Measurement of charged pions in 12C + 12C collisions at 1A GeV and 2A GeV with HADES
The HADES Collaboration, G. Agakishiev, C. Agodi, A. Balanda, G. Bellia, D. Belver, A. Belyaev, J. Bielcik, A. Blanco, A. Bortolotti, J. L. Boyard, P. Braun-Mun… 展开作者
The HADES Collaboration, G. Agakishiev, C. Agodi, A. Balanda, G. Bellia, D. Belver, A. Belyaev, J. Bielcik, A. Blanco, A. Bortolotti, J. L. Boyard, P. Braun-Munzinger, P. Cabanelas, S. Chernenko, T. Christ, R. Coniglione, M. Destefanis, J. Diaz, F. Dohrmann, I. Duran, A. Dybczak, T. Eberl, L. Fabbietti, O. Fateev, R. Ferreira-Marques, P. Finocchiaro, P. Fonte, J. Friese, I. Froehlich, T. Galatyuk, J. A. Garzon, R. Gernhaeuser, A. Gil, C. Gilardi, M. Golubeva, D. Gonzalez-Diaz, E. Grosse, F. Guber, M. Heilmann, T. Heinz, T. Hennino, R. Holzmann, A. Ierusalimov, I. Iori, A. Ivashkin, M. Jurkovic, B. Kaempfer, K. Kanaki, T. Karavicheva, D. Kirschner, I. Koenig, W. Koenig, B. W. Kolb, R. Kotte, A. Kozuch, A. Krasa, F. Krizek, R. Kruecken, W. Kuehn, A. Kugler, A. Kurepin, J. Lamas-Valverde, S. Lang, J. S. Lange, K. Lapidus, L. Lopes, M. Lorenz, L. Maier, C. Maiolino, A. Mangiarotti, J. Marin, J. Markert, V. Metag, B. Michalska, J. Michel, E. Moriniere, J. Mousa, M. Muench, C. Muentz, L. Naumann, R. Novotny, J. Otwinowski, Y. C. Pachmayer, M. Palka, Y. Parpottas, V. Pechenov, O. Pechenova, T. Perez Cavalcanti, P. Piattelli, J. Pietraszko, V. Pospisil, W. Przygoda, B. Ramstein, A. Reshetin, M. Roy-Stephan, A. Rustamov, A. Sadovsky, B. Sailer, P. Salabura, P. Sapienza, A. Schmah, C. Schroeder, E. Schwab, R. S. Simon, Yu. G. Sobolev, S. Spataro, B. Spruck, H. Stroebele, J. Stroth, C. Sturm, M. Sudol, A. Tarantola, K. Teilab, P. Tlusty, M. Traxler, R. Trebacz, H. Tsertos, V. Wagner, M. Weber, M. Wisniowski, T. Wojcik, J. Wuestenfeld, S. Yurevich, Y. Zanevsky, P. Zhou, P. Zumbruch
备注：
15 pages, 13 figures, v2 - the text unchanged, only full author list added to METADATA (in v1 only the first author and collaboration name), reference to published paper added
本文报道了在1AGeV和2AGeV的入射束流能量下，利用GSI的HADES谱仪研究12 C +12 C碰撞中带电π介子产生的结果。HADES程序的主要重点是来自碰撞早期阶段的双电子信号。然而，在这里，我们讨论的数据相对于带电强子的发射，特别是生产π +介子，这是与中性π介子代表占主导地位的贡献的双电子产量。我们首次对~（12）C +~（12）C碰撞系统的π ~+介子分布进行了大角度范围的测量，测量范围覆盖了相当大的快度区间。的π介子产率，横向质量和角分布进行了比较，在一个运输模型内完成的计算，以及与现有的数据从其他实验。系统地分析了π介子产生的各向异性。
英文摘要：
We present the results of a study of charged pion production in 12C + 12C collisions at incident beam energies of 1A GeV and 2A GeV using the HADES spectrometer at GSI. The main emphasis of the HADES program is on the dielectron signal from the early phase of the collision. Here, however, we discuss the data with respect to the emission of charged hadrons, specifically the production of pi+- mesons, which are related to neutral pions representing a dominant contribution to the dielectron yield. We have performed the first large-angular range measurement of the distribution of pi+- mesons for the 12C + 12C collision system covering a fairly large rapidity interval. The pion yields, transverse-mass and angular distributions are compared with calculations done within a transport model, as well as with existing data from other experiments. The anisotropy of pion production is systematically analyzed.
