scholarly journals Recent results from the CBELSA/TAPS experiment at ELSA

2020 ◽  
Vol 241 ◽  
pp. 01001
Author(s):  
Farah Afzal
Keyword(s):  
Final States ◽  
Excitation Spectra ◽  
Unpolarized Cross Section ◽  
Polarized Target ◽  
Double Polarization ◽  
Perturbative Regime ◽  
Measured Polarization ◽  
Polarization Observables ◽  
The Impact ◽  
Photoproduction Reactions

In order to gain a better understanding of the dynamics inside the nucleon and of the non-perturbative regime of QCD, the nucleon excitation spectra and the properties of nucleon resonances are investigated. An essential experimental tool to achieve this goal is the study of different photoproduction reactions. Partial wave analyses are performed in order to obtain information about the contributing resonances. A complete experiment is needed to extract the underlying amplitudes unambiguously, which requires the measurement of carefully chosen single and double polarization observables in addition to the unpolarized cross section. The CBELSA/TAPS experiment in Bonn offers the possibility to measure several polarization observables using a linearly or circularly polarized photon beam and with a longitudinally or transversely polarized target. This contribution gives an overview of recently measured polarization observables in different final states. The impact of the new data is discussed.

scholarly journals POLARIZATION OBSERVABLES FOR K+Λ AND K+Σ0 PHOTOPRODUCTION FROM POLARIZED PROTONS

2014 ◽  
Vol 26 ◽  
pp. 1460098
Author(s):  
◽  
NATALIE K. WALFORD ◽  
FRANZ J. KLEIN
Keyword(s):  
Excited States ◽  
Final States ◽  
Polarization Data ◽  
Polarized Protons ◽  
Model Predictions ◽  
Double Polarization ◽  
Model Independent ◽  
Polarization Observables ◽  
Large Effort ◽  
Polarized Photons

The search for undiscovered excited states of the nucleon continues to be a focus of experiments at Jefferson Lab. Recent LQCD calculations have confirmed long-standing quark-model predictions of many more states than have so far been identified.1 A large effort for the N* program has been launched using the CLAS detector to provide the database that will allow nearly model-independent partial wave analyses to be carried out in the search for such states. Polarization observables play a crucial role in this effort, as they are essential in disentangling overlapping resonant and non-resonant amplitudes. In 2010, double-polarization data were taken at JLab using circularly polarized photons incident on a transversely polarized frozen-spin butanol target.2 Our current analysis yields preliminary data of the T and F asymmetries of the K+Λ and K+Σ0 final states, which are compared to predictions of recent multipole analyses. This work is the first of its kind and will significantly broaden the world database for these reactions.

scholarly journals Vibro-Acoustical Sensitivities of Stiffened Aircraft Structures Due to Attached Mass-Spring-Dampers with Uncertain Parameters

Aerospace ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 174
Author(s):  
Johannes Seidel ◽  
Stephan Lippert ◽  
Otto von Estorff
Keyword(s):  
System Response ◽  
Fuzzy Arithmetic ◽  
Parameter Uncertainties ◽  
Excitation Spectra ◽  
Radiated Noise ◽  
Linking Elements ◽  
Manufacturing Tolerances ◽  
Suitable Framework ◽  
Mass Spring ◽  
The Impact

The slightest manufacturing tolerances and variances of material properties can indeed have a significant impact on structural modes. An unintentional shift of eigenfrequencies towards dominant excitation frequencies may lead to increased vibration amplitudes of the structure resulting in radiated noise, e.g., reducing passenger comfort inside an aircraft’s cabin. This paper focuses on so-called non-structural masses of an aircraft, also known as the secondary structure that are attached to the primary structure via clips, brackets, and shock mounts and constitute a significant part of the overall mass of an aircraft’s structure. Using the example of a simplified fuselage panel, the vibro-acoustical consequences of parameter uncertainties in linking elements are studied. Here, the fuzzy arithmetic provides a suitable framework to describe uncertainties, create combination matrices, and evaluate the simulation results regarding target quantities and the impact of each parameter on the overall system response. To assess the vibrations of the fuzzy structure and by taking into account the excitation spectra of engine noise, modal and frequency response analyses are conducted.

