

Biologically uninformed science idiots can't understand cause and effect. Instead, they discuss ridiculous theories.

That is really funny coming from you, JVK, who endlessly pushes a theory that experimental results have shown to be wrong. If you want to stop being biologically uninformed, JVK, the first step is to stop throwing out experimental results that disagree with your theory.

ROTFLMAO!
Torbjorn_Larsson_OM
4.3 / 5 (12) Sep 23, 2015
"Let's be realistic ... serious scientists ... Biologically uninformed science idiots".

It _was_ used by a serious, well informed scientist about your babbling. Again you show that you can't read, can't write and can't understand science.

You shouldn't use the word "realistic", because it reminds all others that you aren't. The theory of incompetents is a perfect fit on you as an individual (too incompetent to judge their own incompetence); we can assume you are one. How do you tie your shoelaces? Curious minds definitely don't want to know.
charlimopps
3.9 / 5 (11) Sep 23, 2015
JVK, welcome to my ignore list. Best feature on this site.
Captain Stumpy
4.3 / 5 (11) Sep 23, 2015
I dont know if jk is attempting humour and irony or just being blatantly STUPID here:
What someone else thinks is babbling in scientese may simply be too difficult for them to understand. It does not mean that serious scientists do not understand the language and how it is used to communicate thoughts
the irony of this statement is: this is what we've been telling your for at least 2 years! ROTFLMFAO
(see RealScience and Torbjorn_Larsson_OM above)

your problem (jk) is that you DO NOT UNDERSTAND the words you use! then you arbitrarily redefine words but REFUSE to actually give your used definitions!

you babble in techno-scientese when you don't understand what you are saying because of your religion and religious proselytizing issues... this is why you refuse to accept the lexicon of your field and , IN YOUR OWN WORDS, you refuse to accept definitions!

that is the "language and how it is used to communicate" part that you don't use

ROTFLMFAO
EPIC FAILURE!
bschott
2.5 / 5 (4) Sep 24, 2015
"Experiment confirms A fundamental symmetry in nature." Fixed the headline for you.


Did we really need this kind of confirmation? Studying stable "particles" leads to the same conclusion.
verkle
Sep 24, 2015
This comment has been removed by a moderator.
NigelBurke
not rated yet Sep 28, 2015
The Universe might even be 'handed' in the same way as, well, hands. One 'hand' may have mostly matter while the other has mostly anti-matter, and only on the boundary between the two could there be anywhere near equal amounts of each.
I'm afraid someone else will have to do the mathematics, but that's the easy part. Isn't it?
;-)
docile
Sep 28, 2015
This comment has been removed by a moderator.
antialias_physorg
5 / 5 (1) Sep 28, 2015
and only on the boundary between the two could there be anywhere near equal amounts of each

That would be a very violent boundary (i.e. easily visible). No such boundary has yet been observed.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.