Quantitative global-local mixing for accessible skew products

We study global-local mixing for accessible skew products with a mixing base. For a dense set of almost periodic global observables, we prove rapid mixing; and for a dense set of global observables vanishing at infinity, we prove polynomial mixing. More generally, we relate the speed of mixing to the "low frequency behaviour" of the spectral measure associated to our global observables. Our strategy relies on a careful choice of the spaces of observables and on the study of a family of twisted transfer operators

The First 1 1/2 Years of TOTEM Roman Pot Operation at LHC

Since the LHC running season 2010, the TOTEM Roman Pots (RPs) are fully operational and serve for collecting elastic and diffractive proton-proton scattering data. Like for other moveable devices approaching the high intensity LHC beams, a reliable and precise control of the RP position is critical to machine protection. After a review of the RP movement control and position interlock system, the crucial task of alignment will be discussed.Comment: 3 pages, 6 figures; 2nd International Particle Accelerator Conference (IPAC 2011), San Sebastian, Spain; contribution MOPO01

Proton-proton elastic scattering at the LHC energy of {\surd} = 7 TeV

Proton-proton elastic scattering has been measured by the TOTEM experiment at the CERN Large Hadron Collider at {\surd}s = 7 TeV in dedicated runs with the Roman Pot detectors placed as close as seven times the transverse beam size (sbeam) from the outgoing beams. After careful study of the accelerator optics and the detector alignment, |t|, the square of four-momentum transferred in the elastic scattering process, has been determined with an uncertainty of d t = 0.1GeV p|t|. In this letter, first results of the differential cross section are presented covering a |t|-range from 0.36 to 2.5GeV2. The differential cross-section in the range 0.36 < |t| < 0.47 GeV2 is described by an exponential with a slope parameter B = (23.6{\pm}0.5stat {\pm}0.4syst)GeV-2, followed by a significant diffractive minimum at |t| = (0.53{\pm}0.01stat{\pm}0.01syst)GeV2. For |t|-values larger than ~ 1.5GeV2, the cross-section exhibits a power law behaviour with an exponent of -7.8_\pm} 0.3stat{\pm}0.1syst. When compared to predictions based on the different available models, the data show a strong discriminative power despite the small t-range covered.Comment: 12pages, 5 figures, CERN preprin

Diamond Detectors for the TOTEM Timing Upgrade

This paper describes the design and the performance of the timing detector developed by the TOTEM Collaboration for the Roman Pots (RPs) to measure the Time-Of-Flight (TOF) of the protons produced in central diffractive interactions at the LHC. The measurement of the TOF of the protons allows the determination of the longitudinal position of the proton interaction vertex and its association with one of the vertices reconstructed by the CMS detectors. The TOF detector is based on single crystal Chemical Vapor Deposition (scCVD) diamond plates and is designed to measure the protons TOF with about 50 ps time precision. This upgrade to the TOTEM apparatus will be used in the LHC run 2 and will tag the central diffractive events up to an interaction pileup of about 1. A dedicated fast and low noise electronics for the signal amplification has been developed. The digitization of the diamond signal is performed by sampling the waveform. After introducing the physics studies that will most profit from the addition of these new detectors, we discuss in detail the optimization and the performance of the first TOF detector installed in the LHC in November 2015.Comment: 26 pages, 18 figures, 2 tables, submitted for publication to JINS

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

The TOTEM collaboration at the CERN LHC has measured the differential cross-section of elastic proton-proton scattering at root s = 8 TeV in the squared four-momentum transfer range 0.2 GeV2 &lt; vertical bar t vertical bar &lt; 1.9 GeV2. This interval includes the structure with a diffractive minimum ("dip") and a secondary maximum ("bump") that has also been observed at all other LHC energies, where measurements were made. A detailed characterisation of this structure for root s = 8 TeV yields the positions, vertical bar t vertical bar(dip) = (0.521 +/- 0.007) GeV2 and vertical bar t vertical bar(bump) = (0.695 +/- 0.026) GeV2, as well as the cross-section values, d sigma/dt vertical bar(dip) = (15.1 +/- 2.5) mu b/GeV2 and d sigma/dt vertical bar(bump) = (29.7 +/- 1.8) mu b/Ge-2, for the dip and the bump, respectively

Elastic differential cross-section dσ/dt{\rm d}\sigma/{\rm d}t at s=\sqrt{s}=2.76 TeV and implications on the existence of a colourless 3-gluon bound state

