##

scattering theory and number theory

Y. Abe, "Application of abelian holonomy formalism to the elementary theory of numbers" (preprint 06/2010)
[abstract:] "We consider an abelian holonomy operator in two-dimensional conformal field theory with zero-mode contributions. The analysis is made possible by use of a geometric-quantization scheme for abelian Chern-Simons theory on $S^1 \times S^1 \times {\bf R}$. We find that a purely zero-mode part of the holonomy operator can be expressed in terms of Riemann's zeta function. We also show that a generalization of linking numbers can be obtained in terms of the vacuum expectation values of the zero-mode holonomy operators. Inspired by mathematical analogies between linking numbers and Legendre symbols, we then apply these results to a space of ${\bf F}_p = {\bf Z}/ p {\bf Z}$ where $p$ is an odd prime number. This enables us to calculate "scattering amplitudes" of identical odd primes in the holonomy formalism. In this framework, the Riemann hypothesis can be interpreted by means of a physically obvious fact, i.e., there is no notion of "scattering" for a single-particle system. Abelian gauge theories described by the zero-mode holonomy operators will be useful for studies on quantum aspects of topology and number theory."

J.-F. Burnol,
"An adelic causality problem related to abelian
*L*-functions" *J. Number Theory* **87** Série I (2001) 423-428

In this paper, Burnol uses a Lax-Phillips scattering framework to reveal "a natural
formulation of the Riemann Hypothesis, simultaneously for all *L*-functions, as a
property of *causality*."

[excerpts:] "The study of connections between the Riemann zeta function and
scattering theory is at least thirty years old. In particular the Faddeev-Pavlov study of
scattering for automorphic functions [FP] further developed by Lax and Phillips in [LP]
has attracted widespread attention. In their approach the scattering matrix is directly
related to the values taken by the Riemann zeta function on the line Re[*s*] = 1, and the
Riemann Hypothesis itself is equivalent to some decay properties of scattering waves. Another
well-known instance is the approach of De Branges ([DB1], [DB2]) within the theory of Hilbert spaces of entire functions, also related to scattering. Conrey
and Li have recently pointed out some difficulties of this approach:

The connection between our scattering process and the Riemann zeta function...is the
following: each 'bad' zero (Re[*s*] > 1/2) appears as a pole of the scattering operator,
where there should be none, if the process was causal. But if the Riemann Hypothesis holds,
then the scattering itself is of a trivial nature, and says absolutely nothing on the zeros on
the critical line...Our sole motivation in formulating the Riemann Hypothesis in a novel manner
is the hope that creators of other tools, of a deeper nature than those used here, would
incorporate the gained insight in their design constraints."

[FP] L.D Faddeev and B.S. Pavlov, "Scattering theory and automorphic functions", *Seminar of
Steklov Mathematical Institute of Leningrad* **27** (1972) 161-193.

[LP] P. Lax and R.S. Phillips, *Scattering Theory* (1st edition, 1967) revised edition,
*Pure and Applied Mathematics* **26** (Academic Press, 1989)

[DB1] L. De Branges, "The Riemann hypothesis for Hilbert spaces of entire functions", *Bulletin
of the American Mathematical Society* (New Series) **15** no. 1 (1986) 1-17.

[DB2] L. De Branges, "A conjecture which implies the Riemann hypothesis", *Journal of Functional
Analysis* **121** no. 1 (1994) 117-184.

[CL] J.B Conrey and X.-J. Li, "A note on some
positivity conditions related to zeta- and *L*-functions", American Institute of
Mathematics preprint series (1998)

J.-F. Burnol, "Scattering for
time series with an application to the zeta function of an algebraic curve" (preprint, 11/99)

[abstract:] "I explain how the Lax-Phillips theory can be applied to a purely
innovating time series and compute the corresponding scattering function. I then associate
such a time series to an algebraic curve (of genus at least 1) over a finite field and
show that the Riemann Hypothesis (proven long ago) holds if and only if the scattering is
causal (this causality is not independently established, though)."

J.-F. Burnol, "On some bound and scattering states associated with the cosine
kernel" (preprint 01/2008)

[abstract:] "It is explained how to provide self-adjoint operators having scattering states forming a multiplicity one continuum and bound states
whose corresponding eigenvalues have an asymptotic density equivalent to the one of the zeros of the Riemann zeta function. It is shown how this
can be put into an integro-differential form of a type recently considered by Sierra."

