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quantum-field-theory
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Fermat's principle in quantum gravitational optics
, Article Journal of Cosmology and Astroparticle Physics ; Volume 2008, Issue 5 , 2008 ; 14757516 (ISSN) ; Khoeini Moghaddam, S ; Nouri Zonoz, M ; Sharif University of Technology
2008
Abstract
Interactions incorporating the vacuum polarization effects in curved backgrounds modify the null cone structure in such a way that the photon trajectories would not be the space-time geodesics any longer. The gravitational birefringence introduced as a direct consequence of these effects will allow shifts in the photon velocities leading to polarization dependent superluminal propagation. Taking these effects into account, we study Fermat's principle in the context of the 1+3 (threading) formulation of the space-time decomposition. We find an expression for the modified space-time refractive index and show that it is proportional to the light cone correction to first order. Consequences of...
Inclusive b-jet production in pp collisions at √s = 7 TeV
, Article Journal of High Energy Physics ; Volume 2012, Issue 4 , 2012 ; 11266708 (ISSN) ; Khachatryan, V ; Sirunyan, A. M ; Tumasyan, A ; Adam, W ; Bergauer, T ; Dragicevic, M ; Ero, J ; Fabjan, C ; Friedl, M ; Fruhwirth, R ; Ghete, V. M ; Hammer, J ; Hoch, M ; Hormann, N ; Hrubec, J ; Jeitler, M ; Kiesenhofer, W ; Krammer, M ; Liko, D ; Mikulec, I ; Pernicka, M ; Rahbaran, B ; Rohringer, C ; Rohringer, H ; Schöfbeck, R ; Strauss, J ; Taurok, A ; Teischinger, F ; Wagner, P ; Waltenberger, W ; Walzel, G ; Widl, E ; Wulz, C. E ; Mossolov, V ; Shumeiko, N ; Gonzalez, J. S ; Bansal, S ; Benucci, L ; Cornelis, T ; De Wolf, E. A ; Janssen, X ; Luyckx, S ; Maes, T ; Mucibello, L ; Ochesanu, S ; Roland, B ; Rougny, R ; Selvaggi, M ; Van Haevermaet, H ; Van Mechelen, P ; Van Remortel, N ; Van Spilbeeck, A ; Blekman, F ; Blyweert, S ; DHondt, J ; Suarez, R.G ; Kalogeropoulos, A ; Maes, M ; Olbrechts, A ; Van Doninck, W ; Van Mulders, P ; Van Onsem, G.P ; Villella, I ; Charaf, O ; Clerbaux, B ; De Lentdecker, G ; Dero, V ; Gay, A. P. R ; Hammad, G. H ; Hreus, T ; Leonard, A ; Marage, P. E ; Thomas, L ; Vander Velde, C ; Vanlaer, P ; Wickens, J ; Adler, V ; Beernaert, K ; Cimmino, A ; Costantini, S ; Garcia, G ; Grunewald, M ; Klein, B ; Lellouch, J ; Marinov, A ; Mccartin, J ; Rios, A. A. O ; Ryckbosch, D ; Strobbe, N ; Thyssen, F ; Tytgat, M ; Vanelderen, L ; Verwilligen, P ; Walsh, S ; Yazgan, E ; Zaganidis, N ; Basegmez, S ; Bruno, G ; Ceard, L ; De Favereau De Jeneret, J ; Delaere, C ; Du Pree, T ; Favart, D ; Forthomme, L ; Giammanco, A ; Grégoire, G ; Hollar, J ; Lemaitre, V ; Liao, J ; Militaru, O ; Nuttens, C ; Pagano, D ; Pin, A ; Piotrzkowski, K ; Schul, N ; Beliy, N ; Caebergs, T ; Daubie, E ; Alves, G. A ; Martins Jr., M. C ; De Jesus Damiao, D ; Martins, T ; Pol, M.E ; Souza, M. H. G ; Aldá Jr., W. L ; Carvalho, W ; Custódio, A ; Da Costa, E. M ; De Oliveira Martins, C ; De Souza, S. F ; Figueiredo, D. M ; Mundim, L ; Nogima, H ; Oguri, V ; Da Silva, W. L. P ; Santoro, A ; Do Amaral, S. M. S ; Jorge, L. S ; Sznajder, A. A ; Anjos, T. S ; Bernardes, C. A ; Dias, F. A ; Tomei, T. R. F. P ; Gregores, E. M ; Lagana, C ; Marinho, F ; Mercadante, P. G ; Novaes, S. F ; Padula, S. S ; Genchev, V ; Iaydjiev, P ; Piperov, S ; Rodozov, M ; Stoykova, S ; Sultanov, G ; Tcholakov, V ; Trayanov, R ; Vutova, M ; Dimitrov, A ; Hadjiiska, R ; Karadzhinova, A ; Kozhuharov, V ; Litov, L ; Pavlov, B ; Petkov, P ; Bian, J. G ; Chen, G. M ; Chen, H. S ; Jiang, C. H ; Liang, D ; Liang, S ; Meng, X ; Tao, J ; Wang, J ; Wang, J ; Wang, X ; Wang, Z ; Xiao, H ; Xu, M ; Zang, J ; Zhang, Z ; Asawatangtrakuldee, C ; Ban, Y ; Guo, S ; Guo, Y ; Li, W ; Liu, S ; Mao, Y ; Qian, S. J ; Teng, H ; Wang, S ; Zhu, B ; Zou, W ; Cabrera, A ; Gomez Morenon,B ; Osorio Oliveros, A. F ; Sanabria, J. C ; Godinovic, N ; Lelas, D ; Plestina, R ; Polic, D ; Puljak, I ; Antunovic, Z ; Dzelalija, M ; Kovac, M ; Brigljevic, V ; Duric, S ; Kadija, K ; Luetic, J ; Morovic, S ; Attikis, A ; Galanti, M ; Mousa, J ; Nicolaou, C ; Ptochos, F ; Razis, P. A ; Finger, M ; Finger Jr., M ; Assran, Y ; Kamel, A. E ; Khalil, S ; Mahmoud, M. A ; Radi, A ; Hektor, A ; Kadastik, M ; Müntel, M ; Raidal, M ; Rebane, L ; Tiko, A ; Azzolini, V ; Eerola, P ; Fedi, G ; Voutilainen, M ; Czellar, S ; Harkonen, J ; Heikkinen, A ; Karimaki, V ; Kinnunen, R ; Kortelainen, M. J ; Lampen, T ; Lassila Perini, K ; Lehti, S ; Linden, T ; Luukka, P ; Mäenpaa, T ; Peltola, T ; Tuominen, E ; Tuominiemi, J ; Tuovinen, E ; Ungaro, D ; Wendland, L ; Banzuzi, K ; Korpela, A ; Tuuva, T ; Sillou, D ; Besancon, M ; Choudhury, S ; Dejardin, M ; Denegri, D ; Fabbro, B ; Faure, J. L ; Ferri, F ; Ganjour, S ; Givernaud, A ; Gras, P ; De Monchenault, G. H ; Jarry, P ; Locci, E ; Malcles, J ; Millischer, L ; Rander, J ; Rosowsky, A ; Shreyber, I ; Titov, M ; Baffioni, S ; Beaudette, F ; Benhabib, L ; Bianchini, L ; Bluj, M ; Broutin, C ; Busson, P ; Charlot, C ; Daci, N ; Dahms, T ; Dobrzynski, L ; Elgammal, S ; De Cassagnac, R. G ; Haguenauer, M ; Mine, P ; Mironov, C ; Ochando, C ; Paganini, P ; Sabes, D ; Salerno, R ; Sirois, Y ; Thiebaux, C ; Veelken, C ; Zabi, A ; Agram, J. L ; Andrea, J ; Bloch, D ; Bodin, D ; Brom, J. M ; Cardaci, M ; Chabert, E. C ; Collard, C ; Conte, E ; Drouhin, F ; Ferro, C ; Fontaine, J.