Stephen Sekula steve@hub.polari.us

Dallas, TX, USA

Husband; Associate Professor of Physics; I teach at SMU in Dallas, TX; I study the Higgs Particle with the ATLAS Experiment at the Large Hadron Collider at CERN; writer and blogger; drummer; programmer; teacher; scientist; traveler; runner; gardener; open-source aficionado.

  • Astronomy Picture of the Day for 2020-10-02 12:30:01.529666

    Astronomy Picture of the Day (Unofficial) at 2020-10-02T17:30:02Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2020 October 2
    See Explanation.  Clicking on the picture will download
the highest resolution version available.

    Biking to the Moon
    Image Credit & Copyright: Susan Snow

    Explanation: As you watched October's first Full Moon rise last night, the Full Moon closest to the northern autumnal equinox, you were probably asking yourself, "How long would it take to bike to the Moon?" Sure, Apollo 11 astronauts made the trip in 1969, from launch to Moon landing, in about 103 hours or 4.3 days. But the Moon is 400,000 kilometers away. This year, the top bike riders in planet Earth's well-known Tour de France race covered almost 3,500 kilometers in 21 stages after about 87 hours on the road. That gives an average speed of about 40 kilometers per hour and a lunar cycling travel time of 10,000 hours, a little over 416 days. While this bike rider's destination isn't clear, his journey did begin around moonrise on September 27 near Cleeve Hill, Bishops Cleeve, Cheltenham, UK.

    Tomorrow's picture: light-weekend


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    Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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  • Stephen Michael Kellat at 2020-09-12T16:05:24Z

    Got my shot Thursday.  I will be taking multiple family members through a drive-through event on Tuesday to get their shots.

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  • CERN experiments announce first indications of a rare Higgs boson process

    ParticleNews at 2020-08-03T17:28:47Z

    "CERN experiments announce first indications of a rare Higgs boson process"

    CERN experiments announce first indications of a rare Higgs boson processPress Releasexeno Mon, 08/03/2020 - 11:563120

    The ATLAS and CMS experiments at CERN have announced new results which show that the Higgs boson decays into two muons.

    dimuons

    Candidate event displays of a Higgs boson decaying into two muons as recorded by CMS (left) and ATLAS (right). (Image: CERN)

    Geneva. At the 40th ICHEP conference, the ATLAS and CMS experiments announced new results which show that the Higgs boson decays into two muons. The muon is a heavier copy of the electron, one of the elementary particles that constitute the matter content of the Universe. While electrons are classified as a first-generation particle, muons belong to the second generation. The physics process of the Higgs boson decaying into muons is a rare phenomenon as only about one Higgs boson in 5000 decays into muons. These new results have pivotal importance for fundamental physics because they indicate for the first time that the Higgs boson interacts with second-generation elementary particles.

    Physicists at CERN have been studying the Higgs boson since its discovery in 2012 in order to probe the properties of this very special particle. The Higgs boson, produced from proton collisions at the Large Hadron Collider, disintegrates – referred to as decay – almost instantaneously into other particles. One of the main methods of studying the Higgs boson’s properties is by analysing how it decays into the various fundamental particles and the rate of disintegration.

    CMS achieved evidence of this decay with 3 sigma, which means that the chance of seeing the Higgs boson decaying into a muon pair from statistical fluctuation is less than one in 700. ATLAS’s two-sigma result means the chances are one in 40. The combination of both results would increase the significance well above 3 sigma and provides strong evidence for the Higgs boson decay to two muons.

    “CMS is proud to have achieved this sensitivity to the decay of Higgs bosons to muons, and to show the first experimental evidence for this process. The Higgs boson seems to interact also with second-generation particles in agreement with the prediction of the Standard Model, a result that will be further refined with the data we expect to collect in the next run,” said Roberto Carlin, spokesperson for the CMS experiment.

    The Higgs boson is the quantum manifestation of the Higgs field, which gives mass to elementary particles it interacts with, via the Brout-Englert-Higgs mechanism. By measuring the rate at which the Higgs boson decays into different particles, physicists can infer the strength of their interaction with the Higgs field: the higher the rate of decay into a given particle, the stronger its interaction with the field. So far, the ATLAS and CMS experiments have observed the Higgs boson decays into different types of bosons such as W and Z, and heavier fermions such as tau leptons. The interaction with the heaviest quarks, the top and bottom, was measured in 2018. Muons are much lighter in comparison and their interaction with the Higgs field is weaker. Interactions between the Higgs boson and muons had, therefore, not previously been seen at the LHC.

    “This evidence of Higgs boson decays to second-generation matter particles complements a highly successful Run 2 Higgs physics programme. The measurements of the Higgs boson’s properties have reached a new stage in precision and rare decay modes can be addressed. These achievements rely on the large LHC dataset, the outstanding efficiency and performance of the ATLAS detector and the use of novel analysis techniques,” said Karl Jakobs, ATLAS spokesperson.

    What makes these studies even more challenging is that, at the LHC, for every predicted Higgs boson decaying to two muons, there are thousands of muon pairs produced through other processes that mimic the expected experimental signature. The characteristic signature of the Higgs boson’s decay to muons is a small excess of events that cluster near a muon-pair mass of 125 GeV, which is the mass of the Higgs boson. Isolating the Higgs boson to muon-pair interactions is no easy feat. To do so, both experiments measure the energy, momentum and angles of muon candidates from the Higgs boson’s decay. In addition, the sensitivity of the analyses was improved through methods such as sophisticated background modelling strategies and other advanced techniques such as machine-learning algorithms. CMS combined four separate analyses, each optimised to categorise physics events with possible signals of a specific Higgs boson production mode. ATLAS divided their events into 20 categories that targeted specific Higgs boson production modes.

    The results, which are so far consistent with the Standard Model predictions, used the full data set collected from the second run of the LHC. With more data to be recorded from the particle accelerator’s next run and with the High-Luminosity LHC, the ATLAS and CMS collaborations expect to reach the sensitivity (5 sigma) needed to establish the discovery of the Higgs boson decay to two muons and constrain possible theories of physics beyond the Standard Model that would affect this decay mode of the Higgs boson.


