Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userMeasurement of zero degree inclusive photon energy spectra for $sqrt{s}=$ 900 GeV proton-proton collisions at LHC
150
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
The inclusive photon energy spectra measured by the Large Hadron Collider forward (LHCf) experiment in the very forward region of LHC proton-proton collisions at $sqrt{s}=$ 900 GeV are reported. The results from the analysis of 0.30 $mathrm{nb^{-1}}$ of data collected in May 2010 in the two pseudorapidity regions of $eta > 10.15$ and $8.77 < eta < 9.46$ are compared with the predictions of the hadronic interaction models DPMJET 3.04, EPOS 1.99, PYTHIA 8.145, QGSJET I -.1em I-03 and SIBYLL 2.1, which are widely used in ultra-high-energy cosmic-ray experiments. EPOS 1.99 and SYBILL 2.1 show a reasonable agreement with the spectral shape of the experimental data, whereas they predict lower cross-sections than the data. The other models, DPMJET 3.04, QGSJET I -.1em I-03 and PYTHIA 8.145, are in good agreement with the data below 300 GeV but predict harder energy spectra than the data above 300 GeV. The results of these comparisons exhibited features similar to those for the previously reported data for $sqrt{s}=$ 7 TeV collisions.
rate research
Read More
In early 2010, the Large Hadron Collider forward (LHCf) experiment measured very forward neutral particle spectra in LHC proton-proton collisions. From a limited data set taken under the best beam conditions (low beam-gas background and low occurance of pile-up events), the single photon spectra at sqrt(s)=7TeV and pseudo-rapidity (eta) ranges from 8.81 to 8.99 and from 10.94 to infinity were obtained for the first time and are reported in this paper. The spectra from two independent LHCf detectors are consistent with one another and serve as a cross check of the data. The photon spectra are also compared with the predictions of several hadron interaction models that are used extensively for modeling ultra high energy cosmic ray showers. Despite conservative estimates for the systematic errors, none of the models agree perfectly with the measurements. A notable difference is found between the data and the DPMJET 3.04 and PYTHIA 8.145 hadron interaction models above 2TeV where the models predict higher photon yield than the data. The QGSJET II-03 model predicts overall lower photon yield than the data, especially above 2TeV in the rapidity range 8.81<eta<8.99.
The inclusive production rate of neutral pions in the rapidity range greater than $y=8.9$ has been measured by the Large Hadron Collider forward (LHCf) experiment during LHC $sqrt{s}=7$,TeV proton-proton collision operation in early 2010. This paper presents the transverse momentum spectra of the neutral pions. The spectra from two independent LHCf detectors are consistent with each other and serve as a cross check of the data. The transverse momentum spectra are also compared with the predictions of several hadronic interaction models that are often used for high energy particle physics and for modeling ultra-high-energy cosmic-ray showers.
We report a new high-precision measurement of the mid-rapidity inclusive jet longitudinal double-spin asymmetry, $A_{LL}$, in polarized $pp$ collisions at center-of-mass energy $sqrt{s}=200$ GeV. The STAR data place stringent constraints on polarized parton distribution functions extracted at next-to-leading order from global analyses of inclusive deep inelastic scattering (DIS), semi-inclusive DIS, and RHIC $pp$ data. The measured asymmetries provide evidence for positive gluon polarization in the Bjorken-$x$ region $x>0.05$.
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.
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 $x > 0.05$.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
