Featured Research

from universities, journals, and other organizations

Exotic particle: Exotic bound states comprising more than three quarks confirmed

Date:
June 6, 2014
Source:
Forschungszentrum Juelich
Summary:
For decades, physicists have searched in vain for exotic bound states comprising more than three quarks. Experiments have now shown that, in fact, such complex particles do exist in nature. The measurements confirm first results from 2011 for the existence of an exotic dibaryon made up of six quarks.

For a long time, physicists were only able to reliably verify two different classes of hadrons: baryons and mesons. Experiments performed at Jülich’s accelerator COSY have now shown that, in fact, another class of exotic particles made up of six quarks exists.
Credit: Forschungszentrum Jülich/SeitenPlan (CC BY 4.0, http://creativecommons.org/licenses/by/4.0/)

For decades, physicists have searched in vain for exotic bound states comprising more than three quarks. Experiments performed at Jülich's accelerator COSY have now shown that, in fact, such complex particles do exist in nature. This discovery by the WASA-at-COSY collaboration has been published in the journal Physical Review Letters. The measurements confirm results from 2011, when the more than 120 scientists from eight countries discovered for the first time strong indications for the existence of an exotic dibaryon made up of six quarks.

For a long time, physicists were only able to reliably verify two different classes of hadrons: volatile mesons comprising one quark and one antiquark and baryons consisting of three quarks. Protons and neutrons, which make up atomic nuclei, are examples of the latter. In recent years, however, there has been growing evidence for the existence of additional types of hadrons, for example, hybrids, glueballs, and multiquarks. In 1964, the physicist Freeman Dyson was the first to predict such more complex states. But any reliable verification proved impossible for many years because almost no measurements could be reproduced.

Only recently, other research groups -- independently of each other -- found strong indications for short-lived, exotic particles comprising four quarks, so called "tetraquarks." The new bound state, which has now been verified at COSY, means that yet another class of exotic particles has been identified. "The new resonance that we observed confirms that quarks really do exist in six-packs. This discovery could open the door to new physical phenomena," says group spokesman Prof. Heinz Clement from the University of Tübingen.

The structure that was first discovered in 2011 is extremely short-lived and could only be detected via its decay products. The transient intermediate state -- technical term: resonance -- exists for a mere hundred-sextillionth (10 to the power of -23) of a second before it decays. This time span is so short that, for example, light can travel just a distance equivalent to the diameter of a small atomic nucleus.

Whether all six quarks form a single compact entity or rather a "hadronic molecule" has yet to be clarified. The latter would be composed of several nuclear building blocks -- for example of excited protons and neutrons bound to each other -- yet much more strongly than inside an atomic nucleus.

"The measurements that we performed at COSY in 2011 were already very precise. But because the experiments could not be repeated at any other accelerator worldwide, we had to come up with another experiment to verify the results," explains Prof. Hans Ströher, director at the Nuclear Physics Institute (IKP-2) in Jülich.

In order to gain further unequivocal evidence of the exotic resonance named d*(2380), the scientists scanned the relevant energy range in an elastic scattering experiment. They bombarded a proton target with polarized, heavy hydrogen nuclei known as deuterons. The exotic bound state formed during the collision influenced the angle with which the particles moved away from each other after the collision, thus allowing it to be identified .

"The findings are part of a bigger picture. If this particle exists, then theoretically a whole range of other exotic states can be expected," says director at Jülich's IKP-1 Prof. James Ritman. The nuclear physicist is in charge of Jülich's contribution to the PANDA detector at the international accelerator complex FAIR in Darmstadt, where such exotic structures will be explored in more detail.


Story Source:

The above story is based on materials provided by Forschungszentrum Juelich. Note: Materials may be edited for content and length.


