M. Hashemi

M. Hashemi
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High Energy Physics - Phenomenology (22)
 
General Relativity and Quantum Cosmology (4)
 
Physics - Optics (4)
 
Mathematics - Information Theory (3)
 
Computer Science - Information Theory (3)
 
Statistics - Methodology (2)
 
Computer Science - Computer Vision and Pattern Recognition (2)
 
Physics - Materials Science (2)
 
High Energy Physics - Theory (2)
 
High Energy Physics - Experiment (2)
 
Nonlinear Sciences - Adaptation and Self-Organizing Systems (1)
 
Mathematics - Statistics (1)
 
Statistics - Theory (1)
 
Quantitative Biology - Neurons and Cognition (1)
 
Physics - Mesoscopic Systems and Quantum Hall Effect (1)
 
Computer Science - Architecture (1)
 
Computer Science - Software Engineering (1)
 
Computer Science - Distributed; Parallel; and Cluster Computing (1)
 
Computer Science - Networking and Internet Architecture (1)

Publications Authored By M. Hashemi

Epsilon-near-zero (ENZ) materials, including artificial metamaterials, have been advanced to mold laser beams and antenna-mediated radiated waves. Here we propose an efficient method to control Ohmic losses inherent to natural ENZ materials by the assembly of subwavelength structures in a nonperiodic matrix constituting an ENZ metacoating. Implemented over plano-concave transparent substrates whose radius can be of only a few wavelengths, ENZ surface-relief elements demonstrate to adequately shape a plane wave into highly localized fields. Read More

This paper addresses the question of observability of neutral Higgs bosons through the leptonic decay in a two Higgs doublet model (2HDM). Both scalar and pseudoscalar Higgs bosons ($H,~A$) are considered. The model is set to type IV to enhance the leptonic decay. Read More

In this work we investigate the observability of Inert Doublet Model scalars at the LHC operating at the center of mass energy of 14 TeV. The signal production process is $pp \to AH^\pm \to ZHW^{\pm}H$ leading to two different final states of $\ell^+\ell^-Hjj H$ and $\ell^+\ell^-H\ell^\pm\nu H$ based on the hadronic and leptonic decay channels of the W boson. All the relevant background processes are considered and an event selection is designed to distinguish the signal from the large Standard Model background. Read More

This dissertation develops hardware that automatically reduces the effective latency of accessing memory in both single-core and multi-core systems. To accomplish this, the dissertation shows that all last level cache misses can be separated into two categories: dependent cache misses and independent cache misses. Independent cache misses have all of the source data that is required to generate the address of the memory access available on-chip, while dependent cache misses depend on data that is located off-chip. Read More

We design plano-concave silicon lenses with coupled gradient-index plasmonic metacoatings for ultrawide apertured focusing utilizing a reduced region of $\sim 20 \lambda^2$. The anomalous refraction induced in the planar input side of the lens and in the boundary of the wavelength-scale focal region boosts the curvature of the emerging wavefront, thus significantly enhancing the resolution of the tightly-focused optical wave. The formation of a light tongue with dimensions approaching those of the concave opening is here evidenced. Read More

Based on the Padmanabhan's proposal, the accelerated expansion of the universe can be driven by the difference between the surface and bulk degrees of freedom in a region of space, described by the relation $ dV/dt = N_{sur}-N_{bulk}$ where $N_{sur}$ and $N_{bulk}$ are the degrees of freedom assigned to the surface area and the matter-energy content inside the bulk, respectively. In the present work, the dynamical effect of the Weyssenhoff perfect fluid with intrinsic spin and its corresponding spin degrees of freedom in the framework of Einstein-Cartan (EC) theory are investigated. Based on the modification of Friedmann equations due to the spin-spin interactions, a correction term for the Padmanabhan's relation including the number of degrees of freedom related to this spin interactions as $\Delta V /\Delta t=N_{sur}-N_{bulk}-N_{spin}$ is obtained where $N_{spin}$ is the corresponding degree of freedom related to the intrinsics spin of the matter content of the universe. Read More

