121,327 research outputs found
Weighing wimps with kinks at colliders: invisible particle mass measurements from endpoints
We consider the application of endpoint techniques to the problem of mass
determination for new particles produced at a hadron collider, where these
particles decay to an invisible particle of unknown mass and one or more
visible particles of known mass. We also consider decays of these types for
pair-produced particles and in each case consider situations both with and
without initial state radiation. We prove that, in most (but not all) cases,
the endpoint of an appropriate transverse mass observable, considered as a
function of the unknown mass of the invisible particle, has a kink at the true
value of the invisible particle mass. The co-ordinates of the kink yield the
masses of the decaying particle and the invisible particle. We discuss the
prospects for implementing this method at the LHC
Recommended from our members
Concentrator cell methodology in the regeneration and recycle of chromium etching solutions using membrane technology
The regeneration of chromium (VI) and the recovery of etched copper from chromium etching solutions by electrodialysis is improved by the addition of a concentrator cell, using ion exchange resins or activated carbon cloth as concentrator media, in the catholyte chamber. The maximum percentages for the regeneration of chromium and recovery of copper in these systems is however less than 80 and 90% respectively because of the competition between the processes of oxidation of Cr(III) and electrodeposition of copper. A novel combination of electrolysis with electrodialysis and concentrator cell technology is developed that achieves 92.1% chromium regeneration and 90.4% copper recovery.EPSRC/DTI through the Link WMR03 programme and to Fluid Dynamics International Ltd. for financial support
Transverse masses and kinematic constraints: from the boundary to the crease
We re-examine the kinematic variable m_T2 and its relatives in the light of
recent work by Cheng and Han. Their proof that m_T2 admits an equivalent, but
implicit, definition as the `boundary of the region of parent and daughter
masses that is kinematically consistent with the event hypothesis' is
far-reaching in its consequences. We generalize their result both to simpler
cases (m_T, the transverse mass) and to more complex cases (m_TGen). We further
note that it is possible to re-cast many existing and unpleasant proofs (e.g.
those relating to the existence or properties of "kink" and "crease" structures
in m_T2) into almost trivial forms by using the alternative definition. Not
only does this allow us to gain better understanding of those existing results,
but it also allows us to write down new (and more or less explicit) definitions
of (a) the variable that naturally generalizes m_T2 to the case in which the
parent or daughter particles are not identical, and (b) the inverses of m_T and
m_T2 -- which may be useful if daughter masses are known and bounds on parent
masses are required. We note the implications that these results may have for
future matrix-element likelihood techniques
Burglary project
This report outlines the process and findings from an innovative project for students. This work was part of the curriculum and involved students working with West Yorkshire Police as part of the safer Leeds project in designing and making a film for students n crime prevention and personal safety in Leed
Impact of use of optical surface imaging on initial patient setup for stereotactic body radiotherapy treatments
Purpose
To evaluate the effectiveness of surface image guidance (SG) for preāimaging setup of stereotactic body radiotherapy (SBRT) patients, and to investigate the impact of SG reference surface selection on this process.
Methods and materials
284 SBRT fractions (SGāSBRT = 113, nonāSGāSBRT = 171) were retrospectively evaluated. Differences between initial (preāimaging) and treatment couch positions were extracted from the recordāandāverify system and compared for the two groups. Rotational setup discrepancies were also computed. The utility of orthogonal kVs in reducing CBCT shifts in the SGāSBRT/nonāSGāSBRT groups was also calculated. Additionally, the number of CBCTs acquired for setup was recorded and the average for each cohort was compared. These data served to evaluate the effectiveness of surface imaging in preāimaging patient positioning and its potential impact on the necessity of including orthogonal kVs for setup. Since reference surface selection can affect SG setup, daily surface reproducibility was estimated by comparing cameraāacquired surface references (VRT surface) at each fraction to the external surface of the planning CT (DICOM surface) and to the VRT surface from the previous fraction.
Results
The reduction in all initialātoātreatment translation/rotation differences when using SGāSBRT was statistically significant (RankāSum test, Ī± = 0.05). Orthogonal kV imaging kept CBCT shifts below reimaging thresholds in 19%/51% of fractions for SGāSBRT/nonāSGāSBRT cohorts. Differences in average number of CBCTs acquired were not statistically significant. The reference surface study found no statistically significant differences between the use of DICOM or VRT surfaces.
Conclusions
SGāSBRT improved preāimaging treatment setup compared to ināroom laser localization alone. It decreased the necessity of orthogonal kV imaging prior to CBCT but did not affect the average number of CBCTs acquired for setup. The selection of reference surface did not have a significant impact on initial patient positioning
Recommended from our members
Room reflections and constancy in speech-like sounds: within-band effects
The experiment asks whether constancy in hearing precedes or follows grouping. Listeners heard speech-like
sounds comprising 8 auditory-filter shaped noise-bands that had temporal envelopes corresponding to those
arising in these filters when a speech message is played. The ācontextā words in the message were ānext youāll
get _to click onā, into which a āsirā or āstirā test word was inserted. These test words were from an 11-step
continuum that was formed by amplitude modulation. Listeners identified the test words appropriately and quite
consistently, even though they had the āroboticā quality typical of this type of 8-band speech. The speech-like
effects of these sounds appears to be a consequence of auditory grouping. Constancy was assessed by comparing
the influence of room reflections on the test word across conditions where the context had either the same level
of reflections, or where it had a much lower level. Constancy effects were obtained with these 8-band sounds,
but only in āmatchedā conditions, where the room reflections were in the same bands in both the context and the
test word. This was not the case in a comparison āmismatchedā condition, and here, no constancy effects were
found. It would appear that this type of constancy in hearing precedes the across-channel grouping whose
effects are so apparent in these sounds. This result is discussed in terms of the ubiquity of grouping across
different levels of representation
Professional judgement and decision-making in social work
This is an Accepted Manuscript of an article published by Taylor & Francis Group in Journal of Social Work Practice on 3/04/2018, available online: http://www.tandfonline.com/10.1080/02650533.2018.1462780
Editorial for a special issue on Professional Judgement and Decision Making in Social Wor
- ā¦