Journal Reference:

  1. P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, F. S. Bergmann, M. Berłowski, H. Bhatt, M. Büscher, H. Calén, I. Ciepał, H. Clement, D. Coderre, E. Czerwiński, K. Demmich, E. Doroshkevich, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. Föhl, K. Fransson, F. Goldenbaum, P. Goslawski, A. Goswami, K. Grigoryev, C.-O. Gullström, F. Hauenstein, L. Heijkenskjöld, V. Hejny, M. Hodana, B. Höistad, N. Hüsken, A. Jany, B. R. Jany, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, F. A. Khan, A. Khoukaz, D. A. Kirillov, S. Kistryn, H. Kleines, B. Kłos, M. Krapp, W. Krzemień, P. Kulessa, A. Kupść, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Mariański, M. Mikirtychiants, H.-P. Morsch, P. Moskal, H. Ohm, I. Ozerianska, E. Perez del Rio, N. M. Piskunov, P. Podkopał, D. Prasuhn, A. Pricking, D. Pszczel, K. Pysz, A. Pyszniak, C. F. Redmer, J. Ritman, A. Roy, Z. Rudy, S. Sawant, S. Schadmand, T. Sefzick, V. Serdyuk, V. Serdyuk, R. Siudak, T. Skorodko, M. Skurzok, J. Smyrski, V. Sopov, R. Stassen, J. Stepaniak, E. Stephan, G. Sterzenbach, H. Stockhorst, H. Ströher, A. Szczurek, A. Täschner, A. Trzciński, R. Varma, G. J. Wagner, M. Wolke, A. Wrońska, P. Wüstner, P. Wurm, A. Yamamoto, L. Yurev, J. Zabierowski, M. J. Zieliński, A. Zink, J. Złomańczuk, P. Żuprański, M. Żurek, R. L. Workman, W. J. Briscoe, I. I. Strakovsky. Evidence for a New Resonance from Polarized Neutron-Proton Scattering. Physical Review Letters, 2014; 112 (20) DOI: 10.1103/PhysRevLett.112.202301

Cite This Page:

Forschungszentrum Juelich. "Exotic particle: Exotic bound states comprising more than three quarks confirmed." ScienceDaily. ScienceDaily, 6 June 2014. <www.sciencedaily.com/releases/2014/06/140606102043.htm>.
Forschungszentrum Juelich. (2014, June 6). Exotic particle: Exotic bound states comprising more than three quarks confirmed. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2014/06/140606102043.htm
Forschungszentrum Juelich. "Exotic particle: Exotic bound states comprising more than three quarks confirmed." ScienceDaily. www.sciencedaily.com/releases/2014/06/140606102043.htm (accessed July 31, 2014).

Share This




More Matter & Energy News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Britain Testing Driverless Cars on Roadways

Britain Testing Driverless Cars on Roadways

AP (July 30, 2014) — British officials said on Wednesday that driverless cars will be tested on roads in as many as three cities in a trial program set to begin in January. Officials said the tests will last up to three years. (July 30) Video provided by AP
Powered by NewsLook.com
Amid Drought, UCLA Sees Only Water

Amid Drought, UCLA Sees Only Water

AP (July 30, 2014) — A ruptured 93-year-old water main left the UCLA campus awash in 8 million gallons of water in the middle of California's worst drought in decades. (July 30) Video provided by AP
Powered by NewsLook.com
Smartphone Powered Paper Plane Debuts at Airshow

Smartphone Powered Paper Plane Debuts at Airshow

AP (July 30, 2014) — Smartphone powered paper airplane that was popular on crowdfunding website KickStarter makes its debut at Wisconsin airshow (July 30) Video provided by AP
Powered by NewsLook.com
U.K. To Allow Driverless Cars On Public Roads

U.K. To Allow Driverless Cars On Public Roads

Newsy (July 30, 2014) — Driverless cars could soon become a staple on U.K. city streets, as they're set to be introduced to a few cities in 2015. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



    Save/Print:
    Share:  

    Free Subscriptions


    Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

    Get Social & Mobile


    Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

    Have Feedback?


    Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
    Mobile iPhone Android Web
    Follow Facebook Twitter Google+
    Subscribe RSS Feeds Email Newsletters
    Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins