Recent Mid-Rapidity ALLπ0 Measurements in Longitudinally Polarized Proton-Proton Collision at s = 510 GeV with PHENIX Experiment

2016 ◽  
Vol 40 ◽  
pp. 1660022
Author(s):  
Inseok Yoon
Keyword(s):  
Center Of Mass ◽  
Heavy Ion ◽  
Proton Collision ◽  
Relativistic Heavy Ion Collider ◽  
Proton Proton ◽  
Center Of Mass Energy ◽  
Helicity Distribution ◽  
Statistical Precision ◽  
Polarized Proton ◽  
Energy Formula

It is one of the important purposes of relativistic heavy ion collider (RHIC) longitudinally polarized proton program to constrain the gluon helicity distribution ([Formula: see text]) to the proton by measuring the double helicity asymmetries ([Formula: see text]) via various probes such as [Formula: see text] ([Formula: see text]). The measurement at center of mass energy, [Formula: see text] GeV has been successfully finished and published. To explore lower x region, where dominant uncertainty remains, new measurements were carried out at an increased [Formula: see text] GeV. At this increased energy central [Formula: see text] measurements can reach a lower x range of [Formula: see text], while the previous can reach x range, [Formula: see text]. Also the statistical precision at the same transverse momentum ([Formula: see text]) is substantially improved due to accumulating about 10 times as much luminosity. Preliminary results of [Formula: see text] are presented. Larger asymmetry is observed at [Formula: see text] GeV than at [Formula: see text] GeV at the same [Formula: see text] which is expected due to evolution.

scholarly journals HADRON SPECTRA IN p+p COLLISIONS AT RHIC AND LHC ENERGIES

2013 ◽  
Vol 28 (16) ◽  
pp. 1350066 ◽  
Author(s):  
P. K. KHANDAI ◽  
P. SETT ◽  
P. SHUKLA ◽  
V. SINGH
Keyword(s):  
Hadron Collider ◽  
Center Of Mass ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collider ◽  
Systematic Analysis ◽  
Center Of Mass Energy ◽  
Hadron Spectra ◽  
200 Gev ◽  
Energy Formula ◽  
Two Parameters

We present the systematic analysis of transverse momentum (pT) spectra of identified hadrons in p+p collisions at Relativistic Heavy Ion Collider ([Formula: see text] and 200 GeV) and at Large Hadron Collider (LHC) energies ([Formula: see text], 2.76 and 7.0 TeV) using phenomenological fit functions. We review various forms of Hagedorn and Tsallis distributions and show their equivalence. We use Tsallis distribution which successfully describes the spectra in p+p collisions using two parameters, Tsallis temperature T which governs the soft bulk spectra and power n which determines the initial production in partonic collisions. We obtain these parameters for pions, kaons and protons as a function of center-of-mass energy [Formula: see text]. It is found that the parameter T has a weak but decreasing trend with increasing [Formula: see text]. The parameter n decreases with increasing [Formula: see text] which shows that production of hadrons at higher energies are increasingly dominated by point like qq scatterings. Another important observation is with increasing [Formula: see text], the separation between the powers for protons and pions narrows down hinting that the baryons and mesons are governed by same production process as one moves to the highest LHC energy.

scholarly journals ELECTROWEAK CORRECTIONS TO THE NEUTRALINO PAIR PRODUCTION AT CERN LHC

2013 ◽  
Vol 28 (17) ◽  
pp. 1350077 ◽  
Author(s):  
A. I. AHMADOV ◽  
M. DEMIRCI
Keyword(s):  
Pair Production ◽  
Cross Sections ◽  
Center Of Mass ◽  
Percent Level ◽  
Proton Collision ◽  
Mass Energy ◽  
Proton Proton ◽  
Center Of Mass Energy ◽  
Energy Formula ◽  
Proton Proton Collision

We apply the leading and subleading electroweak (EW) corrections to the Drell–Yan process of the neutralino pair production at proton–proton collision, in order to calculate the effects of these corrections on the neutralino pair production at the LHC. We provide an analysis of the dependence of the Born cross-sections for [Formula: see text] and the EW corrections to this process, on the center-of-mass energy [Formula: see text], on the M2–μ mass plane and on the squark mass for the three different scenarios. The numerical results show that the relative correction can be reached to the few tens of percent level as the increment of the center-of-mass energy, and the evaluation of EW corrections is a crucial task for all accurate measurements of the neutralino pair production processes.

