arXiv subjects

L. Roszkowski

Publications and source records attributed to L. Roszkowski.

At least 19 recordsLinked to original sources

arXiv2026

Measurement of the muon flux at SNOLAB using the DEAP-3600 experiment

A direct measurement of the muon flux at SNOLAB is performed using the DEAP-3600 experiment, located 2 km underground at SNOLAB near Sudbury, Canada. Primarily designed for the direct detection of weakly interacting massive particles (WIMPs), a dark matter candidate, DEAP-3600 consists of an inner spherical acrylic vessel containing a liquid argon target; this vessel is enclosed within a steel shell which is submerged in an instrumented water tank, serving as a muon veto for the dark matter search. The muon flux measurement is performed using a cut-and-count analysis of events observed in the muon veto detector and of events which are coincident between the muon veto and the liquid argon target. The requirement that muons traverse both the water and liquid argon minimizes instrumental backgrounds and systematic uncertainties. Using data collected from November 2016 to March 2020, the muon flux is measured by this coincidence analysis to be $(3.71 \pm 0.25_{\textrm{stat}} \pm 0.09_{\textrm{sys}}) \times 10^{-10}\, \mu/$cm$^2$/s. The standalone measurement using muon veto data only is compatible within uncertainties. Both measurements agree with the previous result by the SNO experiment and with simulations carried out using the MUTE software. These results provide an important benchmark for future rare-event searches at the SNOLAB facility.

hep-ex↗

arXiv2026

First evidence of neutrino absorption on argon using $^{8}$B solar neutrinos in DEAP-3600

We report experimental evidence for electron neutrino charged-current interactions (neutrino absorption, CC $\nu_e$) from $^{8}$B solar neutrinos on $^{40}$Ar using an exposure of ($7.29 \pm 0.05$) tonne$\cdot$years in the DEAP-3600 detector. A region of interest (ROI) of 10.5-13.0 MeV reconstructed energy calibrated on single-peak events, corresponding to incident neutrino energy in 12.0-14.5 MeV, is used for this measurement. We observe 5 single-peak and 1 double-peak neutrino-like events consistent with the $^{8}$B solar neutrino energy spectrum in the ROI after correcting for nonlinearities in the detector response at high energies. With an expected background of $0.48~^{+0.16}_{-0.15}$ events, the data correspond to a significance of $4.0\,\sigma$ with respect to the background-only hypothesis. We report an energy-averaged cross section of $(4.0~^{+2.0}_{-1.6}~\mathrm{(stat)}~^{+0.8}_{-0.7}~\mathrm{(sys)})\times 10^{-41}\,\mathrm{cm}^2$ in the ROI for the CC $\nu_{e}$ signal, a factor $(2.4~^{+1.3}_{-1.0})$ higher than predicted by Bhattacharya, Goodman and Garc\'ia (2009).

hep-ex↗

arXiv2026

Dark Matter Search with the DEAP-3600 Detector using the Profile Likelihood Ratio Method

We present here a search for WIMP dark matter using 790.8 live-days of data collected with 3269 kg of liquid argon (1266 kg fiducial) by the DEAP-3600 detector at SNOLAB, using the Profile Likelihood Ratio method. The likelihood model is based on three parameters: estimated energy, pulse-shape discrimination parameter, and reconstructed position within the detector. Using this method, the expected signal sensitivity of DEAP-3600 benefits from an increased fiducial volume and improved event selection acceptance. Alpha-decays from a small number of dust particulates circulating within the liquid argon target are the dominant source of background events and limit the sensitivity of this search. This result provides improved exclusion upper limits on the WIMP-nucleon spin-independent cross section on liquid argon for WIMP masses between 20 GeV/$c^{2}$ and 100 GeV/$c^{2}$. At 100 GeV/$c^{2}$ the observed limit is 3.4 $\times$ 10$^{-45}$ cm$^2$ at 90% confidence level.

hep-ex↗

arXiv2025

Direct Measurement of the $^{39}$Ar Half-life from 3.4 Years of Data with the DEAP-3600 Detector

