arXiv subjects

Andrei Nomerotski

Publications and source records attributed to Andrei Nomerotski.

63 records · Page 4Linked to original sources

arXiv2011

Top quark anomalous couplings at the International Linear Collider

We present a study of the experimental determination of the forward-backward asymmetry in the process $e^+e^-\to t\bar t$ and in the subsequent $t\to Wb$ decay, studied in the context of the International Linear Collider. This process probes the elementary couplings of the top quark to the photon, the $Z$ and the $W$ bosons at a level of precision that is difficult to achieve at hadron colliders. Measurement of the forward-backward asymmetry requires excellent $b$ quark identification and determination of the quark charge. The study reported here is performed in the most challenging all-hadronic channel $e^+e^- \to b\bar b q\bar q q\bar q$. It includes realistic details of the experimental environment, a full Monte Carlo simulation of the detector, based on the Silicon Detector concept, and realistic event reconstruction. The forward-backward asymmetries are determined to a precision of approximately 1% for each of two choices of beam polarization. We analyze the implications for the determination of the $t\bar t Z$ and $Wtb$ couplings.

hep-ex↗

arXiv2011

Discovering Bottom Squark Co-annihilation at ILC

We study the potential of International Linear Collider (ILC) at sqrt(s) = 500 GeV to probe new dark matter motivated scenario where the bottom squark (sbottom) is the next to lightest supersymmetric particle. For this scenario, which is virtually impossible for the LHC to test, the ILC has a potential to cover a large fraction of the parameter space. The challenge is due to a very low energy of jets, below 20-30 GeV, which pushes the jet clustering and flavour tagging algorithms to their limits. The process of sbottom pair production was studied within the SiD detector concept. We demonstrate that ILC offers a unique opportunity to test the SUSY parameter space motivated by the sbottom neutralino co-annihilation scenario in cases when the sbottom production is kinematically accessible. The study was done with the full SiD simulation and reconstruction chain including all Standard Model and beam backgrounds.

hep-ph↗

arXiv2010

ISIS2: Pixel Sensor with Local Charge Storage for ILC Vertex Detector

ISIS (In-situ Storage Imaging Sensor) is a novel CMOS sensor with multiple charge storage capability developed for the ILC vertex detector by the Linear Collider Flavour Identification (LCFI) collaboration. This paper reports test results for ISIS2, the second generation of ISIS sensors implemented in a 0.18 micron CMOS process. The local charge storage and charge transfer were unambiguously demonstrated.

physics.ins-det↗

arXiv2010

Higgs boson hadronic branching ratios at the ILC

We present a study of the Higgs boson decay branching ratios to $b\bar{b}$, $c\bar{c}$ and gluons, one of the cornerstones of the physics program at the International Linear Collider (ILC). A standard model Higgs boson of 120\,GeV mass, produced in the Higgs-strahlung process at $\sqrt{s} = 250$\,GeV was investigated using the full detector simulation and reconstruction procedures. The analysis was performed in the framework of the Silicon Detector (SiD) concept with full account of inclusive standard model backgrounds. The selected decay modes contained two heavy flavour jets in the final state and required excellent flavour tagging through precise reconstruction of interaction and decay vertices in the detector. A new signal discrimination technique using correlations of neural network outputs was used to determine the branching ratios and estimate their uncertainties, 4.8\%, 8.4\% and 12.2\% for $b\bar{b}$, $c\bar{c}$ and gluons respectively.

hep-ph↗

arXiv2010

Chargino and Neutralino Masses at ILC

The chargino/neutralino pair production is one of the benchmarking processes of ILC. These processes are interesting not only because it allows high precision measurement of chargino and neutralino masses, but also for the reason that the separation of W and Z bosons through their hadronic decay products requires excellent jet resolution being a good benchmark of the detector performance. The analysis based on the SiD detector concept with four jets and missing energy final state will be presented. The uncertainty of chargino and neutralino cross sections can be determined with precision of 0.9% and 4.2% respectively. The mass uncertainties are obtained with a template fitting method achieving precision of better than 1 GeV.

physics.ins-det↗

arXiv2009

Comparison of Measurements of Charge Transfer Inefficiencies in a CCD with High-Speed Column Parallel Readout

Charge Coupled Devices (CCDs) have been successfully used in several high energy physics experiments over the past two decades. Their high spatial resolution and thin sensitive layers make them an excellent tool for studying short-lived particles. The Linear Collider Flavour Identification (LCFI) Collaboration has been developing Column-Parallel CCDs for the vertex detector of a future Linear Collider which can be read out many times faster than standard CCDs. The most recent studies are of devices designed to reduce both the CCD's intergate capacitance and the clock voltages necessary to drive it. A comparative study of measured Charge Transfer Inefficiency values between our previous and new results for a range of operating temperatures is presented.

physics.ins-det↗

arXiv2009

The LCFIVertex package: vertexing, flavour tagging and vertex charge reconstruction with an ILC vertex detector

The precision measurements envisaged at the International Linear Collider (ILC) depend on excellent instrumentation and reconstruction software. The correct identification of heavy flavour jets, placing unprecedented requirements on the quality of the vertex detector, will be central for the ILC programme. This paper describes the LCFIVertex software, which provides tools for vertex finding and for identification of the flavour and charge of the leading hadron in heavy flavour jets. These tools are essential for the ongoing optimisation of the vertex detector design for linear colliders such as the ILC. The paper describes the algorithms implemented in the LCFIVertex package, as well as the scope of the code and its performance for a typical vertex detector design.

physics.ins-det↗

arXiv2008

Modeling of Charge Transfer Inefficiency in a CCD with High Speed Column Parallel Readout

Charge Coupled Devices (CCDs) have been successfully used in several high energy physics experiments over the past two decades. Their high spatial resolution and thin sensitive layers make them an excellent tool for studying short-lived particles. The Linear Collider Flavour Identification (LCFI) collaboration is developing Column-Parallel CCDs (CPCCDs) for the vertex detector of a future Linear Collider. The CPCCDs can be read out many times faster than standard CCDs, significantly increasing their operating speed. An Analytic Model has been developed for the determination of the charge transfer inefficiency (CTI) of a CPCCD. The CTI values determined with the Analytic Model agree largely with those from a full TCAD simulation. The Analytic Model allows efficient study of the variation of the CTI on parameters like readout frequency, operating temperature and occupancy.

physics.ins-det↗

arXiv1999

Stop and Sbottom Searches in Run II of the Fermilab Tevatron

We estimate the Tevatron Run II potential for top and bottom squark searches. We find an impressive reach in several of the possible discovery channels. We also study some new channels which may arise in non-conventional supersymmetry models. In each case we rely on a detailed Monte Carlo simulation of the collider events and the CDF detector performance in Run I.

hep-ph↗