130,137 research outputs found

    Modern Physics Simulations

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    Modern physics is now a regular course for non-physics majors who do not have to take the accompanying laboratory. This lack of an experimental component puts the engineering students at a disadvantage. A possible solution is the use of computer simulations to add a constructivist element to the class. In this work, we present a set of computer simulations of fundamental experiments, a key to the teaching of modern physics, as well as their in-class implementation and assessment. Preliminary results indicate that the use of these simulations produces a substantial increase in student comprehension.Comment: 11 pages, six figure

    The Ruds value in the vicinity of ψ(3770) state

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    The anomalous line shape of the ψ(3770) state has resulted in some difficulty in the determination of the R value for the continuum light hadron production in the resonance energy range. We parameterize the asymmetric line shape using a Fano-type formula and extract the Ruds value to be 2.156±0.022 from the data of BESIII Collaboration in the energy region between 3.650 and 3.872 GeV. The small discrepancy between experiment and theory is removed. The cross sections of the e+e−→hadrons with continuum light hadron production subtracted are given and compared to the data of the e+e−→DD¯ reaction

    Anomalous properties of spin-extended chiral fermions

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    The spin-extended semiclassical chiral fermion (we call the S-model), which had been used to derive the twisted Lorentz symmetry of the “spin-enslaved” chiral fermion (we call the c-model) is equivalent to the latter in the free case, however coupling to an external electromagnetic field yields nonequivalent systems. The difference is highlighted by the inconsistency of spin enslavement within the spin-extended framework. The S-model exhibits nevertheless similar though slightly different anomalous properties as the usual c-model does. The natural Poincaré symmetry of the free model remains unbroken if the Pfaffian invariant vanishes, i.e., when the electric and magnetic fields are orthogonal, E⋅B=0 as in the Hall effect

    General tree-level amplitudes by factorization limits

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    To find boundary contributions is a rather difficult problem when applying the BCFW recursion relation. In this paper, we propose an approach to bypass this problem by calculating general tree amplitudes that contain no polynomial using factorization limits. More explicitly, we construct an expression iteratively, which produces the correct factorization limits for all physical poles, and does not contain other poles, then it should be the correct amplitude. To some extent, this approach can be considered as an alternative way to find boundary contributions. To demonstrate our approach, we present several examples: ϕ4 theory, pure gauge theory, Einstein–Maxwell theory, and Yukawa theory. While the amplitude allows the existence of polynomials which satisfy the correct mass dimension and helicities, this approach is not applicable to determining the full amplitude

    Recursion relation for boundary contribution

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    It is well known that under a BCFW-deformation, there is a boundary contribution when the amplitude scales as O z 0 O(z0) \mathcal{O}\left({z}^0\right) or worse. We show that boundary contributions have a similar recursion relation as scattering amplitude. Just like the BCFW recursion relation, where scattering amplitudes are expressed as the products of two on-shell subamplitudes (plus possible boundary contributions), our new recursion relation expresses boundary contributions as products of sub-amplitudes and boundary contributions with less legs, plus yet another possible boundary contribution. In other words, the complete scattering amplitude, including boundary contributions, can be obtained by multiple steps of recursions, unless the boundary contributions are still non-zero when all possible deformations are exploited. We demonstrate this algorithm by several examples. Especially, we show that for standard model like renormalizable theory in 4D, i.e., the theory including only gauge boson, fermions and scalars, the complete amplitude can always be computed by at most four recursive steps using our algorithm

    Relativistic mass and modern physics

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    At first sight, arguments for and against the notion of relativistic mass look like a notorious intra-Lilliputian quarrel between Big-Endians (those who broke their eggs at the larger end) and Little-Endians. However, upon closer inspection we discover that the relativistic mass notion is alien to the spirit of modern physics to a much greater extent than it seems. To demonstrate an abyss between the modern approach and archaic notions, in this paper we explore how the concept of mass is introduced in modern physics. This modern approach reveals a deep cohomological origin of mass.Comment: 13 pages, no figures. Title changed in the published version (without an entertaining part

    Time Contortions in Modern Physics

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    As a basis for epistemological study of ``time,'' we analyze three suspect phenomena introduced by modern physics: non-locality, asymmetric aging and advanced interaction. It is shown that all three arise in connection with what has to be taken as arbitrary ideosyncrasies in formulation. It is shown that minor changes result in internally consistent variations of both Quantum Mechanics and Special Relativity devoid of these phenomena. The reinterpretation of some experiments though to confirm the existence of non-locality and asymmetric aging is briefly considered and a possible test is proposed.Comment: 8 pg. RevTeX + 1 eps figur

    What happened to modern physics?

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    Relativity, Quantum Mechanics and Chaos theory are three of the most significant scientific advances of the 20th Century - each fundamentally changing our understanding of the physical universe. The authors ask why the UK National Curriculum in science almost entirely ignores them. Children and young people regularly come into contact with the language, concepts and implications of these theories through the media and through new technologies, and they are the basis of many contemporary scientific and technological developments. There is surely, therefore, an urgent need to include the concepts of '20th Century physics' within the curriculum

    Nuclear force and the EMC effect

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    A linear correlation is shown quantitatively between the magnitude of the EMC effect measured in electron deep inelastic scattering (DIS) and the nuclear residual strong interaction energy (RSIE) obtained from nuclear binding energy subtracting the Coulomb energy contribution. This phenomenological relationship is used to extract the size of in-medium correction (IMC) effect on deuteron and to predict the EMC slopes |dREMC/dx| of various nuclei. We further investigate the correlations between RSIE and other quantities which are related to the EMC effect. The observed correlations among RSIE, EMC slope and SRC ratio R2NNtotal/Nnp(S13) imply that the local nuclear environment drives the modification of quark distributions

    The Euler Legacy to Modern Physics

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    Particular families of special functions, conceived as purely mathematical devices between the end of XVIII and the beginning of XIX centuries, have played a crucial role in the development of many aspects of modern Physics. This is indeed the case of the Euler gamma function, which has been one of the key elements paving the way to string theories, furthermore the Euler-Riemann Zeta function has played a decisive role in the development of renormalization theories. The ideas of Euler and later those of Riemann, Ramanujan and of other, less popular, mathematicians have therefore provided the mathematical apparatus ideally suited to explore, and eventually solve, problems of fundamental importance in modern Physics. The mathematical foundations of the theory of renormalization trace back to the work on divergent series by Euler and by mathematicians of two centuries ago. Feynman, Dyson, Schwinger... rediscovered most of these mathematical "curiosities" and were able to develop a new and powerful way of looking at physical phenomena
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