Wednesday, January 30, 2019

Some comments about classical conservation laws in Zero Energy Ontology

In Zero Energy Ontology (ZEO), the basic geometric structure is causal diamond (CD), which is a subset of M4× CP2 identified as an intersection of future and past directed light cones of M4 with points replaced with CP2. Poincare symmetries are isometries of M4× CP2 but CD itself breaks Poincare symmetry.

Whether Poincare transformations can act as global symmetries in the "world of classical worlds" (WCW), the space of space-time surfaces - preferred extremals - connecting 3-surfaces at opposite boundaries of CD, is not quite clear since CD itself breaks Poincare symmetry. One can even argue that ZEO is not consistent with Poincare invariance. By holography one can either talk about WCW as pairs of 3-surfaces or about space of preferred extremals connecting the members of the pair.

First some background.

  1. Poincare transformations act symmetries of space-time surfaces representing extremals of the classical variational principle involved, and one can hope that this is true also for preferred extremals. Preferred extremal property is conjectured to be realized as a minimal surface property implied by appropriately generalized holomorphy property meaning that field equations are separately satisfied for Kähler action and volume action except at 2-D string world sheets and their boundaries. Twistor lift of TGD allows to assign also to string world sheets the analog of Kähler action.

  2. String world sheets and their light-like boundaries carry elementary particle quantum numbers identified as conserved Noether charges assigned with second quantized induced spinors solving modified Dirac equation determined by the action principle determining the preferred extremals - this gives rise to super-conformal symmetry for fermions.

  3. The ground states of super-symplectic and super-Kac-Moody representations correspond to spinor harmonics with well-defined Poincare quantum numbers. Excited states are obtained using generators of symplectic algebra and have well-defined four-momenta identifiable also as classical momenta. Quantum classical correspondence (QCC) states that classical charges are equal to the eigenvalues of Poincare generators in the Cartan algebra of Poincare algebra. This would hold quite generally.

  4. In ZEO one assigns opposite total quantum numbers to the boundaries of CD: this codes for the conservation laws. The action of Poincare transformations can be non-trivial at second (active) boundary of CD only and one has two kinds of realizations of Poincare algebra leaving either boundary of CD invariant. Since Poincare symmetries extend to Kac-Moody symmetries analogous to local gauge symmetries, it should be possible to achieve trivial action at the passive boundary of CD so that the Cartan algebra of symmetries act non-trivially only at the active boundary of CD. Physical intuition suggests that Poincare transformations on the entire CD treating it as a rigid body correspond to trivial center of mass quantum numbers.

How do Poincare transformations act on 3-surfaces at the active boundary of CD?
  1. Zero energy states are superpositions of 4-D preferred extremals connecting 3-D surfaces at boundaries of CD, the ends of space-time. One should be able to construct the analogs of plane waves as superpositions of space-time surfaces obtained by translating the active boundary of CD and 3-surfaces at it so that the size of CD increases or decreases. The translate of a preferred extremal is a preferred extremal associated with the new pair of 3-surfaces and has size and thus also shape different from those of the original. Clearly, classical theory becomes an essential part of quantum theory.

  2. Four-momentum eigenstate is an analog of plane wave which is superposition of the translates of a preferred extremal. In practice it is enough to have wave packets so that in given resolution one has a cutoff for the size of translations in various directions. As noticed, QCC requires that the eigenvalues of Cartan algebra generators such as momentum components are equal to the classical charges.

For a summary of earlier postings see Latest progress in TGD.

Articles and other material related to TGD.

Sunday, January 27, 2019

About gauge bosons and their decay vertices in TGD framework

The attempt to understand how unitarity of scattering amplitudes emerges led as side track to a more detailed view about gauge bosons as flux tubes carrying monopole flux and consisting of two long portions with Minkowskian signature and two short portions represented by wormhole contacts. Also a more detailed view about decay vertices emerged.

There question is how elementary particles and their basic interaction vertices could be realized in this framework.

  1. In TGD framework particle would correspond to pair of wormhole contact associated with closed magnetic flux tube carrying monopole flux. Strongly flattened rectangle with Minkowskian flux tubes as long edges with length given by weak scale and Euclidian wormhole contacts as short edges with CP2 radius as lengths scale is a good visualization. 3-particle vertex corresponding to the replication of this kind of flux tube rectangle to two rectangles would replace 3-vertex of Feynman graph. There is analogy with DNA replication. Similar replication is expected to be possible also for the associated closed fermionic strings.

  2. Denote the wormhole contacts by A and B and their opposite throats by Ai and Bi, i=1,2. For fermions A1 can be assumed to carry the electroweak quantum numbers of fermion. For electroweak bosons A1 and A2 (for instance) could carry fermion and anti-fermion, whose quantum numbers sum up to those of ew gauge boson. These "corner fermions" can be called active.

    Also other distributions of quantum numbers must be considered. Fermion and anti-fermion could in principle reside at the same throat - say A1. One can however assume that second wormhole contact, say A has quantum numbers of fermion or weak boson (or gluon) and second contact carries quantum numbers screening weak isospin.

  3. The model assumes that the weak isospin is neutralized in length scales longer than the size of the flux tube structure given by electro-weak scale. The screening fermions can be called passive. If the weak isospin of W+/- boson is neutralized in the scale of flux tube, 2 νLνbarR pairs are needed (lepton number for these pairs must vanish) for W-. For Z νbarLνR and νLνbarR are needed. The pairs of passive fermions could reside in the interior of flux tube, at string world sheet or at its corners just like active fermions. The first extreme is that the neutralizing neutrino-antineutrino pairs reside in interior at the opposite long edges of the rectangular flux tube. Second extreme is that they are at the corners of rectangular closed string.

