Raising the Higgs mass with Yukawa couplings for isotriplets in vector-like extensions of minimal supersymmetry

Extra vector-like matter with both electroweak-singlet masses and large Yukawa couplings can significantly raise the lightest Higgs boson mass in supersymmetry through radiative corrections. I consider models of this type that involve a large Yukawa coupling between weak isotriplet and isodoublet chiral supermultiplets. The particle content can be completed to provide perturbative gauge coupling unification, in several different ways. The impact on precision electroweak observables is shown to be acceptably small, even if the new particles are as light as the current experimental bounds of order 100 GeV. I study the corrections to the lightest Higgs boson mass, and discuss the general features of the collider signatures for the new fermions in these models.Comment: 30 page

Collider Signature of T-quarks

Little Higgs models with T Parity contain new vector-like fermions, the T-odd quarks or "T-quarks", which can be produced at hadron colliders with a QCD-strength cross section. Events with two acoplanar jets and large missing transverse energy provide a simple signature of T-quark production. We show that searches for this signature with the Tevatron Run II data can probe a significant part of the Little Higgs model parameter space not accessible to previous experiments, exploring T-quark masses up to about 400 GeV. This reach covers parts of the parameter space where the lightest T-odd particle can account for the observed dark matter relic abundance. We also comment on the prospects for this search at the Large Hadron Collider (LHC).Comment: 5 pages, 3 figure

Constraining Light Colored Particles with Event Shapes

Using recently developed techniques for computing event shapes with Soft-Collinear Effective Theory, LEP event shape data is used to derive strong model-independent bounds on new colored particles. In the effective field theory computation, colored particles contribute in loops not only to the running of alpha_s but also to the running of hard, jet and soft functions. Moreover, the differential distribution in the effective theory explicitly probes many energy scales, so event shapes have strong sensitivity to new particle thresholds. Using thrust data from ALEPH and OPAL, colored adjoint fermions (such as a gluino) below 51.0 GeV are ruled out to 95% confidence level. This is nearly an order-of-magnitude improvement over the previous model-independent bound of 6.3 GeV.Comment: 4 pages, 2 figure

Completeness for a First-order Abstract Separation Logic

Existing work on theorem proving for the assertion language of separation logic (SL) either focuses on abstract semantics which are not readily available in most applications of program verification, or on concrete models for which completeness is not possible. An important element in concrete SL is the points-to predicate which denotes a singleton heap. SL with the points-to predicate has been shown to be non-recursively enumerable. In this paper, we develop a first-order SL, called FOASL, with an abstracted version of the points-to predicate. We prove that FOASL is sound and complete with respect to an abstract semantics, of which the standard SL semantics is an instance. We also show that some reasoning principles involving the points-to predicate can be approximated as FOASL theories, thus allowing our logic to be used for reasoning about concrete program verification problems. We give some example theories that are sound with respect to different variants of separation logics from the literature, including those that are incompatible with Reynolds's semantics. In the experiment we demonstrate our FOASL based theorem prover which is able to handle a large fragment of separation logic with heap semantics as well as non-standard semantics.Comment: This is an extended version of the APLAS 2016 paper with the same titl

Top quark physics in hadron collisions

The top quark is the heaviest elementary particle observed to date. Its large mass makes the top quark an ideal laboratory to test predictions of perturbation theory concerning heavy quark production at hadron colliders. The top quark is also a powerful probe for new phenomena beyond the Standard Model of particle physics. In addition, the top quark mass is a crucial parameter for scrutinizing the Standard Model in electroweak precision tests and for predicting the mass of the yet unobserved Higgs boson. Ten years after the discovery of the top quark at the Fermilab Tevatron top quark physics has entered an era where detailed measurements of top quark properties are undertaken. In this review article an introduction to the phenomenology of top quark production in hadron collisions is given, the lessons learned in Tevatron Run I are summarized, and first Run II results are discussed. A brief outlook to the possibilities of top quark research a the Large Hadron Collider, currently under construction at CERN, is included.Comment: 84 pages, 32 figures, accepted for publication by Reports on Progress in Physic

