Abideh Jafari

The upgrade of the LHC to the High-Luminosity LHC (HL-LHC) is expected to increase the LHC design luminosity by an order of magnitude. This will require silicon tracking detectors with a significantly higher radiation hardness. The CMS Tracker Collaboration has conducted an irradiation and measurement campaign to identify suitable silicon sensor materials and strip designs for the future outer tracker at the CMS experiment. Based on these results, the collaboration has chosen to use n-in-p type silicon sensors and focus further investigations on the optimization of that sensor type. This paper describes the main measurement results and conclusions that motivated this decision.

In order to stimulate new engagement and trigger some concrete studies in areas where further work would be beneficial towards fully understanding the physics potential of an $e^+e^-$ Higgs / Top / Electroweak factory, we propose to define a set of focus topics. The general reasoning and the proposed topics are described in this document.

A bstract A search for new top quark interactions is performed within the framework of an effective field theory using the associated production of either one or two top quarks with a Z boson in multilepton final states. The data sample corresponds to an integrated luminosity of 138 fb − 1 of proton-proton collisions at $$ \sqrt{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math> = 13 TeV collected by the CMS experiment at the LHC. Five dimension-six operators modifying the electroweak interactions of the top quark are considered. Novel machine-learning techniques are used to enhance the sensitivity to effects arising from these operators. Distributions used for the signal extraction are parameterized in terms of Wilson coefficients describing the interaction strengths of the operators. All five Wilson coefficients are simultaneously fit to data and 95% confidence level intervals are computed. All results are consistent with the SM expectations.

The first study of W boson production in pPb collisions is presented, for bosons decaying to a muon or electron, and a neutrino. The measurements are based on a data sample corresponding to an integrated luminosity of 34.6 inverse nanobarns at a nucleon-nucleon centre-of-mass energy of sqrt(s[NN]) = 5.02 TeV, collected by the CMS experiment. The W boson differential cross sections, lepton charge asymmetry, and forward-backward asymmetries are measured for leptons of transverse momentum exceeding 25 GeV, and as a function of the lepton pseudorapidity in the abs(eta[lab]) < 2.4 range. Deviations from the expectations based on currently available parton distribution functions are observed, showing the need for including W boson data in nuclear parton distribution global fits.

The high luminosity upgrade of the Large Hadron Collider, foreseen for 2026, necessitates the replacement of the CMS experiment’s silicon tracker. The innermost layer of the new pixel detector will be exposed to severe radiation, corresponding to a 1 MeV neutron equivalent fluence of up to $$\Phi _{eq} = 2 \times 10^{16}$$ cm $$^{-2}$$ , and an ionising dose of $${\approx } 5$$ MGy after an integrated luminosity of 3000 fb $$^{-1}$$ . Thin, planar silicon sensors are good candidates for this application, since the degradation of the signal produced by traversing particles is less severe than for thicker devices. In this paper, the results obtained from the characterisation of 100 and 200 $$\upmu $$ m thick p-bulk pad diodes and strip sensors irradiated up to fluences of $$\Phi _{eq} = 1.3 \times 10^{16}$$ cm $$^{-2}$$ are shown.

In this research gas sealed Multi-Wire Proportional Counter (MWPC) including blades between anode wires and beta particles of 90Sr with 196 keV mean energy were considered. Ten different gases such as Noble gases mixtures with methane and several other pure gases were studied. In this type of detector, by using Garfield and Maxwell codes and for each of the gases, variation of different parameters such as first Townsend, electron attachment coefficients with variable electric field and their effects on pulse height or collected charge and in turn on Signal to Noise Ratio (SNR) were studied. Also the effect of anode voltage and its diameter and the pressure of gas on the pulse height were studied. Results show that Garfield and Maxwell codes can be used to study and improve the design of other gaseous detectors.

