A measurement of the total $pp$ cross section at the LHC at $\sqrt{s}=7$ TeV is presented. In a special run with high-$\beta^{\star}$ beam optics, an integrated luminosity of 80 $\mu$b$^{-1}$ was accumulated in order to measure the differential elastic cross section as a function of the Mandelstam momentum transfer variable $t$. The measurement is performed with the ALFA sub-detector of ATLAS. Using a fit to the differential elastic cross section in the $|t|$ range from 0.01 GeV$^2$ to 0.1 GeV$^2$ to extrapolate to $|t|\rightarrow 0$, the total cross section, $\sigma_{\mathrm{tot}}(pp\rightarrow X)$, is measured via the optical theorem to be: $$\sigma_{\mathrm{tot}}(pp\rightarrow X) = 95.35 \; \pm 0.38 \; ({\mbox{stat.}}) \pm 1.25 \; ({\mbox{exp.}}) \pm 0.37 \; (\mbox{extr.}) \; \mbox{mb},$$ where the first error is statistical, the second accounts for all experimental systematic uncertainties and the last is related to uncertainties in the extrapolation to $|t|\rightarrow 0$. In addition, the slope of the elastic cross section at small $|t|$ is determined to be $B = 19.73 \pm 0.14 \; ({\mbox{stat.}}) \pm 0.26 \; ({\mbox{syst.}}) \; \mbox{GeV}^{-2}$.
The measured total cross section, the first systematic error accounts for all experimental uncertainties and the second error for the extrapolation t-->0.
The nuclear slope of the differential eslastic cross section at small |t|, the first systematic error accounts for all experimental uncertainties and the second error for the extrapolation t-->0.
The Optical Point dsigma/(elastic)/dt(t-->0), the total elastic cross section and the observed elastic cross section within the fiducial volume. The first systematic error accounts for all experimental uncertainties and the second error for the extrapolation t-->0.
A measurement of the total $pp$ cross section at the LHC at $\sqrt{s}=8$ TeV is presented. An integrated luminosity of $500$ $\mu$b$^{-1}$ was accumulated in a special run with high-$\beta^{\star}$ beam optics to measure the differential elastic cross section as a function of the Mandelstam momentum transfer variable $t$. The measurement is performed with the ALFA sub-detector of ATLAS. Using a fit to the differential elastic cross section in the $-t$ range from $0.014$ GeV$^2$ to $0.1$ GeV$^2$ to extrapolate $t\rightarrow 0$, the total cross section, $\sigma_{\mathrm{tot}}(pp\rightarrow X)$, is measured via the optical theorem to be: $\sigma_{\mathrm{tot}}(pp\rightarrow X) = {96.07} \; \pm 0.18 \; ({{stat.}}) \pm 0.85 \; ({{exp.}}) \pm 0.31 \; ({extr.}) \; {mb} \;,$ where the first error is statistical, the second accounts for all experimental systematic uncertainties and the last is related to uncertainties in the extrapolation $t\rightarrow 0$. In addition, the slope of the exponential function describing the elastic cross section at small $t$ is determined to be $B = 19.74 \pm 0.05 \; ({{stat.}}) \pm 0.23 \; ({{syst.}}) \; {GeV}^{-2}$.
The measured total cross section, the first systematic error accounts for all experimental uncertainties and the second error for the extrapolation t-->0.
The nuclear slope of the differential eslastic cross section at small |t|, the first systematic error accounts for all experimental uncertainties and the second error for the extrapolation t-->0.
The total elastic cross section and the observed elastic cross section within the fiducial volume.
We have measured the difference between the pp total cross-sections for parallel and anti-parallel longitudinal spin states at beam momenta of 3 and 6 GeV/ c . These results, combined with our previous measurements, at lower momenta, are useful in clarifying a striking structure appearing at around 1.5 GeV/ c . We have also measured for the first time, the spin-spin correlation parameter C LL ( t ) in pp elastic scattering at 6 GeV/ c . We observe evidence for an exchange with A 1 -like quantum-numbers.
NOTE: HIGHER -T DATA ARE BEING ANALYSED. PUBLISHED GRAPH HAS LARGER ERRORS.
THESE NUMBERS APPEAR TO UPDATE THOSE REPORTED IN I. P. AUER ET AL., PRL 37, 1727 (76). NOTE: DATA MAY HAVE SMALLER ERROR BARS IN THE FINAL ANALYSIS.
NOTE: MORE DATA ARE BEING ANALYSED. SINCE THE POLARIZED TARGET MAGNETIC FIELD WAS TILTED AT 18 DEG AWAY FROM THE BEAM DIRECTION, THE MEASURED CSL CONTAINS AN ADMIXTURE OF CSS. THE CSL VALUES QUOTED HERE HAVE BEEN CORRECTED FOR THIS EFFECT USING THE EXPERIMENTAL VALUES OF CSS.
Measurements are reported of the difference ΔσL between proton-proton total cross sections for parallel and antiparallel spin states and of the parameter CLL for proton-proton elastic scattering near 90°, for thirteen energies between 300 and 800 MeV. The ΔσL results agree well with previous ANL ZGS and SIN data, but disagree with recent results from TRIUMF. Attempts to understand the cause of the discrepancy have been unsuccessful, but possible sources are discussed. The ΔσL and CLL results have been used with other experimental data to extract quantities which depend only on spin-singlet, coupled spin-triplet, and spin-triplet partial waves. Structure is found in these quantities, which appears to be associated with the resonantlike D21 and F33 partial waves. Additional similar structure is also found, which may be due either to the P03 partial wave or the (P23,F23) partial-wave pair.
