Lifeboat Foundation

A hint of the possible existence of a hypothetical particle called a leptoquark has appeared as an unexpected difference in how beauty quarks decay to create electrons or muons. Measured by physicists working on the LHCb experiment on the Large Hadron Collider (LHC) at CERN, the difference appears to violate the principle of “lepton universality”, which is part of the Standard Model of particle physics. The measurement has been made at a statistical significance of 3.1σ, which is well below the 5σ level that is usually considered a discovery. If the violation is confirmed, it could provide physicists with important clues about physics beyond the Standard Model – such as the existence of leptoquarks.

When high-energy protons are smashed together at the LHC large numbers of exotic particles are created, including some containing the beauty quark. These exotic particles quickly decay, and beauty quarks can follow decay paths that involve the production of either electrons or muons, which are both leptons. According to the Standard Model of particle physics, the interactions involved in producing leptons do not discriminate between lepton type, so the rates at which electrons and muons are created by beauty-quark decays are expected to be the same.

Starting in 2014, physicists working on LHCb noticed hints of the violation of this lepton universality. Now, after analysing collision data collected between 2011 and 2018, the researchers have found that the beauty quark appears to favour the electron decay chain over the muon decay chain.

For 50 years, the research community has been hunting unsuccessfully for the so-called Odderon particle. Now, a Swedish-Hungarian research group has discovered the mythical particle with the help of extensive analysis of experimental data from the Large Hadron Collider at CERN in Switzerland.

In 1973, two French particle physicists found that, according to their calculations, there was a previously unknown quasi-particle. The discovery sparked an international hunt.

The Odderon particle is what briefly forms when protons collide in high-energy collisions, and in some cases do not shatter, but bounce off one another and scatter. Protons are made up of quarks and gluons, that briefly form Odderon and Pomeron particles.

In this work, we carry out KS-MD simulations for a range of elements, temperatures, and densities, allowing for a systematic comparison of three RPP models. While multiple RPP models can be selected, ^7–11 7. J. Vorberger and D. Gericke, “Effective ion–ion potentials in warm dense matter,” High Energy Density Phys. 9, 178 (2013). https://doi.org/10.1016/j.hedp.2012.12.009 8. Y. Hou, J. Dai, D. Kang, W. Ma, and J. Yuan, “Equations of state and transport properties of mixtures in the warm dense regime,” Phys. Plasmas 22, 022711 (2015). https://doi.org/10.1063/1.4913424 9. K. Wünsch, J. Vorberger, and D. Gericke, “Ion structure in warm dense matter: Benchmarking solutions of hypernetted-chain equations by first-principle simulations,” Phys. Rev. E 79, 010201 (2009). https://doi.org/10.1103/PhysRevE.79.010201 10. L. Stanton and M. Murillo, “Unified description of linear screening in dense plasmas,” Phys. Rev. E 91, 033104 (2015). https://doi.org/10.1103/PhysRevE.91.033104 11. W. Wilson, L. Haggmark, and J. Biersack, “Calculations of nuclear stopping, ranges, and straggling in the low-energy region,” Phys. Rev. B 15, 2458 (1977). https://doi.org/10.1103/PhysRevB.15.2458 we choose to compare the widely used Yukawa potential, which accounts for screening by linearly perturbing around a uniform density in the long-wavelength (Thomas–Fermi) limit, a potential constructed from a neutral pseudo-atom (NPA) approach, ^12–15 12. L. Harbour, M. Dharma-wardana, D. D. Klug, and L. J. Lewis, “Pair potentials for warm dense matter and their application to x-ray Thomson scattering in aluminum and beryllium,” Phys. Rev. E 94, 053211 (2016). https://doi.org/10.1103/PhysRevE.94.053211 13. M. Dharma-wardana, “Electron-ion and ion-ion potentials for modeling warm dense matter: Applications to laser-heated or shock-compressed Al and Si,” Phys. Rev. E 86, 036407 (2012). https://doi.org/10.1103/PhysRevE.86.036407 14. F. Perrot and M. Dharma-Wardana, “Equation of state and transport properties of an interacting multispecies plasma: Application to a multiply ionized al plasma,” Phys. Rev. E 52, 5352 (1995). https://doi.org/10.1103/PhysRevE.52.5352 15. L. Harbour, G. Förster, M. Dharma-wardana, and L. J. Lewis, “Ion-ion dynamic structure factor, acoustic modes, and equation of state of two-temperature warm dense aluminum,” Phys. Rev. E 97, 043210 (2018). https://doi.org/10.1103/PhysRevE.97.043210 and the optimal force-matched RPP that is constructed directly from KS-MD simulation data.

Each of the models we chose impacts our physics understanding and has clear computational consequences. For example, success of the Yukawa model reveals the insensitivity to choices in the pseudopotential and screening function and allows for the largest-scale simulations. Large improvements are expected from the NPA model, which makes many fewer assumptions with a modest cost of pre-computing and tabulating forces. (See the Appendix for more details on the NPA model.) The force-matched RPP requires KS-MD data and is therefore the most expensive to produce, but it reveals the limitations of RPPs themselves since they are by definition the optimal RPP.