With the current measurements performed by CMS and ATLAS experiments, the light charged Higgs scenario ($m_{H^{\pm}}$ $<$ 160 GeV), is excluded for most of the parameter space in the context of MSSM. However, there is still possibility to look for heavy charged Higgs boson particularly in the $s$-channel single top production process where the charged Higgs may appear as a heavy resonance state and decay to $t\bar{b}$. The production process under consideration in this paper is $pp \ra H^{\pm} \ra t\bar{b}~+~h. Read More

We investigate the phenomenology of the light charged and neutral scalars in Inert Doublet Model at future $e^+ e^-$ colliders with center of mass energies of 0.5 and 1 TeV, and integrated luminosity of 500~fb$^{-1}$. The analysis covers two production processes, $e^{+}e^{-} \rightarrow H^{+}H^{-}$ and $e^{+}e^{-}\rightarrow AH$, and consists of signal selections, cross section determinations as well as dark matter mass measurements. Read More

Many mobile applications running on smartphones and wearable devices would potentially benefit from the accuracy and scalability of deep CNN-based machine learning algorithms. However, performance and energy consumption limitations make the execution of such computationally intensive algorithms on mobile devices prohibitive. We present a GPU-accelerated library, dubbed CNNdroid, for execution of trained deep CNNs on Android-based mobile devices. Read More

In this paper, the question of observability of a heavy charged Higgs in the mass range 400 GeV < mH < 1000 GeV, is addressed. The production process is set to pp -> H+ -> tb at 14 TeV LHC. The analysis benefits from top tagging technique which is based on finding a fat jet as a result of the boosted top quark decay in signal events. Read More

The aim here is to provide a set of equations for cosmology in terms of information and thermodynamical parameters. The method we implement in order to describe the universe is a development of Padmanabhan\rq{}s approach which is based on the fact that emergence of the cosmic space is provided by the evolution of the cosmic time. In this line we obtain the Friedmann equation or its equivalent the conservation law in terms of information by the implementation of Laundauer\rq{}s principle or in other words the information loss/production rate. Read More

In this study the charged Higgs signal through triple or double Higgs production in a general two Higgs doublet model (2HDM) is investigated. The main production process is $e^+e^- \rightarrow H^+H^-H^0$ followed by the charged Higgs decay to a pair of $\tau \nu$ and the neutral Higgs decay to $b\bar{b}$. The alternative process $H^+W^-H^0$ is also included as a source of charged Higgs signal in the analysis having comparable cross-section. Read More

In this paper, the t-channel charged Higgs production at LHC is studied. Production process is a t-channel single top event with charged Higgs exchange. Therefore the signal is similar with Standard Model single top production in terms of the final state. Read More

One key requirement for fountain (rateless) coding schemes is to achieve a high intermediate symbol recovery rate. Recent coding schemes have incorporated the use of a feedback channel to improve intermediate performance of traditional rateless codes; however, these codes with feedback are designed based on uniformly at random selection of input symbols. In this paper, on the other hand, we develop feedback-based fountain codes with dynamically-adjusted nonuniform symbol selection distributions, and show that this characteristic can enhance the intermediate decoding rate. Read More

Many communication systems involve high bandwidth, while sparse, radio frequency (RF) signals. Working with high frequency signals requires appropriate system-level components such as high-speed analog-to-digital converters (ADC). In particular, an analog signal should be sampled at rates that meet the Nyquist requirements to avoid aliasing. Read More

In order to utilize network resources and provide a more reliable delivery of information, multipath routing algorithms are used with a higher priority than single path routing. But providing the quality of service (QoS) requirements while load balancing is done among multiple paths is still a challenge. In this paper a new load balancing algorithm is proposed by using an explicit endpoint admission control (EEAC) to achieve a dynamic load balancing algorithm, with the ability to guarantee the end-to-end QoS for a variety of service classes. Read More

In the present work, we revisit the process of gravitational collapse of a spherically symmetric homogeneous dust fluid which is known as the Oppenheimer-Snyder (OS) model [1]. We show that such a scenario would not end in a spacetime singularity when the spin degrees of freedom of fermionic particles within the collapsing cloud are taken into account. To this purpose, we take the matter content of the stellar object as a homogeneous Weyssenhoff fluid which is a generalization of perfect fluid in general relativity (GR) to include the spin of matter. Read More

