arXiv subjects

Marek Matas

Publications and source records attributed to Marek Matas.

14 recordsLinked to original sources

arXiv2026

Towards Quantum-Dot Detectors as Barcodes for Dark Matter Interactions

Quantum dots are tunable semiconductor nanocrystals that can be produced at industrial scales. We present the first ab initio calculation of the scattering of dark matter on electrons bound in quantum dots. The momentum-dependence of a quantum dot's electronic response depends on its morphology and on the dark matter mass, interaction operator, mediator coupling, and mediator mass. Therefore, the relative rates across an array of distinct quantum dot targets form a ``barcode'' that carries information about the nature of the dark matter interaction. We project the sensitivity of a detector concept in which a collection of independent target subunits, each loaded with silicon quantum dots of a particular morphology, are read out by Skipper CCDs. Given a future signal, this barcode could discriminate between interaction operators and mediator types. We quantify the discrimination power for a benchmark pair of models as a function of readout noise and exposure.

hep-ph↗

arXiv2026

Dynamical multiferroicity in framework materials

Dynamical multiferroicity, which describes the magnetic fields generated by circularly polarized phonons in materials, is an established mechanism for optical control of magnetism. Here we perform ab initio calculations of dynamical multiferroicity in inorganic and organic framework materials, with the goal of identifying materials which enable the generation of large magnetic fields by light. We find the metal--organic framework material Zn(NH$_4$)(formate)$_3$ to have modes with magnetic moments almost twice that of SrTiO$_3$; these modes involve circular motions of NH$_4^+$ hydrogen ions with high gyromagnetic ratios. The complex structure and flexibility of framework materials can allow such angular momentum localization, and also increase the maximum light-induced magnetization permitted by the Lindemann melting criterion.

cond-mat.mtrl-sci↗

arXiv2026

Zero Indirect Band Gap and Flat Bands in a Niobium Oxyiodide Cluster Material

Explorative chemistry in a reaction system composed of NbI$_4$, Li$_2$(CN$_2$), and Li$_2$O has led to the discovery of a number of niobium oxyiodide cluster compounds. During this reaction, the formation of solid phases was detected alongside with gaseous phases, resulting in a range of products with cluster cores of varying shapes. After several niobium oxyiodide cluster compounds have already been identified within this reaction system, two additional compounds, Nb$_6$O$_3$I$_{15}$ and Nb$_{11}$O$_6$I$_{24}$, are discovered and structurally characterized by single-crystal X-ray diffraction. Both structures are based on the butterfly-shaped, oxygen-capped niobium cluster [Nb$_4$O], which is extended to larger cluster fragments. The [Nb$_4$O] cluster core in Nb$_6$O$_3$I$_{15}$is extended by two [NbO] units to form a three-dimensional framework, and Nb$_{11}$O$_6$I$_{24}$ contains two connected [Nb$_4$O] units, which form chiral units within an antiferrochiral hexagonal packing of strings. The striking string-like character of Nb$_{11}$O$_6$I$_{24}$ was investigated in terms of its electronic structure and properties. DFT calculations showed Nb$_{11}$O$_6$I$_{24}$ to possess a zero indirect band gap, with a pair of 3-dimensional flat bands surrounding the Fermi level. These unusual features of the electronic band structure suggest the presence of strongly correlated inter-cluster singlet electron states, arising from the helical shape of the clusters, the hexagonal packing of the strings, and the delocalized nature of cluster electron wavefunctions.

cond-mat.str-el↗

arXiv2025

Chiral phonons in metal-organic frameworks as quantum sensors for the direct detection of dark matter

We investigate a new quantum sensor for dark matter direct detection with sub-eV sensitivity, focusing on several candidate materials that potentially host chiral phonons with large magnetic moments that can be directly read out with an external magnetometer. We focus on metal-organic frameworks (MOFs) as possible candidate materials for single chiral phonon detection due to their noncentrosymmetric structure, tunability, and the ability to host these excitations in stable acoustic bands. We identify several promising candidates and compare their projected dark matter detection sensitivity for all possible interactions identified within effective field theory. We establish that the expected sensitivity does not depend heavily on the specific choice of the MOF, enabling us to tailor the final material composition to facilitate the magnetic readout. We then propose a prototype setup able to test the direct readout of a chiral phonon sensor with a surface-integrated magnetometer.

hep-ph↗

arXiv2025

Electronic structure of liquid xenon in the context of light dark matter direct detection