    LINKS

    Scientific materials
     
    Papers:
    CMS physics analysis summary: https://cds.cern.ch/record/2725423
    ATLAS paper on arXiv: https://arxiv.org/abs/2007.07830

    Physics briefings:
    CMS: https://cmsexperiment.web.cern.ch/news/cms-sees-evidence-higgs-boson-decaying-muons
    ATLAS: https://atlas.cern/updates/physics-briefing/new-search-rare-higgs-decays-muons

    Event displays and plots:
    CMS: https://cds.cern.ch/record/2720665?ln=en
     http://cds.cern.ch/record/2725728
    ATLAS: https://cds.cern.ch/record/2725717?ln=en
     https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2019-14

    Photos

    CMS detector:
    https://cds.cern.ch/record/1344500/files/0712017_02.jpg?subformat=icon-1440
    https://cds.cern.ch/record/1431473/files/bul-pho-2007-079.jpg?subformat=icon-1440

    ATLAS detector: https://mediastream.cern.ch/MediaArchive/Photo/Public/2007/0706038/0706038_02/0706038_02-A4-at-144-dpi.jpg
    https://mediastream.cern.ch/MediaArchive/Photo/Public/2007/0705021/0705021_01/0705021_01-A4-at-144-dpi.jpg

    CMS muon system:
    https://cds.cern.ch/record/2016944/files/IMG_0267.jpg?subformat=icon-1440
    https://cds.cern.ch/record/1431505/files/DSC_1432.jpg?subformat=icon-1440

    ATLAS muon spectrometer:
    https://mediastream.cern.ch/MediaArchive/Photo/Public/2006/0610010/0610010_02/0610010_02-A4-at-144-dpi.jpg
    https://mediastream.cern.ch/MediaArchive/Photo/Public/2007/0707043/0707043_01/0707043_01-A4-at-144-dpi.jpg

    CERN

    Joe Incandela, CERN spokesperson for Higgs Boson search update (Courtesy: Maximilien Brice, Laurent Egli)

    At CERN, the European Organization for Nuclear Research, physicists and engineers are probing the fundamental structure of the universe. They use the world's largest and most complex scientific instruments to study the basic constituents of matter – the fundamental particles. The particles are made to collide together at close to the speed of light. The process gives the physicists clues about how the particles interact, and provides insights into the fundamental laws of nature.

    Contact information
    European Organization for Nuclear Research
    CERN
    CH-1211 Genève 23
    Switzerland

    or

    Organisation Européenne pour
    la Recherche Nucléaire
    F-01631 CERN Cedex
    France
    + 41 22 76 761 11
    + 41 22 76 765 55 (fax)
     

    https://home.cern/

    Press Office

    Press@cern.ch
    +41 22 767 34 32
    +41 22 767 21 41

     

    https://www.interactions.org/press-release/cern-experiments-announce-first-indications-rare-higgs-boson

    ( Feed URL: http://www.interactions.org/index.rss )

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  • Astronomy Picture of the Day for 2020-07-27 12:30:02.271024

    Astronomy Picture of the Day (Unofficial) at 2020-07-27T17:30:02Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2020 July 27
    See Explanation.  Clicking on the picture will download
the highest resolution version available.

    Comet and Lightning Beyond Bighorn Mountains
    Image Credit & Copyright: Kevin Palmer

    Explanation: Normally, Steamboat Point looks cool -- but not this cool. Every day, the iconic peak of the Bighorn Mountains is an interesting sight, in particular from US Highway 14 in Wyoming. On some rare days, the rocky vertical ridges look even more incredible when seen in front of a distant lightning storm. Earlier this month, though, something even more unusual happened -- the naked-eye Comet NEOWISE rose above it in the middle of the night. Just as a distant lightning storm was occurring in the background. Recognizing a rare opportunity, a determined astrophotographer spent a sleepless night capturing over 1400 images of this unusual triple conjunction. The featured image is among the best of them, with the foreground lit by the Moon off to the right. Comet C/2020 F3 (NEOWISE) is now headed back to the outer Solar System, destined to return only in about 6700 years.

    Comet NEOWISE Images: July 26 || 25 || 24 || 23 || 22 || 21 || 20 || 19 || 18 || 17 || 16 || 15 || 14 || 13 || 12 || 11 || 10 & earlier ||
    Tomorrow's picture: fighting space dragons


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    Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
    NASA Official: Phillip Newman Specific rights apply.
    NASA Web Privacy Policy and Important Notices
    A service of: ASD at NASA / GSFC
    & Michigan Tech. U.

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  • Astronomy Picture of the Day for 2020-07-22 12:30:02.495176

    Astronomy Picture of the Day (Unofficial) at 2020-07-22T17:30:03Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2020 July 22
    See Explanation.  Clicking on the picture will download
the highest resolution version available.

    The Structured Tails of Comet NEOWISE
    Image Credit & Copyright: Zixuan Lin (Beijing Normal U.)

    Explanation: What is creating the structure in Comet NEOWISE's tails? Of the two tails evident, the blue ion tail on the left points directly away from the Sun and is pushed out by the flowing and charged solar wind. Structure in the ion tail comes from different rates of expelled blue-glowing ions from the comet's nucleus, as well as the always complex and continually changing structure of our Sun's wind. Most unusual for Comet C/2020 F3 (NEOWISE), though, is the wavy structure of its dust tail. This dust tail is pushed out by sunlight, but curves as heavier dust particles are better able to resist this light pressure and continue along a solar orbit. Comet NEOWISE's impressive dust-tail striations are not fully understood, as yet, but likely related to rotating streams of sun-reflecting grit liberated by ice melting on its 5-kilometer wide nucleus. The featured 40-image conglomerate, digitally enhanced, was captured three days ago through the dark skies of the Gobi Desert in Inner Mongolia, China. Comet NEOWISE will make it closest pass to the Earth tomorrow as it moves out from the Sun. The comet, already fading but still visible to the unaided eye, should fade more rapidly as it recedes from the Earth.

