ρ meson

Rho meson (ρ + , ρ 0 , ρ - )
classification
Boson Hadron Meson
properties
electric charge	neutral or ± 1  e (0 or ± 1.602 10 −19  C )
Resting energy	775.26 (25)  MeV
Spin parity	1 -
Isospin	1 (z component + 1.0, -1)
Decay width	149.1 (8)  MeV
Quark composition	Up - Anti-Down, Up - Anti-Up or Down - Anti-Down, Down - Anti-Up

ρ mesons ( rho mesons ) are mesons with the same quark content as pions , but with spin one. You can therefore as angular momentum - suggestions the corresponding pions are considered and vector mesons.

description

Just like the pions form the ρ mesons an isotopic spin - triplet . This means that there are three different states are the ρ mesons: neutral ρ ⁰ , which is a superposition of states u u and d d represents

${\displaystyle |\rho ^{0}\rangle ={\frac {1}{\sqrt {2}}}\left(|d{\bar {d}}\rangle -|u{\bar {u}}\rangle \right)}$ ,

as well as the charged ρ ⁺

${\displaystyle |\rho ^{+}\rangle =|u{\bar {d}}\rangle }$

and ρ ^-

${\displaystyle |\rho ^{-}\rangle =|{\bar {u}}d\rangle }$.

Almost 100% of the ρ mesons decay into two pions under the strong force . As a result, they have a very short lifetime of around 4.5 · 10 ⁻²⁴ seconds or a very large decay range .

ρ-mesons could be detected in experiments for the first time in 1961.

particularities

ρ mesons are the lightest particles that decay under the strong interaction. This makes them particularly interesting from a theoretical point of view in current research, as the dynamics of the strong interaction can be studied using their example. In the last few years (as of 2011), for example, scattering processes of two pions have been simulated as part of grid QCD calculations . From this the mass and decay width of the resonance could be extracted.

See also

• List of mesons

Individual evidence

1. ↑ The information on the particle properties (info box) are, unless otherwise stated, taken from: J. Beringer et al. ( Particle Data Group ): 2013 Review of Particle Physics. In: Physical Review D . Vol. 86, 2012, 010001 and 2013 partial update for the 2014 edition. Particle Data Group, accessed May 22, 2018 . 
2. ↑ N. Nakamura et al . (2010): Particle listings - ρ (PDF file; 191 kB)
3. ^ AR Erwin, R. March, WD Walker and E. West: Evidence for a π-π Resonance in the I = 1, J = 1 State . In: Phys. Rev. Lett. No. 6 , 1961, pp. 628-630 , doi : 10.1103 / PhysRevLett.6.628 .
4. ^ DL Stonehill and HL Kraybill: Pion-Pion Interactions in π + -p collisions . In: Rev. Mod. Phys. No. 34 , 1962, pp. 503-507 , doi : 10.1103 / RevModPhys.34.503 .
5. ^ X. Feng, K. Jansen and D. Renner: Resonance parameters of the rho-meson from Lattice-QCD . In: Phys. Rev. D . No. 83 , 2011, p. 094505 , doi : 10.1103 / PhysRevD.83.094505 .