Measurement of the analysing power in proton-proton elastic scattering at small angles
Z. Bagdasarian, D. Chiladze, S. Dymov, A. Kacharava, G. Macharashvili, S. Barsov, R. Gebel, B. Gou, M. Hartmann, I. Keshelashvili, A. Khoukaz, P. Kulessa, A. Ku… 展开作者
Z. Bagdasarian, D. Chiladze, S. Dymov, A. Kacharava, G. Macharashvili, S. Barsov, R. Gebel, B. Gou, M. Hartmann, I. Keshelashvili, A. Khoukaz, P. Kulessa, A. Kulikov, A. Lehrach, N. Lomidze, B. Lorentz, R. Maier, D. Mchedlishvili, S. Merzliakov, S. Mikirtychyants, M. Nioradze, H. Ohm, M. Papenbrock, D. Prasuhn, F. Rathmann, V. Serdyuk, V. Shmakova, R. Stassen, H. Stockhorst, I. I. Strakovsky, H. Ströher, M. Tabidze, A. Täschner, S. Trusov, D. Tsirkov, Yu. Uzikov, Yu. Valdau, C. Wilkin, R. L. Workman
The proton analysing power in $\vec{p}p$ elastic scattering has been measured at small angles at COSY-ANKE at 796 MeV and five other beam energies between 1.6 and 2.4 GeV using a polarised proton beam. The asymmetries obtained by detecting the fast proton in the ANKE forward detector or the slow recoil proton in a silicon tracking telescope are completely consistent. Although the analysing power results agree well with the many published data at 796 MeV, and also with the most recent partial wave solution at this energy, the ANKE data at the higher energies lie well above the predictions of this solution at small angles. An updated phase shift analysis that uses the ANKE results together with the World data leads to a much better description of these new measurements.
It is shown that the ratio of the deuteron and proton analysing powers in proton-deuteron elastic scattering at small angles is sensitive to subtle effects in a theoretical description. These include the transverse spin-spin term in the elementary nucleon-nucleon amplitudes and double-scattering corrections. On the other hand there is far less sensitivity to the spin-orbit amplitude and to binding or other kinematic effects associated with the use of the deuteron, as either target or projectile. The available data are in agreement with the results of a refined Glauber theory model.
Unpolarized electron-proton elastic scattering cross-section measurements at high $Q^2$ allow for improved extractions of the proton electromagnetic form factors as well as provide constraints on possible hard two-photon exchange effects. We present a detailed study of the feasibility of making these high $Q^2$ e-p elastic measurements at the future Electron-Ion Collider (EIC). The results show that e-p elastic cross sections can be obtained in the momentum transfer range of $6~(GeV/c)^2 < Q^2 < 40~(GeV/c)^2$, which would be the highest-ever $Q^2$ values measured. These data will all be at vir…
A comparison between polarization-transfer to a bound proton in quasi-free kinematics by the A$(\vec{e},e'\vec p)$ knockout reaction and that in elastic scattering off a free proton can provide information on the characteristics of the bound proton. In the past the reported measurements have been compared to those of a free proton with zero initial momentum. We introduce, for the first time, expressions for the polarization-transfer components when the proton is initially in motion and compare them to the $^2$H data measured at the Mainz Microtron (MAMI). We show the ratios of the transverse (…
The proton--proton elastic differential cross section at very small four momentum transfer squared has been measured at three different incident proton momenta in the range of 2.5 to 3.2 GeV/c by detecting the recoil proton at polar angles close to $90^\circ$. The measurement was performed at COSY with the KOALA detector covering the Coulomb-nuclear interference region. The total cross section $σ_\text{tot}$, which has been determined precisely, is consistent with previous measurements. The values of the slope parameter $B$ and the relative real amplitude ratio $ρ$ determined in this experimen…
Measurements of the proton's form factor ratio made with polarization transfer show a striking discrepancy relative to the ratio extracted from unpolarized elastic electron-proton scattering cross sections. One hypothesis is that the discrepancy is caused by hard two-photon exchange (TPE), a typically neglected radiative correction that may bias the two approaches differently. This hypothesis has been challenging to confirm. Theoretical estimates of TPE are model-dependent, and recent experimental determinations of TPE lacked the kinematic reach to be conclusive. The possible impact of TPE rem…
