Devdatta Majumder

The discovery of the Higgs boson in 2012, by the ATLAS and CMS experiments, was a success achieved with only a percent of the entire dataset foreseen for the LHC. It opened a landscape of possibilities in the study of Higgs boson properties, Electroweak Symmetry breaking and the Standard Model in general, as well as new avenues in probing new physics beyond the Standard Model. Six years after the discovery, with a conspicuously larger dataset collected during LHC Run 2 at a 13 TeV centre-of-mass energy, the theory and experimental particle physics communities have started a meticulous exploration of the potential for precision measurements of its properties. This includes studies of Higgs boson production and decays processes, the search for rare decays and production modes, high energy observables, and searches for an extended electroweak symmetry breaking sector. This report summarises the potential reach and opportunities in Higgs physics during the High Luminosity phase of the LHC, with an expected dataset of pp collisions at 14 TeV, corresponding to an integrated luminosity of 3 ab$^{-1}$. These studies are performed in light of the most recent analyses from LHC collaborations and the latest theoretical developments. The potential of an LHC upgrade, colliding protons at a centre-of-mass energy of 27 TeV and producing a dataset corresponding to an integrated luminosity of 15 ab$^{-1}$, is also discussed.

The CMS detector at the CERN LHC features a silicon pixel detector as its innermost subdetector. The original CMS pixel detector has been replaced with an upgraded pixel system (CMS Phase-1 pixel detector) in the extended year-end technical stop of the LHC in 2016/2017. The upgraded CMS pixel detector is designed to cope with the higher instantaneous luminosities that have been achieved by the LHC after the upgrades to the accelerator during the first long shutdown in 2013–2014. Compared to the original pixel detector, the upgraded detector has a better tracking performance and lower mass with four barrel layers and three endcap disks on each side to provide hit coverage up to an absolute value of pseudorapidity of 2.5. This paper describes the design and construction of the CMS Phase-1 pixel detector as well as its performance from commissioning to early operation in collision data-taking.

We propose simulation strategies for single production of third generation vector-like quarks at the LHC, implementing next-to-leading-order corrections in QCD and studying in detail their effect on cross sections and differential distributions. We also investigate the differences and the relative incertitudes induced by the use of the Four-Flavour Number Scheme ${\it versus}$ the Five-Flavour Number Scheme. As a phenomenological illustration, we concentrate on the production of vector-like quarks coupling to the third generation of the Standard Model in association with a jet and assuming standard couplings to gauge and Higgs bosons.

This report summarizes the activities of the SM and NLO Multileg Working Group of the Workshop "Physics at TeV Colliders", Les Houches, France 8-26 June, 2009.

We investigate Higgs-boson pair production at the LHC when the final state system arises from decays of vector-like quarks coupling to the Higgs boson and the Standard Model quarks. Our phenomenological study includes next-to-leading-order QCD corrections, which are important to guarantee accurate predictions, and focuses on a detailed analysis of a di-Higgs signal in the four $b$-jet channel. Whereas existing Run II CMS and ATLAS analyses are not specifically designed for probing non-resonant, vector-like-quark induced, di-Higgs production, we show that they nevertheless offer some potential for these modes. We then investigate the possibility of distinguishing between the various di-Higgs production mechanisms by exploiting the kinematic properties of the signal.

Abstract The CMS Inner Tracker, made of silicon pixel modules, will be entirely replaced prior to the start of the High Luminosity LHC period. One of the crucial components of the new Inner Tracker system is the readout chip, being developed by the RD53 Collaboration, and in particular its analogue front-end, which receives the signal from the sensor and digitizes it. Three different analogue front-ends (Synchronous, Linear, and Differential) were designed and implemented in the RD53A demonstrator chip. A dedicated evaluation program was carried out to select the most suitable design to build a radiation tolerant pixel detector able to sustain high particle rates with high efficiency and a small fraction of spurious pixel hits. The test results showed that all three analogue front-ends presented strong points, but also limitations. The Differential front-end demonstrated very low noise, but the threshold tuning became problematic after irradiation. Moreover, a saturation in the preamplifier feedback loop affected the return of the signal to baseline and thus increased the dead time. The Synchronous front-end showed very good timing performance, but also higher noise. For the Linear front-end all of the parameters were within specification, although this design had the largest time walk. This limitation was addressed and mitigated in an improved design. The analysis of the advantages and disadvantages of the three front-ends in the context of the CMS Inner Tracker operation requirements led to the selection of the improved design Linear front-end for integration in the final CMS readout chip.

