Tag Archives: exotic

CERN Physicists Discover New Exotic Particles: Key Breakthrough in Particle Physics

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Physicists have made significant advancements with the ATLAS Collaboration at CERN’s Large Hadron Collider (LHC), observing the excited state of the Bc*+ Meson. This unique meson consists of a charm quark paired with a bottom antiquark.

Bc*+ Artist’s impression of the meson. Image credit: Daniel Dominguez / CERN.

Protons and neutrons, fundamental components of matter, belong to a larger class of particles known as hadrons. Hadrons are composite particles formed from quarks held together by the strong force.

These particles are classified into two main groups: baryons, which are composed of three quarks (e.g., protons and neutrons), and mesons, which consist of a quark-antiquark pair.

Despite years of research, many phenomena associated with the strong force still remain elusive, particularly the interactions among quarks in hadrons.

Heavy quark mesons, such as those containing charm and bottom quarks, serve as essential testbeds for evaluating theoretical models regarding these interactions.

Particularly noteworthy is the Bc+ meson, which contains both charm quarks and bottom antiquarks.

ATLAS physicists created an excited form of the Bc+ meson through high-energy proton-proton collisions at the LHC.

Following these collisions, the Bc*+ quickly decays into Bc+ mesons accompanied by photons.

Detecting these photons, along with the decay products of Bc+, provides critical evidence confirming the existence of the Bc*+ meson.

However, researchers face a challenge as the expected mass of Bc+ mesons is only marginally greater than that of Bc+ mesons, resulting in photons with very low energy that are challenging to detect using traditional methods.

Instead of standard photon identification techniques, scientists looked for photons that transformed into electron-positron pairs in the ATLAS tracking detector, leaving behind a trail of densely charged particles emerging from a common origin distinct from the initial proton-proton collision.

The lateral momentum of these tracks is around 100 MeV, significantly lower than typical values analyzed in ATLAS studies.

Consequently, the team had to implement a specialized trajectory reconstruction method to successfully identify the photons and confirm the existence of the Bc*+ meson.

The measured mass difference between the Bc*+ meson and the Bc+ meson stands at 64.5 ± 1.4 MeV.

According to the physicists, “This is within the range of available theoretical predictions, though it slightly diverges from the latest high-precision calculations.”

These findings will significantly contribute to theoretical models explaining the mass of particles with heavier quarks and enhance our understanding of the strong nuclear force.

The team’s research will soon be published in the journal Physical Review Letters.

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Collaboration with ATLAS. 2026. Observation of Bc*+ Mesons using the ATLAS detector. Physical Review Letters, in press. arXiv: 2605.16228

Source: www.sci.news

Clues to Exotic Dark Matter Particles Could Be Found in LHC Data

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SEI 266779422

ATLAS Detector of the Large Hadron Collider

Xenotar/Getty Images

The theoretical particles known as axions have attracted the attention of physicists for decades, as they are significant candidates for identifying dark matter. Recent research suggests that we might not need new experiments to discover these exotic particles; evidence could already be embedded in existing data from previous particle collider experiments.

Particle colliders like the Large Hadron Collider (LHC), located at CERN near Geneva, Switzerland, discover new particles by colliding protons and ions, analyzing the resulting debris. Now, Gustabo Gilda Silveyra and his team at CERN are exploring another avenue: can we detect when a proton or ion emits a new particle during acceleration? Their findings indicate that this may indeed be possible.

The axion was theorized in the 1970s as part of a pivotal solution to a significant problem in physics. Its importance surpasses even that of antimatter. Although the ongoing search for experimental evidence of axions has not yet yielded results, it raises the possibility that other particles resembling axions might exist. Due to their incredibly low mass, they bear a close resemblance to substantial quantities of light or photons, interacting together with the LHC.

This interaction primarily occurs when protons or ions are accelerated to astonishing energy levels. As these particles approach each other, they begin to emit radiation in the form of photons, which may then collide with one another. Researchers have modeled this scenario, replacing photons with axion-like particles. Their results indicate that accelerated protons exhibit a higher likelihood of generating axion-like particles compared to accelerated ions, with both producing photons simultaneously. Consequently, the team has identified collisions between protons and lead ions as optimal for uncovering signals related to axions influencing photons. The specific proton-lead ion collisions were executed at the LHC in 2016, and the researchers propose that data from these experiments might have been previously overlooked but could contain vital hints about new axion-like particles.

