scholarly journals Worldline theories with towers of internal states

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Steven Abel ◽  
Daniel Lewis

Abstract We study particle theories that have a tower of worldline internal degrees of freedom. Such a theory can arise when the worldsheet of closed strings is dimensionally reduced to a worldline, in which case the tower is infinite with regularly spaced masses. But our discussion is significantly more general than this, and there is scope to consider all kinds of internal degrees of freedom carried by the propagating particle. For example it is possible to consider towers corresponding to other geometries, or towers with no obvious geometric interpretation that still yield a modular invariant theory. Truncated towers generate non-local particle theories that share with string theory the property of having a Gross-Mende-like saddle point in their amplitudes. This provides a novel framework for constructing exotic theories which may have desirable properties such as finiteness and modular invariance.

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Kunal K. Das ◽  
Miroslav Gajdacz

Abstract Emergence of fundamental forces from gauge symmetry is among our most profound insights about the physical universe. In nature, such symmetries remain hidden in the space of internal degrees of freedom of subatomic particles. Here we propose a way to realize and study gauge structures in real space, manifest in external degrees of freedom of quantum states. We present a model based on a ring-shaped lattice potential, which allows for both Abelian and non-Abelian constructs. Non trivial Wilson loops are shown possible via physical motion of the system. The underlying physics is based on the close analogy of geometric phase with gauge potentials that has been utilized to create synthetic gauge fields with internal states of ultracold atoms. By scaling up to an array with spatially varying parameters, a discrete gauge field can be realized in position space, and its dynamics mapped over macroscopic size and time scales.


Author(s):  
Gregory G. Vilensky

A new theoretical model of ultrasound propagation in soft biological media is presented based on an extended thermodynamics formalism. The long-standing experimental conjecture claiming that a continuous distribution of internal degrees of freedom can be used to model ultrasound in biological media is given theoretical justification. A strategy to derive a well-defined set of equations coupling the balance equations of mass, momentum, energy and entropy with relaxation kinetics of a medium characterized by a continuous distribution of internal states is presented. We demonstrate that new phenomenological coefficients of the proposed governing equations can be extracted directly from experimental data. Our theory successfully explains the anomalous attenuation law found in experiments with biological media that is inconsistent with the conventional models using a finite number of internal degrees of freedom. The results presented offer new possibilities for medical applications of high-intensity ultrasound and ultrasound emission methods to study matter with complex internal structure. These techniques include using pressure relaxation methods for accurate investigation of fast protein folding and a variety of other applications for media where irreversible thermodynamic simulations are essential.


2007 ◽  
Vol 21 (13n14) ◽  
pp. 2362-2370
Author(s):  
J. RANNINGER

We consider systems where the amplitude and the phase of a superfluid order parameter are controlled independently by local, respectively non-local phase correlations of the internal degrees of freedom of quasi-particles which characterize the different phases of such fermionic systems. A possible realization of such a situation is when pairing into the bosonic entities occurs via resonant scattering of itinerant fermionic particles. Examples for that are the ultracold fermionic gases in optical traps and lattices, the correlated electronic systems and strongly coupled electron-phonon systems, such as seen in the high Tc cuprates. We demonstrate the occurrence of a quantum phase transition from a superfluid to a phase uncorrelated boson liquid state in such systems, which is controlled by the competing effects of long and short range phase correlations of the constituents of composite quasi-particles.


Author(s):  
Deep Bhattacharjee

Are aliens transdimensional entities?, By this I have meant to say those beings rather living beings that are existent on different dimensions greater than our 4 that is our normal space-time dimensions. We have enough evidence from the Lorentz generators of the string theory that the maximum space-time dimensions can take the value upto 10, if time is considered as a singular dimension. However, in certain theories like the M-theory where there exists the 11th dimensions as SUGRA or supersymmetric gravity (graviton with gravitino) which on F-theory the dimensional regularization has been taken to 12 by splitting time into 2 dimensions with a higher degrees of freedom. It is very much possible and probable that in a higher dimensions d≫4 time can take the form of 2D where the local nature of 1D time would behave as a singular loop of various multiplicities as a non-local 2D element. In our 4 dimensions also, if we are sustained to believe time being a non-local element with the Einstein’s principle of “spontaneously happening past, present and future then we ought to believe that 1D local time itself acts as a 2D non-local time. Considering the dimensional range of spatial and temporal factor ~ 3+1 it can be said that there are higher ~ 6 additional spatial dimensions which are connected with the lower ~ 3+1 co-dimensions in the form of various inter-dimensional tunnels that specifies the initial and final positions from a lower dimensions to a higher dimensions. Without considering, in this paper, the respective size of the dimensions, if all those space-time dimensions ~ 6+1 are there, then it’s probable that there exists some particular creatures over those various dimensions. However, just as 4D consists of all the 3, 2, 1D’s, similarly the higher order dimensions like 10D would also contains 9, 8, 7, 6, 5…. 1D’s, therefore it can be said that 10D is very unstable and chaotic because of the intersections of various lower co-dimensions that exists in reality. There must be an inter-dimensional membrane that protects one dimensions from the other and those inter-dimensional tunnels, that exists in between (connecting) those dimensions must have an unstable mouth wandering unpredictably from one hyper-surface to another where if anyone gets caught in any of those tunnels mouth’ devoid of any singularities and horizons, then they ought to travel to the other dimensions that will always be >4 as permitted by the laws of physics standing on the 4D universe. Now, analyzing the vehicles that they used to transport from one point in spacetime to other, A detailed analysis on the engineering and phenomenology with respect to mechanisms of the unidentified aerial objects has been carried out extensively on the paper depicting why they are more advanced and on what mechanisms are they capable of the interstellar & intergalactic travel by virtue of electrohydrodynamics and semi-quantum kinetics. KEYWORDS – Hyper-surfaces; Hyper-membranes; Inter-dimensional tunnel, Cauchy horizon, Singularity, Cross-sections, Monodromy, Time slices, Co-dimensions; String theory; Average null energy conditions; f(R,T) gravity.


