Ruchi Chudasama

Deep learning techniques have been proven to provide excellent performance for a variety of high-energy physics applications, such as particle identification, event reconstruction and trigger operations. Recently, we developed an end-to-end deep learning approach to identify various particles using low-level detector information from high-energy collisions. These models will be incorporated in the CMS software framework (CMSSW) to enable their use for particle reconstruction or for trigger operation in real time. Incorporating these computational tools in the experimental framework presents new challenges. This paper reports an implementation of the end-to-end deep learning inference with the CMS software framework. The inference has been implemented on GPU for faster computation using ONNX. We have benchmarked the ONNX inference with GPU and CPU using NERSC’s Perlmutter cluster by building a Docker image of the CMS software framework.

The Pixel Luminosity Telescope is a silicon pixel detector dedicated to luminosity measurement at the CMS experiment at the LHC. It is located approximately 1.75 m from the interaction point and arranged into 16 "telescopes", with eight telescopes installed around the beam pipe at either end of the detector and each telescope composed of three individual silicon sensor planes. The per-bunch instantaneous luminosity is measured by counting events where all three planes in the telescope register a hit, using a special readout at the full LHC bunch-crossing rate of 40 MHz. The full pixel information is read out at a lower rate and can be used to determine calibrations, corrections, and systematic uncertainties for the online and offline measurements. This paper details the commissioning, operational history, and performance of the detector during Run 2 (2015-18) of the LHC, as well as preparations for Run 3, which will begin in 2022.

During 2013 and 2014 (Long Shutdown LS1) the CMS experiment is upgrading the forward region installing a fourth layer of RPC detectors in order to complete and improve the muon system performances in the view of the foreseen high luminosity run of LHC. The new two endcap disks consists of 144 double-gap RPC chambers assembled at three different production sites: CERN, Ghent (Belgium) and BARC (India). The chamber components as well as the final detectors are subjected to full series of tests established in parallel at all the production sites.

The Resistive Plate Chambers (RPCs) are employed in the CMS Experiment at the LHC as dedicated trigger system both in the barrel and in the endcap. This article presents results of the radiation background measurements performed with the 2011 and 2012 proton-proton collision data collected by CMS. Emphasis is given to the measurements of the background distribution inside the RPCs. The expected background rates during the future running of the LHC are estimated both from extrapolated measurements and from simulation.

The muon spectrometer of the CMS (Compact Muon Solenoid) experiment at the Large Hadron Collider (LHC) is equipped with a redundant system made of Resistive Plate Chambers and Drift Tube in barrel and RPC and Cathode Strip Chamber in endcap region. In this paper, the operations and performance of the RPC system during the first three years of LHC activity will be reported. The stability of RPC performance, such as efficiency, cluster size and noise, will be reported. Finally, the radiation background levels on the RPC system have been measured as a function of the LHC luminosity. Extrapolations to the LHC and High Luminosity LHC conditions are also discussed.

Due to their flexibility, FPGAs are used to deploy Deep Neural Network Accelerators (DA) at various compute locations such as servers and edge computes. In this work, we show the impact of choosing architectural parameters on performance metrics for SOTA DA implemented on FPGA, and the optimal design point for maximum compute throughput.

Deep learning techniques have been proven to provide excellent performance for a variety of high-energy physics applications, such as particle identification, event reconstruction and trigger operations. Recently, we developed an end-to-end deep learning approach to identify various particles using low-level detector information from high-energy collisions. These models will be incorporated in the CMS software framework (CMSSW) to enable their use for particle reconstruction or for trigger operation in real-time. Incorporating these computational tools in the experimental framework presents new challenges. This paper reports an implementation of the end-to-end deep learning inference with the CMS software framework. The inference has been implemented on GPU for faster computation using ONNX. We have benchmarked the ONNX inference with GPU and CPU using NERSCs Perlmutter cluster by building a docker image of the CMS software framework.

A new muon reconstruction algorithm is introduced at the CMS experiment. This algorithm reconstructs muons using only the central tracker and the Resistive Plate Chamber (RPC). The aim of this work is to study how a muon reconstructed only with tracker and RPC information would perform compared to the standard muon reconstruction of the CMS detector. The efficiencies to reconstruct and identify a RPC muon with a transverse momentum greater than 20 GeV/c are measured. The probabilities to misidentify hadrons as muons at low transverse momentum are also reported. These probabilities are compared to the standard muon identification used at CMS.

