Three cousins join family of four-quark particles

Three cousins join family of four-quark particles

Large Hadron Collider finds heavier versions of strange-charm combinations

Large Hadron Collider LHCb

QUARK QUARTET FINDER  Scientists with the Large Hadron Collider’s LHCb experiment (shown) have found a family of four particles made up of four quarks each.

CERN

An exotic particle now has three new cousins, making for a happy family of four.

Scientists with the LHCb experiment, located at the Large Hadron Collider near Geneva, announced the discovery of the particle’s new cousins in two papers published online at arXiv.org on June 25. The particles are each made up of four quarks, elementary particles known for their role as the building blocks of protons and neutrons.

The previously known particle, X(4140), and its cousins —  X(4274), X(4500) and X(4700) — are composed of two charm quarks and two strange quarks. Each particle’s quarks are arranged in configurations of increasingly higher energy, making each particle heftier than the last — thanks to the equivalence of mass and energy expressed by the equation E=mc2.

It’s most likely that the particles are tetraquarks, particles composed of four quarks tightly bound together, says physicist Tomasz Skwarnicki of Syracuse University in New York, who led the analysis. For decades, scientists thought quarks grouped up only into pairs or triplets, but recent research has unearthed tetraquarks (SN: 7/27/13, p. 9) and even pentaquarks (SN: 8/8/15, p. 8). A competing explanation, that the particles are molecule-like pairings made up of two quark partners each, has been ruled out, Skwarnicki says.

Even among tetraquarks, the particles are unusual because they are made up solely of heavy, exotic types of quarks. The lightest quarks, known as up and down quarks, make up protons and neutrons. Heavier quarks — like the charm and strange quarks that make up the new family — are not found in everyday materials.

Physics writer Emily Conover has a Ph.D. in physics from the University of Chicago. She is a two-time winner of the D.C. Science Writers’ Association Newsbrief award.

Use up and down arrow keys to explore.Use right arrow key to move into the list.Use left arrow key to move back to the parent list.Use tab key to enter the current list item.Use escape to exit the menu.Use the Shift key with the Tab key to tab back to the search input.
Logo

Looks like your ad blocker is on.

×

We rely on ads to keep creating quality content for you to enjoy for free.

Please support our site by disabling your ad blocker.

Continue without supporting us

Choose your Ad Blocker

  • Adblock Plus
  • Adblock
  • Adguard
  • Ad Remover
  • Brave
  • Ghostery
  • uBlock Origin
  • uBlock
  • UltraBlock
  • Other
  1. In the extension bar, click the AdBlock Plus icon
  2. Click the large blue toggle for this website
  3. Click refresh
  1. In the extension bar, click the AdBlock icon
  2. Under "Pause on this site" click "Always"
  1. In the extension bar, click on the Adguard icon
  2. Click on the large green toggle for this website
  1. In the extension bar, click on the Ad Remover icon
  2. Click "Disable on This Website"
  1. In the extension bar, click on the orange lion icon
  2. Click the toggle on the top right, shifting from "Up" to "Down"
  1. In the extension bar, click on the Ghostery icon
  2. Click the "Anti-Tracking" shield so it says "Off"
  3. Click the "Ad-Blocking" stop sign so it says "Off"
  4. Refresh the page
  1. In the extension bar, click on the uBlock Origin icon
  2. Click on the big, blue power button
  3. Refresh the page
  1. In the extension bar, click on the uBlock icon
  2. Click on the big, blue power button
  3. Refresh the page
  1. In the extension bar, click on the UltraBlock icon
  2. Check the "Disable UltraBlock" checkbox
  3. Marque la casilla de verificación "Desactivar UltraBlock"
  1. Please disable your Ad Blocker
  2. Disable any DNS blocking tools such as AdGuardDNS or NextDNS

If the prompt is still appearing, please disable any tools or services you are using that block internet ads (e.g. DNS Servers).