LUX Data Research Articles

Dipolar dark matter in light of the 3.5 keV x-ray line, neutrino mass, and LUX data

A simple extension of the standard model (SM) providing transient magnetic moments to right-handed neutrinos is presented. In this model, the decay of the next-to-lightest right-handed heavy neutrino to the lightest one and a photon (${N}_{2}\ensuremath{\rightarrow}{N}_{1}+\ensuremath{\gamma}$) can explain the $\ensuremath{\sim}3.5\text{ }\text{ }\mathrm{keV}$ x-ray line signal observed by the XMM-Newton X-ray observatory. Beside the SM particles and heavy right-handed Majorana neutrinos, the model contains a singly charged scalar (${H}^{\ifmmode\pm\else\textpm\fi{}}$) and an extra Higgs doublet ($\mathrm{\ensuremath{\Sigma}}$). Within this minimal set of extra fields the sub-eV masses of left-handed neutrinos are also explained. Moreover, we show that the spin-independent dark matter--nucleon cross section is compatible with the latest LUX data.

Direct Detection Phenomenology in Models Where the Products of Dark Matter Annihilation Interact with Nuclei.

We investigate the direct detection phenomenology of a class of dark matter (DM) models in which DM does not directly interact with nuclei, but rather, the products of its annihilation do. When these annihilation products are very light compared to the DM mass, the scattering in direct detection experiments is controlled by relativistic kinematics. This results in a distinctive recoil spectrum, a nonstandard and/or even absent annual modulation, and the ability to probe DM masses as low as a ∼10 MeV. We use current LUX data to show that experimental sensitivity to thermal relic annihilation cross sections has already been reached in a class of models. Moreover, the compatibility of dark matter direct detection experiments can be compared directly in Emin space without making assumptions about DM astrophysics, mass, or scattering form factors. Lastly, when DM has direct couplings to nuclei, the limit from annihilation to relativistic particles in the Sun can be stronger than that of conventional nonrelativistic direct detection by more than 3 orders of magnitude for masses in a 2-7 GeV window.

Constraining dark matter in the LRTH model with latest LHC, XENON100 and LUX data

In the left–right twin Higgs (LRTH) model, the neutral is a candidate for weakly interacting massive particle dark matter (DM). If its mass is lighter than half of the standard model-like Higgs boson h, the new invisible decay will become open. In this paper, we examine the status of a light DM () under current experimental constraints including the latest LHC Higgs data, the XENON100 and LUX limit on the DM scattering off the nucleon. The following observations have been obtained: (i) the current ATLAS (CMS) measurements of can exclude the invisible Higgs branching ratio larger than 34% (48%) at level; (ii) the Global fits to the latest LHC and Tevatron Higgs data provide a stronger constraint: (30%) at () level, which could be tested in the LHC experiments; (iii) for the spin-independent scattering cross section off the nucleon, the recent XENON100 (LUX) data can exclude the invisible decay rate larger than 50% (25%); and (iv) the results of direct DM searches with LUX can give strong constraint on the viable parameter space of in this LRTH model.

ResurrectingL-type sneutrino dark matter in light of neutrino masses and LUX data

In the minimal supersymmetric standard model (MSSM) the lightest superpartner of the left-handed neutrinos is ruled out of being a candidate of dark matter because of its large elastic cross-section with the nucleus mediated via Z-boson. We resurrect it by extending the MSSM with two triplets with opposite hypercharge. The addition of the triplets not only play a role in generating small Majorana masses for the left-handed active neutrinos but also make the lightest sneutrino a viable candidate for dark matter. We then discuss the relevant parameter space in details which can give rise to the right amount of (thermal) relic abundance as well as satisfy the current direct detection constraints from Xenon100 and LUX. We find that sneutrino dark matter with mass 370-550 GeV can give rise to right thermal relic abundance while co-annihilating with the bino-like neutralino.

A light SUSY dark matter after CDMS-II, LUX and LHC Higgs data

In SUSY, a light dark matter is usually accompanied by light scalars to achieve the correct relic density, which opens new decay channels of the SM like Higgs boson. Under current experimental constraints including the latest LHC Higgs data and the dark matter relic density, we examine the status of a light neutralino dark matter in the framework of NMSSM and confront it with the direct detection results of CoGeNT, CDMS-II and LUX. We have the following observations: (i) A dark matter as light as 8 GeV is still allowed and its scattering cross section off the nucleon can be large enough to explain the CoGeNT/CDMS-II favored region; (ii) The LUX data can exclude a sizable part of the allowed parameter space, but still leaves a light dark matter viable; (iii) The SM-like Higgs boson can decay into the light dark matter pair with an invisible branching ratio reaching 30% under the current LHC Higgs data, which may be tested at the 14 TeV LHC experiment.

