Nav: Home

Researchers discover CP violation in charm meson decays

April 05, 2019

Researchers from the Higher School of Economics and Yandex, as part of the LHCb collaboration at CERN, have been the first to discover CP violation in charm meson decays. On March 21, representatives of the LHCb collaboration spoke about this recent breakthrough at the Conference on Electroweak Interactions and Unified Theories in La Thuile.

This discovery may become a key to solving the mystery of matter-antimatter asymmetry in the universe.

One of the unsolved problems in physics concerns the abundance of matter over antimatter in the universe. During the first split seconds after the Big Bang, matter and antimatter appeared in equal shares. Today, the observed quantity of antimatter in the universe around us is negligibly small. The physicists are trying to understand where it has gone. According to Soviet academician Andrey Sakharov's hypothesis from 1967, the matter-antimatter imbalance could have evolved as a result of CP invariance violation (particle-antiparticle symmetry).

In 1973, Makoto Kobayashi and Toshihide Maskawa proposed that a natural explanation for CP violation effect. According to the Kobayashi-Maskawa theory, in the Standard Model of fundamental interaction, CP violation happens through a single phase. However, the manifestation of this effect in the decay of particles containing various heavy quarks strongly depends on the other features of the Standard Model of elementary particles. CP violation in charm D meson decays was expected to come to around 0.1-0.01%.

The LHCb (Large Hadron Collider beauty) experiment was carried out at CERN to study B mesons, unstable particles, in the decay of which the matter-antimatter asymmetry manifests particularly well. Scholars analyzed the data received in an LHCb experiment in 2011-2018 and found that the total number of decays of anti-D0 mesons exceeded the total number of decays of D0 mesons. The result has a statistical significance of 5.3 standard deviations, exceeding the threshold of five standard deviations used by particle physicists to claim a discovery.

'Studying CP violation is extremely important for understanding the mechanisms of our universe's evolution,' explained Denis Derkach, Senior Research Fellow at the Faculty of Computer Science Laboratory of Methods for Big Data Analysis (LAMBDA), adding: 'The discovery of CP violation in charm meson decays is a big step in the study of this phenomenon in heavy meson decays'.

Furthermore, researchers from HSE and Yandex School of Data Analysis applied AI tools in the study, which improved the quality of LHCb experiment data selection and analysis. Yandex's computation capacities have also been used to model the LHCb experiment events, which is essential for correct interpretation of the physical results.

'Thanks to our team efforts, the effectiveness of the trigger used to select significant events was increased by 40% on average,' said Fedor Ratnikov, Senior Research Fellow at LAMBDA Laboratory. He noted: 'With the use of neural network Bayesian approaches, we have improved the algorithm for detecting the type of particles observed by the detector. We have also developed a "smart" system for quality monitoring of detector operations'.

National Research University Higher School of Economics

Related Universe Articles:

The largest virtual Universe ever simulated
Researchers from the University of Zurich have simulated the formation of our entire Universe with a large supercomputer.
Does the universe have a rest frame?
Physics is sometimes closer to philosophy when it comes to understanding the universe.
Ancient signals from the early universe
For the first time, theoretical physicists from the University of Basel have calculated the signal of specific gravitational wave sources that emerged fractions of a second after the Big Bang.
Big data for the universe
Astronomers at Lomonosov Moscow State University in cooperation with their French colleagues and with the help of citizen scientists have released 'The Reference Catalog of galaxy SEDs,' which contains value-added information about 800,000 galaxies.
The universe is expanding at an accelerating rate -- or is it?
Five years ago, the Nobel Prize in Physics was awarded to three astronomers for their discovery, in the late 1990s, that the universe is expanding at an accelerating pace.
Visualizing the universe
Computer scientists from the University of Utah will be working with researchers from New York University's Tandon School of Engineering and the American Museum of Natural History (AMNH) to develop OpenSpace, an open-source 3-D software for visualizing NASA astrophysics, heliophysics, planetary science and Earth science missions for planetariums and other immersive environments.
Insights into the dawn of the universe
What did the universe look like just after the Big Bang?
Exploring the mathematical universe
A team of more than 80 mathematicians from 12 countries has begun charting the terrain of rich, new mathematical worlds, and sharing their discoveries on the Web.
The expansion of the universe simulated
The universe is constantly expanding. But how does our universe evolve?
Multilingual Universe from 'Mitaka'
The door to the digital Universe has been flung open!

Related Universe Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#SB2 2019 Science Birthday Minisode: Mary Golda Ross
Our second annual Science Birthday is here, and this year we celebrate the wonderful Mary Golda Ross, born 9 August 1908. She died in 2008 at age 99, but left a lasting mark on the science of rocketry and space exploration as an early woman in engineering, and one of the first Native Americans in engineering. Join Rachelle and Bethany for this very special birthday minisode celebrating Mary and her achievements. Thanks to our Patreons who make this show possible! Read more about Mary G. Ross: Interview with Mary Ross on Lash Publications International, by Laurel Sheppard Meet Mary Golda...