  4. Rectangular closed string containing active fermion at wormhole A (say) and with members of isospin neutralizing neutrino-antineutrino pair at the throats of B serves as basic units. In scales shorter than string length the end A would behave like fermion with weak isospin. At longer scales physical fermion would be hadron like entity with vanishing isospin and one could speak of confinement of weak isospin.

    From these physical fermions one can build gauge bosons as bound states. Weak bosons and also gluons would be pairs of this kind of fermionic closed strings connecting wormhole contacts A and B. Gauge bosons (and also gravitons) could be seen as composites of string like physical fermions with vanishing net isospin rather than those of point like fundamental fermions.

  5. The decay of weak boson to fermion-antifermion pair would be flux tube replication in which closed strings representing physical fermion and anti-fermion continue along different copies of flux tube structure. The decay of boson to two bosons - say W→ WZ - by replication of flux tube would require creation of a pair of physical fermionic closed strings representing Z. This would correspond to a V-shaped vertex with the edge of V representing closed fermionic closed string turning backwards in time. In decays like Z→ W+W- two closed fermion strings would be created in the replication of flux tube. Rectangular fermionic string would turns backwards in time in the replication vertex and the rectangular strings of Z would be shared between W+ and W-.

This mesonlike picture about weak bosons as bound states of fermions sounds complex as compared with standard model picture. On the other hand only the spinor fields assignable to single fermion family are present. A couple of comments concerning this picture are in order.
  1. M8 duality provides a different perspective. In M8 picture these vertices could correspond to analogs of local 3 particle vertices for octonionic superfield, which become nonlocal in the map taking M8=M4× CP2 surfaces to surfaces in H=M4× CP2. The reason is that M4 point is mapped to M4 point but the tangent space at E4 point is mapped to a point of CP2. If the point in M8 corresponds to a self-intersection point the tangent space at the point is not unique and point is mapped to two distinct points. There local vertex in M8 would correspond to non-local vertex in H and fermion lines could just begin. This would mean that at H-level fermion line at moment of replication and V-shaped fermion line pair beginning at different point of throat could correspond to 3-vertex at M8 level.

  2. The 3-vertex representing replication could have interpretation in terms of quantum criticality: in reversed direction of time two branches of solution of classical field equations would co-incide.

See the article More about the construction of scattering amplitudes in TGD framework or the chapter The Recent View about Twistorialization in TGD Framework.

For a summary of earlier postings see Latest progress in TGD.

Articles and other material related to TGD.

Thursday, January 24, 2019

More about the construction of scattering amplitudes in TGD framework

During years I have considered several proposals for S-matrix in TGD framework - perhaps the most realistic proposal relies on the generalization of twistor Grassmann approach to TGD context. There are several questions waiting for an answer. How to achieve unitarity? What it is to be a particle in classical sense? Can one identify TGD analogs of quantum fields? Could scattering amplitudes have interpretation as Fourier transforms of n-point functions for the analogs of quantum fields?

Unitarity is certainly the issue number 1 and in the sequel almost trivial solution to the unitarity problem based on the existence of super-symplectic transformations acting as isometries of "world of classical worlds" implying infinite number of conserved Noether charges in turn guaranteeing unitarity. Also quantum classical correspondence and the role of string world sheets for strong form of holography are discussed. What is found that number theoretic view justifies the assignment of action to string world sheets.

See the article More about the construction of scattering amplitudes in TGD framework or the chapter The Recent View about Twistorialization in TGD Framework.

For a summary of earlier postings see Latest progress in TGD.

Articles and other material related to TGD.

Sunday, January 20, 2019

About TGD counterparts of classical field configurations in Maxwell's theory

Classical physics is an exact part of TGD so that the study of extremals of dimensionally reduces 6-D Kähler action can provide a lot of intuition about quantum TGD and see how quantum-classical correspondence is realized.
In the following the goal is to develop further understanding about TGD counterparts of the simplest field configurations in Maxwell's theory.

About differences between Maxwell's ED and TGD

TGD differs from Maxwell's theory in several important aspects.

  1. The TGD counterparts of classical electroweak gauge potentials are induced from component of spinor connection of CP2. Classical color gauge potentials corresponds to the projections of Killing vector fields of color isometries.

  2. Also M4 has Kähler potential, which is induced to space-time surface and gives rise to an additional U(1) force. The couplings of M4 gauge potential to quarks and leptons are of same sign whereas the couplings of CP2 Kähler potential to B and L are of opposite sign so that the contributions to 6-D Kähler action reduce to separate terms without interference term.

    Coupling to induced M4 Kähler potential implies CP breaking. This could explain the small CP breaking in hadronic systems and also matter antimatter asymmetry in which there are opposite matter-antimatter asymmetries inside cosmic strings and their exteriors respectively. A priori it is however not obvious that the CP breaking is small.

  3. General coordinate invariance implies that there are only 4 local field like degrees of freedom so that for extremals with 4-D M4 projection corresponding to GRT space-time both metric, electroweak and color gauge potentials can be expressed in terms four CP2 coordinates and their gradients. Preferred extremal property realized as minimal surface condition means that field equations are satisfied separately for the 4-D Kähler and volume action reduces the degrees of freedom further.

    If the CP2 part of Kähler form is non-vanishing, minimal surface conditions can be guaranteed by a generalization of holomorphy realizing quantum criticality (satisfied by known extremals). One can say that there is no dependence on coupling parameters. If CP2 part of Kähler form vanishes identically, the minimal surface condition need not be guaranteed by holomorphy. It is not at all clear whether quantum criticality and preferred extremal property allow this kind of extremals.

  4. Supersymplectic symmetries act as isometries of "world of classical worlds" (WCW). In a well-defined sense supersymplectic symmetry generalizes 2-D conformal invariance to 4-D context. The key observation here is that light-like 3-surfaces are metrically 2-D and therefore allow extended conformal invariance.

