Physics Letters B 790 (2019) 345–353
Contents lists available at ScienceDirect
Physics Letters B
www.elsevier.com/locate/physletb
Analysis of branon dark matter and extra-dimensional models with
AMS-02
Jose A.R. Cembranos
a,b
, Álvaro de la Cruz-Dombriz
c
, Peter K.S. Dunsby
c,d
,
Miguel Méndez-Isla
c,∗
a
Departamento de Física Teórica I, Universidad Complutense de Madrid, E-28040 Madrid, Spain
b
UPARCOS, Universidad Complutense de Madrid, E-28040 Madrid, Spain
c
Cosmology and Gravity Group, Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, Cape Town, South Africa
d
South African Astronomical Observatory, Observatory 7925, Cape Town, South Africa
a r t i c l e i n f o a b s t r a c t
Article history:
Received
5 November 2018
Received
in revised form 7 December 2018
Accepted
8 January 2019
Available
online 25 January 2019
Editor:
M. Trodden
In the context of brane-world extra-dimensional theories, we compute the positron production from
branon dark matter annihilations and compare with the AMS-02 data. Three different scenarios have been
considered; the first two assume that either pulsars or dark matter may explain separately the whole
positron fraction as measured by AMS-02, whereas the third one assumes that a suitable combination
of these two contributions is needed. For all of them, exclusion diagrams for the brane mass and the
tension of the brane, were obtained. Our analysis has been performed for a minimal, a medium and a
maximum diffusion model in one extra dimension for both pseudo-Isothermal and Navarro–Frenk–White
dark matter halos. Combined with previous cosmological analyses and experimental data in colliders,
constraints here enable us to set further bounds on the parameter space of branons. In particular, in
the case when pulsars fit the whole AMS-02 data, we have excluded mass-tension regions for masses
and tensions smaller than 60.75 TeV and 8.56 TeV respectively. With regard to the scenario in which
AMS-02 data are explained by a combination of dark matter and pulsars, masses and tensions smaller
than 27.32 TeV and 3.85 TeV respectively turn out to be excluded. Finally, in the scenario with no
pulsar contribution, a branon with a mass 38.1 ± 0.2TeV and a tension 4.99 ± 0.04 TeV can fit well
the experimental data.
© 2019 Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP
3
.
1. Introduction
The positron fraction when the electron/positron (e
+
/e
−
) the-
oretical
background is only explained in terms of spallation of
cosmic rays (secondary products) presents an excess for energies
up to 10 GeV as measured by some detectors, such as AMS-02
[1–3], PAMELA [4,5]HEAT [6]or Fermi [7]. This phenomenon has
opened a wide discussion about the origin and the reliability of
models of cosmic-ray propagation. In order to explain such an ex-
cess,
it is necessary to introduce additional sources by injecting
e
+
/e
−
pairs. The main astrophysical sources [8,9]to interpret such
a result are supernovae remnants (SNRs) [10], the secondary pro-
duction
of positrons in the interstellar medium (ISM) generated by
spallation of cosmic rays [11] and nearby pulsars [12]. Hence, tak-
ing
into account the contributions from averaged distant sources,
*
Corresponding author.
E-mail
address: mndmig001@myuct.ac.za (M. Méndez-Isla).
fluxes from both local supernovae (Green Catalog [13]) and pul-
sars
from the ATNF database [14](such as Geminga, J1741-2054
or Monogem), the measurements of AMS-02 can be well fitted [8].
Also, further explanations, such as annihilating dark matter (DM)
in the Milky Way halo, have also been considered in the literature
very recently [15–18]. Thus DM sources could either partially or
completely explain the aforementioned excess [19–22]. Although
some studies fit this excess with either astrophysical sources or
DM separately, the big space of parameters accounting for both
astrophysical sources and DM contributions, enables us to describe
the positron excess with a combination of them (cf. [23–25]for re-
cent
attempts) bearing in mind that no source model can produce
more e
+
/e
−
than those observed by experimental data.
As
is widely known, there is an outstanding variety of astro-
physical
and cosmological phenomena which require us to resort
to DM to obtain an accurate explanation. Among these observa-
tions,
the most remarkable pieces of evidence are, among oth-
ers,
the presence of DM in the Coma [26,27] and Bullet Clus-
https://doi.org/10.1016/j.physletb.2019.01.011
0370-2693/
© 2019 Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP
3
.