True neutral particles

True neutral particles
True neutral particles
Classification	See #Specifications
Group	Neutral particle
Participates in interactions	Gravitational (general)
Antiparticle	Yourself
Number of types	8 (non-composite)
In honor of whom or what is named	Truth and neutral particle
Quantum numbers
Electric charge	0
Color charge	0
Baryon number	0
Lepton number	0
B − L	0
Spin	1/2 Крат
Magnetic moment	0
Isotopic spin	0
Weirdness	0
Charm	0
The beauty	0
Truth	0
Hypercharge	0

Truly neutral particles are elementary particles or systems of elementary particles, which transfer into themselves upon charge conjugation , that is, they are antiparticles for themselves. Sometimes they also say that they do not have antiparticles.

In order for a particle to be called truly neutral, it is not enough that the particle is electrically neutral . Many neutral particles, such as the neutron , the hyperons Σ ⁰ and Ξ ⁰ , the mesons D ⁰ and B ⁰ , as well as neutrinos , have antiparticles different from themselves. True neutral particles are completely identical to their antiparticles, so all their quantum numbers , which change sign upon charge conjugation, must be zero. Thus, true neutral particles have zero values of electric charge , magnetic moment , baryon and lepton numbers , isotopic spin , strangeness , charm , charm , truth , color .

Content

Non-composite true neutral particles

Of the non-composite particles, the truly neutral particles are the photon , the Z-boson , the neutral Higgs boson , and two colorless gluons $g_{3}$ ${\ displaystyle g_ {3}}$ and $g_{8}$ ${\ displaystyle g_ {8}}$ . In addition, there are many hypothetical truly neutral particles: graviton , axion , etc. All these particles are bosons . All known fermions have any difference from their antiparticles, but in 1937 Ettore Majorana indicated the possibility of the existence of a truly neutral fermion. This hypothetical particle is called the Majorana particle . Hypothetical particles of neutralino in supersymmetric models are fermoions of Majorana.

Compound Truly Neutral Particles

True neutral particles can be not only individual elementary particles, but also their systems, including systems from an even number of fermions. For example, positronium — a system of positrons and electrons — is a truly neutral particle, since in charge conjugation the positron is replaced by an electron, and the electron is replaced by a positron, thus again forming positronium.

According to modern concepts, truly neutral mesons π ⁰ , φ ⁰ , η ^0, and others are also constituent particles — systems of quark and antiquark of the same flavor (the so-called quarkonia ).

Charge parity

True neutral particles have a characteristic of them only - charge parity , which shows how its state vector changes when replacing particles with antiparticles.

Characteristics

Particle	Symbol	GeV / c²	Portable interaction	Interactions, in which participates	Spin	Life time , c	Decay Example (> 5%)	Electric charge, e
Photon	γ	0 (<10 ⁻²² eV / c ² ) ^[2] ^[3]	Electromagnetic interaction	Electromagnetic interaction, gravitational interaction	one	Stable		0 (<10 ⁻³⁵ e ) ^[4] ^[5]
Z boson	Z	91.1876 ± 0.0021 ^[6]	Weak interaction	Weak interaction, gravitational interaction	one	3⋅10 ⁻²⁵	l + l (lepton + corresponding antilepton) ^[6]	0
Gluons $g_{3}$ ${\ displaystyle g_ {3}}$ and $g_{8}$ ${\ displaystyle g_ {8}}$	$g_{3}$ ${\ displaystyle g_ {3}}$ and $g_{8}$ ${\ displaystyle g_ {8}}$	0 (theoretical value) ^[7] < 0.0002 eV / c2 (experimental restriction) ^[8]	Strong interaction	Strong interaction, gravitational interaction	one	Not found in the free state		0 ^[7]
Higgs boson	H 0	125.26 ± 0.21 ^[9]	Higgs field (not recognized fundamental interaction )	Higgs field, weak interaction, gravitational interaction	0	1.56⋅10 ^-22 ^{[Note 1]} (prediction of the Standard Model )	Two photons , W and Z bosons ^[11]	0
Graviton	G	0 (theory) <1.1 × 10 ⁻²⁹ eV / c ² ^[12] (experimental upper limit)	Gravity	Gravitational interaction	2	Hypothetical particle		0
Axion	A 0	From 10 ⁻¹⁸ to 1 MeV / c ²		Electromagnetic interaction	0	Hypothetical particle	A 0 → γ + γ	0
Majorana fermion					½	Hypothetical particle		0
Neutraline	N͂ ⁰	> 300 ^[13]		Weak interaction	½ ^[14]	Hypothetical particle		0

