Vieri Candelise

A common library, TMDlib2, for Transverse-Momentum-Dependent distributions (TMDs) and unintegrated parton distributions (uPDFs) is described, which allows for easy access of commonly used TMDs and uPDFs, providing a three-dimensional (3D) picture of the partonic structure of hadrons. The tool TMDplotter allows for web-based plotting of distributions implemented in TMDlib2, together with collinear pdfs as available in LHAPDF.

The High Luminosity phase of the Large Hadron Collider will deliver 10 times more integrated luminosity than the existing collider, posing significant challenges for radiation tolerance and event pileup on detectors, especially for forward calorimetry. As part of its upgrade program, the Compact Muon Solenoid collaboration is designing a high-granularity calorimeter (HGCAL) to replace the existing endcap calorimeters. It will feature unprecedented transverse and longitudinal readout and triggering segmentation for both electromagnetic and hadronic sections. The electromagnetic section and a large fraction of the hadronic section will be based on hexagonal silicon sensors of 0.5–1 cm2 cell size, with the remainder of the hadronic section being based on highly-segmented scintillators with silicon photomultiplier readout. The intrinsic high-precision timing capabilities of the silicon sensors will add an extra dimension to event reconstruction, especially in terms of pileup rejection. First hexagonal silicon modules, using the existing Skiroc2 front-end ASIC developed for CALICE, have been tested in beams at Fermilab and CERN in 2016. We present results from these tests, in terms of system stability, calibration with minimum-ionizing particles and resolution (energy, position and timing) for electrons, and the comparisons of these quantities with GEANT4-based simulation.

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.

A sampling calorimeter using cerium fluoride scintillating crystals as active material, interleaved with heavy absorber plates, and read out by wavelength-shifting (WLS) fibers is being studied as a calorimeter option for detectors at the upgraded High-Luminosity LHC (HL-LHC) collider at CERN. A prototype has been exposed to electron beams of different energies at the INFN Frascati (Italy) Beam Test Facility. This paper presents results from the studies performed on the prototype, such as signal amplitudes, light yield and energy resolution.

A prototype for a sampling calorimeter made out of cerium fluoride crystals interleaved with tungsten plates, and read out by wavelength-shifting fibres, has been exposed to beams of electrons with energies between 20 and 150 GeV, produced by the CERN Super Proton Synchrotron accelerator complex. The performance of the prototype is presented and compared to that of a Geant4 simulation of the apparatus. Particular emphasis is given to the response uniformity across the channel front face, and to the prototype׳s energy resolution.

A sampling calorimeter using cerium fluoride scintillating crystals as active material, interleaved with absorber plates made of tungsten, and read out by wavelength-shifting fibres has been tested with high-energy electron beams at the CERN SPS H4 beam line, as well as with lower-energy beams at the INFN Frascati Beam Test Facility in Italy. Energy resolution studies revealed a low stochastic term (<10%/E). This result, combined with high radiation hardness of the material used, marks this sampling calorimeter as a good candidate for the detectors׳ forward regions during the high luminosity phase of LHC.

The High-Luminosity phase of the Large Hadron Collider at CERN (HL-LHC) poses stringent requirements on calorimeter performance in terms of resolution, pileup resilience and radiation hardness. A tungsten-CeF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> sampling calorimeter is a possible option for the upgrade of current detectors. A prototype, read out with different types of wavelength-shifting fibers, has been built and exposed to high energy electrons, representative for the particle energy spectrum at HL-LHC, at the CERN SPS H4 beam line. This paper shows the performance of the prototype, mainly focussing on energy resolution and uniformity. A detailed simulation has been also developed in order to compare with data and to extrapolate to different configurations to be tested in future beam tests. Additional studies on the calorimeter and the R&D projects ongoing on the various components of the experimental setup will be also discussed.