    Preferred extremal property realizing quantum criticality boils down to a condition that sub-algebra of SSA and its commutator with SSA annihilate physical states and that corresponding Noether charges vanish. These conditions could be equivalent with minimal surface property. This implies that the set of possible field patterns is extremely restricted and one might talk about "archetypal" field patterns analogous to partial waves or plane waves in Maxwell's theory.

  5. Linear superposition of the archetypal field patterns is not possible. TGD however implies the notion of
    many-sheeted space-time and each sheet can carry its own field pattern. A test particle which is space-time surface itself touches all these sheets and experiences the sum of the effects caused by fields at various sheets. Effects are superposed rather than fields and this is enough. This means weakening of the superposition principle of Maxwell's theory and the linear superposition of fields at same space-time sheet is replaced with set theoretic union of space-time sheets carrying the field patterns whose effects superpose.

    This observation is also essential in the construction of QFT limit of TGD. The gauge potentials in standard model and gravitational field in general relativity are superpositions of those associated with space-time sheets idealized with slightly curved piece of Minkowski space M4.

  6. An important implication is that each system has field identity - field body or magnetic body (MB). In Maxwell's theory superposition of fields coming from different sources leads to a loss of information since one does not anymore now which part of field came from particular source. In TGD this information loss does not happen and this is essential for TGD inspired quantum biology.

    Remark: An interesting algebraic analog is the notion of co-algebra. Co-product is analogous to reversal of product AB= C in the sense that it assigns to C and a linear combination of products ∑ Ai⊗ Bi such that AiBi=C. Quantum groups and co-algebras are indeed important in TGD and it might be that there is a relationship. In TGD inspired quantum biology magnetic body plays a key role as an intentional agent receiving sensory data from biological body and using it as motor instrument.

  7. I have already earlier considered a space-time correlate for second quantization in terms of sheets of covering for heff=nh0. I have proposed that n factorizes as n=n1n2 such that n1 (n2) is the number sheets for space-time surface as covering of CP2 (M4). One could have quantum mechanical linear superposition of space-time sheets, each with a particular field pattern. This kind state would correspond to single particle state created by quantum field in QFT limit. For instance, one could have spherical harmonic for orientations of magnetic flux tube or electric flux tube.

    One could also have superposition of configurations containing several space-time sheets simultaneously as analogs of many-boson states. Many-sheeted space-time would correspond to this kind many-boson states. Second quantization in quantum field theory (QFT) could be seen as an algebraic description of many-sheetedness having no obvious classical correlate in classical QFT.

  8. Flux tubes should be somehow different for gravitational fields, em fields, and also weak and color gauge fields. The value of n=n1n2 for gravitational flux tubes is very large by Nottale formula hbareff= hbargr= GMm/v0. The value of n2 for gravitational flux tubes is n2∼ 107 if one accepts the formula G= R2/n2hbar. For em fields much smaller values of n and therefore of n2 are suggestive. There the value of n measuring in adelic physics algebraic complexity and evolutionary level would distinguish between gravitational and em flux tubes.

    Large value of n would mean quantum coherence in long scales. For gravitation this makes sense since screening is absent unlike for gauge interactions. Note that the large value of heff=hgr implies that αem= e2/4πℏeff is extremely small for gravitational flux tubes so that they would indeed be gravitational in an excellent approximation.

    n would be the dimension of extension of rationals involved and n2 would be the number space-time sheets as covering of M4. If this picture is correct, gravitation would correspond to much larger algebraic complexity and much larger value of Planck constant. This conforms with the intuition that gravitation plays essential role in the quantum physics of living matter.

    There are also other number theoretic characteristics such as ramified primes of the extension identifiable as preferred p-adic primes in turn characterizing elementary particle. Also flux tubes mediating weak and strong interactions should allow characterization in terms of number theoretic parameters. There are arguments that in atomic physics one has h=6h0. Since the quantum coherence scale of hadrons is smaller than atomic scale, one can ask whether one could have heff<h.

In this article CP2 type extremals will be considered from the point of view of quantum criticality and the view about string world sheets, their lightlike boundaries as carriers of fermion number, and the ends as point like particles as singularities acting as sources for minimal surfaces satisfying non-linear generalization of d'Alembert equation.

I will also discuss the delicacies associated with M4 Kähler structure and its connection with what I call Hamilton-Jacobi structure and with M8 approach based on classical number fields. I will argue that the breaking of CP symmetry associated with M4 Kähler structure is small without any additional assumptions: this is in contrast with the earlier view.

The difference between TGD and Maxwell's theory and consider the TGD counterparts of simple em field configurations will be also discussed. Topological field quantization provides a geometric view about formation of atoms as bound states based on flux tubes as correlates for binding, and allows to identify space-time correlates for second quantization. These considerations force to take seriously the possibility that preferred extremals besides being minimal surfaces also possess generalized holomorphy reducing field equations to purely algebraic conditions and that minimal surfaces without this property are not preferred extremals. If so, at microscopic level only CP2 type extremals, massless extremals, and string like objects and their deformations would exist as preferred extremals and serve as building bricks for the counterparts of Maxwellian field configurations and the counterparts of Maxwellian field configurations such as Coulomb potential would emerge only at the QFT limit.

See the article About TGD counterparts of classical field configurations in Maxwell's theory or the chapter About the Identification of the Preferred Kähler Action.

For a summary of earlier postings see Latest progress in TGD.

Articles and other material related to TGD.

Saturday, January 12, 2019

Generalized conformal symmetry, quantum criticality, catastrophe theory, and coupling constant evolution

The notion of quantum criticality allows two realizations: as stationarity of S2 part of the twistor lift of Kähler action and in terms of zeros of zeta are key elements in the explicit proposal for discrete coupling constant evolution reducing to that for cosmological constant.