Nanocomposites are often found in nature, as a multiphase solid material where one of the phases has one, two or three dimensions of less than 100 nm, or structures having nano-scale repeat distances between the different phases that make up the material. In this chapter the magnetic properties of ceramic nanocomposites are presented, along with structures which differ markedly from that of the component materials. It is emphasized that, in the case of nanocomposites, where the main part of the volume is occupied by ceramics (i.e. a chemical compound from the group of oxides, nitrides, borides or silicates, among others), further systematic study will be necessary to improve their optical, electrical and magnetic properties, as well as their tri-biological, corrosion resistance and other protective properties.

This is the summary and introduction to the proceedings contributions for the Les Houches 2009 "Tools and Monte Carlo" working group.

The PMTs of the CMS Hadron Forward calorimeter were found to generate a large size signal when their windows were traversed by energetic charged particles. This signal, which is due to Čerenkov light production at the PMT window, could interfere with the calorimeter signal and mislead the measurements. In order to find a viable solution to this problem, the response of four different types of PMTs to muons traversing their windows at different orientations is measured at the H2 beam-line at CERN. Certain kinds of PMTs with thinner windows show significantly lower response to direct muon incidence. For the four anode PMT, a simple and powerful algorithm to identify such events and recover the PMT signal using the signals of the quadrants without window hits is also presented. For the measurement of PMT responses to Čerenkov light, the Hadron Forward calorimeter signal was mimicked by two different setups in electron beams and the PMT performances were compared with each other. Superior performance of particular PMTs was observed.

We present the activities of the 'New Physics' working group for the 'Physics at TeV Colliders' workshop (Les Houches, France, 1-19 June, 2015). Our report includes new physics studies connected with the Higgs boson and its properties, direct search strategies, reinterpretation of the LHC results in the building of viable models and new computational tool developments. Important signatures for searches for natural new physics at the LHC and new assessments of the interplay between direct dark matter searches and the LHC are also considered.

Abstract During the operation of the CMS experiment at the High-Luminosity LHC the silicon sensors of the Phase-2 Outer Tracker will be exposed to radiation levels that could potentially deteriorate their performance. Previous studies had determined that planar float zone silicon with n-doped strips on a p-doped substrate was preferred over p-doped strips on an n-doped substrate. The last step in evaluating the optimal design for the mass production of about 200 m 2 of silicon sensors was to compare sensors of baseline thickness (about 300 μm) to thinned sensors (about 240 μm), which promised several benefits at high radiation levels because of the higher electric fields at the same bias voltage. This study provides a direct comparison of these two thicknesses in terms of sensor characteristics as well as charge collection and hit efficiency for fluences up to 1.5 × 10 15 n eq /cm 2 . The measurement results demonstrate that sensors with about 300 μm thickness will ensure excellent tracking performance even at the highest considered fluence levels expected for the Phase-2 Outer Tracker.

This work demonstrates the efficacy of engineered Aluminium doped Zinc Oxide to support an enhanced mid-IR plasmonic resonance which can be directly visualized from a significant 23% drop in mid-IR transmission measurements.

