Press Releases and News

ATLAS Collaboration: Searching for new physics using asymmetric top-quark events

The ATLAS Collaboration is studying the subtle differences in the energies and directions of top and antitop quarks produced in the LHC. A new analysis, led by MPA Fellow Alexander Basan shows agreement with the Standard Model, allowing to set limits on the influence of potential new particles and interactions. The ATLAS collaboration has published the new results and explained them for laymen in a "Physics Briefing".

Read more about this in the original PRISMA+ news item here

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IceCube analysis puts most general constraints on nonstandard neutrino interactions

Team of scientists of the PRISMA+ Cluster of Excellence lead on new publication

For decades, physicists have theorized that the current best theory describing particle physics—the "Standard Model"—was not sufficient to explain the way the universe works. In the search for physics beyond the Standard Model (BSM), elusive particles called neutrinos might point the way.

Neutrinos are sometimes called "ghost particles" because they so rarely interact with matter that they can travel through just about anything. However, while traveling through matter, they may be "slowed down", depending on the neutrino's type (or "flavor"), in what is known as a "matter effect".

In many BSM models, neutrinos have extra interactions with matter due to new and thus far unknown forces of nature. Different neutrino flavors might be affected to varying extents by these interactions, and the strength of the resulting matter effects depends on the density of matter the neutrinos are passing through. If researchers observe matter effects that can be explained as "nonstandard interactions" (NSI), it might point to new physics.

The IceCube Neutrino Observatory, an array of sensors embedded in the South Pole ice, was built to detect and study neutrinos from outer space. But in IceCube's center is a subset of more densely packed sensors called DeepCore; this region is sensitive to lower energy neutrinos formed in Earth's atmosphere that are potentially more strongly affected by nonstandard matter effects. In a paper published today in Physical Review D, the IceCube Collaboration discusses an analysis in which they examined three years of DeepCore data to see whether atmospheric neutrinos have extra interactions with matter. This analysis puts limits on all the parameters used to describe NSI, an improvement upon earlier analyses that were restricted to only the NSI regimes to which IceCube is most sensitive.

Link to the original PRISMA+ news release here

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Topping-out ceremony for laboratory and office buildings at the future Center for Fundamental Physics (CFP)

Topping-out ceremony for laboratory and office buildings at the future Center for Fundamental Physics of Johannes Gutenberg University Mainz
Above-ground counterpart to the renovation and expansion of the underground experiment halls for the MESA electron accelerator

The new Center for Fundamental Physics (CFP) at Johannes Gutenberg University Mainz (JGU) continues to grow vigorously, both underground and above ground. The topping-out ceremony for the four-story laboratory and office building CFP II has now been celebrated. With several research laboratories, a two-storey assembly hall as well as seminar and conference rooms with a total of around 3,540 square meters, the CFP II forms the aboveground counterpart to the renovation and expansion of the underground experiment halls (CFP I), in which the new MESA electron accelerator will be operated in the future.

The state and federal government are investing around 75 million euros in a high-performance structural environment for cutting-edge research by the federally funded PRISMA + Cluster of Excellence in the field of particle and hadron physics, which deals, for example, with research into dark matter, the properties of which have so far only been inferred indirectly can be. The construction project is being managed by the Mainz branch of the State Office for Real Estate and Construction Management. The handover of the building to JGU is planned for summer 2023.

See more at the press release here

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Common professorship appointment with Fermilab: Alfons Weber becoming member of ETAP

PRISMA+-research programme in neutrino physics further expanded

University Press release

Neutrino research is an important focus of the PRISMA + Cluster of Excellence at Johannes Gutenberg University Mainz (JGU): Mainz researchers are involved in many large-scale international experiments at the South Pole, in Italy and in China. Now, JGU and the Fermilab Prof. Dr. Alfons Weber appointed as the new W3 professor. The proven neutrino expert is moving from the renowned Oxford University to Mainz and will further strengthen the neutrino research program. His focus is on promoting German participation in the next major neutrino experiment, the Deep Underground Neutrino Experiment (DUNE) at the Fermilab near Chicago.
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Solar CNO neutrinos observed for the first time

