Experimental Search Research Articles

Vector-like quarks: Status and new directions at the LHC

Experimental searches for vector-like quarks have until now only considered their decays into Standard Model particles. However, various new physics scenarios predict additional scalars, so that these vector-like quarks can decay to new channels. These new channels reduce the branching ratios into Standard Model final states, significantly affecting current mass bounds. In this article, we quantitatively assess the relevance and observability of single and pair production processes of vector-like quarks, followed by decays into both standard and exotic final states. We highlight the importance of large widths and the relative interaction strengths with Standard Model particles and new scalars. Then, we review the post-Moriond 2024 status of these models in light of available LHC data and discuss potential future strategies to enhance the scope of vector-like quark searches.

Recent Results from the FASER Experiment at the LHC

The ForwArd Search ExpeRiment (FASER), is an LHC experiment that aims to: (1) detect and study TeV-energy neutrinos, the most energetic neutrinos ever detected from a humanmade source and (2) search for new light and very weakly interacting particles. The FASER detector is located 480 m downstream of the ATLAS p-p interaction point, along the beam collision axis. FASER was designed, constructed, installed, and commissioned during 2019–2022 and has been taking physics data since the start of LHC Run 3 in July 2022. Recently, FASER reported the first measurement of ve and vμ interaction cross sections at the LHC with its sub-detector FASERv , FASER’s emulsion detector, first results on Axion-Like Particles at FASER and dark photons limits. These results will be reported in this article.

Analysis of air consumption and moving speed by firefighters during full-scale search & rescue experiments in a tunnel

Experiments were carried out in a 420 m long dead-end tunnel to assess air consumption and movement speed. The operation consisted of a 417 m walk to locate and rescue a victim. Seven teams of 5 blindfolded firefighters were sent into the tunnel with a single-bottle SCBA, a stretcher and a mobility cane. 14 firefighters (i.e., 44%) had to use ‘reserve air’. Hence it is not considered safe to carry out such an operation. However, all the crews noticed the sign that they used half of the available air in their bottle, so it is possible to start the S&R operation in a tunnel and safely return at the 175 bar mark. The average time to completion was 35.2 minutes. All crews became better at using the cane, leading to a higher average movement speed (0.50 m/s) out of the tunnel than into the tunnel (0.39 m/s). The average air consumption per walking meter was 2.20 L/m going in and 1.33 L/m going out. The average air consumption rate was 49.9L/min going into the tunnel and 38.9 L/min going out of the tunnel. It is shown that speed plays an important role. Faster firefighters have a lower total air consumption.

Experimental search potential for sbottom via χ̄1± decays at the LHC Run-3 and HL-LHC, in final states with same-sign leptons and multiple jets

Experimental search potential for sbottom via χ̄1± decays at the LHC Run-3 and HL-LHC, in final states with same-sign leptons and multiple jets

Universal moiré buckling of freestanding 2D bilayers

The physics of membranes, a classic subject, acquires new momentum from two-dimensional (2D) materials multilayers. This work reports the surprising results emerged during a theoretical study of equilibrium geometry of bilayers as freestanding membranes. While ordinary membranes are prone to buckle around compressive impurities, we predict that all 2D material freestanding bilayers universally undergo, even if impurity-free, a spontaneous out-of-plane buckling. The moiré network nodes here play the role of internal impurities, the dislocations that join them giving rise to a stress pattern, purely shear in homobilayers and mixed compressive/shear in heterobilayers. That intrinsic stress is, theory and simulations show, generally capable to cause all freestanding 2D bilayers to undergo distortive bucklings with large amplitudes and a rich predicted phase transition scenario. Realistic simulations predict quantitative parameters expected for these phenomena as expected in heterobilayers such as graphene/hBN, [Formula: see text] heterobilayers, and for twisted homobilayers such as graphene, hBN, [Formula: see text]. Buckling then entails a variety of predicted consequences. Mechanically, a critical drop of bending stiffness is expected at all buckling transitions. Thermally, the average buckling corrugation decreases with temperature, with buckling-unbuckling phase transitions expected in some cases, and the buckled state often persisting even above room temperature. Buckling will be suppressed by deposition on hard attractive substrates, and survives in reduced form on soft ones. Frictional, electronic, and other associated phenomena are also highlighted. The universality and richness of these predicted phenomena strongly encourages an experimental search, which is possible but still missing.