-C ; Gele, D ; Goerlach, U ; Juillot, P ; Karim, M ; Le Bihan, A. C ; Van Hove, P ; Fassi, F ; Mercier, D ; Baty, C ; Beauceron, S ; Beaupere, N ; Bedjidian, M ; Bondu, O ; Boudoul, G ; Boumediene, D ; Brun, H ; Chasserat, J ; Chierici, R ; Contardo, D ; Depasse, P ; El Mamouni, H ; Falkiewicz, A ; Fay, J ; Gascon, S ; Gouzevitch, M ; Ille, B ; Kurca, T ; Le Grand, T ; Lethuillier, M ; Mirabito, L ; Perries, S ; Sordini, V ; Tosi, S ; Tschudi, Y ; Verdier, P ; Viret, S ; Lomidze, D ; Anagnostou, G ; Beranek, S ; Edelhoff, M ; Feld, L ; Heracleous, N ; Hindrichs, O ; Jussen, R ; Klein, K ; Merz, J ; Ostapchuk, A ; Perieanu, A ; Raupach, F ; Sammet, J ; Schael, S ; Sprenger, D ; Weber, H ; Wittmer, B ; Zhukov, V ; Ata, M ; Caudron, J ; Dietz Laursonn, E ; Erdmann, M ; Guth, A ; Hebbeker, T ; Heidemann, C ; Hoepfner, K ; Klimkovich, T ; Klingebiel, D ; Kreuzer, P ; Lanskey, D ; Lingemann, J ; Magass, C ; Merschmeyer, M ; Meyer, A ; Olschewski, M ; Papacz, P ; Pieta, H ; Reithler, H ; Schmitz, S. A ; Sonnenschein, L ; Steggemann, J ; Teyssier, D ; Weber, M ; Bontenackels, M ; Cherepanov, V ; Davids, M ; Flügge, G ; Geenen, H ; Geisler, M ; Ahmad, W. H ; Hoehle, F ; Kargoll, B ; Sharif University of Technology
2012
Abstract
The inclusive b-jet production cross section in pp collisions at a center-ofmass energy of 7TeV is measured using data collected by the CMS experiment at the LHC. The cross section is presented as a function of the jet transverse momentum in the range 18 < pT < 200 GeV for several rapidity intervals. The results are also given as the ratio of the b-jet production cross section to the inclusive jet production cross section. The measurement is performed with two different analyses, which differ in their trigger selection and b-jet identification: a jet analysis that selects events with a b jet using a sample corresponding to an integrated luminosity of 34 pb -1, and a muon analysis requiring a...
Analogies and Differences Between Auantum Mechanics and Quanmtum Field Theory (Causality and Locality)
, M.Sc. Thesis Sharif University of Technology ; Golshani, Mehdi (Supervisor)
Abstract
Causality and locality are two of the fundamental problems in physics and physicists have different interpretations of them. In new physics theories like Quantum mechanics and Quantum field theory, the main point of discussion is that whether these two theories are local and causal or not? In first chapter, we introduce the principle of causality. The second and third chapters cover causality in Quantum mechanics and Quantum field theory.The last chapter is about locality
Aspects of Entanglement in Quantum Field Theory and Quantum Gravity, using the Holography
, Ph.D. Dissertation Sharif University of Technology ; Arfaei, Hessamaddin (Supervisor) ; Mosaffa, Amir Esmaeil (Supervisor) ; Alishahiha, Mohsen (Co-Advisor)
Abstract
Entanglement is an immediate consequence of quantum mechanical pos- tulates and is thus an indispensable part of studying quantum systems. A very useful quantity which can appropriately quantify entanglement between the degrees of freedom of a composite quantum system is En- tanglement Entropy (EE).