HYDJET SIMULATIONS OF ELLIPTIC FLOW IN HEAVY ION COLLISIONS AT THE LHC

2007 ◽  
Vol 16 (07n08) ◽  
pp. 1917-1922
Author(s):  
D. KROFCHECK ◽  
R. MAK ◽  
P. ALLFREY
Keyword(s):  
Hadron Collider ◽  
Center Of Mass ◽  
Elliptic Flow ◽  
Heavy Ion ◽  
Event Generator ◽  
Simulation Tool ◽  
Mass Energy ◽  
Relativistic Heavy Ion Collider ◽  
Center Of Mass Energy ◽  
Ion Collisions

At the Relativistic Heavy Ion Collider (RHIC) elliptic flow signals (v2) appear to be stronger than those measured at lower center-of-mass energies. With the beginning of heavy ion beams at the Large Hadron Collider (LHC) it is important to have a reliable tool for simulating v2 at the LHC Pb – Pb center-of-mass energy of 5.5 A TeV. In this work we used the heavy ion simulation tool HYDJET to study elliptic flow at the event generator level. The generator level elliptic flow v2 for Pb – Pb collisions was two-particle and four-particle cumulants.

scholarly journals Hadron Spectra Parameters within the Non-Extensive Approach

Universe ◽  
2019 ◽  
Vol 5 (5) ◽  
pp. 122 ◽  
Author(s):  
Keming Shen ◽  
Gergely Gábor Barnaföldi ◽  
Tamás Sándor Biró
Keyword(s):  
High Energy Physics ◽  
Center Of Mass ◽  
Heavy Ion ◽  
High Energy ◽  
Proton Proton ◽  
Center Of Mass Energy ◽  
Ion Collisions ◽  
Hadron Spectra ◽  
Hadron Mass ◽  
Energy Scaling

We investigate how the non-extensive approach works in high-energy physics. Transverse momentum ( p T ) spectra of several hadrons are fitted by various non-extensive momentum distributions and by the Boltzmann–Gibbs statistics. It is shown that some non-extensive distributions can be transferred one into another. We find explicit hadron mass and center-of-mass energy scaling both in the temperature and in the non-extensive parameter, q, in proton–proton and heavy-ion collisions. We find that the temperature depends linearly, but the Tsallis q follows a logarithmic dependence on the collision energy in proton–proton collisions. In the nucleus–nucleus collisions, on the other hand, T and q correlate linearly, as was predicted in our previous work.

scholarly journals Azimuthal separation in nearly back-to-back jet topologies in inclusive 2- and 3-jet events in $${\text {p}} {\text {p}} $$ collisions at $$\sqrt{s}=13\,\text {Te}\text {V} $$

2019 ◽  
Vol 79 (9) ◽  
Author(s):  
A. M. Sirunyan ◽  
◽  
A. Tumasyan ◽  
W. Adam ◽  
F. Ambrogi ◽  
...  
Keyword(s):  
Center Of Mass ◽  
Proton Collision ◽  
Leading Order ◽  
Proton Proton ◽  
Perturbative Quantum Chromodynamics ◽  
Center Of Mass Energy ◽  
Theoretical Predictions ◽  
Proton Proton Collision ◽  
Perturbative Quantum ◽  
Two Jets