The mechanism of production of heavy-flavoured jets, originated by the hadronization of b or c quarks, in association with vector bosons, W or Z, in the Standard Model is of primary importance. The study of events with one or two well-identified and isolated leptons accompanied by b-jets or displaced secondary vertices is therefore crucial to refine the theoretical calculations in perturbative QCD, as well as validate associated predictions from simulation. The understanding of these processes is furthermore required by Higgs and Beyond the Standard Model searches with similar final states. Using the LHC proton-proton collision data collected at a center of mass energy of 7 TeV by the CMS detector, measurements of the W+b, W+c, Z+b and Z+B hadrons cross sections are presented, comparing experimental data with several theoretical predictions in quantum chromodynamics.

The mechanism of production of heavy-flavoured mesons, containing b or c quarks, in association with vector bosons, W or Z, in the Standard Model is only partially understood. The study of events with one or two well-identified and isolated leptons accompanied by b-jets or secondary vertices is therefore crucial to refine the theoretical calculations in perturbative QCD, as well as validate associated Monte Carlo techniques. The deep understanding of these processes is furthermore required by Higgs and BSM analyses with similar final states. Using the LHC proton-proton collision data collected at a centre of mass energy of 7 and 8 TeV by the CMS detector, preliminary measurements of the Z/W+b(b) cross sections and angular correlations are presented. Finally, the study of the W+c production rate with respect to the W charge and W+light jets rates allows to probe the strange quark content of the proton. These results are also presented. Presented at BEACH 2014 XI International Conference on Hyperons, Charm and Beauty Hadrons Associated production of heavy flavors and W, Z bosons at CMS

The production of a vector boson (V = W, Z) in association with jets is can be used for a precise test of perturbative QCD and is a dominant background process in many searches for physics beyond the Standard Model. The differential cross section measurements from CMS and ATLAS collaborations would be presented, and several theoretical predictions at leading order (LO) and next-to leading order (NLO) are compared to data, after the deconvolution of detector effects, with proton-proton collisions at a center of mass energy of 7, 8 and 13 TeV at LHC.

In 2012, 14 Italian institutions participating in LHC Experiments won a grant from the Italian Ministry of Research (MIUR), with the aim of optimising analysis activities, and in general the Tier2/Tier3 infrastructure. We report on the activities being researched upon, on the considerable improvement in the ease of access to resources by physicists, also those with no specific computing interests. We focused on items like distributed storage federations, access to batch-like facilities, provisioning of user interfaces on demand and cloud systems. R&D on next-generation databases, distributed analysis interfaces, and new computing architectures was also carried on. The project, ending in the first months of 2016, will produce a white paper with recommendations on best practices for data-analysis support by computing centers.

The muon collider is one of the most attractive projects for the next generation colliders, capable of providing leptonic collisions at the energies of several TeV.The first study about the muon collider prospects for the measurement of the Higgs boson production cross section times the branching ratio for the Higgs boson decay to a pair of muons ( → ) is presented.The analysis is performed considering a 3-TeV muon collider and assuming an integrated luminosity of 1 ab -1 .This study is performed with a full simulation of the muon collider detector.It is shown that the expected number of signal events in the di-muon system invariant mass range from 105 to 145 GeV is 25.8 ± 9.9.The sensitivity on the measurement of × ( → ) is estimated to be 38%.

The Large Hadron Collider at CERN is the world's most efficient jet factory.In this report the properties of jets will be discussed, with focus on reconstructed jets in the ATLAS, CMS and LHCb experiments.After a brief introduction of jet physics at colliders, a selection of the results on inclusive QCD jet production cross sections, jets originated from the hadronization of b quarks and top quarks final states will be shown, with special attention on the comparisons with the Monte Carlo generators predictions at the highest possible order in perturbative QCD, using proton-proton collisions data at the center of mass energy p s = 7, 8 and 13 TeV.Details on the measurements of the running of the strong coupling constant as well as the differential cross sections for the inclusive jet production in ATLAS and CMS are presented.An overview of the state-of-art algorithms for the b-quark tagging, following the measurement of the b-jets production in association with a Z boson in CMS and the decay of a Z boson to bottom quarks in LHCb are shown.The top quark pair production physics is then introduced, and the cross section measurement in forward region with LHCb is shown.Finally, predictions of the color flow between quarks are tested using angular considerations in top events in ATLAS.