The search for the heavy charged Higgs (mH+ > mtop) has been mainly based on the off-shell top pair production process. However, resonance production in s-channel single top events is an important channel to search for this particle. In a previous work, it was shown that this process, i. Read More

In this paper the triple Higgs production in a general two Higgs doublet model (2HDM) is studied. The production process is e+e- -> H+H-H0 followed by the charged Higgs decay to a pair of tau nu and the neutral Higgs decay to bb. The alternative process H+W-H0 is also included as a source of charged Higgs signal in the analysis. Read More

In this paper, charged Higgs pair production through $\ell^+ \ell^- \rightarrow H^+ H^-$ where $\ell = e$ or $\mu$, is studied within the framework of a general Two Higgs Doublet Model (2HDM). The analysis is relevant to a future $e^+e^-$ or $\mu^+\mu^-$ collider operating at center of mass energy of $\sqrt{s}=500$ GeV. Two different scenarios of small and large $\alpha$ values is studied. Read More

The charged Higgs bosons can be produced as a resonance in s-channel single top events. The light charged Higgs in such events preferably decays to a pair of $\tau \nu$ thus making it difficult to distinguish from the large single W events producing the same final state. However, the heavy charged Higgs decay to a pair of $t \bar{b}$ can be extracted from the SM background events. Read More

The aim of this work is to model the evolution of the cosmic space based on thermodynamical parameters. The universe is considered to have an apparent horizon radius with a Kodama-Hayward temperature assigned to it. The method is founded on the fact proposed by Padmanabhan [1,2] that the subtraction of the surface and bulk degrees of freedom provides information on the cosmic space emergence. Read More

In this study, an analytical solution is presented for thermo-electro-elastic analysis of piezoelectric semi-infinite bodies. For this purpose, governing equations are derived for a transversely isotropic piezoelectric material under axisymmetric thermo-electro-mechanical loading condition. A general closed form analytical solution is presented for the complementary and particular parts of the components of displacement vector and also electric potential function. Read More

The single top production proceeds through different channels at LHC. The t-channel production which has a cross section at the level of one third of the ttbar, can be regarded as a source of light charged Higgs boson through top quark decay to charged Higgs. Due to the low jet multiplicity and characteristic kinematic features of this process, a signal selection can be designed to extract charged Higgs signal from the background processes. Read More

Active tuning and switching of electromagnetic properties of materials is of great importance for controlling their interaction with electromagnetic waves. Superconductors are the only natural materials that exhibit diamagnetic switching at their critical temperatures. Here, we demonstrate a new class of meta-surfaces with electrically-induced diamagnetic switching capability at room temperature. Read More

Service-Oriented Applications (SOA) are being regarded as the main pragmatic solution for distributed environments. In such systems, however each service responds the user request independently, it is essential to compose them for delivering a compound value-added service. Since, there may be a number of compositions to create the requested service, it is important to find one which its properties are close to user's desires and meet some non-functional constraints and optimize criteria such as overall cost or response time. Read More

Even though the terahertz spectrum is well suited for chemical identification, material characterization, biological sensing and medical imaging, practical development of these applications has been hindered by the attributes of terahertz sources, namely low output power and poor efficiency. Here, we demonstrate that use of plasmonic contact electrodes can significantly enhance the optical-to-terahertz conversion efficiency in a photoconductive terahertz emitter. The use of plasmonic contact electrodes offers nanoscale carrier transport path lengths for the photocarriers, enabling efficient collection of the majority of carriers in a sub-picosecond time-scale. Read More

Optimum Bayes estimator for General Gaussian Distributed (GGD) data in wavelet is provided. The GGD distribution describes a wide class of signals including natural images. A wavelet thresholding method for image denoising is proposed. Read More

The charged Higgs associated production with a W boson has a smooth cross section as a function of the charged Higgs mass at muon colliders. The cross section in Minimal Supersymmetric Standard Model is about 25fb in the range 200 GeV < mH < 400 GeV with tanbeta = 50. This is much larger than the corresponding cross section at an e+e- collider which reaches a fraction of femtobarn. Read More

The observability of a charged Higgs boson produced in association with a W boson at future muon colliders is studied. The analysis is performed within the MSSM framework. The charged Higgs is assumed to decay to tb and a fully hadronic final state is analyzed, i. Read More