    Notable NEOWISE Images Submitted to APOD: July 21 || 20 || 19 || 18 || 17 || 16 || 15 || 14 || 13 || 12 || 11 || 10 & earlier ||
    Tomorrow's picture: open space


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    Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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  • More than 3000 scientists gather online for Neutrino 2020

    ParticleNews at 2020-07-13T21:28:08Z

    "More than 3000 scientists gather online for Neutrino 2020"

    A dash of virtual reality helps replicate the serendipitous interactions of an in-person conference when participants are scattered across the globe.

    Virtual enter here sign

    Physics poster sessions: a heady mix of science, networking and robots. That last one isn’t so common at in-person science conferences, but it was a regular sight at the recently concluded Neutrino 2020 conference, where virtual reality poster sessions hosted thousands of robotic avatars belonging to particle physicists from around the world. While most walked through the virtual world as a robot in vaguely human clothing, others donned panda suits, uploaded custom skins with gigantic human heads or particle tracks or—in one case—turned themselves into a jar of Jif peanut butter.

    “It’s both more weird and more fun than I expected,” says Diana Parno, a physicist at Carnegie Mellon University who presented in one of the virtual poster sessions. “And one of the nice things about poster sessions is meeting with new people and colleagues, and making introductions—and we’ve still been able to do that.”

    The 29th International Conference on Neutrino Physics is the largest gathering of neutrino scientists in the world. This year the conference was hosted jointly by the Department of Energy’s Fermilab and the University of Minnesota and, for the first time, held entirely online. The change brought many advantages to the conference. Notably, more than 3400 people from 67 countries and covering all seven continents tuned in to the 79 talks – more than four times the typical number of attendees. (Almost half of attendees were early in their career, identifying as undergraduate or graduate students.) Instead of full days of talks, half-days were spread over two weeks, allowing greater involvement from participants in different time zones. Going virtual also meant some individuals with monetary restrictions, travel restrictions, or obligations at home or work could participate.

    The decision to move online about two months before the event also brought challenges. Organizers were faced with quickly transitioning one of the most valuable parts of the conference: the networking, serendipitous interactions and other engagement that happens outside of the scheduled talks. That’s where virtual reality poster sessions came in.

    “What we really wanted from this platform is a way for people to interact with others as if they were in person,” says Marco Del Tutto, a Fermilab physicist who created the virtual poster sessions using open source software from Mozilla Hubs. “It’s hard to tell if this is going to work until you try. It made me proud when I went into a poster session and saw people explaining their poster to a crowd, or walking through a room and running into people.”

    Over the course of four sessions, presenters showed off 532 posters on display in 30 different virtual reality rooms. (A standard list of posters and short videos from the presenters were also available on a webpage). While in-person posters are typically set up in one concentrated area, spreading the posters across virtual rooms gave avatars more space – and reduced the amount of bandwidth to run each interactive area. It also gave Del Tutto a chance to add a neutrino twist. Four different styles of room represented four different sources of neutrinos: Fermilab’s iconic bison and Wilson Hall were the backdrop for accelerator neutrinos, a nuclear power plant represented reactor neutrinos, an enormous sun hung low in the sky for solar neutrinos and an exploding star overhead for supernova neutrinos. To complete the conference vibe, there were tables, couches and cookies scattered around.

    Participants could talk in real time, their avatars’ heads rapidly bouncing around. Directional sound in headphones gave a sense of where different people were in the room and allowed users to stumble upon conversations. Walking around, one overheard all the usual topics of discussion at a physics conference—results, experimental status, careers, life updates—as well as discussion of the oddities of virtual environment—the digital bison standing nearby, how to make your avatar wear a tuxedo, the underlying technology and the inevitable glitch here or there.

    “It’s clearly the kind of thing that will get better and better,” says Kate Scholberg, a neutrino physicist at Duke University and a member of the International Advisory Committee for the conference. She also gathered together about 20 members of the COHERENT collaboration for an avatar group photo in Grant Park. “It’s different, and I think it’s been really fun. I’ve been having conversations with people, and it replicates many of the in-person aspects.”

    Del Tutto and the organizers also set up social rooms for researchers to hang out and chat, as well as virtual tours of Fermilab locations and spots in downtown Chicago.

    “The other part of a conference is that, if it’s really in Chicago, it’s a chance to see the city with your colleagues, get to know them better and improve your working relationship with them,” Del Tutto says.

    Of course, virtual reality was not the only way to interact with colleagues. Attendees also connected through chat on a dedicated Neutrino 2020 Slack account. Organizers set up channels for subsets of neutrino research (such as sterile neutrinos or long-baseline neutrinos) where attendees could drop in additional questions for the speakers and discuss ideas from the talks. There were also specific channels for topics such as the future of conferences, posters, help from the organizers, virtual reality and job opportunities. The Neutrino 2020 Slack saw more than 23,000 messages over the two-week conference.

    “We had to change our plans quickly and explore creative options for making the conference as interactive as possible,” says Tanaz Mohayai, a Fermilab neutrino physicist and the webpage lead for Neutrino 2020. “It’s been wonderful to see the excitement surrounding the latest results in our field, as well as the many meaningful conversations taking place on Slack and in the poster sessions in the virtual world.”

    Many attendees expect to see the virtual reality and chat features of Neutrino 2020 replicated in future online physics conferences – but it may not stop there. As conferences return to having an in-person component, there’s potential to keep the best of what works from the online world. One can envision a hybrid conference that allows for participation from around the world, virtual interactions and greater discussion through chat. And maybe, just maybe, there will be people walking around poster sessions dressed as robots—or a jar of peanut butter.

    The poster portal, videos and recordings of plenary talks will continue to be available online at the Neutrino 2020 website.