The top quark pair production at the LHC has been studied in details by ATLAS and CMS collaborations. In addition to the inclusive tt cross section, now measured with an unprecedented precision, the LHC Run I data are exploited to provide comprehensive modeling comparisons through differential measurements at particle and/or parton levels. Furthermore, the uncertainties related to extrapolations to the full phase space are constrained using the measurements within a fiducial volume of the detector. The tt events are investigated in boosted regimes using the jet substructure techniques. The production cross section of tt in addition to one or two b quarks is also measured. Finally, the LHC experiments have presented the very first tt measurements at √ s = 13 TeV, performed using up to 80 pb−1 of the LHC Run II data. Presented at LHCP2015 The 3rd Conference on Large Hadron Collider Physics The Top Quark Production at the LHC Abideh Jafari for the ATLAS and CMS collaborations1,a) 1Universite Catholique de Louvain, Louvain-la-Neuve, Belgium a)Abideh.Jafari@cern.ch Abstract. The top quark pair production at the LHC has been studied in details by ATLAS and CMS collaborations. In addition to the inclusive tt cross section, now measured with an unprecedented precision, the LHC Run I data are exploited to provide comprehensive modeling comparisons through differential measurements at particle and/or parton levels. Furthermore, the uncertainties related to extrapolations to the full phase space are constrained using the measurements within a fiducial volume of the detector. The tt events are investigated in boosted regimes using the jet substructure techniques. The production cross section of tt in addition to one or two b quarks is also measured. Finally, the LHC experiments have presented the very first tt measurements at √ s = 13 TeV, performed using up to 80 pb−1 of the LHC Run II data. The top quark pair production at the LHC has been studied in details by ATLAS and CMS collaborations. In addition to the inclusive tt cross section, now measured with an unprecedented precision, the LHC Run I data are exploited to provide comprehensive modeling comparisons through differential measurements at particle and/or parton levels. Furthermore, the uncertainties related to extrapolations to the full phase space are constrained using the measurements within a fiducial volume of the detector. The tt events are investigated in boosted regimes using the jet substructure techniques. The production cross section of tt in addition to one or two b quarks is also measured. Finally, the LHC experiments have presented the very first tt measurements at √ s = 13 TeV, performed using up to 80 pb−1 of the LHC Run II data.

An overview of the CMS top quark cross section measurements withthe focus on the latest results is presented. Presented at LaThuile 2016 Les Rencontres de Physique de la Vallee dAoste IL NUOVO CIMENTO Vol. ?, N. ? ? Top Quark Production Measurements with CMS A. Jafari on behalf of the CMS Collaboration (∗) Universite Catholique de Louvain, Louvain-la-Neuve, Belgium Summary. — An overview of the CMS top quark cross section measurements with the focus on the latest results is presented. PACS 14.65.Ha – Top Quark. 1. – Introduction More than 20 years after its discovery, the top quark [1, 2] is still considered an effective testing ground to validate the standard model (SM) or to see hints for new physics connected to this heaviest known particle. At the CERN Large Hadron Collider (LHC) the top quark is predominantly produced through strong interactions in pair (tt) and to lesser extent in single mode via electroweak processes. The latter has three production mechanisms, t-channel, tW and s-channel, ordered by their rate at the LHC. The tt and single-top cross sections have been measured by the CMS experiment [3] with an unprecedented precision using the LHC Run I data [4, 5, 6]. The large data sample of top quarks recorded by the CMS experiment is also exploited to validate Monte-Carlo generators and theory calculations through inclusive and differential measurements of the top quark cross section and properties in the full phase space or within the detector acceptance. With the LHC start up in 2015, colliding protons at √ s = 13 TeV, top quark events were used as a commissioning tool thanks to the diversity of particles in their final state, i.e., t→ bW→ b`ν and/or t→ bW→ bqq′. The CMS experiment has performed inclusive and differential cross section measurements using the very first 13 TeV proton collisions and soon, updated the analyses with the entire 2015 data. The inclusive tt cross sections are already limited by systematic uncertainties. 2. – Run I legacy σtt measurement in the `+jets and eμ final states In the `+jets analysis [7] events with exactly one isolated high pT muon or electron, originating from the vertex of the interaction, are required to have at least four jets of (∗) email: abideh.jafari@cern.ch c © CERN on behalf the CMS Collaboration 1 2 A. JAFARI ON BEHALF OF THE CMS COLLABORATION which one is likely to be coming from a b quark. The hadronically decaying top quark is reconstructed using the three jet combination minimizing a χ value which is constrained by the mass of the top quark and the W boson. The energy of the jets assigned to the W boson are recalibrated using mW constraint. The M`b variable is defined as the invariant mass of the selected lepton and the remaining jet which is supposedly a b-quark jet. It is used to extract the top quark cross section as well as the b-quark jet identification efficiency. Figure 1 illustrates the M`b distributions for the electron and muon channel of the analysis. To extract σtt, binned maximum likelihood fits to these distributions are performed and the results are combined using the BLUE method. The combined cross section is measured in the fiducial volume and extrapolated to the full phase space, yielding σtt(8 TeV) = 228.5 ± 3.8 (stat.) ± 13.7 (syst.) ± 6.0(lumi.) pb, compatible with SM predictions, σtt = 252.89 +13.3 −14.5 pb. The dominant systematic uncertainties are from Jet Energy Scale (JES) and signal modeling. The σtt(7 TeV) is measured with a similar method leading to a cross section ratio of Rtt ≡ σtt(8 TeV) σtt(7 TeV) = 1.43 ± 0.09, in agreement with the SM calculations, 1.43±0.01. The analysis at 8 TeV (7 TeV) uses 19.7 (5.0) fb−1 of the LHC collision data. (GeV) b μ M 0 50 100 150 200 250 300 350 400 450 500 E ve nt s/ 10 G eV 0 500 CMS 100

