From Yale via Vox: “Why physicists really, really want to find a new subatomic particle”

Yale University

Vox

Sep 21, 2016
Brian Resnick

The latest search for a new particle has fizzled. Scientists are excited, and a bit scared.

Particle physicists are begging nature to reveal the secrets of the universe. The universe isn’t talking back. FABRICE COFFRINI/AFP/Getty Images

Particle physicists are rather philosophical when describing their work.

“Whatever we find out, that is what nature chose,” Kyle Cranmer, a physics professor at New York University, tells me. It’s a good attitude to have when your field yields great disappointments.

For months, evidence was mounting that the Large Hadron Collider, the biggest and most powerful particle accelerator in the world, had found something extraordinary: a new subatomic particle, which would be a discovery surpassing even the LHC’s discovery of the Higgs boson in 2012, and perhaps the most significant advance since Einstein’s theory of relativity.

LHC at CERN

And yet, nature had other plans.

In August, the European Organization for Nuclear Research (CERN) reported that the evidence for the new particle had run thin. What looked like a promising “bump” in the data, indicating the presence of a particle with a unique mass, was just noise.

But to Cranmer — who has analyzed LHC data in his work — the news did not equate failure. “You have to keep that in mind,” he says. “Because it can feel that way. It wasn’t there to be discovered. It’s like being mad that someone didn’t find an island when someone is sailing in the middle of the ocean.”

What’s more, the LHC’s journey is far from over. The machine is expected to run for another 20 or so years. There will be more islands to look for.

“We’re either going to discover a bunch of new particles or we will not,” Cranmer says. “If we find new particles, we can study them, and then we have a foothold to make progress. And if we don’t, then [we’ll be] staring at a flat wall in front figuring out how to climb it.”

This is a dramatic moment, one that could provoke “a crisis at the edge of physics,” according to a New York Times op-ed. Because if the superlative LHC can’t find answers, it will cast doubt that answers can be found experimentally.

From here, there are two broad scenarios that could play out, both of which will vastly increase our understanding of nature. One scenario will open up physics to a new world of understanding about the universe; the other could end particle physics as we know it.

The physicists themselves can’t control the outcome. They’re waiting for nature to tell them the answers.

Why do we care about new subatomic particles anyway?

A graphic showing traces of collision of particles at the Compact Muon Solenoid (CMS) experience is pictured with a slow speed experience at Universe of Particles exhibition of the the European Organization for Nuclear Research (CERN) on December 13, 2011, in Geneva. FABRICE COFFRINI/AFP/GettyImages

The LHC works by smashing together atoms at incredibly high velocities. These particles fuse and can form any number of particles that were around in the universe from the Big Bang onward.

When the Higgs boson was confirmed in 2012, it was a cause for celebration and unease.

CERN CMS Higgs Event

CERN ATLAS Higgs Event

The Higgs was the last piece of a puzzle called the standard model, which is a theory that connects all the known components of nature (except gravity) together in a balanced, mathematical equation.

The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth

The Higgs was the final piece that had been theorized to exist but never seen.

After the Higgs discovery, the scientists at the LHC turned their hopes in a new direction. They hoped the accelerator could begin to find particles that had never been theorized nor ever seen. It was like going from a treasure hunt with a map to chartering a new ocean.

They want to find these new subatomic particles because even though the standard model is now complete, it still can’t answer a lot of lingering questions about the universe. Let’s go through the two scenarios step by step.

Scenario 1: There are more subatomic particles! Exciting!

If the LHC finds new subatomic particles, it lend evidence to a theory known as supersymmetry. Supersymmetry posits that all the particles in the standard model must have a shadow “super partner” that spins in a slightly different direction.

Standard model of Supersymmetry DESY

Scientists have never seen one of these supersymmetrical particles, but they’re keen to. Supersymmetry could neatly solve some of the biggest problems vexing physicists right now.

Such as:

1) No one knows what dark matter is

One of these particles could be what scientists call “dark matter,” which is theorized to make up 27 percent of the universe. But we’ve never seen dark matter, and that leaves a huge gaping hole in our understanding of the how the universe formed and exists today.

“It could be that one particle is responsible for dark matter,” Cranmer explains. Simple enough.

2) The Higgs boson is much too light

The Higgs discovery was an incredible triumph, but it also contained a mystery to solve. The boson — at 126 GeV (giga electron volts) — was much lighter than the standard model and the math of quantum mechanics suggests it should be.

Why is that a problem? Because it’s a wrinkle to be ironed out in our understanding of the universe. It suggests the standard model can’t explain everything. And physicists want to know everything.

“Either nature is sort of ugly, which is entirely conceivable, and we just have to live with the fact that the Higgs boson mass is light and we don’t know why,” Ray Brock, a Michigan State University physicist who has worked on the LHC, says, “or nature is trying to tell us something.”

It could be that a yet-to-be-discovered subatomic particle interacts with the Higgs, making it lighter than it ought to be.