The half-life of $^{39}$Ar is measured using the DEAP-3600 detector located 2 km underground at SNOLAB. Between 2016 and 2020, DEAP-3600 used a target mass of (3269 $\pm$ 24) kg of liquid argon distilled from the atmosphere in a direct-detection dark matter search. Such an argon mass also enables direct measurements of argon isotope properties. The decay of $^{39}$Ar in DEAP-3600 is the dominant source of triggers by two orders of magnitude, ensuring high statistics and making DEAP-3600 well-suited for measuring this isotope's half-life. Use of the pulse-shape discrimination technique in DEAP-3600 allows powerful discrimination between nuclear recoils and electron recoils, resulting in the selection of a clean sample of $^{39}$Ar decays. Observing over a period of 3.4 years, the $^{39}$Ar half-life is measured to be $(302 \pm 8_{\rm stat} \pm 6_{\rm sys})$ years. This new direct measurement suggests that the half-life of $^{39}$Ar is significantly longer than the accepted value, with potential implications for measurements using this isotope's half-life as input.

nucl-ex↗

arXiv2024

Relative Measurement and Extrapolation of the Scintillation Quenching Factor of $\alpha$-Particles in Liquid Argon using DEAP-3600 Data

The knowledge of scintillation quenching of $\alpha$-particles plays a paramount role in understanding $\alpha$-induced backgrounds and improving the sensitivity of liquid argon-based direct detection of dark matter experiments. We performed a relative measurement of scintillation quenching in the MeV energy region using radioactive isotopes ($^{222}$Rn, $^{218}$Po and $^{214}$Po isotopes) present in trace amounts in the DEAP-3600 detector and quantified the uncertainty of extrapolating the quenching factor to the low-energy region.

physics.ins-det↗

arXiv2022

Constraints on dark matter-nucleon effective couplings in the presence of kinematically distinct halo substructures using the DEAP-3600 detector

DEAP-3600 is a single-phase liquid argon detector aiming to directly detect Weakly Interacting Massive Particles (WIMPs), located at SNOLAB (Sudbury, Canada). After analyzing data taken during the first year of operation, a null result was used to place an upper bound on the WIMP-nucleon spin-independent, isoscalar cross section. This study reinterprets this result within a Non-Relativistic Effective Field Theory framework, and further examines how various possible substructures in the local dark matter halo may affect these constraints. Such substructures are hinted at by kinematic structures in the local stellar distribution observed by the Gaia satellite and other recent astronomical surveys. These include the Gaia Sausage (or Enceladus), as well as a number of distinct streams identified in recent studies. Limits are presented for the coupling strength of the effective contact interaction operators $\mathcal{O}_1$, $\mathcal{O}_3$, $\mathcal{O}_5$, $\mathcal{O}_8$, and $\mathcal{O}_{11}$, considering isoscalar, isovector, and xenonphobic scenarios, as well as the specific operators corresponding to millicharge, magnetic dipole, electric dipole, and anapole interactions. The effects of halo substructures on each of these operators are explored as well, showing that the $\mathcal{O}_5$ and $\mathcal{O}_8$ operators are particularly sensitive to the velocity distribution, even at dark matter masses above 100 GeV/$c^2$.

astro-ph.CO↗

arXiv2022

First direct detection constraints on Planck-scale mass dark matter with multiple-scatter signatures using the DEAP-3600 detector

Dark matter particles with Planck-scale mass ($\simeq10^{19}\text{GeV}/c^2$) arise in well-motivated theories and could be produced by several cosmological mechanisms. Using a blind analysis of data collected over a 813 d live time with DEAP-3600, a 3.3 t single-phase liquid argon-based dark matter experiment at SNOLAB, a search for supermassive dark matter was performed, looking for multiple-scatter signals. No candidate signal events were observed, leading to the first direct detection constraints on Planck-scale mass dark matter. Leading limits constrain dark matter masses between $8.3\times10^{6}$ and $1.2\times10^{19} \text{GeV}/c^2$, and cross sections for scattering on $^{40}$Ar between $1.0\times10^{-23}$ and $2.4\times10^{-18} \text{cm}^2$. These are used to constrain two composite dark matter models.

