An experiment conducted by an international research team has confirmed the existence of Higgs boson, which is widely believed to grant mass to substances in the universe, establishing the standard theory of the elementary particle.
The team, comprising researchers from the University of Tokyo, the High-Energy Accelerator Research Organization and overseas research institutes, will announce the confirmation in the Oct. 7 issue of European science journal “Physics Letters B.”
Dr. Peter Higgs, who proposed the theory of Higgs boson in 1964, is widely viewed as the most likely candidate for the Nobel Prize in Physics, especially with the confirmation of the elementary particle’s existence.
In July last year, the Switzerland-based European Organization for Nuclear Research (CERN) – which has the Large Hadron Collider (LHC) used in the experiment – announced that researchers were more than 99.9999 percent certain they had found a new particle that they believed to be Higgs boson.
Still, more experiments were necessary to confirm the existence of the elementary particle.
By examining the process of Higgs boson decaying and changing into other elementary particles, the researchers confirmed that the mass of the particle is 125.5 giga electron volts, approximately 134 times that of a proton. [wkipedia says 125.3±0.6 GeV ] …
It also confirmed that the particle’s spin is zero, which is consistent with the theory of Higgs boson.
Why measure particle mass as an amount of energy?
By mass–energy equivalence, the electronvolt is also a unit of mass. It is common in particle physics, where mass and energy are often interchanged, to express mass in units of eV/c2, where c is the speed of light in vacuum (from E = mc2). It is common to simply express mass in terms of “eV” as a unit of mass, effectively using a system of natural units with c set to 1.
The Mass equivalent of 1 eV is 1.783×10−36 kg.
For example, an electron and a positron, each with a mass of 0.511 MeV/c2, can annihilate to yield 1.022 MeV of energy. The proton has a mass of 0.938 GeV/c2. In general, the masses of all hadrons are of the order of1 GeV/c2, which makes the GeV(gigaelectronvolt) a convenient unit of mass for particle physics:
1 GeV/c2 = 1.783×10−27 kgThe atomic mass unit, 1 gram divided by Avogadro’s number, is almost the mass of a hydrogen atom, which is mostly the mass of the proton. To convert to megaelectronvolts, use the formula [3:
How do different particles compare in terms of energy?
From small to large:
µeV = micro electron volts
meV = milli electron volts
eV = electron volts
MeV = mega electron volts
GeV = giga electron volts
TeV = tera electron volts
PeV = peta electron volts
EeV = exa electron volts
- 5.25×1032 eV: total energy released from a 20 kt nuclear fission device
- ~624 EeV (6.24×1020 eV): energy consumed by a single 100-watt light bulb in one second (100 W = 100 J/s = ~6.24×1020 eV/s)
- 300 EeV (3×1020 eV = ~50 J):[7 the so-called Oh-My-God particle (the most energetic cosmic ray particle ever observed)
- 1 PeV: one petaelectronvolt, the amount of energy measured in each of two different cosmic neutrino candidates detected by the IceCube neutrino telescope in Antarctica
- 14 TeV: the designed proton collision energy at the Large Hadron Collider (which has operated at half of this energy since 30 March 2010)
- 1 TeV: a trillion electronvolts, or1.602×10−7 J, about the kinetic energy of a flying mosquito
- 125.3±0.6 GeV: the energy emitted by the decay of the Higgs Boson, as measured by two separate detectors at the LHC to a certainty of 5 sigma
- 210 MeV: the average energy released in fission of one Pu-239 atom
- 200 MeV: the average energy released in nuclear fission of one U-235 atom
- 17.6 MeV: the average energy released in the fusion of deuterium and tritium to form He-4; this is 0.41 PJ per kilogram of product produced
- 1 MeV (1.602×10−13 J): about twice the rest energy of an electron
- 13.6 eV: the energy required to ionize atomic hydrogen; molecular bond energies are on the order of 1 eV to 10 eV per bond
- 1.6 eV to 3.4 eV: the photon energy of visible light
- 25 meV: the thermal energy kBT at room temperature; one air molecule has an average kinetic energy 38 meV
- 230 µeV: the thermal energy kBT of the cosmic microwave background