Using multiple metrics of comparison between RPP-MD and KS-MD including the relative force error, ion–ion equilibrium radial distribution function g (r), Einstein frequency, power spectrum, and the self-diffusion transport coefficient, the accuracy of each RPP model is analyzed. By simulating disparate elements, namely, an alkali metal, multiple transition metals, a halogen, a nonmetal, and a noble gas, we see that force-matched RPPs are valid for simulating dense plasmas at temperatures above fractions of an eV and beyond. We find that for all cases except for low temperature carbon, force-matched RPPs accurately describe the results obtained from KS-MD to within a few percent. By contrast, the Yukawa model appears to systematically fail at describing results from KS-MD at low temperatures for the conditions studied here validating the need for alternate models such as force-matching and NPA approaches at these conditions.

It’s another step on the road to developing quantum information processing applications: A key experiment succeeded in going beyond the previously defined limits for photon applications. Anahita Khodadad Kashi and Prof. Dr. Michael Kues from the Institute of Photonics and the Cluster of Excellence PhoenixD at Leibniz University Hannover (Germany) have demonstrated a novel interference effect. The scientists have thus shown that new color-coded photonic networks can be tapped, and the number of photons involved can be scaled. “This discovery could enable new benchmarks in quantum communication, computational operations of quantum computers as well as quantum measurement techniques and is feasible with existing optical telecommunication infrastructure,” says Kues.

The decisive experiment was successfully performed in the newly established Quantum Photonics Laboratory (QPL) of the Institute of Photonics and the Hannover Centre for Optical Technologies at Leibniz University Hannover. Anahita Khodadad Kashi succeeded in quantum-mechanically interfering independently generated pure photons with different colors, i.e., frequencies. Khodadad Kashi detected a so-called Hong-Ou-Mandel effect.

Hong-Ou-Mandel interference is a fundamental effect of quantum optics that forms the basis for many quantum information processing applications—from quantum computing to quantum metrology. The effect describes how two photons behave when they collide on a spatial beam splitter and explains the phenomenon of quantum mechanical interference.

One of the biggest challenges will be to create superpositions of diamonds that can remain stable over distances of a meter. More than four years ago researchers at Stanford University managed to separate a superposition consisting of 10000 atoms by about half a meter—the current record. “But we’re talking about doing it with diamonds that would have a billion or 10 billion atoms, and that is way more difficult,” Mazumdar says.

Many of the other technologies needed for the device—high vacuums, ultralow temperatures, precisely controlled magnetic fields—have all been achieved separately by various groups. But bringing them together will not be easy. “Just because you can juggle and ride a bike doesn’t mean you can do both at once,” Morley says.

If the device is ever built, it could transform gravitational-wave astronomy. The world’s current gravitational-wave detectors are all firmly anchored to the ground. “The only orientation LIGO can have is due to Earth’s rotation,” Bose says. A small detector such as MIMAC, on the other hand, could be pointed at any direction in the sky. And any physics lab in the world could house it. “The challenge is to get one of them working,” Bose says. “If one of them works, it would be very easy to make several more.”

A particle shower detected by the IceCube Neutrino Observatory at the very high energy of the Glashow resonance demonstrates its potential for the study of high-energy particle physics and astrophysics.

In my last post, I talked about the idea of warp drive and whether it might one day be possible. Today I’ll talk about another faster-than-light trick: wormholes.

Wormholes are an old idea in general relativity. It’s based on work by Albert Einstein and Nathan Rosen, who tried to figure out how elementary particles might behave in curved spacetime. Their idea treated particle-antiparticle pairs as two ends of a spacetime tube.

This Einstein-Rosen Bridge would look like a black hole on one end, and an anti-black hole, or white hole, on the other end.

At microscopic scales, picking, placing, collecting, and arranging objects is a persistent challenge. Advances in nanotechnology mean that there are ever more complex things we’d like to build at those sizes, but tools for moving their component parts are lacking.

Now, new research from the University of Pennsylvania’s School of Engineering and Applied Science shows how simple, microscopic robots, remotely driven by magnetic fields, can use capillary forces to manipulate objects floating at an oil-water interface.

This system was demonstrated in a study published in the journal Applied Physics Letters on January 28, 2020.

A new type of maser made from periodically driven xenon atoms can detect low frequency magnetic fields far better than any previous magnetometer, according to scientists in China and Germany. The researchers believe their device is ready for use in a proposed gravitational wave search and might in future be used to find hypothetical dark matter particles.

Masers are the microwave-wavelength equivalent of lasers and their extreme frequency stability allows them to make invaluable contributions to atomic clocks, radio telescopes and several other areas of physics. In a traditional maser – as in a traditional laser – the masing action occurs between two energy levels in an atomic or molecular gain medium confined in a cavity. As electromagnetic radiation bounces back and forth in the cavity, photons whose frequency is resonant with the energy difference between the two levels are repeatedly emitted and absorbed by the atoms. Eventually, a “population inversion” with more atoms in the upper level is achieved, and stimulated emission from these atoms produces a highly monochromatic beam of microwave radiation.