A. David

Atmospheric aerosols exert an important influence on climate through their effects on stratiform cloud albedo and lifetime and the invigoration of convective storms. Model calculations suggest that almost half of the global cloud condensation nuclei in the atmospheric boundary layer may originate from the nucleation of aerosols from trace condensable vapours, although the sensitivity of the number of cloud condensation nuclei to changes of nucleation rate may be small. Despite extensive research, fundamental questions remain about the nucleation rate of sulphuric acid particles and the mechanisms responsible, including the roles of galactic cosmic rays and other chemical species such as ammonia. Here we present the first results from the CLOUD experiment at CERN. We find that atmospherically relevant ammonia mixing ratios of 100 parts per trillion by volume, or less, increase the nucleation rate of sulphuric acid particles more than 100-1,000-fold. Time-resolved molecular measurements reveal that nucleation proceeds by a base-stabilization mechanism involving the stepwise accretion of ammonia molecules. Ions increase the nucleation rate by an additional factor of between two and more than ten at ground-level galactic-cosmic-ray intensities, provided that the nucleation rate lies below the limiting ion-pair production rate. We find that ion-induced binary nucleation of H(2)SO(4)-H(2)O can occur in the mid-troposphere but is negligible in the boundary layer. However, even with the large enhancements in rate due to ammonia and ions, atmospheric concentrations of ammonia and sulphuric acid are insufficient to account for observed boundary-layer nucleation.

Nucleation of aerosol particles from trace atmospheric vapours is thought to provide up to half of global cloud condensation nuclei. Aerosols can cause a net cooling of climate by scattering sunlight and by leading to smaller but more numerous cloud droplets, which makes clouds brighter and extends their lifetimes. Atmospheric aerosols derived from human activities are thought to have compensated for a large fraction of the warming caused by greenhouse gases. However, despite its importance for climate, atmospheric nucleation is poorly understood. Recently, it has been shown that sulphuric acid and ammonia cannot explain particle formation rates observed in the lower atmosphere. It is thought that amines may enhance nucleation, but until now there has been no direct evidence for amine ternary nucleation under atmospheric conditions. Here we use the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber at CERN and find that dimethylamine above three parts per trillion by volume can enhance particle formation rates more than 1,000-fold compared with ammonia, sufficient to account for the particle formation rates observed in the atmosphere. Molecular analysis of the clusters reveals that the faster nucleation is explained by a base-stabilization mechanism involving acid-amine pairs, which strongly decrease evaporation. The ion-induced contribution is generally small, reflecting the high stability of sulphuric acid-dimethylamine clusters and indicating that galactic cosmic rays exert only a small influence on their formation, except at low overall formation rates. Our experimental measurements are well reproduced by a dynamical model based on quantum chemical calculations of binding energies of molecular clusters, without any fitted parameters. These results show that, in regions of the atmosphere near amine sources, both amines and sulphur dioxide should be considered when assessing the impact of anthropogenic activities on particle formation.

Atmospheric new-particle formation affects climate and is one of the least understood atmospheric aerosol processes. The complexity and variability of the atmosphere has hindered elucidation of the fundamental mechanism of new-particle formation from gaseous precursors. We show, in experiments performed with the CLOUD (Cosmics Leaving Outdoor Droplets) chamber at CERN, that sulfuric acid and oxidized organic vapors at atmospheric concentrations reproduce particle nucleation rates observed in the lower atmosphere. The experiments reveal a nucleation mechanism involving the formation of clusters containing sulfuric acid and oxidized organic molecules from the very first step. Inclusion of this mechanism in a global aerosol model yields a photochemically and biologically driven seasonal cycle of particle concentrations in the continental boundary layer, in good agreement with observations.

We report on a precision measurement of low-mass muon pairs in 158 AGeV indium-indium collisions at the CERN SPS. A significant excess of pairs is observed above the yield expected from neutral meson decays. The unprecedented sample size of 360,000 dimuons and the good mass resolution of about 2% allow us to isolate the excess by subtraction of the decay sources. The shape of the resulting mass spectrum is consistent with a dominant contribution from pi+pi- -->rho -->mu+mu- annihilation. The associated space-time averaged spectral function shows a strong broadening, but essentially no shift in mass. This may rule out theoretical models linking hadron masses directly to the chiral condensate.

A bstract The discovery by the ATLAS and CMS experiments of a new boson with mass around 125 GeV and with measured properties compatible with those of a Standard-Model Higgs boson, coupled with the absence of discoveries of phenomena beyond the Standard Model at the TeV scale, has triggered interest in ideas for future Higgs factories. A new circular e + e − collider hosted in a 80 to 100 km tunnel, TLEP, is among the most attractive solutions proposed so far. It has a clean experimental environment, produces high luminosity for top-quark, Higgs boson, W and Z studies, accommodates multiple detectors, and can reach energies up to the $$ \mathrm{t}\overline{\mathrm{t}} $$ threshold and beyond. It will enable measurements of the Higgs boson properties and of Electroweak Symmetry-Breaking (EWSB) parameters with unequalled precision, offering exploration of physics beyond the Standard Model in the multi-TeV range. Moreover, being the natural precursor of the VHE-LHC, a 100 TeV hadron machine in the same tunnel, it builds up a long-term vision for particle physics. Altogether, the combination of TLEP and the VHE-LHC offers, for a great cost effectiveness, the best precision and the best search reach of all options presently on the market. This paper presents a first appraisal of the salient features of the TLEP physics potential, to serve as a baseline for a more extensive design study.

This Report summarizes the results of the activities in 2012 and the first half of 2013 of the LHC Higgs Cross Section Working Group. The main goal of the working group was to present the state of the art of Higgs Physics at the LHC, integrating all new results that have appeared in the last few years. This report follows the first working group report Handbook of LHC Higgs Cross Sections: 1. Inclusive Observables (CERN-2011-002) and the second working group report Handbook of LHC Higgs Cross Sections: 2. Differential Distributions (CERN-2012-002). After the discovery of a Higgs boson at the LHC in mid-2012 this report focuses on refined prediction of Standard Model (SM) Higgs phenomenology around the experimentally observed value of 125-126 GeV, refined predictions for heavy SM-like Higgs bosons as well as predictions in the Minimal Supersymmetric Standard Model and first steps to go beyond these models. The other main focus is on the extraction of the characteristics and properties of the newly discovered particle such as couplings to SM particles, spin and CP-quantum numbers etc.

The NA60 experiment at the CERN SPS has studied low-mass muon pairs in 158AGeV In–In collisions. The mass and pT spectra associated with peripheral collisions can quantitatively be described by the known neutral meson decays. The high data quality has allowed to remeasure the electromagnetic transition form factors of the Dalitz decays η→μ+μ−γ and ω→μ+μ−π0. Using the usual pole approximation F=(1−M2/Λ2)−1 for the form factors, we find Λ−2 (in GeV−2) to be 1.95±0.17(stat.)±0.05(syst.) for the η and 2.24±0.06(stat.)±0.02(syst.) for the ω. While the values agree with previous results from the Lepton-G experiment, the errors are greatly improved, confirming now on the level of 10σ the strong enhancement of the ω form factor beyond the expectation from vector meson dominance. An improved value of the branching ratio BR(ω→μ+μ−π0)=[1.73±0.25(stat.)±0.14(syst.)]×10−4 has been obtained as a byproduct.

