2,845 research outputs found
A Fast Track towards the `Higgs' Spin and Parity
The LHC experiments ATLAS and CMS have discovered a new boson that resembles
the long-sought Higgs boson: it cannot have spin one, and has couplings to
other particles that increase with their masses, but the spin and parity remain
to be determined. We show here that the `Higgs' + gauge boson invariant-mass
distribution in `Higgs'-strahlung events at the Tevatron or the LHC would be
very different under the J^P = 0+, 0- and 2+ hypotheses, and could provide a
fast-track indicator of the `Higgs' spin and parity. Our analysis is based on
simulations of the experimental event selections and cuts using PYTHIA and
Delphes, and incorporates statistical samples of `toy' experiments.Comment: 18 pages, 9 pdf figure
Measurements of the Production, Decay and Properties of the Top Quark: A Review
With the full Tevatron Run II and early LHC data samples, the opportunity for
furthering our understanding of the properties of the top quark has never been
more promising. Although the current knowledge of the top quark comes largely
from Tevatron measurements, the experiments at the LHC are poised to probe
top-quark production and decay in unprecedented regimes. Although no current
top quark measurements conclusively contradict predictions from the standard
model, the precision of most measurements remains statistically limited.
Additionally, some measurements, most notably the forward-backward asymmetry in
top quark pair production, show tantalizing hints of beyond-the-Standard-Model
dynamics. The top quark sample is growing rapidly at the LHC, with initial
results now public. This review examines the current status of top quark
measurements in the particular light of searching for evidence of new physics,
either through direct searches for beyond the standard model phenomena or
indirectly via precise measurements of standard model top quark properties
Prompt Decays of General Neutralino NLSPs at the Tevatron
Recent theoretical developments have shown that gauge mediation has a much
larger parameter space of possible spectra and mixings than previously
considered. Motivated by this, we explore the collider phenomenology of gauge
mediation models where a general neutralino is the lightest MSSM superpartner
(the NLSP), focusing on the potential reach from existing and future Tevatron
searches. Promptly decaying general neutralino NLSPs can give rise to final
states involving missing energy plus photons, Zs, Ws and/or Higgses. We survey
the final states and determine those where the Tevatron should have the most
sensitivity. We then estimate the reach of existing Tevatron searches in these
final states and discuss new searches (or optimizations of existing ones) that
should improve the reach. Finally we comment on the potential for discovery at
the LHC.Comment: 41 pages, minor changes, added refs and discussion of previous
literatur
Affordability of medicines from the pharmaceutical system perspective : Comparative analysis of Finland and New Zealand
Tutkimuksessa tarkasteltiin lÀÀkekorvausjĂ€rjestelmien lÀÀkkeiden saatavuuteen vaikuttavia piirteitĂ€, erityisesti korvattavuuden ehtoja, disinsentiivejĂ€, korvattavaa valikoimaa ja universalismia, suhteessa lÀÀkeomavastuiden jakautumiseen ja hoitojen kĂ€yttĂ€mĂ€ttĂ€ jĂ€ttĂ€miseen kustannussyistĂ€. Aineistoina kĂ€ytettiin tuote- ja hinnastotietoja, kulutustutkimusaineistoa, postikyselyaineistoa ja apteekkien ostorekistereitĂ€. YhtĂ€lĂ€isyydet liittyivĂ€t universalismiin ja korvattavuuden ehtoihin. Korvauksia kohdennettiin molemmissa maissa tarpeeseen liittyvillĂ€ mekanismeilla, omavastuukaton avulla sekĂ€ korvattavuusrajoituksilla. Erot liittyivĂ€t valikoimaan ja disinsentiiveihin. Suomessa korvattiin enemmĂ€n hoidollisesti toisiaan lĂ€hellĂ€ olevia vaihtoehtoja ja uusien lÀÀkeÂinnovaatioiden mÀÀrĂ€ markkinoilla oli laajempi, mutta omavastuutaso korkeampi. Uudessa-Seelannissa kokonaan korvattavia lÀÀkkeitĂ€ oli saatavissa useimpiin terveysongelmiin. Korvattava valikoima oli kuitenkin kontrolloidumpi ja sisĂ€lsi enemmĂ€n vanhempia lÀÀkkeitĂ€. Suomessa omavastuilla oli regressiivisiĂ€ vaikutuksia. PienemmĂ€t tulot ja huonompi terveydentila olivat yhteydessĂ€ palveluiden kĂ€yttĂ€mĂ€ttĂ€ jĂ€ttĂ€miseen kustannussyistĂ€, mikĂ€ vastasi aiemmassa kirjallisuudessa Uudesta-Seelannista julkaistuja tuloksia. Omavastuiden jakautumisen perusteella Uudessa-Seelannissa ikÀÀntyneet henkilöt kĂ€yttivĂ€t vain harvoin muita kuin kokonaan korvattavia lÀÀkkeitĂ€ eivĂ€tkĂ€ korkeat omavastuut olleet yhteydessĂ€ potilaan sosioekonomiseen asemaan. Korkeammasta sairastavuudestaan huolimatta maoreilla (alkuperĂ€iskansa) kuitenkin korkeat omavastuut olivat harvinaisempia, ja he myös ostivat vĂ€hemmĂ€n lÀÀkkeitĂ€ eurooppalaistaustaisiin nĂ€hden. Kumpikin jĂ€rjestelmĂ€ sisĂ€ltÀÀ riittĂ€vyyteen liittyviĂ€ heikkouksia ja vahvuuksia eikĂ€ kumpikaan kykene tĂ€ysin suojaamaan potilaita omavastuiden haitallisilta vaikutuksilta. Sosioekonomisten ja etnisten lÀÀkkeiden kĂ€yttöön liittyvien erojen syiden ja seurausten selvittĂ€minen vaatii vielĂ€ lisÀÀ tutkimusta. - Englanninkielinen julkaisu.30,00 euro
Precision measurements of the top quark mass from the Tevatron in the pre-LHC era
The top quark is the heaviest of the six quarks of the Standard Model.
