EPJ Plus Highlight - On the trail of the Higgs Boson

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Published on 05 December 2018

The elusive particle won't share all the secrets of its creation mechanism at once

For the physics community, the discovery of new particles like the Higgs Boson has paved the way for a host of exciting potential experiments. Yet, when it comes to such an elusive particle as the Higgs Boson, it's not easy to unlock the secrets of the mechanism that led to its creation. The experiments designed to detect the Higgs Boson involve colliding particles with sufficiently high energy head-on after accelerating them in the Large Hadron Collider (LHC) at CERN in Geneva, Switzerland. In a quest to understand the production mechanisms for the Higgs Boson, Silvia Biondi from the National Institute of Nuclear Physics, Bologna, Italy investigated the traces of a rare process, called ttH, in which the Higgs Boson is produced in association with a pair of elementary particles referred to as top quarks. Her findings can be found in a recent study published in EPJ Plus. Future LHC experiments are expected to yield even more precise measurements of the Higgs Boson's ability to couple with particles that physicists are already familiar with.

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EPJ A Highlight - The P2-Experiment - A future high-precision measurement of the weak mixing angle at low momentum transfer

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Published on 30 November 2018

The P2-experiment at the new electron accelerator MESA in Mainz aims at a high-precision determination of the weak mixing angle at the permille level at low Q². This accuracy is comparable to existing measurements at the Z-pole but allows for sensitive tests of the Standard Model up to a mass scale of 50 TeV. The weak mixing angle will be extracted from a measurement of the parity violating asymmetry in elastic electron-proton scattering. The asymmetry measured at P2 is smaller than any asymmetry measured so far in electron scattering, with an unprecedented accuracy. This review just published in EPJ A describes the underlying physics and the innovative experimental techniques, such as the Cherenkov detector, beam control, polarimetry, and the construction of a novel liquid hydrogen high-power target. The physics program of the MESA facility comprises indirect, high-precision search for physics beyond the Standard Model, measurement of the neutron distribution in nuclei, transverse single-spin asymmetries, and a possible future extension to the measurement of hadronic parity violation.

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EPJ Plus Focus Point on Modern Astronomy: Selected Issues in Nuclear and High Energy Astrophysics

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Published on 27 November 2018

Modern Astronomy is a multidisciplinary science that evolved widely with respect to old traditional and romantic discipline made at a telescope, observing stars and taking notes of their movements in the sky. Nowadays, high-resolution stellar spectra from gigantic reflectors like VLT, images of planets and distant galaxies made at infrared wavelengths where cool matter or redshifted objects are best seen, high-definition maps of galaxies and the cosmos provided by space-borne telescopes are invaluable sources of data. However, they give us only a partial vision of the universe, which, to be studied and understood, needs to be scrutinized not only in the electromagnetic spectrum but also through probes of different nature, such as high energy particles (cosmic rays) accelerated by Galactic mechanisms, neutrinos from nuclear processes and gravitational waves from space-time perturbations. In this much broader picture, "classical" astronomers, stellar physicists, experts of nucleosynthesis, nuclear and particle physicists and geochemists work together to study the universe and understand its formation and evolution. Since many experts in different fields are needed to undertake this arduous task, it is crucial that the training of young researchers be focused both on providing them with a general physical background, and on specializing them in some specific field among those mentioned.

This focus point aims to give the students and general readers an overview on the state of the art of modern research in stellar modelling and nucleosynthesis, in Gamma- and X-ray astronomy, in astro-particle physics, and in experimental low-energy nuclear astrophysics.

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