Physics at Forward Rapidities -BRAHMS Experiment at RHIC

Abstract. The BRAHMS measurement of particle ratios in p+p collisions at √ s = 62.4 GeV and √ s = 200 GeV is presented as a function of transverse momentum within the pseudorapidity range 0 ≤ η ≤ 3.6. The antiparticle-to-particle baryon and meson ratio at both energies has a similar tendency showing slight dependency on pseudorapidity. The p/π ratio measured in elementary collisions at √ s = 62.4 GeV, η ≈ 3 reaches astounding value of 8-10 at p T ≥ 1.5 GeV/c. Moreover, a remarkable overlap of net-proton dN dy is observed at all energies when viewed in their projectile frame

Physics Revealed at Intermediate p_T

A review is given on the subject of hadron production at intermediate $p_T$ in heavy-ion collisions. The underlying dynamical processes are inferred from interpreting the data in the framework of recombination. Ridge formation with or without triggers is found to play an important role in nearly all observables in that $p_T$ region. Correlation data would be hard to interpret without taking ridges into account. The semi-hard partons that create the ridges may even be able to drive elliptic flow without fast thermalization.Comment: 8 pages, plenary talk given at Quark Matter 2008, Jaipur, Indi

Pion emission from the T2K replica target: method, results and application

The T2K long-baseline neutrino oscillation experiment in Japan needs precise predictions of the initial neutrino flux. The highest precision can be reached based on detailed measurements of hadron emission from the same target as used by T2K exposed to a proton beam of the same kinetic energy of 30 GeV. The corresponding data were recorded in 2007-2010 by the NA61/SHINE experiment at the CERN SPS using a replica of the T2K graphite target. In this paper details of the experiment, data taking, data analysis method and results from the 2007 pilot run are presented. Furthermore, the application of the NA61/SHINE measurements to the predictions of the T2K initial neutrino flux is described and discussed.Comment: updated version as published by NIM

Single Transverse Spin Asymmetries of Identified Charged Hadrons in Polarized p+p Collisions at s\sqrt{s} = 62.4 GeV

The first measurements of $x_F$-dependent single spin asymmetries of identified charged hadrons, $\pi^{\pm}$, $K^{\pm}$, and protons, from transversely polarized proton-proton collisions at 62.4 GeV at RHIC are presented. The measurements extend to high-$x_F$ ($|x_F|\sim 0.6$) in both the forward and backward directions.Large asymmetries are seen in the pion and kaon channels. The asymmetries in inclusive $\pi^{+}$ production, $A_N(\pi^+)$, increase with $x_F$ from 0 to $\sim$0.25 %at $x_F = 0.6$ and $A_N(\pi^{-})$ decrease from 0 to $\sim$$-$0.4. Even though $K^-$ contains no valence quarks, observed asymmetries for $K^-$ unexpectedly show positive values similar to those for $K^+$, increasing with $x_F$, whereas proton asymmetries are consistent with zero over the measured kinematic range. Comparisons of the data with predictions of QCD-based models are presented. The flavor dependent single spin asymmetry measurements of identified hadrons allow for stringent tests of theoretical models of partonic dynamics in the RHIC energy regime.Comment: 4 pages, 5 figures. 36 authors. Published version in PR

The p/π ratio p T -dependence in the RHIC range of baryo-chemical potential

The BRAHMS measurement of proton-to-pion ratios in Au+Au and p+p collisions at √ sNN = 62.4 GeV and √ sNN = 200 GeV is presented as a function of transverse momentum and collision centrality within the pseudorapidity range 0 ≤ η ≤ 3. The baryo-chemical potential, µB, for the indicated data spans from µB ≈ 26 MeV ( . The p/π ratio measured for Au+Au system at √ sNN = 62.4 GeV, η ≈ 3 reaches astounding value of 8-10 at pT ≥ 1.5 GeV/c. For these energy and pseudorapidity interval no centrality dependency of p/π ratio is observed. Moreover, the baryon-to-meson ratio of nucleus-nucleus data are consistent with results obtained for p+p interactions

Measurements of cross sections and charged pion spectra in proton-carbon interactions at 31 GeV/c

Interaction cross sections and charged pion spectra in p+C interactions at 31 GeV/c were measured with the large-acceptance NA61/SHINE spectrometer at the CERN SPS. These data are required to improve predictions of the neutrino flux for the T2K long-baseline neutrino oscillation experiment in Japan. A set of data collected during the first NA61/SHINE run in 2007 with an isotropic graphite target with a thickness of 4% of a nuclear interaction length was used for the analysis. The measured p+C inelastic and production cross sections are 257.2 ± 1.9 ± 8.9 and 229.3 ± 1.9 ± 9.0 mb, respectively. Inclusive production cross sections for negatively and positively charged pions are presented as functions of laboratory momentum in ten intervals of the laboratory polar angle covering the range from 0 up to 420 mrad. The spectra are compared with predictions of several hadron production models. © 2011 American Physical Society

Measurement of production properties of positively charged kaons in proton-carbon interactions at 31 GeV/c

Spectra of positively charged kaons in p+C interactions at 31 GeV/c were measured with the NA61/SHINE spectrometer at the CERN SPS. The analysis is based on the full set of data collected in 2007 with a graphite target with a thickness of 4% of a nuclear interaction length. Interaction cross sections and charged pion spectra were already measured using the same set of data. These new measurements in combination with the published ones are required to improve predictions of the neutrino flux for the T2K long-baseline neutrino oscillation experiment in Japan. In particular, the knowledge of kaon production is crucial for precisely predicting the intrinsic electron neutrino component and the high-energy tail of the T2K beam. The results are presented as a function of laboratory momentum in two intervals of the laboratory polar angle covering the range from 20 to 240 mrad. The kaon spectra are compared with predictions of several hadron production models. Using the published pion results and the new kaon data, the K+/π+ ratios are computed. © 2012 American Physical Society