We present a description of the electronic structure of xenon within the density-functional theory formalism with the goal of accurately modeling dark-matter-induced ionisation in liquid xenon detectors. We compare the calculated electronic structures of the atomic, liquid and crystalline solid phases, and find that the electronic charge density and its derivatives in momentum space are similar in the atom and the liquid, consistent with the weak interatomic van der Waals bonding. The only notable difference is a band broadening of the highest occupied $5p$ levels, reflected in the densities of states of the condensed phases, as a result of the inter-atomic interactions. We therefore use the calculated density of states of the liquid phase, combined with the standard literature approach for the isolated atom, to recompute ionisation rates and exclusion limit curves for the XENON10 and XENON1T experiments. We find that the broadening of the 5$p$ levels induced by the liquid phase is relevant only for dark matter masses below 6 MeV, where it increases the ionisation rate relative to that of the isolated atom. For most of the explored mass range, the energies of the discrete 4$d$ and 5$s$ levels have the strongest effect on the rate. Our findings suggest a simple scheme for calculating dark matter-electron scattering rates in liquid noble gas detectors, using the calculated values for the atom weighted by the density of states of the condensed phase.

hep-ph↗

arXiv2023

Incoherent ${\rm J}/\psi$ production at large $|t|$ identifies the onset of saturation at the LHC

We predict that the onset of gluon saturation can be uniquely identified using incoherent ${\rm J}/\psi$ production in Pb$\unicode{x2013}$Pb collisions at currently accessible energies of the LHC. The diffractive incoherent photo-production of a ${\rm J}/\psi$ vector meson off a hadron provides information on the partonic structure of the hadron. Within the Good-Walker approach it specifically measures the variance over possible target configurations of the hadronic colour field. For this process then, gluon saturation sets in when the cross section reaches a maximum, as a function of the centre-of-mass energy of the photon-hadron system ($W$), and then decreases. We benchmark the energy-dependent hot-spot model against data from HERA and the LHC and demonstrate a good description of the available data. We show that the study of the energy dependence of the incoherent production of ${\rm J}/\psi$ allows us to pinpoint the onset of saturation effects by selecting the region of Mandelstam-$t$ around 1 GeV$^2$ where the contribution of hot spots is dominant. We predict the onset of saturation in a Pb target to occur for $W$ around a few hundred GeV. This can be measured with current data in ultra-peripheral Pb$\unicode{x2013}$Pb collisions at the LHC.

hep-ph↗

arXiv2023

Direct searches for general dark matter-electron interactions with graphene detectors: Part I. Electronic structure calculations

We develop a formalism to describe electron ejections from graphene-like targets by dark matter (DM) scattering for general forms of scalar and spin 1/2 DM-electron interactions and compare their applicability and accuracy within the density functional theory (DFT) and tight binding (TB) approaches. This formalism allows for accurate prediction of the daily modulation signal expected from DM in upcoming direct detection experiments employing graphene sheets as the target material. A key result is that the physics of the graphene sheet and that of the DM and the ejected electron factorise, allowing for the rate of ejections from all forms of DM to be obtained with a single graphene response function. We perform a comparison between the TB and DFT approaches to modeling the initial state electronic wavefunction within this framework, with DFT emerging as the more self-consistent and reliable choice due to the challenges in the embedding of an appropriate atomic contribution into the TB approach.

hep-ph↗

arXiv2023

Direct searches for general dark matter-electron interactions with graphene detectors: Part II. Sensitivity studies

We use a formalism that describes electron ejections from graphene-like targets by dark matter (DM) scattering for general forms of scalar and spin 1/2 DM-electron interactions in combination with state-of-the-art density functional calculations to produce predictions and reach estimates for various possible carbon-based detector designs. Our results indicate the importance of a proper description of the target electronic structure. In addition, we find a strong dependence of the predicted observed signal for different DM candidate masses and interaction types on the detailed geometry and design of the detector. Combined with directional background vetoing, these dependencies will enable the identification of DM particle properties once a signal has been established.

hep-ph↗

arXiv2023

Chiral phonons as dark matter detectors

We propose a method for detecting single chiral phonons that will enable their use as dark-matter detectors. We suggest metal--organic frameworks (MOFs) as detector materials, as their flexibility yields low-energy chiral phonons with measurable magnetic moments, and their anisotropy leads to directional sensitivity, which mitigates background contamination. To demonstrate our proposal, we calculate the phononic structure of the MOF InF$_3$($4,4'$-bipyridine), and show that it has highly chiral acoustic phonons. Detection of such chiral phonons via their magnetic moments would dramatically lower the excitation energy threshold for dark matter detection to the energy of a single phonon. We show that single phonon detection in a MOF would extend detector reach ten or more orders of magnitude below current limits, enabling exploration of a multitude of as-yet-unprobed dark matter candidates.

