Institute for High Energy Physics

Environmental factors, such as temperature-induced drift of devices or objects under test, adversely affect measurement accuracy. To address the suppression of low-frequency disturbing in long-range surface profiler measurements, traditional forward-backward sequential scanning partially mitigates drift, since this method’s drift error suppression relies on the principle of measurement averaging, it demonstrates limited suppression effectiveness against nonlinear low-frequency drift and suffers from low measurement efficiency. Inspired by the mechanism of LIA in weak signal detection-where signals outside the reference frequency are doubled in frequency through correlation detection and subsequently suppressed by LPF, we propose shifting the suppression strategy from simple mean-value cancellation to altering the frequency-domain characteristics of drift. This approach transforms low-frequency drift into higher-frequency components that can be effectively filtered, rather than merely attempting to average out the drift effects. suffers from low measurement efficiency. Two measurement strategies—random sampling and optimized forward-backward downsampled path scanning—are designed, combined with low-pass filtering to separate drift disturbing from the true surface profile. Multi-objective optimization analyzed the relationship between sampling stepping scales and measurement accuracy/efficiency in the LTP system, determining the optimal sampling step to balance precision and efficiency. Simulations show that for linear errors, both traditional forward and backward scanning and path-optimized scanning can suppress them to near-zero levels, while random scanning fails. For nonlinear errors, path-optimized scanning outperforms both random and traditional forward and backward scanning with nearly halved time costs. Experimental validation on a 50 mm standard flat crystal demonstrates that the optimized downsampled path scanning controls drift errors at 18 nrad RMS while reducing single-measurement cycles by 48.4% compared to forward-backward sequential scanning. This method effectively relaxes environmental control requirements (enhancing system robustness. The measurement process can directly proceed without undergoing the conventional procedure of closing the isolation enclosure and waiting for environmental stabilization. ) and provides what we believe to be a new solution for high-precision optical surface metrology.

The thiamine (vitamin B1) biosynthesis pathway is essential for most prokaryotes and some eukaryotes, including yeasts and plants. The 4-amino-5-hydroxymethyl-2-methylpyrimidine phosphate kinase (HMPP kinase), encoded by the thiD gene, catalyzes two phosphorylation reactions involving intermediates in this pathway, ultimately producing thiamine pyrophosphate, the active form of thiamine. Here, we present the crystal structure of HMPP kinase from Thermus thermophilus HB8 (TtHMPPK), resolved at a resolution of 2.05 Å. The asymmetric unit of the TtHMPPK structure includes one protomer, though it functions as a homodimer in its active form, like the HMPP kinase from Salmonella typhimurium. The TtHMPPK protomer is an α/β protein featuring nine β-sheets flanked by eight structurally conserved α-helices, which are characteristic of the ribokinase family. The structure reveals a Rossmann β–α–β motif, commonly found in nucleotide-binding proteins. Structural analysis of TtHMPPK, compared to the Salmonella typhimurium HMPP kinase, indicates that Ala16, Thr40, Gln42, Ala78, and Val105 are active site residues involved in catalysis. The structural studies suggest that TtHMPPK belongs to the ribokinase superfamily and exhibits structural similarities with an enzyme containing a Rossmann-like structural motif (RLM). This Rossmann fold enables HMPP kinase to catalyze the phosphorylation of HMPP, a critical step in thiamine production.

A bstract We elaborate on the partially massless spin 5/2 supermultiplet, which contains partially massless spin 5/2, massless and partially massless spin 2, as well as massless spin 3/2. We consider the global supertransformations connecting partially massless spin 5/2 to its two possible superpartners, massless and partially massless spin 2, and make them local by switching the interaction with the massless gravitino. We use a frame-like gauge-invariant formalism to describe free fields and the Fradkin-Vasiliev formalism to construct interactions, Due to the presence of the Stueckelberg fields in the gauge-invariant description of massive and partially massless fields, we face ambiguities related to field redefinitions. We use this freedom to simplify calculations. At the same time, we demonstrate how these ambiguities can be resolved using unfolded equations.

