Featured Research

from universities, journals, and other organizations

Dilaton Could Affect Abundance Of Dark Matter Particles

Date:
October 2, 2007
Source:
BioMed Central
Summary:
The amount of dark matter left over from the early universe may be less than previously believed. The 'relic abundance' of stable dark matter particles such as the neutralino may be reduced as compared to standard cosmology theories due to the effects of the 'dilaton,' a particle with zero spin in the gravitational sector of strings.

The amount of dark matter left over from the early universe may be less than previously believed. New research shows that the "relic abundance" of stable dark matter particles such as the neutralino may be reduced as compared to standard cosmology theories due to the effects of the "dilaton", a particle with zero spin in the gravitational sector of strings.

Related Articles


Nikolaos Mavromatos of King's College London and colleagues in Athens and Texas obtained their result by studying a special "off-shell" time-dependent term (due to the dilaton) in the Boltzmann equation that describes the evolution of hot matter density as the Universe cooled down. "The formalism that this work used was developed in partial collaboration with John Ellis of CERN and Vasiliki Mitsou of IFIC, Valencia, and is a version of 'non-critical string theory'", said Mavromatos.

Dark matter is fundamentally different from normal, luminous matter and is invisible to modern telescopes, giving off no light or heat. It appears to interact with normal matter only through gravity. Most cosmologists believe dark matter, currently thought to make up 95% of all matter in the universe, plays a crucial role in how large structures such as galaxies emerged after the Big Bang.

All the matter and radiation in the universe is thought to have been created by the Big Bang. The radiation stopped interacting with the matter some 400,000 years later -- when the universe had cooled down enough for electrons and protons to form hydrogen atoms. The density of dark matter particles such as the neutralino (a dark matter candidate favoured by many of the current "supersymmetric" approaches to particle physics) was therefore "frozen" at this time -- the so-called relic abundance.

The researchers say that the neutralino relic abundance is reduced by as much as a factor of ten in their models due to dilaton effects, as compared to standard cosmology theories. In contrast, the relic abundance of "ordinary" matter, which makes up stars, planets and humans, is only slightly diluted. The new model also agrees with the established model of nucleosynthesis (the way in which light elements were created during the first few minutes of the universe).

The new result is important for both cosmology and particle physics, says Mavromatos. Indeed, such non-equilibrium string cosmology models are on an equal footing with the standard cosmological cold dark matter model (called Lambda-CDM). For particle physics, the findings are relevant for future supersymmetric searches in colliders such as the Large Hadron Collider, due to come on-line at CERN early next year. The supersymmetric theory, one of the facets of string theory, postulates that every particle has a massive "shadow" particle partner.

Article: Dilaton and off-shell (non-critical string) effects in Boltzmann equation for species abundances, A.B. Lahanas et al., PMC Physics A (in press)


Story Source:

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


Cite This Page:

BioMed Central. "Dilaton Could Affect Abundance Of Dark Matter Particles." ScienceDaily. ScienceDaily, 2 October 2007. <www.sciencedaily.com/releases/2007/10/071002084628.htm>.
BioMed Central. (2007, October 2). Dilaton Could Affect Abundance Of Dark Matter Particles. ScienceDaily. Retrieved October 24, 2014 from www.sciencedaily.com/releases/2007/10/071002084628.htm
BioMed Central. "Dilaton Could Affect Abundance Of Dark Matter Particles." ScienceDaily. www.sciencedaily.com/releases/2007/10/071002084628.htm (accessed October 24, 2014).

Share This



More Space & Time News

Friday, October 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

China Prepares Unmanned Mission To Lunar Orbit

China Prepares Unmanned Mission To Lunar Orbit

Newsy (Oct. 23, 2014) — The mission is China's next step toward automated sample-return missions and eventual manned missions to the moon. Video provided by Newsy
Powered by NewsLook.com
Russian Cosmonauts Kick Off Final Spacewalk of 2014

Russian Cosmonauts Kick Off Final Spacewalk of 2014

Reuters - US Online Video (Oct. 22, 2014) — Russian cosmonauts Maxim Suraev and Alexander Samokutyaev step outside the International Space Station to perform work on the exterior of the station's Russian module. Rough Cut (no reporter narration) Video provided by Reuters
Powered by NewsLook.com
Comet Siding Spring Grazes Mars' Atmosphere

Comet Siding Spring Grazes Mars' Atmosphere

Newsy (Oct. 19, 2014) — A comet from the farthest reaches of the solar system passed extremely close to Mars this weekend, giving astronomers a rare opportunity to study it. Video provided by Newsy
Powered by NewsLook.com
Latin America Launches Communications Satellite

Latin America Launches Communications Satellite

AFP (Oct. 17, 2014) — Argentina launches a home-built satellite, a first for Latin America. It will ride a French-made Ariane 5 rocket into orbit, and will provide cell phone, digital TV, Internet and data services to the lower half of South America. Duration: 00:41 Video provided by AFP
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:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

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