This Report summarizes the results of the activities of the LHC Higgs Cross Section Working Group in the period 2014-2016. The main goal of the working group was to present the state-of-the-art of Higgs physics at the LHC, integrating all new results that have appeared in the last few years. The first part compiles the most up-to-date predictions of Higgs boson production cross sections and decay branching ratios, parton distribution functions, and off-shell Higgs boson production and interference effects. The second part discusses the recent progress in Higgs effective field theory predictions, followed by the third part on pseudo-observables, simplified template cross section and fiducial cross section measurements, which give the baseline framework for Higgs boson property measurements. The fourth part deals with the beyond the Standard Model predictions of various benchmark scenarios of Minimal Supersymmetric Standard Model, extended scalar sector, Next-to-Minimal Supersymmetric Standard Model and exotic Higgs boson decays. This report follows three previous working-group reports: Handbook of LHC Higgs Cross Sections: 1. Inclusive Observables (CERN-2011-002), Handbook of LHC Higgs Cross Sections: 2. Differential Distributions (CERN-2012-002), and Handbook of LHC Higgs Cross Sections: 3. Higgs properties (CERN-2013-004). The current report serves as the baseline reference for Higgs physics in LHC Run 2 and beyond.

The NA60 experiment studies muon pair production at the CERN Super Proton Synchrotron. In this Letter we report on a precision measurement of J/ψ in In-In collisions. We have studied the J/ψ centrality distribution, and we have compared it with the one expected if absorption in cold nuclear matter were the only active suppression mechanism. For collisions involving more than ∼80 participant nucleons, we find that an extra suppression is present. This result is in qualitative agreement with previous Pb-Pb measurements by the NA50 experiment, but no theoretical explanation is presently able to coherently describe both results.Received 30 March 2007DOI:https://doi.org/10.1103/PhysRevLett.99.132302©2007 American Physical Society

The NA60 experiment at the CERN SPS has measured muon pairs with unprecedented precision in 158 A GeV In–In collisions. A strong excess of pairs above the known sources is observed in the whole mass region 0.2<M<2.6 GeV. The mass spectrum for M<1 GeV is consistent with a dominant contribution from π + π −→ρ→μ + μ − annihilation. The associated ρ spectral function shows a strong broadening, but essentially no shift in mass. For M>1 GeV, the excess is found to be prompt, not due to enhanced charm production, with pronounced differences to Drell–Yan pairs. The slope parameter T eff associated with the transverse momentum spectra rises with mass up to the ρ, followed by a sudden decline above. The rise for M<1 GeV is consistent with radial flow of a hadronic emission source. The seeming absence of significant flow for M>1 GeV and its relation to parton–hadron duality is discussed in detail, suggesting a dominantly partonic emission source in this region. A comparison of the data to the present status of theoretical modeling is also contained. The accumulated empirical evidence, including also a Planck-like shape of the mass spectra at low p T and the lack of polarization, is consistent with a global interpretation of the excess dimuons as thermal radiation. We conclude with first results on ω in-medium effects.

Abstract. During a 4-week run in October–November 2006, a pilot experiment was performed at the CERN Proton Synchrotron in preparation for the Cosmics Leaving OUtdoor Droplets (CLOUD) experiment, whose aim is to study the possible influence of cosmic rays on clouds. The purpose of the pilot experiment was firstly to carry out exploratory measurements of the effect of ionising particle radiation on aerosol formation from trace H2SO4 vapour and secondly to provide technical input for the CLOUD design. A total of 44 nucleation bursts were produced and recorded, with formation rates of particles above the 3 nm detection threshold of between 0.1 and 100 cm−3s−1, and growth rates between 2 and 37 nm h−1. The corresponding H2O concentrations were typically around 106 cm−3 or less. The experimentally-measured formation rates and H2SO4 concentrations are comparable to those found in the atmosphere, supporting the idea that sulphuric acid is involved in the nucleation of atmospheric aerosols. However, sulphuric acid alone is not able to explain the observed rapid growth rates, which suggests the presence of additional trace vapours in the aerosol chamber, whose identity is unknown. By analysing the charged fraction, a few of the aerosol bursts appear to have a contribution from ion-induced nucleation and ion-ion recombination to form neutral clusters. Some indications were also found for the accelerator beam timing and intensity to influence the aerosol particle formation rate at the highest experimental SO2 concentrations of 6 ppb, although none was found at lower concentrations. Overall, the exploratory measurements provide suggestive evidence for ion-induced nucleation or ion-ion recombination as sources of aerosol particles. However in order to quantify the conditions under which ion processes become significant, improvements are needed in controlling the experimental variables and in the reproducibility of the experiments. Finally, concerning technical aspects, the most important lessons for the CLOUD design include the stringent requirement of internal cleanliness of the aerosol chamber, as well as maintenance of extremely stable temperatures (variations below 0.1 °C

The yield of muon pairs in the invariant mass region 1<M<2.5 GeV/c 2 produced in heavy-ion collisions significantly exceeds the sum of the two expected contributions, Drell-Yan dimuons and muon pairs from the decays of D meson pairs. These sources properly account for the dimuons produced in proton-nucleus collisions. In this paper, we show that dimuons are also produced in excess in 158 A GeV In-In collisions. We furthermore observe, by tagging the dimuon vertices, that this excess is not due to enhanced D meson production, but made of prompt muon pairs, as expected from a source of thermal dimuons specific to high-energy nucleus-nucleus collisions. The yield of this excess increases significantly from peripheral to central collisions, both with respect to the Drell-Yan yield and to the number of nucleons participating in the collisions. Furthermore, the transverse mass distributions of the excess dimuons are well described by an exponential function, with inverse slope values around 190 MeV. The values are independent of mass and significantly lower than those found at masses below 1 GeV/c 2, rising there up to 250 MeV due to radial flow. This suggests the emission source of thermal dimuons above 1 GeV/c 2 to be of largely partonic origin, when radial flow has not yet built up.

The NA60 experiment at the CERN SPS has studied low-mass dimuon production in 158A GeV In-In collisions. An excess of pairs above the known meson decays has been reported before. We now present precision results on the associated transverse momentum spectra. The slope parameter Teff extracted from the spectra rises with dimuon mass up to the ρ, followed by a sudden decline above. While the initial rise is consistent with the expectations for radial flow of a hadronic decay source, the decline signals a transition to an emission source with much smaller flow. This may well represent the first direct evidence for thermal radiation of partonic origin in nuclear collisions.Received 26 June 2007DOI:https://doi.org/10.1103/PhysRevLett.100.022302©2008 American Physical Society

The world is embarking on a fast-track strategy to end the AIDS epidemic by 2030. UNAIDS is targeted towards achieving the 95-95-95 strategy by 2025. Scaling up prevention, testing and treatment services towards HIV/AIDS is paramount in achieving these targets. To understand the status of India in achieving these targets, review of trials registered in the CTRI registry was done and found that among the 155 included trials, most (n=45, 29%) of the trials were drug trails, few were vaccine trials (n=6, 3.8%). Out of 155 studies, forty-one (20%) were in line to reach UNAIDS’ targets. The primary focus of those studies was improving CD4 counts and suppression of viral load (third target of UNAIDS’) (n=12, 7.7%), and the minimal focus was on promoting treatment adherence (second target of UNAIDS’) (n=11, 7%) and promotion of HIV testing (first target of UNAIDS’) (n=4, 2.5%). As prevention is always better than care, research should be encouraged towards prevention of HIV, which in turn facilitates achieving UNAIDS’ 2025 and 2030 targets.

The NA60 experiment has measured muon pair production in In–In collisions at 158 AGeV at the CERN SPS. This paper presents a high statistics measurement of φ→μ μ meson production. Differential spectra, yields, mass and width are measured as a function of centrality and compared to previous measurements in other colliding systems at the same energy. The width of the rapidity distribution is found to be constant as a function of centrality, compatible with previous results. The decay muon polar angle distribution is measured in several reference frames. No evidence of polarization is found as a function of transverse momentum and centrality. The analysis of the p T spectra shows that the φ has a small radial flow, implying a weak coupling to the medium. The T eff parameter measured in In–In collisions suggests that the high value observed in Pb–Pb in the kaon channel is difficult to reconcile with radial flow alone. The absolute yield is compared to results in Pb–Pb collisions: though significantly smaller than measured by NA50 in the muon channel, it is found to exceed the NA49 and CERES data in the kaon channel at any centrality. The mass and width are found to be compatible with the PDG values at any centrality and at any p T : no evidence for in-medium modifications is observed.