The opening of the gravitational wave window has significantly enhanced our capacity to explore the Universe’s most extreme and dynamic sector. In the mHz frequency range, a diverse range of compact objects, from the most massive black holes at the farthest reaches of the Universe to the lightest white dwarfs in our cosmic backyard, generate a complex and dynamic symphony of gravitational wave signals. Once recorded by gravitational wave detectors, these unique fingerprints have the potential to decipher the birth and growth of cosmic structures over a wide range of scales, from stellar binaries and stellar clusters to galaxies and large-scale structures. The TianQin space-borne gravitational wave mission is scheduled for launch in the 2030s, with an operational lifespan of five years. It will facilitate pivotal insights into the history of our Universe. This document presents a concise overview of the detectable sources of TianQin, outlining their characteristics, the challenges they present, and the expected impact of the TianQin observatory on our understanding of them.

The discovery of the Higgs boson at CERN’s Large Hadron Collider (LHC) completed the Standard Model (SM), yet evidence for physics beyond the SM remains crucial. Intriguingly, LHC Run 1 (2010–2012) data showed an excess in muon-electron invariant mass around $150\pm5$ GeV, hinting at a new Higgs-like scalar boson (S). Additional anomalies—such as multilepton events, moderate missing energy, and potential bottom quark jets—also show deviations from SM expectations. These signatures are explained by a simplified model featuring a heavier Higgs boson (H) decaying into two lighter scalars (S), where S decays into W bosons, b-quarks, or invisibly. Using this model, we identify narrow excesses in di-photon and Z-photon channels near 152 GeV. Incorporating the latest di-photon plus lepton data, we find a combined global significance of $5.4\sigma$—the strongest signal to date for a narrow resonance consistent with beyond the SM (BSM) physics in proton-proton collisions at the LHC. If confirmed, this new resonance could signal the start of a BSM epoch in particle physics, offering insights into unresolved mysteries such as dark matter, electroweak symmetry breaking, and the origin of mass beyond the current theoretical framework.

This erratum includes correction of misprints in the expressions for $\beta$ β functions, as well as remarks clarifying the notation. Numerical results of the article are not affected.

A bstract The very existence of partially massless spin 2 supermultiplet tell us that partially massless spin 2 has two natural super-partners: massless spin 3/2 and massive spin 3/2 with some special value of mass. As for any pair of fields connected by global supertransformations there are two natural questions: existence of the self-interaction and possibility to make supertransformations to be local by switching their interaction with massless spin 3/2 gravitino. At first, we consider a self-interaction for the partially massless spin 2 and massive spin 3/2 which may be considered as the first approximation to partially massless supergravity and provide a direct construction of the minimal (i.e. having no more than one derivative) vertex which resembles usual supergravity. Then we consider localization of global supersymmetry which connects partially massless spin 2 with its two possible super-partners — massless spin 3/2 and massive with special mass value. For the first case we also managed to construct a minimal vertex having no more that one derivative. Again this vertex can be considered as a part of what can be called partially massless N = 2 supergravity. As for the second case, the corresponding vertex does exist but it has higher derivative terms.

Atomically dispersed catalysts have attracted significant attention for their high efficiency and excellent catalytic performance in electrocatalytic reactions. While numerous studies have demonstrated that altering the coordination environment of metal atoms can boost catalytic performance, the profound impact that even minor structural modifications at the catalytic active center can have on electrocatalytic activity remains largely unexplored. Here, two Pt‐Cu diatomic catalysts—Pt‐Cu/Nenriched and Cu‐Pt/Nenriched—featuring subtle differences are developed in metal coordination structures that are challenging to detect using conventional characterization methods. Operando X‐ray absorption spectroscopy and electrocatalytic tests on sulfur redox reaction revealed a significant gap between reactant adsorption–desorption process and catalytic activity. These differences are attributed to minor variations in the number of nitrogen atoms coordinating with the metal atom. This study highlights how small coordination changes in atomically dispersed metal catalysts can greatly impact electrocatalytic performance, offering insights into the rational design of atomically dispersed catalysts in electrochemical reactions.