3) The standard model doesn’t unify the forces of the universe

There are four major forces that make the universe tick: the strong nuclear force (which holds atoms together), the weak nuclear force (what makes Geiger counters tick), electromagnetism (you’re using it right now, reading this article on an electronic screen), and gravity (don’t look down.)

Scientists aren’t content with the four forces. They, for decades, have been trying to prove that the universe works more elegantly, that, deep down, all these forces are just manifestations of one great force that permeates the universe.

Physicists call this unification, and the standard model doesn’t provide it.

“If we find supersymmetry at the LHC, it is a huge boost to the dream that three of the fundamental forces we have [all of them except gravity] are all going to unify,” Cranmer says.

4) Supersymmetry would lead to more particle hunting

If scientists find one new particle, supersymmetry means they’ll find many more. That’s exciting. “It’s not going to be just one new particle that we discovered, and yay!” Cranmer says. “We’re going to be finding new forces, or learn something really deep about the nature of space and time. Whatever it is, it’s going to be huge.”

Scenario 2: There are no new subatomic particles. Less exciting! But still interesting. And troubling.

The LHC is going to run for around another 20 years, at least. There’s a lot of time left to find new particles, even if there is no supersymmetry. “This is what always blows my mind,” Brock says. “We’ve only taken about 5 percent of the total planned data that the LHC is going to deliver until the middle 2020s.”

But the accelerator also might not find anything. If the new particles aren’t there to find, the LHC won’t find them. (Hence, the notion that physicists are looking for “what nature chose.”)

But again, this doesn’t represent a failure. It will actually yield new insights about the universe.

“It would be a profound discovery to find that we’re not going to see anything else,” Cranmer says.

1) For one, it would suggest that supersymmetry isn’t the answer

If supersymmetry is dead, then theoretical physicists will have to go back to the drawing board to figure out how to solve the mysteries left open by the standard model.

“If we’re all coming up empty, we would have to question our fundamental assumptions,” Sarah Demers, a Yale physicist, tells me. “Which is something we’re trying to do all the time, but that would really force us.”

2) The answers exist, but they exist in a different universe

If the LHC can’t find answers to questions like “why is the Higgs so light?” scientists might grow to accept a more out-of-the-box idea: the multiverse.

That’s the idea where there are tons of universes all existing parallel to one another. It could be that “in most of [the universes], the Higgs boson is really heavy, and in only in very unusual universes [like our own] is the Higgs boson so light that life can form,” Cranmer says.

Basically: On the scale of our single universe, it might not make sense for the Higgs to be light. But if you put it together with all the other possible universes, the math might check out.

There’s a problem with this theory, however: If heavier Higgs bosons exist in different universes, there’s no possible way to observe them. They’re in different universes!

“Which is why a lot of people hate it, because they consider it to be anti-science,” Cranmer says. “It might be impossible to test.”

3) The new subatomic particles do exist, but the LHC isn’t powerful enough to find them

In 20 years, if the LHC doesn’t find any new particles, there might be a simple reason: These particles are too heavy for the LHC to detect.

This is basic E=mc2 Einstein: The more energy in the particle accelerator, the heavier the particles it can create. The LHC is the most powerful particle accelerator in the history of man, but even it has its limits.

So what will physicists do? Build an even bigger, even smashier particle collider? That’s an option. There are currently preliminary plans in China for a collider double the size of the LHC.

Building a bigger collider might be a harder sell for international funding agencies. The LHC was funded in part because of the quest to confirm the Higgs. Will governments really spend billions on a machine that may not yield epic insights?

“Maybe we were blessed as a field that we always had a target or two to shoot for. We don’t have that anymore,” says Markus Klute, an MIT physicist stationed at CERN in Europe. “It’s easier to explain to the funding agencies specifically that there’s a specific endpoint.”

The LHC will keep running for the foreseeable future. But it could prove a harder task to make the case to build a new collider.

Either way, these are exciting times for physics

Dean Mouhtaropoulos/Getty Images

“I think we have had a tendency to be prematurely depressed,” Demers says. “It’s never a step backward to learn something new,” even if the news is negative. “Ruling out ideas teaches us an incredible amount.”

And she says that even if the LHC can never find another particle, it can still produce meaningful insights. Already, her colleagues are using it to help determine why there’s so much more matter than antimatter in the universe. And she reminds me the LHC can still teach us more about the mysterious Higgs. We will be able to measure it to a more precise degree.

Brock, the MSU physicist, notes that since the 1960s, physicists have been chasing the standard model. Now they don’t quite know what they’re chasing. But they know it will change the world.

“I can’t honestly say in all those 40 years, I’ve been exploring,” Brock says. “I’ve been testing the standard model. The Higgs boson was the last missing piece. Now, we have to explore.”

See the full article here .

