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For most high-precision experiments in particle physics, it is essential to know the luminosity at highest accuracy. The luminosity is determined by the convolution of particle densities of the colliding beams. In special van der Meer transverse beam separation scans, the convolution function is sampled along the horizontal and vertical axes with the purpose of determining the beam convolution and getting an absolute luminosity calibration. For this purpose, the van der Meer data of luminometer rates are separately fitted in the two directions with analytic functions giving the best description. With the assumption that the 2D convolution shape is factorizable, one can calculate it from the two 1D fits. The task of XY factorization analyses is to check this assumption and give a quantitative measure of the effect of nonfactorizability on the calibration constant to improve the accuracy of luminosity measurements.

We perform a dedicated analysis to study XY nonfactorization on proton–proton data collected in 2022 at $\sqrt{s}=13.6$TeV by the CMS experiment [The CMS Collab., Luminosity measurement in proton-proton collisions at $\sqrt{s}=13.6$ TeV in 2022 at CMS (2024). A detailed examination of the shape of the bunch convolution function is presented, studying various biases, and choosing the best-fit analytic 2D functions to finally obtain the correction and its uncertainty.

We studied the dependence of morphology and luminosity of the SDSS galaxies on the environmental factors. The environmental factors considered include the local density due to the nearest neighbor galaxy ρ_n, morphology of the nearest neighbor, and the large-scale background density. We found the local environment set up by the nearest neighbor galaxy gives strong effects on the galaxy morphology. The probability for a galaxy to have an early morphological type critically depends on whether or not ρ_n is above the virialization density. We conclude that the well-known morphology-density relation is basically due to the interactions between galaxy pairs. Dependence of galaxy morphology on the large-scale density is found only because there is a statistical correlation between the average pair separation and the large-scale background density. We also found that galaxy luminosity depends on ρ_n, and that, when the large-scale density is fixed, more isolated galaxies are more likely to be recent merger products. We propose a scenario that a series of morphology and luminosity transformation occur through a series of distant/close interactions and mergers, which results in the morphology-luminosity-local density relation.

Construction of future Muon Collider (or dedicated $\mu$-ring) tangential to the energy frontier $hh$ colliders will give opportunity to realize $\mu p$ and $\mu A$ collisions at multi-TeV center-of-mass energies with sufficiently high luminosities. Obviously, such colliders will essentially enlarge the physics search potential of corresponding muon and hadron colliders for both the SM (especially for clarifying QCD basics and confinement hypothesis) and BSM phenomena. In addition, they will provide parton distribution functions for adequate interpretation of energy frontier $hh$ colliders’ and cosmic ray experiments data. This paper is devoted to review of main parameters of $\mu h$ colliders proposed until now.

To achieve the design luminosity of $1\times 10^{35}{\mathrm{\text{cm}}}^{-2}{\mathrm{\text{s}}}^{-1}$, the Super Tau-Charm Facility (STCF) adopts an extremely low ${\beta }_y^{\ast }$ and a crab waist (CW) collision design. The extremely small vertical beam size at the interaction point and low vertical emittance required to achieve a beam–beam parameter of around 0.1 make the CW colliders highly susceptible to beam instabilities arising from beam–beam interactions. Some of these instabilities need to be carefully assessed and optimized through strong–strong beam–beam simulations. In this paper, we investigate the luminosity stability of the STCF design parameters using both weak–strong and strong–strong simulations. We also explore the influence of the CW scheme and various beam parameters on luminosity. These findings offer valuable insight to guide lattice design and optimize global parameters for STCF.