Влияние параметров аналого-цифрового преобразования и децимации на отношение сигнал/помеха в радиолокационном тракте

Introduction. The digital representation of received radar signals has provided a wide range of opportunities for their processing. However, the used hardware and software impose some limits on the number of bits and sampling rate of the signal at all conversion and processing stages. These limitations lead to a decrease in the signal-to-interference ratio due to quantization noise introduced by powerful components comprising the received signal (interfering reflections; active noise interference), as well as the attenuation of a low-power reflected signal represented by a limited number of bits. In practice, the amplitude of interfering reflections can exceed that of the signal reflected from the target by a factor of thousands.Aim. In this connection, it is essential to take into account the effect of quantization noise on the signal-tointerference ratio.Materials and methods. The article presents expressions for calculating the power and power spectral density (PSD) of quantization noise, which take into account the value of the least significant bit of an analog-to-digital converter (ADC) and the signal sampling rate. These expressions are verified by simulating 4-, 8- and 16-bit ADCs in the Mathcad environment.Results. Expressions are derived for calculating the quantization noise PSD of interfering reflections, which allows the PSD to be taken into account in the signal-to-interference ratio at the output of the processing chain. In addition, a comparison of decimation options (by discarding and averaging samples) is performed drawing on the estimates of the noise PSD and the signal-to-noise ratio.Conclusion. Recommendations regarding the ADC bit depth and sampling rate for the radar receiver are presented.Введение. Представление принятого радиолокационного сигнала в цифровом виде открыло широкие возможности в его обработке. Однако аппаратно-программные средства устанавливают ограничения на количество разрядов и частоту следования отсчетов сигнала на всех этапах преобразования и обработки. Эти ограничения приводят к снижению отношения сигнал/помеха из-за появления шумов квантования мощных составляющих принятого сигнала (мешающих отражений, активных шумовых помех), а также ослабления маломощного отраженного сигнала при представлении ограниченным количеством разрядов. На практике амплитуда мешающих отражений может в тысячи раз превышать амплитуду сигнала, отраженного от объекта радиолокации.Цель работы. Учет влияния шумов квантования на отношение сигнал/помеха в радиолокационном тракте.Материалы и методы. В статье представлены выражения для расчета мощности и спектральной плотности мощности шумов квантования, которые учитывают влияние цены младшего разряда аналого-цифрового преобразователя (АЦП) и частоты дискретизации сигнала. Выражения верифицированы путем моделирования АЦП в среде Mathcad для 4, 8 и 16 разрядов.Результаты. Разработаны основы методического аппарата в приложении к радиолокации, позволяющие рассчитывать спектральную плотность мощности шумов квантования мешающих отражений и учитывать ее в отношении сигнал/помеха на выходе тракта обработки. На основе оценок спектральной плотности мощности шумов и отношения сигнал/шум сопоставлены варианты децимации (прореживание и усреднение отсчетов).Заключение. Представлены рекомендации по выбору разрядности и частоты дискретизации АЦП для приемного радиолокационного тракта

Способ когерентной компенсации боковых лепестков спектра мешающих отражений в задаче обнаружения малоскоростных и малозаметных объектов