Abstract A measurement for inclusive 2- and 3-jet events of the azimuthal correlation between the two jets with the largest transverse momenta, $$\varDelta \phi _{12}$$Δϕ12, is presented. The measurement considers events where the two leading jets are nearly collinear (“back-to-back”) in the transverse plane and is performed for several ranges of the leading jet transverse momentum. Proton-proton collision data collected with the CMS experiment at a center-of-mass energy of $$13\,\text {Te}\text {V} $$13Te and corresponding to an integrated luminosity of $$35.9{\,\text {fb}^{-1}} $$35.9fb-1 are used. Predictions based on calculations using matrix elements at leading-order and next-to-leading-order accuracy in perturbative quantum chromodynamics supplemented with leading-log parton showers and hadronization are generally in agreement with the measurements. Discrepancies between the measurement and theoretical predictions are as large as 15%, mainly in the region $$177^\circ< \varDelta \phi _{12} < 180^\circ $$177∘<Δϕ12<180∘. The 2- and 3-jet measurements are not simultaneously described by any of models.

scholarly journals Comparing Multicomponent Erlang Distribution and Lévy Distribution of Particle Transverse Momentums

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Hua-Rong Wei ◽  
Ya-Hui Chen ◽  
Li-Na Gao ◽  
Fu-Hu Liu
Keyword(s):  
Hadron Collider ◽  
Center Of Mass ◽  
Heavy Ion ◽  
Erlang Distribution ◽  
Relativistic Heavy Ion Collider ◽  
Final State ◽  
Heavy Particles ◽  
Proton Proton ◽  
Lévy Distribution ◽  
Levy Distribution

The transverse momentum spectrums of final-state products produced in nucleus-nucleus and proton-proton collisions at different center-of-mass energies are analyzed by using a multicomponent Erlang distribution and the Lévy distribution. The results calculated by the two models are found in most cases to be in agreement with experimental data from the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). The multicomponent Erlang distribution that resulted from a multisource thermal model seems to give a better description as compared with the Lévy distribution. The temperature parameters of interacting system corresponding to different types of final-state products are obtained. Light particles correspond to a low temperature emission, and heavy particles correspond to a high temperature emission. Extracted temperature from central collisions is higher than that from peripheral collisions.

scholarly journals JET RESULTS AND JET RECONSTRUCTION TECHNIQUES IN p+p AND THEIR PROSPECTS IN HEAVY-ION COLLISIONS IN ATLAS

2011 ◽  
Vol 20 (07) ◽  
pp. 1545-1550
Author(s):  
◽  
MARTIN SPOUSTA
Keyword(s):  
Cross Sections ◽  
Heavy Ion Collisions ◽  
Center Of Mass ◽  
Heavy Ion ◽  
Proton Proton ◽  
Center Of Mass Energy ◽  
Ion Collisions ◽  
Expected Performance ◽  
Jet Shapes ◽  
Jet Cross Sections

We present the measurement of jet production performed with the ATLAS detector in proton-proton collisions at center-of-mass energy of 7 TeV, using an integrated luminosity of 17 nb−1. We show the inclusive jet cross sections and jet shapes. The expected performance and strategy for the jet reconstruction in heavy ion collisions is also discussed.

scholarly journals Future Circular Colliders

2019 ◽  
Vol 69 (1) ◽  
pp. 389-415 ◽  
Author(s):  
M. Benedikt ◽  
A. Blondel ◽  
P. Janot ◽  
M. Klein ◽  
M. Mangano ◽  
...  
Keyword(s):  
Particle Physics ◽  
Hadron Collider ◽  
Center Of Mass ◽  
Heavy Ion ◽  
New Physics ◽  
Proton Proton ◽  
Proton Collisions ◽  
Center Of Mass Energy ◽  
Physics Program ◽  
Electron Positron