This document collects the proceedings of the PHOTON 2017 conference ("International Conference on the Structure and the Interactions of the Photon", including the 22th "International Workshop on Photon-Photon Collisions", and the "International Workshop on High Energy Photon Colliders") held at CERN (Geneva) in May 2017. The latest experimental and theoretical developments on the topics of the PHOTON conference series are covered: (i) $γ\,γ$ processes in e$^+$e$^-$, proton-proton (pp) and nucleus-nucleus (AA) collisions at current and future colliders, (ii) $γ$-hadron interactions in e$^\pm$p, pp, and AA collisions, (iii) final-state photon production (including Standard Model studies and searches beyond it) in pp and AA collisions, and (iv) high-energy $γ$-ray astrophysics. These proceedings are dedicated to the memory of Maria Krawczyk.

Evidence for the light-by-light scattering process, γγ → γγ, in ultraperipheral PbPb collisions at a centre-of-mass energy per nucleon pair of 5.02 TeV is reported.The analysis is conducted using a data sample corresponding to an integrated luminosity of 390 µb -1 recorded by the CMS experiment at the LHC.Light-by-light scattering processes are selected in events with two photons exclusively produced, each with transverse energy E T > 2 GeV, pseudorapidity abs(η) < 2.4, diphoton invariant mass m γγ > 5 GeV, diphoton transverse momentum p γγ T < 1 GeV, and diphoton acoplanarity below 0.01.After all selection criteria are applied, 14 events are observed, compared to expectations of 11.1±1.1 (theo) events for the signal and 4.0±1.2(stat) for the background processes.The excess observed in data relative to the background-only expectation corresponds to a significance of 4.1 standard deviations, and has properties consistent with those expected for the light-by-light scattering signal.The m γγ distribution is used to set new exclusion limits on the production of pseudoscalar axion-like particles, via the γγ → a → γγ process, in the mass range m a = 5-90 GeV.

The Resistive Plate Chambers (RPC) are used in the CMS experiment at the trigger level and also in the standard offline muon reconstruction. In order to guarantee the quality of the data collected and to monitor online the detector performance, a set of tools has been developed in CMS which is heavily used in the RPC system. The Web-based monitoring (WBM) is a set of java servlets that allows users to check the performance of the hardware during data taking, providing distributions and history plots of all the parameters. The functionalities of the RPC WBM monitoring tools are presented along with studies of the detector performance as a function of growing luminosity and environmental conditions that are tracked over time.

February 1 th 2013 marked the end of the first period of running of the Large Hadron Collider (LHC) and the start of a two-year break from operation (LS1) aimed at consolidating both the accelerator as well as the detectors. By the end of LS1, the LHC is expected to provide collisions at 13 Tev. While, by 2020, the ultimate instantaneous luminosity is expected to be 1034/cm2/s. To prepare for this scenario, the Resistive Plate Chamber system at the CMS experiment is planning several detector maintainance and consolidation interventions. These include High Voltage and Low Voltage system reparations, gas leak identification and reparation, signal channel connectivity and functionality. Commissioning and upgrade plans for the existing CMS RPC system are presented here.

Exclusive W+ Wpair production in photon-photon collisions during the pp runs at 7 and 8TeV are observed and used to put constraints on the Anomalous Quartic Gauge Couplings. During the proton lead collisions in photon-induced vector meson production is observed via the decay of Ypsilon into two muons. The slope of the squared pT distribution is measured to determine the size of the production region. Presented at DIS 2016 XXIV International Workshop on Deep-Inelastic Scattering and Related Subjects Exclusive production observed at the CMS experiment Ruchi Chudasama (for the CMS Collaboration)∗ Nuclear Physics Division Bhabha Atomic Research Center Mumbai, India E-mail: ruchi.physics@gmail.com Exclusive W+W− pair production in photon-photon collisions during the pp runs at 7 and 8 TeV are observed and used to put constraints on the Anomalous Quartic Gauge Couplings. During the proton lead collisions in photon-induced vector meson production is observed via the decay of upsilon into two muons. The slope of the squared pT distribution is measured to determine the size of the production region. XXIV International Workshop on Deep-Inelastic Scattering and Related Subjects 11-15 April, 2016 DESY Hamburg, Germany

Results of exclusive photoproduction of Upsilon states in Ultraperipheral collisions (UPC) of protons and ions with the CMS experiment are presented, which provides a clean probe of the gluon distribution at small values of parton fractional momenta $x \approx 10^{-2} 10^{4}$ at central rapidities (|y| $< 2.5$). The three Upsilon states (1S, 2S, 3S) are measured in the dimuon decay channel along with the photon-photon decaying to dimuon QED continuum at $\sqrt{s_{NN}}=5.02$~TeV for integrated luminosity of $L_{int} = 35$ nb$^{-1}$. The total Upsilon photoproduction cross sections at different photon-proton center of mass energy $W_{\gamma p}$ and t-differential distributions are presented and compared with other experimental results as well as theoretical predictions.

