In a significant scientific achievement, the CMS experiment has verified the mass of the W boson with remarkable accuracy, aligning perfectly with Standard Model predictions.
Utilizing data from millions of particle collisions and advanced analytical techniques, this research marks a milestone in understanding the fundamental constituents of the universe.
Breakthrough in Particle Physics
In 2022, the Collider Detector at the Fermilab (CDF) experiment made an unexpected measurement of the W boson, one of nature’s force-carrying particles. Now, physicists on the Compact Muon Solenoid experiment at the Large Hadron Collider announced a new mass measurement of the W boson.
This new measurement, which is a first for the CMS experiment, uses a new technique that makes it the most elaborate investigation of the W boson’s mass to date. Following nearly a decade of analysis, CMS has found that the W boson’s mass is consistent with predictions, finally putting a multi-year-long mystery to rest.
Precision and Collaboration Enhance W Boson Study
The final analysis used 300 million events collected from the 2016 run of the LHC, and 4 billion simulated events. From this dataset, the team reconstructed and then measured the mass from more than 100 million W bosons. They found that the W boson’s mass is 80 360.2 ± 9.9 megaelectron volts (MeV), which is consistent with the Standard Model’s predictions of 80 357 ± 6 MeV. They also ran a separate analysis that cross-checks the theoretical assumptions.
“The new CMS result is unique because of its precision and the way we determined the uncertainties,” said Patty McBride, a distinguished scientist at the U.S. Department of Energy’s Fermi National Research Laboratory and the former CMS spokesperson. “We’ve learned a lot from CDF and the other experiments that have worked on the W boson mass question. We are standing on their shoulders, and this is one of the reasons why we are able to take this study a big step forward.”
Unveiling the Universe’s Subatomic Balance
Since the W boson was discovered in 1983, physicists on 10 different experiments have measured its mass.
The W boson is one of the cornerstones of the Standard Model, the theoretical framework that describes nature at its most fundamental level. A precise understanding of the W boson’s mass allows scientists to map the interplay of particles and forces, including the strength of the Higgs field and the merger of electromagnetism with the weak force, which is responsible for radioactive decay.
“The entire universe is a delicate balancing act,” said Anadi Canepa, deputy spokesperson of the CMS experiment and a senior scientist at Fermilab. “If the W mass is different from what we expect, there could be new particles or forces at play.”
Credit: Saskia Theresa Rodriguez, CERN
Advancements in Measurement Techniques
The new CMS measurement has a precision of 0.01%. This level of precision corresponds to measuring a 4-inch-long pencil to between 3.9996 and 4.0004 inches. But unlike pencils, the W boson is a fundamental particle with no physical volume and a mass that is less than a single atom of silver.
“This measurement is extremely difficult to make,” Canepa added. “We need multiple measurements from multiple experiments to cross-check the value.”
Enhancing Precision in Fundamental Particle Detection
The CMS experiment is unique from the other experiments that have made this measurement because of its compact design, specialized sensors for fundamental particles called muons and an extremely strong solenoid magnet that bends the trajectories of charged particles as they move through the detector.
“CMS’s design makes it particularly well-suited for precision mass measurements,” McBride said. “It’s a next-generation experiment.”
Challenges and Innovations in Particle Measurement
Because most fundamental particles are incredibly short-lived, scientists measure their masses by adding up the masses and momenta of everything they decay into. This method works well for particles like the Z boson, a cousin of the W boson, which decays into two muons. But the W boson poses a big challenge because one of its decay products is a tiny fundamental particle called a neutrino.
“Neutrinos are notoriously difficult to measure,” said Josh Bendavid, a scientist at the Massachusetts Institute of Technology who worked on this analysis. “In collider experiments, the neutrino goes undetected, so we can only work with half the picture.”
Working with just half the picture means that the physicists need to be creative. Before running the analysis on real experimental data, the scientists first simulated billions of LHC collisions.
“In some cases, we even had to model small deformations in the detector,” Bendavid said. “The precision is high enough that we care about small twists and bends; even if they’re as small as the width of a human hair.”
The Art and Science of Collider Experiments
Physicists also need numerous theoretical inputs, such as what is happening inside the protons when they collide, how the W boson is produced, and how it moves before it decays.