astro-ph.CO↗

arXiv2016

Detection prospects of light NMSSM Higgs pseudoscalar via cascades of heavier scalars from vector boson fusion and Higgs-strahlung

A detection at the Large Hadron Collider of a light Higgs pseudoscalar would, if interpreted in a supersymmetric framework, be a smoking gun signature of non-minimal supersymmetry. In this work in the framework of the Next-to-Minimal Supersymmetric Standard Model we focus on vector boson fusion and Higgs-strahlung production of heavier scalars that subsequently decay into pairs of light pseudoscalars. We demonstrate that although these channels have in general very limited reach, they are viable for the detection of light pseudoscalars in some parts of parameter space and can serve as an important complementary probe to the dominant gluon-fusion production mode. We also demonstrate that in a Higgsfactory these channels may reach sensitivities comparable to or even exceeding the gluon fusion channels at the LHC, thus possibly rendering this our best option to discover a light pseudoscalar. It is also worth mentioning that for the singlet dominated scalar this may be the only way to measure its couplings to gauge bosons. Especially promising are channels where the initial scalar is radiated off a W as these events have relatively high rates and provide substantial background suppression due to leptons from the W. We identify three benchmark points that well represent the above scenarios. Assuming that the masses of the scalars and pseudoscalars are already measured in the gluon-fusion channel, the event kinematics can be further constrained, hence significantly improving detection prospects. This is especially important in the Higgs-strahlung channels with rather heavy scalars, and results in possible detection at 200/fb for the most favoured parts of the parameter space.

hep-ph↗

arXiv2015

LHC phenomenology of light pseudoscalars in the NMSSM

After the discovery of the 125 GeV Higgs boson, the Next-to-Minimal Supersymmetric Standard Model (NMSSM) has become more interesting as a model for new physics since new tree-level contributions to the Higgs mass makes it easier to accommodate the relatively high measured value, as compared to the MSSM. One very distinctive feature of the NMSSM is the possible existence of a light singlet-like pseudoscalar. As this pseudoscalar may be lighter than the discovered Higgs boson without conflict with data, it may lead to LHC signatures rather different to what is usually searched for in terms of new physics. In these proceedings we will discuss studies concerning the discoverability of such light pseudoscalars. It is demonstrated that heavier scalars decaying to pairs of pseudoscalars or pseudoscalars and Z bosons may lead to discovery in a large part of the parameter space. This is especially important for the non-SM like of the two lightest scalars, as it may have an almost 100% branching ratio for decay into pairs of pseudoscalars. In such a case the discussed channels might be our only means of discovery, also for the scalar.

hep-ph↗

arXiv2015

Looking for supersymmetry: ~1 Tev WIMP and the power of complementarity in LHC and dark matter searches

Some doubts have been expressed about low energy supersymmetry (SUSY) following the first run of the LHC. In this talk I will try to present a more upbeat view based on data, rather than theoretical expectations. In particular, I will make the following points: (a) in my opinion the most attractive candidate for dark matter (DM) is now the lightest neutralino with mass around 1 TeV and with well defined properties (a nearly pure higgsino). This follows primarily from a combination of the properties of the discovered Higgs boson, in particular its mass close to 125 Gev, and the relic density of dark matter, and is most clearly visible in the context of unified, or constrained, SUSY frameworks, although the DM candidate is quite generic; (b) this DM candidate will be nearly fully tested in forthcoming one-tonne DM underground search detectors; (c) the CMSSM will be nearly fully tested in the next few years by a combination of expected data from LHC experiments and from direct DM searches, as well as potentially also by the Cherenkov Telescope Array; (d) if naturalness plays any real role in SUSY (which remains unclear), then the amount of fine tuning, which is very large in simple models like the CMSSM, can be significantly reduced (even down to 1 in 20) with properly selected boundary conditions at the unification scale; (e) the (g-2) muon anomaly can be accommodated not only in the context of the general MSSM but also of some unified SUSY models with some superpartners to be within reach of the LHC.