Characteristic neutrinos are evidence of the secondary fusion process that powers our sun

University Press release

Scientists from the Borexino collaboration have provided the first experimental proof of the occurrence of the so-called CNO cycle in the sun: They were able to directly observe characteristic neutrinos that arise during this fusion process. This is an important milestone towards a complete understanding of the fusion processes in the sun. Even more: While the CNO cycle plays a subordinate role in the sun, it is probably the predominant way of generating energy in stars, which are much heavier and therefore hotter than the sun. The results of the Borexino collaboration are published in the current issue of Nature.
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Surprising Signal in the XENON1T Dark Matter Experiment

Scientists of the PRISMA+ Cluster of Excellence of the Johannes Gutenberg University Mainz significantly involved

University Press release

Scientists from the international XENON collaboration announced today that data from their XENON1T, the world's most sensitive dark matter experiment, show a surprising excess of events. The scientists do not claim to have found dark matter. Instead, they say to have observed an unexpected rate of events, the source of which is not yet fully understood. The signature of the excess is similar to what might result from a tiny residual amount of tritium (super heavy hydrogen), but could also be a sign of something more exciting: the existence of a new particle known as the solar axion or the indication of previously unknown properties of neutrinos.
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From China to the South Pole: Joining forces to solve the neutrino mass puzzle

Study by Mainz physicists indicates that the next generation of neutrino experiments may well find the answer to one of the most pressing issues in neutrino physics

University Press release

Among the most exciting challenges in modern physics is the identification of the neutrino mass ordering. Physicists from the PRISMA+ Cluster of Excellence at Johannes Gutenberg University Mainz (JGU) play a leading role in a new study that indicates that the puzzle of neutrino mass ordering may finally be solved in the next few years – thanks to the combined performance of two new neutrino experiments that are in the pipeline, the upgrade of the IceCube experiment at the South Pole and the Jiangmen Underground Neutrino Observatory (JUNO) in China. They will soon give the physicists access to much more sensitive and complementary data on the neutrino mass ordering.
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Signals from inside the Earth: Borexino Experiment releases new data on geoneutrinos

Exclusive insight into processes and conditions in the Earth's interior

University Press release

Scientists involved in the Borexino Collaboration, among them researches from the PRISMA+ Cluster of Excellence of Johannes Gutenberg University Mainz (JGU), have presented new results for the measurement of neutrinos originating from the interior of the Earth, so called geoneutrinos. These elusive "ghost particles" rarely interact with matter, making their detection difficult. With the newly presented analysis, the researchers have now been able to access 53 events in Borexino, which is almost twice as many as in the previous analysis of the data. The results provide an exclusive insight into processes and conditions in the Earth's interior that remain puzzling to this day.

The Earth is shining, even if it is not at all visible to the naked eye. The reason for this is geoneutrinos, which are produced in radioactive decay processes in the interior of the Earth. Every second, about one million of these elusive particles penetrate every square centimeter of our planet's surface.

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Matthias Schott receives ERC Consolidator Grant for searches for axions

Data from the Large Hadron Collider at CERN can help to find axions

University Press release

Axions are hypothetical elementary particles that physicists initially postulated to solve a theoretical inadequacy of the strong interaction, the so-called strong CP problem. In recent years, however, it has emerged that axions or axion-like particles (ALPs) could also solve other puzzles of modern physics: They are considered promising candidates for dark matter and could also cause the theory-experiment discrepancy for the value of the abnormal magnetic moments of the muon.

This search can now begin: The European Research Council (ERC) supports the project "Search for Axion-Like-Particles at the LHC - Light @ LHC" with an ERC Consolidator Grant for Prof. Dr. Matthias Schott in the amount of more than 1.5 million euros. The project will be realized over the next five years at the PRISMA+ Cluster of Excellence at the Johannes Gutenberg University Mainz.

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