Search for pseudoscalar bosons decaying into $e^+e^-$ pairs in the NA64 experiment at the CERN SPS
Yu. M. Andreev, D. Banerjee, J. Bernhard, V. E. Burtsev, N. Charitonidis, A. G. Chumakov, D. Cooke, P. Crivelli, E. Depero, A. V. Dermenev, S. V. Donskov, R. R.… 展开作者
Yu. M. Andreev, D. Banerjee, J. Bernhard, V. E. Burtsev, N. Charitonidis, A. G. Chumakov, D. Cooke, P. Crivelli, E. Depero, A. V. Dermenev, S. V. Donskov, R. R. Dusaev, T. Enik, A. Feshchenko, V. N. Frolov, A. Gardikiotis, S. G. Gerassimov, S. N. Gninenko, M. Hoesgen, M. Jeckel, V. A. Kachanov, A. E. Karneyeu, G. Kekelidze, B. Ketzer, D. V. Kirpichnikov, M. M. Kirsanov, V. N. Kolosov, I. V. Konorov, S. G. Kovalenko, V. A. Kramarenko, L. V. Kravchuk, N. V. Krasnikov, S. V. Kuleshov, V. E. Lyubovitskij, V. Lysan, V. A. Matveev, Yu. V. Mikhailov, L. Molina Bueno, D. V. Peshekhonov, V. A. Polyakov, B. Radics, R. Rojas, A. Rubbia, V. D. Samoylenko, H. Sieber, D. Shchukin, V. O. Tikhomirov, I. Tlisova, A. N. Toropin, A. Yu. Trifonov, B. I. Vasilishin, G. Vasquez Arenas, P. V. Volkov, V. Yu. Volkov, P. Ulloa
We report the results of a search for a light pseudoscalar particle $a$ that couples to electrons and decays to $e^+e^-$ performed using the high-energy CERN SPS H4 electron beam. If such pseudoscalar with a mass $\simeq 17$ MeV exists, it could explain the ATOMKI anomaly. We used the NA64 data samples collected in the "visible mode" configuration with total statistics corresponding to $8.4\times 10^{10}$ electrons on target (EOT) in 2017 and 2018. In order to increase sensitivity to small coupling parameter $ε$ we used also the data collected in 2016-2018 in the "invisible mode" configuration of NA64 with a total statistics corresponding to $2.84\times 10^{11}$ EOT. A thorough analysis of both these data samples in the sense of background and efficiency estimations was already performed and reported in our previous papers devoted to the search for light vector particles and axion-like particles (ALP). In this work we recalculate the signal yields, which are different due to different cross section and life time of a pseudoscalar particle $a$, and perform a new statistical analysis. As a result, the region of the two dimensional parameter space $m_a - ε$ in the mass range from 1 to 17.1 MeV is excluded. At the mass of the ATOMKI anomaly the values of $ε$ in the range $2.1 \times 10^{-4} < ε< 3.2 \times 10^{-4}$ are excluded.