Doubly heavy tetraquark bound and resonant states

We calculate the energy spectrum of the S-wave doubly heavy tetraquark systems, including the QQ(′)q¯q¯, QQ(′)s¯q¯, and QQ(′)s¯s¯ (Q(′)=b, c and q=u, d) systems within the constituent quark model. We use the complex scaling method to obtain bound states and resonant states simultaneously, and the Gaussian expansion method to solve the complex-scaled four-body Schrödinger equation. With a novel definition of the root-mean-square radii, we are able to distinguish between meson molecules and compact tetraquark states. The compact tetraquarks are further classified into three different types with distinct spatial configurations: compact even tetraquarks, compact diquark-antidiquark tetraquarks, and compact diquark-centered tetraquarks. In the I(JP)=0(1+) QQq¯q¯ system, there exists the D*D molecular bound state with a binding energy of −14 MeV, which is the candidate for Tcc(3875)+. The shallow B¯*B¯ molecular bound state is the bottom analog of Tcc(3875)+. Moreover, we identify two resonant states near the D*D* and B¯*B¯* thresholds. In the JP=1+ bbq¯q¯(I=0) and bbs¯q¯ systems, we obtain deeply bound states with a compact diquark-centered tetraquark configuration and a dominant χ3¯c⊗3c component, along with resonant states with similar configurations as their radial excitations. These states are the QCD analog of the helium atom. We also obtain some other bound states and resonant states with “QCD hydrogen molecule” configurations. Moreover, we investigate the heavy quark mass dependence of the I(JP)=0(1+) QQq¯q¯ bound states. We strongly urge the experimental search for the predicted states. Published by the American Physical Society 2024

Modeling the dynamics of contextual cueing effect by reinforcement learning.

Humans use environmental context for facilitating object searches. The benefit of context for visual search requires learning. Modeling the learning process of context for efficient processing is vital to understanding visual function in everyday environments. We proposed a model that accounts for the contextual cueing effect, which refers to the learning effect of scene context to identify the location of a target item. The model extracted the global feature of a scene and gradually strengthened the relationship between the global feature and its target location with repeated observations. We compared the model and human performance with two visual search experiments (letter arrangements on a gray background or a natural scene). The proposed model successfully simulated the faster reduction of the number of saccades required before target detection for the natural scene background compared with the uniform gray background. We further tested whether the model replicated the known characteristics of the contextual cueing effect in terms of local learning around the target, the effect of the ratio of repeated and novel stimuli, and the superiority of natural scenes.

SModelS v3: going beyond Z2 topologies

SModelS is a public tool for fast reinterpretation of LHC searches for new physics based on a large database of simplified model results. While previous versions were limited to models with a Z2-type symmetry, such as R-parity conserving supersymmetry, version 3 can now handle arbitrary signal topologies. To this end, the tool was fully restructured and now relies on a graph-based description of simplified model topologies. In this work, we present the main conceptual changes and novel features of SModelS v3, together with the inclusion of new experimental searches for resonant production of spin-1 and spin-0 mediators with decays to quarks or to dark matter. Applying these results to a model containing two mediators, we discuss the interplay of resonance and missing energy searches, and the model’s coverage by the currently available simplified model results.

Improved analysis of strong-interaction-stable doubly bottom tetraquarks on the lattice

We update earlier lattice results for the binding energies of the flavor antitriplet of strong-interaction-stable doubly bottom, JP=1+ tetraquarks, employing an extended sink construction which produces significantly improved ground-state effective-mass plateaus, as well as new, larger-volume ensembles which reduce possible finite-volume effects at lighter pion masses. The updated bindings are 115(17) MeV for the I=0 member of the antitriplet and 47(8) MeV for its I=1/2 partner. We also provide an update of our earlier study of the variable heavy mass dependence of binding in the 1+ channel and new results on this dependence for binding in the 0+ channel, accessible when the two heavy quarks have unequal masses. Implications of these results of potential relevance to experimental searches for signals of the production of doubly bottom tetraquarks and/or a possible bottom-charm partner of the Tcc are also discussed. Published by the American Physical Society 2024