    Editor's note: A version of this article was previously published by Fermilab.

    https://www.symmetrymagazine.org/article/more-than-3000-scientists-gather-online-for-neutrino-2020?utm_source=main_feed_click&utm_medium=rss&utm_campaign=main_feed&utm_content=click

    ( Feed URL: http://www.symmetrymagazine.org/feed )

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  • Stephen Michael Kellat at 2020-07-11T00:30:45Z

    According to the Commission, those call letters have been assigned to a station since 1974 at Missouri State University.  KPNI were also call letters associated with a station there.

    Usually FM stations at academic institutions go off the air due to money issues.  Maintaining them is not cheap.  Compliance costs keep increasing.  The time of 2003 is roughly a point when multiple academic institutions surrendered station licenses to the Commission in favor of switching to webcasting for practical training for their journalism and communications students.

    The station was low enough profile that WTFDA has no readily accessible references to it. 

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  • Astronomy Picture of the Day for 2020-07-09 12:30:02.152445

    Astronomy Picture of the Day (Unofficial) at 2020-07-09T17:30:03Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2020 July 9
    See Explanation.  Clicking on the picture will download
the highest resolution version available.

    Noctilucent Clouds and Comet NEOWISE
    Image Credit & Copyright: Emmanuel Paoly

    Explanation: These silvery blue waves washing over a tree-lined horizon in the eastern French Alps are noctilucent clouds. From high in planet Earth's mesosphere, they reflect sunlight in this predawn skyscape taken on July 8. This summer, the night-shining clouds are not new to the northern high-latitudes. Comet NEOWISE is though. Also known as C/2020 F3, the comet was discovered in March by the Earth-orbiting Near Earth Object Wide-field Infrared Survey Explorer (NEOWISE) satellite. It's now emerging in morning twilight only just visible to the unaided eye from a clear location above the northeastern horizon.

    Tomorrow's picture: pixels in space


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    Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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  • Stephen Michael Kellat at 2020-07-06T13:18:32Z

    The responsible thing the Ohio General Assembly could do would be to shutter campuses now.  Unfortunately we are going half speed ahead on re-opening with plans to fall down to online-only if things get bad.School districts are insisting on “local control” and Ashtabula Area City Schools is horrifyingly insisting on 5 days a week back in the classroom for every child.

    There are procedures for removing elected officials in Ohio for malfeasance, misfeasance, nonfeasance, and drunkenness that don’t require recall elections.  I’m not sure I’m ready to dig into those.  Too many people think locally that coronavirus doesn’t really exist and won’t impact them so I might not get the support needed to push for removing the school board’s membership. 

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  • Covid-19: why R is a lot more complicated than you think

    PumpCast at 2020-06-30T04:13:40Z

    "Covid-19: why R is a lot more complicated than you think"

    Over the last few months, we’ve all had to come to terms with R, the ‘effective reproduction number’, as a measure of how well we are dealing with the coronavirus outbreak. But, as Nicola Davis finds out from Dr Adam Kucharski, R is a complicated statistical concept that relies on many factors and, under some conditions, can be misleading. Help support our independent journalism at theguardian.com/sciencepod

    https://www.theguardian.com/science/series/science/5ef9e1ff8f08d1a09fd4f1f6

    ( Feed URL: https://www.theguardian.com/science/series/science/podcast.xml )

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  • Astronomy Picture of the Day for 2020-06-27 12:30:02.231108

    Astronomy Picture of the Day (Unofficial) at 2020-06-27T17:30:03Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2020 June 27
    See Explanation.  Clicking on the picture will download
the highest resolution version available.

    Eclipse under the ISS
    Image Credit: NASA ISS Expedition 63

    Explanation: The dark shadow of the New Moon reached out and touched planet Earth on June 21. A high definition camera outside the International Space Station captured its passing in this snapshot from low Earth orbit near the border of Kazakhstan and China. Of course those along the Moon's central shadow track below could watch the much anticipated annular eclipse of the Sun. In the foreground a cargo spacecraft is docked with the orbital outpost. It's the H-II Transfer Vehicle-9 from JAXA the Japan Aerospace Exploration Agency.

    Gallery: Notable images of the Annular Solar Eclipse of 2020 June submitted to APOD
    Tomorrow's picture: moons and shadows


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    Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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  • SuperKEKB collider achieves the world's highest luminosity

    ParticleNews at 2020-06-26T14:28:48Z

    "SuperKEKB collider achieves the world's highest luminosity"

    SuperKEKB collider achieves the world's highest luminosityPress Releasexeno Fri, 06/26/2020 - 08:252920

    Fig. 1 The instantaneous luminosity of SuperKEKB measured at 5-minute intervals from Fall 2019 to June 22, 2020. Values are on-line measurements and contain an approximate 1% error.

    Fig. 1 The instantaneous luminosity of SuperKEKB measured at 5-minute intervals from Fall 2019 to June 22, 2020. Values are on-line measurements and contain an approximate 1% error.

    Japan’s High Energy Accelerator Research Organization (KEK) has been steadily improving the performance of its flagship electron-positron collider, SuperKEKB, since it produced its first electron-positron collisions in April 2018. At 20:34 on 15th June 2020, SuperKEKB achieved the world’s highest instantaneous luminosity for a colliding-beam accelerator, setting a record of 2.22×1034cm-2s-1. Previously, the KEKB collider, which was SuperKEKB’s predecessor and was operated by KEK from 1999 to 2010, had achieved the world’s highest luminosity, reaching 2.11×1034cm-2s-1. KEKB’s record was surpassed in 2018, when the LHC proton-proton collider at the European Organization for Nuclear Research (CERN) overtook the KEKB luminosity at 2.14×1034cm-2s-1. SuperKEKB’s recent achievement returns the title of world’s highest luminosity colliding-beam accelerator to KEK.(*)

    (*)The current record is 2.40×1034cm-2s-1, obtained at 00:53 JST on June 21st.