Over the last few years, this subject has attracted a lot of interest both in QFT and in the context of holography. On the one hand, an intu- itive geometrical Holographic model for entanglement entropy has been proposed in the context of gauge/gravity duality, and on the other, var- ious issues concerning entanglement have been explored, e.g. in quan- tum computation, quantum information...
Over the last few years, this subject has attracted a lot of interest both in QFT and in the context of holography. On the one hand, an intu- itive geometrical Holographic model for entanglement entropy has been proposed in the context of gauge/gravity duality, and on the other, var- ious issues concerning entanglement have been explored, e.g. in quan- tum computation, quantum information...
A proposed mechanism for mind-brain interaction using extended Bohmian quantum mechanics in Avicenna's monotheistic perspective
, Article Heliyon ; Volume 5, Issue 7 , July , 2019 ; 24058440(ISSN) ; Golshani, M ; Jamali, Y ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
In quantum approaches to consciousness, the authors try to propose a model and mechanism for the mind-brain interaction using modern physics and some quantum concepts which do not exist in the classical physics. The independent effect of mind on the brain has been one of the challenging issues in the history of science and philosophy. In some recent mind-brain interaction models, the direct influence of mind on matter is either not accepted (as in Stapp's model) or not clear, and there have not been any clear mechanism for it (as in Penrose-Hameroff's model or in Eccles's model). In this manuscript we propose a model and mechanism for mind's effect on the matter using an extended Bohmian...
A proposed mechanism for mind-brain interaction using extended Bohmian quantum mechanics in Avicenna's monotheistic perspective
, Article Heliyon ; Volume 5, Issue 7 , 2019 ; 24058440 (ISSN) ; Golshani, M ; Jamali, Y ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
In quantum approaches to consciousness, the authors try to propose a model and mechanism for the mind-brain interaction using modern physics and some quantum concepts which do not exist in the classical physics. The independent effect of mind on the brain has been one of the challenging issues in the history of science and philosophy. In some recent mind-brain interaction models, the direct influence of mind on matter is either not accepted (as in Stapp's model) or not clear, and there have not been any clear mechanism for it (as in Penrose-Hameroff's model or in Eccles's model). In this manuscript we propose a model and mechanism for mind's effect on the matter using an extended Bohmian...
Anharmonic oscillator: A playground to get insight into renormalization
, Article European Journal of Physics ; Volume 42, Issue 5 , 2021 ; 01430807 (ISSN) ; Loran, F ; Sharif University of Technology
IOP Publishing Ltd
2021
Abstract
In the presence of interactions the frequency of a simple harmonic oscillator deviates from the noninteracting one. Various methods can be used to compute the changes to the frequency perturbatively. Some of them resemble the methods used in quantum field theory (QFT) where the bare values of the parameters of the theory run when an interaction is added. In this paper, we review some of these techniques and introduce some new ones in line with QFT methods. Moreover, we investigate the case of more than one oscillator to see how the frequencies of small oscillations change when non-linear terms are added to a linear system and observe an interesting beat phenomenon in degenerate coupled...
Some Innovations in Expantion of Causal Quantum Mechanics to Quantum Field Theory
, M.Sc. Thesis Sharif University of Technology ; Golshani, Mehdi (Supervisor)
Abstract
The advent of Quantum Mechanics in the beginning of twentieth century created a fundamental evolution on physics. The ability and performance of Quantum Mechanics in perception of natural phenomena have spread its penetration farther than physics and affected different realms of science, and especially Philosophy. As a result, several philosophic and logical principles defined according to the Quantum Mechanics, and also several of them were rejected because of their inconsistency with Quantum Mechanics. Since Quantum Mechanics was not flawless theory, some of these evolutions have created profound deviations in interpretation and perception of nature. One of these changes was denial of...