1989 ◽  
Vol 04 (17) ◽  
pp. 4513-4533 ◽  
Author(s):  
DIETER LÜST ◽  
STEFAN THEISEN

We review the occurrence of exceptional groups in string theory: their dual role as gauge symmetry and as a symmetry unifying space-time, superconformal ghost and internal degrees of freedom. In both cases the relation to the extended world-sheet supersymmetries is discussed in detail. This is used to construct the supermultiplet structure of the massless sectors of all supergravity theories possible in string theory, in even space-time dimensions between four and ten.


2020 ◽  
Author(s):  
Samuel C. Gill ◽  
David Mobley

<div>Sampling multiple binding modes of a ligand in a single molecular dynamics simulation is difficult. A given ligand may have many internal degrees of freedom, along with many different ways it might orient itself a binding site or across several binding sites, all of which might be separated by large energy barriers. We have developed a novel Monte Carlo move called Molecular Darting (MolDarting) to reversibly sample between predefined binding modes of a ligand. Here, we couple this with nonequilibrium candidate Monte Carlo (NCMC) to improve acceptance of moves.</div><div>We apply this technique to a simple dipeptide system, a ligand binding to T4 Lysozyme L99A, and ligand binding to HIV integrase in order to test this new method. We observe significant increases in acceptance compared to uniformly sampling the internal, and rotational/translational degrees of freedom in these systems.</div>


2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
B. Basu-Mallick ◽  
F. Finkel ◽  
A. González-López

Abstract We introduce a new class of open, translationally invariant spin chains with long-range interactions depending on both spin permutation and (polarized) spin reversal operators, which includes the Haldane-Shastry chain as a particular degenerate case. The new class is characterized by the fact that the Hamiltonian is invariant under “twisted” translations, combining an ordinary translation with a spin flip at one end of the chain. It includes a remarkable model with elliptic spin-spin interactions, smoothly interpolating between the XXX Heisenberg model with anti-periodic boundary conditions and a new open chain with sites uniformly spaced on a half-circle and interactions inversely proportional to the square of the distance between the spins. We are able to compute in closed form the partition function of the latter chain, thereby obtaining a complete description of its spectrum in terms of a pair of independent su(1|1) and su(m/2) motifs when the number m of internal degrees of freedom is even. This implies that the even m model is invariant under the direct sum of the Yangians Y (gl(1|1)) and Y (gl(0|m/2)). We also analyze several statistical properties of the new chain’s spectrum. In particular, we show that it is highly degenerate, which strongly suggests the existence of an underlying (twisted) Yangian symmetry also for odd m.


2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Shing Yan Li ◽  
Yu-Cheng Qiu ◽  
S.-H. Henry Tye

Abstract Guided by the naturalness criterion for an exponentially small cosmological constant, we present a string theory motivated 4-dimensional $$ \mathcal{N} $$ N = 1 non-linear supergravity model (or its linear version with a nilpotent superfield) with spontaneous supersymmetry breaking. The model encompasses the minimal supersymmetric standard model, the racetrack Kähler uplift, and the KKLT anti-D3-branes, and use the nilpotent superfield to project out the undesirable interaction terms as well as the unwanted degrees of freedom to end up with the standard model (not the supersymmetric version) of strong and electroweak interactions.


2021 ◽  
pp. 105678952199872
Author(s):  
Bilal Ahmed ◽  
George Z Voyiadjis ◽  
Taehyo Park

In this work, a new damage model for concrete is proposed with an extension of the stress decomposition (limited to biaxial cases), to capture shear damage due to the opposite signed principal stresses. To extract the pure shear stress, the assumption is made that one component of the shear stress is a minimum absolute of the two principal stresses. The opposite signed principal stresses are decomposed into shear stress and uniaxial tensile/compressive stress. A local model is implemented in Abaqus UMAT and it is further extended to a non-local model by utilization of the gradient theory. The concept of three length scales (tension, compression, and shear) is kept the same as the recently proposed nonlocal damage model by the authors. The nonlocal model is implemented in the Abaqus UEL-UMAT subroutine with an eight-node quadrilateral user-defined element, having five degrees of freedom at corner nodes (displacement in X/Y direction and tensile/compressive and shear nonlocal equivalent strain) and two degrees of freedom at internal nodes. Some examples of a local model including uniaxial and biaxial loading are addressed. Also, five examples of mixed crack mode and mode-I cracking are presented to comprehensively show the performance of this model.


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