    In the coming years, the luminosity of SuperKEKB will be increased to approximately 40 times the new record. This exceptionally high luminosity is to be achieved mainly by using a beam collision method called the “nano-beam scheme”, developed by Italian physicist Pantaleo Raimondi. Raimondi’s innovation enables significant increases in luminosity by using powerful magnets to squeeze the two beams in both the horizontal and vertical directions. Substantially decreasing the beam sizes increases the luminosity, which varies inversely with the cross-sectional area of the colliding beams.

    SuperKEKB is the first collider in the world to realize the nano-beam scheme. In the beam operation of SuperKEKB, we keep increasing the luminosity by squeezing the beams ever harder, while solving various problems associated with the squeezing. Currently, the vertical height of the beams at the collision point is about 220 nanometers, and this will decrease to approximately 50 nanometers (about 1/1000 the width of a human hair) in the future.

    Another factor that determines luminosity is the product of the two beam currents, which is proportional to the product of the numbers of electrons and positrons stored in the collider. KEK physicists and accelerator operators continue to increase the beam currents, while mitigating various high-current problems, such as stray background particles that introduce noise in the Belle II detector. SuperKEKB achieved the new luminosity record with a product of beam currents that was less than 25% that of KEKB. This demonstrates the superiority of the SuperKEKB design. In the future, we aim to increase the beam current product to about four times the value achieved by KEKB.

    In order to adopt the nano-beam scheme and increase the beam current, KEKB underwent significant upgrades that turned it into SuperKEKB. These included a new beam pipe, new superconducting final-focusing magnets, a positron damping ring, and an advanced injector. The most recent improvement was completed in April 2020, with the introduction of the “crab waist”, first used at the DAΦNE accelerator in Frascati, Italy, in 2010, and which reduces the beam size and stabilizes collisions.

    The success of SuperKEKB relies also on contributions from overseas. As an example, the superconducting final-focusing magnets were built in cooperation with Brookhaven National Laboratory and Fermi National Accelerator Laboratory in the U.S. under the U.S.-Japan Science and Technology Cooperation Program. Other major contributions under this program were the development of a collision-point orbit feedback system (SLAC National Accelerator Laboratory) and an X-ray beam size monitor (University of Hawaii and SLAC National Accelerator Laboratory). Researchers from CERN (Switzerland), IJCLab (France), IHEP (China)as well as SLAC(U.S.) have participated in accelerator research and operation under KEK’s Multinational Partnership Project (MNPP-01).There are also contributions from many other foreign research institutes. Other important contributions have come through the Belle II experiment collaboration, such as the diamond-based radiation monitor and beam abort system (INFN and University of Trieste, Italy), and the luminosity monitoring system developed at BINP (Russia).

    SuperKEKB brings its electron and positron beams into collision at the center of the Belle II particle detector. The detector has been built and is operated by the Belle II collaboration, an international group of approximately 1,000 physicists and engineers from 119 universities and laboratories located in 26 countries and regions around the world. Belle II physicists use the detector to explore fundamental physics phenomena, by studying the production and decay processes of particles produced in the collisions, primarily B mesons, D mesons, and tau leptons. To within the precision of current measurements, the behavior of particles such as these is well described by the theory known as the Standard Model. However, the Standard Model fails to address key questions, such as the mystery of the matter-dominated universe and the existence of dark matter. Therefore, new physical laws are needed to explain these observations. Signals of such “new physics” may arise in decay processes that are very rarely observed. Maximizing the discovery potential of Belle II for such signals requires a large number of electron-positron collisions, necessitating a very high-luminosity collider, such as SuperKEKB.

    Collecting data for about 10 years, the Belle II experiment will accumulate 50 times more particle collisions than its predecessor, the Belle experiment. The large data set, containing about 50 billion B-meson pairs and similar numbers of charm mesons and tau leptons, will enable Belle II physicists to explore nature at a much deeper level than was previously possible. The data will also be used in sensitive searches for very weakly interacting particles that may help answer some of the outstanding mysteries of the universe.

    kekfig2

    Collaborators rejoicing over the world record (Image Credit: KEK)

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    High Energy Accelerator Research Organization (KEK)

    Render of International Linear Collider - Next-generation particle accelerator (Courtesy: Rey.Hori/KEK)

    KEK was established in 1997 in a reorganization of the Institute of Nuclear Study, University of Tokyo (established in 1955), the National Laboratory for High Energy Physics (established in 1971), and the Meson Science Laboratory of the University of Tokyo (established in 1988).

    Scientists at KEK use accelerators and perform research in high-energy physics to answer the most basic questions about the universe as a whole, and the matter and the life it contains.

     

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  • Astronomy Picture of the Day for 2020-06-26 12:30:02.216158

    Astronomy Picture of the Day (Unofficial) at 2020-06-26T17:30:02Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2020 June 26
    See Explanation.  Clicking on the picture will download
the highest resolution version available.

    Eclipse under the Bamboo
    Image Credit & Copyright: Somak Raychaudhury (Inter-University Centre for Astronomy & Astrophysics)

    Explanation: Want to watch a solar eclipse safely? Try looking down instead of up, though you might discover you have a plethora of images to choose from. For example, during the June 21st solar eclipse this confusing display appeared under a shady bamboo grove in Pune, India. Small gaps between close knit leaves on the tall plants effectively created a network of randomly placed pinholes. Each one projected a separate image of the eclipsed Sun. The snapshot was taken close to the time of maximum eclipse in Pune when the Moon covered about 60 percent of the Sun's diameter. But an annular eclipse, the Moon in silhouette completely surrounded by a bright solar disk at maximum, could be seen along a narrow path where the Moon's dark shadow crossed central Africa, south Asia, and China.

    Gallery: Notable images of the Annular Solar Eclipse of 2020 June submitted to APOD
    Tomorrow's picture: pixels in space


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    Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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  • DUNE moves to the next stage with a blast

    ParticleNews at 2020-06-24T21:29:00Z

    "DUNE moves to the next stage with a blast"

    Construction workers have carried out the first underground blasting for the Long-Baseline Neutrino Facility, which will provide the space, infrastructure and particle beam for the international Deep Underground Neutrino Experiment. 