Precise knowledge of its mass is important for imposing constraints on a number
of physics processes, including interactions of the as yet unobserved Higgs
boson. The Higgs boson is the only missing particle of the Standard Model,
central to the electroweak symmetry breaking mechanism and generation of
particle masses. In this Review, experimental measurements of the top quark
mass accomplished at the Tevatron, a proton-antiproton collider located at the
Fermi National Accelerator Laboratory, are described. Topologies of top quark
events and methods used to separate signal events from background sources are
discussed. Data analysis techniques used to extract information about the top
mass value are reviewed. The combination of several most precise measurements
performed with the two Tevatron particle detectors, CDF and \D0, yields a value
of \Mt = 173.2 \pm 0.9 GeV/.Comment: This version contains the most up-to-date top quark mass averag
Scalar-mediated forward-backward asymmetry
A large forward-backward asymmetry in production, for large
invariant mass of the system, has been recently observed by the CDF
collaboration. Among the scalar mediated mechanisms that can explain such a
large asymmetry, only the t-channel exchange of a color-singlet weak-doublet
scalar is consistent with both differential and integrated cross
section measurements. Constraints from flavor changing processes dictate a very
specific structure for the Yukawa couplings of such a new scalar. No sizable
deviation in the differential or integrated production cross section
is expected at the LHC.Comment: 22 pages, 1 figure and 2 tables. v2: Corrected Eqs.(50,51,74),
adapted Fig.1, Tab.1 and relevant discussions. Extended discussion of top
decay and single to
Patient injuries in operative rhinology during a ten-year period : Review of national patient insurance charts
Objectives: To assess factors contributing to patient injuries in operative rhinology. Design: Data of the accepted patient injury claims involving operative rhinology, between the years 2001 and 2011, were obtained from the Finnish Patient Insurance Centre registry. Two senior otolaryngologists analysed and evaluated the injury mechanisms. Main outcome measures: Analysis and classification of factors contributing to patient injuries. Results: During the ten-year study period, there were 67 patient injuries in operative rhinology, comprising 36% of all patient injuries in otorhinolaryngologic surgery. The majority (78%) of patients were treated in university or central hospitals and almost all (90%) by fully trained otolaryngology specialists. The factors contributing to the injuries were errors in surgical technique, like lesions to the orbit, skull base and meninges, and adjacent nerves, as well as mistakes with removable packings left in situ. Nearly half of the patients had undergone endoscopic sinus surgery. One patient died because of bleeding from the intracranial artery. Fourteen patients (21%) needed a re-operation due to the injury. Conclusions: Patient injuries in rhinology were caused by typical complications of common operations performed by otorhinolaryngology specialists. The increased volume of endoscopic sinus surgery was evident also in patient injuries.Peer reviewe
Matching Tree-Level Matrix Elements with Interleaved Showers
We present an implementation of the so-called CKKW-L merging scheme for
combining multi-jet tree-level matrix elements with parton showers. The
implementation uses the transverse-momentum-ordered shower with interleaved
multiple interactions as implemented in PYTHIA8. We validate our procedure
using e+e--annihilation into jets and vector boson production in hadronic
collisions, with special attention to details in the algorithm which are
formally sub-leading in character, but may have visible effects in some
observables. We find substantial merging scale dependencies induced by the
enforced rapidity ordering in the default PYTHIA8 shower. If this rapidity
ordering is removed the merging scale dependence is almost negligible. We then
also find that the shower does a surprisingly good job of describing the
hardness of multi-jet events, as long as the hardest couple of jets are given
by the matrix elements. The effects of using interleaved multiple interactions
as compared to more simplistic ways of adding underlying-event effects in
vector boson production are shown to be negligible except in a few sensitive
observables. To illustrate the generality of our implementation, we also give
some example results from di-boson production and pure QCD jet production in
hadronic collisions.Comment: 44 pages, 23 figures, as published in JHEP, including all changes
recommended by the refere
Top quark and Electroweak measurements at the Tevatron
We present recent preliminary measurements at the Tevatron of t-tbar and
single top production cross section, top quark mass and width, top pair spin
correlations and forward-backward asymmetry. In the electroweak sector, we
present the Tevatron average of the W boson width, and preliminary measurements
of the W and Z forward-backward asymmetries and WZ, ZZ diboson production cross
sections. All measurements are based on larger amount of collision data than
previously used and are in agreement with the standard model.Comment: 6 pages, 6 figures; In proceedings of the 16th International
Symposium on Particles, Strings and Cosmology, Valencia (Spain) 201
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