Evidence for non-exponential elastic proton-proton differential cross-section at low |t| and sqrt(s) = 8 TeV by TOTEM

The TOTEM experiment has made a precise measurement of the elastic proton-proton differential cross-section at the centre-of-mass energy sqrt(s) = 8 TeV based on a high-statistics data sample obtained with the beta* = 90 optics. Both the statistical and systematic uncertainties remain below 1%, except for the t-independent contribution from the overall normalisation. This unprecedented precision allows to exclude a purely exponential differential cross-section in the range of four-momentum transfer squared 0.027 < |t| < 0.2 GeV^2 with a significance greater than 7 sigma. Two extended parametrisations, with quadratic and cubic polynomials in the exponent, are shown to be well compatible with the data. Using them for the differential cross-section extrapolation to t = 0, and further applying the optical theorem, yields total cross-section estimates of (101.5 +- 2.1) mb and (101.9 +- 2.1) mb, respectively, in agreement with previous TOTEM measurements.Comment: Final version published in Nuclear Physics

Measurement of the forward charged particle pseudorapidity density in pp collisions at root s=8 TeV using a displaced interaction point

The pseudorapidity density of charged particles dN(ch)/d(eta) is measured by the TOTEM experiment in proton-proton collisions at root s = 8 TeV within the range 3.9 &lt; eta &lt; 4.7 and -6.95 &lt; eta &lt; -6.9. Data were collected in a low intensity LHC run with collisions occurring at a distance of 11.25 m from the nominal interaction point. The data sample is expected to include 96-97 % of the inelastic proton-proton interactions. The measurement reported here considers charged particles with p(T) &gt; 0 MeV/c, produced in inelastic interactions with at least one charged particle in -7 &lt; eta &lt; -6 or 3.7 &lt; eta &lt; 4.8. The dN(ch)/d eta has been found to decrease with vertical bar eta vertical bar, from 5.11 +/- 0.73 at eta = 3.95 to 1.81 +/- 0.56 at eta = -6.925. Several Monte Carlo generators are compared to the data and are found to be within the systematic uncertainty of the measurement

Flaveria anomala B.L. Rob.

The TOTEM collaboration has measured the proton–proton total cross section at $$\sqrt{s}=13~\hbox {TeV}$$ with a luminosity-independent method. Using dedicated $$\beta ^{*}=90~\hbox {m}$$ beam optics, the Roman Pots were inserted very close to the beam. The inelastic scattering rate has been measured by the T1 and T2 telescopes during the same LHC fill. After applying the optical theorem the total proton–proton cross section is $$\sigma _\mathrm{tot}=(110.6~\pm ~3.4$$) mb, well in agreement with the extrapolation from lower energies. This method also allows one to derive the luminosity-independent elastic and inelastic cross sections: $$\sigma _\mathrm{el}=(31.0~\pm ~1.7)~\hbox {mb}$$ and $$\sigma _\mathrm{inel}=(79.5~\pm ~1.8)~\hbox {mb}$$