The NA60 experiment studied low-mass muon pair production in proton-nucleus (p-A) collisions using a 400~GeV proton beam at the CERN SPS. The low-mass dimuon spectrum is well described by the superposition of the two-body and Dalitz decays of the light neutral mesons $\eta$, $\rho$, $\omega$, $\eta'$ and $\phi$, and no evidence of in-medium effects is found. A new high-precision measurement of the electromagnetic transition form factors of the $\eta$ and $\omega$ was performed, profiting from a 10~times larger data sample than the peripheral In-In sample previously collected by NA60. Using the pole-parameterisation $|F(M)|^2 = (1 -M^2/\mathrm{\Lambda}^2)^{-2}$ we find $\mathrm{\Lambda}_\eta^{-2} = 1.934\ \pm\ 0.067$~(stat.) $\pm\ 0.050$~(syst.)~(GeV/$c^2$)$^{-2}$ and $\mathrm{\Lambda}_\omega^{-2} = 2.223\ \pm\ 0.026$~(stat.) $\pm\ 0.037$~(syst.)~(GeV/$c^2$)$^{-2}$. An improved value of the branching ratio of the Dalitz decay $\omega \to \mu^+\mu^-\pi^0$ is also obtained, with $BR(\omega \to \mu^+\mu^-\pi^0) = [1.41~\pm~0.09~\mathrm{(stat.)}$ $\pm~0.15~\mathrm{(syst.)}] \times 10^{-4}$. Further results refer to the $\rho$ line shape and a new limit on $\rho/\omega$ interference in hadron interactions.

The LUX-ZEPLIN experiment recently reported limits on WIMP-nucleus interactions from its initial science run, down to 9.2 × 10 -48 cm 2 for the spin-independent interaction of a 36 GeV=c 2 WIMP at 90% confidence level.In this paper, we present a comprehensive analysis of the backgrounds important for this result and for other upcoming physics analyses, including neutrinoless double-beta decay searches and effective field theory interpretations of LUX-ZEPLIN data.We confirm that the in-situ determinations of bulk and fixed radioactive backgrounds are consistent with expectations from the ex-situ assays.The observed background rate after WIMP search criteria were applied was ð6.3 AE 0.5Þ × 10 -5 events=keV ee =kg=day in the low-energy region, approximately 60 times lower than the equivalent rate reported by the LUX experiment.

The LUX-ZEPLIN (LZ) experiment is a dark matter detector centered on a dual-phase xenon time projection chamber. We report searches for new physics appearing through few-keV-scale electron recoils, using the experiment's first exposure of 60 live days and a fiducial mass of 5.5 t. The data are found to be consistent with a background-only hypothesis, and limits are set on models for new physics including solar axion electron coupling, solar neutrino magnetic moment and millicharge, and electron couplings to galactic axionlike particles and hidden photons. Similar limits are set on weakly interacting massive particle (WIMP) dark matter producing signals through ionized atomic states from the Migdal effect.

The NA60 experiment has studied J/ψ production in p–A collisions at 158 and 400 GeV, at the CERN SPS. Nuclear effects on the J/ψ yield have been estimated from the A-dependence of the production cross section ratios σJ/ψA/σJ/ψBe (A = Al, Cu, In, W, Pb, U). We observe a significant nuclear suppression of the J/ψ yield per nucleon–nucleon collision, with a larger effect at lower incident energy, and we compare this result with previous observations by other fixed-target experiments. An attempt to disentangle the different contributions to the observed suppression has been carried out by studying the dependence of nuclear effects on x2, the fraction of the nucleon momentum carried by the interacting parton in the target nucleus.

This document presents an interim framework in which the coupling structure of a Higgs-like particle can be studied. After discussing different options and approximations, recommendations on specific benchmark parametrizations to be used to fit the data are given.

The problem of estimating the effect of missing higher orders in perturbation theory is analyzed with emphasis in the application to Higgs production in gluon–gluon fusion. Well-known mathematical methods for an approximated completion of the perturbative series are applied with the goal to not truncate the series, but complete it in a well-defined way, so as to increase the accuracy – if not the precision – of theoretical predictions. The uncertainty arising from the use of the completion procedure is discussed and a recipe for constructing a corresponding probability distribution function is proposed.

After the LHC Run 1, the standard model (SM) of particle physics has been completed. Yet, despite its successes, the SM has shortcomings vis-\`{a}-vis cosmological and other observations. At the same time, while the LHC restarts for Run 2 at 13 TeV, there is presently a lack of direct evidence for new physics phenomena at the accelerator energy frontier. From this state of affairs arises the need for a consistent theoretical framework in which deviations from the SM predictions can be calculated and compared to precision measurements. Such a framework should be able to comprehensively make use of all measurements in all sectors of particle physics, including LHC Higgs measurements, past electroweak precision data, electric dipole moment, $g-2$, penguins and flavor physics, neutrino scattering, deep inelastic scattering, low-energy $e^{+}e^{-}$ scattering, mass measurements, and any search for physics beyond the SM. By simultaneously describing all existing measurements, this framework then becomes an intermediate step, pointing us toward the next SM, and hopefully revealing the underlying symmetries. We review the role that the standard model effective field theory (SMEFT) could play in this context, as a consistent, complete, and calculable generalization of the SM in the absence of light new physics. We discuss the relationship of the SMEFT with the existing kappa-framework for Higgs boson couplings characterization and the use of pseudo-observables, that insulate experimental results from refinements due to ever-improving calculations. The LHC context, as well as that of previous and future accelerators and experiments, is also addressed.

Abstract As part of its HL-LHC upgrade program, the CMS collaboration is developing a High Granularity Calorimeter (CE) to replace the existing endcap calorimeters. The CE is a sampling calorimeter with unprecedented transverse and longitudinal readout for both electromagnetic (CE-E) and hadronic (CE-H) compartments. The calorimeter will be built with ∼30,000 hexagonal silicon modules. Prototype modules have been constructed with 6-inch hexagonal silicon sensors with cell areas of 1.1 cm 2 , and the SKIROC2-CMS readout ASIC. Beam tests of different sampling configurations were conducted with the prototype modules at DESY and CERN in 2017 and 2018. This paper describes the construction and commissioning of the CE calorimeter prototype, the silicon modules used in the construction, their basic performance, and the methods used for their calibration.

The NA60 experiment at the CERN SPS has studied low-mass muon pairs in 158 A GeV In–In collisions. A strong excess of pairs is observed above the yield expected from neutral meson decays. The unprecedented sample size close to 400000 events and the good mass resolution of about 2% made it possible to isolate the excess by subtraction of the decay sources. The shape of the resulting mass spectrum shows some non-trivial centrality dependence, but is largely consistent with a dominant contribution from π+π-→ϱ→μ+μ- annihilation. The associated ϱ spectral function exhibits considerable broadening, but essentially no shift in mass. The pT-differential mass spectra show the excess to be much stronger at low pT than at high pT. The results are compared to theoretical model predictions; they tend to rule out models linking hadron masses directly to the chiral condensate.

Calibration of the relative response of the individual channels of the barrel electromagnetic calorimeter of the CMS detector was accomplished, before installation, with cosmic ray muons and test beams. One fourth of the calorimeter was exposed to a beam of high energy electrons and the relative calibration of the channels, the intercalibration, was found to be reproducible to a precision of about 0.3%. Additionally, data were collected with cosmic rays for the entire ECAL barrel during the commissioning phase. By comparing the intercalibration constants obtained with the electron beam data with those from the cosmic ray data, it is demonstrated that the latter provide an intercalibration precision of 1.5% over most of the barrel ECAL. The best intercalibration precision is expected to come from the analysis of events collected in situ during the LHC operation. Using data collected with both electrons and pion beams, several aspects of the intercalibration procedures based on electrons or neutral pions were investigated.

