Posted in particle physics
The Standard Model is one of the most well-tested theories in particle physics. But scientists are searching for new physics beyond it.
In particle physics, “annihilation” is a transformation.
Building experimental evidence suggests that the electron, muon and tau may feel different forces.
Yesterday, LHCb submitted for publication new results of matter-antimatter oscillations using decays of charm particles, significantly improving the current experimental knowledge!
Read our news: https://lhcb-outreach.web.cern.ch/2022/02/21/high-precision-…ht-mesons/
Today, the LHCb Collaboration submitted for publication a paper that reports the results of the high precision measurement of the charm oscillation (mixing) parameter yCP – yCPKπ using two body D0 meson decays. The result is more precise than the current world average value by a factor of four.
The neutral meson particle-antiparticle systems, Bs0−Bs0, B0–B0, D0–D0 and K0–K0 oscillate (transform into their antiparticle and back) with very different frequencies. The Bs0−Bs0 oscillations are the fastest, about 3 million million times per second (3×1012). The oscillations B0–B0 are about 37 times slower while the oscillations D0–D0 are even slower; the oscillation period is over one hundred times larger than the average lifetime of a D0 meson. Therefore only very few D0 mesons have the time to oscillate before decaying.
The quantum mechanical treatment of neutral charm meson oscillations leads to two neutral mesons, D1 and D2, each with their own mass, m1 and m2, and typical lifetime represented by their decay width, Γ1 and Γ2. The D0-D0 oscillations are described by the two dimensionless parameters, x=(m1-m2)/Γ, determining the frequency of oscillations, and y=(Γ1-Γ2)/Γ, in which Γ is the average width, (Γ1+Γ2)/2.
Our spatial sense doesn’t extend beyond the familiar three dimensions, but that doesn’t stop scientists from playing with whatever lies beyond.
Rice University physicists are pushing spatial boundaries in new experiments. They’ve learned to control electrons in gigantic Rydberg atoms with such precision they can create “synthetic dimensions,” important tools for quantum simulations.
The Rice team developed a technique to engineer the Rydberg states of ultracold strontium atoms by applying resonant microwave electric fields to couple many states together. A Rydberg state occurs when one electron in the atom is energetically bumped up to a highly excited state, supersizing its orbit to make the atom thousands of times larger than normal.
Ion channels are crucial for neural communication; they control the flow and gradient of charged particles, creating electrical signals. Recent work report | Neuroscience.
In this study, the researchers assessed how dense ion channels were packed in the membranes of neuronal cells from ten species of mammals, including mice, rats, rabbits, ferrets, macaques, marmosets, macaques, humans, and one of the smallest known mammals, an animal called the Etruscan shrew. The team focused on a type of excitatory neuron typically found in the cortex of the brain, and three ion channels that are in the membranes of those cells; two are voltage-gated ion channels that control the movement of potassium, another is called the HCN channel and both potassium and sodium ions can flow through it.
Studies have suggested that the human brain is built like the brains of other mammals, said first study author Lou Beaulieu-Laroche, a former MIT graduate student. It was once thought that in mammals, these channels would be present at about the same density from one species to another.
Instead, the researchers determined that as the neurons got bigger, the density of ion channels increased. That was a notable finding, because as that density increases, more energy needed to move ions in and out of neurons, explained senior study author Mark Harnett, an associate professor of brain and cognitive sciences at MIT.
For centuries, people have dreamed of being driven at speed across the vast oceans of space by winds of light.
As whimsical as the idea sounds, nudging reflective sails slowly towards the speed of light using nothing more than the punch of photons might be our only plausible shot at reaching another star inside of a single human lifetime.
It’s also far easier said than done. Particles of light might be fast, but they don’t push very hard. If you make a sail light enough to feel the inertia of radiation, then the constant barrage of photons could inadvertently damage its material.
The detection of cosmic rays is rare – however the latest detection is even rarer as it appears to be going in the wrong direction.
Cosmic rays are bombarding the Earth every day and are measured at observing sites across the world, with the most notable being located at the Earths south pole.
Not to be fooled by their historical name, cosmic rays generally refer to high energy particles with mass whereas high energy in the form of gamma rays and/or X-rays are photons. These cosmic particles were discovered in 1912 by Victor Hess when he ascended to 5,300 meters above sea level in a hot air balloon and detected significantly increased levels of ionization in the atmosphere.
Thank you to Wren for supporting PBS. To learn more, go to https://wren.co/start/spacetime.
PBS Member Stations rely on viewers like you. To support your local station, go to: http://to.pbs.org/DonateSPACE
Sign Up on Patreon to get access to the Space Time Discord!
https://www.patreon.com/pbsspacetime.
Objective Collapse Theories offer a explanation of quantum mechanics that is at once brand new and based in classical mechanics. In the world of quantum mechanics, it’s no big deal for particles to be in multiple different states at the same time, or to teleport between locations, or to influence each other faster than light. But somehow, none of this strangeness makes its way to the familiar scale of human beings — even though our world is made entirely of quantum-weird building blocks. The explanations of this transition range from the mystical influence of the conscious mind to the grandiose proposition of multiple realities. But Objective Collapse Theories feels as down to earth as the classical world that we’re trying to explain. Let’s see if it makes any sense.
Check out the Space Time Merch Store.
https://www.pbsspacetime.com/shop.
Sign up for the mailing list to get episode notifications and hear special announcements!
Physicists have predicted the existence of dark matter, a material that does not absorb, emit or reflect light, for decades. While there is now significant evidence hinting to the existence of dark matter in the universe, as it was never directed detected before its composition remains unknown.
In recent years, researchers worldwide have made different hypotheses about the composition of this elusive material and tried to test them experimentally. Many have suggested that it could be comprised of new and previously unobserved types of elementary particles, such as axions and weakly interactive massive particles (WIMPs).
A few weeks ago, two large research collaborations, the PandaX-4T and the ADMX Collaborations, published the results of two new dark matter searches based on different hypothesis. In their study, featured in Physical Review Letters, the PandaX-4T Collaboration tried searching for signs of a new elementary particle in data collected using a time projection chamber at the China Jinping Underground Laboratory (CJPL), the deepest underground lab in world.
The world’s most precise atomic clock has confirmed that the time dilation predicted by Albert Einstein’s theory of general relativity works on the scale of millimetres.
Physicists have been unable to unite quantum mechanics – a theory that describes matter at the smallest scales – with general relativity, which predicts the behaviour of objects at the largest cosmic scales, including how gravity bends space-time. Because gravity is weak over small distances, it is hard to measure relativity on small scales.
But atomic clocks, which count seconds by measuring the frequency of radiation emitted when electrons around an atom change energy states, can detect these minute gravitational effects.
Decaying isotopes of hydrogen have just given us the smallest measurement yet of the mass of a neutrino.
By measuring the energy distribution of electrons released during the beta decay of tritium, physicists have determined that the upper limit for the mass of the electron antineutrino is just 0.8 electronvolts. That’s 1.6 × 10–36 kilograms in metric mass, and very, very freaking small in imperial.
Although we still don’t have a precise measurement, narrowing it down brings us closer to understanding these strange particles, the role they play in the Universe, and the impact they could have on our current theories of physics. The achievement was made at the Karlsruhe Tritium Neutrino Experiment (KATRIN) in Germany.
