The Hunt for New Physics at the Large Hadron Collider Nath, Pran; Nelson, Brent; Davoudiasl, Hooman ...
Nuclear physics. Section B, Proceedings supplement,
03/2010, Letnik:
200
Journal Article, Conference Proceeding
Odprti dostop
The Large Hadron Collider presents an unprecedented opportunity to probe the realm of new physics in the TeV region and shed light on some of the core unresolved issues of particle physics. These ...include the nature of electroweak symmetry breaking, the origin of mass, the possible constituent of cold dark matter, new sources of CP violation needed to explain the baryon excess in the universe, the possible existence of extra gauge groups and extra matter, and importantly the path Nature chooses to resolve the hierarchy problem – is it supersymmetry or extra dimensions. Many models of new physics beyond the standard model contain a hidden sector which can be probed at the LHC. Additionally, the LHC will be a top factory and accurate measurements of the properties of the top and its rare decays will provide a window to new physics. Further, the LHC could shed light on the origin of neutralino masses if the new physics associated with their generation lies in the TeV region. Finally, the LHC is also a laboratory to test the hypothesis of TeV scale strings and D brane models. An overview of these possibilities is presented in the spirit that it will serve as a companion to the Technical Design Reports (TDRs) by the particle detector groups ATLAS and CMS to facilitate the test of the new theoretical ideas at the LHC. Which of these ideas stands the test of the LHC data will govern the course of particle physics in the subsequent decades.
Magnetic Resonance (MR) thermometry is used for the monitoring of MR-guided microwave ablations (MWA), and for the intraoperative evaluation of ablation regions. Nevertheless, the accuracy of ...temperature mapping may be compromised by electromagnetic interference emanating from the microwave (MW) generator. This study evaluated different setups for improving magnetic resonance imaging (MRI) during MWA with a modified MW generator.
MWA was performed in 15 gel phantoms comparing three setups: The MW generator was placed outside the MR scanner room, either connected to the MW applicator using a penetration panel with a radiofrequency (RF) filter and a 7 m coaxial cable (Setup 1), or through a waveguide using a 5 m coaxial cable (Setup 2). Setup 3 employed the MW generator within the MR scan room, connected by a 5 m coaxial cable. The coaxial cables in setups 2 and 3 were modified with custom shielding to reduce interference. The setups during ablation (active setup) were compared to a reference setup without the presence of the MW system. Thermometry and thermal dose maps (CEM43 model) were compared for the three configurations. Primary endpoints for assessment were signal-to-noise ratio (SNR), temperature precision, Sørensen-Dice-Coefficient (DSC), and RF-noise spectra.
Setup 3 showed highly significant electromagnetic interference during ablation with a SNR decrease by −60.4%±13.5% (p<0.001) compared to reference imaging. For setup 1 and setup 2 no significant decrease in SNR was measured with differences of −2.9%±9.8% (p=0.6) and −1.5%±12.8% (p=0.8), respectively. SNR differences were significant between active setups 1 and 3 with −51.2%±16.1% (p<0.001) and between active setups 2 and 3 with −59.0%±15.5% (p<0.001) but not significant between active setups 1 and 2 with 19.0%±13.7% (p=0.09). Furthermore, no significant differences were seen in temperature precision or DSCs between all setups, ranging from 0.33 °C ± 0.04 °C (Setup 1) to 0.38 °C ± 0.06 °C (Setup 3) (p=0.6) and from 87.0%±1.6% (Setup 3) to 88.1%±1.6% (Setup 2) (p=0.58), respectively.
Both setups (1 and 2) with the MW generator outside the MR scanner room were beneficial to reduce electromagnetic interference during MWA. Moreover, provided that a shielded cable is utilized in setups 2 and 3, all configurations displayed negligible differences in temperature precision and DSCs, indicating that the location of the MW generator does not significantly impact the accuracy of thermometry during MWA.
Integrating actuators into sensor networks is often considered to be the next logical step in the evolution of wireless sensor networks. However, few practical examples of such sensor and actuator ...networks have been demonstrated so far. In this paper, we present a prototype system that supports the easy prototyping of such applications in the area of home automation. We demonstrate the utility of this system with a simple light control application built on top of it. We also report first experiences and insights gained with the help of real-world experiments.
From June 1982 until December 1989, 93 permanent central venous catheters 59 external catheters (ECs) and 34 implanted catheters (ICs) were placed in 69 patients. The median age of these patients at ...placement was 5.6 years for ECs and 8.8 years for ICs (P less than 0.05). Follow-up evaluation was possible on 86 catheters (58 ECs and 28 ICs). The median time of insertion was 236 days and 316 days for ECs and ICs, respectively (P less than 0.05). The median number of open days was 58 for ECs and 66 for ICs (not significant). 17 catheters (6 ECs and 11 ICs) were transiently obstructed (P less than 0.005). 30 episodes of bacteraemia were documented in 20 patients. The incidence of catheter sepsis and bacteraemia of unknown source was one in 278 and 283 open days for ECs and ICs, respectively (not significant). In this retrospective study, ECs appeared to be as safe as ICs when infection was correlated with use of the catheter, but this finding should be confirmed in a randomised design.
This document proposes a collection of simplified models relevant to the design of new-physics searches at the LHC and the characterization of their results. Both ATLAS and CMS have already presented ...some results in terms of simplified models, and we encourage them to continue and expand this effort, which supplements both signature-based results and benchmark model interpretations. A simplified model is defined by an effective Lagrangian describing the interactions of a small number of new particles. Simplified models can equally well be described by a small number of masses and cross-sections. These parameters are directly related to collider physics observables, making simplified models a particularly effective framework for evaluating searches and a useful starting point for characterizing positive signals of new physics. This document serves as an official summary of the results from the "Topologies for Early LHC Searches" workshop, held at SLAC in September of 2010, the purpose of which was to develop a set of representative models that can be used to cover all relevant phase space in experimental searches. Particular emphasis is placed on searches relevant for the first ~50-500 pb-1 of data and those motivated by supersymmetric models. This note largely summarizes material posted at http://lhcnewphysics.org/, which includes simplified model definitions, Monte Carlo material, and supporting contacts within the theory community. We also comment on future developments that may be useful as more data is gathered and analyzed by the experiments.
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