Abstract The Compact Muon Solenoid collaboration is designing a new high-granularity endcap calorimeter, HGCAL, to be installed later this decade. As part of this development work, a prototype system was built, with an electromagnetic section consisting of 14 double-sided structures, providing 28 sampling layers. Each sampling layer has an hexagonal module, where a multipad large-area silicon sensor is glued between an electronics circuit board and a metal baseplate. The sensor pads of approximately 1.1 cm 2 are wire-bonded to the circuit board and are readout by custom integrated circuits. The prototype was extensively tested with beams at CERN's Super Proton Synchrotron in 2018. Based on the data collected with beams of positrons, with energies ranging from 20 to 300 GeV, measurements of the energy resolution and linearity, the position and angular resolutions, and the shower shapes are presented and compared to a detailed Geant4 simulation.

Searches for dark matter with liquid xenon time projection chamber experiments have traditionally focused on the region of the parameter space that is characteristic of weakly interacting massive particles, ranging from a few GeV/$c^2$ to a few TeV/$c^2$. Models of dark matter with a mass much heavier than this are well motivated by early production mechanisms different from the standard thermal freeze-out, but they have generally been less explored experimentally. In this work, we present a re-analysis of the first science run (SR1) of the LZ experiment, with an exposure of $0.9$ tonne$\times$year, to search for ultraheavy particle dark matter. The signal topology consists of multiple energy deposits in the active region of the detector forming a straight line, from which the velocity of the incoming particle can be reconstructed on an event-by-event basis. Zero events with this topology were observed after applying the data selection calibrated on a simulated sample of signal-like events. New experimental constraints are derived, which rule out previously unexplored regions of the dark matter parameter space of spin-independent interactions beyond a mass of 10$^{17}$ GeV/$c^2$.

Following the first science results of the LUX-ZEPLIN (LZ) experiment, a dual-phase xenon time projection chamber operating from the Sanford Underground Research Facility in Lead, South Dakota, USA, we report the initial limits on a model-independent nonrelativistic effective field theory describing the complete set of possible interactions of a weakly interacting massive particle (WIMP) with a nucleon. These results utilize the same 5.5 t fiducial mass and 60 live days of exposure collected for the LZ spin-independent and spin-dependent analyses while extending the upper limit of the energy region of interest by a factor of 7.5 to 270 keV. No significant excess in this high energy region is observed. Using a profile-likelihood ratio analysis, we report 90% confidence level exclusion limits on the coupling of each individual nonrelativistic WIMP-nucleon operator for both elastic and inelastic interactions in the isoscalar and isovector bases. Published by the American Physical Society 2024

The first science run of the LUX-ZEPLIN (LZ) experiment, a dual-phase xenon time project chamber operating in the Sanford Underground Research Facility in South Dakota, USA, has reported leading limits on spin-independent WIMP-nucleon interactions and interactions described from a non-relativistic effective field theory (NREFT). Using the same 5.5~t fiducial mass and 60 live days of exposure we report on the results of a relativistic extension to the NREFT. We present constraints on couplings from covariant interactions arising from the coupling of vector, axial currents, and electric dipole moments of the nucleon to the magnetic and electric dipole moments of the WIMP which cannot be described by recasting previous results described by an NREFT. Using a profile-likelihood ratio analysis, in an energy region between 0~keV$_\text{nr}$ to 270~keV$_\text{nr}$, we report 90% confidence level exclusion limits on the coupling strength of five interactions in both the isoscalar and isovector bases.

The NA60 experiment studies open charm and prompt dimuon production in proton–nucleus and nucleus–nucleus collisions at the CERN SPS. The high multiplicity of charged tracks produced in heavy-ion collisions imposes the use of silicon pixel detectors to perform an efficient tracking. This paper describes the design and assembly of the pixel telescope and performance results from three detector planes operated in the high charged particle multiplicity conditions of Pb–Pb collisions.

We estimate the amount of $^{37}$Ar produced in natural xenon via cosmic ray-induced spallation, an inevitable consequence of the transportation and storage of xenon on the Earth's surface. We then calculate the resulting $^{37}$Ar concentration in a 10-tonne payload~(similar to that of the LUX-ZEPLIN experiment) assuming a representative schedule of xenon purification, storage and delivery to the underground facility. Using the spallation model by Silberberg and Tsao, the sea level production rate of $^{37}$Ar in natural xenon is estimated to be 0.024~atoms/kg/day. Assuming the xenon is successively purified to remove radioactive contaminants in 1-tonne batches at a rate of 1~tonne/month, the average $^{37}$Ar activity after 10~tonnes are purified and transported underground is 0.058--0.090~$\mu$Bq/kg, depending on the degree of argon removal during above-ground purification. Such cosmogenic $^{37}$Ar will appear as a noticeable background in the early science data, while decaying with a 35~day half-life. This newly-noticed production mechanism of $^{37}$Ar should be considered when planning for future liquid xenon-based experiments.

J/ψ suppression has been studied by the NA60 experiment in Indium-Indium collisions. A new analysis technique, based only on the J/ψ sample, allows to accurately study the centrality dependence of J/ψ production. The observed pattern indicates that a suppression is already present in In-In collisions, setting in at ∼ 90 participant nucleons. A comparison with the available theoretical models is also presented.

The NA60 experiment at the CERN Super Proton Synchrotron has studied dimuon production in 158A GeV In-In collisions. The strong excess of pairs above the known sources found in the complete mass region 0.2<M<2.6 GeV has previously been interpreted as thermal radiation. We now present first results on the associated angular distributions. Using the Collins-Soper reference frame, the structure function parameters lambda, mu, and nu are measured to be zero, and the projected distributions in polar and azimuth angles are found to be uniform. The absence of any polarization is consistent with the interpretation of the excess dimuons as thermal radiation from a randomized system.

Ensuring the radiation hardness of PbWO4 crystals was one of the main priorities during the construction of the electromagnetic calorimeter of the CMS experiment at CERN. The production on an industrial scale of radiation hard crystals and their certification over a period of several years represented a difficult challenge both for CMS and for the crystal suppliers. The present article reviews the related scientific and technological problems encountered.

The NA60 experiment has studied low-mass muon pairs in 158 AGeV Indium-Indium collisions at the CERN SPS. A strong excess of pairs is observed above the expectation from neutral meson decays. The unprecedented sample size of 360 000 events and the good mass resolution of about 2% allow to isolate the excess by subtraction of the known sources. The shape of the resulting mass spectrum is consistent with a dominant contribution from π+π−→ρ→μ+μ− annihilation. The associated ρ spectral function shows a strong broadening, but essentially no shift in mass.

The NA60 experiment at the CERN SPS has studied low-mass muon pairs in 158 AGeV In–In collisions. A strong excess of pairs is observed above the yield expected from neutral meson decays. The unprecedented sample size of close to 400K events and the good mass resolution of about 2% have made it possible to isolate the excess by subtraction of the decay sources (keeping the ρ). The shape of the resulting mass spectrum exhibits considerable broadening, but essentially no shift in mass. The acceptance-corrected transverse-momentum spectra have a shape atypical for radial flow and show a significant mass dependence, pointing to different sources in different mass regions.