Study of exclusive one-pion and one-eta production using hadron and dielectron channels in pp reactions at kinetic beam energies of 1.25 GeV and 2.2 GeV with HADES
The double differential production cross sections, $d^2σ/dΩdE$, for hydrogen isotopes and charged pions in the reaction of p + Nb at 3.5 GeV proton beam energy have been measured by the High Acceptance DiElectron Spectrometer (HADES). Thanks to the high acceptance of HADES at forward emission angles and usage of its magnetic field, the measured energy range of hydrogen isotopes could be significantly extended in comparison to the relatively scarce experimental data available in the literature. The data provide information about the development of the intranuclear cascade in the proton-nucleus …
Helicity-Dependent Angular Distributions for Double-Charged-Pion Photoproduction
在Jefferson实验室Hall B使用能量范围在0.6 GeV和2.3 GeV之间的圆偏振标记光子束研究了γ p -> p pi+ pi-反应中的2 π介子光生。测量了末态粒子的角分布与束流螺旋度的关系。大横截面的不对称性，已被发现表现出强烈的敏感性的反应的运动学，并与初步模型计算Mokeev和罗伯茨。
At the leading twist, the transversity distribution function, $h^{q}_{1}(x)$, where $x$ is the longitudinal momentum fraction of the proton carried by quark $q$, encodes the transverse spin structure of the nucleon. Extraction of it is difficult because of its chiral-odd nature. In transversely polarized proton-proton collisions ($p^\uparrow p$), $h_{1}^{q}(x)$ can be coupled with another chiral-odd partner, a spin-dependent fragmentation function (FF). The resulting asymmetries in hadron(s) azimuthal correlations directly probe $h_{1}^{q}(x)$. We report the measurement of correlation asymmetr…
Helicity-Dependent Angular Distributions in Double-Charged-Pion Photoproduction
在杰斐逊实验室大厅B，使用能量范围在0.6 GeV和2.3 GeV之间的圆偏振标记光子束，研究了伽马+ p -> p + pi^+ + pi^-反应中的双π介子光生。由于CLAS探测器的大角度接受能力，测量了末态粒子的完全束螺旋度相关的角分布。大截面的不对称性表现出强烈的灵敏度的反应的运动学，并提供有价值的信息的反应动力学。初步结果。
We used an Isospin dependent Quantum Molecular Dynamics (IQMD) model to simulate Au + Au collisions at beam energy $E_{beam}$ = 1.23$A$ GeV, which corresponds to center of mass energy $\sqrt{s_{NN}} = 2.4$ GeV. Firstly, we obtained reasonable rapidity and transverse mass spectra of $π^-$ and $π^+$ as well as "apparent" temperature parameters in comparison with the HADES data. Then by calculating three-dimensional Hanbury Brown and Twiss (HBT) radius of same charged pion-pairs, we obtained the square difference of outward radius and sideward radius, i.e. $R_{out}^{2}-R_{side}^{2}$, as well as t…
Understanding the proton spin composition from the quarks and gluons spin polarization and their motion is important to test various kinds of sum rules and nonperturbative properties of hadrons. At the Relativistic Heavy Ion Collider (RHIC), we collide longitudinally polarized proton beams and measure the double helicity asymmetry $A_{LL}$, which is an important physical quantity for extracting the polarized parton distribution functions (PDFs) of the proton. Direct photon, jet and charged pion production are good channels to probe the gluon spin polarization inside the proton, with the abilit…
Comments concerning the paper "Measurement of negatively charged pion spectra in inelastic p+p interactions at 20, 31, 40, 80 and 158 GeV/c" by the NA61 collaboration
The near-threshold pion-induced $ϕ$ production off nuclei has been studied in the kinematical conditions of the HADES experiment using a collision model based on the nuclear spectral function. Starting from the elementary reaction ${π^-}p \to ϕn$, absolute differential and integral cross sections for the production of $ϕ$ mesons off a light carbon and a heavy tungsten target have been calculated and compared to the recently reported experimental cross sections. The absolute cross section values are shown to be sensitive to the effective nuclear scalar $ϕ$ and neutron potentials while the trans…