In this work, we analyze the Born, Bogoliubov, Green, Kirkwood and Yvon (BBGKY) hierarchy of equations for describing the full time-evolution of a many-body fermionic system in terms of its reduced density matrices (at all orders). We provide an exhaustive study of the challenges and open problems linked to the truncation of such hierarchy of equations to make them practically applicable. We restrict our analysis to the coupled evolution of the one- and two-body reduced density matrices, where higher order correlation effects are embodied into the approximation used to close the equations. Read More

Charged Higgs phenomenology and detection chance at future linear colliders through the production process $e^{-}e^{+} \ra H^{+}H^{-} \ra \tau^{+}\nu \tau \bar{\nu}$ is studied. Both charged Higgs bosons are considered to decay to $\tau\nu$ and the hadronic decay of $\tau$ leptons is analyzed taking into account spin and kinematics effects using a proper simulation of the $\tau$ lepton decay. It is shown that within the MSSM framework, with \tanb = 10, a wide range of charged Higgs masses would have detectable signal beyond the $5\sigma$ statistical significance at linear colliders with $\sqrt{s} = 500$ and 1000 GeV. Read More

In this paper the charged Higgs signal through the decay to a pair of muon and neutrino (H -> mu nu) is analyzed. The analysis attempts to estimate the amount of muonic signal of the charged Higgs at LHC at a center of mass energy of 14 TeV. The signal process is the top quark pair production with one of the top quarks decaying to a charged Higgs (non SM anomalous top quark decay) and the other decaying to a W boson which is assumed to decay hadronically to two light jets. Read More

In carbon nanotubes, the most abundant defects, caused for example by irradiation or chemisorption treatments, are small perturbing clusters, i.e. bi-site defects, extending over both A and B sites. Read More

A recurrent loop consisting of a single neuron is considered which is influenced by a chemical excitatory delayed synaptic feedback. We show the response of the system is dependent to the duration of the activity of the synapse which is determined by the deactivation time constant of the synapse. We show that loops with slow synapses, those which the effect of the synaptic activation remains for time constants comparable to the period of firing, show more predictable results where the effect of the fast synapses is tightly dependent on the loop delay time. Read More

Recently a model has been proposed that links dark matter and neutrino masses. The dark matter candidate which is dubbed as SLIM has a mass of MeV scale and can show up at low energy experiments. The model also has a high energy sector which consists of a scalar doublet, $(\phi^-, \phi^0)$. Read More

Possibility of observing associated production of charged Higgs and W boson in the framework of MSSM at LHC is studied. Both leptonic and hadronic decays of W boson are studied while the charged Higgs boson is considered to decay to a $\tau$ lepton and a neutrino. Therefore two search categories are defined based on the leptonic and hadronic final states, i. Read More

A denoising technique based on noise invalidation is proposed. The adaptive approach derives a noise signature from the noise order statistics and utilizes the signature to denoise the data. The novelty of this approach is in presenting a general-purpose denoising in the sense that it does not need to employ any particular assumption on the structure of the noise-free signal, such as data smoothness or sparsity of the coefficients. Read More

The search for MSSM Higgs bosons will be an important goal at the LHC. In order to analyze the search reach of the CMS experiment for the charged MSSM Higgs bosons, we combine the latest results for the CMS experimental sensitivities based on full simulation studies with state-of-the-art theoretical predictions of MSSM Higgs-boson production and decay properties. The experimental analyses are done assuming an integrated luminosity of 30 fb^-1 for the two cases M_H+- < m_t and M_H+- > m_t. Read More

In this report the CMS potential for the light charged Higgs boson discovery in the Minimal Supersymmetric Standard Model is presented. First the latest results of the Tevatron and LEP experiments on the light charged Higgs search are reminded. In the rest of the report the perspectives of CMS for the light charged Higgs search are presented with description of some details of the analysis. Read More

The achievable tanbeta determination accuracy for CMS at LHC is presented. Using MSSM H/A->tau tau decay in the associated production process gg->bbH/A the event rates are measured at large tanbeta and the systematic and statistical errors are estimated. Due to sensitivity of the above event rates to tanbeta it is shown that it is possible to determine constraints on tanbeta for a given set of SUSY parameters and uncertainties. Read More