After 10 years of physics at the Large Hadron Collider (LHC), the particle physics landscape has greatly evolved. Today, a staged Future Circular Collider (FCC), consisting of a luminosity-frontier highest-energy electron–positron collider (FCC-ee) followed by an energy-frontier hadron collider (FCC-hh), promises the most far-reaching physics program for the post-LHC era. FCC-ee will be a precision instrument used to study the Z, W, Higgs, and top particles, and will offer unprecedented sensitivity to signs of new physics. Most of the FCC-ee infrastructure could be reused for FCC-hh, which will provide proton–proton collisions at a center-of-mass energy of 100 TeV and could directly produce new particles with masses of up to several tens of TeV. This collider will also measure the Higgs self-coupling and explore the dynamics of electroweak symmetry breaking. Thermal dark matter candidates will be either discovered or conclusively ruled out by FCC-hh. Heavy-ion and electron–proton collisions (FCC-eh) will further contribute to the breadth of the overall FCC program. The integrated FCC infrastructure will serve the particle physics community through the end of the twenty-first century. This review combines key contents from the first three volumes of the FCC Conceptual Design Report.

scholarly journals Searches for low-mass dimuon resonances

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
R. Aaij ◽  
◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Cross Sections ◽  
Center Of Mass ◽  
Mass Range ◽  
Higgs Doublet ◽  
Proton Collision ◽  
Proton Proton ◽  
Center Of Mass Energy ◽  
Lhcb Detector ◽  
Low Mass ◽  
Proton Proton Collision

Abstract Searches are performed for a low-mass dimuon resonance, X, produced in proton-proton collisions at a center-of-mass energy of 13 TeV, using a data sample corresponding to an integrated luminosity of 5.1 fb−1 and collected with the LHCb detector. The X bosons can either decay promptly or displaced from the proton-proton collision, where in both cases the requirements placed on the event and the assumptions made about the production mechanisms are kept as minimal as possible. The searches for promptly decaying X bosons explore the mass range from near the dimuon threshold up to 60 GeV, with nonnegligible X widths considered above 20 GeV. The searches for displaced X → μ+μ− decays consider masses up to 3 GeV. None of the searches finds evidence for a signal and 90% confidence-level exclusion limits are placed on the X → μ+μ− cross sections, each with minimal model dependence. In addition, these results are used to place world-leading constraints on GeV-scale bosons in the two-Higgs-doublet and hidden-valley scenarios.

scholarly journals Gluon polarization measurements from longitudinally polarized proton-proton collisions at STAR

2020 ◽  
Vol 1643 (1) ◽  
pp. 012184
Author(s):  
Zilong Chang
Keyword(s):  
Spin Asymmetry ◽  
Center Of Mass ◽  
Heavy Ion ◽  
Proton Spin ◽  
Gluon Polarization ◽  
Relativistic Heavy Ion Collider ◽  
Center Of Mass Energy ◽  
Double Spin ◽  
200 Gev ◽  
Inclusive Jet

Abstract The gluon polarization contribution to the proton spin is an integral part to solve the longstanding proton spin puzzle. At the Relativistic Heavy Ion Collider (RHIC), the STAR experiment has measured jets produced in mid-pseudo-rapidity, |η| < 1.0, and full azimuth, ϕ, from longitudinally polarized pp collisions to study the gluon polarization in the proton. At center of mass energies s = 200 and 510 GeV, jet production is dominated by hard QCD scattering processes such as gluon-gluon (gg) and quark-gluon (qg), thus making the longitudinal double-spin asymmetry (ALL ) sensitive to the gluon polarization. Early STAR inclusive jet ALL results at s = 200 GeV provided the first evidence of the non-zero gluon polarization at momentum fraction x > 0.05. The higher center of mass energy s = 510 GeV allows to explore the gluon polarization as low as x ∼ 0.015. In this talk we will present the recent STAR inclusive jet and dijet ALL results at s = 510 GeV, and discuss the relevant new analysis techniques for the estimation of trigger bias and reconstruction uncertainty, the underlying event correction on the jet energy and its effect on jet ALL . Dijet results are shown for different topologies in regions of pseudo-rapidity, effectively scanning the x-dependence of the gluon polarization.

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