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| 2. |
- Beisert, Niklas, et al.
(författare)
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Review of AdS/CFT Integrability : An Overview
- 2012
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Ingår i: Letters in Mathematical Physics. - : Springer Science and Business Media LLC. - 0377-9017 .- 1573-0530. ; 99:1-3, s. 3-32
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Forskningsöversikt (refereegranskat)abstract
- This is the introductory chapter of a review collection on integrability in the context of the AdS/CFT correspondence. In the collection we present an overview of the achievements and the status of this subject as of the year 2010.
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| 4. |
- Freyhult, Lisa, 1977-
(författare)
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Aspects of Yang-Mills Theory : Solitons, Dualities and Spin Chains
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- One of the still big problems in the Standard Model of particle physics is the problem of confinement. Quarks or other coloured particles have never been observed in isolation. Quarks are only observed in colour neutral bound states. The strong interactions are described using a Yang-Mills theory. These type of theories exhibits asymptotic freedom, i.e. the coupling is weak at high energies. This means that the theory is perturbative at high energies only. Understanding quark confinement requires knowledge of the non perturbative regime. One attempt has been to identify the proper order parameters for describing the low energy limit and then to write down effective actions in terms of these order parameters. We discuss one possible scenario for confinement and the effective models constructed with this as inspiration. Further we discuss solitons in these models and their properties.Yang-Mills theory has also become important in the context of string theory. According to the AdS/CFT correspondence string theory in AdS5×S5 is dual to four dimensional Yang-Mills with four supersymmetries. The duality relate the non perturbative regime of one of the theories to the perturbative regime of the other. This makes it in general hard to test this conjecture. For a special type of solutions it is however possible to use a perturbative expansion in both theories. We discuss this type of solutions and in particular we discuss a method, the Bethe ansatz, to find the solutions on the gauge theory side.
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| 6. |
- Freyhult, Lisa, 1977-
(författare)
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Generalised scaling at subleading order
- 2012
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Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; :1, s. 26-
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Tidskriftsartikel (refereegranskat)abstract
- We study operators in the sl(2) sector of N=4 SYM in the generalised scaling limit, where the spin is large and the length of the operator scales with the logarithm of the spin. At leading order in the large spin expansion the scaling dimension at strong coupling is given in terms of the free energy of the O(6) model. We investigate the first subleading corrections to the scaling dimension and find that these too can be derived from the O(6) model in the strong coupling limit.
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| 10. |
- Freyhult, Lisa, 1977-
(författare)
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Review of AdS/CFT Integrability, Chapter III.4 : Twist states and the cusp anomalous dimension
- 2012
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Ingår i: Letters in Mathematical Physics. - : Springer Science and Business Media LLC. - 0377-9017 .- 1573-0530. ; 99:1-3, s. 255-276
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Forskningsöversikt (refereegranskat)abstract
- We review the computation of the anomalous dimension of twist operators in the planar limit of N=4 SYM using the asymptotic Bethe ansatz and demonstrate how this quantity is obtained at weak, strong and intermediate values of the coupling constant. The anomalous dimension of twist operators in the limit of large Lorentz spin played a major role in the construction as well as in many tests of the asymptotic Bethe equations, this aspect of the story is emphasised.
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| 11. |
- Freyhult, Lisa, 1977-, et al.
(författare)
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Spiky strings in the SL(2) Bethe Ansatz at strong coupling from AdS/CFT
- 2009
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer Science and Business Media LLC. - 1126-6708 .- 1029-8479. ; :7, s. 038-
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Tidskriftsartikel (refereegranskat)abstract
- We study spiky strings in the context of the SL(2) Bethe ansatz equations. We find an asymmetric distribution of Bethe roots along one cut that determines the all loop anomalous dimension at leading and subleading orders in a large S expansion. At leading order in strong coupling (large lambda) we obtain that the energy of such states is given, in terms of the spin S and the number of spikes n by E-S=n sqrt{lambda}/(2 pi) (ln 16 pi S/(n sqrt{lambda})+ ln sin (pi/n) - 1)+ O(ln S/S). This result matches perfectly the same expansion obtained from the known spiky string classical solution. We then discuss a two cut spiky string Bethe root distribution at one-loop in the SL(2) Bethe ansatz. In this case we find a limit where n goes to infinity, keeping (E+S)/n^2, (E-S)/n, J/n fixed. This is the one loop version of a limit previously considered in the context of the string classical solutions in AdS5 x S5. In that case it was related to a string solution in the AdS pp-wave background.