Quantum criticality from different perspectives

Quantum criticality is however much more general notion, and one must ask how this view relates to the earlier picture.

  1. At the real number side continuous coupling constant evolution makes sense. What does this mean? Can one say that quantum criticality makes possible only adelic physics together with large heff/h0=n as dimension for extension of rationals. This hierarchy is essential for life and cognition.

    Can one conclude that living systems correspond to quantum critical values of S(S2) and therefore αK and in-animate systems correspond to other values of αK? But wouldn't his mean that one gives up the original vision that αK is analogous to critical temperature. The whole point was that this would make physics unique?

    From mathematical view point also continuous αK can make sense. αK can be continuous if it corresponds to a higher-dimensional critical manifold at which two or more preferred extremals associated with the same parameter values co-incide - roots of polynomial P(x,a,b) depending on parameters a,b serves as the canonical example. The degree of quantum criticality would vary and there would be a hierarchy of critical systems characterized by the dimension of the critical manifold. One would have a full analog of statistical physics. For mathematician this is the only convincing interpretation.

    2-D cusp catastrophe serves as a basic example helping to generalize. Cusp corresponds to the roots of dP4/dx=0 of third order polynomial P4(x,a,b), where (a,b) are control variables. The projection of region with 3 real roots to (a,b)-plane is bounded by critical lines forming a roughly V-shaped structure. d2P4/dx2 vanishes at the edges of V, where two roots co-incide and d3P4/dx3 vanishes at the tip of V, where 3 roots co-incide.

  2. A hierarchy of quantum criticalities has been actually assumed. The hierarchy of representations for super-symplectic algebra realizing 4-D analog of super-conformal symmetries allows an infinite hierarchy of representations for which infinite-D sub-algebra isomorphic to a full algebra and its commutator with the full algebra annihilate physical states. Also classical Noether charges vanish. What is new is that conformal weights are non-negative integers. The effective dimensions of these systems are finite - at least in the sense that one one has finite-D Lie algebra (or its quantum counterpart) or corresponding Kac-Moody algebra as symmetries. This realization of quantum criticality generalize the idea that conformal symmetry accompanies 2-D criticality.

    This picture conforms also with the vision about hierarchy of hyper-finite-factors with included hyper-finite factor defining measurement resolution. Hyper-finiteness indeed means finite-dimensionality in excellent approximation.

TGD as catastrophe theory and quantum criticality as prerequisite for the Euclidian signature of WCW metric

It is good to look more precisely how the catastrophe theoretic setting generalizes to TGD.

  1. The value of the twistor lift of Kähler action defining Kähler function very probably corresponds to a maximum of Kähler function since otherwise metric defined by the second derivatives could have non-Euclidian signature. One cannot however exclude the possibility that in complex WCW coordinates the (1,1) restriction of the matrix defined by the second derivatives of Kähler function could be positive definite also for other than minima.

    It would seem that one cannot accept several roots for given zero modes since one cannot have maximum of Kähler function for all of them. This would allow only the the boundary of catastrophe region in which 2 or more roots co-incide. Positive definiteness of WCW metric would force quantum criticality.

    For given values of zero modes there would be single minimum and together with the cancellation of Gaussian and metric determinants this makes perturbation theory extremely simple since exponents of vacuum functional would cancel.

  2. There is an infinite number of zero modes playing the role of control variables since the value of the induce Kähler form is symplectic invariant and there are also other symplectic invariants associated with the M4 degrees of freedom (carrying also the analog of Kähler form for the twistor lift of TGD and giving rise to CP breaking). One would have catastrophe theory with infinite number of control variables so that the number of catastrophes would be infinite so that standard catastrophe theory does not as such apply.

  3. Therefore TGD would not be only a personal professional catastrophe but a catastrophe in much deeper sense. WCW would be a catastrophe surface for the functional gradient of the action defining Kähler function. WCW would consists of regions in which given zero modes would correspond to several minima. The region of zero mode space at which some roots identifiable as space-time surfaces co-incide would be analogous to the V-shaped cusp catastrophe and its higher-D generalizations. The question is whether one allows the entire catastrophe surface or whether one demands quantum criticality in the sense that only the union of singular sets at which roots co-incide is included.

  4. For WCW as catastrophe surface the analog of V in the space of zero modes would correspond to a hierarchy of sub-WCWs consisting of preferred extremals satisfying the gauge conditions associated with a sub-algebra of supersymplectic algebra isomorphic to the full algebra. The sub-WCWs in the hierarchy of sub-WCWs within sub-WCWs would satisfy increasingly stronger gauge conditions and having decreasing dimension just like in the case of ordinary catastrophe. The lower the effective dimension, the higher the quantum criticality.

  5. In ordinary catastrophe theory the effective number of behavior variables for given catastrophe can be reduced to some minimum number. In TGD framework this would correspond to the reduction of super-symplectic algebra to a finite-D Lie algebra or corresponding Kac-Moody (half-)algebra as modes of supersymplectic algebra with generators labelled by non-negative integer n modulo given integer m are eliminated as dynamical degrees of freedom by the gauge conditions: this would effectively leave only the modes smaller than m. The fractal hierarchy of these supersymplectic algebras would correspond to the decomposition of WCW as a catastrophe surface to pieces with varying dimension. The reduction of the effective dimension as two sheets of the catastrophe surface co-incide would mean transformation of some modes contributing to metric to zero modes.

RG invariance implies physical analogy with thermodynamics and gauge theories

One can consider coupling constant evolution and RG invariance from a new perspective based on the minimal surface property.

  1. The critical values of Kähler coupling strength would correspond to quantum criticality of the S2 part S(S2) of 6-D dimensionally reduced Kähler action for fixed values of zero modes. The relative S2 rotation would serve as behavior variable. For its critical values the dimension of the critical manifold would be reduced, and keeping zero modes fixed a critical value of αK would be selected from 1-D continuum.

