Drastic suppression of superconducting $T_{c}$ by anisotropic strain near a nematic quantum critical point

**phases**. In the iron-based superconductor $Ba(Fe_{1-x}Co_{x})_{2}As_{2}$, the superconducting state shares the composition-temperature

**phase**diagram with an electronic nematic

**phase**and an antiferromagnetic

**phase**that break the crystalline rotational symmetry. Symmetry considerations suggest that anisotropic strain can enhance these competing

**phases**and thus suppress the superconductivity. Here we study the effect of anisotropic strain on the superconducting

**transition**in single crystals of $Ba(Fe_{1-x}Co_{x})_{2}As_{2}$ through electrical transport, magnetic susceptibility, and x-ray diffraction measurements. We find that in the underdoped and near-optimally doped regions of the

**phase**diagram, the superconducting critical temperature is rapidly suppressed by both compressive and tensile stress, and in the underdoped case this suppression is enough to induce a strain-tuned superconductor to metal quantum

**phase**

**transition**.

5/10 relevant

arXiv

**Phase** **transitions** for degenerate random environments

**phase**

**transition**for the geometry of connected clusters as $p$ varies.

8/10 relevant

arXiv

Quasiperiodic dynamical quantum **phase** **transitions** in multiband
topological insulators and connections with entanglement entropy and fidelity
susceptibility

**phase**

**transitions**, and find a simple scaling law as a function of the number of bands of our multiband model which is found to be the same for both bulk and boundary fidelity susceptibilities. Expand abstract.

**phase**

**transitions**in multiband one dimensional topological insulators. For this purpose we introduce a new solvable multiband model based on the Su-Schrieffer-Heeger model, generalized to unit cells containing many atoms but with the same symmetry properties. Such models have a richer structure of dynamical quantum

**phase**

**transitions**than the simple two-band topological insulator models typically considered previously, with both quasiperiodic and aperiodic dynamical quantum

**phase**

**transitions**present. Moreover the aperiodic

**transitions**can still occur for quenches within a single topological

**phase**. We also investigate the boundary contributions from the presence of the topologically protected edge states of this model. Plateaus in the boundary return rate are related to the topology of the time evolving Hamiltonian, and hence to a dynamical bulk-boundary correspondence. We go on to consider the dynamics of the entanglement entropy generated after a quench, and its potential relation to the critical times of the dynamical quantum

**phase**

**transitions**. Finally, we investigate the fidelity susceptibility as an indicator of the topological

**phase**transitions, and find a simple scaling law as a function of the number of bands of our multiband model which is found to be the same for both bulk and boundary fidelity susceptibilities.

9/10 relevant

arXiv

Continuous quantum **phase** **transition** in the fermionic mass solutions of
the Nambu-Jona-Lasinio model

**phase**structure of the model. This intriguing fact leads us to investigate whether similar Hamiltonians with four-point interactions can also be studied as a function of their four-point coupling strength. In this paper, we reexamine the Nambu-Jona-Lasinio model, regarding it generally beyond the context of quantum chromodynamics. Essentially, it is a model in which particle-antiparticle pairing leads to a BCS-like condensate, with the result that chiral symmetry is broken dynamically in the strong-coupling regime. To study the behavior of the system, it is necessary to move from this regime to a hypothetical regime of weak coupling, altering the coupling strength of the interaction arbitrarily. In order to do this, the gap equation must be regarded as complex and its Riemann surface structure must be known. We do this and obtain a continuous quantum

**phase**

**transition**characterized by the development of a complex order parameter (the dynamically generated mass) from the second sheet of the Riemann surface, as we move into the weak-coupling regime. The power-law behavior of the order parameter in the vicinity of the

**phase**

**transition**point is demonstrated to be independent of the choice of the regularization scheme with the critical exponent as $\beta \approx 0.55$. At the same time, the isovector pseudoscalar modes retain their feature as Goldstone modes and still have zero mass, while the isoscalar scalar meson follows the behavior of the order parameter and gains a width. Energetically, this mode is not favored over the normal, uncondensed mode but would have to be accessed through an excitation process.

10/10 relevant

arXiv

**Phase** **transitions** for chase-escape models on Gilbert graphs

**phase**

**transitions**of local and global survival in a two-species model on Gilbert graphs. Expand abstract.

**phase**

**transitions**of local and global survival in a two-species model on Gilbert graphs. At initial time there is an infection at the origin that propagates on the Gilbert graph according to a continuous-time nearest-neighbor interacting particle system. The Gilbert graph consists of susceptible nodes and nodes of a second type, which we call white knights. The infection can spread on susceptible nodes without restriction. If the infection reaches a white knight, this white knight starts to spread on the set of infected nodes according to the same mechanism, with a potentially different rate, giving rise to a competition of chase and escape. We show well-definedness of the model, isolate regimes of global survival and extinction of the infection and present estimates on local survival. The proofs rest on comparisons to the process on trees, percolation arguments and finite-degree approximations of the underlying random graphs.