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| 12. |
- Freyhult, Lisa, 1977-
(författare)
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Students' views on attendance
- 2017
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Ingår i: Transforming patterns through the scholarship of teaching and learning. ; , s. 1-7
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Konferensbidrag (refereegranskat)abstract
- Is the attendance of students important for their results? Are there differences in attendance depending on the type of instruction? What is the reason that students decide not to attend their classes? As a first step in addressing these questions we have considered the view on attendance as expressed by the students.We have analysed over 2500 answers to questions about attendance given by students in physics during five subsequent semesters. The students answered questions about why they chose to attend alternatively not attend, to what degree they attended as well as what would make them attend to a higher extent.The largest groups of answers concern the teaching method, the teacher or different aspects of lack of time. Several of the changes suggested by the students to increase attendance coincide with criteria for research based teaching for effective learning.
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| 13. |
- Freyhult, Lisa, 1977-, et al.
(författare)
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The virtual scaling function of AdS/CFT
- 2009
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Ingår i: Physical Review D. Particles and fields. - : American Physical Society. - 0556-2821 .- 1089-4918. ; 79:10, s. 105009-
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Tidskriftsartikel (refereegranskat)abstract
- We write an integral equation that incorporates finite corrections to the large spin asymptotics of N=4 SYM twist operators from the non-linear integral equation. We show that these corrections are an all-loop result, not affected by wrapping effects, and agree, after determining the strong coupling expansion, with string theory predictions.
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| 14. |
- Freyhult, Lisa, 1977-, et al.
(författare)
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Working with context rich problems to teach problem solving
- 2017
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Ingår i: Transforming patterns through the scholarship of teaching and learning.
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Konferensbidrag (refereegranskat)abstract
- The ability to solve problems is an important ability for scientists as well as engineers and something we identify as a key competence for our students. Problem solving is often examined but still students complain about the difficulty of the examination, describing the problems as more difficult than the problems they have encountered previously.Our study suggests that our students often use inefficient strategies for problem solving, like pattern matching or trying to find a mathematical formula that fits the situation. It is clear that these strategies will not work and they become less and less useful the further the students get in their education.To train problem solving and to prepare students to handle unknown problems and situations cooperative problem solving and context rich problems have been identified as efficient strategies [1,2]. These methods have specifically been used in early courses in mechanics and similar experiences with open ended but shorter problems have been described in [3,4,5]. We have applied these strategies in a more advanced course in Lagrangian mechanics. Students perceive this topic as somewhat abstract and disconnected from everyday experience and lack a clear relevance to their professional role. We describe our work as a team of teachers and our experience introducing a new methodology in the course with the goal to teach in a way that discourages inefficient problem solving strategies.ReferencesHeller, P och Heller, K (2010) Cooperative Problem Solving in Physics A User’s ManualHeller, P, Keith, R och Andersson (1992), Teaching problem solving through cooperative grouping. Part 1: Group versus individual problem solving, S, Am. J. Phys. 60, 627; Heller, P och Hollabaugh, M (1992), Teaching problem solving through cooperative grouping. Part 2: Designing problems and structuring groups, Am. J. Phys. 60, 637Maloney, D., Research on problem solving in physics, in D. Gabel (ed.) (1994), Handbook of research in science teaching and learning, New YorkWedelin, D., Adawi, T., Jahan T. and Andersson, S., (2015), Investigating and developing engineering students’ mathematical modelling and problem-solving skills, European Journal of Engineering Education, 40:5, pp. 557-572Wedelin, D. och Adawi, D. (2015), Warming up for PBL: a course in mathematical modelling and problem solving for engineering students Högre utbildning Vol. 5, No. 1, pp. 23-34
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