Search for Pauli Exclusion Principle violations with Gator at LNGS

The Pauli Exclusion Principle (PEP) appears from fundamental symmetries in quantum field theories, but its physical origin is still to be understood. High-precision experimental searches for small PEP violations permit testing key assumptions of the Standard Model with high sensitivity. We report on a dedicated measurement with Gator, a low-background, high-purity germanium detector operated at the Laboratori Nazionali del Gran Sasso, aimed at testing PEP-violating atomic transitions in lead. The experimental technique, relying on forming a new symmetry state by introducing electrons into the pre-existing electron system through a direct current, satisfies the conditions of the Messiah-Greenberg superselection rule. No PEP violation has been observed, and an upper limit on the PEP violation probability of β2/2<4.8·10-29\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta ^2/2 < 4.8 \\cdot 10^{-29}$$\\end{document} (90% CL) is set. This improves the previous constraint from a comparable measurement by more than one order of magnitude.

High-dimensional Bayesian likelihood normalisation for CRESST's background model

Using CaWO4 crystals as cryogenic calorimeters, the CRESST experiment searches for nuclear recoils caused by the scattering of potential Dark Matter particles. A reliable identification of a potential signal crucially depends on an accurate background model. In this work, we introduce an improved normalisation method for CRESST's model of electromagnetic backgrounds, which is an important technical step towards developing a more accurate background model. Spectral templates based on Geant4 simulations are normalised via a Bayesian likelihood fit to experimental background data. Contrary to our previous work, no explicit assumption of partial secular equilibrium is required a priori, which results in a more robust and versatile applicability. This new method also naturally considers the correlation between all background components. Due to these purely technical improvements, the presented method has the potential to explain up to 82.7 % of the experimental background within [1 keV,40 keV], an improvement of at most 18.6 % compared to our previous method. The actual value is subject to ongoing validations of the included physics.

Solar neutrinos in cryogenic detectors

Coherent elastic neutrino-nucleus scattering (CEνNS) poses an irreducible background in the search for dark matter-nucleus elastic scatterings, which is commonly known as the neutrino floor. As direct dark matter search experiments keep improving their sensitivity into so far unexplored regions, they face the challenge of approaching this neutrino floor. A precise description of the CEνNS signal is therefore crucial for the description of backgrounds for future DM searches. In this work we discuss the scenario of detecting neutrinos in low-threshold, high-exposure cryogenic solid state experiments optimized for the search of low-mass dark matter. The energy range considered is completely dominated by solar neutrinos. In absence of any dark matter events, we treat solar neutrinos as the main signal of interest. We show that sensitivity to the flux of neutrinos from different production mechanisms can be achieved. In particular we investigate the sensitivity to the flux of pp and 7Be neutrinos, as well as CNO neutrinos. Furthermore, we investigate the sensitivity to dark matter signals in the presence of a solar neutrino background for different experimental scenarios, which are defined by three parameters: the target material, the energy threshold and the exposure. We show that experiments with thresholds of O(eV) and exposures of O(tonne-years), using CaWO4 or Al2O3 targets, have discovery potential for dark matter interaction cross sections in the neutrino floor.

Solving the problem of automating the learning process through experimental search for an individual educational trajectory

The automation of the educational process and the introduction of adaptive learning are becoming the most effective ways to solve the problem of the shortage of highly qualified personnel under digitalization of education.The article proposes an approach to the formation of individual educational trajectories as a composition of pedagogical experiments, which is characterized by good interpretability in comparison with methods based on machine learning. This approach, unlike most modern parametric solutions, involves an experimental search for an individual educational trajectory for each student of the group, and not just a part of the students of the group in which the application of a specific parametric solution is effective. It is proposed that the procedure of selecting educational technologies be automated similarly to how it is done by teachers in small groups, for example, by applying the automated trial and error method and its optimized versions. The possibility of transferring educational technologies to other courses is considered, without which technology reuse and scaling are impossible. A new function of the learning system is described, i. e. the formation of an individual educational trajectory, which is used throughout the study in higher education.The obtained results can be used in the construction of modern systems of individualization of learning and conducting distributed pedagogical experiments, which, in turn, reduces the threshold of teachers’ entry into the study of new learning technologies and accelerates the widespread dissemination of promising educational technologies.

