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| 2. |
- Terao, Chikashi, et al.
(författare)
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Distinct HLA Associations with Rheumatoid Arthritis Subsets Defined by Serological Subphenotype
- 2019
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Ingår i: American Journal of Human Genetics. - : Cell Press. - 0002-9297 .- 1537-6605. ; 105:3, s. 616-624
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Tidskriftsartikel (refereegranskat)abstract
- Rheumatoid arthritis (RA) is the most common immune-mediated arthritis. Anti-citrullinated peptide antibodies (ACPA) are highly specific to RA and assayed with the commercial CCP2 assay. Genetic drivers of RA within the MHC are different for CCP2-positive and -negative subsets of RA, particularly at HLA-DRB1. However, aspartic acid at amino acid position 9 in HLA-B (Bpos-9) increases risk to both RA subsets. Here we explore how individual serologies associated with RA drive associations within the MHC. To define MHC differences for specific ACPA serologies, we quantified a total of 19 separate ACPAs in RA-affected case subjects from four cohorts (n = 6,805). We found a cluster of tightly co-occurring antibodies (canonical serologies, containing CCP2), along with several independently expressed antibodies (non-canonical serologies). After imputing HLA variants into 6,805 case subjects and 13,467 control subjects, we tested associations between the HLA region and RA subgroups based on the presence of canonical and/or non-canonical serologies. We examined CCP2(+) and CCP2(−) RA-affected case subjects separately. In CCP2(−) RA, we observed that the association between CCP2(−) RA and Bpos-9 was derived from individuals who were positive for non-canonical serologies (omnibus_p = 9.2 × 10−17). Similarly, we observed in CCP2(+) RA that associations between subsets of CCP2(+) RA and Bpos-9 were negatively correlated with the number of positive canonical serologies (p = 0.0096). These findings suggest unique genetic characteristics underlying fine-specific ACPAs, suggesting that RA may be further subdivided beyond simply seropositive and seronegative.
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| 3. |
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| 4. |
- Ananth, S., et al.
(författare)
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A hidden symmetry in quantum gravity
- 2018
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Ingår i: Journal of High Energy Physics. - 1029-8479 .- 1126-6708. ; 2018:11
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Tidskriftsartikel (refereegranskat)abstract
- The action integral contains more information than the equations of motion. Since it is an integral, changes of the integration variables occasionally also expose symmetries more easily than working directly with the equations of motion. We have previously shown that there are signs of an extended exceptional symmetry for N= 8 supergravity in four dimensions. The symmetry is such that the fields used in the Lagrangian are not representations of the symmetry. Instead one has to add representations to obtain a representation of the extended symmetry group. In this paper we discuss an extended symmetry in four-dimensional gravity which is the “Ehlers Symmetry” in three dimensions. It cannot be spanned by the helicity states of four-dimensional gravity but it can be realised once we treat the helicity states just as field variables of the functional integral, which can be changed like variables in any integral. We also explain how this symmetry is inherent in formulations of N= 8 supergravity in four dimensions through a truncation in the field space to pure gravity. The establishment of these “hidden” symmetries should play an important role in the perturbative behaviour of the quantum theories. Since the method used n this paper is purely algebraic we will not provide any information on the geometric role of these symmetries.
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| 5. |
- Ananth, S., et al.
(författare)
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E 8 in N= 8 supergravity in four dimensions
- 2018
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Ingår i: Journal of High Energy Physics. - 1029-8479 .- 1126-6708. ; 2018:1
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Tidskriftsartikel (refereegranskat)abstract
- We argue that N= 8 supergravity in four dimensions exhibits an exceptional E 8(8) symmetry, enhanced from the known E 7(7) invariance. Our procedure to demonstrate this involves dimensional reduction of the N= 8 theory to d = 3, a field redefinition to render the E 8(8) invariance manifest, followed by dimensional oxidation back to d = 4.
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| 6. |
- Ananth, S., et al.