Repulsive Casimir Forces
, M.Sc. Thesis Sharif University of Technology ; Bahmanabadi, Mahmoud (Supervisor) ; Taghizadeh Firouzjaee, Javad (Supervisor)
Abstract
It is well known that the fluctuations of electromagnetic fields in vacuum or in material media depend on the boundary conditions imposed on the fields. This dependence gives rise to forces which are known as Casimir forces, acting on the boundaries. Casimir forces between similar and disjoint objects such as two conducting or dielectric bodies are known in most cases to be attractive.¬¬ These forces are sometimes viewed as the macroscopic consequence of Van der Waals and Casimir-Polder attraction between molecules. In this thesis at first, calculation of Casimir forces in simple models were demonstrated. Then Van der Waals and Casimir-Polder forces have been explained in a unified theory...
Beyond the Standard Model Concentrating on the Supersymmetry
, M.Sc. Thesis Sharif University of Technology ; Golshani, Mehdi (Supervisor)
Abstract
In this thesis, a general survey and reviewis done about the models that go beyond the standard model. Even it contains the great subjects like quantum gravity and alternative Quantum field theories. In addition to them, we concentrate on the supersymmetry that is one of the most important subjects in the beyond the standard model. Recently, the validityof supersymmetry has confronted a lot of controversy. This motivates reconsideration of many supersymmetric models. So we survey the main motivations and problems of the supersymmetry and finally we discuss some possible solutions to the problems
Quantum Simulation of Quantum Field Theory
, M.Sc. Thesis Sharif University of Technology ; Karimipour, Vahid (Supervisor) ; Raeisi, Sadegh (Supervisor)
Abstract
Physics underlies computer science because computation is a physical process. The fundamental question about computers is: What computations can be performed efficiently, and what computations are intractable? This is a question about the laws of physics and the consequences of those laws.Though we don’t know how to prove it from first principles,we have good reasons to believe that there are computational problems which are too hard to solve using digital computers based on classical physics, yet can be solved by computers which exploit quantum phenomena such as interference and entanglement. This is one of deepest distinctions ever made between classical and quantum physics, and it poses...
On Swampland Conjectures and Relations to Entropy of States
, M.Sc. Thesis Sharif University of Technology ; Torabian, Mahdi (Supervisor) ; Ashoorioon, Amjad (Co-Supervisor)
Abstract
In the framework of quantum field theory, countless consistent theories can be constructed. However, it is understood that only a small subset of these theories can be consistently embedded in a theory of quantum gravity (QG). In string theory, as the best candidate for quantum gravity, there is a landscape of effective field theories (EFTs) which are descended from some compactification of extra dimensions. EFTs which are not derived from a compactification is said to belong to swampland. From a bottom-up point of view, the aim of the swampland program is to find a list of criteria which an EFT must respect so that it survives the swampland. The trans-Planckian censorship conjecture (TCC)...
Vacuum of Classical Mechanic, Quantum Field and General Relativity
, M.Sc. Thesis Sharif University of Technology ; Golshani, Mehdi (Supervisor)
Abstract
The idea of "vacuum energy" with definition of the "Aether" has many historical backgrounds from Aristotelian philosophy to 19th century and the advent of quantum vacuum. Some assert vacuum which is defined as "pure void" and others have got contrary viewpoints. It can be said that the history of vacuum is as old as history of physics. With the advent of quantum mechanics, vacuum has taken a specific definition. Vacuum from vision of quantum mechanics describes that vacuum is the minimum possible energy state, because if the energy of "quantum vacuum state" became zero, Heisenberg uncertainty principle would be violated. The important consequence of quantum mechanics will be in apparent...