    Two construction workers in a tunnel below ground

    It started with a blast.

    On June 23, construction company Kiewit Alberici Joint Venture set off explosives 3,650 feet beneath the surface in Lead, South Dakota, to begin creating space for the international Deep Underground Neutrino Experiment, hosted by the Department of Energy’s Fermilab.

    The blast is the start of underground excavation activity for the experiment, known as DUNE, and the infrastructure that powers and houses it, called the Long-Baseline Neutrino Facility, or LBNF.

    Situated a mile deep in South Dakota rock at the Sanford Underground Research Facility, DUNE’s giant particle detector will track the behavior of fleeting particles called neutrinos. The plan for the next three years, is that workers will blast and drill to remove 800,000 tons of rock to make a home for the gigantic detector and its support systems.

    “The start of underground blasting for these early excavation activities marks not only the initiation of the next major phase of this work, but significant progress on the construction already under way to prepare the site for the experiment,” says Fermilab Deputy Director for LBNF/DUNE-US Chris Mossey.

    The excavation work begins with removing 3,000 tons of rock 3,650 feet below ground. This initial step carves out a station for a massive drill whose bore is as wide as a car is long, about four meters.

    The machine will help create a 1,200-foot ventilation shaft down to what will be the much larger cavern for the DUNE particle detector and associated infrastructure. There, 4,850 feet below the surface—about 1.5 kilometers deep—the LBNF project will remove hundreds of thousands of tons of rock, roughly the weight of eight aircraft carriers.

    The emptied space will eventually be filled with DUNE’s enormous and sophisticated detector, a neutrino hunter looking for interactions from one of the universe’s most elusive particles. Researchers will send an intense beam of neutrinos from Fermilab in Illinois to the underground detector in South Dakota—straight through the earth, no tunnel necessary—and measure how the particles change their identities. What they learn may answer one of the biggest questions in physics: Why does matter exist instead of nothing at all?

    “The worldwide particle physics community is preparing in various ways for the day DUNE comes online, and this week, we take the material step of excavating rock to support the detector,” says DUNE co-spokesperson Stefan Söldner-Rembold of the University of Manchester. “It’s a wonderful example of collaboration: While excavation takes place in South Dakota, DUNE partners around the globe are designing and building the parts for the DUNE detector.”

    A number of science experiments already take data at Sanford Underground Research Facility, but no activity takes place at the 3650 level. With nothing and no one in the vicinity, the initial excavation stage to create the cavern for the drill proceeds in an isolated environment. It’s also an opportunity for the LBNF construction project to gather information about matters such as air flow and the rock’s particular response to the drill-and-blast technique before moving on to the larger excavation at the 4850 level, where the experiment will be built.

    “It was important for us to develop a plan that would allow the LBNF excavation to go forward without disrupting the experiments already going on in other parts of the 4850 level,” says Fermilab Long-Baseline Neutrino Facility Far-Site Conventional Facilities Manager Joshua Willhite. Following a period of excavation at the 3650 level, the project will initiate excavation at the 4850 level.

    Every bit of the 800,000 tons of rock dislodged by the underground drill-and-blast operation must eventually be transported a mile back up to the surface. There, a conveyor is being built to transport the crushed rock over a stretch of 4,200 feet for final deposit in the Open Cut, an enormous open pit mining area excavated in the 1980s. As large as the LBNF excavation will be, the rock moved to the surface and deposited in the Open Cut will only fill less than one percent of it.

    Excavation at the 3650 level will be completed over the next few months, with blasting at the 4850 level planned to begin immediately after.

    Editor's note: A version of this article was originally published by Fermilab.

    https://www.symmetrymagazine.org/article/DUNE-moves-to-the-next-stage-with-a-blast?utm_source=main_feed_click&utm_medium=rss&utm_campaign=main_feed&utm_content=click

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  • Astronomy Picture of the Day for 2020-06-20 12:30:02.209075

    Astronomy Picture of the Day (Unofficial) at 2020-06-20T17:30:02Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2020 June 20
    See Explanation.  Clicking on the picture will download
the highest resolution version available.

    Northern Summer on Titan
    Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA

    Explanation: Today's solstice brings summer to planet Earth's northern hemisphere. But the northern summer solstice arrived for ringed planet Saturn over three years ago on May 24, 2017. Orbiting the gas giant, Saturn's moon Titan experiences the Saturnian seasons that are about 7 Earth-years long. Larger than inner planet Mercury, Titan was captured in this Cassini spacecraft image about two weeks after its northern summer began. The near-infrared view finds bright methane clouds drifting through Titan's dense, hazy atmosphere as seen from a distance of about 507,000 kilometers. Below the clouds, dark hydrocarbon lakes sprawl near its fully illuminated north pole.

    Tomorrow's picture: Venus by moonlight


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    Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
    NASA Official: Phillip Newman Specific rights apply.
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    & Michigan Tech. U.

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  • Astronomy Picture of the Day for 2020-06-17 12:30:01.518292

    Astronomy Picture of the Day (Unofficial) at 2020-06-17T17:30:02Z

    Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

    2020 June 17
    See Explanation.  Clicking on the picture will download
the highest resolution version available.

    Magnetic Streamlines of the Milky Way
    Image Credit: ESA, Planck; Text: Joan Schmelz (USRA)

    Explanation: What role do magnetic fields play in interstellar physics? Analyses of observations by ESA's Planck satellite of emission by small magnetically-aligned dust grains reveal previously unknown magnetic field structures in our Milky Way Galaxy -- as shown by the curvy lines in the featured full-sky image. The dark red shows the plane of the Milky Way, where the concentration of dust is the highest. The huge arches above the plane are likely remnants of past explosive events from our Galaxy's core, conceptually similar to magnetic loop-like structures seen in our Sun's atmosphere. The curvy streamlines align with interstellar filaments of neutral hydrogen gas and provide tantalizing evidence that magnetic fields may supplement gravity in not only in shaping the interstellar medium, but in forming stars. How magnetism affected our Galaxy's evolution will likely remain a topic of research for years to come.