Available data on the polarization of the secondary proton (as a function of its momentum $K$) in the inelastic ({\it p, p$'$}) reactions with the $^{9}$Be, $^{12}$C, and $^{40}$Ca nuclei and differential cross section data (the momentum distributions) for the reactions at the initial proton energy 1 GeV and scattering angles $Θ$=21$^\circ$ and $Θ$=24.5$^\circ$ were analysed in a range of the high momenta $K$ close to the momentum corresponding to the proton elastic scattering off the investigated nucleus. A structure in the polarization and momentum distribution data at the high momenum $K$, …
Proton elastic form factor ratios to $Q^2$ = 3.5 GeV$^2$ by polarization transfer
质子弹性电磁形状因子的比率，$G_{Ep}/G_{Mp}$，通过测量$P_{t}$和$P_{\ell}$，横向和纵向反冲质子极化分量，分别为弹性$\vec e p \to e\vec p$ ~反应在四动量转移平方范围为0.5至3.5 GeV的$^2$。在单光子交换近似中，比率$G_{Ep}/G_{Mp}$与比率$P_t/P_{\ell}$成正比。在旋光仪中同时测量$P_{t}$和$P_{\ell}$可减少系统的不确定性。比率$G_{Ep}/G_{Mp}$的结果显示随着$Q^2$的增加而系统性地降低，这首次表明质子中电荷和磁化强度的分布存在明确的差异。这些数据已经过重新分析，系统不确定性比以前公布的结果明显小。
Proton elastic scattering from tin isotopes at 295 MeV and systematic change of neutron density distributions
在295 MeV的质子弹性散射截面和分析能力从$^{116,118,120,122,124}$锡已被测量的动量转移高达约3.5 fm $^{-1}$推断系统的中子密度分布的变化。我们调整的相对论洛夫-弗兰尼相互作用，以解释质子的弹性散射的核的密度分布是众所周知的。然后，我们应用这种相互作用推导了锡同位素的中子密度分布。我们的分析结果表明，随着质量数的增加，锡同位素的中子皮厚度逐渐增加的明显的系统行为。
The first result of the pp2pp experiment at RHIC on elastic scattering of polarized protons at sqrt{s} = 200 GeV is reported here. The exponential slope parameter b of the diffractive peak of the elastic cross section in the t range 0.010 <= |t| <= 0.019 (GeV/c)^2 was measured to be b = 16.3 +- 1.6 (stat.) +- 0.9 (syst.) (GeV/c)^{-2} .
The KOALA experiment measures the differential cross section of (anti)proton-proton elastic scattering over a wide range of four-momentum transfer squared 0.0008 < |t| < 0.1 (GeV/c)$^2$ . The forward scattering parameters and the absolute luminosity can be deduced by analyzing the characteristic shape of the differential cross-section spectrum. The experiment is based on fixed target kinematics and uses an internal hydrogen cluster jet target. The wide range of |t| is achieved by measuring the total kinetic energy of the recoil protons near 90° with a recoil detector, which consists of silicon…
We describe a physics program at the Relativistic Heavy Ion Collider (RHIC) with tagged forward protons. The program started with the proton-proton elastic scattering experiment (PP2PP), for which a set of Roman Pot stations was build. The PP2PP experiment took data at RHIC as a dedicated experiment at the beginning of RHIC operations. To expand the physics program to include non-elastic channels with forward protons, like Central Exclusive Production (CEP), Central Production (CP) and Single Diffraction Dissociation (SD), the experiment with its equipment was merged with the STAR experiment a…
We report the first results on differential, total and elastic cross sections in proton-proton collisions at the Relativistic Heavy Ion Collider (RHIC) at $\sqrt{s}=200$ GeV. The data lwere obtained with the Roman Pot Detector subsystem of the STAR experiment. The data used for this analysis cover the four-momentum transfer squared ~($t$) range $ 0.045 \le |t| \le 0.135$ (GeV/c)$^2$. The Roman Pot system was placed downstream of the STAR detector. During the data taking the Roman Pots were moved to ~8$σ_{y}$, the vertical distance of from the beam center. They were operated during standard dat…
A model independent Levy expansion method is introduced to describe nearly Levy shaped squared moduli of Fourier transforms. We apply this method to precisely characterize the most recent elastic scattering data of proton-proton collisions at $\sqrt{s} = 13$ TeV. The results reveal a substructure of protons, which is found to be significantly larger and darker in high energy proton-proton collisions at the TeV scale, as compared to a rather faint and apparently overlooked sub-structure, that we also identify in elastic proton-proton scattering at the ISR energy range of $\sqrt{s} = 23 - 62$ Ge…
We complete the model-independent analysis of the scaling properties of the differential cross section of elastic proton-proton cross sections, including new TOTEM data published in 2022 at $\sqrt{s} = 8$ TeV. We separate the signal and the background region with a new gating method. In the signal region, we find that the statistical significance of Odderon exchange from the combined 7.0 and 8.0 TeV $pp$ data of TOTEM and the 1.96 TeV $p\bar{p}$ data of D0 is at least 7.32$σ$. In the background region, the scaling functions of elastic proton-proton data at 7 and 8 TeV and that of elastic proto…
We investigate the scaling properties of elastic scattering data at ISR and LHC energies and find that the significance of an Odderon observation is larger than the discovery threshold of 5$σ$. As an unexpected by-product of these investigations, for certain experimentally relevant cases, we also conjecture the possibility of proton holography with the help of elastic proton-proton scattering.