J.-F. Burnol,
"Scattering on the *p*-adic field and a trace formula" *Int. Math. Res. Not.*
**2** (2000) 57-70

[abstract] "I apply the set-up of Lax-Phillips Scattering Theory to a non-archimedean local
field. It is possible to choose the outgoing space and the incoming space to be Fourier
transforms of each other. Key elements of the Lax-Phillips theory are seen to make sense and to
have the expected interrelations: the scattering matrix *S*, the projection *K* to the interacting
space, the contraction semi-group *Z* and the time delay operator *T*. The scattering matrix is
causal, its analytic continuation has the expected poles and zeros, and its phase derivative is
the (non-negative) spectral function of *T*, which is also the restriction to the diagonal of the
kernel of *K*. The contraction semi-group *Z* is related to *S* (and *T*) through a trace formula.
Introducing an odd-even grading on the interacting space allows to express the Weil local
explicit formula in terms of a "supertrace". I also apply my methods to the evaluation of a
trace considered by Connes."

J.-F. Burnol, "On Fourier and zeta(*s*)" (habilitation thesis,
submitted to *Forum Mathematicum*)

[abstract] "We study some of the interactions between the Fourier Transform and the Riemann
zeta function (and Dirichlet-Dedekind-Hecke-Tate *L*-functions)."

This involves in-depth discussion of such physics-related topics as scattering, causality,
the Kramers-Wannier duality relation, and the Hilbert-Pólya idea.

[excerpt] "But we do believe that some sort of a much more hidden thing
exists, a Kramers-Wannier like duality exchanging the low temperature
phase with a single hot temperature phase, not number-theoretical. If
this were really the case, some universal properties would hold across
all phases, **reflecting the universality exemplified by the GUE
hypothesis.** Of course the hot phase is then expected to be somehow
related with quantities arising in the study of random matrices. In
the picture from Theorem 7.2, $\Lambda$ seems to play the role of an
inverse temperature (coupling constant).

**We expect that if such a duality did reign on our space it would
interact in such a manner with the renormalization group flow that
this would give birth to scattering processes.** Indeed the duality
could be used to compare incoming to outgoing (classical) states.
**Perhaps the constraints related with this interaction would result in
a property of causality equivalent to the Riemann Hypothesis."**

M.A. Semenov-Tian-Shansky, "Harmonic analysis on Riemannian symmetric spaces of negative
curvature and scattering theory", *Math. USSR Izvestija* **10** (1976) 535-563.

P.D. Lax and R.S. Phillips, "Scattering theory for automorphic functions", *Bulletin
of the American Mathematical Society* **2** (2) (1980) 261- 295.

[abstract:] "This paper is an expository account of our 1976 monograph on *Scattering
theory for automorphic functions*. Several improvements have been incorporated: a more direct proof of the
meromorphic character of the Eisenstein series, an explicit formula for the translation representations and a
simpler derivation of the spectral representations. our hyperbolic approach to the Selberg trace
formula is also included."

M.C. Gutzwiller, "Stochastic
behavior in quantum scattering", *Physica D: Nonlinear Phenomena* **7** (1983)
341-355

[abstract:]
"A 2-dimensional smooth orientable, but not compact space of constant negative curvature with
the topology of a torus is investigated. It contains an open end, i.e. an exceptional point at
infinite distance, through which a particle or a wave can enter or leave, as in the exponential
horn of certain antennas or loud-speakers. In the Poincaré model of hyperbolic geometry, the
solutions of Schrödinger's equation for the reflection of a particle which enters through the
horn are easily constructed. The scattering phase shift as a function of the momentum is
essentially given by the phase angle of Riemann's zeta function on the imaginary axis, at a
distance of from the famous critical line. This phase shift shows all the features of chaos,
namely the ability to mimick any given smooth function, and great difficulty in its effective
numerical computation. A plot shows the close connection with the zeros of Riemann's zeta
function for low values of the momentum (quantum regime) which gets lost only at exceedingly
large momenta (classical regime?) Some generalizations of this approach to chaos are mentioned."

general notes on the number theoretic content of Gutzwiller's
publications involving further remarks on scattering on surfaces of constant negative
curvature, the Selberg Trace Formula, Voronin's
Universality Theorem concerning the Riemann zeta function, *etc.*

D.M. Wardlaw and W. Jaworski, "Time
delay, resonances, Riemann zeros and chaos in a model quantum scattering system",
*Journal of Physics* A **22** (1989) 3561-3575.

