Decays into {\pi}+{\pi}- of the f0(1370) scalar glueball candidate in pp central exclusive production experiments

The existence and properties of the f0(1370) scalar meson are rather well established from data of antiproton annihilations at rest. However conflicting results from Central Exclusive Production (CEP) experiments of the last millennium and ignorance of data from antiproton annihilations at rest in H2 and D2 bubble chambers have generated doubts on the very existence of the f0(1370). Properties of {\pi}+{\pi}- pairs produced in central exclusive production (CEP) reactions observed in old data together with data collected in the current decade at high energy colliders permit to show that {\pi}+{\pi}- decays of the f0(1370) meson are directly observable as an isolated peak between 1.1 and 1.6 GeV. Consequences of this observation and prospects for the identification of the scalar glueball ground-state are discussed.Comment: 20 pages, 11 figure

Last Upgrades of Roman Pot Electronics

This article presents the recent (2017-2018) electronics modifications for the upgrade of the TOTEM roman pot detectors at the CERN LHC. To improve the timing accuracy and reliability the new Roman Pot detector configuration utilizes both DSDD (Double Side Diamond Detector) and silicon (UFSD, Ultra Fast Silicon Detector) mounted on hybrid boards. The electronics described was designed, built and tested by the authors in Faculty of Electrical Engineering in Pilsen, Department of Applied Electronics and Telecommunications, University of West Bohemia and by the TOTEM experiment at CERN. With the new detector setup, timing measurements with resolution down to tens of picoseconds are possible.Peer reviewe

Irradiated Single Crystal Chemical Vapor Deposition Diamond Characterized with Various Ionizing Particles

The radiation hardness of diamond at the sensor level is studied by irradiating five sensors and studying them with various particle sources, without making any modifications to the sensors in between. The electronics used in the characterization is not irradiated to ensure that any observed effect is merely due to the sensor. Three sensors have received a fluence of 10 (14) protons cm(-2) and two 5 center dot 10 (15) protons cm(-2). At the lower fluence, the impact on the charge collection efficiency is very small, when the applied bias voltage is above 1 V mu m(-1). For the higher fluence, the charge collection efficiency is lower than expected based on earlier studies of diamond radiation hardness on the substrate level. Furthermore, it is noticed that the irradiation has a stronger impact on the signal amplitude recorded with a fast timing than with a charge sensitive amplifier.Peer reviewe

Characterisation of the dip-bump structure observed in proton-proton elastic scattering at root s=8 TeV

We describe an analysis comparing the p (p) over bar elastic cross section as measured by the D0 Collaboration at a center-of-mass energy of 1.96 TeV to that in pp collisions as measured by the TOTEM Collaboration at 2.76, 7, 8, and 13 TeVusing a model-independent approach. The TOTEM cross sections, extrapolated to a center-of-mass energy of root s = 1.96 TeV, are compared with the D0 measurement in the region of the diffractive minimum and the second maximum of the pp cross section. The two data sets disagree at the 3.4s level and thus provide evidence for the t-channel exchange of a colorless, C-odd gluonic compound, also known as the odderon. We combine these results with a TOTEM analysis of the same C-odd exchange based on the total cross section and the ratio of the real to imaginary parts of the forward elastic strong interaction scattering amplitude in pp scattering for which the significance is between 3.4s and 4.6s. The combined significance is larger than 5 sigma and is interpreted as the first observation of the exchange of a colorless, C-odd gluonic compound.Peer reviewe

Odderon Exchange from Elastic Scattering Differences between pp and p(p)over-bar Data at 1.96 TeV and from pp Forward Scattering Measurements

We describe an analysis comparing the p (p) over bar elastic cross section as measured by the D0 Collaboration at a center-of-mass energy of 1.96 TeV to that in pp collisions as measured by the TOTEM Collaboration at 2.76, 7, 8, and 13 TeVusing a model-independent approach. The TOTEM cross sections, extrapolated to a center-of-mass energy of root s = 1.96 TeV, are compared with the D0 measurement in the region of the diffractive minimum and the second maximum of the pp cross section. The two data sets disagree at the 3.4s level and thus provide evidence for the t-channel exchange of a colorless, C-odd gluonic compound, also known as the odderon. We combine these results with a TOTEM analysis of the same C-odd exchange based on the total cross section and the ratio of the real to imaginary parts of the forward elastic strong interaction scattering amplitude in pp scattering for which the significance is between 3.4s and 4.6s. The combined significance is larger than 5 sigma and is interpreted as the first observation of the exchange of a colorless, C-odd gluonic compound.Peer reviewe

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

First Search for Exclusive Diphoton Production at High Mass with Tagged Protons in Proton-Proton Collisions at root s=13 TeV

A search for exclusive two-photon production via photon exchange in proton-proton collisions, pp -> p gamma gamma p with intact protons, is presented. The data correspond to an integrated luminosity of 9.4 fb(-1) collected in 2016 using the CMS and TOTEM detectors at a center-of-mass energy of 13 TeVat the LHC. Events are selected with a diphoton invariant mass above 350 GeVand with both protons intact in the final state, to reduce backgrounds from strong interactions. The events of interest are those where the invariant mass and rapidity calculated from the momentum losses of the forward-moving protons match the mass and rapidity of the central, two-photon system. No events are found that satisfy this condition. Interpreting this result in an effective dimension-8 extension of the standard model, the first limits are set on the two anomalous four-photon coupling parameters. If the other parameter is constrained to its standard model value, the limits at 95% confidence level are vertical bar zeta(1)vertical bar < 2.9 x 10(-1)3 GeV-4 and vertical bar zeta(2)vertical bar < 6.0 x 10(-13) GeV-4.Peer reviewe

Measurement of the forward charged particle pseudorapidity density in pppp collisions at s=7\sqrt{s} = 7 TeV with the TOTEM experiment.

The TOTEM experiment at the LHC is dedicated to the precise measurement of the total $pp$ cross section, to the study of the elastic scattering and of the diffractive interactions. The TOTEM T2 telescope, composed of triple GEM chambers, provides the tracking of the charged particles produced by the inelastic $pp$ interactions in the pseudorapidity range 5.3$<$$|\eta|$$<$6.5. In this thesis the offline procedures developed for the event reconstruction in the T2 telescope are reported. They include the tuning of the detector simulation, the track reconstruction algorithm and their characterisation in terms of physics performance. The detector alignment algorithms are also described and the uncertainties on the misalignment parameters are quantified. The thesis is then focused on the measurement of the charged particle pseudorapidity density ($dN_{ch}/d\eta$) obtained in T2 for inelastic $pp$ collisions at $\sqrt{s}=$ 7 TeV. This extends the analogous measurement performed by the other LHC experiments to the previously unexplored forward $\eta$ region. The measurement refers to more than 99\% of non-diffractive processes and to single and double diffractive processes with diffractive masses above $\sim$3.4 GeV/c$^2$, corresponding to about 95\% of the total inelastic cross-section