scholarly journals General helicity formalism for two-hadron production in e+e− annihilation within a TMD approach

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Umberto D’Alesio ◽  
Francesco Murgia ◽  
Marco Zaccheddu
Keyword(s):  
Transverse Momentum ◽  
Hadron Production ◽  
Probabilistic Interpretation ◽  
Leading Order ◽  
Transverse Momentum Dependent ◽  
Factorization Scheme ◽  
Helicity Formalism ◽  
Double Polarization ◽  
Fragmentation Functions ◽  
Polarization Observables

Abstract We present the complete leading-order results for the azimuthal dependences and polarization observables in e+e−→ h1h2 + X processes, where the two hadrons are produced almost back-to-back, within a transverse momentum dependent (TMD) factorization scheme. We consider spinless (or unpolarized) and spin-1/2 hadron production and give the full set of the corresponding quark and gluon TMD fragmentation functions (TMD-FFs). By adopting the helicity formalism, which allows for a more direct probabilistic interpretation, single- and double-polarization cases are discussed in detail. Simplified expressions, useful for phenomenological analyses, are obtained by assuming a factorized Gaussian-like dependence on intrinsic transverse momenta for the TMD-FFs.

scholarly journals DETERMINATION OF E AND G OBSERVABLES IN η PHOTOPRODUCTION ON THE CLAS FROZEN SPIN TARGET (FROST)

2014 ◽  
Vol 26 ◽  
pp. 1460115
Author(s):  
◽  
IGOR SENDEROVICH ◽  
B. T. MORRISON ◽  
M. DUGGER ◽  
B. RITCHIE ◽  
...  
Keyword(s):  
Baryon Spectrum ◽  
Preliminary Results ◽  
Extensive Data ◽  
Polarized Protons ◽  
The World ◽  
Double Polarization ◽  
Linearly Polarized ◽  
Beam Incident ◽  
Polarization Observables

Polarization observables are vital for disentangling overlapping resonances in the baryon spectrum. Extensive data have been collected at Jefferson Lab in Hall B with circularly and linearly polarized tagged photon beam incident on longitudinally polarized protons provided by the Frozen Spin Target (FROST). The focus of the described work is on η photoproduction, which acts as an "isospin filter", isolating the N*(I = 1/2) resonances. Preliminary results for the double-polarization observables E and G are presented. There are currently no data on these in the world database for η photoproduction.

THE IMPACT OF LO, NLO AND NNLO FOR THE HIGGS SEARCHING AT $\sqrt{s} = 7$ TeV OF LHC

2010 ◽  
Vol 25 (36) ◽  
pp. 3027-3031
Author(s):  
JIAN WANG ◽  
GUOMING CHEN ◽  
WEIMIN WU
Keyword(s):  
Monte Carlo ◽  
Cross Section ◽  
Higgs Mass ◽  
Monte Carlo Generator ◽  
Final States ◽  
Leading Order ◽  
Analysis Process ◽  
Signal Rate ◽  
Monte Carlo Studies ◽  
The Impact

Most of current Monte Carlo studies on the Higgs searching are based on LO, or NLO calculation. However, in recent years, the next-to-next-to-leading order (NNLO) corrections have been computed for some physics process, and found that the cross section increases the kinematics changes. As the results, the analysis results could be impacted by these high order QCD corrections. We use standard Monte Carlo generator for LO, as well as MC@NLO for NLO and ResBos for NNLO at 7 TeV of LHC to evaluate this impact for physics channel of the Higgs, mass at 165 GeV, to WW, then W decay to lepton and neutrino as the final states. We found the signal rate could be effected by ratio of 1:2.6:3.4 for LO, NLO and NNLO using the same standard H→WW→lνlν searching analysis process.6

scholarly journals The fate of $$\mathbf{V}_\mathbf{1}$$ vector leptoquarks: the impact of future flavour data

