## 2014 UGRC - Full Schedule

#### Title

Exploring Gluon Polarization in the Proton with STAR Jet Data and the NNPDF Polarized Parton Distributions

Physics

Physics

Gagliardi, Carl

DOE, NSF-REU

#### Abstract

The NNPDF Polarized Parton Distribution Functions (PDF) are a PDF set made using a neural network technique rather than using traditional functional forms. The NNPDF polarized parton distribution includes one hundred different fits, or replicas, that are all considered equally probable. The NNPDF replicas were used to calculate the longitudinal double-spin asymmetry, $A_{LL}$, for inclusive jet production at $\sqrt{s} = \text{200 GeV}$. The calculations were compared to STAR inclusive jet $A_{LL}$ results from 2006 and 2009, and the $\chi^{2}$ was determined for each replica. The $\chi^{2}$ values were used in a reweighting procedure, which the NNPDF group developed, for the inclusion of new data into an existing PDF fit. After the reweighting, the polarization of the gluon is examined. The STAR data provide significant constraining power on the gluon polarization, compared to the unweighted NNPDF set.

#### Biography

Andrew Cudd is a senior in Physics, graduating this May with his B.S. in Physics with Minors in Mathematics and Computer Engineering. He is planning on going to graduate school in physics to earn his doctorate in physics, most likely nuclear or high energy physics. The work being presented was performed at the Texas A&M Cyclotron Institute during the summer of 2013 through the NSF Research Experience for Undergraduates program.

Sciences

#### Presentation Type

Poster Presentation

Poster

#### Location

Upper Atrium/Hall

#### Presentation Date

16 Apr 2014, 9:00 am - 11:45 am

Research Advisor: Carl Gagliardi (Texas A&M)

#### Share

COinS

Apr 16th, 9:00 AM Apr 16th, 11:45 AM

Exploring Gluon Polarization in the Proton with STAR Jet Data and the NNPDF Polarized Parton Distributions

Upper Atrium/Hall

The NNPDF Polarized Parton Distribution Functions (PDF) are a PDF set made using a neural network technique rather than using traditional functional forms. The NNPDF polarized parton distribution includes one hundred different fits, or replicas, that are all considered equally probable. The NNPDF replicas were used to calculate the longitudinal double-spin asymmetry, $A_{LL}$, for inclusive jet production at $\sqrt{s} = \text{200 GeV}$. The calculations were compared to STAR inclusive jet $A_{LL}$ results from 2006 and 2009, and the $\chi^{2}$ was determined for each replica. The $\chi^{2}$ values were used in a reweighting procedure, which the NNPDF group developed, for the inclusion of new data into an existing PDF fit. After the reweighting, the polarization of the gluon is examined. The STAR data provide significant constraining power on the gluon polarization, compared to the unweighted NNPDF set.