7/10 relevant

arXiv

Metal-Insulator and Magnetic **Phase** Diagram of Ca$_2$RuO$_4$ from
Auxiliary Field Quantum Monte Carlo and Dynamical Mean Field Theory

**phase**

**transitions**easily tuned by temperature, pressure, epitaxy, and nonlinear drive. In this work, we combine results from two complementary state of the art many-body methods, Auxiliary Field Quantum Monte Carlo and Dynamical Mean Field Theory, to determine the low-temperature

**phase**diagram of Ca$_2$RuO$_4$. Both methods predict a low temperature, pressure-driven metal-insulator

**transition**accompanied by a ferromagnetic-antiferromagnetic

**transition**. The properties of the ferromagnetic state vary non-monotonically with pressure and are dominated by the ruthenium $d_{xy}$ orbital, while the properties of the antiferromagnetic state are dominated by the $d_{xz}$ and $d_{yz}$ orbitals. Differences of detail in the predictions of the two methods are analyzed. This work is theoretically important as it presents the first application of the Auxiliary Field Quantum Monte Carlo method to an orbitally-degenerate system with both Mott and Hunds physics, and provides an important comparison of the Dynamical Mean Field and Auxiliary Field Quantum Monte Carlo methods.

4/10 relevant

arXiv

Does one-step replica symmetry breaking occur in p-spin Ising models outside mean-field theory?

**phase**

**transition**from the paramagnetic

**phase**to a stable state with one-step replica symmetry breaking (1RSB). However, simulations in three dimension do not look like these mean-field results and have features more like those which would arise with full replica symmetry breaking (FRSB). To help understand how this might come about we have studied in the fully connected $p$-spin model the state of two-step replica symmetry breaking (2RSB). It has a free energy degenerate with that of 1RSB, but the weight of the additional peak in $P(q)$ vanishes. We expect that the state with full replica symmetry breaking (FRSB) is also degenerate with that of 1RSB. We suggest that finite size effects will give a non-vanishing weight to the FRSB features, as also will fluctuations about the mean-field solution. Our conclusion is that outside the fully connected model in the thermodynamic limit, FRSB is to be expected rather than 1RSB.

4/10 relevant

arXiv

**Transition** region loops in the very late **phase** of flux-emergence in IRIS
sit-and-stare observations

**transition**region loops taken by the Interface Region Imaging Spectrograph (IRIS) at Si IV 1394 \AA\ with a sit-and-stare mode. The loops are corresponding to the flux emergence at its very late

**phase**when the emerged magentic features in the photosphere have fully developed. We find the

**transition**region loops are still expanding and moving upward with a velocity of a few kilometers per second ($\lesssim$10 km/s) at this stage. The expansion of the loops leads to interactions between themselves and the ambient field, which can drive magnetic reconnection evidenced by multiple intense brightenings, including

**transition**region explosive events and IRIS bombs in the footpoint region associated with the moving polarity. A set of quasi-periodic brightenings with a period of about 130 s is found at the loop apex, from which the Si IV 1394 \AA\ profiles are significantly non-Gaussian with enhancements at both blue and red wings at Doppler velocities of about 50 km/s. We suggest that the

**transition**region loops in the very late

**phase**of flux emergence can be powered by heating events generated by the interactions between the expanding loops and the ambient fields and also by (quasi-)periodic processes, such as oscillation-modulated braiding reconnection.

4/10 relevant

arXiv

Gravitational Waves from **Phase** **Transition** in Minimal SUSY $U(1)_{B-L}$
Model

**phase**

**transition**occurs at nucleation temperature of $O(100)$-$O(1000)$~TeV, it can generate stochastic gravitational waves in $O(10)$-$O(100)$ Hz range if $\beta_{\rm n}/H_{\rm n}=1000$, which can be detected by ground-based detectors. Meanwhile, supersymmetry (SUSY) may play a crucial role in the dynamics of such high-scale $U(1)$ gauge symmetry breaking, because SUSY breaking scale is expected to be at TeV to solve the hierarchy problem. In this paper, we study the

**phase**

**transition**of $U(1)$ gauge symmetry breaking in a SUSY model in the SUSY limit. We consider a particular example, the minimal SUSY $U(1)_{B-L}$ model. We derive the finite temperature effective potential of the model in the SUSY limit, study a $U(1)_{B-L}$-breaking

**phase**transition, and estimate gravitational waves generated from it.

10/10 relevant

arXiv

Magnetic Polymer Models for Epigenetics-Driven Chromosome Folding

**phases**which qualitatively agrees with observations in vivo. Expand abstract.

**phase**

**transition**underlies the simultaneous spreading of certain epigenetic marks and the conformational collapse of a chromosome. Further, we describe Brownian Dynamics simulations of the model in which the topology of the polymer and thermal fluctuations are fully taken into account and that confirm our mean field predictions. Extending our models to allow for non-equilibrium terms yields new stable

**phases**which qualitatively agrees with observations in vivo. Our results show that statistical mechanics techniques applied to models of magnetic polymers can be successfully exploited to rationalize the outcomes of experiments designed to probe the interplay between a dynamic epigenetic landscape and chromatin organization.

4/10 relevant

bioRxiv