Fifth Force| Fifth Force |
In General > s.a. Hyperphoton.
* Idea: In principle, any hypothetical
force in addition to the four interactions of the standard model of particle physics;
In practice, there are a few types of fifth force that have been considered more than
others, such as a hypercharge-dependent one studied in the late 1980s in connection
with a reanalysis of the Eötvös experiment by Fischbach et al, and various
dilaton-field-dependent forces motivated by low-energy limits of Kaluza-Klein theories
and string theory, or by scalar-tensor theories of gravity more generally; The latter
need not violate the weak equivalence principle.
* Hypercharge-dependent: A type of force
that could be coupled to a combination B cosθ + S
sinθ of baryon number and strangeness (hypercharge seems antiquated)
which, for bulk matter, gives rise to a dependence on the material, e.g., because
near the center of the periodic table nuclear binding is tightest, and B/mass
highest; If one interprets the fifth force as a component of gravity, then the fifth
force violates the weak equivalence principle; The potential is parametrized by a
Yukawa-type form given by, if Y1 and
Y2 are the hypercharges of the two particles
involved,
U(r) = f 2 Y1 Y 2 exp{−r/λ}/ r .
Phenomenology and Tests
> s.a. Eötvös Experiment; tests of general
relativity and of newtonian gravitation.
* History: Some indications of the possible
existence of a fifth force had been coming from geophysical methods of testing newtonian
gravitation, but the question received a lot of attention with the reanalysis of the
Eötvös data by Fischbach et al (1986), following anomalous results in neutral
K-meson experiments at Fermilab, which could be explained by a long-range force
coupled to Y; It stimulated many new gravitational gradiometer, free fall,
Cavendish or Eötvös-type experiments; 2016 and 2019, Claimed detection of
X17 boson by Krasznahorkay et al, mass 16.7 MeV.
* Bounds: 2005, At the AU-scale, planet motion
studies constrain the strength of this force to a 10−12
– 10−13 level; 2018, from the
MICROSCOPE space mission.
@ Tests and bounds:
Iorio PSS(07)gq/05 [AU-scale, from planet motion];
Farrar & Rosen PRL(07)
+ pw(07)may
[galaxy cluster-scale, from Bullet Cluster];
Ferreira et al PRD(17)-a1612 [no fifth force in a scale-invariant universe];
news pw(18)apr [from the MICROSCOPE space mission];
Sun et al PRD(19)-a1910 [from planet perihelion precession];
Fischbach et al a2012 [composition-dependent effects].
@ Possible detections:
Krasznahorkay et al PRL(16)-a1504,
comment Quanta(16)jun [signal from 8Be transition];
Feng et al PRL(16)-a1604 [protophobic X boson interpretation];
Krasznahorkay et al a1910
+ news cnn(19)nov [new evidence for X17 from 4He transition].
> Related topics:
see dark matter;
Galileon Field; Unparticles.
References
@ Books: Franklin 93;
Franklin & Fischbach 16.
@ General: Fischbach et al PRL(86),
PRL(86),
AP(88);
De Rújula PLB(86);
Eckhardt PRL(86);
Nussinov PRL(86);
Thieberger PRL(87);
Nieto et al PRD(88);
Burgess & Cloutier PRD(88) [from binary precession];
Fischbach & Talmadge Nat(92)mar;
Romaides et al PRD(97) [tower experiment].
@ News: Stubbs Nat(89)mar;
Waldrop Sci(89)nov;
NS(90)jul21, p18.
@ From 5th dimension:
Wesson et al PLB(99);
Dahia et al MPLA(03).
@ Related topics: Krauss PT(08)oct [re spoof].
> Online resources:
see Wikipedia page.
main page
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send feedback and suggestions to bombelli at olemiss.edu – modified 13 dec 2020