Physicists publish observation of the 'Charming Socialites'

Dec 20, 2013
The decay of the D*+ into a D0 and a soft (low-momentum) pion. The D0 then decays into a negative kaon and a positive pion. This is called a right-sign decay. Another decay mode called a wrong-sign, which is very rare, can occur. In this mode, the D0 decays into a positive kaon and a negative pion. Credit: Paul Karchin, Wayne State University

Protons and neutrons, the particles in an atomic nucleus, are made of smaller pieces called "quarks." Some types of quarks can form particles that exhibit surprising behaviors. Mark Mattson, Ph.D., assistant professor-research, and Paul Karchin, Ph.D., professor, from Wayne State University's Department of Physics and Astronomy in the College of Liberal Arts and Sciences, led a large collaborative effort of physicists at the Fermi National Accelerator Laboratory (Fermilab) in Illinois reporting a bizarre "social" behavior of particles containing "charm" quarks: an observation of "charm mixing."

The result was published this month in Physical Review Letters, the highly-regarded journal for particle physics.

Since the discovery of the charm quark in 1974, physicists have postulated a rare process in which a charm particle spontaneously changes into its antiparticle. Evidence for this unique behavior was uncovered more than three decades later by experiments in the US and Japan. However, conclusive observation did not emerge until this year from the CERN laboratory in Switzerland and Fermilab in the U.S.

Mattson and Karchin worked closely with team co-leaders from Fermilab and the University of Siena in Italy. Robert Harr, Ph.D. and Alexey Petrov, Ph.D., professors of physics and astronomy at Wayne State, served as team advisors.

The ratio of the rare D0 decay mode (K+pi-) to a more common one (K-pi+) versus decay time, measured in units of the D0 lifetime. If the mixing process did not occur, the ratio would remain unchanged with time. The measured ratio includes decays from prompt and non-prompt D0 mesons (blue curve). The ratio using only prompt decays is shown by the red curve. Credit: Paul Karchin, Wayne State University

The charm mixing that has been observed could be due solely to known but may also indicate the presence of previously undiscovered particles and force carriers. Future measurements with improved precision and refined theoretical interpretation may elucidate the puzzle of why particle matter in the universe overwhelmingly dominates over antimatter.

Explore further: Lightweight membrane can significantly reduce in-flight aircraft noise

Related Stories

Particle oddball surprises physicists

Mar 18, 2009

(PhysOrg.com) -- Scientists of the CDF experiment at the Department of Energy's Fermi National Accelerator Laboratory announced yesterday that they have found evidence of an unexpected particle whose curious ...

12 matter particles suffice in nature

Dec 13, 2012

How many matter particles exist in nature? Particle physicists have been dealing with this question for a long time. The 12 matter particles contained in the standard model of particle physics? Or are there ...

Belle discovers new heavy 'exotic hadrons'

Jan 10, 2012

(PhysOrg.com) -- Two unexpected new hadrons containing bottom quarks have been discovered by the Belle Experiment using the High Energy Accelerator Research Organization (KEK)'s B Factory (KEKB), a highly-luminous, ...

Recommended for you

Thinner capsules yield faster implosions

8 hours ago

In National Ignition Facility (NIF) inertial confinement fusion (ICF) experiments, the fusion fuel implodes at a high speed in reaction to the rapid ablation, or blow-off, of the outer layers of the target ...

Direct visualization of magnetoelectric domains

10 hours ago

A novel microscopy technique called magnetoelectric force microscopy (MeFM) was developed to detect the local cross-coupling between magnetic and electric dipoles. Combined experimental observation and theoretical ...

Upside down and inside out

12 hours ago

Researchers have captured the first 3D video of a living algal embryo turning itself inside out, from a sphere to a mushroom shape and back again. The results could help unravel the mechanical processes at ...

Heat makes electrons spin in magnetic superconductors

Apr 24, 2015

Physicists have shown how heat can be exploited for controlling magnetic properties of matter. The finding helps in the development of more efficient mass memories. The result was published yesterday in Physical Review Le ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

davidivad
5 / 5 (2) Dec 20, 2013
proof that the discovery of the higgs is not the end of particle physics by any means.

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.