    Tomorrow's picture: open space


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  • The stories a muon could tell

    ParticleNews at 2020-06-16T20:28:06Z

    "The stories a muon could tell"

    The discovery of the muon originally confounded physicists. Today international experiments are using the previously perplexing particle to gain a new understanding of our world.

    Illustration of the earth taking a shower

    At the beginning of the 20th century, physicists were aware of a pervasive shower of particles that seemed to rain down from space. By filling glass chambers with highly condensed vapor, they could indirectly see tracks left by these highly energetic particles now known as cosmic rays. In doing so, they quickly discovered the subatomic world was more complex than initially suspected. 

    The first new matter particle they discovered was the muon. It was a lot like an electron, just more massive. At first, no one knew what to make of it. 

    Some thought it might be a particle theorized to hold protons and neutrons together in an atom. But a pair of Italians conducting experiments in Rome during World War II proved otherwise. 

    After discarding a few alternative theories—including one that posited that this particle might be a new kind of electron—physicists were left with one conclusion: They had discovered a particle that nobody had predicted. As Nobel Laureate I.I. Rabi famously quipped, “Who ordered that?”

    Although scientists hadn’t realized muons would be on the menu, the discovery of muons eventually led to a discovery about how that menu was set up: Particles can come in different versions, each alike in charge, spin and interactions but different in mass. The muon, for example, has the same charge, spin and electroweak interactions as the electron, but is about 200 times heavier, and there’s an even heavier version of the electron and muon, called the tau.  

    Physicists built on this principle to predict the existence of generations of other particles, such as neutrinos, which with electrons, muons and taus round out the set of particles called leptons. Eventually, scientists would find that all of the matter particles in the Standard Model, including quarks, could be organized into three generations, though only the lightest are stable. 

    Muons continue to be useful tools for discovery to this day. Two international experiments, one currently underway and the other slated to begin in the early 2020s, are using the previously perplexing particles to push the boundaries of physics.

    Flavor physics and the Mu2e experiment

    Each of the three generations is called a different “flavor” of particle. 

    At first, scientists assumed that flavor was a property that, like mass or energy, had to be conserved when particles interacted with each other. That wasn’t quite right, but in their defense, they did find this to be true almost all of the time.

    “When you have some kind of an interaction that involves charged leptons, such as nuclear or particle decay or some type of high-energy particle interaction, the number of a given flavor of charged leptons remains the same,” says Jim Miller, a professor of physics at Boston University. 

    When muons decay, for example, they transform into an electron, an anti-electron neutrino, and a muon neutrino. The electron and anti-electron neutrino cancel each other out, flavor-wise, leaving just the muon neutrino, which has the same flavor as the original muon.

    Flavor conservation was useful; it allowed physicists to predict the interactions they would observe in particle accelerators and nuclear reactions. And those predictions proved to be correct. 

    But then physicists discovered that the group of (uncharged lepton) particles called neutrinos are unaware they are expected to follow the rules. On their long journey to Earth from the center of the sun, where they are created in fusion reactions, neutrinos freely oscillate between generations, transforming from electron neutrinos to muon neutrinos to tau neutrinos and back without releasing any additional particles.

    This phenomenon, which won researchers Takaaki Kajita and Arthur B. McDonald the Nobel Prize for Physics in 2015, left scientists with a question: If neutrinos could violate flavor conservation, could other particles do it, too?

    Physicists hope to answer that exact question with Mu2e, an experiment scheduled to start generating data in the next few years at the US Department of Energy’s Fermi National Accelerator Laboratory. The experiment is supported by funding from DOE’s Office of Science. 

    Mu2e will search for muons converting into electrons without releasing other particles, a process that would clearly violate flavor conservation. 

    But why use muons? It’s because they’re the just-right middle of the lepton family. Not too big or too small, muons are a sort of Goldilocks particle that are perfectly suited to aid physicists in their search for new physics.

    Electrons, the least massive charged leptons, are small and stable. Taus, the most massive ones, are so massive and short-lived that they decay far too quickly for physicists to effectively study. Muons, however, are massive enough to decay but not massive enough to decay too quickly, making them the perfect tool in the search for new physics.

    In the Mu2e experiment, physicists will accelerate a beam of low-energy muons toward a target made of aluminum. In the resulting collisions, muons will knock electrons out of their orbits around the aluminum nuclei and take their place, creating muonic atoms for a brief moment in time.

    “Since the mass of the muon is 200 times greater than the mass of the electron, and its average distance from the nucleus is 200 times smaller, there’s an overlap between the muon’s position and the position of the aluminum nucleus, allowing them to interact,” Miller says.

    As the muon decays into an electron, physicists predict that the extra energy that usually goes into creating two neutrinos in a typical muon decay will instead be transferred to the atom’s nucleus. This would allow the conversion from one flavor to another, muon to electron, without any neutrinos or antineutrinos to provide balance. If observed, this direct transition of a muon into an electron would be the hoped-for discovery of flavor violation among charged leptons.

    Magnetic moment of fame

    Mu2e is not the only experiment that will use muons to test our understanding of physics.

    Eight years before the discovery of muons, physicist Paul Dirac was developing a theory to describe the motion of electrons. In a single, elegant equation, Dirac successfully described that motion—while simultaneously merging Albert Einstein’s special theory of relativity with quantum mechanics and predicting the existence of antimatter. 

    It’s hard to overstate how important and incredibly accurate Dirac’s equation turned out to be. Physicists still act giddy whenever it’s mentioned. 

    To understand why it’s important, take a look at the electron.

    Dirac’s equation correctly described exactly how the electromagnetic force worked and gave the correct estimate for how an electron’s spin would shift—or “precess”—if placed in a magnetic field, a measurement known as g. (That prediction was later refined through calculations from the field of quantum electrodynamics.)

    When muons were discovered in 1936, Dirac’s equation was used to calculate what their precession rate would be as well. The value g for muons was predicted to be equal to 2. 

