Top PDF Some topics in theoretical high-energy physics

Some topics in theoretical high-energy physics

Some topics in theoretical high-energy physics

At lowest order in QCD perturbation theory, e+e- annihilation proceeds - the final q,q- 'fragment' into two jets of hadrons with through e+e +y *+qq; At Oa , one of the outgoing quarks m[r]

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Topics in Theoretical Astrophysics

Topics in Theoretical Astrophysics

The main new results of the current work are as follows. By studying the properties of orbits in the strong field of the spacetime, we find that most geodesics in the spacetime appear to have a fourth isolating integral of the motion, in addition to the energy, angular momentum and rest mass that are guaranteed by the stationarity and axisymmetry of the metric. The corresponding orbits are triperiodic to high accuracy. This was not guaranteed, since the separability of the geodesic equations in Kerr and corresponding existence of a fourth integral (the Carter constant) was unusual. Additionally, we find that for some oblate perturbations of the Kerr spacetime, there are regions of the spacetime in which there appears to be no fourth integral, leading to ergodic motion. If observed, ergodicity would be a clear “smoking-gun” for a deviation from Kerr. Ergodic motion has been found in other exact relativistic spacetimes by other authors, although these investigations were not carried out in the context of their observable consequences for EMRI detections. Sota, Suzuki and Maeda [14] described chaotic motion in the Zipoy-Voorhees-Weyl and Curzon spacetimes; Letelier & Viera [15] found chaotic motion around a Schwarzschild black hole perturbed by gravitational waves; Gu´eron & Letelier observed chaotic motion in a black hole spacetime with a dipolar halo [16] and in prolate Erez-Rosen bumpy spacetimes [17]; and Dubeibe, Pachon, and Sanabria-Gomez found that some oblate spacetimes which are deformed generalizations of the Tomimatsu-Sato spacetime could also exhibit chaotic motion [18]. The new features of our current results are the presence of potentially ergodic regions for a wider range of magnitudes of the perturbation, and an examination of whether the ergodic regions are astrophysically relevant. We find that, in the context of an EMRI, the ergodic regions exist only very close to the central body, and these regions are probably not astrophysically accessible, at least in the Manko-Novikov spacetime family.
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Theory construction in high-energy particle physics

Theory construction in high-energy particle physics

In this dissertation I bridge the traditions of historically motivated philosophy of high- energy physics and foundational analysis of the theoretical framework. I examine the historical episodes (Chapters 2 and 3) or contemporary practices (Chapter 4) in detail, but the questions I am interested in answering should also be relevant to those more concerned with foundational analysis into the framework of high-energy physics. In Chapter 2 I discuss the problems with non-empirical confirmation (cf. Dawid [2013]), and suggest alternatives that may be tenable in today’s epistemic environment. I also comment on the prominent role of symmetries in the sparse theoretical framework of the 1950s, underscoring the continued relevance of sym- metries for naturalness arguments in high-energy physics today. Chapter 3 examines the role of formal analogies in the development of symmetry breaking and lattice quantum field the- ory, and connects the historical role of the importance of renormalizability with more modern views of the standard model as a collection of e ff ective field theories. Chapter 4 deals with precision testing of QED as a means to set narrow bounds on the possible variations of key parameters in the standard model. This will help to limit candidates in the search for future models seeking to go beyond the standard model. Looking at the history and practice of high- energy physics allows one to approach foundational issues in the philosophy of physics from a slightly di ff erent perspective. For example, the historical importance of renormalizability as a criterion for acceptable models of the strong and (electro)weak interactions contrasts heavily with the accepted contemporary view of the standard model as a set of e ff ective field theories. Those who take the contemporary view at face value miss out on the details and developments of renormalizability proofs that were instrumental to the emergence of the standard model. Dimensional regularization—the regularization method used to prove the renormalizability of massless Yang-Mills models with spontaneously broken gauge symmetry—is a powerful tool that is valuable outside of the context of renormalizability proofs. By paying attention to their historical role, one becomes aware of their existence, and potential use to remedy foundational issues present today.
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On the Need for Fractal Logic in High Energy Quantum Physics

