Replaced with revised version; new references; new figures, 13 two-column Latexed pages; 11 captioned figures (total 15 individual figures); matches version accepted for publication in PRD
It has been known that neutrinos from supernova (SN) bursts can give rise to nuclear recoil (NR) signals arising from coherent elastic neutrino-nucleus scattering (CE$ν$NS) interaction, a neutral current (NC) process, of the neutrinos with xenon nuclei in future large (multi-ton scale) liquid xenon (LXe) detectors employed for dark matter search, depending on the SN progenitor mass and distance to the SN. In this paper, we show that the same detectors will also be sensitive to inelastic charged current (CC) interactions of the SN electron neutrinos ($ν_e$CC) with the xenon nuclei. Such interactions, while creating an electron in the final state, also leave the post-interaction target nucleus in an excited state, the subsequent deexcitation of which produces, among other particles, gamma rays and neutrons. The electron and deexcitation gamma rays will give ``electron recoil" (ER) type signals, while the deexcitation neutrons produce, through their multiple scattering on the xenon nuclei, further xenon nuclear recoils that will also give NR signals (in addition to those produced through the CE$ν$NS interactions). We discuss the observable scintillation and ionization signals associated with SN neutrino induced CE$ν$NS and $ν_e$CC events in a generic LXe detector and argue that upcoming sufficiently large LXe detectors should be able to detect both these types of events due to neutrinos from reasonably close by SN bursts. We also note that since the total CC induced ER and NR signals receive contributions predominantly from $ν_e$CC interactions while the CE$ν$NS contribution comes from NC interactions of {\emph all the six species of neutrinos}, identification of the $ν_e$CC and CE$ν$NS origin events may offer the possibility of extracting useful information about the distribution of the total SN explosion energy going into different neutrino flavors.
We consider a novel scenario of dark photon-mediated inelastic dark matter to explain the white dwarf cooling excess suggested by its luminosity function, and the excess in electron recoil events at XENON1T. In the Sun, the dark photon $A'$ is produced mainly via thermal processes, and the heavier dark matter $χ_2$ is produced by the scattering of halo dark matter $χ_1$ with electrons. The XENON1T signal arises primarily by solar $A'$ scattering, and $A'$ emission by white dwarfs accommodates the extra cooling while maintaining consistency with other stellar cooling observations. A tritium com…
Dark matter detectors that utilize liquid xenon have now achieved tonne-scale targets, giving them sensitivity to all flavours of supernova neutrinos via coherent elastic neutrino-nucleus scattering. Considering for the first time a realistic detector model, we simulate the expected supernova neutrino signal for different progenitor masses and nuclear equations of state in existing and upcoming dual-phase liquid xenon experiments. We show that the proportional scintillation signal (S2) of a dual-phase detector allows for a clear observation of the neutrino signal and guarantees a particularly …
Dark matter can scatter and excite a nucleus to a low-lying excitation in a direct detection experiment. This signature is distinct from the canonical elastic scattering signal because the inelastic signal also contains the energy deposited from the subsequent prompt de-excitation of the nucleus. A measurement of the elastic and inelastic signal will allow a single experiment to distinguish between a spin-independent and spin-dependent interaction. For the first time, we characterise the inelastic signal for two-phase xenon detectors in which dark matter inelastically scatters off the Xe-129 o…
Fully understanding the average core-collapse supernova requires detecting the diffuse supernova neutrino background (DSNB) in all flavors. While the DSNB $\barν_e$ flux is near detection, and the DSNB $ν_e$ flux has a good upper limit and prospects for improvement, the DSNB $ν_x$ (each of $ν_μ, ν_τ, \barν_μ, \barν_τ$) flux has a poor limit and heretofore had no clear path for improved sensitivity. We show that a succession of xenon-based dark matter detectors -- XENON1T (completed), XENONnT/LUX-ZEPLIN (running), and DARWIN (proposed) -- can dramatically improve sensitivity to DSNB $ν_x$ the n…
Inelastic from the Other Side: Xenon Excitation Signals in Light of the LZ High-Recoil Event
Nanjing Normal University（南京师范大学）；Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）；Xinjiang University（新疆大学）
We propose a self-interacting inelastic dark matter (DM) scenario as a possible origin of the recently reported excess of electron recoil events by the XENON1T experiment. Two quasi-degenerate Majorana fermion DM interact within themselves via a light hidden sector massive gauge boson and with the standard model particles via gauge kinetic mixing. We also consider an additional long-lived singlet scalar which helps in realising correct dark matter relic abundance via a hybrid setup comprising of both freeze-in and freeze-out mechanisms. While being consistent with the required DM phenomenology…