hep-ph↗

arXiv2022

Dark matter - electron interactions in materials beyond the dark photon model

The search for sub-GeV dark matter (DM) particles via electronic transitions in underground detectors attracted much theoretical and experimental interest in the past few years. A still open question in this field is whether experimental results can in general be interpreted in a framework where the response of detector materials to an external DM probe is described by a single ionisation or crystal form factor, as expected for the so-called dark photon model. Here, ionisation and crystal form factors are examples of material response functions: interaction-specific integrals of the initial and final state electron wave functions. In this work, we address this question through a systematic classification of the material response functions induced by a wide range of models for spin-0, spin-1/2 and spin-1 DM. We find several examples for which an accurate description of the electronic transition rate at DM direct detection experiments requires material response functions that go beyond those expected for the dark photon model. This concretely illustrates the limitations of a framework that is entirely based on the standard ionisation and crystal form factors, and points towards the need for the general response-function-based formalism we pushed forward recently [1,2]. For the models that require non-standard atomic and crystal response functions, we use the response functions of [1,2] to calculate the DM-induced electronic transition rate in atomic and crystal detectors, and to present 90% confidence level exclusion limits on the strength of the DM-electron interaction from the null results reported by XENON10, XENON1T, EDELWEISS and SENSEI.

hep-ph↗

arXiv2021

Crystal responses to general dark matter-electron interactions

We develop a formalism to describe the scattering of dark matter (DM) particles by electrons bound in crystals for a general form of the underlying DM-electron interaction. Such a description is relevant for direct-detection experiments of DM particles lighter than a nucleon, which might be observed in operating DM experiments via electron excitations in semiconductor crystal detectors. Our formalism is based on an effective theory approach to general non-relativistic DM-electron interactions, including the anapole, and magnetic and electric dipole couplings, combined with crystal response functions defined in terms of electron wave function overlap integrals. Our main finding is that, for the usual simplification of the velocity integral, the rate of DM-induced electronic transitions in a semiconductor material depends on at most five independent crystal response functions, four of which were not known previously. We identify these crystal responses, and evaluate them using density functional theory for crystalline silicon and germanium, which are used in operating DM direct detection experiments. Our calculations allow us to set 90% confidence level limits on the strength of DM-electron interactions from data reported by the SENSEI and EDELWEISS experiments. The novel crystal response functions discovered in this work encode properties of crystalline solids that do not interact with conventional experimental probes, suggesting the use of the DM wind as a probe to reveal new kinds of hidden order in materials.

hep-ph↗

arXiv2020

Magnetic field inside of a nucleon and the quark-Zeeman effect

Zeeman effect has been an invaluable tool for the detection and measurement of the effects of a magnetic field on the internal behavior of atoms and nuclei. Along with M\"{o}ssbauer effect, it has been used to determine the magnitude of the magnetic field present in nuclei of atoms but has not been detected inside nucleons so far. In this work, we present a possible signature of the Zeeman-like effect in nucleons that one can extract from the parton distributions with the use of statistical models and Fermi-Dirac distribution. These effects in turn---if electromagnetically dominated---predict the presence of magnetic fields of an unprecedented magnitude inside protons.

hep-ph↗

arXiv2020

Contribution of the non-linear term in the Balitsky-Kovchegov equation to the nuclear structure functions

In this paper, we present nuclear structure functions calculated from the impact-parameter dependent solution of the Balitsky-Kovchegov equation with our recently proposed set of nuclear initial conditions. We calculate the results with and without the non-linear term in the BK equation in order to study the impact of saturation effects on the measurable structure functions and nuclear modification factor. The difference of these results rises with decreasing Bjorken $x$ and increasing scale. These predictions are of interest to the physics program at the future ep and eA colliders.

hep-ph↗

arXiv2018

Forward di-hadron back-to-back correlations in $\boldsymbol{pA}$ collisions from rcBK evolution

We study the disappearance of the away-side peak of the di-hadron correlation function in p+A vs p+p collisions at forward rapidities, when the scaterring process presents a manifest dilute-dense asymmetry. We improve the state-of-the-art description of this phenomenon in the framework of the Color Glass Condensate (CGC), for hadrons produced nearly back-to-back. In that case, the gluon content of the saturated nuclear target can be described with transverse-momentum-dependent gluon distributions, whose small-$x$ evolution we calculate numerically by solving the Balitsky-Kovchegov equation with running coupling corrections. We first show that our formalism provides a good description of the disappearance of the away-side azimuthal correlations in d+Au collisions observed at BNL Relativistic Heavy Ion Collider (RHIC) energies. Then, we predict the away-side peak of upcoming p+Au data at $~\sqrt[]{s}=200$ GeV to be suppressed by about a factor 2 with respect to p+p collisions, and we propose to study the rapidity dependence of that suppression as a complementary strong evidence of gluon saturation in experimental data.

hep-ph↗