Abstract The long-term sustainability of the high-energy physics (HEP) research software ecosystem is essential to the field. With new facilities and upgrades coming online throughout the 2020s, this will only become increasingly important. Meeting the sustainability challenge requires a workforce with a combination of HEP domain knowledge and advanced software skills. The required software skills fall into three broad groups. The first is fundamental and generic software engineering (e.g., Unix, version control, C++, and continuous integration). The second is knowledge of domain-specific HEP packages and practices (e.g., the ROOT data format and analysis framework). The third is more advanced knowledge involving specialized techniques, including parallel programming, machine learning and data science tools, and techniques to maintain software projects at all scales. This paper discusses the collective software training program in HEP led by the HEP Software Foundation (HSF) and the Institute for Research and Innovation in Software in HEP (IRIS-HEP). The program equips participants with an array of software skills that serve as ingredients for the solution of HEP computing challenges. Beyond serving the community by ensuring that members are able to pursue research goals, the program serves individuals by providing intellectual capital and transferable skills important to careers in the realm of software and computing, inside or outside HEP.

Abstract The Short Strip ASIC (SSA) is one of the four front-end chips designed for the upgrade of the CMS Outer Tracker for the High Luminosity LHC. Together with the Macro-Pixel ASIC (MPA) it will instrument modules containing a strip and a macro-pixel sensor stacked on top of each other. The SSA provides both full readout of the strip hit information when triggered, and, together with the MPA, correlated clusters called stubs from the two sensors for use by the CMS Level-1 (L1) trigger system. Results from the first prototype module consisting of a sensor and two SSA chips are presented. The prototype module has been characterized at the Fermilab Test Beam Facility using a 120 GeV proton beam.

This is the summary and introduction to the proceedings contributions for the Les Houches 2009 Tools and Monte Carlo working group.

Butadiene–Rh and –Rh2 complexes have been studied using the density functional (DFT) and Møller–Plesset (MP2 and MP4) calculations. For the butadiene–Rh complex complete active space multiconfiguration self-consistent field method (CASMCSCF) followed by multireference singles and doubles (MRSDCI) calculations were employed. Two nearly degenerate structures were found as candidates for the ground state of the butadiene–Rh complex with a five-member planar ring structure and a trans non-planar structure. The ground state of the butadiene–Rh2 complex was found to be a 1A′ state in a half-boat equilibrium structure.

We present searches for massive top and bottom quark partners at CMS using LHC pp collision data collected at centre-of-mass energy $\sqrt{s} = 8$ TeV. Such partners can be found in models predicting vector-like quarks to solve the hierarchy problem and stabilize the Higgs boson mass. The searches span a range of final states containing several lepton and jet multiplicities, and limits were set on mass and production cross sections as a function of branching ratios.

The measurement of the inclusive cross section for Wgamma production is presented based on 36/ pb of data acquired with the CMS detector from 7 TeV LHC collisions in 2010. Comparisons are made with the predictions of the standard model. The W bosons are identified through their leptonic decays to electrons and muons. The Wgamma cross section is sensitive to anomalous triple-gauge couplings and hence this measurement probes physics beyond the standard model.

We present searches for massive top and bottom quark partners at CMS using LHC pp collision data collected at centre-of-mass energy $\sqrt{s} = 8$ TeV. Such partners can be found in models predicting vector-like quarks to solve the hierarchy problem and stabilize the Higgs boson mass. The searches span a range of final states containing several lepton and jet multiplicities, and limits were set on mass and production cross sections as a function of branching ratios.

We present searches for massive top and bottom quark partners at CMS using LHC pp collision data collected at centre-of-mass energy $\sqrt{s} = 8$ TeV. Such partners can be found in models predicting vector-like quarks to solve the hierarchy problem and stabilize the Higgs boson mass. The searches span a range of final states containing several lepton and jet multiplicities, and limits were set on mass and production cross sections as a function of branching ratios.

The study of dibosons like W γ, Zγ, WW , W Z and ZZ at the LHC will be an interesting test of the Electroweak gauge structure of the Standard Model at the highest possible energies , and may indicate the presence of new physics as deviations of the gauge boson couplings from their Standard Model values.We present here the analysis strategy for measuring the cross-sections for the WW and WZ processes and Monte Carlo generator-based studies of the physics of W γ and Zγ production at the LHC.We show that the WW cross-section can be measured with 100 pb -1 of data at √ s = 10 TeV and W Z, with 300 pb -1 of data at √ s = 14 TeV.

