Spin Physics Experiments at NICA-SPD with polarized proton and deuteron beams

Abstract

Abstract. The brief description of the Letter of Intent proposing primarily to perform measurements of asymmetries of the DY pair production in collisions of non-polarized, longitudinally and transversally polarized protons and deuterons which provide an access to all leading twist collinear and TMD PDFs of quarks and anti-quarks in nucleons.Main parts of the Letter of Intent (LoI) [1], devoted to development of spin program of NICA complex at JINR, are related to the studies of the nucleon structure. The beginning of the nucleon structure story refers to the early 50-ties of the 20th century when in the famous Hofstadter's experiments at SLAC the proton electromagnetic form factor was measured determining thus the proton radius.The naive quark-parton model (QPM) of nucleons, i.e. of the proton and neutron, has been born. Partons share between themselves fractions, x, of the total nucleon momentum. Parton Distribution Functions (PDFs) are universal characteristics of the internal nucleon structure. Now the quark-parton structure of nucleons and respectively the quark-parton model of nucleons are becoming more and more complicated and may even lose the universality property. Measurements of the collinear (integrated over k T ) and Transverse Momentum Dependent (TMD) PDFs, the most of which are not well measured or not discovered yet, are proposed in this LoI.1 The TMD PDFs.The new TMD PDFs can be measured only in the SIDIS or DY processes. In SIDIS, the TMD PDFs can be extracted from the data studying the azimuthal modulations of hadrons which are sensitive to convolution of PDF with the corresponding FF. They include transversity, Sivers, Boer-Mulders, pretzelosity and worm-gear functions. a Speaker; e-mail: teryaev@theor.jinr.ru Physics motivation The Drell-Yan mechanism as the second microscope of the nucleon structure studiesThe Drell-Yan (DY) process of the di-lepton production in high-energy hadron-hadron collisions is playing an important role in the hadron structure studies.Applying the Fourier analysis to the measured asymmetries, one can separate each of all ratios of angular modulations coefficients. This will be the ultimate task of the experiments proposed for SPD. The extraction of different TMD PDFs from those ratios is a task of the global theoretical analysis (a challenge for the theoretical community) since each of the angular coefficients is a result of convolutions of different TMD PDFs in the quark transverse momentum space. For this purpose one needs either to assume a factorization of the transverse momentum dependence for each TMD PDFs, having definite mathematic form (usually Gaussian) with some parameters to be fitted, or to transfer functions to impact parameter representation space and to use the Bessel weighted TMD PDFs.The full set of asymmetries gives the access to all eight leading twist TMD PDFs. However, sometimes one can work with integrated asymmetries. Integrated asymmetries are useful for the express analysis of data and checks of expected relations between asymmetries. They ...

Elliptic flow in ultrarelativistic collisions with light polarized nuclei

“…For the deuteron, the experimentally accessible polarization is −1.5 P zz 0.7 [38,39]. Similar formulas can be provided for higher spin states.…”

On the Possibility to Study Antiproton Production at the SPD Detector at NICA Collider for Dark Matter Search in Astrophysical Experiments

“…The first priority program of NICA is the study of properties of dense baryonic matter in heavy ion collisions at the Multi-Purpose Detector (MPD) [24]. In parallel, the operation of the NICA collider with polarized proton and deuteron beams for spin physics studies at the Spin Physics Detector (SPD) is also under consideration [25]. The planned kinetic energy of polarized proton beam is from 5 GeV to about 12.6 GeV while the polarized deuteron beam energy is expected to range from 4 GeV to 11.8 GeV.…”

SPD — the Spin Physics Project with Polarized Proton and Deuteron Beams at the NICA Collider

“…The Spin Physics Detector is planned to be a universal detector for a wide range of physics tasks. More detailed information about the SPD project could be found in the Letter of Intent [1] and the preliminary version of the Conceptual Design Report [21].…”

“…• worm-gear functions: A cos(2φ h ) U L , correlation between the longitudinal polarization of the nucleon (longitudinal spin) and the transverse momentum of quarks. All mentioned PDFs are proposed to be measured with SPD [1]. At the twist-3 approximation there are already 16 TMD PDFs containing the information on the nucleon structure.…”