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Stem Education Coalition

Yale University comprises three major academic components: Yale College (the undergraduate program), the Graduate School of Arts and Sciences, and the professional schools. In addition, Yale encompasses a wide array of centers and programs, libraries, museums, and administrative support offices. Approximately 11,250 students attend Yale.

From AARNet: “New record set for elephant data flow over AARNet”

AARNet

A new record set for the for the ARC Centre of Excellence in Particle Physics at the University of Melbourne: 53 terabytes transferred in 24hrs sustained at nearly 5 gigabits per second.

“I think we’ve made a new record for us. 53 terabytes transferred in 24hrs, at 100% efficiency,” reported Sean Crosby to AARNet’s eResearch team. Crosby is a research computing scientist working at the ARC Centre of Excellence for Particle Physics at the Terascale (CoEPP) at the University of Melbourne. He is referring to a recent elephant data flow over the AARNet network between the University of Melbourne and a research network-connected site located in Germany.

Data processing for the ATLAS Experiment

This huge data flow forms part of the CoEPP’s activities as an ATLAS experiment Tier2 site for the Worldwide Large Hardron Collider Computing Grid (WLCG). The CoEPP is one of the 170+ grid-connected computing centres in 42 countries worldwide that provide the linked-up computing and storage facilities required for analysing the ~30 Petabytes (30 million gigabytes) of data CERN’s Large Hadron Collider (LHC) produces annually.

Helping scientists further our understanding of the Universe

Physicists are using the LHC to recreate the conditions of the Universe just after the ‘Big Bang’. They are searching for new discoveries in the head-on collisions of protons of extraordinarily high energy to further our understanding of energy and matter. Following the discovery of the Higgs boson in 2012, data from the ATLAS experiment allows in-depth investigation of the boson’s properties and the origin of mass.

The reported 100% efficiency of this particular big data transfer between Australian and Germany, clocked at nearly 5 gigabits per second sustained over 24 hours, is a great example of the reliability and scalability of the AARNet network to meet the needs of data-intensive research on demand.

See the full article here .

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AARNet provides critical infrastructure for driving innovation in today’s knowledge-based economy

Australia’s Academic and Research Network (AARNet) is a national resource – a National Research and Education Network (NREN). AARNet provides unique information communications technology capabilities to enable Australian education and research institutions to collaborate with each other and their international peer communities.

From CERN Courier: “LHC hits 2016 luminosity target”

CERN Courier

Sep 16, 2016
No writer credit found

Integrated luminosity

At the end of August, two months ahead of schedule, the integrated luminosity delivered by the LHC reached the 2016 target value of 25 fb–1 in both the ATLAS and CMS experiments. The milestone is the result of a large group of scientists and technical experts who work behind the scenes to keep the 27 km-circumference machine operating at the highest possible performance.

Following a push to produce as many proton–proton collisions as possible before the summer conferences, several new ideas, such as a novel beam-production technique in the injectors, have been incorporated to boost the LHC performance. Thanks to these improvements, over the summer the LHC was routinely operating with peak luminosities 10%–15% above the design value of 1034 cm–2 s–1.

This is a notable success, especially considering that a temporary limitation in the Super Proton Synchrotron only allows the injection of 2220 bunches per beam instead of the foreseen 2750, and that the LHC energy is currently limited to 6.5 TeV instead of the nominal 7 TeV. The excellent availability of all the key systems of the LHC is one of the main reasons behind these achievements.

The accelerator team is now gearing up for the season finale. Following a technical stop, a forward proton–proton physics run took place in mid-September. Proton–proton physics is scheduled to continue until the last week in October, after which proton–lead physics will take over for a period of one month. The LHC and its experiments can look forward to the completion of what is already a very successful year.

See the full article here .
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THE FOUR MAJOR PROJECT COLLABORATIONS

ATLAS

ALICE

CMS

LHCb

LHC

From Symmetry: “The secret lives of long-lived particles”

Symmetry

09/16/16
Sarah Charley

A theoretical species of particle might answer nearly every question about our cosmos—if scientists can find it.

ATLAS collaboration

The universe is unbalanced.

Gravity is tremendously weak. But the weak force, which allows particles to interact and transform, is enormously strong. The mass of the Higgs boson is suspiciously petite. And the catalog of the makeup of the cosmos? Ninety-six percent incomplete.

Almost every observation of the subatomic universe can be explained by the Standard Model of particle physics—a robust theoretical framework bursting with verifiable predictions.

The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

But because of these unsolved puzzles, the math is awkward, incomplete and filled with restrictions.

A few more particles would solve almost all of these frustrations. Supersymmetry (nicknamed SUSY for short) is a colossal model that introduces new particles into the Standard Model’s equations.

Standard model of Supersymmetry DESY

It rounds out the math and ties up loose ends. The only problem is that after decades of searching, physicists have found none of these new friends.

But maybe the reason physicists haven’t found SUSY (or other physics beyond the Standard Model) is because they’ve been looking through the wrong lens.

