237 research outputs found
On Sterile neutrino explanation of LSND and MiniBooNE anomalies
We examine the compatibility between existing experimental data and a
recently proposed explanation of the LSND and MiniBooNE anomalies, given in
terms of a sterile neutrino whose decay is dominated by a radiative mode.
We find that current experimental data on
decays are compatible with the sterile neutrino parameters required for the
explanation of the anomalies, but shows a marginal
tension with those parameters. We also propose experimental cuts on radiative
decays that could test the sterile neutrino hypothesis better. Finally, we
study the contribution of this sterile neutrino to , and find
that measurements of this process would provide powerful tests for the sterile
neutrino explanation of the LSND and MiniBooNE anomalies, if the experimental
cut on the invariant mass of the pair could be reduced from its
current value of 145 MeV to a value below 40 MeV.Comment: 6 pages, 2 figures, experimental cut taken into account, some
conclusions change
Neutrinoless double beta decay and lepton number violation at the LHC
10.1103/PhysRevD.88.011901This work was supported by EU Network Grant No. UNILHC PITN-GA-2009-237920 and by the Spanish MICINN Grants No. FPA2011-22975 and No. MULTIDARK CSD2009-00064, by the Generalitat Valenciana (Prometeo/2009/091), by Fondecyt Grants No. 11121557 and No. 1100582, and CONICYT Projects No. 791100017 and No. CONICYT/DFG-648. H. P. was supported by DGF Grant No. PA 803/6-1.Peer reviewe
A Simulation Study of Spectral Cerenkov Luminescence Imaging for Tumour Margin Estimation
Breast cancer is the most common cancer in women in the world. Breast-conserving surgery (BCS) is a standard surgical treatment for breast cancer with the key objective of removing breast tissue, maintaining a negative surgical margin and providing a good cosmetic outcome. A positive surgical margin, meaning the presence of cancerous tissues on the surface of the breast specimen after surgery, is associated with local recurrence after therapy. In this study, we investigate a new imaging modality based on Cerenkov luminescence imaging (CLI) for the purpose of detecting positive surgical margins during BCS. We develop Monte Carlo (MC) simulations using the Geant4 nuclear physics simulation toolbox to study the spectrum of photons emitted given 18F-FDG and breast tissue properties. The resulting simulation spectra show that the CLI signal contains information that may be used to estimate whether the cancerous cells are at a depth of less than 1 mm or greater than 1 mm given appropriate imaging system design and sensitivity. The simulation spectra also show that when the source is located within 1 mm of the surface, the tissue parameters are not relevant to the model as the spectra do not vary significantly. At larger depths, however, the spectral information varies significantly with breast optical parameters, having implications for further studies and system design. While promising, further studies are needed to quantify the CLI response to more accurately incorporate tissue specific parameters and patient specific anatomical details
Bayesian Estimation of Intrinsic Tissue Oxygenation and Perfusion from RGB Images
Multispectral imaging (MSI) can potentially assist the intra-operative assessment of tissue structure, function and viability, by providing information about oxygenation. In this paper, we present a novel technique for recovering intrinsic MSI measurements from endoscopic RGB images without custom hardware adaptations. The advantage of this approach is that it requires no modification to existing surgical and diagnostic endoscopic imaging systems. Our method uses a radiometric colour calibration of the endoscopic camera's sensor in conjunction with a Bayesian framework to recover a per-pixel measurement of the total blood volume (THb) and oxygen saturation (SO2) in the observed tissue. The sensor's pixel measurements are modelled as weighted sums over a mixture of Poisson distributions and we optimise the variables SO2 and THb to maximise the likelihood of the observations. To validate our technique, we use synthetic images generated from Monte Carlo (MC) physics simulation of light transport through soft tissue containing sub-surface blood vessels. We also validate our method on in vivo data by comparing it to a MSI dataset acquired with a hardware system that sequentially images multiple spectral bands without overlap. Our results are promising and show that we are able to provide surgeons with additional relevant information by processing endoscopic images with our modelling and inference framework
Heavy neutrino searches at the LHC with displaced vertices
Sterile neutrinos with masses in the range of 1¿100 GeV have been searched for in a variety of experiments. Here, we discuss the prospects of searching for sterile neutrinos at the LHC using displaced vertices. Two different cases are discussed: (i) the standard model extended with sterile neutrinos, and (ii) right-handed neutrinos in a left-right symmetric extension of the standard model. A dedicated displaced vertex search will allow us to probe parts of the parameter space not accessible to other searches, but both cases will require a large luminosity
On sterile neutrino mixing with \nu_{\tau}
Matrix element of sterile neutrino N mixing with is
the least constrained in the literature among the three
() mixing parameters characterizing the sterile neutrino
phenomenology. We study the contribution of massive dominantly sterile
neutrinos to purely leptonic -decays and semileptonic decays of
and K, D mesons. We consider some decays allowed in the Standard Model (SM) as
well as Lepton Flavor and Lepton Number Violating (LFV, LNV) decays forbidden
in the SM. From the existing experimental data on the branching ratios of these
processes we derived new limits on more stringent than the ones
existing in the literature. These limits are extracted in a model independent
way without any ad hoc assumptions on the relative size of the three different
sterile neutrino mixing parameters.Comment: 14 pages, 6 figures. arXiv admin note: text overlap with
arXiv:1005.160
Proceedings of the 2nd Workshop on Flavor Symmetries and Consequences in Accelerators and Cosmology (FLASY12)
These are the proceedings of the 2nd Workshop on Flavor Symmetries and
Consequences in Accelerators and Cosmology, held 30 June 2012 - 4 July 2012,
Dortmund, Germany.Comment: Order 400 pages, several figures including the group picture v2:
corrected author list and contributio
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