105 research outputs found
Direct Detection of Dark Matter particles with Long Range Interaction
We study the effect of a long-range DM-nuclei interaction occurring via the
exchange of a light mediator. We consider the main direct detection
experiments: DAMA, CoGeNT, CRESST, CDMS and XENON100. We find that a long-range
force is a viable mechanism, which can provide full agreement between the
various experiments, especially for masses of the mediator in the 10-30 MeV
range and a light DM with a mass around 10 GeV. The relevant bounds on the
light mediator mass and scattering cross section are then derived.Comment: 3 pages, 1 figure; To appear in the Proceedings of the 47th
Rencontres de Moriond on Cosmolog
Constraints on Dark Matter annihilations from reionization and heating of the intergalactic gas
Dark Matter annihilations after recombination and during the epoch of
structure formation deposit energy in the primordial intergalactic medium,
producing reionization and heating. We investigate the constraints that are
imposed by the observed optical depth of the Universe and the measured
temperature of the intergalactic gas. We find that the bounds are significant,
and have the power to rule out large portions of the `DM mass/cross section'
parameter space. The optical depth bound is generally stronger and does not
depend significantly on the history of structure formation. The temperature
bound can be competitive in some cases for small masses or the hadronic
annihilation channels (and is affected somewhat by the details of structure
formation). We find in particular that DM particles with a large annihilation
cross section into leptons and a few TeV mass, such as those needed to explain
the PAMELA and FERMI+HESS cosmic ray excesses in terms of Dark Matter, are
ruled out as they produce too many free electrons. We also find that low mass
particles (<~ 10 GeV) tend to heat too much the gas and are therefore
disfavored.Comment: 22 pages, 5 figures; v2: minor comments added, matches version
published on JCA
Bounds on Dark Matter annihilations from 21 cm data
The observation of an absorption feature in the 21 cm spectrum at redshift
implies bounds on Dark Matter annihilations for a broad range of
masses, given that significant heating of the intergalactic medium would have
erased such feature. The resulting bounds on the DM annihilation cross sections
are comparable to the strongest ones from all other observables.Comment: 8 pages. v2: improved treatment of energy depositio
New Directions in Direct Dark Matter Searches
I present the status of direct dark matter detection with specific attention
to the experimental results and their phenomenological interpretation in terms
of dark matter interactions. In particular I review a new and more general
approach to study signals in this field based on non-relativistic operators
which parametrize more efficiently the dark matter-nucleus interactions in
terms of a very limited number of relevant degrees of freedom. Then I list the
major experimental results, pointing out the main uncertainties that affect the
theoretical interpretation of the data. Finally, since the underlying theory
that describes both the dark matter and the standard model fields is unknown, I
address the uncertainties coming from the nature of the interaction. In
particular, the phenomenology of a class of models in which the interaction
between dark matter particles and target nuclei is of a long-range type is
discussed.Comment: 28 pages, 5 figures; Invited review for special issue on "Direct Dark
Matter Search (DMS)" to appear in Advances in High Energy Physic
Helioseismology with long range dark matter-baryon interactions
Assuming the existence of a primordial asymmetry in the dark sector, we study
how DM-baryon long-range interactions, induced by the kinetic mixing of a new
gauge boson and the photon, affects the evolution of the Sun and in turn
the sound speed profile obtained from helioseismology. Thanks to the explicit
dependence on the exchanged momenta in the differential cross section
(Rutherford-like scattering), we find that dark matter particles with a mass of
, kinetic mixing parameter of the order of and a
mediator with a mass smaller than a few MeV improve the agreement between the
best solar model and the helioseismic data without being excluded by direct
detection experiments. In particular, the \LUX\ detector will soon be able to
either constrain or confirm our best fit solar model in the presence of a dark
sector with long-range interactions that reconcile helioseismology with thermal
neutrino results.Comment: v2: new section on the importance of the self-interaction added,
discussion on its magnitude added, some clarifications and some references
added, few typos corrected, results slightly modified; matches version
published on ApJ ; article with 12 pages and 4 figure
You can hide but you have to run: direct detection with vector mediators
We study direct detection in simplified models of Dark Matter (DM) in which
interactions with Standard Model (SM) fermions are mediated by a heavy vector
boson. We consider fully general, gauge-invariant couplings between the SM, the
mediator and both scalar and fermion DM. We account for the evolution of the
couplings between the energy scale of the mediator mass and the nuclear energy
scale. This running arises from virtual effects of SM particles and its
inclusion is not optional. We compare bounds on the mediator mass from direct
detection experiments with and without accounting for the running. In some
cases the inclusion of these effects changes the bounds by several orders of
magnitude, as a consequence of operator mixing which generates new interactions
at low energy. We also highlight the importance of these effects when
translating LHC limits on the mediator mass into bounds on the direct detection
cross section. For an axial-vector mediator, the running can alter the derived
bounds on the spin-dependent DM-nucleon cross section by a factor of two or
more. Finally, we provide tools to facilitate the inclusion of these effects in
future studies: general approximate expressions for the low energy couplings
and a public code runDM to evolve the couplings between arbitrary energy
scales.Comment: 26 pages + appendices, 9 + 2 figures. The runDM code is available at
https://github.com/bradkav/runDM/. v2: references added, version published in
JHE
Millicharge or Decay: A Critical Take on Minimal Dark Matter
Minimal Dark Matter (MDM) is a theoretical framework highly appreciated for
its minimality and yet its predictivity. Of the two only viable candidates
singled out in the original analysis, the scalar eptaplet has been found to
decay too quickly to be around today, while the fermionic quintuplet is now
being probed by indirect Dark Matter (DM) searches. It is therefore timely to
critically review the MDM paradigm, possibly pointing out generalizations of
this framework. We propose and explore two distinct directions. One is to
abandon the assumption of DM electric neutrality in favor of absolutely stable,
millicharged DM candidates which are part of multiplets with
integer isospin. Another possibility is to lower the cutoff of the model, which
was originally fixed at the Planck scale, to allow for DM decays. We find new
viable MDM candidates and study their phenomenology in detail.Comment: 24 pages + appendices, 5 figures. v2: references added; v3: added
discussion on millicharged MDM eptaplet; some clarifications and references
added; conclusions unchanged; matches version to be published in JCA
Faint Light from Dark Matter: Classifying and Constraining Dark Matter-Photon Effective Operators
Even if Dark Matter (DM) is neutral under electromagnetism, it can still
interact with the Standard Model (SM) via photon exchange from
higher-dimensional operators. Here we classify the general effective operators
coupling DM to photons, distinguishing between Dirac/Majorana fermion and
complex/real scalar DM. We provide model-independent constraints on these
operators from direct and indirect detection. We also constrain various
DM-lepton operators, which induce DM-photon interactions via RG running or
which typically arise in sensible UV-completions. This provides a simple way to
quickly assess constraints on any DM model that interacts mainly via photon
exchange or couples to SM leptons.Comment: 32 pages + appendices, 9 + 1 figures, 2 + 1 tables. v2: some
clarifications and references added; conclusions unchanged; version published
in JHE
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