“Beautiful sets of models keep getting ruled out,” says Jessie Shelton, a theorist at the University of Illinois, “so we’ve had to take a step back and consider a whole new dimension in our searches, which is the lifetime of these particles.”

In the past, physicists assumed that new particles produced in particle collisions would decay immediately, almost precisely at their points of origin. Scientists can catch particles that behave this way—for example, Higgs bosons—in particle detectors built around particle collision points. But what if new particles had long lifetimes and traveled centimeters—even kilometers—before transforming into something physicists could detect?

This is not unprecedented. Bottom quarks, for instance, can travel a few tenths of a millimeter before decaying into more stable particles. And muons can travel several kilometers (with the help of special relativity) before transforming into electrons and neutrinos. Many theorists are now predicting that there may be clandestine species of particles that behave in a similar fashion. The only catch is that these long-lived particles must rarely interact with ordinary matter, thus explaining why they’ve escaped detection for so long. One possible explanation for this aloof behavior is that long live particles dwell in a hidden sector of physics.

“Hidden-sector particles are separated from ordinary matter by a quantum mechanical energy barrier—like two villages separated by a mountain range,” says Henry Lubatti from the University of Washington. “They can be right next to each other, but without a huge boost in energy to get over the peak, they’ll never be able to interact with each other.”

High-energy collisions generated by the Large Hadron Collider could kick these hidden-sector particles over this energy barrier into our own regime. And if the LHC can produce them, scientists should be able to see the fingerprints of long-lived particles imprinted in their data.

LHC at CERN

Long-lived particles jolted into our world by the LHC would most likely fly at close to the speed of light for between a few micrometers and a few hundred thousand kilometers before transforming into ordinary and measurable matter. This incredibly generous range makes it difficult for scientists to pin down where and how to look for them.

But the lifetime of a subatomic particle is much like that of any living creature. Each type of particle has an average lifespan, but the exact lifetime of an individual particle varies. If these long-lived particles can travel thousands of kilometers before decaying, scientists are hoping that they’ll still be able to catch a few of the unlucky early-transformers before they leave the detector. Lubatti and his collaborators have also proposed a new LHC surface detector, which would extend their search range by many orders of magnitude.

Because these long-lived particles themselves don’t interact with the detector, their signal would look like a stream of ordinary matter spontaneously appearing out of nowhere.

“For instance, if a long lived particle decayed into quarks while inside the muon detector, it would mimic the appearance of several muons closely clustered together,” Lubatti says. “We are triggering on events like this in the ATLAS experiment.” After recording the events, scientists use custom algorithms to reconstruct the origins of these clustered particles to see if they could be the offspring of an invisible long-lived parent.

If discovered, this new breed of matter could help answer several lingering questions in physics.

“Long-lived particles are not a prediction of a single new theory, but rather a phenomenon that could fit into almost all of our frameworks for beyond-the-Standard-Model physics,” Shelton says.

In addition to rounding out the Standard Model’s mathematics, inert long-lived particles could be cousins of dark matter—an invisible form of matter that only interacts with the visible cosmos through gravity. They could also help explain the origin of matter after the Big Bang.

“So many of us have spent a lifetime studying such a tiny fraction of the universe,” Lubatti says. “We’ve understood a lot, but there’s still a lot we don’t understand—an enormous amount we don’t understand. This gives me and my colleagues pause.”

See the full article here .

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Symmetry is a joint Fermilab/SLAC publication.

From particlebites: “Searching for Magnetic Monopoles with MoEDAL”

particlebites

September 7, 2016
Julia Gonski
Article: Search for magnetic monopoles with the MoEDAL prototype trapping detector in 8 TeV proton-proton collisions at the LHC
Authors: The ATLAS Collaboration
Reference: arXiv:1604.06645v4 [hep-ex]

Somewhere in a tiny corner of the massive LHC cavern, nestled next to the veteran LHCb detector, a new experiment is coming to life.

The Monopole & Exotics Detector at the LHC, nicknamed the MoEDAL experiment, recently published its first ever results on the search for magnetic monopoles and other highly ionizing new particles. The data collected for this result is from the 2012 run of the LHC, when the MoEDAL detector was still a prototype. But it’s still enough to achieve the best limit to date on the magnetic monopole mass.

CERN

Magnetic monopoles are a very appealing idea. From basic electromagnetism, we expect to swap electric and magnetic fields under duality without changing Maxwell’s equations. Furthermore, Dirac showed that a magnetic monopole is not inconsistent with quantum electrodynamics (although they do not appear natually.) The only problem is that in the history of scientific experimentation, we’ve never actually seen one. We know that if we break a magnet in half, we will get two new magnetics, each with its own North and South pole (see Figure 1).

