7,873 research outputs found
Investigating The Physics Case of Running a B-Factory at the Y(5S) Resonance
We discuss the physics case of a high luminosity B-Factory running at the
Y(5S) resonance. We show that the coherence of the B meson pairs is preserved
at this resonance, and that Bs can be well distinguished from Bd and charged B
mesons. These facts allow to cover the physics program of a traditional
B-Factory and, at the same time, to perform complementary measurements which
are not accessible at the Y(4S). In particular we show how, despite the
experimental limitations in performing time-dependent measurements of Bs
decays, the same experimental information can be extracted, in several cases,
from the determination of time-integrated observables. In addition, a few
examples of the potentiality in measuring rare Bs decays are given. Finally, we
discuss how the study of Bs meson will improve the constraints on New Physics
parameters in the Bs sector, in the context of the generalized Unitarity
Triangle analysis.Comment: 47 pages, 22 figure
1.65 micrometers (H-band) surface photometry of galaxies. III: observations of 558 galaxies with the TIRGO 1.5m telescope
We present near-infrared H-band (1.65 micron) surface photometry of 558
galaxies in the Coma Supercluster and in the Virgo cluster. This data set,
obtained with the Arcetri NICMOS3 camera ARNICA mounted on the Gornergrat
Infrared Telescope, is aimed at complementing, with observations of mostly
early-type objects, our NIR survey of spiral galaxies in these regions,
presented in previous papers of this series. Magnitudes at the optical radius,
total magnitudes, isophotal radii and light concentration indices are derived.
We confirm the existence of a positive correlation between the near-infrared
concentration index and the galaxy H-band luminosity. (Tables 1 and 2 are only
available in electronic form upon request to [email protected])Comment: 12 pages, 6 figures. Accepted for publication in A&A
Deep learning for inferring cause of data anomalies
Daily operation of a large-scale experiment is a resource consuming task,
particularly from perspectives of routine data quality monitoring. Typically,
data comes from different sub-detectors and the global quality of data depends
on the combinatorial performance of each of them. In this paper, the problem of
identifying channels in which anomalies occurred is considered. We introduce a
generic deep learning model and prove that, under reasonable assumptions, the
model learns to identify 'channels' which are affected by an anomaly. Such
model could be used for data quality manager cross-check and assistance and
identifying good channels in anomalous data samples. The main novelty of the
method is that the model does not require ground truth labels for each channel,
only global flag is used. This effectively distinguishes the model from
classical classification methods. Being applied to CMS data collected in the
year 2010, this approach proves its ability to decompose anomaly by separate
channels.Comment: Presented at ACAT 2017 conference, Seattle, US
Constraints on new physics from the quark mixing unitarity triangle
The status of the Unitarity Triangle beyond the Standard Model including the
most recent results on Delta m_s, on dilepton asymmetries and on width
differences is presented. Even allowing for general New Physics loop
contributions the Unitarity Triangle must be very close to the Standard Model
result. With the new measurements from the Tevatron, we obtain for the first
time a significant constraint on New Physics in the B_s sector. We present the
allowed ranges of New Physics contributions to Delta F=2 processes, and of the
time-dependent CP asymmetry in B_s to J/Psi phi decays.Comment: 5 pages, 4 figures. v2: numerical error in Delta Gamma_s/Gamma_s
corrected. Plots and tables updated. v3: update after ICHEP06, final version
published in Phys Rev Letter
Dynamic HPLC on chiral stationary phases: a powerful tool for the investigation of stereomutation processes
Dynamic HPLC on enantioselective stationary phases has become a well-established technique to investigate chiral molecules with internal motions that result in stereoinversion and occur on the time scale of the separation process. Kinetic parameters
for the on-column interconversion phenomena can be extracted from experimental peak profiles by computer simulation or by direct calculation methods. The technique has been used in a wide range of temperatures and is complementary in scope to dynamic NMR spectroscopy
Ionic Push–Pull Polythiophenes: A Further Step towards Eco-Friendly BHJ Organic Solar Cells
Four new conjugated polymers alternating benzothiadiazole units and thiophene moieties functionalized with ionic phosphonium or sulfonic acid salts in the side chains were synthesized by a postfunctionalization approach of polymeric precursors. The introduction of ionic groups makes the conjugated polymers soluble in water and/or polar solvents, allowing for the fabrication of bulk heterojunction (BHJ) solar cells using environmentally friendly conditions. All polymers were fully characterized by spectroscopic, thermal, electrochemical, X-ray diffraction, scanning electron, and atomic force techniques. BHJ solar cells were obtained from halogen-free solvents (i.e., ethanol and/or anisole) by blending the synthesized ionic push–pull polymers with a serinol-fullerene derivative or an ionic homopolymer acting as electron-acceptor (EA) or electron-donor (ED) counterparts, respectively. The device with the highest optical density and the smoothest surface of the active layer was the best-performing, showing a 4.76% photoconversion efficiency
HLA Heterozygote Advantage against HIV-1 Is Driven by Quantitative and Qualitative Differences in HLA Allele-Specific Peptide Presentation.
Pathogen-mediated balancing selection is regarded as a key driver of host immunogenetic diversity. A hallmark for balancing selection in humans is the heterozygote advantage at genes of the human leukocyte antigen (HLA), resulting in improved HIV-1 control. However, the actual mechanism of the observed heterozygote advantage is still elusive. HLA heterozygotes may present a broader array of antigenic viral peptides to immune cells, possibly resulting in a more efficient cytotoxic T-cell response. Alternatively, heterozygosity may simply increase the chance to carry the most protective HLA alleles, as individual HLA alleles are known to differ substantially in their association with HIV-1 control. Here, we used data from 6,311 HIV-1-infected individuals to explore the relative contribution of quantitative and qualitative aspects of peptide presentation in HLA heterozygote advantage against HIV. Screening the entire HIV-1 proteome, we observed that heterozygous individuals exhibited a broader array of HIV-1 peptides presented by their HLA class I alleles. In addition, viral load was negatively correlated with the breadth of the HIV-1 peptide repertoire bound by an individual's HLA variants, particularly at HLA-B. This suggests that heterozygote advantage at HLA-B is at least in part mediated by quantitative peptide presentation. We also observed higher HIV-1 sequence diversity among HLA-B heterozygous individuals, suggesting stronger evolutionary pressure from HLA heterozygosity. However, HLA heterozygotes were also more likely to carry certain HLA alleles, including the highly protective HLA-B*57:01 variant, indicating that HLA heterozygote advantage ultimately results from a combination of quantitative and qualitative effects in antigen presentation
Improved Determination of the CKM Angle alpha from B to pi pi decays
Motivated by a recent paper that compares the results of the analysis of the
CKM angle alpha in the frequentist and in the Bayesian approaches, we have
reconsidered the information on the hadronic amplitudes, which helps
constraining the value of alpha in the Standard Model. We find that the
Bayesian method gives consistent results irrespective of the parametrisation of
the hadronic amplitudes and that the results of the frequentist and Bayesian
approaches are equivalent when comparing meaningful probability ranges or
confidence levels. We also find that from B to pi pi decays alone the 95%
probability region for alpha is the interval [80^o,170^o], well consistent with
recent analyses of the unitarity triangle where, by using all the available
experimental and theoretical information, one gets alpha = (93 +- 4)^o. Last
but not least, by using simple arguments on the hadronic matrix elements, we
show that the unphysical region alpha ~ 0, present in several experimental
analyses, can be eliminated.Comment: 16 pages, 7 figure
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