In this paper, we utilize the effective Lagrangian method within the tree-level Born approximation to explore $\varphi$-meson photoproduction, i.e. $\gamma p\to \varphi p$. Our analysis encompasses contributions from various sources, including the Pomeron, $f_1$-Regge, pseudoscalar particles ($\pi$, $\eta$), scalar particles ($a_0$, $f_0$), protons, and three-nucleon resonance states. In addition, we consider a possible pentaquark-like $K^{\ast }\mathrm{\Sigma }$-bound state $P_s$. The findings indicate that, apart from the region near the threshold, contributions other than the Pomeron generally have a limited impact on the total cross-section. However, alternative contributions become crucial at specific angles, particularly at smaller values of $cos\theta$. The incorporation of $P_s$ and other nucleon resonances proves essential to elucidate the bump observed near $W\sim 2.15$GeV at very forward angles and behaviors within the range of $W=(2.0-2.3)$GeV. Furthermore, in the region with $W\ge 2.5$GeV, where nucleon resonances become negligible, contributions from the t-channel mesons become pivotal. Our calculations for spin density matrix components, examined in various frames, exhibit improvement when considering all contributions. This comprehensive approach successfully reproduces the observed bump by including $P_s$. We also briefly estimate the $P_s$ production via $\varphi$-meson photoproduction in the future Electron-Ion Collider (EIC), resulting in the luminosity of 10 fb${}^{-1}$ per month.

The use of gaseous plasmas to strongly focus high density, high energy electron and positron beams has been experimentally demonstrated. Focusing plasmas have been beam-induced. In addition, interesting aspects of laser-induced preionization of the target gas have been observed. Potential applications to luminosity enhancement for linear colliders warrant further development of these techniques with machine parameters in mind.

Previously, the generalized luminosity ℒ was defined and calculated for all incident channels based on an NLC e⁺ e^- design. Alternatives were then considered to improve the differing beam-beam effects in the e^- e^-, eγ and γγ channels. One example was tensor beams composed of bunchlets n_ijk implemented with a laser-driven, silicon accelerator based on micromachining techniques. Problems were considered and expressions given for radiative broadening due to bunchlet manipulation near the final focus to optimize luminosity via charge enhancement, neutralization or bunch shaping. Because the results were promising, we explore fully integrated structures that include sources, optics (for both light and particles) and acceleration in a common format - an accelerator-on-chip. Acceptable materials (and wavelengths) must allow velocity synchronism between many laser and electron pulses with optimal efficiency in high radiation environments. There are obvious control and cost advantages that accrue from using silicon structures if radiation effects can be made acceptable and the structures fabricated. Tests related to deep etching, fabrication and radiation effects on candidate amorphous and crystalline materials show Si(λ_L > 1.2μm) and fused SiO₂(λ_L > 0.3μm) to be ideal materials.

Previously, the generalized luminosity was defined and calculated for all incident channels based on an NLC e⁺e^- design. Alternatives were then considered to improve the differing beam-beam effects in the e^-e^-, eγ and γγ channels. Regardless of the channel, there was a large flux of outgoing, high energy photons that were produced from the beam-beam interaction e.g. beamstrahlung that needs to be disposed of and whose flux depended on . One approach to this problem is to consider it a resource and attempt to take advantage of it by disposing of these straight–ahead photons in more useful ways than simply dumping them. While there are many options for monitoring the luminosity, any method that allows feedback and optimization in real time and in a non-intercepting and non-interfering way during normal data taking is extremely important – especially if it provides other capabilities such as high resolution tuning of spot sizes and can be used for all incident channels without essential modifications to their setup. Our "pin-hole" camera appears to be such a device if it can be made to work with high energy photons in ways that are compatible with the many other constraints and demands on space around the interaction region. The basis for using this method is that it has, in principle, the inherent resolution and bandwidth to monitor the very small spot sizes and their stabilities that are required for very high, integrated luminosity. While there are many possible, simultaneous uses of these outgoing photon beams, we limit our discussion to a single, blind, proof-of-principle experiment that was done on the FFTB line at SLAC to certify the concept of a camera obscura for high energy photons.

In this paper, we analyze scenario with strongly interacting massive particles which follows from the Standard Model extension with singlet quark. The lightest new neutral hadron is stable, it can be interpreted as a candidate for hadronic dark matter. Here, we consider principal features of this scenario: large mass of new hadrons, fine and hyperfine splitting in the spectrum of hadron states, low-energy interaction with the standard particles. Both splitting effects lead to processes which can be registered in cosmic rays and deciphered as the hadronic dark matter manifestations. In this work, we reconsider and specify some results from our previous papers.