    But when physicists began generating muons in accelerators at CERN in the 1950s to test his predictions, the results were not quite what they expected. Had they found a discrepancy between observation and theory? Although physicists worked hard for the next 20 years, they couldn’t generate enough energy with their accelerators to obtain a conclusive answer.

    Scientists at Brookhaven National Laboratory were able to test Dirac’s prediction at higher energies between 1999 and 2001 with an experiment meant to directly determine the anomalous part of the magnetic moment called Muon g-2 (pronounced “Muon g minus 2”). They found hints of the same anomalous measurement, but even with their improved technology, they lacked sufficient precision to prove a disagreement with theory.

    Could Dirac’s equation turn out to be wrong? Physicists think it could be that their findings in muons are actually hinting at a deeper structure in physics that has yet to be discovered and that studying muons could once again lead to new revelations.

    “The g-2 factor has been measured for other particles,” says Fermilab physicist Tammy Walton.  “It’s been very precisely measured for the electron. It’s also been measured for composite particles, like the proton and neutron. But the large mass of muons make them more sensitive to new physics.”

    Fermilab recently began the next generation Muon g-2 experiment, which physicists hope along with J-PARC in Japan will unequivocally confirm whether or not theory agrees with nature. Funded by the DOE's Office of Science, the experiment at Fermilab has been taking data since 2017.

    “We hope to get 20 times the number of muons, giving us a fourfold reduction in statistical uncertainty,” says Erik Swanson, a research engineer at the University of Washington. “If our central value stays the same as that generated at Brookhaven, then we will have confirmed without a doubt the discrepancy between theory and observation. Otherwise it might just be that theory was right all along.”

    If the theory is broken, physicists will have a lot of explaining to do, which could lead them to a new understanding of the particles and forces that make up our universe and the forces that govern them. Not bad work for a particle nobody ordered.

    https://www.symmetrymagazine.org/article/the-stories-a-muon-could-tell?utm_source=main_feed_click&utm_medium=rss&utm_campaign=main_feed&utm_content=click

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  • Search for new physics through multiboson production

    ParticleNews at 2020-06-11T14:28:35Z

    "Search for new physics through multiboson production"

    Search for new physics through multiboson production cagrigor Wed, 06/10/2020 - 12:21

    Search for new physics through multiboson production
    (Image: CERN)

    This media update is part of a series related to the 2020 Large Hadron Collider Physics conference, which took place from 25 to 30 May 2020. Originally planned to take place in Paris, the conference was held entirely online due to the COVID-19 pandemic.

    At the LHCP conference this year, the ATLAS and CMS collaborations presented new results relating to a physics process called vector boson scattering. CMS also reported the first observation of the so-called “massive triboson production. Studying these processes to test the Standard Model is important as it could shed light on new physics. The results were presented online at the virtual LHCP conference, originally due to be held in Paris.

    During proton collisions at the LHC, many particles, including the carriers of the electroweak force – photons and W and Z bosons – are produced. These bosons are often referred to simply as vector bosons, in the Standard Model, and one of the processes that leads to their pair production is called vector boson scattering.

    Vector boson processes are an excellent probe to seek deviation from theoretical predictions. Two rare processes that are of particular interest as they probe the self-interactions of four vector bosons are diboson production via vector boson scattering and triboson production”. The observation and measurement of these processes are important as they test the electroweak symmetry breaking mechanism, whereby the unified electroweak force separates into electromagnetic and weak forces in the Standard Model, and are complementary to the measurements of Higgs boson production and decay.

    In a vector boson scattering process, a vector boson is radiated from a quark in each proton and these vector bosons scatter off one another to produce a diboson final state. Triboson production refers instead to the production of three massive vector bosons.

    At the LHCP conference, physicists from the ATLAS and CMS collaborations presented new searches for the production of a pair of Z bosons via electroweak production including the vector boson scattering mechanism. ATLAS observed this process at 5.5 sigma and CMS reported strong evidence. CMS also reported the first observation of a W boson produced in association with a photon through the vector boson scattering process, as well as more precise measurements of the same-sign WW production, and an observation of the vector boson scattering production of a W and a Z boson, complementing earlier ATLAS observations.

    Another way to probe four-boson interaction is to study the very rare production of three massive bosons or tribosons. This April, the CMS experiment released a 5.7 sigma result of the triboson phenomenon, establishing it as a firm observation, following the first evidence of this process seen by the ATLAS experiment last year.

    Most physics processes of fundamental particles involve two or more individual particles that interact with each other via an intermediary particle that is emitted or absorbed in the process.

    “The more bosons produced, the rarer the event. This new observation of tribosons was very difficult because it is a much rarer process than the one that led to the Higgs boson discovery, and very interesting because it may reveal signs of new particles and anomalous interactions,” says Roberto Carlin, CMS spokesperson.

    In the triboson and vector boson scattering processes, W and Z can interact with themselves to create more W and Z particles, producing two or three bosons. W and Z being highly unstable particles, they quickly decay into leptons (electrons, muons, taus and their corresponding neutrinos) or quarks. But such processes are extremely rare and the diboson and triboson events that physicists look for are mimicked by background processes, making them even more difficult for physicists to analyse.

    “To separate signal from background, physicists have to be ingenious and employ advanced machine learning algorithms. This is a challenging task for such rare processes, and requires meticulous and thorough studies,” says Karl Jakobs, ATLAS spokesperson.

    The measurements of vector boson scattering and triboson production presented at LHCP 2020 are consistent with the predictions made by the Standard Model, which remains our best understanding of fundamental particles and their interactions. The above observations also provide physicists with tools to probe quartic self-interaction between massive electroweak bosons. The current measurements place constraints on the strength at which these quartic interactions take place and increased precision from the use of new datasets could open up horizons for new physics at higher energy scales in the LHC and lead to possible discoveries of new particles.

    https://home.cern/news/news/physics/search-new-physics-through-multiboson-production

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