This is proving to be a thorn in the side of many physicists. Finding a magnetic monopole would be great from a theoretical standpoint. Many Grand Unified Theories predict monopoles as a natural byproduct of symmetry breaking in the early universe. In fact, the theory of cosmological inflation so confidently predicts a monopole that its absence is known as the “monopole problem”. There have been occasional blips of evidence for monopoles in the past (such as a single event in a detector), but nothing has been reproducible to date.

Enter MoEDAL. It is the seventh addition to the LHC family, having been approved in 2010. If the monopole is a fundamental particle, it will be produced in proton-proton collisions. It is also expected to be very massive and long-lived. MoEDAL is designed to search for such a particle with a three-subdetector system.

CERN: The LHC MoEDAL Experiment

The Nuclear Track Detector is composed of plastics that are damaged when a charged particle passes through them. The size and shape of the damage can then be observed with an optical microscope. Next is the TimePix Radiation Monitor system, a pixel detector which absorbs charge deposits induced by ionizing radiation. The newest addition is the Trapping Detector system, which is simply a large aluminum volume that will trap a monopole with its large nuclear magnetic moment.

The collaboration collected data using these distinct technologies in 2012, and studied the resulting materials and signals. The ultimate limit in the paper excludes spin-0 and spin-1/2 monopoles with masses between 100 GeV and 3500 GeV, and a magnetic charge > 0.5gD (the Dirac magnetic charge). See Figures 3 and 4 for the exclusion curves. It’s worth noting that this upper limit is larger than any fundamental particle we know of to date. So this is a pretty stringent result.

Cross-section upper limits at 95% confidence level for DY spin-1/2 monopole production as
a function of mass, with different charge models.

Cross-section upper limits at 95% confidence level for DY spin-1/2 monopole production as
a function of charge, with different mass models.

As for moving forward, we’ve only talked about monopoles here, but the physics programme for MoEDAL is vast. Since the detector technology is fairly broad-based, it is possible to find anything from SUSY to Universal Extra Dimensions to doubly charged particles. Furthermore, this paper is only published on LHC data from September to December of 2012, which is not a whole lot. In fact, we’ve collected over 25x that much data in this year’s run alone (although this detector was not in use this year.) More data means better statistics and more extensive limits, so this is definitely a measurement that will be greatly improved in future runs. A new version of the detector was installed in 2015, and we can expect to see new results within the next few years.

Further Reading:

CERN press release
The MoEDAL collaboration website
“The Phyiscs Programme of the MoEDAL experiment at the LHC”. arXiv.1405.7662v4 [hep-ph]
“Introduction to Magnetic Monopoles”. arxiv.1204.30771 [hep-th]
Condensed matter physics has recently made strides in the study of a different sort of monopole; see “Observation of Magnetic Monopoles in Spin Ice”, arxiv.0908.3568 [cond-mat.dis-nn]

See the full article here .

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What is ParticleBites?

ParticleBites is an online particle physics journal club written by graduate students and postdocs. Each post presents an interesting paper in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.

The papers are accessible on the arXiv preprint server. Most of our posts are based on papers from hep-ph (high energy phenomenology) and hep-ex (high energy experiment).

Why read ParticleBites?

Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.

Our goal is to solve this problem, one paper at a time. With each brief ParticleBite, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in particle physics.

Who writes ParticleBites?

ParticleBites is written and edited by graduate students and postdocs working in high energy physics. Feel free to contact us if you’re interested in applying to write for ParticleBites.

ParticleBites was founded in 2013 by Flip Tanedo following the Communicating Science (ComSciCon) 2013 workshop.

Flip Tanedo UCI Chancellor’s ADVANCE postdoctoral scholar in theoretical physics. As of July 2016, I will be an assistant professor of physics at the University of California, Riverside

It is now organized and directed by Flip and Julia Gonski, with ongoing guidance from Nathan Sanders.

From Sixth Tone: “Nobel Winner Says China Should Not Build Particle Collider”

Sixth Tone

Sep 05, 2016
Li You

A view of Compact Muon Solenoid (CMS) Cavern at the European Organization for Nuclear Research (CERN), Meyrin, Switzerland, Feb. 10, 2015. Richard Juilliart/AFP/VCG)

Renowned physicist argues that building the world’s largest accelerator would not be worth the money.

China’s ambitious plans to build its own particle collider will not be worth it, Nobel prize-winning physicist Chen-Ning Yang argued in a commentary published Sunday.

Circular Electron Positron Collider, possible map.http://america.pink/circular-electron-positron-collider_1000720.html

Construction on the Circular Electron Positron Collider (CEPC) is slated to start in 2021. Upon its completion in six years, it would be the world’s largest particle accelerator. With a circumference of at least 50 kilometers — its exact size has not yet been decided — it would be far larger than the current record-holding machine, the Large Hadron Collider (LHC) at the European Organization for Nuclear Research, better known as CERN, beneath the border shared by France and Switzerland.

LHC at CERN

Such massive colliders allow scientists to study the universe’s smallest particles. The LHC in 2012 proved the existence of the Higgs boson, an elusive particle that had long puzzled scientists.

