ANTITAU
Definition and characteristics
The term "antitau lepton" likely refers to the antiparticle counterpart of the tau lepton, which is one of the three types of heavy leptons in the Standard Model of particle physics. The tau lepton, denoted as τ, has an electric charge of -1e and a mass significantly larger than that of the electron and muon.
The antitau lepton, denoted as τ⁻ (tau minus), is the antimatter counterpart of the tau lepton. Like all antiparticles, the antitau lepton has opposite electric charge compared to its corresponding particle. Therefore, the antitau lepton carries a positive electric charge of +1e.
Key characteristics of the antitau lepton include:
Charge: The antitau lepton has a positive electric charge of +1e, in contrast to the negative charge of the tau lepton.
Mass: The antitau lepton has a mass of approximately 1777 MeV/c² (megaelectronvolts per speed of light squared), making it significantly heavier than both the electron and the muon.
Spin: Like all leptons, both the tau lepton and its antiparticle have a spin of 1/2 ħ (reduced Planck's constant), indicating their intrinsic angular momentum.
Lifetime: The tau lepton and its antiparticle are unstable and decay into lighter particles. The lifetime of the tau lepton is very short, on the order of 2.9 x 10-13 seconds, and the antitau lepton would have a similar lifetime.
Weak Interaction: Tau leptons, like other leptons, interact via the weak force, which is responsible for processes such as beta decay. The weak force is one of the fundamental forces in the Standard Model.
Production and Detection: Antitau leptons can be produced in high-energy particle collisions, such as those occurring in particle accelerators. They can be detected through their decay products, which typically include lighter leptons, neutrinos, and other particles, depending on the decay channel.
Combinations with antitau leptons
The tau lepton is predicted to form exotic atoms like other charged subatomic particles. One of such, consists of an antitau and an electron: τ+ e−, called tauonium.
Another one is an onium atom τ+ τ− called ditauonium or true tauonium, which is challenging to detect due to the difficulty to form it from two (opposite-sign) short-lived tau leptons.[1] Its experimental detection would be an interesting test of quantum electrodynamics. [2]
Creation of antitau lepton
Antitau leptons can be created through various processes in high-energy particle interactions. These processes typically occur in particle accelerators or cosmic-ray interactions. Here are some key mechanisms for antitau lepton production:
Pair Production in Electron-Positron Collisions:
In high-energy electron-positron collisions, where electrons and positrons (antielectrons) annihilate each other, the released energy can be used to create particle-antiparticle pairs. This includes the creation of tau and antitau lepton pairs. The energy required for tau-antitau production is higher compared to processes involving lighter particles due to the tau lepton's larger mass.
Related Papers : See Tau Pair Production
Electron-positron annihilation :
An electron and positron can annihilate and via the Z°-boson can a tau antitau pair be created.
Related Papers : See Annihilation of electrons
Weak Decays of Heavy Particles:
Heavy particles, such as certain mesons and baryons, can undergo weak decays that produce tau-antitau lepton pairs. These decays are mediated by the weak force, one of the fundamental forces in particle physics. Examples include the decay of certain types of charmed mesons or baryons that result in tau and antitau lepton production.
Tau Lepton Production in Hadron Collisions:
Tau leptons, including their antiparticles, can be produced in high-energy hadron collisions, where protons or other hadrons collide. The collision energy must be sufficient to create tau-antitau lepton pairs directly or through the decay of other particles produced in the collision.
Top Quark Decays:
The top quark, the heaviest known quark, can decay into a W boson and a bottom quark. The W boson can then decay into a tau lepton and its corresponding neutrino, leading to the production of tau and antitau leptons. This process occurs in top quark-antiquark pair production and subsequent decays
Related Papers : see Top Quark Decay
Tau Lepton Production in Neutrino Interactions:
Neutrinos, which interact weakly with other particles, can participate in interactions that produce tau leptons. In some cases, antitau leptons are also produced in such interactions, typically in neutrino-nucleon scattering processes.
Figure 261 - Electron-positron annihilation creating antitau lepton
Figure 264 - Leading-order Feynman diagram for t ¯ t decay
Figure 263 - Diagrams of the main production mechanisms of tau leptons in electron–proton collisions: a) tau pair production via photon–photon collisions and b) single W boson production
Figure 262 - emission process of a tau-antitau pair by a proton of incoming momentum p,
mediated by a photon or a Z boson
Figure 265 - Schematics of the production and decay topology of a tau-lepton produced in CHORUS by a tau-neutrino possibly generated in the oscillation of the muon neutrinos of the CERN WANF beam.
E. Annihilation of the antitau lepton
The annihilation of a tau anti-tau lepton can lead to the creation of W or Z bosons.
Related Papers (See Annihilation of the Tau Lepton)
F. Fusion of antitau leptons
See annihilation of the tau lepton
Related Papers (See Fusion of the Tau Lepton)
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References
[1] d'Enterria, David; Perez-Ramos, Redamy; Shao, Hua-Sheng (2022). "Ditauonium spectroscopy". European Physical Journal C. 82 (10): 923. arXiv:2204.07269. doi:10.1140/epjc/s10052-022-10831-x. S2CID 248218441
[2] d'Enterria, David; Shao, Hua-Sheng (2023). "Prospects for ditauonium discovery at colliders". Physics Letters B. 842: 137960. arXiv:2302.07365. doi:10.1016/j.physletb.2023.137960.