    Quantum criticality condition might be fundamental since it implies the constancy of the value of the twistor lift of Kähler action for the space-time surfaces contributing to the scattering amplitudes. This would be crucial for number theoretical vision since the continuation of exponential to p-adic sectors is not possible in the generic case. One should however develop stronger arguments to exclude the continuous evolution of Kähler coupling strength in S2 degrees of freedom for the real sector of the theory.

  2. The extremals of twistor lift contain dependence on the rotation parameter for S2 and this must be taken into account in coupling constant evolution along curve of S2 connecting zeros of zeta since Kähler and volume term change with it. This can give an additional non-local term to the evolution equations coming from the dependence of the imbedding space coordinates of the preferred extremal on the evolution parameter. The derivative of the 6-D Kähler action is sum of two terms. The first term involves derivatives of αK and of S(S2). Second term is sum of terms involving derivations of Kähler action and volume with respect to the evolution parameter. This is by chain rule proportional to the functional derivatives of total action with respect to imbedding space coordinates, and vanishes by field equations. It does not matter whether there is coupling between Kähler action and volume term.

Could one find interpretation for the miminal surface property which implies that field equations are separately satisfied for Kähler action and volume term?
  1. Quantum TGD can be seen as a "complex" square root of thermodynamics. In thermodynamics one can define several thermodynamical functions. In particular, one can add to energy E as term pV to get enthalpy H= E+pV, which remains constant when entropy and pressures are kept constant. Could one do the same now?

    In TGD V replaced with volume action and p would be a coupling parameter analogous to pressure. The simplest replacement would give Kähler action as outcome. The replacement would allow RG invariance of the modified action only at critical points so that replacement would be possible only there. Furthermore, field equations must hold true separately for Kähler action and volume term everywhere.

  2. The coupling between Kähler action and volume term could be non-trivial at singular sub-manifolds, where a transfer of conserved quantities between the two degrees of freedom would take place. The transfer would be proportional to the divergence of the canonical momentum current Dα(gαββhk) assignable to the minimal surface and is conserved outside the singular sub-manifolds.

    Minimal surfaces provide a non-linear generalization of massless wave-equation for which the gradient of the field equals to conserved current. Therefore the interpretation could be that these singular manifolds are sources of the analogs of fields defined by M4 and CP2 coordinates.

    In electrodynamics these singular manifolds would represented by charged particles. The simplest interpretation would be in terms of point like charges so that one would have line singularity. The natural identification of world line singularities would be as boundaries of string world sheets at the 3-D light-like partonic orbits between Minkowskian and Euclidian regions having induced 4-metric degenerating to 3-D metric would be a natural identification. These world lines indeed appear in twistor diagrams. Also string world sheets must be assumed and they are are natural candidates for the singular manifolds serving as sources of charges in 4-D context. Induced spinor fields would serve as a representation for these sources. These strings would generalize the notion of point like particle. Particles as 3-surfaces would be connected by flux tubes to a tensor network and string world sheets would connected fermion lines at the partonic 2-surfaces to an analogous network. This would be new from the standard model perspective.

    Singularities could also correspond to a discrete set of points having an interpretation as cognitive representation for the loci of initial and final states fermions at opposite boundaries of CD and at vertices represented topologically by partonic 2-surfaces at which partonic orbits meet. This interpretation makes sense if one interprets the imbedding space coordinates as analogs of propagators having delta singularities at these points. It is quite possible that also these contributions are present: one would have a hierarchy of delta function singularities associated with string worlds sheets, their boundaries and the ends of the boundaries at boundaries of CD, where string world sheet has edges.

  3. There is also an interpretation of singularities suggested by the generalization of conformal invariance. String world sheets would be co-dimension 2 singularites analogous to poles of analytic function of two complex coordinates in 4-D complex space. String world sheets would be co-dimension 2 singularities analogous to poles at light-like 3-surfaces. The ends of the world lines could be analogous of poles of analytic function at partonic 2-surfaces.

    These singularities could provide to evolution equations what might be called matter contribution. This brings in mind evolution equations for n-point functions in QFT. The resolution of the overall singularity would decompose to 2-D, 1-D and 0-D parts just like cusp catastrophe. One can ask whether the singularities might allow interpretation as catastrophes.

  4. The proposal for the analogs of thermodynamical functions suggests the following physical picture. More general thermodynamical functions are possible only at critical points and only if the extremals are miminal surfaces. The singularities should correspond to physical particles, fermions. Suppose that one considers entire scattering amplitude involving action exponential plus possible analog of pV term plus the terms associated with the fermions assigned with the singularities. Suppose that the coupling constant evolution from 6-D Kähler action is calculated without including the contribution of the singularities.

    The derivative of n-particle amplitude with respect to the evolution parameter contains a term coming from the action exponential receiving contributions only from the singularities and a term coming from the operators at singularities. RG invariance of the scattering amplitude would require that the two terms sum up to zero. In the thermodynamical picture the presence of particles in many particle scattering amplitude would force to add the analog of pressure term to the Kähler function: it would be determined by the zero energy state.

    One can of course ask how general terms can be added by requiring minimal surface property. Minimal surface property reduces to holomorphy, and can be true also for other kinds of actions such as the TGD analogs of electroweak and color actions that I considered originally as possible action candidates.

    This would have interpretation as an analog for YM equations in gauge theories. Space-time singularities as local failure of minimal surface property would correspond to sources for H coordinates as analogs of Maxwell's fields and sources currents would correspond to fermions currents.

See the article Does coupling constant evolution reduce to that of cosmological constant?.

For a summary of earlier postings see Latest progress in TGD.

Articles and other material related to TGD.