“It’s a real art to figure out the impact of theory inputs,” McBride said.
Long-Term Commitment to Particle Physics Research
In the past, physicists used the Z boson as a stand-in for the W boson while calibrating their theoretical models. While this method has many advantages, it also adds a layer of uncertainty into the process.
“Z and W bosons are siblings, but not twins,” said Elisabetta Manca, a researcher at the University of California Los Angeles and one of the analyzers. “Physicists need to make a few assumptions when extrapolating from the Z to the W, and these assumptions are still under discussion.”
To reduce this uncertainty, CMS researchers developed a novel analysis technique that uses only real W boson data to constrain the theoretical inputs.
“We were able to do this effectively thanks to a combination of a larger data set, the experience we gained from an earlier W boson study, and the latest theoretical developments,” Bendavid said. “This has allowed us to free ourselves from the Z boson as our reference point.”
As part of this analysis, they also examined 100 million tracks from the decays of well-known particles to recalibrate a massive section of the CMS detector until it was an order of magnitude more precise.
“This new level of precision will allow us to tackle critical measurements, such as those involving the W, Z, and Higgs bosons, with enhanced accuracy,” Manca said.
The most challenging part of the analysis was its time intensiveness, since it required creating a novel analysis technique and developing an incredibly deep understanding of the CMS detector.
“I started this research as a summer student, and now I’m in my third year as a postdoc,” Manca said. “It’s a marathon, not a sprint.”
Reference: “Measurement of the W boson mass in proton-proton collisions at √s= 13 TeV” by CMS Collaboration
17 September 2024.
The Compact Muon Solenoid (CMS) experiment is funded in part by the Department of Energy’s Office of Science and the National Science Foundation. It is one of two large general-purpose experiments at the Large Hadron Collider (LHC) at CERN, the European Particle Physics Laboratory.
Fermilab is the host laboratory in the U.S. that facilitates the participation of hundreds of USCMS physicists from more than 50 university groups and plays a leading role in detector construction and operations, computing and software, and data analysis.
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16 Comments
Researchers should not expect the public to have limited knowledge. The particle collider is essentially a huge fig leaf that contemporary physics has been waving around, using countless errors to cover up the most primitive, simplest, and lowest level of error.
Please witness the exemplary collaboration between theoretical physicists and experimentalists ( https://scitechdaily.com/microscope-spacecrafts-most-precise-test-of-key-component-of-the-theory-of-general-relativity/#comment-854286 ).
My ruthless repetition may make some people unhappy, but in order to fight against rampant pseudoscience, I can only do so.
Let us continue to witness together the dirtiest and ugliest era for science and humanities in the development history of human society.
The physical phenomena observed by researchers in experiments can never be the whole, let alone the essence of nature.
Ask the researchers think deeply:
1. How is the mass of an object determined in scientific research?
2. What is the mass of a topological vortex?
3. Can topological vortices generate gravitation?
4. Is it possible to form energy gaps for topological vortices and their fractal structures?
No one reads more than a few lines of your off-topic – and, ironically, obviously pseudoscience – comments.
VERY GOOD.
Your words and actions are the best ironical for some people in physics.
Ask the researchers think deeply:
1. How is the mass of an object determined in scientific research?
2. What is the mass of a topological vortex?
3. Can topological vortices generate gravitation?
4. Is it possible to form energy gaps for topological vortices and their fractal structures?
I have a query in an attempt to alleviate myself of some ignorance here: as so far un-measured; is possible there is such a phenomenon as anti-mass? Could Z-Boson be a carrier of this? Could measurement of this be found to mirror the mass of the W-Boson? And would a field of anti-mass be indicative of Big-Bang theory explicative? Would it be similarly relatable as the electromagnetic fields may be with scalar fielding applications?
Please do allow me wrong, right, and/or open-ended answers to this query?
Thanks for your considerations:o)
And may you & yours have much to match with gratitude;o)
The universe does not write algebra, formulas, or fractions. The universe is a superposition, deflection, and entanglement of geometric shapes. It is the interaction and synchronization effect of countless topological vortices and their fractal structures. The formation of energy gaps between topological vortices is crucial for the evolution of spatiotemporal motion from low dimensional spacetime to high-dimensional spacetime. Absolute symmetry is mainly manifested between topological vortices and their antivortices, and is difficult to manifest in the high-dimensional spacetime formed by their interactions. Please consider: What is the mass of a topological vortices?
