Weakly Interacting Massive Particles Properties Research Articles

Effects of threshold energy on reconstructions of properties of low-mass WIMPs in direct dark matter detection experiments

In this paper, we revisit our model-independent methods developed for reconstructing properties of Weakly Interacting Massive Particles (WIMPs) by using measured recoil energies from direct Dark Matter detection experiments directly and take into account more realistically non-negligible threshold energy. All expressions for reconstructing the mass and the (ratios between the) spin-independent and the spin-dependent WIMP–nucleon couplings have been modified. We focus on low-mass ([Formula: see text] GeV) WIMPs and present the numerical results obtained by Monte Carlo simulations. Constraints caused by non-negligible threshold energy and technical treatments for improving reconstruction results will also be discussed.

The semi-Hooperon: Gamma-ray and anti-proton excesses in the Galactic Center

A puzzling excess in gamma-rays at GeV energies has been observed in the center of our galaxy using Fermi-LAT data. Its origin is still unknown, but it is well fitted by Weakly Interacting Massive Particles (WIMPs) annihilations into quarks with a cross section around 10−26 cm3s−1 with masses of 20–50 GeV, scenario which is promptly revisited. An excess favoring similar WIMP properties has also been seen in anti-protons with AMS-02 data potentially coming from the Galactic Center as well. In this work, we explore the possibility of fitting these excesses in terms of semi-annihilating dark matter, dubbed as semi-Hooperon, with the process WIMPWIMP→WIMPX being responsible for the gamma-ray excess, where X=h,Z. An interesting feature of semi-annihilations is the change in the relic density prediction compared to the standard case, and the possibility to alleviate stringent limits stemming from direct detection searches. Moreover, we discuss which models might give rise to a successful semi-Hooperon setup in the context of Z3,Z4 and extra “dark” gauge symmetries.

Dark matter in the Reticulum II dSph: a radio search

We present a deep radio search in the Reticulum II dwarf spheroidal (dSph) galaxy performed with the Australia Telescope Compact Array. Observations were conducted at 16 cm wavelength, with an rms sensitivity of 0.01 mJy/beam, and with the goal of searching for synchrotron emission induced by annihilation or decay of weakly interacting massive particles (WIMPs). Data were complemented with observations on large angular scales taken with the KAT-7 telescope. We find no evidence for a diffuse emission from the dSph and we derive competitive bounds on the WIMP properties. In addition, we detect more than 200 new background radio sources. Among them, we show there are two compelling candidates for being the radio counterpart of the possible γ-ray emission reported by other groups using Fermi-LAT data.

WIMP physics with ensembles of direct-detection experiments

The search for weakly-interacting massive particle (WIMP) dark matter is multi-pronged. Ulti- mately, the WIMP-dark-matter picture will only be confirmed if different classes of experiments see consistent signals and infer the same WIMP properties. In this work, we review the ideas, meth- ods, and status of direct-detection searches. We focus in particular on extracting WIMP physics (WIMP interactions and phase-space distribution) from direct-detection data in the early discov- ery days when multiple experiments see of order dozens to hundreds of events. To demonstrate the essential complementarity of different direct-detection experiments in this context, we create mock data intended to represent the data from the near-future Generation 2 experiments. We consider both conventional supersymmetry-inspired benchmark points (with spin-independent and -dependent elastic cross sections just below current limits), as well as benchmark points for other classes of models (inelastic and effective-operator paradigms). We also investigate the effect on parameter estimation of loosening or dropping the assumptions about the local WIMP phase-space distribution. We arrive at two main conclusions. Firstly, teasing out WIMP physics with experi- ments depends critically on having a wide set of detector target materials, spanning a large range of target nuclear masses and spin-dependent sensitivity. It is also highly desirable to obtain data from low-threshold experiments. Secondly, a general reconstruction of the local WIMP velocity distribu- tion, which will only be achieved if there are multiple experiments using different target materials, is critical to obtaining a robust and unbiased estimate of the WIMP mass.

A review on the discovery reach of Dark Matter directional detection

Directional detection of galactic Dark Matter offers a unique opportunity to identify Weakly Interacting Massive Particle (WIMP) events as such. Depending on the unknown WIMP-nucleon cross section, directional detection may be used to : exclude Dark Matter, discover galactic Dark Matter with a high significance or constrain WIMP and halo properties. We review the discovery reach of Dark Matter directional detection.

Galactic substructure and dark-matter annihilation in the Milky Way halo

We study the effects of substructure on the rate of dark-matter annihilation in the Galactic halo. We use an analytic model for substructure that can extend numerical simulation results to scales too small to be resolved by the simulations. We first calibrate the analytic model to numerical simulations, and then determine the annihilation boost factor, for standard weakly interacting massive particle (WIMP) models as well as those with Sommerfeld (or other) enhancements, as a function of galactocentric radius in the Milky Way. We provide an estimate of the dependence of the gamma-ray intensity of WIMP annihilation as a function of angular distance from the Galactic center. This methodology, coupled with future numerical simulation results can be a powerful tool that can be used to constrain WIMP properties using Fermi all-sky data.

Reconstructing WIMP properties in direct detection experiments including galactic dark matter distribution uncertainties

We present a new method for determining Weakly Interacting Massive Particle(WIMP) properties in future tonne scale direct detection experiments which accounts for uncertainties in the Milky Way (MW) smooth dark matter distribution. Using synthetic data on the kinematics of MW halo stars matching present samples from the Sloan Digital Sky Survey, complemented by local escape velocity constraints, we demonstrate that the local dark matter density can be constrained to ∼ 20% accuracy. For low mass WIMPs, we find that a factor of two error in the assumed local dark matter density leads to a severely biased reconstruction of the WIMP spin-independent cross section that is incorrect at the 15σ level. We show that this bias may be overcome by marginalizing over parameters that describe the MW potential, and use this formalism to project the accuracy attainable on WIMP properties in future 1 ton Xenon detectors. Our method can be readily applied to different detector technologies and extended to more detailed MW halo models.