[Abstract:] "The quantum treatment of an intrinsically chaotic
model scattering system originally studied by Gutzwiller (1983) is
extended to include the time delay and to make explicit the zeros of
the Riemann zeta function in the mathematical expressions for the
scattering matrix *S* and the time delay. The system consists of a
particle moving on a two-dimensional surface of constant negative
curvature. The scattering in this unusual system is dominated by
resonances associated with poles of *S* in the complex momentum plane,
the real parts of these poles are one-half of the imaginary parts of
the Riemann zeros. The resonances have a constant width but their
average spacing varies with the momentum. The focal point is the
manifestation of chaotic behaviour in the time delay. Features
considered in this regard include: the momentum dependence of the
time delay in regions of overlapping and isolated resonances, the
decomposition of the time delay into an average (dynamical) component
and a fluctuating (chaotic) component, and characterisation of the
fluctuating component by its autocorrelation function."

P.G.O. Freund, "Scattering
on *p*-adic on adelic symmetric spaces", *Physics Letters B* **257** (1991)
119-124

[abstract:] "Explicit S-matrices are constructed for scattering on *p*-adic hyperbolic
planes. Combining these with the known S-matrix on the real hyperbolic plane, an adelic
S-matrix is obtained. It has poles at the nontrivial zeros of the Riemann zeta-function, and is
closely related to scattering on the modular domain of the real hyperbolic plane.
Generalizations of this work and their possible arithmetic relevance are outlined."

J.B Conrey and X.-J. Li, "A note on some
positivity conditions related to zeta- and *L*-functions", American Institute of
Mathematics preprint series (1998)

[abstract:] "In his recent work, Louis de Branges proposed an approach to the generalized Riemann
hypothesis, that is, the hypothesis that not only the Riemann zeta function but also all
the Dirichlet *L*-functions with primitive Dirichlet characters have their nontrivial zeros
lying on the critical line. In a paper, de Branges mentioned that his approach to the
generalized Riemann hypothesis using Hilbert spaces of entire functions is related to the
Lax-Phillips theory of scattering. Peter Lax and Ralph Phillips explained in their book
the difficulty of approaching the Riemann hypothesis by using the scattering theory. In
this note, we shall give examples showing that de Branges' positivity conditions, which
imply the generalized Riemann hypothesis, are not satisfied by defining functions of
reproducing kernel Hilbert spaces associated with the Riemann zeta function and the
Dirichlet *L*-function *L*(*s*;4)."

S.-H. Tang and M. Zworski, "Resonance expansions of scattered waves",
*Commun. Pure Appl. Math.* **53** (2000) 1305-1334

[abstract:] "The purpose of this paper is to describe expansions of solutions
to the wave equation on **R**^{n} with a compactly supported
perturbation present. We show that under a separation condition on resonances,
the solutions can be expanded in terms of resonances close to the real axis,
modulo an error rapidly decaying in time. To avoid the discussion of particular
aspects of potential, gravitational or obstacle scattering, the results are
stated using the abstract 'black box' formalism of Sjöstrand and the second
author."

[excerpt, p.2:] "Two hyperbolic examples: the modular surface and the hyperbolic
cylinder are shown to admit expansion of waves in terms of resonances. However,
even there, the strongest expected version of the expansions is not available as it
would require too much knowledge about the Riemann zeta function (simplicity
and lower bounds on derivatives)..."

P. Lévay, "Chaotic
Aharonov-Bohm scattering on surfaces of constant negative curvature",
*Journal of Physics* A **33** (2000) 4129-4141.

[Abstract:] "A topological model of the Aharonov-Bohm scattering is
presented, where the usual set-up is modelled by a genus-one Riemann
surface with two cusps, *i.e.* leaks infinitely far away. This constant
negative-curvature surface is uniformized by the Hecke congruence
subgroup $\Gamma_{0}(11)$ of the modular group. The fluxes through the holes
are described by the even Dirichlet character for $\Gamma_{0}(11)$. The
scattering matrix having only off-diagonal elements (no reflection) is
calculated. The fluctuating part of the off-diagonal entries shows a
non-trivial dependence on the fluxes as well. The scattering resonances
are related to the non-trivial zeros of a Dirichlet *L*-function. The
chaotic nature of the scattering is related to the distribution of
primes in arithmetical progressions."

P. Lévay, "Chaotic
Aharonov-Bohm scattering on surfaces of constant negative curvature",
*Journal of Physics* A **33** (2000) 4129-4141.