Monday, January 07, 2019

Cosmological Axis of Evil as a memory from primordial cosmology

Axis of evil is very interesting CMB anomaly (thanks for Sky Darmos for mentioning it in FB discussion). It has been even proposed that it forces Earth-centeredness. According to the Wikipedia article :

"The motion of the solar system, and the orientation of the plane of the ecliptic are aligned with features of the microwave sky, which on conventional thinking are caused by structure at the edge of the observable universe. Specifically, with respect to the ecliptic plane the "top half" of the CMB is slightly cooler than the "bottom half"; furthermore, the quadrupole and octupole axes are only a few degrees apart, and these axes are aligned with the top/bottom divide."

This is indeed really strange looking finding. To my view it does not however bring pre-Keplerian world view back but is related to the possibility of quantum coherence even in cosmological scales predicted by TGD. It would also reflect the situation during very early cosmology, which in TGD framework is cosmic string dominated.

  1. The hierarchy of Planck constants heff=n×h0 implies the existence of space-time sheets with arbitrary large size serving as quantum coherent regions. heff=hgr assignable to flux tubes mediating gravitational interaction the value of heff can be gigantic. hgr= GMm/v 0, where M and m are masses such that M can be solar mass or even larger mass.

  2. Cosmic strings dominated the very early TGD inspired cosmology. They have 2-D projections to M^4 and CP_2 so that GRT is not able to describe them. During the analog of inflationary period the dimension of M^4 projection became D=4 and cosmic strings became magnetic flux tubes. Ordinary GRT space-time emerged and GRT started to be a reasonable approximation as QFT limit of TGD.

  3. Quantum coherence make possible long range correlations. One correlation of this kind could be occurrene of cosmic strings which are nearly parallel in even cosmic scales or more precisely nearly parallel at the time when the TGD counterpart of inflation occurred and the ordinary space-time emerged and cosmic strings thickened to magnetic flux tubes - a process directly corresponding to cosmic expansion. This time corresponds in standard cosmology the end of inflationary period.

    The volume that we observe via CMB now would correspond to a rather small volume at the end of the period when ordinary GRT space-time emerged and it is not too difficult to imagine that in this volume the cosmic strings would have formed a bundle nearly parallel cosmic strings. This property would have been preserved in good approximation during expansion. For instance, angular momentum conservation would have taken care of this if the galaxies along long cosmic strings had angular momenta in parallel: there is indeed evidence for this. Turning of cosmic string to a different direction would require a lot of angular momentum since also the galaxies should be turned at the same time.

  4. Cosmic strings thicknened to flux tubes would contain galaxies - pearls in necklace is good metaphor. Galaxies would be local tangles of flux tubes with topology of dipole type magnetic field in reasonable approximation. Also stars and planets would have formed in the similar manner. This leads to a rather detailed model for galaxy formation. See for instance this.

See the chapter More about TGD and Cosmology or the article Breaking of CP, P, and T in cosmological scales in TGD Universe.

For a summary of earlier postings see Latest progress in TGD.

Articles and other material related to TGD.

Wednesday, January 02, 2019

Solution of renormalization group equation for flux tubes having minimum string tension and RG evolution in terms of Riemann zeta

The great surprise of the last year was that twistor induction allows large number of induced twistor structures. SO(3) acts as moduli space for the dimensional reductions of the 6-D Kähler action defining the twistor space of space-time surface as a 6-D surface in 12-D twistor space assignable to M4× CP2. This 6-D surface has space-time surface as base and sphere S2 as fiber. The area of the twistor sphere in induced twistor structure defines running cosmological constant and one can understand the mysterious smallness of cosmological constant.

This in turn led to the understanding of coupling constant evolution in terms of the flow changing the value of
cosmological constant defined by the area of the twistor sphere of space-time surface for induced twistor structure.

dlog(αK)/ds = -[S(S2)/(SK(X4)+S(S2)] dlog(S(S2))/ds .

Renormalization group equation for flux tubes having minimum string tension

It came as a further pleasant surprise that for a very important special case defined by the minima of the dimensionally reduce action consisting of Kähler magnetic part and volume term one can solve the renormalization group equations explicitly. For magnetic flux tubes for which one has SK(X4)∝ 1/S and Svol∝ S in good approximation, one has SK(X4) =Svol at minimum (say for the flux tubes with radius about 1 mm for the cosmological constant in cosmological scales). One can write

dlog(αK)/ds = -1/2 dlog(S(S2))/ds ,

and solve the equation explicitly:

αK,0K = [S(S2)/S(S2)0]x , x=1/2 .

A more general situation would correspond to a model with x≠ 1/2: the deviation from x=1/2 could be interpreted as anomalous dimension. This allows to deduce numerically a formula for the value spectrum of αK,0K apart from the initial values.

The following considerations strongly suggest that this formula is not quite correct but applies only the real part of Kähler coupling strength. The following argument allows to deduce the imaginary part.

Could the critical values of αK correspond to the zeros of Riemann Zeta?

Number theoretical intuitions strongly suggests that the critical values of 1/αK could somehow correspond to zeros of Riemann Zeta. Riemann zeta is indeed known to be involved with critical systems.

The naivest ad hoc hypothesis is that the values of 1/αK are actually proportional to the non-trivial zeros s=1/2+iy of zeta . A hypothesis more in line with QFT thinking is that they correspond to the imaginary parts of the roots of zeta. In TGD framework however complex values of αK are possible and highly suggestive. In any case, one can test the hypothesis that the values of 1/αK are proportional to the zeros of ζ at critical line. Problems indeed emerge.

  1. The complexity of the zeros and the non-constancy of their phase implies that the RG equation can hold only for the imaginary part of s=1/2+it and therefore only for the imaginary part of the action. This suggests that 1/αK is proportional to y. If 1/αK is complex, RG equation implies that its phase RG invariant since the real and imaginary parts would obey the same RG equation.