Topological vortex research reflections on the philosophy and methodology of science help us understand the nature essence of science and the limitations of scientific methods. This not only has guiding significance for scientific research itself, but also has important implications for science education and popularization.
Best wishes to you.
The simplest way to see why gravity cannot have antigravity or antimass is to see how general relativity successfully models it with curved space (of spacetime). you cannot “anti-curve” space.
If they’re happy, I’m happy for them. But will there ever be a practical, socially useful application of anything they’re “solving” with this ultra-expensive toy?
Oh yes. The improved sensors and data handling softwares have already found their way into medical instruments, as they usually do. See CERN’s review:
“CERN’s impact on medical technology
Frontier instruments like the LHC and its detectors not only push back the boundaries of our knowledge, but also catalyse innovative technology for medical applications, writes Manuela Cirilli.”
It’s a long list, too long to summarize here. So search for it and have a read!
It is a nice achievement!
But for new physics the neutrino sector seems more promising, since their mass oscillations doesn’t fit withing the standard model and could explain matter/antimatter asymmetry. And e.g. a sterile neutrino extension is a WIMP candidate.
Topological vortices exhibit parity conservation, charge conjugation, and time reversal symmetry. Once the topological vortex is formed, it is difficult to determine which one is a vortex and which one is an antivortex. In the subsequent superposition, deflection, and entanglement, due to the formation of energy gaps and possible cancellation or annihilation, it is difficult for the originally symmetrical vortices and anti vortices to maintain their original state. Its nature essence is that topological vortices transform from one symmetry to another via spin self-organization, rather than breaking the symmetry of the system.
In terms of the relationship between matter and antimatter, they mainly manifest between topological vortices and their corresponding antivortices, rather than the high-dimensional spacetime matter formed by their interactions. This implies that the so-called asymmetry between matter and antimatter is a misunderstanding for high-dimensional spacetime matter. The hierarchical structure of matter is crucial for understanding matter and antimatter. It is difficult to synthesize or observe strictly speaking matter and antimatter in high-dimensional spacetime that constructed by topological vortex interactions.
Topological vortex research reflections on the philosophy and methodology of science help us understand the nature essence of science and the limitations of scientific methods. This not only has guiding significance for scientific research itself, but also has important implications for science education and popularization.
Physics is just so interesting. The physical phenomena observed by researchers in experiments are always appearances, never the natural essence of things. The natural essence of things needs to be extracted and sublimated based on mathematical theories via appearances , rather than being imagined arbitrarily.
Theoretical basis:
(1) Traditional physics: based on mathematical formalism, experimental verification and arbitrary imagination.
(2) Topological Vortex Theory: Although also based on mathematics (such as topology), it focuses more on non intuitive geometry and topological structures, challenging traditional physical intuition.
Extension of the Standard Model: Topological Vortex Theory points out the limitations of the Standard Model in describing the large-scale structure of the universe, proposes the need to consider non-standard model components such as dark matter and dark energy, and suggests that topological vortex fields may be key to understanding these phenomena.
Topological vortex theory heralds innovative technologies such as topological electronics, topological smart batteries, topological quantum computing, etc., which may bring low-energy electronic components, almost inexhaustible currents, and revolutionary computing platforms, etc.
Topology tells us that topological vortices and antivortices can form new spacetime structures via the synchronous effect of superposition, deflection, or twisting of them. In fact, mathematics does not tell us that there must be God particles, ghost particles, fermions, or bosons present. Today, so-called official (such as PRL, Nature, Science, PNAS, etc.) in physics stubbornly believes that two sets of cobalt-60 rotating in opposite directions can become two sets of objects that mirror each other, is a typical case that pseudoscience is rampant and domineering. Please witness the exemplary collaboration between theoretical physicists and experimentalists (https://scitechdaily.com/microscope-spacecrafts-most-precise-test-of-key-component-of-the-theory-of-general-relativity/#comment-854286).
Let us continue to witness together the dirtiest and ugliest era in the scientific and humanistic history of human society. The laws of nature will not change due to misleading of so-called academic publications.