Related Experiment Video
Updated: Jul 4, 2026
07:46
Setting Limits on Supersymmetry Using Simplified Models
Published on: November 15, 2013
Low mass dimuons produced in relativistic nuclear collisions
Jörg Ruppert1, Charles Gale, Thorsten Renk
1Department of Physics, McGill University, 3600 University Street, Montreal, QC, H3A 2T8 Canada.
Physical Review Letters
|June 4, 2008
Summary
The NA60 experiment precisely measured muon pairs from indium-indium collisions. Results align with a dynamical model, indicating in-medium meson properties at high temperature and density.
Area of Science:
- Nuclear Physics
- Particle Physics
- High-Energy Physics
Background:
- Understanding particle production in heavy-ion collisions is crucial for probing matter under extreme conditions.
- Previous studies in lead-lead and lead-gold collisions provided foundational data on hadronic properties.
Purpose of the Study:
- To precisely measure low-mass muon pair production in indium-indium collisions at 158A GeV.
- To test the validity of a dynamical model using parameters derived from other collision systems.
- To investigate the in-medium properties of rho and omega mesons.
Main Methods:
- Utilizing the NA60 experiment to record muon pair production events.
- Employing a dynamical model fitted to hadronic transverse mass spectra and Hanbury Brown-Twiss correlations.
- Comparing experimental data with model predictions, incorporating finite temperature and density effects.
Main Results:
- The NA60 data for muon pair production are well-reproduced by the dynamical model.
- Measurements are consistent with in-medium modifications of rho and omega mesons.
- Vacuum decay of the rho meson post-freeze-out is essential for describing dimuons below 0.9 GeV/c(2).
Conclusions:
- The dynamical model successfully describes muon pair production in indium-indium collisions.
- The study provides evidence for modified meson properties in hot and dense nuclear matter.
- Accurate modeling requires accounting for rho meson decay after the system has expanded.
Related Concept Videos
03:37Subatomic Particles
Dalton was only partially correct about the particles that make up matter. All matter is composed of atoms, and atoms are composed of three smaller subatomic particles: protons, neutrons, and electrons. These three particles account for the mass and the charge of an atom.
03:18Nuclear Stability
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively charged protons together in the...
To hold positively charged protons together in the...
03:20Nuclear Transmutation
Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with another particle. The first manmade nucleus was produced in Ernest Rutherford’s laboratory in 1919 by a transmutation reaction, the bombardment of one type of nuclei with other nuclei or with neutrons. Rutherford bombarded nitrogen-14 atoms with high-speed α particles from a natural radioactive isotope of radium and observed protons being...
01:12Reduced Mass Coordinates: Isolated Two-body Problem
In classical mechanics, the two-body problem is one of the fundamental problems describing the motion of two interacting bodies under gravity or any other central force. When considering the motion of two bodies, one of the most important concepts is the reduced mass coordinates, a quantity that allows the two-body problem to be solved like a single-body problem. In these circumstances, it is assumed that a single body with reduced mass revolves around another body fixed in a position with an...
02:45Nuclear Fusion
The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass into large amounts of energy, a process called fusion. The principal source of energy in the sun is a net fusion reaction in which four hydrogen nuclei fuse and ultimately produce one helium nucleus and two positrons.
A helium nucleus has a mass that is 0.7% less than that of four hydrogen nuclei; this lost mass is converted into energy during the fusion. This reaction produces about...
A helium nucleus has a mass that is 0.7% less than that of four hydrogen nuclei; this lost mass is converted into energy during the fusion. This reaction produces about...
01:23Atomic Nuclei: Nuclear Relaxation Processes
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis. This...