On the Need for Fractal Logic in High Energy Quantum Physics

Modern advances in pure mathematics and particularly in transfinite set theory have introduced into the fundamentals of theoretical physics many novel concepts and devices such as fractal quasi manifolds with non-integer (Hausdorff) di- mension for its geometry as well as infinite dimensional wild topology and non classical fuzzy logic. In the present work transfinite fractal sets and fuzzy logic are combined to enable the introduction of a new theory termed fractal logic to the foundation of high energy particle physics. This leads naturally to a new look at quantum gravity. In particular we will show that to understand and develop quantum gravity we have to bring various fields together, particularly fractals and nonlinear dynamics as well as sphere packing, fuzzy set theory, number theory and quantum entanglement and irra- tionally q-deformed algebra.
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Neutrino Radiation Transport and Other Topics in High Energy Density Astrophysics

Neutrino Radiation Transport and Other Topics in High Energy Density Astrophysics

and a piece of poorly understood fundamental physics. While essential for much of astrophysics involving compact objects, we have only incomplete knowledge of the nuclear EOS. Uncertainties are particularly large at densities above a few times nuclear and in the transition regime between uniform and nonuniform nuclear matter at around nuclear saturation density J. M. Lattimer, 2012; Oertel et al., 2017. The nuclear EOS can be constrained by experiment (see J. M. Lattimer, 2012; Oertel et al., 2017 for recent reviews), through fundamental theoretical considerations (e.g., Hebeler et al., 2010; Hebeler et al., 2013; Kolomeitsev et al., 2016), or via astronom- ical observations of neutron star masses and radii (e.g., J. M. Lattimer, 2012; Nättilä et al., 2016; Özel and Freire, 2016). Gravitational wave (GW) observations Abbott, 2016b with advanced-generation detectors such as Advanced LIGO LIGO Scientific Collaboration et al., 2015, KAGRA Somiya (for the KAGRA collaboration), 2012, and Advanced Virgo Acernese et al. (Virgo Collaboration), 2009 open up another observational window for constraining the nuclear EOS. In the inspiral phase of neutron star mergers (including double neutron stars and neutron star – black hole binaries), tidal forces distort the neutron star shape. These distortions depend on the nuclear EOS. They measurably affect the late inspiral GW signal (e.g., Bernuzzi, Nagar, et al., 2012; Bernuzzi, Dietrich, and Nagar, 2015; Flanagan and Hinderer, 2008; Read et al., 2009). At merger, tidal disruption of a neutron star by a black hole leads to a sudden cut off of the GW signal, which can be used to constrain EOS properties Vallisneri, 2000; M. Shibata and Taniguchi, 2008; Read et al., 2009. In the double neutron star case, a hypermassive metastable or permanently stable neutron star remnant may be formed. It is triaxial and extremely efficiently emits GWs with characteristics (amplitudes, frequencies, time-frequency evolution) that can be linked to the nuclear EOS (e.g, Radice, Bernuzzi, et al., 2016; Bernuzzi, Radice, et al., 2016; Stergioulas, 2011; Bauswein and H.-T. Janka, 2012; Bauswein, Stergioulas, and H.-T. Janka, 2014).
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2009 European School of High-energy Physics

2009 European School of High-energy Physics

Relativistic quantum field theory is the adequate theoretical framework to formulate the commonly ac- cepted theory of the fundamental interactions, the Standard Model of the strong and the electroweak interactions [1–4]. The Standard Model summarizes our present knowledge of the basic constituents of matter and their interactions. It is a gauge invariant quantum field theory based on the symmetry group SU (3) × SU (2) × U (1), with the colour group SU(3) for the strong interaction and with SU (2) × U (1) for the electroweak interaction spontaneously broken by the Higgs mechanism. The renormalizability of this class of theories allows us to make precise predictions for measurable quantities also in higher orders of the perturbative expansion, in terms of a few input parameters. The higher-order terms contain the self-coupling of the vector bosons as well as their interactions with the Higgs field and the top quark, even for processes at lower energies involving only light fermions. Assuming the validity of the Stan- dard Model, the presence of the top quark and the Higgs boson in the loop contributions to electroweak observables allows us to obtain indirect significant bounds on their masses from precision measurements of these observables. The only unknown quantity at present is the Higgs boson. Its mass is getting more and more constrained by a comparison of the Standard Model predictions with the experimental data, preparing the ground for a crucial test at the LHC.
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Sizes and distances in high energy physics