  2. The second - and much deeper - problem is that one has no reason for why dlog(αK)/ds should vanish at zeros: one should have dy/ds=0 at zeros but since one can choose instead of parameter s any coordinate as evolution parameter, one can choose s=y so that one has dy/ds=1 and criticality condition cannot hold true. Hence it seems that this proposal is unrealistic although it worked qualitatively at numerical level.

It seems that it is better to proceed in a playful spirit by asking whether one could realize quantum criticality in terms of zeros of zeta.
  1. The very fact that zero of zeta is in question should somehow guarantee quantum criticality. Zeros of ζ define the critical points of the complex analytic function defined by the integral

    X(s0,s)= a∫Cs0→ s ζ (s)ds ,

    where Cs0→ s is any curve connecting zeros of ζ, a is complex valued constant. Here s does not refer to s= sin(ε) introduced above but to complex coordinate s of Riemann sphere.

    By analyticity the integral does not depend on the curve C connecting the initial and final points and the derivative dSc/ds= ζ(s) vanishes at the endpoints if they correspond to zeros of ζ so that would have criticality. The value of the integral for a closed contour containing the pole s=1 of ζ is non-vanishing so that the integral has two values depending on which side of the pole C goes.

  2. The first guess is that one can define Sc as complex analytic function F(X) having interpretation as analytic continuation of the S2 part of action identified as Re(Sc):

    Sc(S2)= F(X(s,s0)) , & X(s,s0)= ∫Cs0→ s ζ (s)ds ,

    S(S2)= Re(Sc)= Re(F(X)) ,

    ζ(s)=0 , & Re(s0)=1/2 .

    Sc(S2)=F(X) would be a complexified version of the Kähler action for S2. s0 must be at critical line but it is not quite clear whether one should require ζ(s0)=0.

    The real valued function S(S2) would be thus extended to an analytic function Sc=F(X) such that the S(S2)=Re(Sc) would depend only on the end points of the integration path Cs0→ s. This is geometrically natural. Different integration paths at Riemann sphere would correspond to paths in the moduli space SO(3), whose action defines paths in S2 and are indeed allowed as most general deformations. Therefore the twistor sphere could be identified Riemann sphere at which Riemann zeta is defined. The critical line and real axis would correspond to particular one parameter sub-groups of SO(3) or to more general one parameter subgroups.

    One would have

    αK,0K= (Sc/S0)1/2 .

    The imaginary part of 1/αK (and in some sense also of the action Sc(S2)) would determined by analyticity somewhat like the real parts of the scattering amplitudes are determined by the discontinuities of their imaginary parts.

  3. What constraints can one pose on F? F must be such that the value range for F(X) is in the value range of S(S2). The lower limit for S(S2) is S(S2)=0 corresponding to J→ 0.

    The upper limit corresponds to the maximum of S(S2). If the one Kähler forms of M4 and S2 have same sign, the maximum is 2× A, where A= 4π is the area of unit sphere. This is however not the physical case.

    If the Kähler forms of M4 and S2 have opposite signs or if one has RP option, the maximum, call it Smax, is smaller. Symmetry considerations strongly suggest that the upper limit corresponds to a rotation of 2π in say (y,z) plane (s=sin(ε)= 1 using the previous notation).

    For s→ s0 the value of Sc approaches zero: this limit must correspond to S(S2)=0 and J→ 0. For Im(s)→ +/- ∞ along the critical line, the behavior of Re(ζ) (see this) strongly suggests that | X|→ ∞ . This requires that F is an analytic function, which approaches to a finite value at the limit |X| → ∞. Perhaps the simplest elementary function satisfying the saturation constraints is

    F(X) = Smaxtanh(-iX) .

    One has tanh(x+iy)→ +/- 1 for y→ +/- ∞ implying F(X)→ +/- Smax at these limits. More explicitly , one has tanh(-i/2-y)= [-1+exp(-4y)-2exp(-2y)(cos(1)-1)]/[1+exp(-4y)-2exp(-2y)(cos(1)-1)]. Since one has tanh(-i/2+0)= 1-1/cos(1)<0 and tanh(-i/2+∞)=1, one must have some finite value y=y0>0 for which one has

    tanh(-i/2+y0)=0 .

    The smallest possible lower bound s0 for the integral defining X would naturally to s0=1/2-iy0 and would be below the real axis.

  4. The interpretation of S(S2) as a positive definite action requires that the sign of S(S2)=Re(F) for a given choice of s0= 1/2+iy0 and for a propertly sign of y-y0 at critical line should remain positive. One should show that the sign of S= a∫ Re(ζ)(s=1/2+it)dt is same for all zeros of ζ. The graph representing the real and imaginary parts of Riemann zeta along critical line s= 1/2+it (see this) shows that both the real and imaginary part oscillate and increase in amplitude. For the first zeros real part stays in good approximation positive but the the amplitude for the negative part increase be gradually. This suggests that S identified as integral of real part oscillates but preserves its sign and gradually increases as required.

A priori there is no reason to exclude the trivial zeros of ζ at s= -2n, n=1,2,....
  1. The natural guess is that the function F(X) is same as for the critical line. The integral defining X would be along real axis and therefore real as also 1/αK provided the sign of Sc is positive: for negative sign for Sc not allowed by the geometric interpretation the square root would give imaginary unit. The graph of the Riemann Zeta at real axis (real) is given in MathWorld Wolfram (see this).

  2. The functional equation

    ζ(1-s)= ζ(s)Γ(s/2)/Γ((1-s)/2)

    allows to deduce information about the behavior of ζ at negative real axis. Γ((1-s)/2) is negative along negative real axis (for Re(s)≤ 1 actually) and poles at n+1/2. Its negative maxima approach to zero for large negative values of Re(s) (see this) whereas ζ(s) approaches value one for large positive values of s (see this). A cautious guess is that the sign of ζ(s) for s≤ 1 remains negative. If the integral defining the area is defined as integral contour directed from s<0 to a point s0 near origin, Sc has positive sign and has a geometric interpretation.