The proton-proton elastic differential cross section ${\rm d}\sigma/{\rm d}t$ has been measured by the TOTEM experiment at $\sqrt{s}=2.76$ TeV energy with $\beta^{*}=11$ m beam optics. The Roman Pots were inserted to 13 times the transverse beam size from the beam, which allowed to measure the differential cross-section of elastic scattering in a range of the squared four-momentum transfer ($|t|$) from $0.36$ GeV$^{2}$ to $0.74$ GeV$^{2}$. The differential cross-section can be described with an exponential in the $|t|$-range between $0.36$ GeV$^{2}$ and $0.54$ GeV$^{2}$, followed by a diffractive minimum (dip) at $|t_{\rm dip}| = 0.61 \pm 0.03$ GeV$^{2}$ and a subsequent maximum (bump). The ratio of the ${\rm d}\sigma/{\rm d}t$ at the bump and at the dip is $1.7\pm 0.2$. When compared to the $\rm p\bar{p}$ measurement of the D0 experiment at $\sqrt s = 1.96$ TeV, a significant difference can be observed. Under the condition that the effects due to the energy difference between TOTEM and D0 can be neglected, the result provides evidence for a colourless 3-gluon bound state exchange in the $t$-channel of the proton-proton elastic scattering.Comment: 75 authors, 17 pages, 10 figures, 3 table

Elastic differential cross-section dσ/dt at s√=2.76 TeV and implications on the existence of a colourless C-odd three-gluon compound state

The proton–proton elastic differential cross section dσ/dt has been measured by the TOTEM experiment at s√=2.76 TeV energy with β∗=11 m beam optics. The Roman Pots were inserted to 13 times the transverse beam size from the beam, which allowed to measure the differential cross-section of elastic scattering in a range of the squared four-momentum transfer (|t|) from 0.36 to 0.74 GeV2. The differential cross-section can be described with an exponential in the |t|-range between 0.36 and 0.54 GeV2, followed by a diffractive minimum (dip) at |tdip|=(0.61±0.03) GeV2 and a subsequent maximum (bump). The ratio of the dσ/dt at the bump and at the dip is 1.7±0.2. When compared to the proton–antiproton measurement of the D0 experiment at s√=1.96 TeV, a significant difference can be observed. Under the condition that the effects due to the energy difference between TOTEM and D0 can be neglected, the result provides evidence for the exchange of a colourless C-odd three-gluon compound state in the t-channel of the proton–proton and proton–antiproton elastic scattering

Elastic differential cross-section d sigma/dt at root s=2.76 TeV and implications on the existence of a colourless C-odd three-gluon compound state

The proton-proton elastic differential cross sectvion d sigma/dt has been measured by the TOTEM experiment at root s = 2.76 TeV energy with beta* = 11 m beam optics. The Roman Pots were inserted to 13 times the transverse beam size from the beam, which allowed tomeasure the differential cross-section of elastic scattering in a range of the squared four-momentum transfer (vertical bar t vertical bar) from 0.36 to 0.74 GeV2. The differential cross-section can be described with an exponential in the vertical bar t vertical bar-range between 0.36 and 0.54 GeV2, followed by a diffractive minimum (dip) at vertical bar t(dip)vertical bar = (0.61 +/- 0.03) GeV2 and a subsequent maximum (bump). The ratio of the ds/dt at the bump and at the dip is 1.7 +/- 0.2. When compared to proton-antiproton measurement of the D0 experiment at root s = 1.96 TeV, a significant difference can be observed. Under the condition that the effects due to the energy difference between TOTEM and D0 can be neglected, the result provides evidence for the exchange of a colourless C-odd three-gluon compound state in the t-channel of the proton-proton and proton-antiproton elastic scattering.Peer reviewe

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

The TOTEM collaboration at the CERN LHC has measured the differential cross-section of elastic proton-proton scattering at root s = 8 TeV in the squared four-momentum transfer range 0.2 GeV2 &lt; vertical bar t vertical bar &lt; 1.9 GeV2. This interval includes the structure with a diffractive minimum ("dip") and a secondary maximum ("bump") that has also been observed at all other LHC energies, where measurements were made. A detailed characterisation of this structure for root s = 8 TeV yields the positions, vertical bar t vertical bar(dip) = (0.521 +/- 0.007) GeV2 and vertical bar t vertical bar(bump) = (0.695 +/- 0.026) GeV2, as well as the cross-section values, d sigma/dt vertical bar(dip) = (15.1 +/- 2.5) mu b/GeV2 and d sigma/dt vertical bar(bump) = (29.7 +/- 1.8) mu b/Ge-2, for the dip and the bump, respectively