CERN CMS Higgs Event

CERN ATLAS Higgs Event

An even larger accelerator, such as the one planned by China, could collide particles at even higher energies and make discoveries that are impossible with existing colliders. However, some people in the scientific community, including Yang, do not agree with the project.

In an article published on WeChat public account The Intellectual, the Chinese-born American physicist argues that the costs of building the super collider are too high and not worth it considering China’s current situation. Yang called the high cost of the collider “a bottomless pit,” comparing it to the Superconducting Super Collider project, which cost the U.S. $3 billion before being scrapped.

Yang, who won a Nobel prize in 1957, believes the money should be used to address social problems, and argues funding the collider will result in lower budgets for other valuable scientific research.

Chances of making any big discoveries are relatively low, Yang said. The CEPC would be used to search for so-called supersymmetry particles, which he says come from “a theory without experimental basis.” Moreover, Yang foresees the collider being run mostly by foreigners and being of little benefit to Chinese scientists. “Among the prominent high-energy physicists in the world, Chinese make up less than 1 or 2 percent,” he wrote.

Wang Yifang, head of the government-run Institute of High Energy Physics (IHEP), the entity behind the collider project, replied on Monday with an article of his own, also published on The Intellectual.

Wang denied that the cost of building CEPC would be endless, adding that international investment would cover 30 percent of the total expenses. He also said that 70 percent of the work would be done by Chinese scientists. Wang believes that building a large collider will attract overseas talent, cultivate young scientists at home, and be a leap for China in high-energy science.

Also in response to Yang’s commentary, Sixth Tone’s sister publication The Paper on Monday published an article based on an interview with Rudiger Voss, head of international relations at CERN in Switzerland.

Voss said that although the Chinese project would allow physicists to study the properties of the Higgs boson with greater precision and accuracy, the experiments would be limited in scope: The energy ranges of such experiments would be confined by the length of the tunnel, which in the case of China’s plans would be circular, and thus fixed.

Plans are currently underway for a new linear collider that would be the result of an international collaborative effort, and would build on the current experiments being carried out at CERN’s LHC. The International Linear Collider project would be extendable in length, allowing for proportional increases in energy levels.

According to media reports, the idea to build a Chinese super collider was first raised in 2012. Financial news outlet Caixin wrote in May that the government had yet to give any official comment.

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

There are five tones in Mandarin Chinese. When it comes to coverage of China, Sixth Tone believes there is room for other voices that go beyond buzzwords and headlines to tell the uncommon stories of common people.

Through fresh takes on trending topics, in-depth features, and illuminating contributions, Sixth Tone covers issues from the perspectives of those most intimately involved to highlight the nuances and complexities of today’s China.

We are a team of writers, editors, and researchers from within China and abroad. We belong to the state-funded Shanghai United Media Group, and share our offices with our sister publication, The Paper.

From Symmetry: “Winners declared in SUSY bet”

Symmetry

08/26/16
Kathryn Jepsen

Peter Munch Andersen

Physicists exchanged cognac in Copenhagen at the conclusion of a bet about supersymmetry and the LHC.

As a general rule, theorist Nima Arkani-Hamed does not get involved in physics bets.

“Theoretical physicists like to take bets on all kinds of things,” he says. “I’ve always taken the moral high ground… Nature decides. We’re all in pursuit of the truth. We’re all on the same side.”

But sometimes you’re in Copenhagen for a conference, and you’re sitting in a delightfully unusual restaurant—one that sort of reminds you of a cave—and a fellow physicist gives you the opportunity to get in on a decade-old wager about supersymmetry and the Large Hadron Collider. Sometimes then, you decide to bend your rule. “It was just such a jovial atmosphere, I figured, why not?”

That’s how Arkani-Hamed found himself back in Copenhagen this week, passing a 1000-Krone bottle of cognac to one of the winners of the bet, Director of the Niels Bohr International Academy Poul Damgaard.

Arkani-Hamed had wagered that experiments at the LHC would find evidence of supersymmetry by the arbitrary date of June 16, 2016. Supersymmetry, SUSY for short, is a theory that predicts the existence of partner particles for the members of the Standard Model of particle physics.

LHC at CERN

Standard model of Supersymmetry DESY

The deadline was not met. But in a talk at the Niels Bohr Institute, Arkani-Hamed pointed out that the end of the gamble does not equal the end of the theory.

“I was not a good student in school,” Arkani-Hamed explained. “One of my big problems was not getting homework done on time. It was a constant battle with my teachers… Just give me another week! It’s kind of like the bet.”

He pointed out that so far the LHC has gathered just 1 percent of the total amount of data it aims to collect.

With that data, scientists can indeed rule out the most vanilla form of supersymmetry. But that’s not the version of supersymmetry Arkani-Hamed would expect the LHC to find anyway, he said.