Abstract The CMS experiment at the CERN LHC will be upgraded to accommodate the 5-fold increase in the instantaneous luminosity expected at the High-Luminosity LHC (HL-LHC) [1]. Concomitant with this increase will be an increase in the number of interactions in each bunch crossing and a significant increase in the total ionising dose and fluence. One part of this upgrade is the replacement of the current endcap calorimeters with a high granularity sampling calorimeter equipped with silicon sensors, designed to manage the high collision rates [2]. As part of the development of this calorimeter, a series of beam tests have been conducted with different sampling configurations using prototype segmented silicon detectors. In the most recent of these tests, conducted in late 2018 at the CERN SPS, the performance of a prototype calorimeter equipped with ≈12,000 channels of silicon sensors was studied with beams of high-energy electrons, pions and muons. This paper describes the custom-built scalable data acquisition system that was built with readily available FPGA mezzanines and low-cost Raspberry Pi computers.

Abstract Wells drilled with nitrified drilling fluids require a solution for the transmission of measurement-while-drilling (MWD) surveys, bi-directional communication with rotary steerable systems, and transmission of MWD and and logging-while-drilling (LWD) measurements of downhole temperature and annular pressure for surface choke adjustments. Wired drillpipe (WDP) provides the solution for these requirements. Results from a recent well drilled into an underpressured reservoir in southern Mexico provided an opportunity to demonstrate the applicability of WDP to deliver the required measurements and maintain the proper directional control while keeping the well fluids under control. During WDP operations, both the traditional mud pulse transmission and the new WDP transmission methods are available, providing 100% reliability for receiving the downhole MWD/LWD data. During the drilling of this well, both single and multi-phase Managed Pressure Drilling (MPD) techniques were used. The plan called for the overburden and reservoir sections to be drilled in one bit run but with different mud types and constant bottomhole pressure (BHP). Before drilling the reservoir section, the single-phase mud used to drill the overburden had to be changed-over to multi-phase mud while monitoring the wellbore for signs of instability. Maintaining constant BHP in this type of MPD operation is complicated by the fact that current hydraulic models do not have the proven capability to support constant BHP in a nitrified OBM. With mud pulse telemetry, downhole data transmission stops when the rig pumps are shut-down. But with WDP, downhole data is actively transmitted during the time between pump shut-down and pipe disconnection. This allows MPD personnel to monitor actual annular pressure during pump transitions and more accurately determine the optimum choke position for constant BHP. During the connection, the downhole annular pressure is stored in memory. Once the connection has been made the data is transmited up-hole for evaluation and analysis, which provides immediate feedback on the stability of the BHP during the connection. Pressure sensors (along string measurements or ASM) within the multiple WDP repeater subs allow us to compute the fluid density at multiple intervals along the annulus for the first time in the history of drilling. We document a rather surprising case of temperature effects overriding pressure effects during the use of a single-phase compressible OBM used in the first stage of this drilling operation. This has implications for using WDP measurements to calibrate and verify hydraulic models for both single and multi-phase drilling fluids. Proper hydraulic modeling capabilities are critical for MPD operations. This well provides the opportunity to demonstrate other applications for these newly invented "interval fluid densities." For example, they are used to verify the top of the fluid level with and without the presence of nitrogen injection when accurate flow-in versus flow-out measurements are not available. This is used to verify the presence or absence of lost circulation and formation fluid influx during MPD operations, which is very difficult otherwise. WDP allows for the transmission of high-frequency vibration and collar rotation data from the bottomhole assembly (BHA). This is used to determine the dynamic rotational tendencies of this drillstring under varying conditions, which can then be used to calibrate a dynamic mathematical drillstring model. This is then used to predict optimum drilling parameters to minimize stick/slip, bit bounce, and bit whirl to optimize rate of penetration (ROP).

The performance of electromagnetic calorimeter modules made of proton-irradiated PbWO4 crystals has been studied in beam tests. The modules, similar to those used in the Endcaps of the CMS electromagnetic calorimeter (ECAL), were formed from 5×5 matrices of PbWO4 crystals, which had previously been exposed to 24 GeV protons up to integrated fluences between 2.1× 1013 and 1.3× 1014 cm−2. These correspond to the predicted charged-hadron fluences in the ECAL Endcaps at pseudorapidity η = 2.6 after about 500 fb−1 and 3000 fb−1 respectively, corresponding to the end of the LHC and High Luminosity LHC operation periods. The irradiated crystals have a lower light transmission for wavelengths corresponding to the scintillation light, and a correspondingly reduced light output. A comparison with four crystals irradiated in situ in CMS showed no significant rate dependence of hadron-induced damage. A degradation of the energy resolution and a non-linear response to electron showers are observed in damaged crystals. Direct measurements of the light output from the crystals show the amplitude decreasing and pulse becoming faster as the fluence increases. The latter is interpreted, through comparison with simulation, as a side-effect of the degradation in light transmission. The experimental results obtained can be used to estimate the long term performance of the CMS ECAL.

Using the likelihood ratio test statistic, we present a method which can be employed to test the hypothesis of a single Higgs boson using the matrix of measured signal strengths. This method can be applied in the presence of incomplete data and takes into account uncertainties on the measurements. The p-value against the hypothesis of a single Higgs boson is defined from the expected distribution of the test statistic, generated using pseudo-experiments. The applicability of the likelihood-based test is demonstrated using numerical examples with uncertainties and missing matrix elements.

We present preliminary results on the production of intermediate mass dimuons in 158 A⋅GeV In-In collisions at the CERN SPS. NA38 and NA50 observed a strong excess in this region in S-U and Pb-Pb interactions with respect to the dimuon production rate expected from p-A data. Thanks to the use of a pixel vertex telescope, NA60 can separate the prompt dimuons from the pairs resulting from open charm decays and show that the excess dimuons are of prompt origin.

Heavy quark effective theory predicts that produced charm quarks have the same probability to fragment into any of the four D mesons with orbital angular momentum L=0: the singlet D state and the triplet D∗ states. This would imply PV(D∗,D)=3/4, where PV is the ratio between directly produced L=0 vector states (D∗) and all L=0 (D and D∗) states. Experimental data collected in several different collision systems (e+e−, hadro-production, photo-production, etc.) and over a broad range of collision energies, show that PV(D∗,D)=0.594±0.010. From this observation, it follows that “naive spin counting” does not apply to charm production, implying a revision of charm production calculations where this assumption is made.

The NA60 experiment at the CERN SPS has studied ϕ meson production in In–In collisions at 158 A GeV via both the K+K− and the μ+μ− decay channels. The yields and inverse slope parameters of the mT spectra observed in the two channels are compatible within errors, different from the large discrepancies seen in Pb–Pb collisions between the hadronic (NA49) and dimuon (NA50) decay channels. Possible physics implications are discussed.

Backplane buses are becoming a legacy for high-rate, high-volume data processing applications. Higher efficiency at lower cost is offered by the PCI bus technology, compared to crate-embedded processors. Becoming part of the plug and play domain of the host's operating system, no additional data transfer protocols are needed. We have combined PCI technology with high-density field-programmable gate array (FPGA) logic and common mezzanine standards on a flexible PCI card. First applications cover readout controllers for legacy bus protocols, high-speed link I/O and fast analog input data conversion. An FPGA with embedded PCI master/target core serves as a programmable interface between the PCI bus, mezzanine cards, and a local SDRAM. Adapter mezzanine cards, implemented according to the IEEE P1386 or similar common standards, are used for voltage level conversion, trigger interfacing or preprocessing. The application-dependent controller functions as well as SDRAM and PCI interfacing are handled by FPGA logic. A Linux driver was developed to achieve high bandwidth via CPU-initiated transfers. Control software for Windows and an interface for LabView target control and monitoring applications via graphical interfaces. First experience and applications are reported.