(Topological Quantum Field Theory (TQFT
, M.Sc. Thesis Sharif University of Technology ; Jafari, Amir (Supervisor)
Abstract
This thesis is about one of the newest attractive theories in mathematics and theoretical physics; Topological Quantum Field Theory (TQFT) has some basic algebraic requirements called tensor categories, after introducing them and describing axioms of the theory which has suggested by Atiyah in 1988, we will see that the category of 2d-TQFT is equivalent to the category of commutative frobenius algebras over an arbitrary field .In the last part we focus on some topological aspects of theory in dimension 3 and some invariants of 3d manifolds , we will see these invariants are the main tool for construction a 3d-TQFT
QFT in Curved Space-Time and it’s Applications in Cosmological Perturbation theory
, M.Sc. Thesis Sharif University of Technology ; Abolhassani, Ali Akbar (Supervisor) ; Sheikh Jabbari, Mohammad Mahdi (Co-Advisor)
Abstract
We know the matter can curve the space-time according to the general theory of relativity. On the other hand Quantum Field Theory has been formulated in a flat space-time and we cannot use most of its techniques within a curved space-time. Formulating the Quantum Field Theory in curved space-time is important for various subjects in physics like early universe or black hole physics. We will review the formulating QFT in cosmological background and will look for observable consequences on Cosmological Microwave Background in this thesis
A Survey in Inflation and Roots of Axionic Inflationary Models
,
M.Sc. Thesis
Sharif University of Technology
;
Abolhasani, Ali Akbar
(Supervisor)
Abstract
Inflation first introduced for solving the puzzles of the standard model of cosmology. Soon it became clear that this paradigm can provide a natural way for production of Initial conditions for the birth of large-scale structures: cosmological perturbations. But inflationary models are usually phenomenological models. They are constructed to solve the problems of the standard model of cosmology and explain the properties of cosmological fluctuations. Where do they come from? A property of a big family of inflationary models is the flatness of their potential. What would may be the cause of this flatness? . . .. In this thesis our purpose is searching about one probable field theoretic root...
An Expository Survey on Different Approaches to Quantum Gravity
, M.Sc. Thesis Sharif University of Technology ; Golshani, Mehdi (Supervisor) ; Azadegan, Ebrahim (Supervisor)
Abstract
The search for an empirically proven quantum theory of gravity is one of the greatest open problems of fundamental physics. Obstacles are formal and conceptual in nature. Our goal is to find a theory that somehow unites general relativity (Einstein's classical field gravity theory) and quantum field theory. In this research work, the problem of quantum gravity and the reason for its importance are investigated, as well as the proposed solutions; and what philosophical issues do these approaches and the issue itself create. Research has been carefully selected to remain managed in terms of size and content, however, some basic formalism is introduced to enter physics and the philosophy of...
Quantum Field Theory On Time-dependent Background: The Case Of Neutrino and Lepton Asymmetry Generation
, M.Sc. Thesis Sharif University of Technology ; Torabian, Mahdi (Supervisor)
Abstract
One of the open questions in particle physics and cosmology is matter-antimatter asymmetry in the Universe. Observations at different scales in the early universe indicates that the number of baryons and leptons are greater than the number of anti-baryons and anti-leptons. Various mechanisms in the last 50 years, have been proposed to generate this asymmetry from a symmetric Universe. They can be classified into two groups: models which add new particles and interactions and models which consider gravity and time dependent background fields. The basic difference is that if they respect CPT symmetry or not. In this thesis we take the second approach. We study the neutrino sector of the...
Investigation of Electron Tunneling Spectroscopy at Topological Superconductors Junctions
, M.Sc. Thesis Sharif University of Technology ; Kargarian, Mehdi (Supervisor)
Abstract
In this thesis, we study the tunneling transport at the interface of superconducting states in Bismuth-Nickel bilayer systems . The electron states on the surface of Bismuth are described by Dirac fermions due to strong inversion symmetry breaking near the surface and strong spin-orbit coupling . The magnetic fluctuations of underneath Nickel give rise to an attractive interaction between electron states of Bismuth and formation of superconducting states . The latter states cann't be described by conventional singlet and triplet pairing symmetries due to lack of spin degeneracy in Bismuth . In previous works, it's shown that the superconducting states break the time-reversal symmetry...