Measuring dark matter (DM) signals via electron recoil provides an important means for direct detection of light DM particles. The recent XENON1T anomaly with electron recoil energy around $\,E_R^{}\!=\!(2-3)$keV can be naturally explained by DM inelastic scattering which injects energy to the recoiled electrons and gives a narrow peak structure in the recoil spectrum. We present an effective field theory (EFT) approach to exothermic inelastic DM signals for the Xenon electron recoil detection. For relatively heavy mediator, we fairly formulate the DM-lepton interactions by effective contact o…
Detection of electron recoils by dark matter (DM) may reveal the structure of the dark sector. We consider a scenario where a heavier DM particle inelastically scatters off an electron and is converted into a lighter DM particle. A small mass difference between the two DM particles is transferred into electron recoil energy. We investigate the DM-electron interaction mediated by a massive dark photon and evaluate the inelastic DM scattering rate, taking account of the atomic structure. It is found that the scattering rate is significantly enhanced because of the small mass splitting, which all…
Motivated by the recently reported excess in electron recoil events by the XENON1T collaboration, we propose an inelastic fermion dark matter (DM) scenario within the framework of a gauged $L_μ-L_τ$ extension of the standard model which can also accommodate tiny neutrino masses as well as anomalous muon magnetic moment $(g-2)_μ$. A Dirac fermion DM, naturally stabilised due to its chosen gauge charge, is split into two pseudo-Dirac mass eigenstates due to Majorana mass term induced by singlet scalar which also takes part in generating right handed neutrino masses responsible for type I seesaw …
We study a generic model in which the dark sector is composed of a Majorana dark matter $χ_1$, its excited state $χ_2$, both at the electroweak scale, and a light dark photon $Z'$ with $m_{Z'} \sim 10^{-4}$ eV. The light $Z'$ enhances the self-scattering elastic cross section $χ_1 χ_1 \to χ_1 χ_1$ enough to solve the small scale problems in the $N$-body simulations with the cold dark matter. The dark matter communicates with the SM via kinetic mixing parameterized by $ε$. The inelastic scattering process $χ_1 χ_1 \to χ_2 χ_2$ followed by the prompt decay $χ_2 \to χ_1 Z'$ generates energetic $Z…
It has been suggested that dark matter particles which scatter inelastically from detector target nuclei could explain the apparent incompatibility of the DAMA modulation signal (interpreted as evidence for particle dark matter) with the null results from CDMS-II and XENON10. Among the predictions of inelastically interacting dark matter are a suppression of low-energy events, and a population of nuclear recoil events at higher nuclear recoil equivalent energies. This is in stark contrast to the well-known expectation of a falling exponential spectrum for the case of elastic interactions. We p…
In 2020 the XENON1T experiment observed an excess of events with an electron recoil energy $E_R$ in the range of $2\,$--$\,3\,$keV. Such an excess can arise from a variety of sources such as solar axions or a neutrino magnetic moment, but also from inelastic scattering of dark matter off the xenon atoms. The recoil energy of the electron then depends on the mass difference of the dark particles. In this paper we show that the annual modulation of both the event rate and the electron recoil energy provide important additional information that allows to distinguish among different theoretical ex…
We propose a new candidate of GeV scale inelastic dark matter (DM). Our construction has an anomaly-free $U(1)_X^{}$ gauge group with dark photon mediator, and can realize either scalar or fermionic inelastic DM. It is highly predictive and testable. We study the scattering rate of light inelastic DM with electrons in the XENON1T experiment and with nuclei in the XENON1T, CRESST-III, CDEX-1B and DarkSide-50 experiments. We resolve the recent XENON1T anomaly via electron recoil detection. Combining the XENON1T constraints from both electron recoils and nuclear recoils (including Migdal effect),…
A very economic scenario with just three extra scalar fields beyond the Standard Model is invoked to explain the muon anomalous magnetic moment, the requisite relic abundance of dark matter as well as the Xenon-1T excess through the inelastic down-scattering of the dark scalar.
The XENON100 and CRESST experiments will directly test the inelastic dark matter explanation for DAMA's 8.9? sigma anomaly. This article discusses how predictions for direct detection experiments depend on uncertainties in quenching factor measurements, the dark matter interaction with the Standard Model and the halo velocity distribution. When these uncertainties are accounted for, an order of magnitude variation is found in the number of expected events at CRESST and XENON100.
Iodine is distinguished from other elements used in dark matter direct detection experiments both by its large mass as well as its large magnetic moment. Inelastic dark matter utilizes the large mass of iodine to allay tensions between the DAMA annual modulation signature and the null results from other experiments. We explore models of inelastic dark matter that also take advantage of the second distinct property of iodine, namely its large magnetic moment. In such models the couplings are augmented by magnetic, rather than merely electric, interactions. These models provide simple examples w…
For Whom the Xenon Recoils: Magnetic Inelastic Dark Baryons
University of California Santa Cruz（加州大学圣克鲁兹分校）；California Institute of Technology（加州理工学院）；Fermilab（费米国家加速器实验室）；University of Pittsburgh（匹兹堡大学）；University of Oregon（俄勒冈大学）
We consider searches for the inelastic scattering of low-mass dark matter at direct detection experiments, using the Migdal effect. We find that there are degeneracies between the dark matter mass and the mass splitting that are difficult to break. Using XENON1T data we set bounds on a previously unexplored region of the inelastic dark matter parameter space. For the case of exothermic scattering, we find that the Migdal effect allows xenon-based detectors to have sensitivity to dark matter with ${\cal O}(\mathrm{MeV})$ mass, far beyond what can be obtained with nuclear recoils alone.
The identity of dark matter is being sought with increasingly sensitive and voluminous underground detectors. Recently the XENON1T collaboration reported excess electronic recoil events, with most of these having recoil energies around $1-30$ keV. We show that a straightforward model of inelastic dark matter produced via early universe thermal freeze-out annihilation can account for the XENON1T excess. Remarkably, this dark matter model consists of a few simple elements: sub-GeV mass Dirac fermion dark matter coupled to a lighter dark photon kinetically mixed with the Standard Model photon. A …
The growing interest in the interactions between dark matter particles and electrons has received a further boost by the observation of an excess in electron recoil events in the XENON1T experiment. Of particular interest are dark matter models in which the scattering process is inelastic, such that the ground state can upscatter into an excited state. The subsequent exothermic downscattering of such excited states on electrons can lead to observable signals in direct detection experiments and gives a good fit to the XENON1T excess. In this work, we study terrestrial upscattering, i.e. inelast…
Dark Matter particles can be detected directly via their elastic scattering with nuclei. Next generation experiments can eventually find physical evidences about dark matter candidates. With this motivation in mind, we have calculated the expected signals of dark matter particles in xenon detectors. The calculations were performed by considering different masses and parameters within the minimal supersymmetric standard model. Since the detectors can also detect neutrinos, we have analyzed the supernova neutrino signal including a sterile neutrino in the formalism. Using this 3+1 scheme, we mak…
The XENON1T dark matter experiment recently reported 0.65 ton-year exposure measurement on electron recoils , which shows an excess in $2\sim 3$ KeV recoils above the detector background. In this paper we present a Pseudo-Dirac dark matter scenario to explain the excess via inelastic dark matter-electron scattering. With a KeV scale mass splitting between the two components of the Pseudo-Dirac dark matter, the slightly excited component can down-scatter on electrons. The desired dark matter masses are about 10 GeV with a 4 KeV mass-splitting and unity coupling to electrons, which generate the …
We revisit the signatures from collisions of cosmic-rays on sub-GeV dark matter (DM) in the Milky Way. In addition to the upscattered DM component that can be probed by existing DM and neutrino experiments widely discussed, we examine the associated signals in $γ$-rays and neutrinos that span a wide energy range due to the inelastic scatterings. Assuming a simple vector portal DM model for illustration, we compute both the upscattered DM flux by cosmic-ray protons, and the resulting emission of secondary $γ$-rays and high-energy neutrinos from proton excitation, hadronization, and the subseque…
We present halo-independent methods to analyze the results of dark matter direct detection experiments assuming inelastic scattering. We focus on the annual modulation signal reported by DAMA/LIBRA and present three different halo-independent tests. First, we compare it to the upper limit on the unmodulated rate from XENON100 using (a) the trivial requirement that the amplitude of the annual modulation has to be smaller than the bound on the unmodulated rate, and (b) a bound on the annual modulation amplitude based on an expansion in the Earth's velocity. The third test uses the special predic…
Direct detection experiments relying on nuclear recoil signatures lose sensitivity to sub-GeV dark matter for typical galactic velocities. This sensitivity is recovered if there exists another source of flux with higher momenta. Such an energetic flux of light dark matter could originate from the decay of mesons produced in inelastic cosmic ray collisions. We compute this novel production mechanism---a cosmic beam dump experiment---and estimate the resulting limits from XENON1T and LZ. We find that the dark matter flux from inelastic cosmic rays colliding with atmospheric nuclei can dominate o…
There exist well motivated models of particle dark matter which predominantly scatter inelastically off nuclei in direct detection experiments. This inelastic transition causes the DM to up-scatter in terrestrial experiments into an excited state up to 550 keV heavier than the DM itself. An inelastic transition of this size is highly suppressed by both kinematics and nuclear form factors. We extend previous studies of inelastic DM to determine the present bounds on the scattering cross section, and the prospects for improvements in sensitivity. Three scenarios provide illustrative examples: ne…
We present a particle physics model to explain the observed enhancement in the Xenon-1T data at an electron recoil energy of 2.5 keV. The model is based on a $U(1)$ extension of the Standard Model where the dark sector consists of two essentially mass degenerate Dirac fermions in the sub-GeV region with a small mass splitting interacting with a dark photon. The dark photon is unstable and decays before the big bang nucleosynthesis, which leads to the dark matter constituted of two essentially mass degenerate Dirac fermions. The Xenon-1T excess is computed via the inelastic exothermic scatterin…
Mirror dark matter, where dark matter resides in a hidden sector exactly isomorphic to the standard model, can be probed via direct detection experiments by both nuclear and electron recoils if the kinetic mixing interaction exists. In fact, the kinetic mixing interaction appears to be a prerequisite for consistent small scale structure: Mirror dark matter halos around spiral galaxies are dissipative - losing energy via dark photon emission. This ongoing energy loss requires a substantial energy input, which can be sourced from ordinary supernovae via kinetic mixing induced processes in the su…
We show that the current sensitivities of direct detection experiments have already reached the interesting parameter space of freeze-in dark matter models if the dark sector is in the inelastic dark matter framework and the excited dark matter state is cosmologically stable. Using results recently presented by the XENON1T experiment, we present constraints on these models. We also show that these models can explain the reported excess in the electron recoil signals if the mass gap between the ground state and the excited state is at keV scale.
We reanalyze the annual modulation data observed by CoGeNT experiment and show that if the annually modulated anomaly detected by CoGeNT is induced by collision between dark matter particle and nucleus, it can be fitted by a $Z'$ model with inelastic dark matter and isospin-violating interaction, and the constraint from XENON100 can be avoided. This $Z'$ model is strongly constrained by collider physics that the upper bound of the mass of $Z'$ is around twice of the mass of dark matter.
We perform a fit to the recent Xenon100 data and study its implications for Dark Matter scenarios. We find that Inelastic Dark Matter is disfavoured as an explana- tion to the DAMA/LIBRA annual modulation signal. Concerning the scalar singlet DM model, we find that the Xenon100 data disfavors its constrained limit. We study the CMSSM as well as the low scale phenomenological MSSM taking into account latest Tevatron and LHC data (1.1/fb) about sparticles and Bs \rightarrow μμ. After the EPS 2011 conference, LHC excludes the "Higgs-resonance" region of DM freeze-out and Xenon100 disfavors the "w…
The production of charged hadrons, in muon Deep inelastic scattering (DIS), at light and heavy target is presented. The particles produced by the interaction with Xenon (Xe) is compared with that produced by the interaction with Deuteron (D), to obtain information on cascading process, forward-backward productions, and the rapidity distribution in different bins of the invariant mass of the interacting system W.
