143 research outputs found
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Searches for New Physics at the Tevatron and LHC
This is an auspicious moment in experimental particle physics - there are large data samples at the Tevatron and a new energy regime being explored at the Large Hadron Collider with ever larger data samples. The coincidence of these two events suggests that we will soon be able to address the question, what lies beyond the standard model? Particle physics's current understanding of the universe is embodied in it. The model has been tested to extreme precision - better than a part in ten thousand - but we suspect that it is only an approximation, and that physics beyond this standard model will appear in the data of the Tevatron and LHC in the near future. This brief review touches on the status of searches for new physics at the time of the conference
Charmed meson decay constants in three-flavor lattice QCD
We present the first lattice QCD calculation with realistic sea quark content
of the D^+ meson decay constant f_{D^+}. We use the MILC Collaboration's
publicly available ensembles of lattice gauge fields, which have a quark sea
with two flavors (up and down) much lighter than a third (strange). We obtain
f_{D^+} = 201 +/- 3 +/- 17 MeV, where the errors are statistical and a
combination of systematic errors. We also obtain f_{D_s} = 249 +/- 3 +/- 16 MeV
for the D_s meson.Comment: note added on recent CLEO measurement; PRL versio
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Collider signature of T-quarks
Little Higgs models with T Parity contain new vector-like fermions, the T-odd quarks or ''T-quarks'', which can be produced at hadron colliders with a QCD-strength cross section. Events with two acoplanar jets and large missing transverse energy provide a simple signature of T-quark production. We show that searches for this signature with the Tevatron Run II data can probe a significant part of the Little Higgs model parameter space not accessible to previous experiments, exploring T-quark masses up to about 400 GeV. This reach covers parts of the parameter space where the lightest T-odd particle can account for the observed dark matter relic abundance. We also comment on the prospects for this search at the Large Hadron Collider (LHC)
Influence heat-reflective coating on the decrease of heat losses of window constructions
Developed theoretical and methodological foundations of the optimal choice of space-planning and constructive decisions of low-rise buildings blocked type, aimed at improving efficiency of investment, energy and resource saving, creation of comfortable conditions for the population, ensure sustainable development of low-rise construction in the context of socio-economic priorities in the climatic zoning of the area of construction
The first spectral line surveys searching for signals from the Dark Ages
Our aim is to observationally investigate the cosmic Dark Ages in order to
constrain star and structure formation models, as well as the chemical
evolution in the early Universe. Spectral lines from atoms and molecules in
primordial perturbations at high redshifts can give information about the
conditions in the early universe before and during the formation of the first
stars in addition to the epoch of reionisation. The lines may arise from moving
primordial perturbations before the formation of the first stars (resonant
scattering lines), or could be thermal absorption or emission lines at lower
redshifts. The difficulties in these searches are that the source redshift and
evolutionary state, as well as molecular species and transition are unknown,
which implies that an observed line can fall within a wide range of
frequencies. The lines are also expected to be very weak. Observations from
space have the advantages of stability and the lack of atmospheric features
which is important in such observations. We have therefore, as a first step in
our searches, used the Odin satellite to perform two sets of spectral line
surveys towards several positions. The first survey covered the band 547-578
GHz towards two positions, and the second one covered the bands 542.0-547.5 GHz
and 486.5-492.0 GHz towards six positions selected to test different sizes of
the primordial clouds. Two deep searches centred at 543.250 and 543.100 GHz
with 1 GHz bandwidth were also performed towards one position. The two lowest
rotational transitions of H2 will be redshifted to these frequencies from
z~20-30, which is the predicted epoch of the first star formation. No lines are
detected at an rms level of 14-90 and 5-35 mK for the two surveys,
respectively, and 2-7 mK in the deep searches with a channel spacing of 1-16
MHz. The broad bandwidth covered allows a wide range of redshifts to be
explored for a number of atomic and molecular species and transitions. From the
theoretical side, our sensitivity analysis show that the largest possible
amplitudes of the resonant lines are about 1 mK at frequencies <200 GHz, and a
few micro K around 500-600 GHz, assuming optically thick lines and no
beam-dilution. However, if existing, thermal absorption lines have the
potential to be orders of magnitude stronger than the resonant lines. We make a
simple estimation of the sizes and masses of the primordial perturbations at
their turn-around epochs, which previously has been identified as the most
favourable epoch for a detection. This work may be considered as an important
pilot study for our forthcoming observations with the Herschel Space
Observatory.Comment: 15 pages, 9 figures, 3 on-line pages. Accepted for publication in
Astronomy & Astrophysics 8 March 2010
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Functional Requirements on the Design of the Detectors and the Interaction Region of an e e- Linear Collider with a Push-Pull Arrangement of Detectors
The Interaction Region of the International Linear Collider is based on two experimental detectors working in a push-pull mode. A time efficient implementation of this model sets specific requirements and challenges for many detector and machine systems, in particular the IR magnets, the cryogenics and the alignment system, the beamline shielding, the detector design and the overall integration. This paper attempts to separate the functional requirements of a push pull interaction region and machine detector interface from any particular conceptual or technical solution that might have been proposed to date by either the ILC Beam Delivery Group or any of the three detector concepts. As such, we hope that it provides a set of ground rules for interpreting and evaluating the MDI parts of the proposed detector concept's Letters of Intent, due March 2009. The authors of the present paper are the leaders of the IR Integration Working Group within Global Design Effort Beam Delivery System and the representatives from each detector concept submitting the Letters Of Intent
Mrk 609: resolving the circum-nuclear structure with near-infrared integral field spectroscopy
We present first results of near infrared J and H+K ESO-SINFONI integral
field spectroscopy of the composite starburst/Seyfert 1.8 galaxy Mrk 609. The
data were taken during the science verification period of SINFONI. We aim to
investigate the morphology and excitation conditions within the central 2 kpc.
