Search results for "QUANTUM CHROMODYNAMICS"
showing 10 items of 1027 documents
Predictions for 5.023 TeV Pb + Pb collisions at the CERN Large Hadron Collider
2016
We compute predictions for various low-transverse-momentum bulk observables in √sNN = 5.023 TeV Pb+Pb collisions at the CERN Large Hadron Collider (LHC) from the event-by-event next-to-leading-order perturbative-QCD + saturation + viscous hydrodynamics (“EKRT”) model. In particular, we consider the centrality dependence of charged hadron multiplicity, flow coefficients of the azimuth-angle asymmetries, and correlations of event-plane angles. The centrality dependencies of the studied observables are predicted to be very similar to those at 2.76 TeV, and the magnitudes of the flow coefficients and event-plane angle correlations are predicted to be close to those at 2.76 TeV. The flow coeffic…
Axion Searches with Microwave Filters: the RADES project
2018
We propose, design and construct a variant of the conventional axion haloscope concept that could be competitive in the search for dark matter axions of masses in the decade 10–100 μeV. Theses masses are located somewhat above the mass range in which existing experiments have reached sensitivity to benchmark QCD axion models. Our haloscope consists of an array of small microwave cavities connected by rectangular irises, in an arrangement commonly used in radio-frequency filters. The size of the unit cavity determines the main resonant frequency, while the possibility to connect a large number of cavities allows to reach large detection volumes. We develop the theoretical framework of the de…
Small-x, Diffraction and Vector Mesons
2015
This talk discusses recent progress in some topics relevant for deep inelastic scattering at small x. We discuss first differences and similarities between conventional collinear factorization and the dipole picture of deep inelastic scattering. Many of the recent theoretical advances at small x are related to taking calculations in the nonlinear saturation regime to next-to-leading order accuracy in the QCD coupling. On the experimental side significant recent progress has been made in exclusive and diffractive processes, in particular in ultraperipheral nucleus-nucleus collisions.
QCD sum rule calculation ofK ℓ3 form factors
1992
We present a combined finite energy sum rule (FESR) and analytic continuation by duality (ACD) calculation of the (neutral)K l3 decay. We confirm the Callan-Treiman relation and investigate the validity of a linear fit for the form factors. Furthermore, we obtain ζ=−0.1...−0.3, consistent with the mean experimental value ζ=−0.1±0.09.
First Measurement of Transverse-Spin-Dependent Azimuthal Asymmetries in the Drell-Yan Process
2017
The first measurement of transverse-spin-dependent azimuthal asymmetries in the pion-induced Drell-Yan (DY) process is reported. We use the CERN SPS 190 GeV/$c$, $\pi^{-}$ beam and a transversely polarized ammonia target. Three azimuthal asymmetries giving access to different transverse-momentum-dependent (TMD) parton distribution functions (PDFs) are extracted using dimuon events with invariant mass between 4.3 GeV/$c^2$ and 8.5 GeV/$c^2$. The observed sign of the Sivers asymmetry is found to be consistent with the fundamental prediction of Quantum Chromodynamics (QCD) that the Sivers TMD PDFs extracted from DY have a sign opposite to the one extracted from semi-inclusive deep-inelastic sc…
Matching factorization theorems with an inverse-error weighting
2018
We propose a new fast method to match factorization theorems applicable in different kinematical regions, such as the transverse-momentum-dependent and the collinear factorization theorems in Quantum Chromodynamics. At variance with well-known approaches relying on their simple addition and subsequent subtraction of double-counted contributions, ours simply builds on their weighting using the theory uncertainties deduced from the factorization theorems themselves. This allows us to estimate the unknown complete matched cross section from an inverse-error-weighted average. The method is simple and provides an evaluation of the theoretical uncertainty of the matched cross section associated w…
Nuclear modification of forward Drell-Yan production at the LHC
2017
Forward Drell-Yan production at high energy can provide important constraints on gluon densities at small $x$, in the saturation regime. In this work we focus on the nuclear modification of this process, which could be measured at the LHC in the near future. For this we employ the color dipole approach, using the optical Glauber model to relate the dipole cross section of a nucleus to the one of a proton. Combining these results with our earlier results for forward $J/\psi$ production, we compute the ratio of the nuclear modification factors of these two processes. This observable was recently suggested as a way to distinguish between initial and final state effects in forward particle prod…
Erratum to: DYTurbo: fast predictions for Drell–Yan processes
2020
The European physical journal / C 80(5), 440 (2020). doi:10.1140/epjc/s10052-020-7972-0
DYTurbo: fast predictions for Drell–Yan processes
2019
The European physical journal / C 80(5), 251 (2020). doi:10.1140/epjc/s10052-020-7757-5
Sivers asymmetry extracted in SIDIS at the hard scales of the Drell-Yan process at COMPASS
2017
Proton transverse-spin azimuthal asymmetries are extracted from the COMPASS 2010 semi-inclusive hadron measurements in deep inelastic muon-nucleon scattering in those four regions of the photon virtuality $Q^2$, which correspond to the four regions of the di-muon mass $\sqrt{Q^2}$ used in the ongoing analysis of the COMPASS Drell-Yan measurements. This allows for a future direct comparison of the nucleon transverse-momentum-dependent parton distribution functions extracted from these two alternative measurements. Various two-dimensional kinematic dependences are presented for the azimuthal asymmetries induced by the Sivers transverse-momentum-dependent parton distribution function. The inte…