(författare)
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Exceptional versus superPoincaré algebra as the defining symmetry of maximal supergravity
- 2016
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Ingår i: Journal of High Energy Physics. - 1029-8479 .- 1126-6708. ; 2016:3
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Tidskriftsartikel (refereegranskat)abstract
- © 2016, The Author(s). We describe how one may use either the superPoincaré algebra or the exceptional algebra to construct maximal supergravity theories in the light-cone formalism. The d = 4 construction shows both symmetries albeit in a non-linearly realized manner. In d = 11, we find that we have to choose which of these two symmetries to use, in constructing the theory. In order to understand the other “unused” symmetry, one has to perform a highly non-trivial field redefinition. We argue that this shows that one cannot trust counterterm arguments that do not take the full symmetry of the theory into account. Finally we discuss possible consequences for Superstring theory and M-theory.
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| 7. |
- Ananth, S., et al.
(författare)
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Gravitation and quadratic forms
- 2017
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Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479 .- 1126-6708. ; 2017:3
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Tidskriftsartikel (refereegranskat)abstract
- The light-cone Hamiltonians describing both pure (N = 0) Yang-Mills and N = 4 super Yang-Mills may be expressed as quadratic forms. Here, we show that this feature extends to theories of gravity. We demonstrate how the Hamiltonians of both pure gravity and N = 8 supergravity, in four dimensions, may be written as quadratic forms. We examine the effect of residual reparametrizations on the Hamiltonian and the resulting quadratic form.
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| 8. |
- Ananth, Sudarshan, et al.
(författare)
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Maximal supergravity and the quest for finiteness
- 2018
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Ingår i: International Journal of Modern Physics D. - 0218-2718. ; 27:14
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Forskningsöversikt (refereegranskat)abstract
- We show that N = 8 supergravity may possess an even larger symmetry than previously believed. Such an enhanced symmetry is needed to explain why this theory of gravity exhibits ultraviolet behavior reminiscent of the finite N = 4 Yang-Mills theory. We describe a series of three steps that leads us to this result.
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| 9. |
- Ananth, S., et al.
(författare)
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Yang-Mills theories and quadratic forms
- 2015
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Ingår i: Journal of High Energy Physics. - 1029-8479 .- 1126-6708. ; 2015:8
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: We show that the Hamiltonian of (N=1, d = 10) super Yang-Mills can be expressed as a quadratic form in a very similar manner to that of the (N=4, d = 4) theory. We find a similar quadratic form structure for pure Yang-Mills theory but this feature, in the non-supersymmetric case, seems to be unique to four dimensions. We discuss some consequences of this feature. © 2015, The Author(s).
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| 10. |
- Berkovits, Nathan, et al.
(författare)
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Memorial Volume For Stanley Mandelstam
- 2017
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Stanley Mandelstam (1928-2016) was one of the most influential and respected particle theorists. Coming as a young chemical engineer from South Africa to study theoretical physics in England, he quickly became a leading physicist in his field. With his deep understanding of quantum field theory, he pioneered the development of the analytic S-matrix theory as well as the path-dependent formulations for quantum gauge theories and for quantum general relativity. They are being actively used for the electroweak theory and having their imprints in lattice gauge theory and loop quantum gravity. Also he elucidated the mechanisms for quark confinement in quantum chromodynamics, constructed non-perturbative bosonization methods in 1+1 dimensions, and proved the perturbative finiteness and ß=0 of N=4 supersymmetric Yang-Mills theory. His work also led to the discovery of dual resonance models, which in turn became superstring theory. He was a leader in these developments, devoting much of his later years to the proof that the theory is perturbatively finite so it can be considered as a contender for the theory of quantum gravity. He was also a very modest and friendly man, impressing everyone with his sharp intellect as well as his humanity. This volume contains essays written by many of his friends and students, including both detailed reports on his scientific achievements as well as personal reminiscences. Also collected in the volume are some selected reprints of Mandelstam's early seminal papers and abstracts of selected papers representing the full spectrum of his contributions.
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