Search results for "Helicity"

Flavour Separation of Helicity Distributions from Deep Inelastic Muon-Deuteron Scattering

2009

We present a LO evaluation of helicity densities of valence, \Delta u_v+\Delta d_v, non-strange sea, \Delta\bar{u}+\Delta\bar{d}, and strange quarks, \Delta s (assumed to be equal to \Delta\bar{s}). They have been obtained from the inclusive asymmetry A_{3,d} and the semi-inclusive asymmetries A^{\pi+}_{1,d}, A^{\pi-}_{1,d}, A^{K+}_{1,d}, A^{K-}_{1,d} measured in polarised deep inelastic muon-deuteron scattering. The full deuteron statistics of COMPASS (years 2002-2004 and 2006) has been used. The data cover the range Q^2 > 1 (GeV/c)^2 and 0.004<x<0.3. Both non-strange densities are found to be in a good agreement with previous measurements. The distribution of \Delta s(x) is compatible wit…

Search for anomalous top-quark couplings with the D0 detector

2008

Anomalous Wtb couplings modify the angular correlations of the top quark decay products and change the single top quark production cross section. We present limits on anomalous top quark couplings by combining information from W boson helicity measurements in top quark decays and anomalous coupling searches in the single top quark final state. We set limits on right-handed vector couplings as well as left-handed and right-handed tensor couplings based on about 1fb^-1 of data collected by the D0 experiment.

Synergy of Axial and Point Chirality to Construct Helical N -Heterotriangulene-Based Supramolecular Polymers

2018

Homochiral self-assembly of biocoordination polymers: anion-triggered helicity and absolute configuration inversion

2015

The different natures of the weakly coordinating anions – triflate or perchlorate – in the Cu2+-mediated self-assembly of cytidine monophosphate nucleotide play a fundamental role in the homochiral resolution process, yielding one-dimensional copper(II) coordination polymers of opposite helicity that can be easily inverted, in a reversible way, by changing the nature of the anion as revealed by circular dichroism experiments both in solution and in the solid state.

Frontispiece: Hierarchy of Asymmetry at Work: Chain-Dependent Helix-to-Helix Interactions in Supramolecular Polymers

2018

First measurement of quarkonium polarization in nuclear collisions at the LHC

2021

The polarization of inclusive J/$\psi$ and $\Upsilon(1{\rm S})$ produced in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}=5.02$ TeV at the LHC is measured with the ALICE detector. The study is carried out by reconstructing the quarkonium through its decay to muon pairs in the rapidity region $2.5<y<4$ and measuring the polar and azimuthal angular distributions of the muons. The polarization parameters $\lambda_{\theta}$, $\lambda_{\phi}$ and $\lambda_{\theta\phi}$ are measured in the helicity and Collins-Soper reference frames, in the transverse momentum interval $2<p_{\rm T}<10$ GeV/$c$ and $p_{\rm T}<15$ GeV/$c$ for the J/$\psi$ and $\Upsilon(1{\rm S})$, respectively. The polarization parameter…

Measurement of top quark and W boson polarisation observables with t-channel single-top-quark events in the ATLAS experiment

2017

El trabajo de la tesis se enmarca dentro del programa de física de la Colaboración ATLAS para el análisis de los datos producidos por el Gran Colisionador de Hadrones (LHC) situado en el CERN. La primera parte del trabajo desarrollado se centra en los estudios realizados para mejorar los algoritmos y el procedimiento seguido para el alineamiento del detector de trazas de ATLAS. El conocimiento de la posición exacta que ocupan los elementos que componen el detector de trazas determina la resolución con la que la trayectoria de una partícula puede ser reconstruida. La posición de dichos elementos se ve afectada por cambios en las condiciones de trabajo, como el apagado y encendido del sistema…

One-loop corrections to light cone wave functions: the dipole picture DIS cross section

2018

We develop methods needed to perform loop calculations in light cone perturbation theory using a helicity basis, refining the method introduced in our earlier work. In particular this includes implementing a consistent way to contract the four-dimensional tensor structures from the helicity vectors with d-dimensional tensors arising from loop integrals, in a way that can be fully automatized. We demonstrate this explicitly by calculating the one-loop correction to the virtual photon to quark-antiquark dipole light cone wave function. This allows us to calculate the deep inelastic scattering cross section in the dipole formalism to next-to-leading order accuracy. Our results, obtained using …