It is still possible LHC experiments will find evidence of other SUSY models—including the one Arkani-Hamed prefers, called split SUSY, which adds superpartners to just half of the Standard Model’s particles. And if LHC scientists don’t find evidence of SUSY, Arkani-Hamed pointed out, the theoretical problems it aimed to solve will remain an exciting challenge for the next generation of theorists to figure out.

“I think Winston Churchill said that in victory you should be magnanimous,” Damgaard said after Arkani-Hamed’s talk. “I know also he said that in defeat you should be defiant. And that’s certainly Nima.”

Arkani-Hamed shrugged. But it turned out he was not the only optimist in the room. Panelist Yonit Hochberg of the University of California, Berkeley conducted an informal poll of attendees. She found that the majority still think that in the next 20 years, as data continues to accumulate, experiments at the LHC will discover something new.

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Symmetry is a joint Fermilab/SLAC publication.

From CERN: “Roundup of ICHEP 2016 conference”

CERN

Roundup of ICHEP 2016 conference

Published on Aug 11, 2016

The ICHEP 2016 conference, held in Chicago, USA, came to a close on August 10th. At the conference the LHC collaborations presented more than 100 different new results, including many analyses based on newly taken 2016 data.

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Meet CERN in a variety of places:

Cern Courier

THE FOUR MAJOR PROJECT COLLABORATIONS

ATLAS

ALICE

CMS

LHCb

LHC

Quantum Diaries

From CERN: “LHC pushes limits of performance’

CERN

19 Aug 2016
Harriet Kim Jarlett

The Large Hadron Collider’s (LHC) performance continued to surpass expectations, when this week it achieved 2220 proton bunches in each of its counter-rotating beams – the most it will achieve this year.

This is not the maximum the machine is capable of holding (at full intensity the beam will have nearly 2800 bunches) but it is currently limited by a technical issue in the Super Proton Synchrotron (SPS).

“CERN Super Proton Synchrotron

“Performance is excellent, given this limitation,” says Mike Lamont, head of the Operations team. “We’re 10% above design luminosity (which we surpassed in June), we have these really long fills (where the beam is circulating for up to 20 hours or so) and very good collision rates. 2220 bunches is just us squeezing as much in as we can, given the restrictions, to maximize delivery to the experiments.”

As an example of the machine’s brilliant performance, with almost two months left in this year’s run it has already reached an integrated luminosity of 22fb-1 – very close to the goal for 2016 of 25fb-1 (up from 4fb-1 last year.)

Luminosity is an essential indicator of the performance of an accelerator, measuring the potential number of collisions that can occur in a given amount of time, and integrated luminosity (measured in inverse femtobarns, fb-1) is the accumulated number of potential collisions. At its peak, the LHC’s proton-proton collision rate reaches about 1 billion collisions per second giving a chance that even the rarest processes at the highest energy could occur.

The SPS is currently experiencing a small fault that could be exacerbated by high beam intensity – hence the number of proton bunches sent to the LHC per injection is limited to 96, compared to the normal 288.

“Once this issue is fixed in the coming year-end technical stop, we’ll be able to push up the number of bunches even further. Next year we should be able to go to new record levels,” says Lamont with a wry grin.

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Meet CERN in a variety of places:

Cern Courier

THE FOUR MAJOR PROJECT COLLABORATIONS

ATLAS

ALICE

CMS

LHCb

LHC

Quantum Diaries

From Nature- “China, Japan, CERN: Who will host the next LHC?”

Nature

[The title is in error. There will possibly be another particle accelerator, or more than one. But none will be the LHC. It is what it is. They will want and need a new name. Might I suggest superconducting super collider, and might I suggest the United States?]

19 August 2016
Elizabeth Gibney

Labs are vying to build ever-bigger colliders against a backdrop of uncertainty about how particle physicists will make the next big discoveries.

Whether the Large Hadron Collider will find phenomena outside the standard model of particle physics remains to be seen. Harold Cunningham/Getty

LHC at CERN

It was a triumph for particle physics — and many were keen for a piece of the action. The discovery of the Higgs boson in 2012 using the world’s largest particle accelerator, the Large Hadron Collider (LHC), prompted a pitch from Japanese scientists to host its successor. The machine would build on the LHC’s success by measuring the properties of the Higgs boson and other known, or soon-to-be-discovered, particles in exquisite detail.

But the next steps for particle physics now seem less certain, as discussions at the International Conference on High Energy Physics (ICHEP) in Chicago on 8 August suggest. Much hinges on whether the LHC unearths phenomena that fall outside the standard model of particle physics — something that it has not yet done but on which physicists are still counting — and whether China’s plans to build an LHC successor move forward.

The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

When Japanese scientists proposed hosting the International Linear Collider (ILC), a group of international scientists had already drafted its design. The ILC would collide electrons and positrons along a 31-kilometre-long track, in contrast to the 27-kilometre-long LHC, which collides protons in a circular track that is based at Europe’s particle-physics laboratory, CERN (See ‘World of colliders’).