[Abstract:] "A topological model of the Aharonov-Bohm scattering is
presented, where the usual set-up is modelled by a genus-one Riemann
surface with two cusps, *i.e.* leaks infinitely far away. This constant
negative-curvature surface is uniformized by the Hecke congruence
subgroup $\Gamma_{0}(11)$ of the modular group. The fluxes through the holes
are described by the even Dirichlet character for $\Gamma_{0}(11)$. The
scattering matrix having only off-diagonal elements (no reflection) is
calculated. The fluctuating part of the off-diagonal entries shows a
non-trivial dependence on the fluxes as well. The scattering resonances
are related to the non-trivial zeros of a Dirichlet *L*-function. The
chaotic nature of the scattering is related to the distribution of
primes in arithmetical progressions."

M. Pigli, "Adelic
integrable systems" (preprint 07/03)

[abstract:] "Incorporating the zonal spherical function (zsf) problems on
real and *p*-adic hyperbolic planes into a Zakharov-Shabat integrable system
setting, we find a wide class of integrable evolutions which respect the number-theoretic
properties of the zsf problem. This means that at *all* times these real and
*p*-adic systems can be unified into an adelic system with an *S*-matrix which
involves (Dirichlet, Langlands, Shimura...) *L*-functions."

[introduction:] "Scattering theory on real [1] and *p*-adic [2] symmetric spaces can be
unified in an adelic context. This had the virtue of producing *S*-matrices
involving the Riemann zeta function and of throwing new light on earlier work [4]
concerning scattering on the noncompact finite-area fundamental domain of
*SL*(2,**Z**) on the Real hyperbolic plane $H_{\infty}$.

The real hyperbolic plane is a smooth manifold and as such quantum
mechanics on $H_{\infty}$ involves a second order Schrodinger *differential* equation. By contrast the *p*-adic hyperbolic planes *H*_{p} are discrete spaces
(trees), and the corresponding Schrodinger equations are second order *difference* equations. The Jost functions, and therefore the *S*-matrices from all these *local* problems combine in
adelic products, which then involve the Riemann zeta function [2].

At a given time consider all these ("*S*-wave") scattering
problems and then let all of them undergo an *integrable*
time evolution. In general such an evolution need not respect
the number-theoretic endowment of the initial problem. In other words,
even though at the initial time the real and *p*-adic scattering
problems assembled into an interesting adelic scattering problem, at later
times this need no longer be so. We want to explore here the conditions
under which the integrable evolution respects adelizability and to see
what kind of scattering problems can be obtained this way at later times.
Specifically, we will incorporate the initial scattering problem into a
Zakharov-Shabat (ZS) system and follow its integrable evolution. For the
*p*-adic problems, time has to be discrete and for adelic purposes time then has to be discrete in the real problem as well. We will see that
along with the Riemann zeta function involved in the adelic problem at the
initial time, various (Dirichlet, Langlands, Shimura,...)
*L*-functions [5] appear at later times."

[1] M.A. Olshanetsky and A.M. Perelomov, *Phys. Rep.*
**94** (1984) 313; R.F. Wehrhahn, *Rev. Math. Phys.*
**6** (1994) 1339

[2] P.G.O. Freund, *Phys. Lett.* B **257** (1919) 119; L. Brekke and P.G.O. Freund, *Phys. Rep.* **233** (1993) 1

[3] L.O. Chekhov, "*L*-functions
in scattering on *p*-adic multiloop surfaces", *J. Math. Phys.* **36** (1995) 414

[4] L.D. Faddeev and B.S. Pavlov, Sem. LOMI 27 (1972) 161; P.D.
Lax and R.S. Phillips, *Scattering Theory for Automorphic Functions* (Princeton Univ. Press, 1976)

[5] S. Gelbart and F. Shahidi, *Analytic Properties of
Automorphic L-Functions* (Academic, 1988)

S. Joffily, "A model for the quantum vacuum", *Nucl. Phys. A* **790** (1-4) (2007) 631c–634c

[abstract:] "Following our recent works [S. Joffily, Jost function, prime numbers and Riemann zeta function, Contribution to Roberto Salmeron Festschrift, eds. by R. Aldrovandi, et al., AIAFEX, Rio de Janeiro, 2003, math-ph/0303014, S. Joffily, "The Riemann Zeta Function and Vacuum Spectrum", Proceedings of Science, PoS (WC2004) 026, hep-th/0412217] where it was suggested a "potential scattering" Hilbert–Pólya conjecture, such that the nontrivial zeros of Riemann's zeta function could be put in one-to-one correspondence with the zeros of the s-wave Jost function for finite range potentials in the complex momenta plane, we extend our investigation to a relativistic S matrix for a Dirac particle scattering. We then present a description of the vacuum structure as being a dynamical system described by "virtual resonances", completely independent of the second quantization."

