American theoretical physicist Joseph Polczynski once said that the existence of magnetic monopoles is “one of the safest bets you can make about physics that has yet to be seen.” In the search for these particles that have magnetic charges and are predicted by several theories that extend the standard model, Moedal (Monopole and Exotic Detectors at the LHC) Although the collaboration has yet to prove Polczynski correct, its latest discovery represents a major advance. The new results narrow the search window for these hypothetical particles.
At CERN's Large Hadron Collider (LHC), interactions between protons or heavy ions can produce pairs of magnetic monopoles.
In collisions between protons, protons can be formed from a single virtual photon (Dorrell-Yang mechanism) or from the fusion of two virtual photons (photon fusion mechanism).
Through a process called the Schwinger mechanism, pairs of magnetic monopoles can also be generated from the vacuum of huge magnetic fields produced by near-miss collisions of heavy ions.
Since starting data acquisition in 2012, MoEDAL has achieved several firsts, including conducting the first search for magnetic monopoles produced by photon fusion and Schwinger mechanisms at the LHC. Ta.
inside First part of the latest researchMoEDAL physicists explored monopoles and highly charged objects (HECOs) produced via the Dorell-Yang mechanism and the photon fusion mechanism.
This search was based on proton-proton collision data collected during Experiment 2 at the LHC using the complete MoEDAL detector for the first time.
The complete detector consists of two main systems that sense magnetic monopoles, HECO, and other highly ionizing virtual particles.
First, magnetic monopole and HECO trajectories can be permanently registered without background signals from standard model particles. The second system consists of an approximately 1-ton capture volume designed to capture magnetic monopoles.
Although the researchers did not find any magnetic monopoles or HECOs in their latest scan of the trapping volume, the masses and production rates of these particles were determined for different values ​​of particle spin, a unique form of angular momentum. limits have been set.
For magnetic monopoles, a mass limit of 1 to 10 times the Dirac charge (gD), the basic unit of magnetic charge, is set, excluding the existence of monopoles with masses as high as about 3.9 trillion electron volts (TeV). I did. .
For HECO, a mass limit was established for charges from 5e to 350e, where e is the electronic charge, and the presence of HECO with masses in the range up to 3.4 TeV was excluded.
“MoEDAL's search reach for both monopoles and HECOs allows the collaboration to explore vast swaths of the theoretical 'discovery space' for these hypothetical particles,” said a spokesperson for the MoEDAL collaboration. said Dr. James Pinfold.
in their second studyMoEDAL scientists focused on searching for monopoles produced via the Schwinger mechanism in heavy ion collision data collected during LHC Experiment 1.
In a unique effort, we scanned a decommissioned section of the CMS experimental beam pipe for trapped monopoles instead of the trapping volume of the MoEDAL detector.
Again, the team found no monopoles, but set the strongest mass constraints yet for Schwinger monopoles with charges between 2 gD and 45 gD, ruling out the existence of monopoles with masses up to 80 GeV. did.
“A crucial aspect of the Schwinger mechanism is that the production of complex monopoles is not suppressed compared to the production of elementary monopoles, as is the case with Dorell-Yang and photon fusion processes,” Pinfold said. Ta.
“Therefore, if monopoles are composite particles, this and the previous Schwinger monopole search may have been the first ever chance to observe monopoles.”
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Moedal collaboration. 2024. Searching for highly ionized particles in pp collisions in LHC Run-2 using the Full MoEDAL detector. arXiv: 2311.06509
B. Acharya other. 2024. MoEDAL explores magnetic monopoles generated by the Schwinger effect in CMS beam pipes. arXiv: 2402.15682
Source: www.sci.news