The Compact Muon Solenoid is a general purpose detector being operated at Large Hadron Collider facility at CERN. The RE4 (fourth layer of RPC end-cap) upgrade project was envisaged to improve the muon trigger efficiency in the pseudo-rapidity range of 1.2–1.6 for LHC run at energy of 13 TeV and luminosity of $$10^{34}$$ cm $$^{2}$$ s $$^{-1}$$ . A total of 200 Resistive Plate Chambers were built for the upgrade at three assembly sites in Belgium, CERN and India. The assembly and characterization of 50 chambers was carried out jointly by Bhabha Atomic Research Center and Panjab University in India. The gas-gaps from South Korea underwent mechanical tests for leak and popped spacers, followed by electrical tests for leakage currents. Each assembled chamber was characterized by evaluation of efficiency, cluster size, noise and strip profile and are successfuly installed at Compact Muon Solenoid detector.

Recent results of exclusive photoproduction of heavy vector mesons at LHC energies by CMS, ALICE and LHCb [1] in ultraperipheral collisions (UPC) confirmed the expectations that UPCs are a very promising probe to study the gluon distributions in nucleons and in nuclei at small x [2, 3]. In this work, we estimate the photoproduction of Υ in the framework of perturbative two-gluon exchange formalism employing various parametrization of gluon distribution functions and compare with the experimental results of HERA [4] and LHCb. The study predicts the rapidity distributions of exclusive Υ photoproduction in PbPb UPC collisions at √ sNN = 5.12 TeV, the future heavy ion collision scenario at LHC in Run2.

Exclusive W$^{+}$W$^{-}$ pair production in photon-photon collisions during the pp runs at 7 and 8 TeV are observed and used to put constraints on the Anomalous Quartic Gauge Couplings. During the proton lead collisions in photon-induced vector meson production is observed via the decay of upsilon into two muons. The slope of the squared p$_{\rm T}$ distribution is measured to determine the size of the production region.

The RPC muon detector of the CMS experiment at the LHC (CERN, Geneva, Switzerland) is equipped with a Gas Gain Monitoring (GGM) system. A report on the stability of the system during the 2011-2012 data taking run is given, as well as the observation of an effect which suggests a novel method for the monitoring of gas mixture composition.

Exclusive W$^{+}$W$^{-}$ pair production in photon-photon collisions during the pp runs at 7 and 8 TeV are observed and used to put constraints on the Anomalous Quartic Gauge Couplings. During the proton lead collisions in photon-induced vector meson production is observed via the decay of upsilon into two muons. The slope of the squared p$_{\rm T}$ distribution is measured to determine the size of the production region.

Results of exclusive photoproduction of Upsilon states in Ultraperipheral collisions (UPC) of protons and ions with the CMS experiment are presented, which provides a clean probe of the gluon distribution at small values of parton fractional momenta $x \approx 10^{-2} 10^{4}$ at central rapidities (|y| $< 2.5$). The three Upsilon states (1S, 2S, 3S) are measured in the dimuon decay channel along with the photon-photon decaying to dimuon QED continuum at $\sqrt{s_{NN}}=5.02$~TeV for integrated luminosity of $L_{int} = 35$ nb$^{-1}$. The total Upsilon photoproduction cross sections at different photon-proton center of mass energy $W_{\gamma p}$ and t-differential distributions are presented and compared with other experimental results as well as theoretical predictions.

The CMS measurements of exclusive photoproduction of Υ in pPb and J/ψ in PbPb collisions, that probe the low-x gluon density in the proton and the lead nucleus respectively, are discussed.

The exclusive $\Upsilon$ photoproduction in ultraperipheral proton-nucleus and nucleus-nucleus collisions at LHC energies is being investigated using pQCD framework which constrain the gluon distribution in the proton and nuclei at low $x$. Rapidity distributions of $\Upsilon$ photoproduction with different gluon distribution parameterization and gluon shadowing for nuclear PDFs including photon flux suppression for strong interaction, are being presented at LHC energies. Predictions done for ultraperipheral collisions at $\sqrt s$=$8.16$ TeV in pPb, and at $\sqrt s$=$5.02$ TeV in PbPb collisions which are LHC Run 2 Heavy Ion collision scenario and measurements of cross-section will be available soon.