S. Joffily, "Jost
function, prime numbers and Riemann zeta function" (preprint 03/2003)

[abstract:] "The large complex zeros of the Jost function (poles of the *S* matrix) in the
complex wave number-plane for *s*-wave scattering by truncated potentials are associated to the
distribution of large prime numbers as well as to the asymptotic behavior of the imaginary
parts of the zeros of the Riemann zeta function on the critical line. A variant of the Hilbert
and Pólya conjecture is proposed and considerations about the Dirac sea as 'virtual resonances'
are briefly discussed."

S. Joffily, "The Riemann zeta function and vacuum
spectrum" (talk presented at the Fourth International Winter Conference on Mathematical Methods in Physics', Rio de Janeiro,
9-13 August 2004)

[abstract:] "A variant for the Hilbert and Pólya spectral interpretation of the Riemann zeta function is proposed. Instead of looking for
a self-adjoint linear operator *H*, whose spectrum coincides with the Riemann zeta zeros, we look for the complex poles of the *S*-matrix that
are mapped into the critical line in coincidence with the nontrivial Riemann zeroes. The associated quantum system, an infinity of "virtual
resonances" described by the corresponding *S*-matrix poles, can be interpreted as the quantum vacuum. The distribution of energy levels
differences associated to these resonances shows the same characteristic features of random matrix theory."

R. Acharya, "Concerning Riemann Hypothesis" (preprint 03/2009)

[abstract:] "We present a quantum mechanical model which establishes the veracity of the Riemann hypothesis that the non-trivial zeros of the Riemann zeta-function lie on the critical line of $\zeta(s)$."

G. Chalmers, "Comment on
the Riemann hypothesis" (preprint 03/05)

[abstract:] "The Riemann hypothesis is identified with zeros of ${\cal N}=4$ supersymmetric gauge
theory four-point amplitude. The zeros of the $\zeta(s)$ function are identified with the
complex dimension of the spacetime, or the dimension of the toroidal compactification. A
sequence of dimensions are identified in order to map the zeros of the amplitude to the
Riemann hypothesis."

A. LeClair, "Interacting Bose and Fermi gases
in low dimensions and the Riemann hypothesis" (preprint, 11/2006)

[abstract:] "We apply the *S*-matrix based finite temperature formalism we recently developed to non-relativistic
Bose and Fermi gases in 1+1 and 2+1 dimensions. In the 2+1 dimensional case, the free energy is given in terms of
Roger's dilogarithm in a way analagous to the relativistic 1+1 dimensional case. The 1-d fermionic case with a
quasi-periodic 2-body potential provides a physical framework for understanding the Riemann hypothesis."

The follow purportedly reduces the Riemann Hypothesis to **an inverse
(quantum) scattering problem**, and (despite the humility of the title), claims to
contain a proof of the RH.

C. Castro, A. Granik, and J. Mahecha,
"On SUSY-QM, fractal
strings and steps towards a proof of the Riemann hypothesis" (preprint 07/01)

[abstract:] "The steps towards a proof of Riemann's conjecture using
spectral analysis are rigorously provided. We prove that the only zeroes
of the Riemann zeta-function are of the form $s = 1/2 + i
\lambda_n$. A supersymmetric quantum mechanical model is proposed
as an alternative way to prove the Riemann conjecture, inspired in the Hilbert-Pólya
proposal; it uses an inverse scattering approach associated witha system of *p*-adic
harmonic oscillators. An interpretation of the Riemann's fundamental relation
*Z*(*s*) = *Z*(1 - *s*) as a duality relation, from one fractal string
*L* to another dual fractal string *L*' is proposed."

C. Castro and J. Mahecha, "A fractal
SUSY-QM model and the Riemann hypothesis" (preprint 06/03)

[abstract:] "The Riemann hypothesis (RH) states that the nontrivial zeros of the
Riemann zeta-function are of the form $s = 1/2 + i\lambda_n$. Hilbert-Pólya
argued that if a Hermitian operator exists whose eigenvalues are the imaginary parts
of the zeta zeros, $\lambda_n$, then the RH is true. In this paper a fractal
supersymmetric quantum mechanical (SUSY-QM) model is proposed to prove the RH. It
is based on a quantum inverse scattering method related to a fractal potential
given by a Weierstrass function (continuous but nowhere differentiable) that is
present in the fractal analog of the CBC (Comtet, Bandrauk, Campbell) formula in
SUSY QM. It requires using suitable fractal derivatives and integrals of irrational
order whose parameter $\beta$ is one-half the fractal dimension of the Weierstrass
function. An ordinary SUSY-QM oscillator is constructed whose eigenvalues are of the
form $\lambda_n = n\pi$, and which coincide with the imaginary parts of the zeros of the
funciton sin(*iz*). This sine function obeys a trivial analog of the RH. A review of our
earlier proof of the RH based on a SUSY QM model whose potential is related ot the
Gauss-Jacobi theta series is also included. The spectrum is given by *s*(1 - *s*)
which is real in the critical line (location of the nontrivial zeros) and in the
real axis (location of the trivial zeros)."