$R_K$ and $K^+\rightarrowπ^+ν\barν with NA62 at CERN SPS
介绍了CERN SPS的NA 62实验的最新结果和展望。NA 62实验在两年的数据采集中对$K^+\rightarrow e^\pmν$和K^+ \rightarrow μ^ \pm ν $ decay rates using the full data set collected in 2007. The result is in agreement with the Standard Model expectation. The ultra-rare decay $ K^+ \rightarrow π^+ν \bar ν $ is an excellent processes to make tests of new physics at the highest scale complementary to the LHC thanks to their theoretically cleanness. The NA62 experiment at CERN SPS aims to collect of the order of 100 $ K^+ \rightarrow π^+ ν \bar ν$事件的比率$R_K$进行了最精确的测量，将本底保持在10%的水平。
NA 48/2收集了最大量的$K\to3 π$。对CP破坏效应敏感的电荷不对称性参数$A_g$，在三电荷π介子模（“带电”模）和两个中性π介子处于终态的模（“中性”模）中均得到了$10^{-4}$（初步）的测量精度.我们将讨论“中性”模式下的Dalitz图结构，以指出带电π介子再散射的影响。本文将介绍荷电模式下Dalitz图参数的新的初步测量结果
我们提出的最终结果实验NA 50的Charmonia生产在铅铅相互作用在158 A GeV。随着中心性的增加，观察到一个强大的增加抑制，对于JPSI和PSIPRIME共振。我们也提出了新的发展，关于jpsi和psiprime正常的核吸收测定推导出的质子核数据。它们与Pb-Pb结果的比较使我们能够得出结论，jpsi异常抑制集在中间中心，而S-U结果显示出与p-A行为的合理一致性。在S-U相互作用中，psiprime已经受到了明显更强的抑制，这在Pb-Pb系统中不断增加，并且与从p-A碰撞推导出的预期行为完全不相容。
The onset of the anomalous J/psi suppression in Pb-Pb collisions at the CERN SPS
NA 50实验观测到的J/psi抑制是158 AGeV的Pb-Pb碰撞中夸克-胶子等离子体形成的最显著特征之一。J/psi的生产已被研究作为一个函数的碰撞中心估计通过前向能量EZDC中释放的零度量热计（ZDC）。研究碰撞中参与核子的数量、Npart和EZDC之间的相关性，可以检查J/psi抑制模式与EZDC是否与表示为Npart函数的突然J/psi抑制机制兼容。
Can pion spectra in Pb+Pb collisions at CERN SPS energies be described by those in p+p reactions and energy-momentum conservation ? Rapidity distributions of pions in p+p and Pb+Pb collisions at CERN SPS energies
Experiments at the CERN SPS: first signals of deconfinement
INFN Padova（意大利国家核物理研究所帕多瓦分部）；CERN（欧洲核子研究组织）；Jan Kochanowski University（扬·科哈诺夫斯基大学）；Universidad Nacional Autonoma de Mexico（墨西哥国立自治大学）；Czech Technical University (ČVUT)（捷克理工大学）；INFN Torino（意大利国家核物理研究所都灵分部）；Weizmann Institute of Science（魏茨曼科学研究所）；University of Cagliari（卡利亚里大学）；INFN Cagliari（意大利国家核物理研究所卡利亚里分部）
Transverse momentum fluctuations and Δη-Δϕcorrelations in p+p interactions at the CERN SPS energies
NA 61/SHINE实验旨在发现强相互作用物质的临界点，并研究解除禁闭开始的性质。这些目标是通过测量质子-质子、质子-核和核-核相互作用中强子产生特性随碰撞能量和系统尺寸的变化来实现的。接近临界点的波动增加的预测。本文将介绍利用NA 61/SHINE能量扫描对p+p碰撞的横向动量涨落和两粒子赝快度/方位角关联的初步结果。这些新的结果将与NA 49中心Pb+Pb碰撞和模型预测的数据进行比较。
Measurements of Hadron Production in Pion-Carbon Interactions with NA61/SHINE at the CERN SPS
NA 61/SHINE是在CERN超级质子同步加速器上设计的一个固定靶实验，用于研究强子-质子、强子-核和核-核相互作用。在这一过程中，我们提出了在π介子-碳生产相互作用，这是根本的重要性，以改善广泛的空气簇射建模，从而解释超高能宇宙射线测量确定强子的光谱结果。特别是，我们的测量（反）重子和$ρ^0$生产的π-碳相互作用可以有助于改善预测的μ子生产的空气簇射模拟使用强子相互作用模型。在这篇文章中，我们讨论了数据分析和结果从介子-碳碰撞记录在束流动量为158和350 GeV/c。初步频谱的$K^{\pm}$和$p$（$\bar{p}$），以及比较预测的强子相互作用模型中使用的空气簇射模拟。此外，我们目前的最终结果的生产$ρ^0$，$ω$和$K^{0*}$共振。