We discuss the measurement of photon-photon processes using data collected by the CMS experiment in pp collisions at sqrt(s) = 7 and sqrt(8) TeV and in PbPb collisions at sqrt(s_NN) =5.02 TeV.

Relativistic heavy ions are a copious source of virtual photons, which allow to study the gammaproton interactions in ultraperipheral collisions (UPC).The exclusive photoproduction of heavy vector mesons provide a clean probe of the gluon distribution at very small values of parton fractional momenta x ≈ 10 -2 -10 -4 at central rapidities (|y| < 2.2) and search for saturation phenomena.The first measurement of exclusive photoproduction of ϒ (1S, 2S, 3S) states in their dimuon decay channel in ultraperipheral collisions of protons and heavy ions (pPb) with the CMS experiment at √ s NN = 5.02 TeV for an integrated luminosity L int = 33 nb -1 was presented.The photoproduction cross section of ϒ (1S) was measured as a function of photon-proton center-ofmass energy W γ p .The differential cross section dσ /dt, where t is the squared four-momentum transfer at the photon-proton vertex, was measured in the range |t| < 1.0 (GeV/c) 2 .The results were compared with other measurements and theoretical predictions.

The exclusive $\Upsilon$ photoproduction in ultraperipheral proton-nucleus and nucleus-nucleus collisions at LHC energies is being investigated using pQCD framework which constrain the gluon distribution in the proton and nuclei at low $x$. Rapidity distributions of $\Upsilon$ photoproduction with different gluon distribution parameterization and gluon shadowing for nuclear PDFs including photon flux suppression for strong interaction, are being presented at LHC energies. Predictions done for ultraperipheral collisions at $\sqrt s$=$8.16$ TeV in pPb, and at $\sqrt s$=$5.02$ TeV in PbPb collisions which are LHC Run 2 Heavy Ion collision scenario and measurements of cross-section will be available soon.

Light-by-light (LbL) scattering ( $$\gamma \gamma \rightarrow \gamma \gamma $$ ) is a fundamental quantum mechanical process which could not be observed until recently due to its tiny cross section. By using huge photon fluxes from lead-on-lead (PbPb) ultraperipheral collisions (UPCs), the process has now been observed by both ATLAS and CMS experiments. LbL process is also a sensitive channel to probe physics beyond the standard model where an intermediate pseudoscalar, axion-like-particle (a) could be produced, i.e., ( $$\gamma \gamma \rightarrow a \rightarrow \gamma \gamma $$ ). The diphoton invariant mass distribution of LbL process is used to search for such a resonance production. A new exclusion limits on the mass of the pseudoscalar axion-like particles, in the range of 5–90 GeV has been set. This report will discuss highlights of the measurement of LbL scattering by CMS experiment.

Exclusive photoproduction of vector mesonsVector mesons (Upsilon and Rho $$^{0}$$ ) is studied with the large photon flux available in ultra-peripheral pPb collisions at $$\sqrt{s_{\mathrm{NN}}} $$ =5.02 TeV with the CMS experiment. It provides a clean probe of the gluon distribution at small values of parton fractional momenta x at central rapidities ( $$|y| < 2.5$$ ). The cross sectionsCross section are measured as a function of the photon-proton centre-of-mass energy, extending the energy range explored by H1 and ZEUS experiments at HERA. In addition, the differential cross sectionsCross section ( $$d\sigma /dt$$ ), where |t| $$\approx p_\mathrm{T}^2$$ , the squared transverse momentum of produced vector mesonsVector mesons, are measured and the slope parameters are obtained. The results are compared to previous measurements and to theoretical predictions. Finally, prospects for further measurements of vector meson production that can be performed using pPb collision data at 8 TeV collected at the end of 2016 are presented.

With excellent performance the Compact Muon Solenoid (CMS) experiment has made a number of key observations in the diffractive and exclusive processes and hence in probing the Standard model in a unique way. This presentation will cover recent results on the measurement of diffractive and exclusive processes using data recorded by CMS detector at the LHC.

With excellent performance the Compact Muon Solenoid (CMS) experiment has made a number of key observations in the diffractive and exclusive processes and hence in probing the Standard model in a unique way. This presentation will cover recent results on the measurement of diffractive and exclusive processes using data recorded by CMS detector at the LHC.

With excellent performance the Compact Muon Solenoid (CMS) experiment has made a number of key observations in the diffractive and exclusive processes and hence in probing the Standard model in a unique way. This presentation will cover recent results on the measurement of diffractive and exclusive processes using data recorded by CMS detector at the LHC.