C. Castro and J. Mahecha, "Fractal supersymmetric quantum
mechanics, geometric probability and the Riemann Hypothesis", *International Journal of
Geometric Methods in Modern Physics* **1** no. 6 (2004) 751-793

[abstract:] "The Riemann Hypothesis (RH) states that the nontrivial zeros of the Riemann
zeta-function are of the form $s = 1/2 + i\lambda_{n}$. Earlier work on the RH based on
Supersymmetric QM, whose potential was related to the Gauss-Jacobi theta series, allows to
provide the proper framework to construct the well defined algorithm to compute the probability
to find a zero (an infinity of zeros) in the critical line. Geometric Probability Theory furnishes
the answer to the very difficult question whether the *probability* that the RH is true is
indeed equal to *unity* or not. To test the validity of this Geometric Probabilistic framework
to compute the probability if the RH is true, we apply it directly to the hyperbolic sine function
*sinh*(*s*) case which obeys a trivial analog of the RH. Its zeros are equally spaced
in the imaginary axis $s_n = 0 + in\pi$. The Geometric Probability to find *a* zero (and an
infinity of zeros) in the imaginary axis is exactly *unity*. We proceed with a fractal
supersymmetric quantum mechanical (SUSY-QM) model to implement the Hilbert-Pólya proposal to prove the RH by postulating a Hermitian operator that reproduces all the $\lambda_n$'s
for its spectrum. Quantum inverse scattering methods related to a *fractal* potential
given by a Weierstrass function (continuous but nowhere differentiable) are applied to the
analog of the fractal analog of the CBC (Comtet-Bandrauk-Campbell) formula in SUSY QM. It
requires using suitable fractal derivatives and integrals of irrational order whose parameter
$\beta$ is one-half the fractal dimension (*D* = 1.5) of the Weierstrass function. An
ordinary SUSY-QM oscillator is also constructed whose eigenvalues are of the form
$\lambda_n = n\pi$ and which coincide which the imaginary parts of the zeros of the
function *sinh*(*s*). Finally, we discuss the relationship to
the theory of 1/*f* noise."

C. Castro, "On the Riemann
Hypothesis and tachyons in dual string scattering amplitudes", *International Journal of Geometric Methods in
Modern Physics* **3** no. 2 (2006) 187-199

[abstract:] "It is the purpose of this work to pursue a novel physical interpretation of the nontrivial Riemann
zeta zeros and prove why the location of these zeros $z_n = 1/2+i\lambda_n$ corresponds *physically* to
tachyonic-resonances/tachyonic-condensates, originating from the scattering of two on-shell *tachyons* in bosonic string
theory. Namely, we prove that if there were nontrivial zeta zeros (violating the Riemann hypothesis) outside the critical
line Real $z = 1/2$ (but inside the critical strip), these putative zeros *do not* correspond to any *poles* of
the bosonic open string scattering (Veneziano) amplitude $A(s,t,u)$. The *physical* relevance of
tachyonic-resonances/tachyonic-condensates in bosonic string theory, establishes an important connection between string
theory and the Riemann Hypothesis. In addition, one has also a *geometrical* interpretation of the zeta zeros in the
critical line in terms of very special (degenerate) triangular configurations in the upper-part of the complex plane."

The following appears to be related to the work of Castro, *et. al.*, insofar as it involves inverse scattering:

N.N. Khuri, "Inverse
scattering, the coupling constant spectrum, and the Riemann Hypothesis", *Math. Phys. Anal. Geom.*
**5** (2002) 1-63

"We use inverse scattering methods, generalized for a specific class of complex
potentials, to construct a one parameter family of complex potentials
*V*(*s*,*r*) which have the property that the zero energy *s*-wave Jost
function, as a function of *s* alone, is identical to Riemann's $\xi$ function whose zeros are the non-trivial zeros of the zeta function. These potentials have an asymptotic expansion in inverse powers of *s*(*s*-1) with real coefficients *V*_{n}(*r*) which are
explicitly calculated. We show that the validity of the Riemann hypothesis depends essentially on simple integrability properties of the first order coefficient, *V*_{1}(*r*). In the case studied in this
paper, this coefficient does not satisfy these conditions, but proof of that fact does indicate several possibilities for proceeding further."