The NA60 experiment has measured the production of muon pairs and charged particles in In+In collisions at a beam energy of 158 A GeV. For invariant dimuon masses below the ϕ, the spacetime averaged ρ spectral function was isolated by a novel procedure. It shows a strong broadening but essentially no shift in mass. The production of J/ψ was measured as a function of the collision centrality. As in previous experiments studying Pb+Pb collisions an anomalous suppression is observed, setting in at approximately 90 participant nucleons. Using the charged particles, the reaction plane was reconstructed. The elliptic flow of charged particles increases with pt showing a saturation for pt > 2 GeV/c. For the first time, azimuthal distributions for J/ψ are shown.

This Report summarizes the results of the activities of the LHC Higgs Cross Section Working Group in the period 2014-2016. The main goal of the working group was to present the state-of-the-art of Higgs physics at the LHC, integrating all new results that have appeared in the last few years. The first part compiles the most up-to-date predictions of Higgs boson production cross sections and decay branching ratios, parton distribution functions, and off-shell Higgs boson production and interference effects. The second part discusses the recent progress in Higgs effective field theory predictions, followed by the third part on pseudo-observables, simplified template cross section and fiducial cross section measurements, which give the baseline framework for Higgs boson property measurements. The fourth part deals with the beyond the Standard Model predictions of various benchmark scenarios of Minimal Supersymmetric Standard Model, extended scalar sector, Next-to-Minimal Supersymmetric Standard Model and exotic Higgs boson decays. This report follows three previous working-group reports: Handbook of LHC Higgs Cross Sections: 1. Inclusive Observables (CERN-2011-002), Handbook of LHC Higgs Cross Sections: 2. Differential Distributions (CERN-2012-002), and Handbook of LHC Higgs Cross Sections: 3. Higgs properties (CERN-2013-004). The current report serves as the baseline reference for Higgs physics in LHC Run 2 and beyond.

Abstract The NA60 experiment studies the production of open charm and prompt dimuons in proton–nucleus and nucleus–nucleus collisions at the CERN SPS. To access the kinematics of charged particles already at the vertex level, a radiation tolerant silicon pixel detector has been placed in a 2.5 T magnetic field near the target. This vertex spectrometer was built from 96 ALICE1LHCB pixel chips arranged in 12 tracking planes. The vertex spectrometer was successfully operated in a run with a 158 GeV/nucleon indium ion beam incident on indium targets in October–November 2003. During the five-week-long run it was exposed to high levels of radiation distributed inhomogeneously over the detector. The most exposed regions of the silicon sensors underwent type inversion. With only a fraction of the total statistics analysed, the vertex spectrometer can already be seen to have dramatically enhanced the physics performance of NA60 with respect to that of its predecessors.

The NA60 experiment studies the production of open charm and prompt dimuons in proton–nucleus and nucleus–nucleus collisions at the CERN SPS. The main goal of NA60 is the study of various possible signatures of the transition from hadronic to deconfined partonic matter, e.g. anomalous charmonium suppression, dimuons from thermal radiation and modifications of vector meson properties. Reaching these goals is facilitated by the use of new state-of-the-art silicon detectors in the vertex region. Downstream of the target and inside a 2.5 T dipole magnetic field a pixel telescope measures the charged tracks originating from the collisions. The full pixel telescope consists of 16 planes with 96 ALICE1LHCb pixel detector assemblies in total. This paper describes the setup of the pixel telescope, results from tests as well as the expected implications of the operation of the silicon detectors in the harsh radiation environment of the NA60 experiment, with heavy-ion collisions.

The NA60 experiment at the CERN SPS studies dimuon production in nucleusnucleus and proton-nucleus collisions. One of the main detectors in the apparatus is the silicon pixel vertex telescope, which tracks charged particles in the target region. This detector complements the information from the muon spectrometer, improving the dimuon mass resolution and signal-to-noise ratio of the experiment, overcoming the main limitations of its predecessors.

Abstract. During a 4-week run in October–November 2006, a pilot experiment was performed at the CERN Proton Synchrotron in preparation for the CLOUD1 experiment, whose aim is to study the possible influence of cosmic rays on clouds. The purpose of the pilot experiment was firstly to carry out exploratory measurements of the effect of ionising particle radiation on aerosol formation from trace H2SO4 vapour and secondly to provide technical input for the CLOUD design. A total of 44 nucleation bursts were produced and recorded, with formation rates of particles above the 3 nm detection threshold of between 0.1 and 100 cm−3s−1, and growth rates between 2 and 37 nm h−1. The corresponding H2SO4 concentrations were typically around 106 cm−3 or less. The experimentally-measured formation rates and H2SO4 concentrations are comparable to those found in the atmosphere, supporting the idea that sulphuric acid is involved in the nucleation of atmospheric aerosols. However, sulphuric acid alone is not able to explain the observed rapid growth rates, which suggests the presence of additional trace vapours in the aerosol chamber, whose identity is unknown. By analysing the charged fraction, a few of the aerosol bursts appear to have a contribution from ion-induced nucleation and ion-ion recombination to form neutral clusters. Some indications were also found for the accelerator beam timing and intensity to influence the aerosol particle formation rate at the highest experimental SO2 concentrations of 6 ppb, although none was found at lower concentrations. Overall, the exploratory measurements provide suggestive evidence for ion-induced nucleation or ion-ion recombination as sources of aerosol particles. However in order to quantify the conditions under which ion processes become significant, improvements are needed in controlling the experimental variables and in the reproducibility of the experiments. Finally, concerning technical aspects, the most important lessons for the CLOUD design include the stringent requirement of internal cleanliness of the aerosol chamber, as well as maintenance of extremely stable temperatures (variations below 0.1°C). 1CLOUD is an acronym of Cosmics Leaving OUtdoor Droplets.

The NA60 experiment studies muon pair production with proton and Indium beams. It is a second generation experiment, designed to answer specific questions left open, in the leptonic sector, by the previous round of SPS experiments, finished in 2000. The results presented in this paper cover the dimuon invariant mass range from the threshold to the J/ ψ . The main physics topics that we address include the in-medium modifications of the ρ meson, the origin of the dimuon excess observed between the ϕ and the J/ ψ , and the study of the anomalous J/ ψ suppression. For each of these subjects, the NA60 results represent a significant step forward towards a deeper understanding of the physics of heavy ion collisions at SPS energies.

The LUX-ZEPLIN (LZ) experiment is a dark matter detector centered on a dual-phase xenon time projection chamber. We report searches for new physics appearing through few-keV-scale electron recoils, using the experiment's first exposure of 60 live days and a fiducial mass of 5.5t. The data are found to be consistent with a background-only hypothesis, and limits are set on models for new physics including solar axion electron coupling, solar neutrino magnetic moment and millicharge, and electron couplings to galactic axion-like particles and hidden photons. Similar limits are set on weakly interacting massive particle (WIMP) dark matter producing signals through ionized atomic states from the Migdal effect.

Following the first science results of the LUX-ZEPLIN (LZ) experiment, a dual-phase xenon time projection chamber operating from the Sanford Underground Research Facility in Lead, South Dakota, USA, we report the initial limits on a model-independent non-relativistic effective field theory describing the complete set of possible interactions of a weakly interacting massive particle (WIMP) with a nucleon. These results utilize the same 5.5 t fiducial mass and 60 live days of exposure collected for the LZ spin-independent and spin-dependent analyses while extending the upper limit of the energy region of interest by a factor of 7.5 to 270 keVnr. No significant excess in this high energy region is observed. Using a profile-likelihood ratio analysis, we report 90% confidence level exclusion limits on the coupling of each individual non-relativistic WIMP-nucleon operator for both elastic and inelastic interactions in the isoscalar and isovector bases.

