Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userSingle Spin Asymmetry $A_N$ in Polarized Proton-Proton Elastic Scattering at $sqrt{s}=200$ GeV
152
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We report a high precision measurement of the transverse single spin asymmetry $A_N$ at the center of mass energy $sqrt{s}=200$ GeV in elastic proton-proton scattering by the STAR experiment at RHIC. The $A_N$ was measured in the four-momentum transfer squared $t$ range $0.003 leqslant |t| leqslant 0.035$ $GeVcSq$, the region of a significant interference between the electromagnetic and hadronic scattering amplitudes. The measured values of $A_N$ and its $t$-dependence are consistent with a vanishing hadronic spin-flip amplitude, thus providing strong constraints on the ratio of the single spin-flip to the non-flip amplitudes. Since the hadronic amplitude is dominated by the Pomeron amplitude at this $sqrt{s}$, we conclude that this measurement addresses the question about the presence of a hadronic spin flip due to the Pomeron exchange in polarized proton-proton elastic scattering.
rate research
Read More
The differential cross section and spin asymmetries for neutral pions produced within the intermediate pseudorapidity range 0.8 < {eta} < 2.0 in polarized proton-proton collisions at sqrt{s} = 200 GeV are presented. Neutral pions were detected using the endcap electromagnetic calorimeter in the STAR detector at RHIC. The cross section was measured over a transverse momentum range of 5 < p_T < 16 GeV/c and is found to be within the scale uncertainty of a next-to-leading order perturbative QCD calculation. The longitudinal double-spin asymmetry, A_LL, is measured in the same pseudorapidity range. This quantity is sensitive to the gluonic contribution to the proton spin, {Delta}g(x), at low Bjorken-x (down to x approx 0.01), where it is less constrained by measurements at central pseudorapidity. The measured A_LL is consistent with model predictions. The parity-violating asymmetry, A_L, is also measured and found to be consistent with zero. The transverse single-spin asymmetry, A_N, is measured within a previously unexplored kinematic range in Feynman-x and p_T. Such measurements may aid our understanding of the on-set and kinematic dependence of the large asymmetries observed at more forward pseudorapidity ({eta} approx 3) and their underlying mechanisms. The A_N results presented are consistent with a twist-3 model prediction of a small asymmetry within the present kinematic range.
Transverse single spin asymmetry, $A_{N}$, of very forward $pi^{0}$ production from polarized $p + p$ collisions provides new information toward an understanding of its production mechanism. $A_{N}$ of forward $pi^{0}$ in the pseudorapidity region of $3 < eta < 4$ has been described by the partonic structure of the proton in the perturbative QCD framework. However, recent data indicates a potential contribution from not only partonic but also diffractive interactions. In order to provide a new insight on the origin of the $A_{N}$, we measured the very forward $pi^{0}$ production in the pseudorapidity region of $6 < eta$ from $sqrt{s}$ = 510 GeV polarized $p + p$ collisions at RHIC in 2017. We report our measurement of the very forward $pi^{0}$ over the transverse momentum range of $0 < p_{T} < 1$ GeV/$c$ and the preliminary result.
We report high-precision measurements of the longitudinal double-spin asymmetry, $A_{LL}$, for midrapidity inclusive jet and dijet production in polarized $pp$ collisions at a center-of-mass energy of $sqrt{s}=200,mathrm{GeV}$. The new inclusive jet data are sensitive to the gluon helicity distribution, $Delta g(x,Q^2)$, for gluon momentum fractions in the range from $x simeq 0.05$ to $x simeq 0.5$, while the new dijet data provide further constraints on the $x$ dependence of $Delta g(x,Q^2)$. The results are in good agreement with previous measurements at $sqrt{s}=200,mathrm{GeV}$ and with recent theoretical evaluations of prior world data. Our new results have better precision and thus strengthen the evidence that $Delta g(x,Q^2)$ is positive for $x > 0.05$.
These proceedings show the preliminary results of the dijet cross sections and the dijet longitudinal double spin asymmetries A_LL in polarized proton-proton collisions at sqrt{s} = 200 GeV at the mid-rapidity |eta| < 0.8. The integrated luminosity of 5.39 pb^{-1} collected during RHIC Run-6 was used in the measurements. The preliminary results are presented as functions of the dijet invariant mass M_jj. The dijet cross sections are in agreement with next-to-leading-order pQCD predictions. The A_LL is compared with theoretical predictions based on various parameterizations of polarized parton distributions of the proton. Projected precision of data analyzed to date from Run-9 are shown.
We report results on the total and elastic cross sections in proton-proton collisions at $sqrt{s}=200$ GeV obtained with the Roman Pot setup of the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The elastic differential cross section was measured in the squared four-momentum transfer range $0.045 leq -t leq 0.135$ GeV$^2$. The value of the exponential slope parameter $B$ of the elastic differential cross section $dsigma/dt sim e^{-Bt}$ in the measured $-t$ range was found to be $B = 14.32 pm 0.09 (stat.)^{scriptstyle +0.13}_{scriptstyle -0.28} (syst.)$ GeV$^{-2}$. The total cross section $sigma_{tot}$, obtained from extrapolation of the $dsigma/dt$ to the optical point at $-t = 0$, is $sigma_{tot} = 54.67 pm 0.21 (stat.) ^{scriptstyle +1.28}_{scriptstyle -1.38} (syst.)$ mb. We also present the values of the elastic cross section $sigma_{el} = 10.85 pm 0.03 (stat.) ^{scriptstyle +0.49}_{scriptstyle -0.41}(syst.)$ mb, the elastic cross section integrated within the STAR $t$-range $sigma^{det}_{el} = 4.05 pm 0.01 (stat.) ^{scriptstyle+0.18}_{scriptstyle -0.17}(syst.)$ mb, and the inelastic cross section $sigma_{inel} = 43.82 pm 0.21 (stat.) ^{scriptstyle +1.37}_{scriptstyle -1.44} (syst.)$ mb. The results are compared with the world data.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