An analysis of LUX data in the S2-only mode

An analysis of LUX data in the S2-only mode

Up-shot of inelastic down-scattering at CDMS-Si

We study dark matter that inelastically scatters and de-excites in direct detection experiments, as an interpretation of the CDMS-Si events in light of the recent LUX data. The constraints from LUX and XENON10 require the mass-splitting between the DM excited and de-excited states to be $|\delta| \gtrsim 50$ keV. At the same time, the CDMS-Si data itself do not allow for a consistent DM interpretation for mass splittings larger than $|\delta| \sim $200 keV. We find that a low threshold analysis will be needed to rule out this interpretation of the CDMS-Si events. In a simple model with a kinetically mixed dark photon, we show that the CDMS-Si rate and the thermal relic abundance can both be accommodated.

Update on light WIMP limits: LUX, lite and light

We reexamine the current direct dark matter data including the recent CDMSlite and LUX data, assuming that the dark matter consists of light WIMPs, with mass close to 10 GeV/c2 with spin-independent and isospin-conserving or isospin-violating interactions. We compare the data with a standard model for the dark halo of our galaxy and also in a halo-independent manner. In our standard-halo analysis, we find that for isospin-conserving couplings, CDMSlite and LUX together exclude the DAMA, CoGeNT, CDMS-II-Si, and CRESST-II possible WIMP signal regions. For isospin-violating couplings instead, we find that a substantial portion of the CDMS-II-Si region is compatible with all exclusion limits. In our halo-independent analysis, we find that for isospin-conserving couplings, the situation is of strong tension between the positive and negative results, as it was before the LUX and CDMSlite bounds, which turn out to exclude the same possible WIMP signals as previous limits. For isospin-violating couplings, we find that LUX and CDMS-II-Si bounds together exclude or severely constrain the DAMA, CoGeNT and CRESST-II possible WIMP signals.

Mathematical model of the Lux luminescence system in the terrestrial bacterium Photorhabdus luminescens

A mathematical model of the Lux luminescence system, governed by the operon luxCDABE in the terrestrial bacterium Photorhabdus luminescens, was constructed using a set of coupled ordinary differential equations. This model will have value in the interpretation of Lux data when used as a reporter in time-course gene expression experiments. The system was tested on time series and stationary data from published papers and the model is in good agreement with the published data. Metabolic control analysis demonstrates that control of the system lies mainly with the aldehyde recycling pathway (LuxE and LuxC). The rate at which light is produced in the steady state model shows a low sensitivity to changes in kinetic parameter values to those measured in other species of luminescent bacteria, demonstrating the robustness of the Lux system.

TU‐FF‐A3‐04: Impact of Room Illuminance On Black Level Luminance and Contrast Detection for Off‐Axis Viewing On High Resolution Normal and High‐Bright Flat Panel Displays

Purpose: Flat panel display image quality is known to be highly dependent on viewing angle. The contribution of room illuminance to black level luminance is well understood for CRTs, but, is not clearly understood for flat panel displays. We have investigated the effect of room illuminance and off axis viewing on displayed image quality. Two high resolution 9.2 megapixel flat panels were evaluated under various room illuminance levels and viewing angles — a standard IBM T221. Method and Materials: Black level luminance was measured at 0, ±15, ±30 and ±45 degrees with room illuminance levels of 0, 2, 5, 10 and 50 lux. Luminance was measured with a Minolta LA‐100a spot meter and illuminance levels were measured with an International Light Luminance Meter IL 1400a. The luminance target (3% of total display area) was centered on the display. Reader studies using a computer generated contrast detail phantom were conducted at each viewing angle and room illuminance level. Five readers read the target images. Specular reflections were minimized for all measurements and reader observations. Results: Minimization of specular reflections in the viewing room minimized the change in measured black level luminance. As room illuminance levels increased and viewing angles became more acute black level luminance increased. Reader results are presented as k‐values and a correlation with room illuminance and black level luminance is demonstrated. The optimal viewing condition was shown to be 0 degrees with a room illuminance of 2 lux. Substantial degradation of measured k‐value and black level luminance occurred at other viewing conditions. Conclusion: Visual perception of small targets is substantially impacted by both viewing angle and room illuminance. The results of these measurements help to explain the observed variations in 5 and 50 lux data presented at the Pittsburgh AAPM meeting.