This article describes the fundamental limitations on the performance of electron–positron circular colliders. After introducing the subject from its end use parameter, the luminosity, we discuss in detail the various accelerator physics limitations and the evolution of several ingenious frontier ideas to ever increase the luminosity of these colliders.

The physics motivation, accelerator science, plans for future facilities and major accelerator systems of electron–ion colliders are presented. The science enabled by these machines motivates the machine design with high luminosity and flexibility, and thus leads to new challenges in accelerator science. Innovative solutions, developed in order to achieve the objectives set for these machines, are described. Major accelerator systems and accelerator physics issues are also described, and references are provided for readers interested in greater detail.

I review some accelerator physics topics for circular as well as linear colliders, considering both lepton and hadron beams.

For several decades already, particle colliders have been essential tools for particle physics. From the very beginning, such accelerators have been among the most complicated scientific instruments ever built, including a number of innovative technological developments. Examples are ultrahigh vacuum systems, magnets with a very high magnetic field, and equipment for sub-ns synchronization and sub-mm precision alignment of equipment inside multi-km underground tunnels. Some key technologies are related to the focusing of the beam down to a scale of sub-μm at the collision point to obtain high luminosity. This review provides an overview of collision concepts and technologies for circular particle colliders, starting from the first ideas. In particular, it discusses such novel schemes and related technologies as crab waist collision and round beam collision.

Particle acceleration in plasma creates a possibility of exceptionally high accelerating gradients and appears to be a very attractive option for future linear electron–positron and/or $\gamma$–$\gamma$ colliders. These high accelerating gradients have already been demonstrated in a number of experiments. However, a linear collider requires exceptionally high beam brightness which still needs to be demonstrated. In this article we discuss major phenomena which limit the beam brightness of accelerated beam and, consequently, the collider luminosity.

We report preliminary results on the measurement of the cross section of the process e⁺e^- → K⁺K^-π⁺π^- in the c.m. energy range from 1.5 GeV to 2 GeV. It is shown that the cross section is dominated by the contributions of several intermediate states K⁺K^-ρ, K*Kπ, ϕπ⁺π^- and K*K*.

The following sections are included:

• Prelude
• Single Particle Acceleration and Focusing Limits in Structures: Laser-driven Plasma Wakefields, Structured Nanomaterials and Crystals
• Quantum Sensors of the “Dark” Universe and Weak Processes
• Outlook
• Acknowledgments
• References

We report on a high-precision calculation of the Bhabha process in QED, of interest for precise luminosity determination of low-energy electron-positron colliders. The calculation is based on the matching of exact next-to-leading order corrections with a Parton Shower algorithm. The structure of the algorithm (implemented in an improved version of the event generator BABAYAGA) is illustrated, with a discussion on the resulting theoretical uncertainty, of the order of 0.1%.

The CMS HF Calorimeter was the first detector to be lowered into the cavern at UX5. It was placed in the garage position during the lowering of the rest of the big CMS pieces. The commissioning of the hardware parts is continuing, especially integrating the HF and completing the monitoring systems, such as, online laser, LED and radioactive source monitoring. Also a special monitor system for the radiation damage (raddam) of the quartz fibers is being implemented. Calibration measurements of the calorimeter had already started even before the lowering. Progress in the calibration work and current plans for the HF calorimeter during the low luminosity run will be summarized.

LUCID (LUminosity measurement using Cherenkov Integrating Detector) is a Cherenkov counter designed to monitor the luminosity in the ATLAS experiment. Since the final accuracy of the measurement of some crucial physical quantities in the LHC program will depend on the precision of the luminosity measurement, it is mandatory to push the latter to its best. This in turn implies the need to monitor the beam conditions. In this paper an overview of LUCID is given. After a description of the detector, an insight into the luminosity measurement strategy in ATLAS is given, as well as a description of the calibration strategy of LUCID.