The CMS and ATLAS experiments have performed detailed studies on the electroweakly produced top quarks at the LHC. These studies range from accurate measurements of the cross section and $|V_{\rm tb}|$ in different production modes to search for new interactions in the $\rm tWb$ vertex. Moreover, different properties of the top quark are precisely measured in this context. All measurements are consistent with the standard model and no sign of new physics is observed.

A selected set of CMS measurements of the top quark properies in $t$-channel single top events together with searches for anomalous top quark couplings are presented. In particular the first tZq cross section measurement is briefly described. All results are based on the analysis of the LHC data at $\sqrt{s}=8\,\rm TeV$ with an integrated luminosity of $19.7\text{fb}^{-1}$.

We present different measurements of the top quark properties in production and decay. The measurements are performed using the LHC proton-proton (pp) collisions at 7 TeV and 8 TeV center-of-mass energies collected by the CMS detector during 2011 and 2012 runs, respectively. The study of production properties consists of charge asymmetry, spin correlation and the vector boson associated production of . The top quark properties in decay are studied via the measurement of the b-quark content, R = ℬ(t → Wb)/ℬ(t → Wq), the top quark charge, the FCNC process of t → Zq and the W-helicity fractions. The results of the last measurement are used to set limits on the tWb anomalous couplings. The W-helicity fractions are measured in the electroweakly produced (single-) top quarks, too.

A selected set of CMS measurements of the top quark properies in t-channel single top events together with searches for anomalous top quark couplings are presented.In particular the first tZq cross section measurement is briefly described.All results are based on the analysis of the LHC data at √ s = 8 TeV with an integrated luminosity of 19.7fb -1 .

In the 10^th International Workshop on the CKM Unitarity Triangle, the sessions of the High-p T flavor physics were devoted to the related topics in top quark physics, Higgs physics, semileptonic decays of B mesons and leptoquark searches. This notes summarizes the highlights of discussions on top quark and Higgs physics.

In the 10^th International Workshop on the CKM Unitarity Triangle, the sessions of the High-p T flavor physics were devoted to the related topics in top quark physics, Higgs physics, semileptonic decays of B mesons and leptoquark searches. This notes summarizes the highlights of discussions on top quark and Higgs physics.