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authorkurchan.jorge <kurchan.jorge@gmail.com>2021-03-18 09:58:50 +0000
committeroverleaf <overleaf@localhost>2021-03-18 10:11:23 +0000
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Update on Overleaf.
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@@ -69,7 +69,7 @@ $z\in\mathbb C^N$ and $J$ to be a symmetric tensor whose elements are
$\overline{J^2}=\kappa\overline{|J|^2}$ for complex parameter $|\kappa|<1$. The
constraint remains $z^Tz=N$.
-The motivations for this paper are of two types. On the practical side, there
+The motivations for this paper are of three types. On the practical side, there
are indeed situations in which complex variables appear naturally in disordered
problems: such is the case in which the variables are \emph{phases}, as in
random laser problems \cite{Antenucci_2015_Complex}. Quiver Hamiltonians---used
@@ -80,15 +80,14 @@ plane often uncovers underlying simplicity that is otherwise hidden, shedding
light on the original real problem, e.g., as in the radius of convergence of a
series.
-Deforming an integral in $N$ real variables to a surface of dimension $N$ in
+Finally, deforming an integral in $N$ real variables to a surface of dimension $N$ in
$2N$-dimensional complex space has turned out to be necessary for correctly
defining and analyzing path integrals with complex action (see
\cite{Witten_2010_A, Witten_2011_Analytic}), and as a useful palliative for the
sign problem \cite{Cristoforetti_2012_New, Tanizaki_2017_Gradient,
Scorzato_2016_The}. In order to do this correctly, features of landscape
-of the action in complex space---like the relative position of its
-saddles---must be understood. Such landscapes are in general not random: here
-we propose to follow the strategy of computer science of understanding the
+of the action in complex space--- such as the relative position of saddles and the existence of Stokes lines joining them---must be understood. Such landscapes are in general not random: here
+we propose to follow standard the strategy of computer science of understanding the
generic features of random instances, expecting that this sheds light on
practical, nonrandom problems.
@@ -107,9 +106,7 @@ holomorphic functions without any symmetry. Samples of $H_0$ nearly provide
this, save for a single anomaly: the value of the energy and its gradient at
any point $z$ correlate along the $z$ direction, with $\overline{H_0\partial
H_0}\propto \overline{H_0(\partial H_0)^*}\propto z$. This anomalous direction
-must be neglected, and the constraint surface $z^Tz=N$ is the unique surface
-whose normal is parallel to $z$ and which contains the configuration space of
-the real $p$-spin model as a subspace.
+thus best be forbidden, and the constraint surface $z^Tz=N$ does precisely this.
Second, taking the constraint to be the level set of a holomorphic function
means the resulting configuration space is a \emph{bone fide} complex manifold,
@@ -118,14 +115,13 @@ referenced above. The same cannot be said for the space defined by $z^\dagger
z=N$, which is topologically the $(2N-1)$-sphere and cannot admit a complex
structure.
-A consequence of the constraint is that the model's configuration space is not
-compact, nor is its energy bounded. This is not necessarily problematic, as many
-related problems have similar properties but are concerned with subspaces on
-which the energy is bounded. (In fact, identifying the appropriate subspace
-often requires the study of critical points in the whole space.) Where it might
-become problematic, we introduce an additional constraint that bounds the
-`radius' per spin $r^2\equiv z^\dagger z/N\leq R^2$. The resulting
-configuration space is a complex manifold with boundary. We shall see that the
+Imposing the constraint with a holomorphic function
+makes the resulting configuration space is a \emph{bone fide} complex manifold, which is, as we mentioned, the
+situation we wish to model. The same cannot be said for the space defined by $z^\dagger
+z=N$, which is topologically the $(2N-1)$-sphere, does not admit a complex
+structure, and thus yields a trivial structure of saddles.
+However, we will introduce the domains of
+`radius' per spin $r^2\equiv z^\dagger z/N\leq R^2$, as a device to classify saddles. We shall see that the
`radius' $r$ and its upper bound $R$ prove to be insightful knobs in our present
problem, revealing structure as they are varied. Note that taking $R=1$ reduces
the problem to that of the ordinary $p$-spin.
@@ -159,9 +155,9 @@ usual Kac--Rice formula applied to $\operatorname{Re}H$:
\end{equation}
This expression is to be averaged over $J$ to give the complexity $\Sigma$ as
$N \Sigma= \overline{\log\mathcal N}$, a calculation that involves the replica
-trick. In most of the parameter space that we shall study here, the
+trick. Based on the experience from these problems \cite{Castellani_2005_Spin-glass}, the
\emph{annealed approximation} $N \Sigma \sim \log \overline{ \mathcal N}$ is
-exact.
+expected to be exact wherever the complexity is positive.
The Cauchy--Riemann equations may be used to write \eqref{eq:real.kac-rice} in
a manifestly complex way. With the Wirtinger derivative