Probing a light long-lived pseudo-scalar from Higgs decay via displaced taus at the LHC

A light (GeV mass) long-lived (cτ around dozens of millimeters) CP-odd scalar can be readily predicted in new physics models. In this work we investigate the Higgs decay into such a light scalar plus a Z-boson and take the aligned two-Higgs-doublet model (2HDM) as an example. This light long-lived scalar, with the dominant decay to tau leptons, will fly over a distance from the production point and present a displaced vertex in an Inner Detector of a generally purposed experiment like ATLAS or CMS. In our study we focus on the LHC experiment and perform Monte Carlo simulations for the signal and backgrounds. We demonstrate some benchmark points for the aligned 2HDM and find the signal to be detectable when the luminosity is accumulated to 300 fb−1. So our study suggests an experimental search for this process in the ongoing LHC.

Digital indicator for evaluating the hydraulic control system of the tractor gearbox

The effi ciency of using energy-saturated tractors in agriculture largely depends on the level of preparation for fi eld work, which in turn depends on an objective assessment of the general technical condition of components and assemblies to justify the repair and maintenance work carried out. Various diagnostic tools are widely used for a non-selective assessment of the general technical condition of the internal combustion engine: motor testers, crankcase gas fl ow meters, etc. However, there are no such means to assess the technical condition of the transmission (gearbox) of energy-saturated equipment of domestic production. In conditions of logistical remoteness from service centers, there is a need to develop digital indicators to assess the general technical condition of a hydraulically controlled gearbox according to the time of the transition process, allowing the end user to contact the dealer’s service company in a timely manner (The purpose of the study) to study the status of the issue, analyze the NTD and search experiments and develop an experimental digital indicator for monitoring the general technical condition of boxes transmission changes of energy-saturated tractors of domestic production according to the transition process in the hydraulic control system. (Materials and methods) Conducted an analysis, studied the NTD, as well as methodological guidelines for diagnosing and managing the reliability of agricultural machinery, previously produced control and diagnostic equipment, KI-112383 was chosen as an analog for the development of a digital indicator. It has been established that the method of transient characteristics is widely used to diagnose rapidly changing processes. Monitoring the time of the transition process in the hydraulic control system is a necessary diagnostic procedure that allows you to indiscriminately assess the overall technical condition of the KP of operated energysaturated tractors. (Results and discussion) the results of staged experiments using the E-14-140M ADC when running in the gearbox of the K-744R tractor on the stand showed the possibility of a comparative assessment of the general technical condition according to the transient characteristics of pressure recovery in the control system during gear shifting. To develop a prototype of the digital indicator, a virtual simulation was carried out with simulation of the algorithms of operation, and test tests were carried out on the developed laboratory installation. The developed experimental digital indicator can be used as an integrated monitoring tool to automatically determine the general technical condition of the gearbox, as well as inform the operator to minimize the infl uence of the «human» factor when changing gears. (Conclusions) For eff ective management of the general technical condition of tractors, it is necessary to pilot the implementation of the developed digital indicator, which will allow assessing the dynamics of changes in the transient pressure recovery process as a diagnostic parameter during the repair of the gearbox and under operating conditions of tractors without making changes to the design.

Theoretical Investigation of the Reaction of O(1D) with Formamide.

Carbamic acid (H2NCOOH) is a small organic molecule that is terrestrially unstable in condensed phases under ambient conditions but could survive in the low densities and temperatures of the interstellar medium. In this work, the reaction of formamide (H2NCOH) and electronically excited oxygen atoms in the 1D state, namely, O(1D), has been investigated computationally to determine the feasibility of carbamic acid production. Geometries for carbamic acid and other potential reaction products have been calculated, as well as all pertinent transition states. In addition, harmonic and anharmonic frequency calculations were performed to determine quartic and sextic centrifugal distortion constants for all products. This work enables spectroscopic predictions that can guide the experimental search for carbamic acid. Presented here are the calculations, geometries, molecular constants, and spectral predictions for possible products of the reaction between formamide and O(1D), as well as a discussion of which products are favored.