The detection of low-speed objects is a challenging task. The small radar cross-section of low-speed objects varying from one-thousandths to one-tens of a square meter practically excludes a successful detection of such objects against intense clutter from static objects by existing methods. In this work we present a method of coherent compensation of clutter from static objects in the sidelobes of the spectrum. The method provides successful detection of low-speed and low-visibility objects with reflective characteristics that create signals with power comparable to the power of spectral sidelobes of the clutter. The method is based on the representation of the side lobes of the spectrum of interfering reflections not in the form of noise, which determines the limiting level of “background whitening”, but in the form of a coherent spectral structure, amenable to further compensation. The proposed method must be especially effective in complicated situations such as when detecting signals reflected from low-speed and low-visibility objects (e.g., quadcopters) versus intensive clutter reflections from metal structures and buildings.Обнаружение малоскоростных объектов – сложная задача. Малая эффективная отражающая поверхность малоскоростных объектов, составляющая десятые – тысячные доли квадратного метра, практически исключает успешное решение задачи обнаружения их на фоне интенсивных мешающих отражений от местных предметов существующими методами. В статье представлен способ когерентной компенсации мешающих отражений от местных предметов в области боковых лепестков спектра. Способ обеспечивает успешное обнаружение малоскоростных и малозаметных объектов с отражательными характеристиками, создающими сигналы, сопоставимые по мощности с боковыми лепестками спектра отражений от местных предметов. Метод основывается на представлении боковых лепестков спектра мешающих отражений не в виде шума, определяющего предельный уровень «обеливания фона», а в виде когерентной спектральной структуры, поддающейся дальнейшей компенсации. Способ особенно эффективен в сложной ситуации – при выделении сигналов, отраженных от малоскоростных и малозаметных объектов (например, квадрокоптеров), на фоне интенсивных мешающих отражений от металлоконструкций и зданий

Cellular localization, accumulation and trafficking of double-walled carbon nanotubes in human prostate cancer cells

Carbon nanotubes (CNTs) are at present being considered as potential nanovectors with the ability to deliver therapeutic cargoes into living cells. Previous studies established the ability of CNTs to enter cells and their therapeutic utility, but an appreciation of global intracellular trafficking associated with their cellular distribution has yet to be described. Despite the many aspects of the uptake mechanism of CNTs being studied, only a few studies have investigated internalization and fate of CNTs inside cells in detail. In the present study, intracellular localization and trafficking of RNA-wrapped, oxidized double-walled CNTs (oxDWNT–RNA) is presented. Fixed cells, previously exposed to oxDWNT–RNA, were subjected to immunocytochemical analysis using antibodies specific to proteins implicated in endocytosis; moreover cell compartment markers and pharmacological inhibitory conditions were also employed in this study. Our results revealed that an endocytic pathway is involved in the internalization of oxDWNT–RNA. The nanotubes were found in clathrin-coated vesicles, after which they appear to be sorted in early endosomes, followed by vesicular maturation, become located in lysosomes. Furthermore, we observed co-localization of oxDWNT–RNA with the small GTP-binding protein (Rab 11), involved in their recycling back to the plasma membrane via endosomes from the trans-golgi network

General-elimination stability

General-elimination harmony articulates Gentzen's idea that the elimination-rules are justified if they infer from an assertion no more than can already be inferred from the grounds for making it. Dummett described the rules as not only harmonious but stable if the E-rules allow one to infer no more and no less than the I-rules justify. Pfenning and Davies call the rules locally complete if the E-rules are strong enough to allow one to infer the original judgement. A method is given of generating harmonious general-elimination rules from a collection of I-rules. We show that the general-elimination rules satisfy Pfenning and Davies' test for local completeness, but question whether that is enough to show that they are stable. Alternative conditions for stability are considered, including equivalence between the introduction- and elimination-meanings of a connective, and recovery of the grounds for assertion, finally generalizing the notion of local completeness to capture Dummett's notion of stability satisfactorily. We show that the general-elimination rules meet the last of these conditions, and so are indeed not only harmonious but also stable.Publisher PDFPeer reviewe

Bottom-quark fragmentation: comparing results from tuned event generators and resummed calculations

We study bottom-quark fragmentation in e+e- annihilation, top and Higgs decay H -> b bbar, using Monte Carlo event generators, as well as calculations, based on the formalism of perturbative fragmentation functions, which resum soft- and collinear-radiation effects in the next-to-leading logarithmic approximation. We consider the PYTHIA and HERWIG generators, and implement matrix-element corrections to the parton shower simulation of the H -> b bbar process in HERWIG. We tune the Kartvelishvili, string and cluster models to B-hadron data from LEP and SLD, and present results in both x_B and moment spaces. The B-hadron spectra yielded by HERWIG, PYTHIA and resummed calculations show small discrepancies, which are due to the different approaches and models employed and to the quality of the fits to the e+e- data.Comment: 22 pages, 11 colour figures. Minor changes in the text, published versio