We study luminous dark matter signals in models with inelastic scattering. Dark matter $χ_1$ that scatters inelastically off elements in the Earth is kicked into an excited state $χ_2$ that can subsequently decay into a monoenergetic photon inside a detector. The photon signal exhibits large sidereal-daily modulation due to the daily rotation of the Earth and anisotropies in the problem: the dark matter wind comes from the direction of Cygnus due to the Sun's motion relative to the galaxy, and the rock overburden is anisotropic, as is the dark matter scattering angle. This allows outstanding s…
Inelastic dark matter, in which WIMP-nucleus scatterings occur through a transition to an excited WIMP state ~ 100 keV above the ground state, provides a compelling explanation of the DAMA annual modulation signal. We demonstrate that the relative sensitivities of various dark matter direct detection experiments are modified such that the DAMA annual modulation signal can be reconciled with the absence of a reported signal at CDMS-Soudan, XENON10, ZEPLIN, CRESST, and KIMS for inelastic WIMPs with masses O(100 GeV). We review the status of these experiments, and make predictions for upcoming on…
The nature of dark matter (DM) particles and the mechanism that provides their measured relic abundance are currently unknown. In this paper we investigate inert scalar and vector like fermion doublet DM candidates with a charge asymmetry in the dark sector, which is generated by the same mechanism that provides the baryon asymmetry, namely baryogenesis-via-leptogenesis induced by decays of scalar triplets. At the same time the model gives rise to neutrino masses in the ballpark of oscillation experiments via type II seesaw. We discuss possible sources of depletion of asymmetry in the DM and v…
Recently, the XENON1T experiment has observed an excess in the electronic recoil data in the recoil energy range of $1$-$7$ keV. One of the most favored new physics interpretations is electron scattering with a boosted particle with a velocity of $\sim 0.1$ and a mass of $\gtrsim 0.1\,\mathrm{MeV}$. If such a particle has a strong interaction with electrons, it may affect the standard scenario of cosmology or be observed at low-threshold direct detection experiments. We study various constraints, mainly focusing on those from the big-bang nucleosynthesis, supernova cooling, and direct detectio…
We show that the excess in electron recoil events seen by the XENON1T experiment can be explained by relatively low-mass Luminous Dark Matter candidate. The dark matter scatters inelastically in the detector (or the surrounding rock), to produce a heavier dark state with a ~2.75 keV mass splitting. This heavier state then decays within the detector, producing a peak in the electron recoil spectrum which is a good fit to the observed excess. We comment on the ability of future direct detection datasets to differentiate this model from other Beyond the Standard Model scenarios, and from possible…
We propose an attractive model that excess of electron recoil events around 1-5 keV reported by the XENON1T collaboration nicely links to the tiny neutrino masses based on a radiative seesaw scenario. Our dark matter(DM) is an isospin singlet inert boson that plays an role in generating non-vanishing neutrino mass at one-loop level, and this DM inelastically interacts with a pair of electrons at one-loop level that is required to explain the XENON1T anomaly. It is also demanded that the mass difference between an excited DM and DM has to be of the order keV. Interestingly, the small mass diffe…
Cosmic-ray boosted inelastic dark matter from neutrino-emitting active galactic nuclei
Virginia Tech（弗吉尼亚理工大学）；Massachusetts Institute of Technology（麻省理工学院）；Harvard University（哈佛大学）；The Pennsylvania State University（宾夕法尼亚州立大学）；Fermi National Accelerator Laboratory（费米国家加速实验室）；University of Chicago（芝加哥大学）
The XENON1T collaboration recently reported the excess of events from recoil electrons, possibly giving an insight into new area beyond the Standard Model (SM) of particle physics. We try to explain this excess by considering effective interactions between the sterile neutrinos and the SM particles. In this paper, we present an effective model based on one-particle-irreducible interaction vertices at low energies that are induced from the SM gauge symmetric four-fermion operators at high energies. The effective interaction strength is constrained by the SM precision measurements, astrophysical…
We consider a novel mechanism to realize exothermic dark matter with dark mesons in the limit of approximate flavor symmetry in a dark QCD. We introduce a local dark $U(1)'$ symmetry to communicate between dark mesons and the Standard Model via $Z'$ portal by partially gauging the dark flavor symmetry with flavor-dependent charges for cancelling chiral anomalies in the dark sector. After the dark local $U(1)'$ is broken spontaneously by the VEV of a dark Higgs, there appear small mass splittings between dark quarks, consequently, leading to small split masses for dark mesons, required to expla…
Very recently, the Xenon1T collaboration has reported an intriguing electron recoil excess, which may imply for light dark matter. In order to interpret this anomaly, we propose the atmospheric dark matter (ADM) from the inelastic collision of cosmic rays (CRs) with the atmosphere. Due to the boost effect of high energy CRs, we show that the light ADM can be fast-moving and successfully fit the observed electron recoil spectrum through the ADM-electron scattering process. Meanwhile, our ADM predicts the scattering cross section $σ_e \sim {\cal O}(10^{-38}- 10^{-39}$) cm$^{2}$, and thus can eva…
