117455561
New physics limits from kaon decays
Searches for lepton flavour violation and lepton number violation in kaon decays by the NA62 and NA48/2 experiments at CERN are presented. A new measurement of the ratio of charged kaon leptonic decay rates $R_K=\Gamma(K_{e2})/\Gamma(K_{\mu2})$ to sub-percent relative precision is discussed. An improved upper limit on the lepton number violating $K^\pm\rightarrow\pi^\mp\mu^\pm\mu^\pm$ decay rate is also reported. The future 10% precision measurement of the branching ratio of the ultra-rare kaon decay $K^+\rightarrow\pi^+\nu\bar{\nu}$ with the NA62 experiment is finally reviewed.
120424159
The NA62 Experiment at CERN
The NA62 experiment, which aims to measure the branching ratio of the very rare kaon decay K + → π + ν ν ¯ at the CERN SPS, is described. The proposed experiment aims to collect some 100 K + → π + ν ν ¯ events with a 10% of background. The status and the future perspectives for the experiment are discussed.
103455858
The NA62 Experiment: Prospects for the $K^+ \to \pi^+ \nu \bar\nu$ Measurement
122483903
Pion-Muon separation with a RICH prototype for the NA62 experiment
Abstract The NA62 experiment at CERN, aimed to measure K + → π + ν ν ¯ branching fraction (O(10 −10 )), relies on a Neon based RICH detector for π / μ separation, time measurement and level 0 trigger. The experimental requirements for this detector are: a muon contamination in pion samples lower than 5×10 −3 in the momentum range 15–35 GeV/ c and a time resolution on the charged track better than 100 ps. A prototype of such a detector was built and tested in 2009; it consists of a full length ( ≈ 18 m ) Ne filled vessel equipped with a spherical mirror and 414 PMs on its focal plane, located about 17 m upstream of the mirror. This prototype was tested at CERN SPS on a positive hadron beam, in the required momentum range, to measure the π / μ separation and to confirm the time resolution obtained with a previous prototype; the μ misidentification probability is about 0.7% and the time resolution is better than 100 ps in the whole momentum range.
117703483
$R_K$ and $K^+\rightarrow\pi^+\nu\bar{\nu} with NA62 at CERN SPS
Recent results a future prospects of the NA62 experiment at CERN SPS are presented. The NA62 experiment performed the most precise measurement of the ratio $R_K$ of the $K^+\rightarrow e^\pm\nu$ and K^+\rightarrow \mu^\pm\nu$ decay rates using the full data set collected in 2007. The result is in agreement with the Standard Model expectation. The ultra-rare decay $K^+\rightarrow\pi^+\nu\bar{\nu}$ is an excellent processes to make tests of new physics at the highest scale complementary to the LHC thanks to their theoretically cleanness. The NA62 experiment at CERN SPS aims to collect of the order of 100 $K^+\rightarrow\pi^+\nu\bar{\nu}$ events in two years of data taking, keeping the background at the level of 10%.
22796813
Double diffractive cross-section measurement in the forward region at the LHC.
The first double diffractive cross-section measurement in the very forward region has been carried out by the TOTEM experiment at the LHC with a center-of-mass energy of sqrt[s]=7  TeV. By utilizing the very forward TOTEM tracking detectors T1 and T2, which extend up to |η|=6.5, a clean sample of double diffractive pp events was extracted. From these events, we determined the cross section σDD=(116±25)  μb for events where both diffractive systems have 4.7<|η|min<6.5.
67834315
Luminosity-independent measurements of total, elastic and inelastic cross-sections at $\sqrt{s}$ = 7 TeV
The TOTEM experiment at the LHC has performed the first luminosity-independent determination of the total proton-proton cross-section at . This technique is based on the optical theorem and requires simultaneous measurements of the inelastic rate – accomplished with the forward charged-particle telescopes T1 and T2 in the range 3.1 < |η| < 6.5 – and of the elastic rate by detecting the outcoming protons with Roman Pot detectors. The data presented here were collected in a dedicated run in 2011 with special beam optics (β* = 90 m) and Roman Pots approaching the beam close enough to register elastic events with squared four-momentum transfers |t| as low as 5·10−3 GeV2. The luminosity-independent results for the elastic, inelastic and total cross-sections are σel = (25.1 ± 1.1) mb, σinel = (72.9 ± 1.5) mb and σtot = (98.0 ± 2.5) mb, respectively. At the same time this method yields the integrated luminosity, in agreement with measurements by CMS. TOTEM has also determined the total cross-section in two complementary ways, both using the CMS luminosity measurement as an input. The first method sums the elastic and inelastic cross-sections and thus does not depend on the ρ parameter. The second applies the optical theorem to the elastic-scattering measurements only and therefore is free of the T1 and T2 measurement uncertainties. The methods, having very different systematic dependences, give results in excellent agreement. Moreover, the ρ-independent measurement makes a first estimate for the ρ parameter at possible: |ρ| = 0.145 ± 0.091.
114800615
The TOTEM Roman Pot Detector System at the LHC: Status, Operation and Performance
123310156
Status of the TOTEM experiment at LHC
The TOTEM experiment is dedicated to the measurement of the total proton–proton cross-section with the luminosity-independent method and the study of elastic and diffractive scattering processes. Two tracking telescopes, T1 and T2, integrated in the CMS detector, cover the pseudo-rapidity region between 3.1 and 6.5 on both sides of the interaction point IP5. The Roman Pot (RP) stations are located at distances of ±147 m and ±220 m with respect to the interaction point to measure the very forward scattered protons at very small angles. During the LHC technical stop in winter 2010/2011, the TOTEM experiment was completed with the installation of the T1 telescope and the RP stations at ±147 m. In 2011, the LHC machine provided special optics with the large s⁎=90 m, allowing TOTEM to measure the elastic scattering differential cross-section, down to the four-momentum transfer squared |t|=2×10−2 GeV2. Using the optical theorem and extrapolation of the differential cross-section to t  =0 (optical point), the total p–p cross-section at the LHC energy of s=7TeV could be computed for the first time. Furthermore we measured with standard LHC beam optics and the energy of s=7TeV the forward charged particle pseudorapidity density dn/dη in the range of 5.3<|η|<6.4. The status of the experiment, the performance of the detectors with emphasis on the RPs are described and the first physics results are presented.
125690152
The TOTEM experiment at LHC
The TOTEM experiment is dedicated to the measurement of the total proton-proton cross-section with the luminosity-independent method and the study of elastic and diffractive scattering processes. Two tracking telescopes, T1 and T2, integrated in the CMS detector, cover the pseudo-rapidity region between 3.1 and 6.5 on both sides of the interaction point IP5. The Roman Pot (RP) stations are located at distances of ± 147m and ± 220 m with respect to the interaction point to measure the very forward scattered protons at very small angles. During the LHC technical stop in winter 2010/2011, the TOTEM experiment was completed with the installation of the T1 telescope and the RP stations at ± 147 m. In 2011, the LHC machine provided special optics with the large s* = 90 m, allowing TOTEM to measure the elastic scattering differential cross section, down to the four-momentum transfer squared |t| = 2×10−2 GeV2. Using the optical theorem and extrapolation of the differential cross section to t = 0 (optical point), the total p-p cross section at the LHC energy of √v = 7 TeV could be computed for the first time. The status of the experiment, the performance of the detectors with emphasis on the RPs are described and the first physics results are presented.