CP
Violation |

**In General** > s.a. atomic
physics; early-universe cosmology;
matter [antimatter]; neutrino
mixing; particle statistics.

* __Idea__: One of
several possible explanations for the matter-antimatter asymmetry (baryon
asymmetry) observed in the universe.

* __Theory__: Both
strong and weak interactions can violate CP (charge-parity) symmetry; The
effect can be described in terms of mixing in the CKM matrix (three angles
*α*, *β* and *γ* which form a non-degenerate CKM
unitarity triangle–the amount of violation is proportional to the area),
but could also be due to other physics; The standard model "predicts" a
value of sin(2*β*) between 0.66 and 0.84; Violations are likely to
be connected to baryon asymmetry, and maybe neutrino oscillations.

* __CKM matrix and
unitarity__: The entries *V*_{ij}
of the CKM matrix, where *i* = *u*, *c*, *t*,
and *j* = *d*, *s*, *b*, are the
amplitudes for the corresponding flavor-changing processes, and must be
unitary; The "unitarity triangle" is the expression one obtains when one
writes explicitly one of the unitarity conditions, *V*_{ub}
*V*_{ud}* + *V*_{cb}
*V*_{cd}* + *V*_{tb}
*V*_{td}* = 0 (so this
vanishing of the sum of three complex numbers is one of six such triangles
one can get from *V*_{ij},
but it is the one that contains the two most significant phases).

* __Idea, experiment__:
Can't measure all three CKM angles in the same experiment (BaBar and Belle
measure *α* and *β* – although *α* will require
much more data –, but need *B*_{s}s
to measure *γ*; Weak effects are esier to compare with theory.

* __In 2+1 dimensions__:
P and T are violated by particles with fractional statistics.

> __Online resources__:
see Wikipedia page.

**History, Status**

* __1957__: L Landau
argues that, although P can be violated, CP should not be; A Pais & M
Gell-Mann suggest that the K^{0} and K^{0}-bar
mesons are linear combinations of parity eigenstates K_{1}
(–1, long-lived, decays into 3*π*) and K_{2}
(+1, short-lived, decays into 2*π*); K_{1}
found by L Lederman et al.

* __1964__: Unexpected, first indirect evidence found by
Fitch & Cronin (CCFT) in K_{1} meson
decay into 2*π* [@ news pn(99)mar].

* __1998__: Indications
found by CDF in B meson decay.

* __1999__: Direct
evidence in K meson decay at Fermilab, *ε*'/*ε* = (28 ± 4)
× 10^{–4}, and CERN, (18.5 ± 7) × 10^{–4}.

* __2000__: RHIC now
online, will search for violations due to strong interaction, as opposed
to weak interactions; Results from B meson decay give sin(2*β*) =
0.45 ± 0.44 ± 0.45 (KEK) and 0.45 ± 0.44 ± 0.45 (BaBar at SLAC).

* __2001__:
Measurements from B meson decays give sin(2*β*) = 0.59 ± 0.14
(BaBar at SLAC) and 0.99 ± 0.14 (Belle at KEK); Aleph and CDF give
intermediate values; Strong interaction effects not yet seen.

* __2001__: Direct
violation – Differences between decays B mesons and their antiparticle
equivalents at BaBar.

* __2006__: The amount
of CP violation observed so far is insufficient to account for matter
domination (there may be more in quark, neutrino, or Higgs physics).

* __2012__:
Unexpectedly large violation seen in charmed meson decay.

* __2017__: CP violation seen in heavy baryon decays.

**References** > s.a. CPT
[including T-reversal]; modified QED; parity
[violation]; theta sectors.

@ __Reviews, news__: Adair SA(88)feb;
news PT(88)oct;
Harrison pw(03)jul;
news pw(06)apr;
Ibrahim & Nath RMP(08);
Kobayashi IJMPA(09);
Maskawa IJMPA(09);
Frère CRP(12)-a1201
[rev].

@ __Books__: Jarlskog 89;
Wolfenstein ed-90; Castelo
Branco et al 99
[r PT(00)aug];
Bigi & Sanda 09; Sozzi 12.

@ __General articles__: Fitch RMP(81);
Cronin RMP(81);
Rosner AJP(96)aug
[demo]; Rosner & Slezak AJP(01)jan
[classical analog]; Sozzi & Mannelli RNC(03)
[measurements]; Smit JHEP(04)hp
[and standard model effective action]; Gershon pw(07)apr
[unitarity triangle]; Ashtekar SHPMP-a1307-conf
[new perspective].

@ __Lepton sector__: Branco & Rebelo NJP(05)
[and neutrino mass]; Dita PRD(06)-a1101;
Farzan & Smirnov JHEP(07);
Pascoli et al PRD(07)
[and leptogenesis]; Winter PLB(09)
[neutrino propagation]; Branco et al RMP(12)
[rev]; Fogli et al PRD(12)-a1205
[neutrino masses, mixings and phases]; > s.a. neutrino
mixing.

@ __Spontaneous violation__: Dorey et al JPA(01)
[and supersymmetry]; Frampton IJMPA(02);
Balaji et al PLB(04)
[dynamical, early universe].

@ __ B-meson decays__: Green & McMahon CP(01);
Peruzzi
RNC(04);
Gronau
IJMPA(07).

@

@

@

**Related Topics** > s.a. Charge
Conjugation; electromagnetism [dipole
moments]; matter [mirror matter]; realism;
uncertainty relations.

@ __Strong CP problem__: Fort & Gambini ht/97
[in
loop formulation]; Dine hp/00-ln;
Hsu
& Sannino PLB(05);
Mitra
hp/05-conf
[no
problem]; Takahashi PTP(09)-a0804
[anthropic
solution]; Peccei AIP(10)-a1005
[history, and spontaneously-broken
chiral symmetry]; Swain a1005
[and
the existence of black holes]; Lattanzi & Mercuri PRD(10)-a1006
[solution via the
Peccei-Quinn
mechanism]; Acharya et al JHEP(10)
[M-theory solution]; Hook PRL(15)-a1411
[anomalous solutions].

@ __Other__: Home & Majumdar FP(99)qp
[and
Bohmian insert]; Huggett PhSc(00)jun
[*P* violation]; Bertlmann et al PLA(01)qp
[and
Bell inequalities];
Caliceti et al PLA(05)mp/04
[with
CPT symmetry]; Brauner et al PRL(12)-a1110
[temperature dependence of CP violation effects in the Standard Model].

main page –
abbreviations – journals
– comments – other
sites – acknowledgements

send feedback and suggestions to bombelli at olemiss.edu – modified 8 feb
2017