Additional Nobeyama 45 m CO(1-0) data are presented, which we used to estimate
the molecular gas mass. The source was selected from a sample of adaptive
optics suitable, SDSS/ROSAT based, X-ray bright AGN with redshifts of 0.03 < z
< 1. This sample allows for a detailed study of the NIR properties of the
nuclear and host environments with high spectral and spatial resolution. Our
NIR data reveal a complex emission-line morphology, possibly associated with a
nuclear bar seen in the reconstructed continuum images. The detections of
[SiVI] and a broad Pa alpha component are clear indicators for the presence of
an accreting super-massive black hole at the center of Mrk 609. In agreement
with previous observations we find that the circum-nuclear emission is not
significantly extincted. The analysis of the high angular resolution
rotational-vibrational molecular hydrogen and forbidden [FeII] emission reveals
a LINER character of the nucleus. The large H_2 gas mass deduced from the
CO(1-0) observation provides the fuel needed to feed the starburst and Seyfert
activity in Mrk 609. High angular resolution imaging spectroscopy provides an
ideal tool to resolve the nuclear and starburst contribution in active
galaxies. We show that Mrk 609 exhibits LINER features, that appear to be
hidden in larger aperture visible/NIR spectra.Comment: published by A&A, 19 pages, 16 figures, version with high resolution
figures is available via http://www.ph1.uni-koeln.de/~zuther/mrk609.pd
A systematic review of correlates of sedentary behaviour in adults aged 18–65 years: a socio-ecological approach
Background: Recent research shows that sedentary behaviour is associated with adverse cardio-metabolic consequences even among those considered sufficiently physically active. In order to successfully develop interventions to address this unhealthy behaviour, factors that influence sedentariness need to be identified and fully understood. The aim of this review is to identify individual, social, environmental, and policy-related determinants or correlates of sedentary behaviours among adults aged 18-65 years. Methods: PubMed, Embase, CINAHL, PsycINFO and Web of Science were searched for articles published between January 2000 and September 2015. The search strategy was based on four key elements and their synonyms: (a) sedentary behaviour (b) correlates (c) types of sedentary behaviours (d) types of correlates. Articles were included if information relating to sedentary behaviour in adults (18-65 years) was reported. Studies on samples selected by disease were excluded. The full protocol is available from PROSPERO (PROSPERO 2014:CRD42014009823). Results: 74 original studies were identified out of 4041: 71 observational, two qualitative and one experimental study. Sedentary behaviour was primarily measured as self-reported screen leisure time and total sitting time. In 15 studies, objectively measured total sedentary time was reported: accelerometry (n = 14) and heart rate (n = 1). Individual level factors such as age, physical activity levels, body mass index, socio-economic status and mood were all significantly correlated with sedentariness. A trend towards increased amounts of leisure screen time was identified in those married or cohabiting while having children resulted in less total sitting time. Several environmental correlates were identified including proximity of green space, neighbourhood walkability and safety and weather. Conclusions: Results provide further evidence relating to several already recognised individual level factors and preliminary evidence relating to social and environmental factors that should be further investigated. Most studies relied upon cross-sectional design limiting causal inference and the heterogeneity of the sedentary measures prevented direct comparison of findings. Future research necessitates longitudinal study designs, exploration of policy-related factors, further exploration of environmental factors, analysis of inter-relationships between identified factors and better classification of sedentary behaviour domains
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Benchmarking / Crosschecking DFS in the ILC Main Linac
In an effort to compare beam dynamics and create a ''benchmark'' for Dispersion Free Steering (DFS) a comparison was made between different ILC simulation programs while performing DFS. This study consisted of three parts. First, a simple betatron oscillation was tracked through each code. Secondly, a set of component misalignments and corrector settings generated from one program was read into the others to confirm similar emittance dilution. Thirdly, given the same set of component misalignments DFS was performed independently in each program and the resulting emittance dilution was compared. Performance was found to agree exceptionally well in all three studies
Substantial Alterations of the Cutaneous Bacterial Biota in Psoriatic Lesions
For psoriasis, an idiopathic inflammatory disorder of the skin, the microbial biota has not been defined using cultivation-independent methods. We used broad-range 16S rDNA PCR for archaea and bacteria to examine the microbiota of normal and psoriatic skin. From 6 patients, 19 cutaneous samples (13 from diseased skin and 6 from normal skin) were obtained. Extracted DNA was subjected to the broad range PCR, and 1,925 cloned products were compared with 2,038 products previously reported from healthy persons. Using 98% sequence identity as a species boundary, 1,841 (95.6%) clones were similar to known bacterial 16S rDNA, representing 6 phyla, 86 genera, or 189 species-level operational taxonomic unit (SLOTU); 84 (4.4%) clones with <98% identity probably represented novel species. The most abundant and diverse phylum populating the psoriatic lesions was Firmicutes (46.2%), significantly (P<0.001) overrepresented, compared to the samples from uninvolved skin of the patients (39.0%) and healthy persons (24.4%). In contrast, Actinobacteria, the most prevalent and diverse phylum in normal skin samples from both healthy persons (47.6%) and the patients (47.8%), was significantly (P<0.01) underrepresented in the psoriatic lesion samples (37.3%). Representation of Propionibacterium species were lower in the psoriatic lesions (2.9±5.5%) than from normal persons (21.1±18.2%; P<0.001), whereas normal skin from the psoriatic patients showed intermediate levels (12.3±21.6%). We conclude that psoriasis is associated with substantial alteration in the composition and representation of the cutaneous bacterial biota
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