Comments

↑ In the Standard Model , the decay width of the Higgs boson with a mass of 126 GeV / s2 is predicted to be 4.21⋅10 ^-3 GeV . ^[10] Average lifetime $\tau =\hbar /\Gamma$ ${\ displaystyle \ tau = \ hbar / \ Gamma}$ .

Notes

↑ The amazing world inside the atomic nucleus. Questions after the lecture , LPI, September 11, 2007
К Kerr's black holes helped physicists weigh photons (2012)
↑ Pani Paolo, Cardoso Vitor, Gualtieri Leonardo, Berti Emanuele, Ishibashi Akihiro. Black-Hole Bombs and Photon-Mass Bounds (Eng.) // Physical Review Letters . - 2012. - Vol. 109 , iss. 13 - P. 131102 (5 p.) . - DOI : 10.1103 / PhysRevLett.109.131102 .
↑ Particle Data Group (2008)
↑ Kobychev, VV; Popov, SB Constraints on the photon charge from observations of extragalactic sources (Eng.) // Astronomy Letters : journal. - 2005. - Vol. 31 . - P. 147-151 . - DOI : 10.1134 / 1.1883345 . (eng.)
Altschul, B. Bound on the Photon of the Phase Coverage of Extragalactic Radiation (Eng.) // Physical Review Letters : journal. - 2007. - Vol. 98 - P. 261801 . (eng.)
↑ ¹ ² J. Beringer et al . (Particle Data Group), Phys. Rev. D86, 010001 (2012). Gauge bosons, Z boson. Available at pdglive.lbl.gov Archived July 12, 2012. (eng.)
↑ ¹ ² W.-M. Yao et al. Review of Particle Physics (Unsub.) // Journal of Physics G . - 2006. - V. 33 . - S. 1 . - DOI : 10.1088 / 0954-3899 / 33/1/001 . - . - arXiv : astro-ph / 0601168 .
↑ F. Yndurain. Limits on the mass of the gluon ( Neopr .) // Physics Letters B . - 1995. - V. 345 , № 4 . - p . 524 . - DOI : 10.1016 / 0370-2693 (94) 01677-5 . - .
↑ News of the Large Hadron Collider: ATLAS and CMS again "weighed" the Higgs boson (Neopr.) . old.elementy.ru . The date of circulation is July 30, 2017.
↑ LHC Higgs Cross Section Working Group; Dittmaier; Mariotti; Passarino; Tanaka; Alekhin; Alwall; Bagnaschi; Banfi Handbook of LHC Higgs Cross Sections: 2. Differential Distributions (English) // CERN Report 2 (Tables A.1 - A.20): journal. - 2012. - Vol. 1201 . - P. 3084 . - . - arXiv : 1201.3084 .
↑ The Higgs Boson // LN Smirnova. ATLAS DETECTOR OF A BIG ADRONNE COLLIDER. Department of General Nuclear Physics, Faculty of Physics, MSU
↑ Goldhaber AS, Nieto MM Mass of the graviton // Physical Review D. - 1974. - Vol. 9. - P. 1119-1121. - ISSN 0556-2821 . - DOI : 10.1103 / PhysRevD.9.1119 .
↑ Supersymmetry in the light of LHC data: what to do next? Review of experimental data
↑ Introduction Fundamental Particles Properties of Supersymmetric Particles

Literature

Truly Neutral Particles - an article from the Physical Encyclopedia

Links

Ung Chan Tsan. What is a truly neutral particle? (Eng.) // International Journal of Modern Physics E. - 2004. - Vol. 13 , no. 2 - P. 425-437 . - DOI : 10.1142 / S0218301304002272 .