Sizes and distances in high energy physics

The wave function is a solution of the Schr ¨ odinger equation with an appropriate instantaneous poten- tial. When coming to the relativistic domain the use of the instantaneous potential becomes problem- atic because of the retardation e ff ects. Nonetheless, Eq.(1) is being actively used for extracting from the data the "charge radius" of, say, the proton with further placing the result into the PDG Reviews as an important physical characteristic of the proton charge distribution. To avoid as much as possible the model dependence we first consider the formula (1) in the context of the general quantum-field theoretical expression via the Bogoliubov-LSZ reduction formalism. For simplicity but without loss of generality we consider the pion form factor F(q 2 ) defined as follows
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A comparison of learning high school modern physics topics based on two different curricula

A comparison of learning high school modern physics topics based on two different curricula

It is seen that both the chronological order and the mathematical equations and formula are frequently addressed in textbooks when the topics of modern physics are taught in Turkey. Research (Eryılmaz & Şen, 2010a; Eryılmaz & Şen, 2010b) highlight some of the difficulties that high school students experience in learning physics. For example, they often cannot relate the concepts of modern physics such as photon, photoelectron, spectrum, photoelectric effect, and ionization energy with formulas. Similarly, many high school students have issues exploring, restructuring, interpreting, and comparing modern physics with their previous primary education. It is also expected that teachers have adequate understanding of the topics that should be taught. However, no studies about teachers in the field of modern physics education in Turkey have been found. When those on modern physics or quantum physics in Turkey are examined (Altunsoy, 2012; Çalışkan, 2002; Didiş, 2012; Kurt 2010; Özdemir, 2008; Özcan, 2009, Şimşek, 2009; Yeşildağ, 2009), it is seen that these are mostly conducted on teacher candidates. In his studies on teacher candidates, Şen (2002a; 2002b) examined the misconceptions and mistakes that they made in quantum physics. He reported that senior teacher candidates still tend to be hinging on classical analogies that used Newtonian physics instead of modern physics’ way of thinking. He went on to note that their skills of understanding and expressing quantum physics were weaker than their mathematical skills.
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Topics in theoretical particle physics and cosmology

Topics in theoretical particle physics and cosmology

Nevertheless, the energy density at matter-radiation equality and the fraction of matter in baryons are relevant to anthropic constraints described in Sections 5.2.5 and 5.2.7. In addition, our assumption that the early universe is radiation dominated does not hold if ζ is too large. In this case, primordial black holes may dominate the energy density of the universe while baryons are still relativistic. Then all of the baryons would be redshifted away or swallowed into black holes. This possibility is studied at the end of this section. In the following we neglect the neutrino content of the universe. Their influence upon cosmology is commonly viewed as insignificant and we do not expect this to change since as a hot relic their density relative baryons is fixed. In addition, we assume the dark matter to be a WIMP. This allows for relatively precise predictions, as opposed to, for example, axion dark matter where the density is set by a stochastic variable [156]. (Note however that the stochastic nature of axion dark matter makes this possibility more flexible to anthropic selection, see for example Refs. [115, 117].)
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The Some Common Problems Of  High Energy Physics, Gravitation And Cosmology