Lucien Haaland Lang from University College London has remarked that this approach presents an intriguing new pathway to uncover potential undiscovered particles, though he cautions about the challenges involved. “Such collision events are rare, and we must be cautious to differentiate our findings from background processes that may inadvertently mimic the signals we seek,” he notes.

Access to older LHC data poses challenges due to updates in software, according to Da Silveira. However, he expresses optimism regarding future experiments at the LHC. “We will be able to adjust the detector to capture this specific signal,” he states.

Identifying a particle signal analogous to an axion does not equate to discovering an actual axion, thus leaving one of the major unresolved questions in physics unanswered. Nonetheless, it expands our understanding of particle physics, prompting inquiries into how new particles might interact with known counterparts and whether they might help explain the enigmatic dark matter that permeates the universe.

Journal Reference: Physical Review Letter, In print

Topics:

  • Large Hadron Collider/
  • Particle Physics

Source: www.newscientist.com

Scientists Trace the Source of Exotic Particles

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In the universe, there’s an unseen flow of particles and energy that surrounds and passes through us. This phenomenon is akin to the force from Star Wars, though it is grounded in reality. This so-called “force” is a critical by-product of nuclear processes and high-energy particle interactions that maintain the universe, known as neutrinos.

Neutrinos are tiny subatomic particles that travel close to the speed of light without an electric charge, constantly flowing through us. As you read this, approximately 100 trillion neutrinos are passing through your body every second, yet you’re completely unaware of them! As fundamental components of the universe, neutrinos aren’t composed of smaller particles, making them elementary particles.

Neutrinos originate from nuclear and high-energy reactions. Most neutrinos reaching Earth come from nuclear reactors and various stars. These neutrinos are low-energy, about 400 kiloelectron volts (6 x 10-14 Joules). To put that in perspective, it would take nine quarters to match the energy contained in a single 12-ounce soda can. Additionally, neutrinos from beyond our solar system can strike Earth, possessing billions to trillions of electron volts of energy, which would require about 4 trillion yen to equal the energy of the same soda can.

Astrophysicists are eager to discover the origins of high-energy neutrinos emitted from deep space. They proposed that these neutrinos are generated by rapidly moving protons, known as cosmic rays that collide with unstable particles called pions. Physicists theorize that these collisions can generate high-energy gamma-ray photons and sometimes ultra-high-energy neutrinos. According to this hypothesis, neutrino detectors may observe a spike in detections from the same areas in the universe where gamma rays have been identified by other scientists.

To test this theory, the team analyzed neutrino detection data from the IceCube Neutrino Observatory in Antarctica. They noted that detectors like IceCube are one of three methods for scientists to uncover activities occurring in space, alongside gravitational wave detectors and telescopes. However, this is a challenging task, as scientists must wait for neutrinos to collide with atomic nuclei in water molecules. Such collisions produce a distinct blue light known as Cherenkov radiation that is measurable by the detector, and by evaluating the patterns of Cherenkov emissions, researchers can assess the energy levels of the incoming neutrinos.

The blue light depicted on this reactor exemplifies Cherenkov radiation. “HFIR refueling July 2015 (19944787756)” by Oak Ridge National Institute Licensed under CC by 2.0.

Once the neutrino detector was installed, the next task was to identify areas where gamma rays are typically found. To achieve this, astrophysicists utilized data from the Large High-Altitude Air Shower Observatory (LHAASO). This data revealed gamma rays originating from sections of the sky containing much of the Milky Way galaxy, known as the galactic plane. The research team created a sky map delineating areas where LHAASO scientists detected gamma rays and developed several model maps predicting potential neutrino events, comparing them against IceCube neutrino detection data. One model assumed neutrinos could emerge from anywhere on the galactic plane, while another suggested they would arise from regions with dense gas concentrations, and a third posited that neutrinos could be emitted from all directions in the sky.

Astrophysicists then evaluated these maps against 2,500 days of IceCube data collected between 2011 and 2018, during which approximately 900,000 high-energy neutrinos were identified. Statistical analysis revealed that slightly more neutrinos originated from the galactic plane, supporting the theory that these particles are produced when cosmic rays collide with pions. They focused on specific regions of the galaxy, particularly near the constellation Sagittarius, where the most significant neutrino detections occurred. They recommended that future research focus on this part of the sky to study high-energy particle collisions in the universe.


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Source: sciworthy.com