о как буксует физика идеи потеряв

за формулы все физики
запрятали обман
и пишут труд размером
в большой густой роман
за формулами виден
их нищенский карман...
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 Dark Matter from Exponential Growth
Torsten Bringmann ,
1,*
Paul Frederik Depta ,
2,†
Marco Hufnagel,
3,‡
Joshua T. Ruderman,
4,2,5,6,§
and Kai Schmidt-Hoberg
2,;
1
Department of Physics, University of Oslo, Box 1048, N-0316 Oslo, Norway
2
Deutsches Elektronen-Synchrotron DESY, Notkestra;e 85, D-22607 Hamburg, Germany
3
Service de Physique Th;eorique, Universit;e Libre de Bruxelles, Boulevard du Triomphe, CP225, B-1050 Brussels, Belgium
4
Center for Cosmology and Particle Physics, Department of Physics, New York University, New York, New York 10003, USA
5
Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA
6
School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel
(Received 25 June 2021; revised 20 August 2021; accepted 14 September 2021; published 3 November 2021)
We propose a novel mechanism for the production of dark matter (DM) from a thermal bath based on the
idea that DM particles;can transform heat bath particles;:;;;;;. For a small initial abundance of ;,
this leads to an exponential growth of the DMnumber density in close analogy to other familiar exponential

production in a generic way, opening new parameter space to explain the observed DM abundance, and we
discuss observational prospects for such scenarios.
DOI:10.1103/PhysRevLett.127.191802
Introduction.—While the identity and underlying proper-
ties of the dark matter (DM) in our Universe remain
mysterious, its energy density has been precisely inferred
by a series of satellite missions studying the cosmic
microwave background (CMB). Any theoretical descrip-
tion of DM must therefore include a DM production
mechanism that leads to the observed DM relic abundance
of;DMh
2
;0.12[1].
A particularly appealing framework for the genesis of
DM, minimizing the dependence on initial conditions, is its
creation out of a thermal bath. The most commonly adopted

from the primordial plasma of standard model (SM)
particles in the early Universe[2]. However, given the
increasingly strong constraints on this setup, a plethora of
alternate production scenarios with DM initially in thermal
equilibrium have recently been proposed, including“hid-

“Cannibal DM” [12,13], “Coscattering DM” [14–16],
“Zombie DM” [17], “Elder DM” [18], “Kinder DM”
[19], and “SIMP DM”[20–22]. Another possibility is that
DM never entered thermal equilibrium at all, in which case
it can be produced via a “leakage”out of a thermal bath,


suggested, less model building has been performed around

In this Letter, we propose a novel and generic DM
production scenario between these two polarities based on
the idea that a DM particle ;can“transform”a heat bath
particle;into another ;; cf. Fig. 1. For a small initial
abundancen;
, as shown below, this results in an expo-
nential growth of the DM abundance. To be in accord with
observations, the exponential growth is required to shut off
before the DM particle;is fully thermalized, so one can
also think of this mechanism as a“failed thermalization.”
Interestingly, the exponential growth of n; comes to an
end naturally in our framework, so that the observed DM
abundance is readily obtained.
A novel DMproduction mechanism.—Quantitatively, the
evolution of the DM number densityn; is governed by the
Boltzmann equation
FIG. 1. The transformation process leading to exponential
production of DM (;) from the heat bath (;).
Published by the American Physical Society under the terms of
the Creative Commons Attribution 4.0 Internationallicense.
Further distribution of this work must maintain attribution to
the author(s) and the published article’s title, journal citation,
and DOI. Funded by SCOAP
3
.
PHYSICAL REVIEW LETTERS127,191802 (2021)
Editors' Suggestion Featured in Physics
0031-9007=21=127(19)=191802(6) 191802-1 Published by the American Physical Society