ERRORS ARE STATISTICAL ONLY. THERE IS ADDITION OF 2.0 AND 2.1 PCT SYSTEMATICS.
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The differential cross sections for the elastic scattering of π+, π−, K+, K−, p, and p¯ on protons have been measured in the t interval -0.04 to -0.75 GeV2 at five momenta: 50, 70, 100, 140, and 175 GeV/c. The t distributions have been parametrized by the quadratic exponential form dσdt=Aexp(B|t|+C|t|2) and the energy dependence has been described in terms of a single-pole Regge model. The pp and K+p diffraction peaks are found to shrink with α′∼0.20 and ∼0.15 GeV−2, respectively. The p¯p diffraction peak is antishrinking while π±p and K−p are relatively energy-independent. Total elastic cross sections are calculated by integrating the differential cross sections. The rapid decline in σel observed at low energies has stopped and all six reactions approach relatively constant values of σel. The ratio of σelσtot approaches a constant value for all six reactions by 100 GeV, consistent with the predictions of the geometric-scaling hypothesis. This ratio is ∼0.18 for pp and p¯p, and ∼0.12-0.14 for π±p and K±p. A crossover is observed between K+p and K−p scattering at |t|∼0.19 GeV2, and between pp and p¯p at |t|∼0.11 GeV2. Inversion of the cross sections into impact-parameter space shows that protons are quite transparent to mesons even in head-on collisions. The probability for a meson to pass through a proton head-on without interaction inelastically is ∼20% while it is only ∼6% for an incident proton or antiproton. Finally, the results are compared with various quark-model predictions.
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Measurements of the polarization parameter and angular distributions in pp elastic scattering at incident energies of 100 and 300 GeV are reported. The data cover the kinematic range 0.18<−t<2.0 GeV2. They are found to be consistent with absorption-model predictions.
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THE ANGULAR DISTRIBUTION IN THE PUBLISHED FIGURE IS NORMALIZED TO D(SIG)/DT AT -T = 0.55 GEV**2 FROM AKERLOF ET AL., PR D14, 2864 (1976).
Measurements of C LL of pp elastic scattering near θ c.m. = 90° at thirteen energies between 300 and 800 MeV are reported. These, together with previous values of C NN , are used to extract values of two quantities, ƒ s and ƒ t , which contain only spin-singlet and only coupled spin-triplet partial waves, respectively. The ƒ s curve, which is not dependent on C LL , exhibits the behavior expected for the previously conjectured 1 D 2 resonance. The ƒ t curve also exhibits a resonance-like behavior, which could be due either to the 3 P 0 or the 3 P 2 partial wave.
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We have made the first measurement of the spin-spin correlation parameter CSS in pp elastic scattering at 6 GeV/c over the |t| range from 0.05 to 1.5 (GeV/c)2. The measured CSS data points are all negative, and their absolute values increase with |t|. The results are compared with some existing attempts to describe the pp scattering process.
NUMERICAL VALUES OBTAINED FROM AUTHORS. MAGNETIC FIELD ALIGNMENT AND APERTURE EFFECTS MEAN THAT QUANTITY ACTUALLY MEASURED IS 0.98 CSS + 0.02 CNN - 0.12 CSL. SEE LATER NUMBERS IN THE RECORD OF I. P. AUER ET AL., PL 70B, 475 (1977).
We have measured the spin-spin correlation parameter CNN at 2, 3, 4, and 6 GeV/c over the |t| range of 0.1 to 2.0 (GeV/c)2 and have observed a striking energy and |t| dependence in CNN. Polarization data were simultaneously collected and are compared to previous results.
CNN PARAMETER MEASURED.
Toward the goal of experimentally determining pp elastic scattering amplitudes at 6 GeV/c, we have measured a linear combination of triple-spin correlation parameters and also a linear combination of spintransfer parameters over the |t| range between 0.2 and 1.0 (GeV/c)2. A horizontally polarized beam (S direction) was obtained by precessing the spin of the polarized beam from the Argonne Zero Gradient Synchrotron using a superconducting solenoid. The target protons were polarized vertically (N direction) and the polarization of the recoil protons was measured with a carbon polarimeter. The results are consistent with the amplitude corresponding to π exchange being almost real and positive.
KSS = (S00S) AND HSNS = (SN0S) MEASURED HERE CONTAIN SMALL ADMIXTURES OF THE OTHER SPIN-TRANSFER AND TRIPLE-SPIN CORRELATION PARAMETERS RESPECTIVELY DUE TO THE POLARIZED TARGET MAGNETIC FIELD - SEE TEXT. MEAN VALUE OF HSNS OVER THIS T-RANGE IS 0.098 +- 0.085. PARITY CONSERVATION REQUIRES THE VANISHING OF THE PARAMETERS KSN, HSNN, (000S) AND DNS, WHILE (000N) MUST AGREE WITH THE SINGLE SCATTERING POLARIZATION PARAMETER (0N00).
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