The Some Common Problems Of High Energy Physics, Gravitation And Cosmology

All these bear strong resemblance to the situation with Ptolemaic models of Solar system before appearance of Kepler`s laws and Newton s mechanics. These earth-centered models of the planets movement in Solar system had required at first introduction of so called epicycles specially selected for the coordination of theoretical forecasts and observations. Its description of planets positions was quite good; but later to increase the forecasts accuracy it had required another bunch of additional epicycles. Good mathematicians know that epicycles are in fact analogues of Fourier coefficients in moment decomposition in accordance with Kepler`s laws; so by adding epicycles the accuracy of the Ptolemaic model can be increased too. However that does not mean that the Ptolemaic model is adequately describing the reality. Quite the contrary. Note the following remarkable fact: the standard theory allowed detecting spectra by using always the quantum equations with outer potential and as corollaries to geometric relations between de Broglie wave’s length and characteristic dimension of potential function. The quantum equation of our theory does not contain the outer potential and describe a particle in empty free space; the mass quantization arises owing to the delicate balance of dispersion and non-linearity which provides the stability of some wave packets number. It is the first case when spectra are detected by using the quantum equations without outer potential.
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The Lukewarm Frontier: Some Cosmological Consequences of 'Low Energy' Physics

The Lukewarm Frontier: Some Cosmological Consequences of 'Low Energy' Physics

The discovery of the cosmic acceleration [22–25] has prompted speculations of new physics. A leading hypothesis is the existence of a cosmological constant, responsible for the accelerated expansion. The milli-eV energy scale implied by this phenomenon is difficult to understand in terms of a fundamental theory [343–346]. The validity of Einstein’s general theory of relativity (GR) on cosmological scales has thus come under suspicion. A novel solution to this problem might be achieved if GR is a low- energy effective theory in which gravity weakens at some energy scale. In an effective theory of gravity there may exist a threshold, µ, beyond which gravitons cannot mediate momentum transfers. This behavior may be due to a “fat” graviton, a minimal length scale associated with quantum gravity, or possibly nonlinear effects which filter out high-frequency interactions [347–354]. Such theories offer a novel solution to the cosmological constant problem by regulating the contribution of vacuum fluctuations to the cosmological constant. However, we will show that this mechanism may have already been explored and ruled out by gravitational lensing on cosmological scales.
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A computing structure for data acquisition in high energy physics

A computing structure for data acquisition in high energy physics

link; procedure visit_callt: begin send now to visited node; while waiting if then val_requested link; to requesting send val receive node; new now from visited end;.. procedure visit an[r]

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A computing structure for data acquisition in high energy physics

A computing structure for data acquisition in high energy physics

input_parameters; procedure INITIALISE INPUT AND OUTPUT FILES READ IN THE PARAMETERS OF THE RING TO MODEL WRITES A HEADING TO STACKRECORD var l, r, n: integer; begin * INPUT PARAMETERS r[r]

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Nonextensive statistical mechanics: Applications to high energy physics

Nonextensive statistical mechanics: Applications to high energy physics

1), where W is the number of microscopic configurations of the system. This extremely powerful theory — one of the pillars of contemporary physics — has exhibited very many successes along 140 years, in particular through its celebrated distribution for thermal equilibrium p i ∝ e − βE i ,

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Evolution of the Hadoop Platform and Ecosystem for High Energy Physics

Evolution of the Hadoop Platform and Ecosystem for High Energy Physics

By combining multiple infrastructures and systems developed at CERN and already reported in this paper, notably Hadoop platform, with SWAN service, Kubernetes and EOS storage we achieved a modern, powerful and scalable platform for data analysis and analytics. The full architecture and interaction between the platform components are illustrated in Figure 2. One of the key features of the platform is usage simplicity - by facing Jupyter Notebooks (via SWAN service), users can easily develop, execute and share their code. All the submit- ted workloads are automatically distributed by Spark to the multiple machines or containers of a Hadoop or Kubernetes cluster. User depending on required computing resources can specify to use either of them. We expect that for frequent, IO and computing intensive pro- duction workloads with a need for deterministic time to complete users will continue to profit of Hadoop clusters and HDFS storage. For ad-hoc use cases or heavy compute-intensive workloads (like physics data reduction), that cannot be satisfied by the resource available in Hadoop service using Spark on Kubernetes can provide a better option. No matter which cluster manager is used for execution of a Spark job, it can access data on EOS or HDFS or both at the same time.
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ATLAS and ultra high energy cosmic ray physics