A. Wirzba, Zeta
functions in scattering problems evaluated on the real wave number axis"

[abstract:] "Using the two-dimensional 3-disk system (in the A_{1} representation)
we compare the cluster phase shifts of the exact quantum mechanical problem with the corresponding
cluster phase shift of the following semi-classical zeta functions: (a) the Gutzwiller-Voros
zeta function, (b) the dynamical zeta function and (c) the quasi-classical determinant. Furthermore
we show results for the squared moduli of the quantum mechanical and semi-classical determinants on
the real wave number axis. As the cluster phase shifts are in principle measurable quantities,
even experimentalists can now decide which of the three choices is the best."

S.C. Woon, "Analytic
continuation of Bernoulli numbers, a new formula for the Riemann zeta
function, and the phenomenon of scattering of zeros" (preprint 05/97)

"The new concept of dynamics of the zeros of analytic continued
polynomials is introduced, and an interesting phenomenon of 'scatterings'
of the zeros of [the Bernoulli polynomials] B_{s}(z) is
observed"

Animations of the above phenomenon can be viewed
here

R.K. Bhaduri, Avinash Khare,
and J. Law,
"Phase of the Riemann zeta function and the inverted harmonic oscillator",
*Physical Review E* **52** no. 1 (1995) 486-491

[abstract] The Argand diagram is used to display some
characteristics of the characteristics of the Riemann zeta function. The
zeros of the zeta function on the complex plane give rise to an infinite
sequence of closed loops, all passing through the origin of the diagram.
The behaviour of the phase of he zeta function on and off the line of zeros
is studied. Up to some distance from the line of the complex zeros, the
phase angle is shown to still retain their memory. The Argand plots also
lead to an analogy with the scattering amplitude and an approximate rule
for the location of the zeros. The smooth phase of the zeta function along
the line of the zeros is related to the quantum density of states of an
inverted oscillator.

"The loop structure of the zeta function ...with some near-circular
shapes, is reminiscent of the Argand plots for the scattering amplitudes
of different partial waves in the analysis of resonances, for example,
in pion-nucleon scattering."

R.K. Bhaduri, Avinash Khare,
S.M. Reimann, and
E.L. Tomusiak, "The Riemann zeta function and the inverted harmonic
oscillator", *Annals of Physics* **254** no. 1 (1997)

[abstract] The Riemann zeta function has phase jumps of $\pi$ every time it
changes sign as the parameter *t* in the complex argument *s* =
1/2 + *it* is varied. We show analytically that as the real part of
the argument is increased to $\rho$ > 1/2, the memory of the zeros
fades only gradually through a Lorentzian smoothing of the density of
the zeros. The corresponding trace formula, for $\rho$ >> 1,
is of the same form as that generated by a one-dimensional harmonic
oscillator in one direction, along with an inverted oscillator in
the transverse direction. It is pointed out that Lorentzian
smoothing of the level density for more general dynamical systems
may be done similarly. The Gutzwiller trace formula for the simple
saddle plus oscillator model is obtained analytically, and is
found to agree with the quantum result

[Introduction]

