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Category: particle physics – Page 32

We investigate the properties of a quantum walk which can simulate the behavior of a spin 1/2 particle in a model with an ordinary spatial dimension, and one extra dimension with warped geometry between two branes. Such a setup constitutes a \(1+1\) dimensional version of the Randall–Sundrum model, which plays an important role in high energy physics. In the continuum spacetime limit, the quantum walk reproduces the Dirac equation corresponding to the model, which allows to anticipate some of the properties that can be reproduced by the quantum walk. In particular, we observe that the probability distribution becomes, at large time steps, concentrated near the “low energy” brane, and can be approximated as the lowest eigenstate of the continuum Hamiltonian that is compatible with the symmetries of the model. In this way, we obtain a localization effect whose strength is controlled by a warp coefficient. In other words, here localization arises from the geometry of the model, at variance with the usual effect that is originated from random irregularities, as in Anderson localization. In summary, we establish an interesting correspondence between a high energy physics model and localization in quantum walks.

Anglés-Castillo, A., Pérez, A. A quantum walk simulation of extra dimensions with warped geometry. Sci Rep 12, 1926 (2022). https://doi.org/10.1038/s41598-022-05673-2

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Over a decade after its discovery, the Higgs boson, often referred to as the “God particle,” continues to captivate physicists and deepen our understanding of the universe. Recent findings from the Max Planck Institute promise to unravel even more about this enigmatic particle, potentially opening doors to uncharted realms of particle physics.

The Higgs boson is a cornerstone of the Standard Model of particle physics, responsible for answering one of the universe’s most fundamental questions: how do particles gain mass? This phenomenon hinges on the Higgs field, an invisible energy field that permeates the cosmos. To visualize this, imagine wading through a pool filled with water versus thick foam. While water might let you glide, the foam slows you down—this interaction mirrors how particles gain mass as they traverse the Higgs field. Without it, the building blocks of matter as we know them couldn’t exist.

Why Understanding Higgs Interactions Matters?

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Advances in inertial confinement fusion and innovative modeling have brought nuclear fusion closer to reality, offering insights into high-energy-density physics and the early universe.

The pursuit of controlled nuclear fusion as a source of clean, abundant energy is moving closer to realization, thanks to advancements in inertial confinement fusion (ICF). This method involves igniting deuterium-tritium (DT) fuel by subjecting it to extreme temperatures and pressures during a precisely engineered implosion process.

In DT fusion, most of the released energy is carried by neutrons, which can be harnessed for electricity generation. Simultaneously, alpha particles remain trapped within the fuel, where they drive further fusion reactions. When the energy deposited by these alpha particles surpasses the energy input from the implosion, the plasma enters a self-sustaining “burning” phase. This significantly boosts energy output and density.

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The wave-particle duality was demonstrated not only with electrons, but when it came to atoms and even molecules, things got complicated. Electrons are 1,800 times lighter than the lightest atom (something discovered by Thomson’s father J.J. Thomson) so they can more easily diffract through the lattice of a crystal.

Atom diffraction had so far been seen in reflection. The atoms were bounced off a surface that was etched to have a grating. The lines don’t need to be as thin as 10,000 times smaller than a hair, like the most important machine you’ve never heard of makes them. Grids with much larger lines, which could have been made in the 1930s, were enough to showcase this phenomenon. However, researchers haven’t been able to show the diffraction of atoms through a crystal until now.

In a yet-to-be-peer-reviewed paper, Carina Kanitz and colleagues from the Institute of Quantum Technologies and the University of Vienna demonstrated diffractions of hydrogen and helium atoms using a one-atom-thick sheet of graphene. The atoms are shot perpendicularly at the graphene sheet at high energy. This should damage the crystal but it doesn’t, and it’s the secret of this successful experiment.

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A new study explores tetraquarks, predicts new exotic particles, and offers deeper insights into their complex structure and behavior.

A new study offers significant advancements in the understanding of tetraquarks — a rare and complex type of particle.

By developing a new approach that combines advanced mathematical methods with a simpler model of how particles interact, the researchers have made important discoveries about the inner structure and mass of these particles.

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Scientists at the Large Hadron Collider (CERN), the world’s most powerful elementary particle booster, have discovered the heaviest form of antimatter ever observed. This discovery is as significant as previous achievements at CERN, in particular the discovery of the Higgs boson and studies of B-meson decay.

The ALICE (A Large Ion Collider Experiment) has discovered an antimatter particle, antihyperhelium-4. It is the “evil twin” of another exotic particle, hyperhelium-4. This form of antimatter consists of two antiprotons, an antineutron, and an unstable antilambda particle, which in turn contains quarks.

The discovery is important for studying the extreme conditions that reigned in the Universe less than a second after the Big Bang. It also helps us understand one of the biggest mysteries of physics, the problem of baryonic asymmetry. According to the theory, matter and antimatter should have existed in equal amounts after the Big Bang, and the mutual annihilation of these particles should have produced pure energy. However, the present Universe is composed predominantly of matter, and antimatter is preserved only in small quantities. The study of hyperhelium and its antiparticle may shed light on the causes of this imbalance.

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Every second, 60 billion neutrinos pass through your thumbnail from the Sun alone!

Neutrino Detectors and the Pacific Ocean Experiment

In the search to understand the cosmos, neutrinos—subatomic particles created in nuclear reactions—have become critical clues to some of physics’ most complex questions. Produced in vast quantities by processes such as nuclear fusion in the Sun, neutrinos are hard to capture due to their weak interactions with matter. On Earth, advanced detectors have been built to study them, including Japan’s Kamiokande and the IceCube Neutrino Observatory in Antarctica. Now, astronomers are setting their sights on a new frontier for neutrino observation: the depths of the Pacific Ocean.

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When quantum electrodynamics, the quantum field theory of electrons and photons, was being developed after World War II, one of the major challenges for theorists was calculating a value for the Lamb shift, the energy of a photon resulting from an electron transitioning from one hydrogen hyperfine energy level to another.

The effect was first detected by Willis Lamb and Robert Retherford in 1947, with the emitted photon having a frequency of 1,000 megahertz, corresponding to a photon wavelength of 30 cm and an energy of 4 millionths of an electronvolt—right on the lower edge of the microwave spectrum. It came when the one electron of the hydrogen atom transitioned from the 2P1/2 energy level to the 2S1/2 level. (The leftmost number is the principal quantum number, much like the discrete but increasing circular orbits of the Bohr atom.)

Conventional quantum mechanics didn’t have such transitions, and Dirac’s relativistic Schrödinger equation (naturally called the Dirac equation) did not have such a hyperfine transition either, because the shift is a consequence of interactions with the vacuum, and Dirac’s vacuum was a “sea” that did not interact with real particles.

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