The NA60 experiment was designed to identify signatures of a new state of matter, the Quark Gluon Plasma, in heavy-ion collisions at the CERN Super Proton Synchroton.The apparatus is composed of four main detectors: a muon spectrometer (MS), a zero degree calorimeter (ZDC), a silicon vertex telescope (VT), and a silicon microstrip beam tracker (BT).The readout of the whole experiment is based on a PCI architecture.The basic unit is a general purpose PCI card, interfaced to the different subdetectors via custom mezzanine cards.This allowed us to successfully implement several completely different readout protocols (from the VME like protocol of the MS to the custom protocol of the pixel telescope).The system was fully tested with proton and ion beams, and several million events were collected in 2002 and 2003.This paper presents the readout architecture of NA60, with particular emphasis on the PCI layer common to all the subdetectors.

Recently, some high energy physics experiments have started to adopt readout systems based on the PCI architecture. In this context, a new PCI card that can be adapted to several readout schemes has been designed. It contains a 64-MiB local buffer, programmable FPGA logic, a hardware PCI bridge, and can be connected to mezzanine cards. The card is presently used in the NA60 experiment at the CERN SPS for the readout of several detectors. The interfacing to the different front-ends is provided by the mezzanine cards while the readout protocols are implemented in the FPGA. Moreover, it is used as a test readout system for the ALICE experiment muon chambers. This paper describes the card, with particular emphasis on its flexibility and relatively simple development, related to the use of an external PCI bridge.

NA60 is a fixed-target experiment at the CERN SPS which measured dimuon production in nucleus–nucleus and proton–nucleus collisions. The experiment collected muon pair samples of unprecedented quality in heavy-ion experiments. This paper presents a high quality measurement of the pT distribution of the φ meson, covering a broad pT window. The data were collected in 2003 in In-In collisions at 158 GeV per nucleon. The results, presented as a function of centrality, were studied against several possible sources of systematic effects and proved to be fairly stable. We show that the inverse mT slope measured in In-In collisions, in the φ→μμ decay channel, depends significantly on the range used to perform the fit. When the fit is performed at low transverse momentum, the effective inverse slope increases from peripheral to central collisions, as measured by other experiments. We finally show that our measurement for In-In is compatible with the overall systematics of T slope versus mass, measured in different collision systems by the NA49 experiment

NA60 is taking data with proton and heavy-ion beams at the CERN SPS. Although building up on previous experiments, the dimuon physics programme of NA60 places very demanding requirements on its new detectors, in terms of radiation tolerance, granularity and read-out electronics speed. We start by comparing dimuon detection strategies in NA60 with those of previous experiments. We then describe the new detectors used in NA60, placing particular emphasis on their technological pioneering aspects as well as on their contributions to the overall physics performance of the experiment.

The silicon microstrip telescope is a key detector of the NA60 experiment when taking data with proton beams at the CERN SPS. After an overview of the architecture underlying its readout electronics, we describe the individual components in the system. We then analyze the system performance and conclude by commenting on its operation.

The NA60 experiment studied ϕ meson production in p-A and In-In collisions at the CERN SPS. The ratio ϕ/ω shows an increase by a factor ∼2 from peripheral to central collisions. The inverse slope parameter T of the pT spectrum increases with centrality, and seems to agree with the previous NA49 measurements.

The NA60 experiment at the CERN SPS studies dimuon production in proton and heavy ion collisions. Its silicon pixel vertex telescope allows tracking of muon pairs in the vertex region, complementing the information from the muon spectrometer, and improving the mass resolution and signal-to-noise ratio. First results from the In-In data taking are shown for the light resonances and the J/ψ meson production.

The NA60 experiment is taking place at the CERN SPS, to study the production of open charm and of prompt dimuons in collisions induced by proton and heavy ion beams on nuclear targets. In this paper we will present an overview of the detector concept, followed by a description of the newly developed silicon vertex telescope and its performance. Then we present some first results, including a dimuon mass spectrum obtained using the silicon vertex telescope.

The NA60 experiment at the CERN SPS studied phi production in In–In collisions at 158 A GeV via muon and kaon decay channels. The yields and transverse mass spectra observed in the two channels are compatible within errors. The results are compared to the previous measurements in Pb–Pb collisions, where large discrepancies were observed between NA50 (muon pairs) and NA49 (kaon pairs).

NA60 measured dimuon production in p-A and In-In collisions at the CERN SPS. This paper presents a high statistics measurement of $\phi$ meson production in In-In collisions at 158 AGeV. Both the transverse momentum, rapidity, decay angular distributions and the absolute yield were measured as a function of centrality. The results are compared to previous measurements in order to shed light on the long standing $\phi$ puzzle. In addition, highlights on $\eta$ meson production and on the dimuon excess below the J/$\psi$ mass are presented.

The CMS experiment uses information from its electromagnetic and hadronic calorimeters and muon detectors to decide whether to readout the whole detector. For such a task to be successful, all trigger primitives pushed through the trigger decision tree must be flawlessly aligned in time for operation at 40 MHz. Both calorimeters in CMS use the Synchronization Link Board for this purpose. In this article we report on the results of tests of this board using realistic beam conditions, which demonstrate the soundness of the adopted architecture and synchronization principle.

The NA60 experiment is a fixed-target experiment at the CERN SPS. It has measured the dimuon yield in Indium--Indium collisions with an In beam of 158 AGeV/c and in p-A collisions with a proton beam of 400 and 158 AGeV/c. The results allow to address three important physics topics, namely the study of the rho spectral function in nuclear collisions, the clarification of the origin of the dimuon excess measured by NA50 in the intermediate mass range, and the J/psi suppression pattern in a collision system different from Pb-Pb. An overview of these results will be given in this paper.

In this work we address three questions: can we successfully describe (observed) deviations from the standard model in the SMEFT language? Can we learn something about the underlying, beyond the standard model, physics using the SMEFT language? If no deviation is observed, how to proceed? Given the myriad of viable BSM options with extended scalar sectors, we suggest a widespread use of SMEFT not just as a global fitting tool (that could miss out on deviations from extended scalar sectors) but also as a bookkeeping framework in which the results from SMEFT fits to individual observables are provided, reported, and archived in a consistent way. The compatibility of such individual results can then be assessed in the light of BSM models with extended scalar sectors.

The NA60 experiment has studied low-mass muon pair production in proton–nucleus collisions with a system of Be, Cu, In, W, Pb and U targets, using a 400 GeV proton beam at the CERN SPS. The transverse momentum spectra of the $$\rho /\omega $$ and $$\phi $$ mesons are measured in the full $$p_{\mathrm {T}}$$ range accessible, from $$p_{\mathrm {T}}= 0$$ up to $$2 \, {\hbox {GeV/c}}$$ . The nuclear dependence of the production cross sections of the $$\eta $$ , $$\omega $$ and $$\phi $$ mesons has been found to be consistent with the power law $$\sigma _{\mathrm {pA}} \propto {\mathrm {A}}^\alpha $$ , with the $$\alpha $$ parameter increasing as a function of $$p_{\mathrm {T}}$$ for all the particles, and an approximate hierarchy $$\alpha _\eta \approx \alpha _\phi > \alpha _\omega $$ . The cross section ratios $$\sigma _\eta /\sigma _\omega $$ , $$\sigma _\rho /\sigma _\omega $$ and $$\sigma _\phi /\sigma _\omega $$ have been studied as a function of the size A of the production target, and an increase of the $$\eta $$ and $$\phi $$ yields relative to the $$\omega $$ is observed from p–Be to p–U collisions.

Abstract NA60 is a fixed target experiment at the CERN SPS designed to study the production of open charm and prompt dimuons in proton–nucleus and heavy-ion collisions. To access the kinematics of the charged particles produced in the collisions already at the vertex level, a vertex telescope made from radiation-tolerant silicon pixel detectors has been placed inside a 2.5 T magnetic field close to the target. In 2003 the vertex spectrometer, made from 12 tracking planes with 96 ALICE1LHCb pixel chips, was successfully operated in a run with a 158 GeV/nucleon indium ion beam incident on indium targets. During the five weeks of data taking, the detector was exposed to high and inhomogeneously distributed radiation levels. For the 2004 proton run, the telescope was upgraded with ATLAS pixel detector modules to cope with the higher interaction rates in this run. This paper describes the setup of the pixel telescope and summarises results concerning detector performance and radiation damage.