Neutrino flavor ratios as diagnostic of solar WIMP annihilation

We consider the neutrino (and antineutrino) flavors arriving at the Earth for neutrinos produced in the annihilation of weakly interacting massive particles (WIMPs) in the sun's core. Solar-matter effects on the flavor propagation of the resulting ≥ GeV neutrinos are studied analytically within a density-matrix formalism. Matter effects, including mass-state level crossings, influence the flavor fluxes considerably. The exposition herein is somewhat pedagogical, in that it starts with adiabatic evolution of single flavors from the sun's center, with θ 13 set to zero, and progresses to fully realistic processing of the flavor ratios expected in WIMP decay, from the sun's core to the Earth. In the fully realistic calculation, nonadiabatic level crossing is included, as are possible nonzero values for θ 13 and the CP-violating phase δ. Because of resonance enhancement in matter, nonzero values of θ 13 even smaller than a degree can noticeably affect flavor propagation. Both normal and inverted neutrino-mass hierarchies are considered. Our main conclusion is that measuring flavor ratios (in addition to energy spectra) of ≥ GeV solar neutrinos can provide discrimination between WIMP models. In particular, we demonstrate the flavor differences at the Earth for neutrinos from the two main classes of WIMP final states, namely W + W ― and 95% bb + 5% τ + τ ― . Conversely, if WIMP properties were to be learned from production in future accelerators, then the flavor ratios of ≥ GeV solar neutrinos might be useful for inferring θ 13 and the mass hierarchy. From the full calculations, we find (and prove) some general features: a flavor-democratic flux produced at the sun's core arrives at the Earth still flavor democratic; for maximal θ 32 but arbitrary θ 21 and θ 13 , the replacement δ → π ― δ leaves the ν e flavor spectra unaltered but interchanges ν μ and ν τ spectra at the Earth; and, only for neutrinos in the inverted hierarchy and antineutrinos in the normal hierarchy is the dependence on the mixing phase δ not suppressed to order δm 2 21 /δm 2 32 .

Reconstructing WIMP properties with neutrino detectors

If the dark matter of the Universe is constituted by weakly interacting massive particles (WIMP), they would accumulate in the core of astrophysical objects as the Sun and annihilate into particles of the Standard Model. High-energy neutrinos would be produced in the annihilations, both directly and via the subsequent decay of leptons, quarks and bosons. While Čerenkov neutrino detectors/telescopes can only count the number of neutrinos above some threshold energy, we study how, by exploiting their energy resolution, large magnetized iron calorimeter and, possibly, liquid argon and totally active scintillator detectors, planned for future long baseline neutrino experiments, have the capability of reconstructing the neutrino spectrum and might provide information on the dark matter properties. In particular, for a given value of the WIMP mass, we show that a future iron calorimeter could break the degeneracy between the WIMP-proton cross section and the annihilation branching ratios, present for Čerenkov detectors, and constrain their values with good accuracy.

Connecting LHC, ILC, and quintessence

If the cold dark matter consists of weakly interacting massive particles (WIMPs), anticipated measurements of the WIMP properties at the Large Hadron Collider (LHC) and the International Linear Collider (ILC) will provide an unprecedented experimental probe of cosmology at temperatures of order 1 GeV. It is worth emphasizing that the expected outcome of these tests may or may not be consistent with the picture of standard cosmology. For example, in kination-dominated quintessence models of dark energy, the dark matter relic abundance can be significantly enhanced compared to that obtained from freeze out in a radiation-dominated universe. Collider measurements then will simultaneously probe both dark matter and dark energy. In this article, we investigate the precision to which the LHC and ILC can determine the dark matter and dark energy parameters under those circumstances. We use an illustrative set of four benchmark points in minimal supergravity in analogy with the four LCC benchmark points. The precision achievable together at the LHC and ILC is sufficient to discover kination-dominated quintessence, under the assumption that the WIMPs are the only dark matter component. The LHC and ILC can thus play important roles as alternative probes of both dark matter and dark energy.

Oscillations in solar models with weakly interacting massive particles

view Abstract Citations (12) References (20) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Oscillations in Solar Models with Weakly Interacting Massive Particles Gilliland, Ronald L. ; Dappen, Werner Abstract Solar models containing concentrations as low as 10-11 by number of weakly interacting massive particles (WIMPs), accreted from a galactic background population, are consistent with the observed flux of high-energy solar neutrinos. The structural changes produced in the solar core have also been shown to produce changes in the oscillation frequencies of g-modes and p-modes of low angular degree and high radial order. In this paper the authors examine the predictions for solar oscillations over a large range of possible WIMP properties. Publication: The Astrophysical Journal Pub Date: January 1988 DOI: 10.1086/165970 Bibcode: 1988ApJ...324.1153G Keywords: Particle Interactions; Solar Neutrinos; Solar Oscillations; Stellar Models; Weak Interactions (Field Theory); Particle Flux Density; Stellar Cores; Stellar Interiors; Vibration Mode; Solar Physics; ELEMENTARY PARTICLES; NEUTRINOS; SUN: INTERIOR; SUN: OSCILLATIONS full text sources ADS |

Cosmological constraints on the properties of weakly interacting massive particles

Considerations of the age and density of, as well as the evolution of structure in, the universe lead to constraints on the masses and lifetimes of weakly interacting massive particles (WIMPs). The requirement that the observed large-scale structure of the universe be permitted to develop, leads to much more restrictive bounds on the properties of WIMPs than those which follow from considerations of the age and density of the universe alone.