1,721,064 research outputs found
GHOST COHOMOLOGIES AND HIDDEN SPACE–TIME SYMMETRIES
No full textWe observe and study new nonlinear global space-time symmetries of the full ghost + matter action of RNS superstring theory. We show that these surprising new symmetries are generated by the special worldsheet currents (physical vertex operators) of RNS superstring theory, violating the equivalence of superconformal ghost pictures. We review the questions of BRST-invariance and nontriviality of picture-dependent vertex operators and show their relation to hidden space-time symmetries and hidden space-time dimensions. In particular, we relate the space-time transformations, induced by picture-dependent currents, to the symmetries observed in the 2T physics approach. © World Scientific Publishing Company.Bars I, 1999, PHYS REV D, V59, DOI 10.1103-PhysRevD.59.045019; Bars I, 1999, PHYS REV D, V59, DOI 10.1103-PhysRevD.59.125004; Bars I, 1999, PHYS LETT B, V457, P275, DOI 10.1016-S0370-2693(99)00582-1; KLEBANOV IR, 1991, MOD PHYS LETT A, V6, P3273, DOI 10.1142-S021773239100378X; KLEBANOV IR, 1993, PHYS REV LETT, V71, P3243, DOI 10.1103-PhysRevLett.71.3243; Kogan II, 2003, INT J MOD PHYS A, V18, P1827, DOI 10.1142-S0217751X03013715; LIAN BH, 1991, PHYS LETT B, V254, P417, DOI 10.1016-0370-2693(91)91177-W; Polyakov D, 2005, INT J MOD PHYS A, V20, P2603, DOI 10.1142-S0217751X05020999; Polyakov D, 2002, PHYS REV D, V65, DOI 10.1103-PhysRevD.65.084041; POLYAKOV D, IN PRESS INT J MOD P; Polyakov D, 2005, INT J MOD PHYS A, V20, P4001, DOI 10.1142-S0217751X05024274; VERLINDE E, 1987, PHYS LETT B, V192, P95, DOI 10.1016-0370-2693(87)91148-8; WITTEN E, 1992, NUCL PHYS B, V373, P187, DOI 10.1016-0550-3213(92)90454-J57
GL(1) charged states in twistor string theory
No full textWe discuss the appearance of the GL(1) charged physical operators in the twistor string theory. These operators are shown to be BRST-invariant and non-trivial and some of their correlators and conformal β-functions are computed. Remarkably, the non-conservation of the GL(1) charge in interactions involving these operators, is related to the anomalous term in the Kac-Moody current algebra. While these operators play no role in the maximum helicity violating (MHV) amplitudes, they are shown to contribute non-trivially to the non-MHV correlators in the presence of the worldsheet instantons. We argue that these operators describe the non-perturbative dynamics of solitons in conformal supergravity. The exact form of such solitonic solutions is yet to be determined. © 2005 Published by Elsevier B.V.Azcarraga J., 1989, PHYS REV LETT, V3, P2443; Berkovits N., 2004, JHEP, V0404; Berkovits N., 2004, JHEP, V0408, P009; CACHAZO F, 2004, JHEP, V410; Gubser SS, 1998, PHYS LETT B, V428, P105, DOI 10.1016-S0370-2693(98)00377-3; Maldacena J M, 1998, ADV THEOR MATH PHYS, V2, P231, DOI DOI 10.1023-A:1026654312961; POLYAKOV D, HEPTH0406079; POLYAKOV D, IN PRESS INT J MOD P; Witten E., 1998, ADV THEOR MATH PHYS, V2, P253, DOI DOI 10.1016-S0370-1573(99)00083-6; Witten E., HEPTH9112056; Witten E, 2004, COMMUN MATH PHYS, V252, P189, DOI 10.1007-s00220-004-1187-344
Fluid dynamics of NSR strings
No full textWe show that the renormalization group flows of the massless superstring modes in the presence of fluctuating D-branes satisfy the equations of fluid dynamics. In particular, we show that the D-brane's U(1) field is related to the velocity function in the Navier-Stokes equation while the dilaton plays the role of the passive scalar advected by the turbulent liquid. This leads us to suggest a possible isomorphism between the off-shell superstring theory in the presence of fluctuating D-branes and the fluid mechanical degrees of freedom. © World Scientific Publishing Company.D'Hoker E, 2002, NUCL PHYS B, V636, P3, DOI 10.1016-S0550-3213(02)00431-5; FEIGENBAUM MJ, 1978, J STAT PHYS, V19, P25, DOI 10.1007-BF01020332; FRADKIN ES, 1985, NUCL PHYS B, V261, P1, DOI 10.1016-0550-3213(85)90559-0; FRIEDAN D, 1986, NUCL PHYS B, V271, P93; GAWEDZKI K, 1995, PHYS REV LETT, V75, P3834; Gubser SS, 1998, PHYS LETT B, V428, P105, DOI 10.1016-S0370-2693(98)00377-3; KNIZHNIK VG, 1989, USP FIZ NAUK+, V159, P401, DOI 10.3367-UFNr.0159.198911a.0401; KOBA Z, 1969, NUCL PHYS B, VB 12, P517, DOI 10.1016-0550-3213(69)90071-6; Kogan I, 2003, PHYS ATOM NUCL+, V66, P2062, DOI 10.1134-1.1625749; Kogan II, 2003, INT J MOD PHYS A, V18, P1827, DOI 10.1142-S0217751X03013715; KRAICHNA.RH, 1968, PHYS FLUIDS, V11, P945, DOI 10.1063-1.1692063; KRAICHNAN RH, 1994, PHYS REV LETT, V72, P1016, DOI 10.1103-PhysRevLett.72.1016; Maldacena J M, 1998, ADV THEOR MATH PHYS, V2, P231, DOI DOI 10.1023-A:1026654312961; Polyakov A, 2000, NUCL PHYS B, V581, P116, DOI 10.1016-S0550-3213(00)00183-8; Polyakov AM, 1997, NUCL PHYS B, V486, P23, DOI 10.1016-S0550-3213(96)00601-3; Polyakov D, 2002, PHYS REV D, V65, DOI 10.1103-PhysRevD.65.084041; POLYAKOV D, HEPTH0401009; VERLINDE E, 1987, PHYS LETT B, V192, P95, DOI 10.1016-0370-2693(87)91148-8; Witten E., 1998, ADV THEOR MATH PHYS, V2, P253, DOI DOI 10.1016-S0370-1573(99)00083-644