Research on similarity bias in dual objective visual search based on nuclear power human-machine interface icons

Using icons from nuclear power interface as the research object, this study explored how icon similarity affected the performance of dual objective visual search. Firstly, the process of generating similarity bias was described from the perspective of human cognitive processing. The feature attributes of nuclear power icons were extracted, and then associated and mapped with similarity bias attributes. Secondly, a total of 16 instruction icons, device icons, and component icons were selected to propose icon coding logic for different similarity dimensions, and similarity experimental materials were designed. Finally, a dual objective search experiment with a 4 × 4 matrix was conducted to explore the impact of graph similarity on search performance and to determine the priority of perceptual similarity, semantic similarity, and memory similarity. High-level (H) similarity between the two targets resulted in superior visual search performance (p = 0.01 between the response times of similarity high and medium/low). Improving experiential familiarity enhanced search performance in cases of low-level (L) (p = 0.021) and medium-level (M) (p ≤ 0.009) icon similarity, but had no significant impact on search performance in cases of high-level (H) similarity (p ≥ 0.269). Compared to semantic similarity, enhancing perceptual similarity was more likely to improve search performance(p = 0.024).

Examinations of search interactions, experiences and communication in collaborative search

PurposeThis study aims to explore the characteristics of collaborative information searching by comparing the differences in search experience and interaction between collaborative search mode and individual search mode and by analyzing the communication content and patterns during collaborative searches.Design/methodology/approachA user experiment was conducted using the Conference and Labs of the Evaluation Forum (CLEF)-Social Book Search platform, recruiting 16 individual and 18 collaborative participants. Each of the participants was required to complete two types of book search tasks in a lab setting. Interactions with the system were logged, and participants' experiences were captured through pre/post-search questionnaires. Additionally, the communication among collaborative participants was recorded and coded.FindingsThis study identified characteristics of collaborative information searching in three aspects. (1) Search experience: collaborative searchers showed a higher appreciation for the system’s functionality and aesthetics and were more engaged than individual searchers, despite experiencing slightly more mental strain. (2) Search strategies: in focus tasks, collaborative searchers made more decisions than individual searchers, indicating a need for book sorting. In open tasks, collaborative searchers take longer before making decisions, likely due to a higher level of interest and participation. (3) Communication content and pattern: collaborative searchers mainly discussed understanding and judgment of books and task plan. Searchers with same cognitive style talked more about search operations than those with different cognitive styles, while less about book judgment. Three communication patterns were identified: understanding-judgment, judgment-dominant and balanced. Judgment-dominant participants generally reported higher satisfaction with their search results than those in the other two patterns.Originality/valueThis study enhances understanding of collaborative search by comparing it with individual search and analyzing communication content, potentially inspiring collaborative search system and experiment design. Additionally, the coding table for communication between collaborative searchers offers valuable insights for future research.

First radial excitations of baryons in a contact interaction: Mass spectrum

We compute masses of twenty positive parity first radial excitations of spin-1/2 and spin-3/2 baryons composed of u, d, s, c, and b quarks in a quark-diquark picture within a contact interaction model. These excitations comprise of two elements; one characterized by a zero in the Faddeev amplitude, representing a radial excitation of the quark-diquark system and the other marked by a zero in the diquark’s Bethe-Salpeter amplitude, corresponding to an intrinsic excitation of the diquark correlation. Wherever possible, we compare our results with other models and/or experiment. We verify that the masses obtained through our model conform to the spacing rules for all the baryons studied, whether light or heavy and whether of spin-1/2 or spin-3/2. The computed masses do not just offer a guide to the future experimental searches but also compare well with the existing candidates for the possible radial excitations of some heavy baryons. Published by the American Physical Society 2024

Enhanced early galaxy formation in JWST from axion dark matter?

We demonstrate that enhanced early galaxy formation can generically arise in axion-like particle (ALP) dark matter (DM) models with a delayed onset of axion field oscillation. In these models, the formation of localized massive objects enhances structure formation, potentially addressing the excess recently observed by the James Webb Space Telescope (JWST), while remaining consistent with existing constraints. We identify viable parameter space with the ALP mass in the range of 10−22eV<ma<10−19eV. In addition, we show that the ALP parameter regions of interest can lead to intriguing complementary signatures in the small scale structure of DM halos and existing experimental searches for ALPs.