7,325 research outputs found

    Further investigation of dilepton-based center-of-mass energy measurements at e+^{+}e−^{-} colliders

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    Methods for measuring the absolute center-of-mass energy using dileptons from e+^{+}e−^{-} collision events are further developed with an emphasis on accelerator, detector, and physics limitations. We discuss two main estimators, the lepton momentum-based center-of-mass energy estimator, sp\sqrt{s}_{p}, discussed previously, and new estimators for the electron and positron colliding beam energies, denoted E−CE^{\text{C}}_{-} and E+CE^{\text{C}}_{+}. In this work we focus on the underlying limitations from beam energy spread, detector resolution, and the modeling of higher-order QED radiative corrections associated with photon emissions originating from initial-state-radiation (ISR), final-state-radiation (FSR), and their interference. We study the consequent implications for the potential of these methods at center-of-mass energies ranging from 90 GeV to 1 TeV relevant to a number of potential accelerator realizations in the context of measurements of masses of the Z, W, H, top quark, and new particles. The statistical importance of the Bhabha channel for Higgs factories is noted. Additional extensive work on improving the modeling of the luminosity spectrum including the use of copulas is also reported.Comment: 22 pages, 10 figures, LCWS 2023 Proceeding

    Situating Neogeography

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    Center-of-mass energy determination using e+e−e^+e^- to μ+μ−\mu^+\mu^- (γ)(\gamma) events at future e+e−e^+e^- colliders

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    Methods for measuring the absolute center-of-mass energy, s\sqrt{s}, and its distribution, are investigated for future e+e−e^+e^- Higgs-factory colliders using in situ e+e−e^+e^- collisions. We emphasize the potential of an estimator based on the measurement of muon momenta that we denote sp\sqrt{s}_p. It can be determined with high precision in e+e−e^+e^- to μ+μ−\mu^+\mu^-(γ\gamma) events while being sensitive to effects from beam energy spread, beamstrahlung, initial-state radiation (ISR), final-state radiation (FSR), crossing angle, and detector resolution. The measurement precision is enabled by a high-precision low-mass tracker; the reported performance estimates are based on full simulation of the tracker response of the ILD detector concept for the ILC operating at s=250\sqrt{s} = 250 GeV. The underlying statistical precision is 1.9 ppm for a 2.0 ab−1^{-1} dataset at ILC. The ultimate utility will depend largely on how well one can calibrate and maintain the tracker momentum scale.Comment: 30 pages; Submitted to the Proceedings of the US Community Study on the Future of Particle Physics (Snowmass 2021). v3 correct scaling formula in footnote 1 and add corresponding referenc

    Radio Astronomy

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    Contains reports on four research projects.National Aeronautics and Space Administration (Grant NsG-240-62)National Aeronautics and Space Administration (Grant NsG-419)Lincoln Laboratory (Purchase Order DDL BB-107)U. S. Air Force (Contract AF 19(628)-500)Office of Naval Research (Contract Nonr 3963(02

    Emergency supply of prescription-only medicines to patients by community pharmacists: a mixed methods evaluation incorporating patient, pharmacist and GP perspectives

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    Objective To evaluate and inform emergency supply of prescription-only medicines by community pharmacists (CPs), including how the service could form an integral component of established healthcare provision to maximise adherence. Design Mixed methods. 4 phases: prospective audit of emergency supply requests for prescribed medicines (October–November 2012 and April 2013); interviews with CPs (February–April 2013); follow-up interviews with patients (April–May 2013); interactive feedback sessions with general practice teams (October–November 2013). Setting 22 community pharmacies and 6 general practices in Northwest England. Participants 27 CPs with experience of dealing with requests for emergency supplies; 25 patients who received an emergency supply of a prescribed medicine; 58 staff at 6 general practices. Results Clinical audit in 22 pharmacies over two 4-week periods reported that 526 medicines were requested by 450 patients. Requests peaked over a bank holiday and around weekends. A significant number of supplies were made during practice opening hours. Most requests were for older patients and for medicines used in long-term conditions. Difficulty in renewing repeat medication (forgetting to order, or prescription delays) was the major reason for requests. The majority of medicines were ‘loaned’ in advance of a National Health Service (NHS) prescription. Interviews with CPs and patients indicated that continuous supply had a positive impact on medicines adherence, removing the need to access urgent care. General practice staff were surprised and concerned by the extent of emergency supply episodes. Conclusions CPs regularly provide emergency supplies to patients who run out of their repeat medication, including during practice opening hours. This may aid adherence. There is currently no feedback loop, however, to general practice. Patient care and interprofessional communication may be better served by the introduction of a formally structured and funded NHS emergency supply service from community pharmacies, with ongoing optimisation of repeat prescribing

    Populating the galaxy velocity dispersion - supermassive black hole mass diagram: A catalogue of (M_bh, sigma) values

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    An updated catalogue of 76 galaxies with direct supermassive black hole mass measurements (M_bh) plus, when available, their host bulge's central velocity dispersion (sigma_0) is provided. Fifty of these mass measurements are considered reliable, while the others remain somewhat uncertain at this time. An additional eight stellar systems, including one stellar cluster and three globular clusters, are listed as hosting potential intermediate mass black holes < 10^6 M_solar. With this larger data set, the demographics within the M_bh-sigma_0 diagram are briefly explored. Many barred galaxies are shown to be offset from the M_bh-sigma_0 relation defined by the non-barred galaxies, in the sense that their velocity dispersions are too high. Furthermore, including 88 AGN with black hole mass estimates from reverberation mapping studies, we speculate that barred AGN may follow this same general trend. We also show that some AGN with sigma_0 < 100 km/s tend to reside up to 0.6 dex above the "barless" M_bh-sigma_0 relation. Finally, it is shown that ``core galaxies'' appear not to define an additional subdivision of the M_bh-sigma_0 diagram, although improved methods for measuring sigma_0-values will be valuable.Comment: To appear in PASA, accepted on the 4th of July, 200

    Seasonal total methane depletion in limestone caves

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    Methane concentration in caves is commonly much lower than the external atmosphere, yet the cave CH4 depletion causal mechanism is contested and dynamic links to external diurnal and seasonal temperature cycles unknown. Here, we report a continuous 3-year record of cave methane and other trace gases in Jenolan Caves, Australia which shows a seasonal cycle of extreme CH4 depletion, from ambient ∼1,775 ppb to near zero during summer and to ∼800 ppb in winter. Methanotrophic bacteria, some newly-discovered, rapidly consume methane on cave surfaces and in external karst soils with lifetimes in the cave of a few hours. Extreme bacterial selection due to the absence of alternate carbon sources for growth in the cave environment has resulted in an extremely high proportion 2-12% of methanotrophs in the total bacteria present. Unexpected seasonal bias in our cave CH4 depletion record is explained by a three-step process involving methanotrophy in aerobic karst soil above the cave, summer transport of soil-gas into the cave through epikarst, followed by further cave CH4 depletion. Disentangling cause and effect of cave gas variations by tracing sources and sinks has identified seasonal speleothem growth bias, with implied palaeo-climate record bias
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