Direct dark matter detection focuses on elastic scattering of dark matter particles off nuclei. In this study, we explore inelastic scattering where the nucleus is excited to a low-lying state of 10-100 keV, with subsequent prompt de-excitation. We calculate the inelastic structure factors for the odd-mass xenon isotopes based on state-of-the-art large-scale shell-model calculations with chiral effective field theory WIMP-nucleon currents. For these cases, we find that the inelastic channel is comparable to or can dominate the elastic channel for momentum transfers around 150 MeV. We calculate…
Motivated by the recently reported excess of electron recoil events by the XENON1T experiment, we propose low scale seesaw scenarios for light neutrino masses within $U(1)_X$ gauge extension of the standard model that also predicts stable as well as long lived dark sector particles. The new fields necessary for seesaw realisation as well as dark matter are charged under the $U(1)_X$ gauge symmetry in an anomaly free way. A singlet scalar field which effectively gives rise to lepton number violation and hence Majorana light neutrino masses either at tree or radiative level, also splits the dark…
We study the capture and subsequent annihilation of inelastic dark matter (DM) in the Sun, placing constraints on the DM-nucleon scattering cross section from the null result of the IceCube neutrino telescope. We then compare such constraints with exclusion limits on the same cross section that we derive from XENON1T, PICO and CRESST results. We calculate the cross section for inelastic DM-nucleon scattering within an extension of the effective theory of DM-nucleon interactions which applies to the case of inelastic DM models characterised by a mass splitting between the incoming and outgoing …
Direct detection experiments aim at the detection of dark matter in the form of weakly interacting massive particles (WIMPs) by searching for signals from elastic dark matter nucleus scattering. Additionally, inelastic scattering in which the nucleus is excited is expected from nuclear physics and provides an additional detectable signal. In the context of a low-energy effective field theory we investigate the experimental reach to these inelastic transitions for xenon-based detectors employing a dual-phase time projection chamber. We find that once a dark matter signal is established, inelast…
Proton-philic spin-dependent inelastic Dark Matter is a Weakly Inelastic Massive Particle scenario that can explain the DAMA yearly modulation effect in compliance with the constraints from other direct detection Dark Matter searches. We obtain updated ranges for its parameters both in a halo-independent approach and adopting a truncated Maxwellian for the WIMP velocity distribution constructing approximate frequentist confidence intervals from an effective chi-square including, among others, the latest experimental constraints from XENON1T, PANDAX-II, SuperCDMS and CDMSlite. In the halo-indep…
Dark matter direct detection experiments have poor sensitivity to a galactic population of dark matter with mass below the GeV scale. However, such dark matter can be produced copiously in supernovae. Since this thermally-produced population is much hotter than the galactic dark matter, it can be observed with direct detection experiments. In this paper, we focus on a dark sector with fermion dark matter and a heavy dark photon as a specific example. We first extend existing supernova cooling constraints on this model to the regime of strong coupling where the dark matter becomes diffusively t…
We revisit the detection of luminous dark matter in direct detection experiments. In this scenario, dark matter scatters endothermically to produce an excited state, which decays to produce a photon. We explore ways in which the electron recoil signal from the decay photon can be differentiated from other potential electron recoil signals with a narrow spectral shape. We find that larger volume/exposure xenon detectors will be unable to differentiate the signal origin without significant improvements in detector energy resolution of around an order of magnitude. We also explore what can be lea…
We determine constraints on sterile neutrino warm dark matter through direct detection experiments, taking XENON100, XENON1T and DARWIN as examples. If keV-scale sterile neutrinos scatter inelastically with bound electrons of the target material, an electron recoil signal is generated. This can be used to set limits on the sterile neutrino mass and its mixing with the active sector. While not competitive with astrophysical constraints from X-ray data, the constraints are the first direct laboratory bounds on sterile neutrino warm dark matter, and will be in some parts of parameter space the st…
We present a model independent analysis of inelastic dark matter transitions at direct detection experiments by modifying the elastic methodology of Fitzpatrick, et al. By analyzing the kinematics of inelastic transitions, we find the relevant variables to describe these scattering processes, the primary change being a modification of the $\vec{v}^\perp$ variable. Taking this into account, we list the relevant scattering matrix elements and modify the Mathematica package of Anand, et al. to calculate the necessary form factors. As an application, we determine the matrix elements of inelastic s…
Inspired by a recently proposed model of millicharged atomic dark matter (MADM), we analyze several classes of light dark matter models with respect to CoGeNT modulated and unmodulated data, and constraints from CDMS, XENON10 and XENON100. After removing the surface contaminated events from the original CoGeNT data set, we find an acceptable fit to all these data (but with the modulating part of the signal making a statistically small contribution), using somewhat relaxed assumptions about the response of the null experiments at low recoil energies, and postulating an unknown modulating backgr…