New superstring isometries and hidden dimensions
No full textWe study the hierarchy of hidden space-time symmetries of noncritical strings in RNS formalism, realized nonlinearly. Under these symmetry transformations the variation of the matter part of the RNS action is canceled by that of the ghost part. These symmetries, referred to as the α-symmetries, are induced by special space-time generators, violating the equivalence of ghost pictures. We classify the α-symmetry generators in terms of superconformal ghost cohomologies Hn ∼ H -n-2(n andgt; 0) and associate these generators with a chain of hidden space-time dimensions, with each ghost cohomology Hn ∼ H -n-2 contributing an extra dimension. Namely, we show that each ghost cohomology Hn ∼ H-n-2 of noncritical superstring theory in d-dimensions contains d + n + 1 α-symmetry generators and the generators from Hk ∼ H-k-2, 1 andlt; k andlt; n, combined together, extend the space-time isometry group from the naive SO(d, 2) to SO(d + n, 2). In the simplest case of n = 1 the α-generators are identified with the extra symmetries of the 2T-physics formalism, also known to originate from a hidden space-time dimension. © World Scientific Publishing Company.Bars I, 1999, PHYS REV D, V59, DOI 10.1103-PhysRevD.59.045019; Bars I, 1999, PHYS REV D, V59, DOI 10.1103-PhysRevD.59.125004; Bars I, 1999, PHYS LETT B, V457, P275, DOI 10.1016-S0370-2693(99)00582-1; Bars I, 1997, PHYS REV D, V55, P2373, DOI 10.1103-PhysRevD.55.2373; KLEBANOV IR, 1991, MOD PHYS LETT A, V6, P3273, DOI 10.1142-S021773239100378X; KLEBANOV IR, 1993, PHYS REV LETT, V71, P3243, DOI 10.1103-PhysRevLett.71.3243; LIAN BH, 1991, PHYS LETT B, V254, P417, DOI 10.1016-0370-2693(91)91177-W; Polyakov D, 2007, INT J MOD PHYS A, V22, P1375, DOI 10.1142-S0217751X07035148; Polyakov D, 2007, INT J MOD PHYS A, V22, P2441, DOI 10.1142-S0217751X07036269; Vafa C, 1996, NUCL PHYS B, V469, P403, DOI 10.1016-0550-3213(96)00172-1; WITTEN E, 1992, NUCL PHYS B, V373, P187, DOI 10.1016-0550-3213(92)90454-J44
CONFORMAL MODULI AND b-c PICTURES FOR NSR STRINGS
No full textWe explore the geometry of superconformal moduli of the NSR superstring theory in order to construct the consistent sigma-model for NSR strings, free of picture-changing complications. The sigma-model generating functional is constructed by the integration over the bosonic and fermionic moduli, corresponding to insertions of the vertex operators in scattering amplitudes. While the integration over the supermoduli leads to the standard picture-changing insertions, the integration over the bosonic moduli results in the appearance of picture-changing operators for the b-c fermionic ghosts with the ghost number -1. Important example of the b-c ghost pictures involves the vertex operators in integrated and unintegrated forms. We obtain the BRST-invariant expressions for the b-c picture-changing operators for open and closed strings and study some of their properties. We also show that the superconformal moduli spaces of the NSR theory contain the global singularities, leading to the phenomenon of ghost-matter mixing and the appearance of nonperturbative D-brane creation operators. © World Scientific Publishing Company.FRADKIN ES, 1985, NUCL PHYS B, V261, P1, DOI 10.1016-0550-3213(85)90559-0; FRIEDAN D, 1986, NUCL PHYS B, V271, P93; Gubser SS, 1998, PHYS LETT B, V428, P105, DOI 10.1016-S0370-2693(98)00377-3; KNIZHNIK VG, 1989, USP FIZ NAUK+, V159, P401, DOI 10.3367-UFNr.0159.198911a.0401; KOBA Z, 1969, NUCL PHYS B, VB 12, P517, DOI 10.1016-0550-3213(69)90071-6; Kogan II, 2003, INT J MOD PHYS A, V18, P1827, DOI 10.1142-S0217751X03013715; Maldacena J M, 1998, ADV THEOR MATH PHYS, V2, P231, DOI DOI 10.1023-A:1026654312961; OHTA N, 1986, PHYS REV D, V33, P1681, DOI 10.1103-PhysRevD.33.1681; OHTA N, 1986, PHYS LETT B, V179, P349; Polchinski J, 1995, PHYS REV LETT, V75, P4724, DOI 10.1103-PhysRevLett.75.4724; Polyakov D, 2002, PHYS REV D, V65, DOI 10.1103-PhysRevD.65.084041; VERLINDE E, 1987, PHYS LETT B, V192, P95, DOI 10.1016-0370-2693(87)91148-8; Witten E., 1998, ADV THEOR MATH PHYS, V2, P253, DOI DOI 10.1016-S0370-1573(99)00083-688
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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