354 research outputs found
Another Leigh-Strassler deformation through the Matrix model
In here the matrix model approach, by Dijkgraaf and Vafa, is used in order to
obtain the effective superpotential for a certain deformation of N=4 SYM
discovered by Leigh and Strassler. An exact solution to the matrix model
Lagrangian is found and is expressed in terms of elliptic functions.Comment: 15 pages,2 figure
"I see myself": Craving imagery among individuals with addictive disorders.
Craving has been put forward as a core feature of addictive disorders. The present qualitative study investigated the experience of craving among individuals with addictive disorders and recent experiences of cravings. Eleven individuals with Gambling Disorder and ten with Alcohol Use Disorder (nâ=â21) were recruited. A semi-structured interview explored: (1) modes of thought during craving (mental imagery or verbal thoughts), (2) craving content, (3) coping strategies and (4) craving context. The thematic analysis showed that cravings were initially dominated by imagery, with a subsequent conflict between imagery and verbal thoughts. Craving content included imagery of preparative rituals, anticipation, and sensory activation, imagery of the addictive behavior "me, there and then imagery" and anticipating that "something good will come out of it." Some participants related to craving as a symptom of sickness, and coping with craving were through distraction, reminding oneself of negative consequences, or via sensory control: avoiding stimuli associated with the addiction. Craving contexts included typical settings of drinking or gambling and engagement of both positive and negative emotions. Alcohol craving was described as an expected relief from internal stimuli, such as anxiety or stress, whereas gambling craving was more often described as an expectancy of financial reward. Craving was experienced mainly through imagery containing the preparative routines and expected outcomes. Future research and clinical practice should incorporate mode of thought in cravings to better understand its role in the maintenance of the disorders and their treatment
Asymmetric Thermal Lineshape Broadening in a Gapped 3-Dimensional Antiferromagnet - Evidence for Strong Correlations at Finite Temperature
It is widely believed that magnetic excitations become increasingly
incoherent as temperature is raised due to random collisions which limit their
lifetime. This picture is based on spin-wave calculations for gapless magnets
in 2 and 3 dimensions and is observed experimentally as a symmetric Lorentzian
broadening in energy. Here, we investigate a three-dimensional dimer
antiferromagnet and find unexpectedly that the broadening is asymmetric -
indicating that far from thermal decoherence, the excitations behave
collectively like a strongly correlated gas. This result suggests that a
temperature activated coherent state of quasi-particles is not confined to
special cases like the highly dimerized spin-1/2 chain but is found generally
in dimerized antiferromagnets of all dimensionalities and perhaps gapped
magnets in general
Integrable Spin Chains with U(1)^3 symmetry and generalized Lunin-Maldacena backgrounds
We consider the most general three-state spin chain with U(1)^3 symmetry and
nearest neighbour interaction. Our model contains as a special case the spin
chain describing the holomorphic three scalar sector of the three parameter
complex deformation of N=4 SYM, dual to type IIB string theory in the
generalized Lunin-Maldacena backgrounds discovered by Frolov. We formulate the
coordinate space Bethe ansatz, calculate the S-matrix and determine for which
choices of parameters the S-matrix fulfills the Yang-Baxter equations. For
these choices of parameters we furthermore write down the R-matrix. We find in
total four classes of integrable models. In particular, each already known
model of the above type is nothing but one in a family of such models.Comment: 16 pages, 3 figures, references correcte
Quantum Symmetries and Marginal Deformations
We study the symmetries of the N=1 exactly marginal deformations of N=4 Super
Yang-Mills theory. For generic values of the parameters, these deformations are
known to break the SU(3) part of the R-symmetry group down to a discrete
subgroup. However, a closer look from the perspective of quantum groups reveals
that the Lagrangian is in fact invariant under a certain Hopf algebra which is
a non-standard quantum deformation of the algebra of functions on SU(3). Our
discussion is motivated by the desire to better understand why these theories
have significant differences from N=4 SYM regarding the planar integrability
(or rather lack thereof) of the spin chains encoding their spectrum. However,
our construction works at the level of the classical Lagrangian, without
relying on the language of spin chains. Our approach might eventually provide a
better understanding of the finiteness properties of these theories as well as
help in the construction of their AdS/CFT duals.Comment: 1+40 pages. v2: minor clarifications and references added. v3: Added
an appendix, fixed minor typo
The coherent {\it d}-wave superconducting gap in underdoped LaSrCuO as studied by angle-resolved photoemission
We present angle-resolved photoemission spectroscopy (ARPES) data on
moderately underdoped LaSrCuO at temperatures below and
above the superconducting transition temperature. Unlike previous studies of
this material, we observe sharp spectral peaks along the entire underlying
Fermi surface in the superconducting state. These peaks trace out an energy gap
that follows a simple {\it d}-wave form, with a maximum superconducting gap of
14 meV. Our results are consistent with a single gap picture for the cuprates.
Furthermore our data on the even more underdoped sample
LaSrCuO also show sharp spectral peaks, even at the
antinode, with a maximum superconducting gap of 26 meV.Comment: Accepted by Phys. Rev. Let
The general Leigh-Strassler deformation and integrability
The success of the identification of the planar dilatation operator of N=4
SYM with an integrable spin chain Hamiltonian has raised the question if this
also is valid for a deformed theory. Several deformations of SYM have recently
been under investigation in this context. In this work we consider the general
Leigh-Strassler deformation. For the generic case the S-matrix techniques
cannot be used to prove integrability. Instead we use R-matrix techniques to
study integrability. Some new integrable points in the parameter space are
found.Comment: 22 pages, 8 figures, reference adde
The dual string sigma-model of the SU_q(3) sector
In four-dimensional N=4 super Yang-Mills (SYM) the SU(3) sub-sector spanned
by purely holomorphic fields is isomorphic to the corresponding mixed one
spanned by both holomorphic and antiholomorphic fields. This is no longer the
case when one considers the marginally deformed N=4 SYM. The mixed SU(3) sector
marginally deformed by a complex parameter beta, i.e. SU_q(3) with q=e^{2
i\pi\beta}, has been shown to be integrable at one-loop hep-th/0703150, while
it is not the case for the corresponding purely holomorphic one. Moreover, the
marginally deformed N=4 SYM also has a gravity dual constructed by Lunin and
Maldacena in hep-th/0502086. However, the mixed SU_q(3) sector has not been
studied from the supergravity point of view. Hence in this note, for the case
of purely imaginary marginal -deformations, we compute the superstring
SU_q(3) \sigma-model in the fast spinning string limit and show that, for
rational spinning strings, it reproduces the energy computed via Bethe
equations.Comment: 20 page
Field-induced criticality in a gapped quantum magnet with bond disorder
Neutron diffraction and calorimetric measurements are used to study the
field-induced quantum phase transition in
piperazinium-Cu(ClBr) (, x=3.5% and x=7.5%), a
prototypical quantum antiferromagnet with random bonds. The critical indexes
and are determined. The findings contradict some original
predictions for Bose Glass based on the assumption , but are consistent
with recent theoretical results implying . Inelastic neutron experiments
reveal that disorder has a profound effect on the lowest-energy magnetic gap
excitation in the system.Comment: 4.2 pages, 4 figures. Submitted to PRB Rapid Communication
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