ILC schematic

Because protons are composite particles made of quarks, collisions create a mess of debris. The ILC’s particles, by contrast, are fundamental and so provide the cleaner collisions more suited to precision measurements, which could reveal deviations from expected behaviour that point to physics beyond the standard model.

Higgs study

For physicists, the opportunity to carry out detailed study of the Higgs boson and the heaviest, ‘top’ quark, the second most recently discovered particle, is reason enough to build the facility. Japan’s Ministry of Education, Culture, Sports, Science and Technology (MEXT) was expected to make a call on whether to host the project — which could begin experiments around 2030 — in 2016. But the Japanese panel advising MEXT indicated last year that opportunities to study the Higgs boson and the top quark would not on their own justify building the ILC, and that it would wait until the end of the LHC’s first maximum-energy run – scheduled for 2018 – before making a decision.

That means the panel is not yet convinced by the argument that the ILC should be built irrespective of what the LHC finds, says Masanori Yamauchi, director-general of Japan’s High Energy Accelerator Research Organization (KEK) in Tsukuba who sat on an ICHEP panel at a session on future facilities. “That’s the statement hidden under their statement,” he says.

If the LHC discovers new phenomena, these would be further fodder for ILC study — and would strengthen the case for building the high precision machine.

US physicists have long backed building a linear collider. And a joint MEXT and US Department of Energy group is discussing ways to reduce the ILC’s costs, says Yamauchi, which are now estimated at US$10 billion. A reduction of around 15% is feasible — but Japan will need funding commitments from other countries before it formally agrees to host, he added.

Chinese competitor

Snapping at Japan’s heels is a Chinese team. In the months after the Higgs discovery, a team of physicists led by Wang Yifang, director of the Institute of High Energy Physics in Beijing, floated a plan to host a collider in the 2030s, also partially funded by the international community and focused on precision measurements of the Higgs and other particles.

Circular rather than linear, this 50–100-kilometre-long electron–positron smasher would not reach the energies of the ILC. But it would require the creation of a tunnel that could allow a proton–proton collider — similar to the LHC, but much bigger — to be built at a hugely reduced cost.

Wang and his team this year secured around 35 million yuan (US$5 million) in funding from China’s Ministry of Science and Technology to continue research and development for the project, Wang told the ICHEP session. Last month, China’s National Development and Reform Commission turned down a further request from the team for 800 million yuan, but other funding routes remain open, Wang said, and the team now plans to focus on raising international interest in the project.

By affirming worldwide interest in Higgs physics, the Chinese proposal bolsters Japan’s case for building the ILC, says Yamauchi. But if it goes ahead, it could drain international funding from the ILC and put its future on shakier ground. “It may have a negative impact,” he says.

Super-LHC

In the future, the option to use China’s electron–positron collider as the basis for a giant proton–proton collider could interfere with CERN’s own plans for a 100-kilometre-circumference circular machine that would smash protons together at more than 7 times the energy of the LHC. Until the mid-2030s, CERN will be busy with an upgrade that will raise the intensity — but not the energy — of the LHC’s proton beam. And by that time, China might have a suitable tunnel that could make it harder to get backing for this ‘super-LHC’.

At ICHEP, Fabiola Gianotti, CERN’s director-general, floated an interim idea: souping up the energy of the LHC beyond its current design by installing a new generation of superconducting magnets by around 2035. This would provide a relatively modest boost in energy — from 14 teraelectronvolts (TeV) to 20 TeV — that would have a strong science case if the LHC finds new physics at 14 TeV, said Gianotti. Its $5-billion price tag could be paid for out of CERN’s regular budget.

For decades, successive facilities have found particles predicted by the standard model, and neither the LHC nor any of its proposed successors is guaranteed to find new physics. Questions asked at the ICHEP session revealed some soul-searching among attendees, including a plea to reassure young high-energy physicists about the future of the field and contemplation of whether money would be better spent on other approaches rather than ever-bigger accelerators.

Indeed, the US is betting on neutrinos, fundamental particles that could reveal physics beyond the standard model, not colliders. The Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois, hopes to become the world capital of neutrino physics by hosting the $1-billion Long-Baseline Neutrino Facility, which will beam neutrinos to a range of detectors starting in 2026.

LBMF/DUNE map from FNAL, Batavia, IL to SURF, SD, USA; DUNE’s Argon tank; SURF caverns for science

Funding will require approval from US Congress in 2017. But at the ICHEP session, Fermilab director Nigel Lockyer was confident: “We are beyond the point of no return. It is happening.”

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Nature is a weekly international journal publishing the finest peer-reviewed research in all fields of science and technology on the basis of its originality, importance, interdisciplinary interest, timeliness, accessibility, elegance and surprising conclusions. Nature also provides rapid, authoritative, insightful and arresting news and interpretation of topical and coming trends affecting science, scientists and the wider public.