Probing Gluons at the Spin Physics Detector

The Spin Physics Detector (SPD) at the Nuclotron based Ion Collider fAcility (NICA) is a multi-purpose experiment designed to study nucleon spin structure in the three dimensions. With capabilities to collide polarized protons and deuterons with center of mass energy up to 27 GeV and luminosity up to $10^{32} \rm cm^{-2} \ s^{-1}$ for protons (an order of magnitude less for deuterons), the experiment will allow measurements of cross-sections and spin asymmetries of hadronic processes sensitive to the unpolarized and various polarized (helicity, Sivers, Boer-Mulders) gluon distributions inside the nucleons. Results from the SPD will be complementary to the present high energy spin experiments at the RHIC facility or future experiments like the EIC (at BNL) and AFTER (at LHC). SPD will provide data in moderate and large Bjorken-x for much improved global analyses of spin structures of the basic building blocks of Nature. With polarized deuteron collisions, SPD will be the unique laboratory for probing tensor polarized gluon distributions. In addition, there are also possibilities of colliding other light nuclei like Carbon at reduced collision energy and luminosity at the first stage of the experiment.Comment: Accepted for publication in MDPI Physics special issue `From Heavy Ions to Astroparticle Physics

Dynamics of Hot QCD Matter -- Current Status and Developments

The discovery and characterization of hot and dense QCD matter, known as Quark Gluon Plasma (QGP), remains the most international collaborative effort and synergy between theorists and experimentalists in modern nuclear physics to date. The experimentalists around the world not only collect an unprecedented amount of data in heavy-ion collisions, at Relativistic Heavy Ion Collider (RHIC), at Brookhaven National Laboratory (BNL) in New York, USA, and the Large Hadron Collider (LHC), at CERN in Geneva, Switzerland but also analyze these data to unravel the mystery of this new phase of matter that filled a few microseconds old universe, just after the Big Bang. In the meantime, advancements in theoretical works and computing capability extend our wisdom about the hot-dense QCD matter and its dynamics through mathematical equations. The exchange of ideas between experimentalists and theoreticians is crucial for the progress of our knowledge. The motivation of this first conference named "HOT QCD Matter 2022" is to bring the community together to have a discourse on this topic. In this article, there are 36 sections discussing various topics in the field of relativistic heavy-ion collisions and related phenomena that cover a snapshot of the current experimental observations and theoretical progress. This article begins with the theoretical overview of relativistic spin-hydrodynamics in the presence of the external magnetic field, followed by the Lattice QCD results on heavy quarks in QGP, and finally, it ends with an overview of experiment results.Comment: Compilation of the contributions (148 pages) as presented in the `Hot QCD Matter 2022 conference', held from May 12 to 14, 2022, jointly organized by IIT Goa & Goa University, Goa, Indi

Understanding hard interaction in QCD and the search for the gluon spin contribution to the spin of the proton

In the following discourse unpolarized cross sections and double helicity asymmetries of single inclusive positive and negative charged hadrons at mid-rapidity from p + p collisions at [special characters omitted] = 62.4 GeV are presented. Measurements for the transverse momentum range 1.0 \u3c pT \u3c 4.5 GeV/c are done with PHENIX detector at Relativistic Heavy-Ion Collider (RHIC) and are consistent with calculations based on perturbative quantum chromodynamics (pQCD) at next-to-leading order (NLO) in the strong coupling constant, α s. Resummed pQCD calculations including terms with next-to-leading log (NLL) accuracy, yielding reduced theoretical uncertainties, also agree with the data. The double helicity asymmetry, sensitive at leading order to the gluon polarization in a momentum fraction range of 0.05 [special characters omitted] xgluon [special characters omitted] 0.2, is consistent with recent global parameterizations disfavoring large gluon polarization

Session C1: APS, AAPT, and SPS Poster Session - Understanding Hard Interactions in QCD and the Gluon Spin Contribution to the Spin of the Proton

We investigate hard interaction in QCD through the measurement of cross sections of mid-rapidity production of non-identified charged hadrons from $p+p$ collisions at $\sqrt{s} = 62.4$ GeV/$c$. Measurements are made in the transverse momentum range from 0.5 GeV/$c$ to 4.5 GeV/$c$ by the PHENIX collaboration at RHIC. The cross section results are consistent with predictions based on QCD calculations of next-to-leading order (NLO) accuracy and shows better agreement with next-to-leading log QCD predictions. The double helicity asymmetry measurements of mid-rapidity non-identified charged hadrons in the stipulated transverse momentum range are sensitive at leading order to the polarization of gluons in a momentum fraction range $0.06 \leq x_{gluon} \leq 0.3$

Poverty and Fertility - An Instrumental Variables Analysis on Indian Micro Data

The gender of the first two children is used as a natural experiment to estimate the causal effect of fertility on poverty of rural nucleus households in India. In India, male children are viewed as a better source of insurance and support to the family in old age. Thus, having two girls can proxy an exogenous increase in fertility. Using household micro data from the 1993-94 Indian Quinquennial Survey (5th wave), estimation results indicate that fertility significantly positively affects poverty, but that the effect is halved when endogeneity is allowed for. Also, declining fertility accounts for almost a third of the poverty reduction in rural India between 1987/88 and 1993/1994.Poverty; Fertility; Endogeneity; Natural experiment; Instrumental variables

Fertility and the household's economic status: A natural experiment using Indian micro data

We model fertility as endogenous to the family's economic status because poor households choose to have large families in the absence of adequate social insurance. Because of a strong son preference in India, having two girls first can proxy an exogenous increase in fertility, and is therefore a good instrument for fertility in determining poverty of rural households. The 1993-1994 Indian Quinquennial Survey data shows that even though poverty rates are comparable, 74 per cent of two-girl families have a third child compared to 63 per cent of other families. Fertility significantly positively affects poverty when treated as exogenous, but vanishes once endogenised. These results are robust to omitting states with skewed sex ratios and to proxying economic status by expenditures.