Abstract NA60 is a fixed target experiment at the CERN SPS designed to study the production of open charm and prompt dimuons in proton–nucleus and heavy-ion collisions. To access the kinematics of the charged particles produced in the collisions already at the vertex level, a tracker made from radiation-tolerant silicon pixel detectors has been placed inside a 2.5 T magnetic field close to the target. In 2003 the vertex spectrometer, made from 12 tracking planes with 96 ALICE1LHCb pixel chips, was successfully operated in a run with a 158 GeV/nucleon indium ion beam incident on indium targets. During the five weeks of data taking, the detector was exposed to high and inhomogeneously distributed radiation levels. For the 2004 proton run, the tracker was upgraded with ATLAS pixel detector modules, to allow higher interaction rates. This paper describes the setup of the pixel tracker, its performance and the radiation damage it suffered.

The NA60 experiment at the CERN SPS studies dimuon production in nucleus-nucleus and proton-nucleus collisions. The NA60 experimental program requires accurate tracking in the vertex region. In particular, it is crucial to distinguish between dimuons coming from the interaction vertex and muon pairs coming from the decay of charmed mesons. The high multiplicity of charged tracks produced in heavy-ion collisions imposes the use of radiation tolerant silicon pixel detectors. The NA60 silicon vertex detector is made of 16 planes, providing 11 tracking points. It was commissioned in the summer of 2003 and used in a 40-day-long data taking period in October/November 2003. This paper describes the detector, its performance and results from the 2003 Indium-Indium run.

The NA60 experiment at the CERN SPS studies the production of open charm and prompt dimuons in collisions induced by proton and heavy ion beams on nuclear targets. The experimental setup includes a silicon vertex telescope, placed inside a dipole magnetic field, to match charged particle tracks with the muon tracks measured by a muon spectrometer. In p-A collisions the vertex telescope is mostly made of silicon microstrip planes, whereas in A-A interactions the higher multiplicity imposes the use of high granularity silicon pixel detectors. The high interaction rate required for the study of rare processes imposes the use of radiation tolerant pixel detectors. NA60 took its first data in the year 2002, with 400 GeV protons and with Pb ions of 20 and 30 GeV per nucleon. The proton data have been used for the study of dimuon production, while the heavy ion data were devoted to the commissioning of the pixel detectors and to the study of charged particle pseudorapidity densities. After an overview of the detector concept, this paper presents the first results obtained with the 2002 data.

Using the likelihood ratio test statistic, we present a method which can be employed to test the hypothesis of a single Higgs boson using the matrix of measured signal strengths. This method can be applied in the presence of incomplete data and takes into account uncertainties on the measurements. The p-value against the hypothesis of a single Higgs boson is defined from the expected distribution of the test statistic, generated using pseudo-experiments. The applicability of the likelihood-based test is demonstrated using numerical examples with uncertainties and missing matrix elements.

The CLOUD data acquisition, online data analysis and control system, address the challenges of online monitoring, control and data plotting, while providing a centralized data repository with unified tools for data access and visualization. The system was optimized for rapid instrument integration and flexible data format processing. It was built upon open architecture components including a computing cluster monitoring and an open database management system. The different approaches for parameter computation available in the CLOUD central data acquisition system are explained.

June 2011%%%%Thesis by publication.%%%%%%%%%%%%1. Introduction  – 2. Data and methods  – 3. Global patterns of NPP  – 4. Global proapting interannual features of Chl  – 5. South Hemisphere interannual patterns of Chl  – 6. Tropical and South Pacific seasonality  – 7. Tropical and South Pacific ENSO propagating variability  – 8. EAC patterns of Chl  – 9. General discussion and conclusions.%%%%Phytoplankton are a unique group of organisms, mostly due to their exclusive capacity to photosynthesise inorganic matter into highly energetic organic compounds. Consequently phytoplankton growth, i.e., primary productivity, fuels almost all life in the global ocean and plays a crucial role in biogeochemical cycles and climate processes. Although it is commonly known that phytoplankton primary productivity is highly variable at intra-annual scales, inter-annual patterns of variability have only relatively recently been observed with the advent of remote sensing technology. Satellite instruments detect and estimate chlorophyll, a molecule present in all phytoplankton, and primary productivity rates, at a global scale. Here, we use remote sensing products to assess net primary productivity and surface chlorophyll-a patterns of variability from intra- to multi-annual, and global to regional scales, and evaluate its physical forcing mechanisms. We aim to assess the connections between large-scale climate variability and inter- and multi-annual phytoplankton patterns of variability via empirical analysis of satellite derived Chl and various geophysical parameters. The main methodology utilised to this end is the Empirical Orthogonal Function (EOF) for detecting standing signals and its extended form to isolate propagating features. Our findings include a much higher percentage of NPP variability at seasonal scales (~90%) than previously acknowledged, an anomalous change of 90 Pg.C (Pg = 1015g) in the last decade coupled to the classic El Nino - Southern Oscillation (ENSO) regional climate phenomenon, and an extra 18 Pg.C fixed in the ocean which can be attributed to the influence of the past decade's trend found in a controversial second main mode of variability. Further, we use extended EOF (EEOF) to isolate and analyse propagating features of surface chlorophyll-a across the global ocean and link them to regional climate modes of variability. We then focus on the Tropical and South Pacific regions, characterizing the seasonal atmosphere and ocean dynamics and isolating the regional propagating inter-annual features. Finally, we assess the influence of the East Australian Current on regional remotely sensed chlorophyll, and investigate the role of large-scale regional climate modes of variability on chlorophyll patterns.%%%%%%%%1 online resource (x, 207 pages) illustrations, maps

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The CMS detector at LHC is equipped with a high precision lead tungstate crystal electromagnetic calorimeter (ECAL). The front-end boards and the photodetectors are monitored using a network of DCU (Detector Control Unit) chips located on the detector electronics. The DCU data are accessible through token rings controlled by an XDAQ-based software component. Relevant parameters are transferred to DCS (Detector Control System) and stored into the Condition DataBase. The operational experience from the ECAL commissioning at the CMS experimental cavern is discussed and summarized.

In this paper we give a description of the database services for the control and monitoring of the electromagnetic calorimeter of the CMS experiment at LHC. After a general description of the software infrastructure, we present the organization of the tables in the database, that has been designed in order to simplify the development of software interfaces. This feature is achieved including in the database the description of each relevant table. We also give some estimation about the final size and performance of the system.

The LHC will collide protons at √s = 14 TeV and lead beams at √sNN = 5.5 TeV as well as possibly other AA and pA combinations. The physics program of the Compact Muon Solenoid (CMS) includes the study of heavy-ion collisions, where the collision energy, higher than at RHIC, will allow the study of the dense partonic system with hard probes. A broad palette of these probes is within the reach of CMS. Some are likely to be modified, relative to p-p collisions, by the presence of the hot medium, like quarkonia (J/ψ and γ) or high-pT jets. Others, like heavy quarks, Z0 bosons and photons, will act as reference candles. This article overviews the hard physics reach and unique abilities of CMS in studying the medium produced in heavy-ion collisions at the LHC.

The CMS experiment uses information from its electromagnetic and hadronic calorimeters and muon detectors to decide whether to read out the whole detector. For such a task to be successful, all trigger primitives pushed through the trigger decision tree must be flawlessly aligned in time for operation at 40 MHz. Both calorimeters in CMS use the Synchronization Link Board for this purpose. In this article we report on the test results of this board using the bunched beams available in the H4 electron beam line at CERN.