2021 ◽  
Vol 81 (12) ◽  
Author(s):  
C. Hati ◽  
J. Kriewald ◽  
J. Orloff ◽  
A. M. Teixeira
Keyword(s):  
Simplified Model ◽  
Meson Decay ◽  
Final States ◽  
Decay Modes ◽  
Flavour Violation ◽  
Belle Ii ◽  
The Impact ◽  
Lepton Flavour ◽  
Model Approach

AbstractMotivated by the recent experimental progress on the B-meson decay anomalies (in particular the angular observables in $$B\rightarrow K^*\mu \mu $$ B → K ∗ μ μ ), we rely on a simplified-model approach to study the prospects of vector leptoquarks in what concerns numerous flavour observables, identifying several promising decay modes which would allow to (indirectly) probe such an extension. Our findings suggest that the confirmation of the B-meson decay anomalies, in parallel with positive signals (at Belle II or LHCb) for $$\tau \rightarrow \phi \mu $$ τ → ϕ μ , $$B_{(s)}$$ B ( s ) -meson decays to $$\tau ^+ \tau ^-$$ τ + τ - and $$\tau ^+ \mu ^-$$ τ + μ - ($$\tau ^+ e^-$$ τ + e - ) final states, as well as an observation of certain charged lepton flavour violation decays (at COMET or Mu2e), would contribute to strengthen the case for this scenario. We also illustrate how the evolution of the experimental determination of $$R_{D^{(*)}}$$ R D ( ∗ ) could be instrumental in falsifying an explanation of the anomalous B-meson decay data via a vector $$V_1$$ V 1 leptoquark.

scholarly journals PROBING THE IMPACT OF GAMMA-IRRADIATION ON THE METABOLIC STATE OF NEURAL STEM AND PRECURSOR CELLS USING DUAL-WAVELENGTH INTRINSIC SIGNAL TWO-PHOTON EXCITED FLUORESCENCE

2011 ◽  
Vol 04 (03) ◽  
pp. 289-300 ◽  
Author(s):  
TATIANA B. KRASIEVA ◽  
ERICH GIEDZINSKI ◽  
KATHERINE TRAN ◽  
MARY LAN ◽  
CHARLES L. LIMOLI ◽  
...  
Keyword(s):  
Gamma Irradiation ◽  
Fluorescence Intensity ◽  
Low Dose ◽  
Cellular Proliferation ◽  
Precursor Cells ◽  
High Dose ◽  
Excitation Spectra ◽  
Metabolic State ◽  
Two Photon ◽  
The Impact

Two-photon excited fluorescence (TPEF) spectroscopy and imaging were used to investigate the effects of gamma-irradiation on neural stem and precursor cells (NSPCs). While the observed signal from reduced nicotinamide adenine dinucleotide (NADH) was localized to the mitochondria, the signal typically associated with oxidized flavoproteins (Fp) was distributed diffusely throughout the cell. The measured TPEF emission and excitation spectra were similar to the established spectra of NAD(P)H and Fp. Fp fluorescence intensity was markedly increased by addition of the electron transport chain (ETC) modulator menadione to the medium, along with a concomitant decrease in the NAD(P)H signal. Three-dimensional (3D) neurospheres were imaged to obtain the cellular metabolic index (CMI), calculated as the ratio of Fp to NAD(P)H fluorescence intensity. Radiation effects were found to differ between low-dose (≤ 50 cGy) and high-dose (≥ 50 cGy) exposures. Low-dose irradiation caused a marked drop in CMI values accompanied by increased cellular proliferation. At higher doses, both NAD(P)H and Fp signals increased, leading to an overall elevation in CMI values. These findings underscore the complex relationship between radiation dose, metabolic state, and proliferation status in NSPCs and highlight the ability of TPEF spectroscopy and imaging to characterize metabolism in 3D spheroids.

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