We compare a NLO W gamma matrix element generator with the leading order calculation in Pythia . A matching scheme between a next-to-leading order W gamma matrix element generator by Baur et. al. and the Pythia parton shower is presented. The NLO package produces W gamma+0 jet and W gamma+1jet final states in the hard scattering and the objective is to consistently match these to the initial state radiation from Pythia parton shower. The proposed methodology preserves both the rate of the hard scattering process as well as various kinematic distributions of experimental interest.

We present here a comparative study of PYTHIA monte carlo event generator and a matrix element calculation by Baur et. al. for W + production at proton-proton collision at the LHC. Baur’s calculation is at NLO containing all diagrams up to O( S) whereas PYTHIA contains diagrams only for the tree level process pp!W . We study how a NLO calculation makes a difference to the W + production mechanism at the LHC and what differences arise due to the use of parton shower modelling of the photon as well as the QCD radiation w.r.t. that from an exact matrix element calculation.

The highly lossy nature of the conventional noble metals in the infrared region limits their implementation to the UV-Vis part of the electromagnetic spectrum. Hence, the necessity for a lossless alternate plasmonic material having large negative permittivity in the IR regime has paved the way for the exploration of transparent conducting oxides such as Aluminium doped Zinc Oxide. The mid-IR plasmonic response has a strong dependence on diverse tuneable parameters, the most efficient and flexible being the geometrical parameters. Detailed theoretical investigations using COMSOL Multiphysics can obliterate the requirement of complex fabrication efforts to understand the dynamic tunability of the optical signal. This study is motivated by the systematic investigation of the effect of shape factors on the linear optical properties of three different AZO based plasmonic planar nanostructures namely Nonamer, Dipole, and BowTie nanoantennas. A comparative matrix for various configuration sensitive optical modes investigated by this work provides a unique possibility to encompass the idea for exploration and design of mid-IR photodetection and sensor-based devices.

Long term sustainability of the high energy physics (HEP) research software ecosystem is essential for the field. With upgrades and new facilities coming online throughout the 2020s this will only become increasingly relevant throughout this decade. Meeting this sustainability challenge requires a workforce with a combination of HEP domain knowledge and advanced software skills. The required software skills fall into three broad groups. The first is fundamental and generic software engineering (e.g. Unix, version control,C++, continuous integration). The second is knowledge of domain specific HEP packages and practices (e.g., the ROOT data format and analysis framework). The third is more advanced knowledge involving more specialized techniques. These include parallel programming, machine learning and data science tools, and techniques to preserve software projects at all scales. This paper dis-cusses the collective software training program in HEP and its activities led by the HEP Software Foundation (HSF) and the Institute for Research and Innovation in Software in HEP (IRIS-HEP). The program equips participants with an array of software skills that serve as ingredients from which solutions to the computing challenges of HEP can be formed. Beyond serving the community by ensuring that members are able to pursue research goals, this program serves individuals by providing intellectual capital and transferable skills that are becoming increasingly important to careers in the realm of software and computing, whether inside or outside HEP

The search for aCarvalho, Alexandra massive resonance produced by vector boson fusion and decaying into a pair of Higgs bosons,Komaragiri, Jyothsna Rani each decaying to a b quark-antiquark pair, at the High Luminosity Large Hadron Collider in proton-proton collisions at a centre-of-mass energy of 14 TeV is explored.Majumder, Devdatta The Higgs bosons are required to be sufficiently Lorentz-boosted for each to be reconstructed using a single large-area jet.Panwar, Lata We study the signal sensitivity for a narrow bulk graviton in extradimensional scenarios using a simulation of the upgraded CMS detector, assuming multiple proton-proton collisions in the same bunch crossing (up to 200), for data corresponding to an integrated luminosity of 3 ab $$^{-1}$$ . The expected significance for different assumed masses of the bulk graviton is presented.