[meanlife-11] In the Standard Model , the decay width of the Higgs boson with a mass of 126 GeV / s2 is predicted to be 4.21⋅10 ^-3 GeV . ^[10] Average lifetime $\tau =\hbar /\Gamma$ ${\ displaystyle \ tau = \ hbar / \ Gamma}$ .

[elementyGrav-1] The amazing world inside the atomic nucleus. Questions after the lecture , LPI, September 11, 2007

[2] К Kerr's black holes helped physicists weigh photons (2012)

[3] Pani Paolo, Cardoso Vitor, Gualtieri Leonardo, Berti Emanuele, Ishibashi Akihiro. Black-Hole Bombs and Photon-Mass Bounds (Eng.) // Physical Review Letters . - 2012. - Vol. 109 , iss. 13 - P. 131102 (5 p.) . - DOI : 10.1103 / PhysRevLett.109.131102 .

[DPG-4] Particle Data Group (2008)

[chargeless-5] Kobychev, VV; Popov, SB Constraints on the photon charge from observations of extragalactic sources (Eng.) // Astronomy Letters : journal. - 2005. - Vol. 31 . - P. 147-151 . - DOI : 10.1134 / 1.1883345 . (eng.)
Altschul, B. Bound on the Photon of the Phase Coverage of Extragalactic Radiation (Eng.) // Physical Review Letters : journal. - 2007. - Vol. 98 - P. 261801 . (eng.)

[pdg_Z-6] ¹ ² J. Beringer et al . (Particle Data Group), Phys. Rev. D86, 010001 (2012). Gauge bosons, Z boson. Available at pdglive.lbl.gov Archived July 12, 2012. (eng.)

[pdg-7] ¹ ² W.-M. Yao et al. Review of Particle Physics (Unsub.) // Journal of Physics G . - 2006. - V. 33 . - S. 1 . - DOI : 10.1088 / 0954-3899 / 33/1/001 . - . - arXiv : astro-ph / 0601168 .

[8] F. Yndurain. Limits on the mass of the gluon ( Neopr .) // Physics Letters B . - 1995. - V. 345 , № 4 . - p . 524 . - DOI : 10.1016 / 0370-2693 (94) 01677-5 . - .

[9] News of the Large Hadron Collider: ATLAS and CMS again "weighed" the Higgs boson (Neopr.) . old.elementy.ru . The date of circulation is July 30, 2017.

[LHCcrosssections-10] LHC Higgs Cross Section Working Group; Dittmaier; Mariotti; Passarino; Tanaka; Alekhin; Alwall; Bagnaschi; Banfi Handbook of LHC Higgs Cross Sections: 2. Differential Distributions (English) // CERN Report 2 (Tables A.1 - A.20): journal. - 2012. - Vol. 1201 . - P. 3084 . - . - arXiv : 1201.3084 .

[12] The Higgs Boson // LN Smirnova. ATLAS DETECTOR OF A BIG ADRONNE COLLIDER. Department of General Nuclear Physics, Faculty of Physics, MSU

[13] Goldhaber AS, Nieto MM Mass of the graviton // Physical Review D. - 1974. - Vol. 9. - P. 1119-1121. - ISSN 0556-2821 . - DOI : 10.1103 / PhysRevD.9.1119 .

[elementyExp-14] Supersymmetry in the light of LHC data: what to do next? Review of experimental data

[elp01-15] Introduction Fundamental Particles Properties of Supersymmetric Particles