hep-ph↗

arXiv2014

3.5 keV x-ray line from decaying gravitino dark matter

Extremely weakly interacting particles like the gravitino may be stable enough on cosmological time scales to constitute a good dark matter candidate even in the presence of R-parity violation. We consider the possibility that the recently identified 3.5 keV x-ray line can be generated in light gravitino decays to neutrinos and photons. We find that this is indeed possible in loop processes induced by trilinear lepton-number-violating couplings. We show that in order to avoid overproduction of gravitinos, the reheating temperature has to be at most around 100 GeV to 1 TeV. Finally we briefly discuss associated LHC phenomenology due to a relatively light gluino and multijet/multilepton events from R-parity violating decays of neutralinos.

hep-ph↗

arXiv2012

Benchmark Models, Planes, Lines and Points for Future SUSY Searches at the LHC

We define benchmark models for SUSY searches at the LHC, including the CMSSM, NUHM, mGMSB, mAMSB, MM-AMSB and p19MSSM, as well as models with R-parity violation and the NMSSM. Within the parameter spaces of these models, we propose benchmark subspaces, including planes, lines and points along them. The planes may be useful for presenting results of the experimental searches in different SUSY scenarios, while the specific benchmark points may serve for more detailed detector performance tests and comparisons. We also describe algorithms for defining suitable benchmark points along the proposed lines in the parameter spaces, and we define a few benchmark points motivated by recent fits to existing experimental data.

hep-ph↗

arXiv2010

Global fits of the Non-Universal Higgs Model

We carry out global fits to the Non-Universal Higgs Model (NUHM), applying all relevant present-day constraints. We present global probability maps for the NUHM parameters and observables (including collider signatures, direct and indirect detection quantities), both in terms of posterior probabilities and in terms of profile likelihood maps. We identify regions of the parameter space where the neutralino dark matter in the model is either bino-like, or else higgsino-like with mass close to 1 TeV and spin-independent scattering cross section ~ 10^{-9}-10^{-8} pb. We trace the occurrence of the higgsino-like region to be a consequence of a mild focusing effect in the running of one of the Higgs masses, the existence of which in the NUHM we identify in our analysis. Although the usual bino-like neutralino is more prominent, higgsino-like dark matter cannot be excluded, however its significance strongly depends on the prior and statistics used to assess it. We note that, despite experimental constraints often favoring different regions of parameter space to the Constrained MSSM, most observational consequences appear fairly similar, which will make it challenging to distinguish the two models experimentally

hep-ph↗

arXiv2010

Efficient reconstruction of CMSSM parameters from LHC data - A case study

We present an efficient method of reconstructing the parameters of the Constrained MSSM from assumed future LHC data, applied both on their own right and in combination with the cosmological determination of the relic dark matter abundance. Focusing on the ATLAS SU3 benchmark point, we demonstrate that our simple Gaussian approximation can recover the values of its parameters remarkably well. We examine two popular non-informative priors and obtain very similar results, although when we use an informative, naturalness-motivated prior, we find some sizeable differences. We show that a further strong improvement in reconstructing the SU3 parameters can by achieved by applying additional information about the relic abundance at the level of WMAP accuracy, although the expected data from Planck will have only a very limited additional impact. Further external data may be required to break some remaining degeneracies. We argue that the method presented here is applicable to a wide class of low-energy effective supersymmetric models, as it does not require to deal with purely experimental issues, eg, detector performance, and has the additional advantages of computational efficiency. Furthermore, our approach allows one to distinguish the effect of the model's internal structure and of the external data on the final parameters constraints.

hep-ph↗

arXiv2009

Are BR(b->s gamma) and (g-2)_muon consistent within the Constrained MSSM?

We employ two different statistical tests to examine whether, in the framework of the Constrained MSSM, the experimentally determined values of BR(b->s gamma) and the anomalous magnetic moment of the muon, (g-2), are consistent with each other. Our tests are designed to compare the theoretical predictions of the CMSSM in data space with the actual measurements, once all of the CMSSM free parameters have been integrated out and constrained using all other available data. We investigate the value of (g-2) as obtained by using e+e- data alone (which shows a ~3sigma discrepancy with the SM prediction) and as obtained based on tau decay data (which shows a much milder, 1sigma discrepancy). We find that one of our tests returns either a statistically inconclusive result or shows weak evidence of tension between BR(b->s gamma) and the e+e- data based value of (g-2). On the other hand, our second test, which is more stringent in this application, reveals that the joint observations of BR(b->s gamma) and (g-2) from e+e- data alone are incompatible within the CMSSM at the ~2sigma level. On the other hand, for both tests we find no significant tension between BR(b->s gamma) and the value of (g-2) evaluated using tau decay data. These results are only weakly dependent on the three different priors that we employ in the analysis. We conclude that, if the discrepancy between the Standard Model and the experimental determinations of (g-2) is confirmed at the 3sigma level, this could be interpreted as strong evidence against the CMSSM.

