1,712 research outputs found
The Effective Field Theory of Dark Matter Direct Detection
We extend and explore the general non-relativistic effective theory of dark
matter (DM) direct detection. We describe the basic non-relativistic building
blocks of operators and discuss their symmetry properties, writing down all
Galilean-invariant operators up to quadratic order in momentum transfer arising
from exchange of particles of spin 1 or less. Any DM particle theory can be
translated into the coefficients of an effective operator and any effective
operator can be simply related to most general description of the nuclear
response. We find several operators which lead to novel nuclear responses.
These responses differ significantly from the standard minimal WIMP cases in
their relative coupling strengths to various elements, changing how the results
from different experiments should be compared against each other. Response
functions are evaluated for common DM targets - F, Na, Ge, I, and Xe - using
standard shell model techniques. We point out that each of the nuclear
responses is familiar from past studies of semi-leptonic electroweak
interactions, and thus potentially testable in weak interaction studies. We
provide tables of the full set of required matrix elements at finite momentum
transfer for a range of common elements, making a careful and fully
model-independent analysis possible. Finally, we discuss embedding
non-relativistic effective theory operators into UV models of dark matter.Comment: 32+23 pages, 5 figures; v2: some typos corrected and definitions
clarified; v3: some factors of 4pi correcte
A Simple Explanation for DAMA with Moderate Channeling
We consider the possibility that the DAMA signal arises from channeled events
in simple models where the dark matter interaction with nuclei is suppressed at
small momenta. As with the standard WIMP, these models have two parameters (the
dark matter mass and the size of the cross-section), without the need to
introduce an additional energy threshold type of parameter. We find that they
can be consistent with channeling fractions as low as about ~ 15%, so long as
at least ~70% of the nuclear recoil energy for channeled events is deposited
electronically. Given that there are reasons not to expect very large
channeling fractions, these scenarios make the channeling explanation of DAMA
much more compelling.Comment: 6 pages, 2 figure
Non-relativistic effective theory of dark matter direct detection
Dark matter direct detection searches for signals coming from dark matter
scattering against nuclei at a very low recoil energy scale ~ 10 keV. In this
paper, a simple non-relativistic effective theory is constructed to describe
interactions between dark matter and nuclei without referring to any underlying
high energy models. It contains the minimal set of operators that will be
tested by direct detection. The effective theory approach highlights the set of
distinguishable recoil spectra that could arise from different theoretical
models. If dark matter is discovered in the near future in direct detection
experiments, a measurement of the shape of the recoil spectrum will provide
valuable information on the underlying dynamics. We bound the coefficients of
the operators in our non-relativistic effective theory by the null results of
current dark matter direct detection experiments. We also discuss the mapping
between the non-relativistic effective theory and field theory models or
operators, including aspects of the matching of quark and gluon operators to
nuclear form factors.Comment: 35 pages, 3 figures, Appendix C.3 revised, acknowledgments and
references adde
The Cosmology of Composite Inelastic Dark Matter
Composite dark matter is a natural setting for implementing inelastic dark
matter - the O(100 keV) mass splitting arises from spin-spin interactions of
constituent fermions. In models where the constituents are charged under an
axial U(1) gauge symmetry that also couples to the Standard Model quarks, dark
matter scatters inelastically off Standard Model nuclei and can explain the
DAMA/LIBRA annual modulation signal. This article describes the early Universe
cosmology of a minimal implementation of a composite inelastic dark matter
model where the dark matter is a meson composed of a light and a heavy quark.
The synthesis of the constituent quarks into dark mesons and baryons results in
several qualitatively different configurations of the resulting dark matter
hadrons depending on the relative mass scales in the system.Comment: 31 pages, 4 figures; references added, typos correcte
Household Decision Making and Savings Impacts: Further Evidence from a Commitment Savings Product in the Philippines
Puzzles of Dark Matter - More Light on Dark Atoms?
Positive results of dark matter searches in experiments DAMA/NaI and
DAMA/LIBRA confronted with results of other groups can imply nontrivial
particle physics solutions for cosmological dark matter. Stable particles with
charge -2, bound with primordial helium in O-helium "atoms" (OHe), represent a
specific nuclear-interacting form of dark matter. Slowed down in the
terrestrial matter, OHe is elusive for direct methods of underground Dark
matter detection using its nuclear recoil. However, low energy binding of OHe
with sodium nuclei can lead to annual variations of energy release from OHe
radiative capture in the interval of energy 2-4 keV in DAMA/NaI and DAMA/LIBRA
experiments. At nuclear parameters, reproducing DAMA results, the energy
release predicted for detectors with chemical content other than NaI differ in
the most cases from the one in DAMA detector. Moreover there is no bound
systems of OHe with light and heavy nuclei, so that there is no radiative
capture of OHe in detectors with xenon or helium content. Due to dipole Coulomb
barrier, transitions to more energetic levels of Na+OHe system with much higher
energy release are suppressed in the correspondence with the results of DAMA
experiments. The proposed explanation inevitably leads to prediction of
abundance of anomalous Na, corresponding to the signal, observed by DAMA.Comment: Contribution to Proceedings of XIII Bled Workshop "What Comes beyond
the Standard Model?
Searches for Long Lived Neutral Particles
An intriguing possibility for TeV scale physics is the existence of neutral
long lived particles (LOLIPs) that subsequently decay into SM states. Such
particles are many cases indistinguishable from missing transverse energy (MET)
at colliders. We propose new methods to search for these particles using
neutrino telescopes. We study their detection prospects, assuming production
either at the LHC or through dark matter (DM) annihilations in the Sun and the
Earth. We find that the sensitivity for LOLIPs produced at the LHC is limited
by luminosity and detection energy thresholds. On the other hand, in the case
of DM annihilation into LOLIPs, the sensitivity of neutrino telescopes is
promising and may extend beyond the reach of upcoming direct detection
experiments. In the context of low scale hidden sectors weakly coupled to the
SM, such indirect searches allow to probe couplings as small as 10^-15.Comment: 22 pages, 6 figure
The Tevatron at the Frontier of Dark Matter Direct Detection
Direct detection of dark matter (DM) requires an interaction of dark matter
particles with nucleons. The same interaction can lead to dark matter pair
production at a hadron collider, and with the addition of initial state
radiation this may lead to mono-jet signals. Mono-jet searches at the Tevatron
can thus place limits on DM direct detection rates. We study these bounds both
in the case where there is a contact interaction between DM and the standard
model and where there is a mediator kinematically accessible at the Tevatron.
We find that in many cases the Tevatron provides the current best limit,
particularly for light dark matter, below 5 GeV, and for spin dependent
interactions. Non-standard dark matter candidates are also constrained. The
introduction of a light mediator significantly weakens the collider bound. A
direct detection discovery that is in apparent conflict with mono-jet limits
will thus point to a new light state coupling the standard model to the dark
sector. Mono-jet searches with more luminosity and including the spectrum shape
in the analysis can improve the constraints on DM-nucleon scattering cross
section.Comment: 20 pages, 8 figures, final version in JHE
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