The Riemann zeta function *zeta*(*s*) of the complex variable *s* =
$\rho$ + *it* has an infinite number of zeros on the half-line $\rho$ = 1/2
[1]. Along this line, as a function of *t*, every time that $\zeta>(s)$ changes
sing a discontinuous jump by $\pi$ in the phase angle is introduced. Otherwise the phase
angle is a smooth function of *t*. In a previous paper [2], it was noted that as
$\rho$ is increased, the phase of the zeta function is smoothed gradually, and the smooth
part is directly linked to the quantum scattering phase shift of a one-dimensional inverted
harmonic oscillator. In this paper, we first examine the phase of $\zeta(s)$ and
show that its derivative with respect to *t* for a fixed $\rho$ > 1/2 is the
Lorentz-smoothed oscillating part of the density of the zeros at $\rho = 1/2$. The latter
may also be expressed [3] as a Gutzwiller-like trace formula with primitive orbits whose periods
are the logarithms of the prime numbers. By choosing $\rho$ >> 1, the contributions of
the larger primes are severely damped. In this limit of large damping, the residual oscillating
part of the density of states appears to be of the form of a harmonic oscillator, but with a
denominator corresponding to an unstable periodic orbit. In the present paper, we show that this
instability in a periodic orbit may be brought about by a very simple model Hamiltonian. In
particular, we examine the motion of a particle in a plane, bounded by a harmonic oscillator
potential alnong one axis and by a parabolic saddle in the transverse direction. This dynamical
model is a caricature of the Riemann zeta function for very large $\rho$. Interestingly
enough, the electrostatic potential at the bottleneck of a quantum point contact in a mesoscopic
structure [4] has the same shape. In this constriction of the split-gate system, the electron
transmission through the saddle may take place in quantised channels, corresponding to the bound
states of the one-dimensional harmonic potential. This gives rise to quantised conductance steps
that are seen experimentally. The relevance of this will be discussed later. The focus in this
paper, however, is not the well-studied transmission problem through this potential, but the
semiclassical density of states and its asymptotic connection to the Riemann zeta function. The
classical motion perpendicular to the saddle has only one isolated (unstable) periodic orbit
and its repetitions. The semiclassical trace formula using the Gutzwiller approach [5] and the
Selberg zeta function [6] of this system are obtained analytically. The corresponding
bound-state problem of the two- (and higher) dimensional harmonic oscillator has been recently
solved by the same method [7]. In our example, the role of the inverted oscillator is to damp
out the higher harmonics and improve the convergence of the Selberg zeta function. The quantum
mechanical density of states is also obtained analytically. A detailed comparison of the
semclassical and quantum results shows that the semiclassical trace formula accurately
reproduces the quantum result.

Obviously, this toy model is not the dynamic Hamiltonian that describes the phase of
$\zeta(s)$ even outside the strip $\rho$ > 1. But asymptotically, for very
large $\rho$, when all but the lowest prime (=2) is dominant, the saddle-like planar
potential appears to have relevance. In particular, the curvature of the inverted potential at
the saddle is found to be directly proportional to the parameter rho of the zeta function.
Recalling that the phase of $\zeta(s)$ on the $\rho$ = 1 line is described by
the quantum scattering phase shift of a non-Euclidean surface of constant negative curvature
[8], the current work poses the question of whether a single Hamiltonian may describe the phase
of $\zeta(s)$ for the entire range $\rho$ >> 1.

Y. Petridis, "Zeros
of the Riemann zeta function and central values of *L*-series of holomorphic cusp forms"

"We examine the stability of the zeros of the Riemann zeta function,
which are twice the scattering poles of SL(2,**Z**), in relation to
the central value of the *L*-series of holomorphic cusp forms of weight
2 for the congruence subgroups $\Gamma_0(q)$, *q* prime. We work with perturbations in characters varieties of $\Gamma_0(q)$ and study the
effects on the spectral and scattering theory of the Laplace operator.

Y. Petridis , "Perturbation of scattering poles for hyperbolic surfaces and central
values of *L*-series", *Duke Math. J.* **103** no. 1 (2000) 101-130
[DVI file]

R. Delbourgo and A. Ritz, "The effective
Lagrangian for low energy photon interactions in any dimension" (preprint 03/95)

"The subject of low energy photon-photon scattering is considered in arbitrary dimensional
space-time and the interaction is widened to include scattering events involving an arbitrary
number of photons. The effective interaction Lagrangian for these processes in QED has been
determined in a manifestly invariant form. This generalisation resolves the structure of the
weak-field Euler-Heisenberg Lagrangian and indicates that the component invariant functions have
coefficients related, not only to the space-time dimension, but also to the generalised
Riemann-Zeta function."

Erik Balslev,
"Spectral theory of
Laplace operators on hyperbolic Riemann surfaces"

(a course given at the University of Aarhus - in which poles of certain scattering
matrices are related to the Riemann zeta zeros)

A. Knauf, "Irregular scattering, number theory, and statistical mechanics" , from
*Stochasticity and Quantum Chaos* (eds. Z. Haba, *et. al.*) Dordrecht (Kluwer,1995)

Xian-Shun Luo, "Riemann Hypothesis and Levison
Theorem" (preprint 12/2008)

[abstract:] "In this paper we will give a simple proof of Riemann Hypothesis, considered to be one of the greatest unsolved problem in mathematics,
related to inverse scattering problem and radom matrices. The important relationship between Riemann Hypothesis and random matrices was found by Freeman J.
Dyson (1972). Dyson [wrote] a paper [in] 1975 [which] related random matrices and inverse scattering problem. Under this explanation, the famous Riemann
Hypothesis is equivalent to Levison theorem of scattering phase-shifts. We will prove this relation."