hep-ph↗

arXiv2008

The impact of priors and observables on parameter inferences in the Constrained MSSM

We use a newly released version of the SuperBayeS code to analyze the impact of the choice of priors and the influence of various constraints on the statistical conclusions for the preferred values of the parameters of the Constrained MSSM. We assess the effect in a Bayesian framework and compare it with an alternative likelihood-based measure of a profile likelihood. We employ a new scanning algorithm (MultiNest) which increases the computational efficiency by a factor ~200 with respect to previously used techniques. We demonstrate that the currently available data are not yet sufficiently constraining to allow one to determine the preferred values of CMSSM parameters in a way that is completely independent of the choice of priors and statistical measures. While b->s gamma generally favors large m_0, this is in some contrast with the preference for low values of m_0 and m_1/2 that is almost entirely a consequence of a combination of prior effects and a single constraint coming from the anomalous magnetic moment of the muon, which remains somewhat controversial. Using an information-theoretical measure, we find that the cosmological dark matter abundance determination provides at least 80% of the total constraining power of all available observables. Despite the remaining uncertainties, prospects for direct detection in the CMSSM remain excellent, with the spin-independent neutralino-proton cross section almost guaranteed above sigma_SI ~ 10^{-10} pb, independently of the choice of priors or statistics. Likewise, gluino and lightest Higgs discovery at the LHC remain highly encouraging. While in this work we have used the CMSSM as particle physics model, our formalism and scanning technique can be readily applied to a wider class of models with several free parameters.

hep-ph↗

arXiv2005

Dark Matter And $B_s \to μ^+ μ^-$ With Minimal $SO_{10}$ Soft SUSY Breaking II

We update and extend to larger masses our previous analysis of the MSSM with minimal $SO_{10}$ [MSO$_{10}$SM] soft SUSY breaking boundary conditions. We find a well--defined, narrow region of parameter space which provides the observed relic density of dark matter, in a domain selected to fit precision electroweak data, including top, bottom and tau masses. The model is highly constrained which allows us to make several predictions. We find the light Higgs mass $m_h \leq 121 \pm 3$ GeV and also upper bounds on the mass of the gluino $\mgluino\lsim3.1$ TeV and lightest neutralino $\mchi\lsim450$ GeV. As the CP odd Higgs mass $m_A$ increases, the region of parameter space consistent with WMAP data is forced to larger values of $M_{1/2}$ and smaller values of $m_h$. Hence, we find an upper bound $m_A \lsim 1.3$ TeV. This in turn leads to lower bounds on ${\rm BR}(B_s\to μ^+ μ^-) > 10^{-8}$ (assuming minimal flavor violation) and on the dark matter spin independent detection cross section $\sigsip > 10^{-9}$ pb. Finally, we extend our previous analysis to include WIMP signals in indirect detection and find prospects for WIMP detection generally much less promising than in direct WIMP searches.

hep-ph↗

arXiv2005

Signatures of Axinos and Gravitinos at Colliders

The axino and the gravitino are well-motivated candidates for the lightest supersymmetric particle (LSP) and also for cold dark matter in the Universe. Assuming that a charged slepton is the next-to-lightest supersymmetric particle (NLSP), we show how the NLSP decays can be used to probe the axino LSP scenario in hadronic axion models as well as the gravitino LSP scenario at the Large Hadron Collider and the International Linear Collider. We show how one can identify experimentally the scenario realized in nature. In the case of the axino LSP, the NLSP decays will allow one to estimate the value of the axino mass and the Peccei-Quinn scale.

hep-ph↗