A new observation by the LHCb experiment finds that charm quarks behave differently than their antiparticle counterparts.
The Beacon-News
The Proton Improvement Plan II, known as PIP-II, is a brand new leading-edge superconducting linear accelerator.
Physicists at EPFL propose a new “quantum simulator”: a laser-based device that can be used to study a wide range of quantum systems. Studying it, the researchers have found that photons can behave like magnetic dipoles at temperatures close to absolute zero, following the laws of quantum mechanics. The simple simulator can be used to better understand the properties of complex materials under such extreme conditions.
When subject to the laws of quantum mechanics, systems made of many interacting particles can display behaviour so complex that its quantitative description defies the capabilities of the most powerful computers in the world. In 1981, the visionary physicist Richard Feynman argued we can simulate such complex behavior using an artificial apparatus governed by the very same quantum laws – what has come to be known as a “quantum simulator.”
One example of a complex quantum system is that of magnets placed at really low temperatures. Close to absolute zero (−273.15 degrees Celsius), magnetic materials may undergo what is known as a “quantum phase transition.” Like a conventional phase transition (e.g. ice melting into water, or water evaporating into steam), the system still switches between two states, except that close to the transition point the system manifests quantum entanglement – the most profound feature predicted by quantum mechanics. Studying this phenomenon in real materials is an astoundingly challenging task for experimental physicists.
Why do we exist? This is arguably the most profound question there is and one that may seem completely outside the scope of particle physics.
But our new experiment at CERN’s Large Hadron Collider has taken us a step closer to figuring it out.
To understand why, let’s go back in time some 13.8 billion years to the Big Bang. This event produced equal amounts of the matter you are made of and something called antimatter.
Astronomers observed a ghostly pulsar, a superdense, rapidly spinning neutron star exploded from a supernova 10,000 years ago, racing through space at nearly 2.5 million miles an hour—so fast it could travel the distance between Earth and the Moon in just 6 minutes. The discovery was made using NASA’s Fermi Gamma-ray Space Telescope and the National Science Foundation’s Karl G. Jansky Very Large Array (VLA).
The pulsar lies about 53 light-years from the center of a supernova remnant called CTB 1. Its rapid motion through interstellar gas results in shock waves that produce the tail of magnetic energy and accelerated particles detected at radio wavelengths using the VLA. The tail extends 13 light-years and clearly points back to the center of CTB 1.
This one, dubbed PSR J0002+6216 (J0002 for short), sports a radio-emitting tail pointing directly toward the expanding debris of a recent supernova explosion. “Thanks to its narrow dart-like tail and a fortuitous viewing angle, we can trace this pulsar straight back to its birthplace,” said Frank Schinzel, a scientist at the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico. “Further study of this object will help us better understand how these explosions are able to ‘kick’ neutron stars to such high speed.”
In February, the CMS and MoEDAL collaborations at CERN signed an agreement to hand over to MoEDAL a section of the LHC beam pipe that was located inside CMS between 2008 and 2013. The delicate object, 6 metres long and made of beryllium, will now be sliced and fed into a highly precise magnetic sensors in order to allow MoEDAL to look for magnetic monopoles: hypothetical particles with only a single magnetic pole – north or south – unlike north-south dipoles we are familiar with.
Paul Dirac posited the existence of magnetic monopoles in 1931, and, although never observed, they could be produced in collisions within the LHC. They would not travel very far after being produced, binding with the beryllium nuclei of the beam pipe and remaining there awaiting discovery.
The MoEDAL collaboration will cut the beam pipe at a special facility at the Centre for Particle Physics at the University of Alberta in Canada and ship the pieces back across the Atlantic to ETH Zurich in Switzerland to look for electromagnetic anomalies in them. Many theories attempting to unify all of the known forces into a single force (so-called “Grand Unified Theories”) require the existence of monopoles and finding them could open the door to all-new physics.
Up until now, the ability to make gray goo has been theoretical. However, the scientists at the Columbia University School of Engineering and Applied Science have made a significant breakthrough. The individual components are computationally simple but can exhibit complex behavior.
Current robots are usually self-contained entities made of interdependent subcomponents, each with a specific function. If one part fails, the robot stops working. In robotic swarms, each robot is an independently functioning machine.
In a new study published today in Nature, researchers at Columbia Engineering and MIT Computer Science & Artificial Intelligence Lab (CSAIL), demonstrate for the first time a way to make a robot composed of many loosely coupled components, or “particles.” Unlike swarm or modular robots, each component is simple, and has no individual address or identity. In their system, which the researchers call a “particle robot,” each particle can perform only uniform volumetric oscillations (slightly expanding and contracting), but cannot move independently.
The team, led by Hod Lipson, professor of mechanical engineering at Columbia Engineering, and CSAIL Director Daniela Rus, discovered that when they grouped thousands of these particles together in a “sticky” cluster and made them oscillate in reaction to a light source, the entire particle robot slowly began to move forward, towards the light.
In quantum physics, particles can ’tunnel’ through seemingly impenetrable barriers, even when they apparently don’t have the energy to do so. Now, researchers have gleaned behind the curtain to better understand how this trick is done.
This problem has puzzled scientists for decades – in particular, the time it takes for particles to do their quantum tunnelling, and get from one side of a barrier to another.
In the case of the atomic hydrogen particles used in these experiments, the researchers found that it happens instantaneously.