Computed Tomography (CT) has been widely adopted in medicine and it is increasingly being used in scientific and industrial applications. Parallelly, research in different mathematical areas concerning discrete inverse problems has led to the development of new sophisticated numerical solvers that can be applied in the context of CT. The Tomographic Iterative GPU-based Reconstruction (TIGRE) toolbox was born almost a decade ago precisely in the gap between mathematics and high performance computing for real CT data, providing user-friendly open-source software tools for image reconstruction. However, since its inception, the tools’ features and codebase have had over a twenty-fold increase, and are now including greater geometric flexibility, a variety of modern algorithms for image reconstruction, high-performance computing features and support for other CT modalities, like proton CT. The purpose of this work is two-fold: first, it provides a structured overview of the current version of the TIGRE toolbox, providing appropriate descriptions and references, and serving as a comprehensive and peer-reviewed guide for the user; second, it is an opportunity to illustrate the performance of several of the available solvers showcasing real CT acquisitions, which are typically not be openly available to algorithm developers.

Laser trackers or total stations are most widely used in particle accelerator measurement with high measurement accuracy but low efficiency. Close range photogrammetry has great characteristics of both high accuracy and efficiency, other than that, it enables non-contact observation, which is ideal for high-radiation accelerator measurement environments. In order to obtain the absolute position of the measurement area using close range photogrammetry, the position and orientation of the camera and the scale of the photo must be accurately determined at the moment of observation. A new three-dimensional visual measurement equipment is developed in this paper, which can obtain image, distance, and angle data at the same time. Unified adjustment of all three types of observations can more accurately determine position, orientation and scale datum. We used simulated data for experimental validation, comparing the new algorithm with another two algorithms: the traditional fixed point constraint and centroid datum constraint. The experiment results show that it can significantly improve positioning accuracy by adding distance and angle observations. The three-dimensional coordinate accuracy can reach up to 0.073 mm, while the accuracy of the other two algorithms can only be achieved 0.137 and 0.153 mm, the improvement is approximately 52.4%. Especially in the forward direction of the tunnel, the positioning accuracy is significantly improved, with an improvement of about 67.8 %.

Superconducting undulators (SCUs) are increasingly vital for synchrotron light sources and free-electron lasers in modern particle accelerators due to their ability to surpass the performance limitations of traditional permanent magnet undulators (PMUs). This paper delves into the theoretical framework and key technologies of SCUs, substantiating findings with experimental verifications. The theoretical analysis and numerical simulations of SCU magnetic fields are conducted based on Maxwell’s equations, leading to optimized magnetic field distributions. Advanced manufacturing processes, such as high-precision coil winding and epoxy resin impregnation, are developed and refined. The paper also details the SCU’s cryogenic, power supply, quench protection, vacuum, and magnetic field measurement systems, ensuring safe and stable operations in real-world conditions. Prototypes, including 1.5-meter-long SCUs, undergo rigorous tests at liquid helium temperatures to validate reliability, revealing that while the SCU meets the design goals in both the vertical and horizontal states, gravity effects in the horizontal state deteriorate the quality of the magnetic field and require iterative optimization. The improvement of the magnetic field quality is achieved by locally adjusting the tuning gap and the end correction coils. Despite the advances that have been made, it is essential to further enhance the performance of SCUs by optimizing the end design and adding means to regulate the magnetic field at low temperatures. This study lays a solid theoretical and technical foundation for the application of SCUs in advanced light sources, and is expected to provide a meaningful reference for the development of more SCUs in the future.