ATLAS and ultra high energy cosmic ray physics

rule out the hypothesis that the knee in the cosmic ray spectrum is due to the effect of some new hadronic physics threshold, where some 20% of the cosmic ray primary energy would need to be transferred to invisible channels. Future ATLAS running at 13 TeV will allow us to further refine our hadronic interaction models. Importantly the turn on of the AFP detector will enable important studies of single and double diffraction, a key input to our overall understanding of hadronic physics at the LHC. Last, but not least, the use of the ATLAS detector as a high precision cosmic-muon observatory would enable the LHC to contribute directly to our understanding of high energy cosmic ray physics across the knee region of the cosmic ray energy spectrum.
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Wireless data transmission for high energy physics applications

Wireless data transmission for high energy physics applications

Today, readout systems typically use wired optical data transmission for data rates beyond 1 Gb / s per channel. However, radiation hardness issues, space and power constraints limit the usage of optical components in very dense pixel detector environments to places far outside the active volume. This is the case, for instance, for the vertex detector for the Phase-II upgrade of the ATLAS Inner Tracker (ITk) [1]. In these cases, wired copper transmission lines are used to transfer the data over several metres towards the optical drivers. Aiming for very high data rates, copper based transmission lines typically suffer from an increased impedance which limits the transmission of data rates of a few Gb/s to distances of a few metres. Developments in both wired optical and copper technologies are on- going, but a third, alternative technology relying on wireless data transmission might be attractive for future high rate readout systems in dense and hostile environments, as first described in [2]. Regarding bandwidth, wireless technologies have caught up and can deliver rates in the range of several gigabits per second, as well.
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The TrackML high-energy physics tracking challenge on Kaggle

The TrackML high-energy physics tracking challenge on Kaggle

Particle physics events contain a multitude of different types of information that are usu- ally represented in a nested structures of variable length. Here, we aim to provide the data in a flattened structure to avoid the necessity for specialised tools or formats. Since events are statistically independent, data is stored separately for each event, organized by a numerical event identifier. For each event in the training dataset the following four files are provided: Hits: The hits file provides the simulated hit information that are the core input for the chal- lenge. Each entry corresponds to one hit generated by one particle in a detector module. Hits are identified by an event-unique numerical identifier. The position of the hit in the global coordinate system (x, y, z) as well as its origin in the detector hierarchy, i.e. volume, layer, and module identifier, is given.
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Harnessing the QCD power spectrum for high energy physics

Harnessing the QCD power spectrum for high energy physics

The number of prongs in a fit is related to the number of uniquely resolvable directions of collimated hard radiation, while the prong mass produces a shape that is related to the accompanying soft radiation. We have examined fits to two jet-like and three jet-like events, and find that we generally minimize the χ 2 with two prongs per hard jet-like object. It is important to realize we are not calculating “jets” in the standard sense — asymptotic objects with finite radius. Instead, every power jet includes a contribution from the full energy and angle-weighted correlation information in the event. We are extracting all of the QCD radia- tion that resulted from the hard underlying interaction, not cutting out a small region of phase space. This has several useful consequences.
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Some topics in the theory of supermanifolds

Some topics in the theory of supermanifolds

[27], Berezin & Kac [5] and Berezin & Leites [6] in which the sheaf of C" functions is enlarged to include anticommuting elements and secondly the theory of supermanifolds due to Rogers [34], [35], [36], deWitt [47] and Batchelor [3] in which a manifold is modelled on the local structure of an exterior algebra. The structure of graded manifolds has been investigated in some detail (see [2], [7], [16], [18] and [29]) with the conclusion that these objects are basically given by the sheaf of sections of the exterior bundle of some vector bundle over a C* manifold. Recently, attention has been turned to the topological structure of supermanifolds, since it is not at all clear when a C** manifold can admit the structure of a supermanifold. It is fairly easily established that Rogers' supermanifolds [34], are multifoliate in the sense of Kodaira & Spencer [26],
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