  3. The formula for 1/αK would read as αK,0K(s=-2n) = (Sc/S0)1/2 so that αK would remain real. This integration path could be interpreted as a rotation around z-axis leaving invariant the Kähler form J of S2(X4) and therefore also S=Re(Sc). Im(Sc)=0 indeed holds true. For the non-trivial zeros this is not the case and S=Re(Sc) is not invariant.

  4. One can wonder whether one could distinguish between Minkowskian and Euclidian and regions in the sense that in Minkowskian regions 1/αK correspond to the non-trivial zeros and in Euclidian regions to trivial zeros along negative real axis. The interpretation as different kind of phases might be appropriate.

What is nice that the hypothesis about equivalence of the geometry based and number theoretic approaches can be killed by just calculating the integral S as function of parameter s. The identification of the parameter s appearing in the RG equations is no unique. The identification of the Riemann sphere and twistor sphere could even allow identify the parameter t as imaginary coordinate in complex coordinates in SO(3) rotations around z-axis act as phase multiplication and in which metric has the standard form.

See the article TGD View about Coupling Constant Evolutionor the chapter with the same title.

For a summary of earlier postings see Latest progress in TGD.

Articles and other material related to TGD.

Tuesday, January 01, 2019

Reduction of coupling constant evolution to that for cosmological constant

One of the chronic problems of TGD has been the understanding of what coupling constant evolution could be defined in TGD.

  1. The notion of quantum criticality is certainly central. The continuous coupling constant evolution having no counterpart in the p-adic sectors of adele would contain as a sub-evolution discrete p-adic coupling constant evolution such that the discrete values of coupling constants allowing interpretation also in p-adic number fields are fixed points of coupling constant evolution.

    Quantum criticality is realized also in terms of zero modes, which by definition do not contribute to WCW metric. Zero modes are like control parameters of a potential function in catastrophe theory. Potential function is extremum with respect to behavior variables replaced now by WCW degrees of freedom. The graph for preferred extremals as surface in the space of zero modes is like the surface describing the catastrophe. For given zero modes there are several preferred extremals and the catastrophe corresponds to the regions of zero mode space, where some branches of co-incide. The degeneration of roots of polynomials is a concrete realization for this.

    Quantum criticality would also mean that coupling parameters effectively disappear from field equations. For minimal surfaces (generalization of massless field equation allowing conformal invariance characterizing criticality) this happens since they are separately extremals of Kähler action and of volume term.

    Quantum criticality is accompanied by conformal invariance in the case of 2-D systems and in TGD this symmetry extends to its 4-D analog acting as isometries of WCW.

  2. In the case of 4-D Kähler action the natural hypothesis was that coupling constant evolution should reduce to that of Kähler coupling strength 1/αK inducing the evolution of other coupling parameters. Also in the case of the twistor lift 1/αK could have similar role. One can however ask whether the value of the 6-D Kähler action for the twistor sphere S2(X4) defining cosmological constant could define additional parameter replacing cutoff length scale as the evolution parameter of renormalization group.

  3. The hierarchy of adeles should define a hierarchy of values of coupling strengths so that the discrete coupling constant evolution could reduce to the hierarchy of extensions of rationals and be expressible in terms of parameters characterizing them.

  4. I have also considered number theoretical existence conditions as a possible manner to fix the values of coupling parameters. The condition that the exponent of Kähler function should exist also for the p-adic sectors of the adele is what comes in mind as a constraint but it seems that this condition is quite too strong.

    If the functional integral is given by perturbations around single maximum of Kähler function, the exponent vanishes from the expression for the scattering amplitudes due to the presence of normalization factor. There indeed should exist only single maximum by the Euclidian signature of the WCW Kähler metric for given values of zero modes (several extrema would mean extrema with non-trivial signature) and the parameters fixing the topology of 3-surfaces at the ends of preferred extremal inside CD. This formulation as counterpart also in terms of the analog of micro-canonical ensemble (allowing only states with the same energy) allowing only discrete sum over extremals with the same Kähler action.

  5. I have also considered more or less ad hoc guesses for the evolution of Kähler coupling strength such as reduction of the discrete values of 1/αK to the spectrum of zeros of Riemann zeta or actually of its fermionic counterpart. These proposals are however highly ad hoc.

As I started once again to consider coupling constant evolution I realized that the basic problem has been the lack of explicit formula defining what coupling constant evolution really is.

  1. In quantum field theories (QFTs) the presence of infinities forces the introduction of momentum cutoff. The hypothesis that scattering amplitudes do not depend on momentum cutoff forces the evolution of coupling constants. TGD is not plagued by the divergence problems of QFTs. This is fine but implies that there has been no obvious manner to define what coupling constant evolution as a continuous process making sense in the real sector of adelic physics could mean!

  2. Cosmological constant is usually experienced as a terrible head ache but it could provide the helping hand now. Could the cutoff length scale be replaced with the value of the length scale defined by the cosmological constant defined by the S2 part of 6-D Kähler action? This parameter would depend on the details of the induced twistor structure. It was shown above that if the moduli space for induced twistor structures corresponds to rotations of S2 possibly combined with the reflection, the parameter for coupling constant restricted to that to SO(2) subgroup of SO(3) could be taken to be taken s= sin(ε).

  3. RG invariance would state that the 6-D Kähler action is stationary with respect to variations with respect to s. The variation with respect to s would involve several contributions. Besides the variation of 1/αK(s) and the variation of the S(2) part of 6-D Kähler action defining the cosmological constant, there would be variation coming from the variations of 4-D Kähler action plus 4-D volume term . This variation vanishes by field equations. As matter of fact, the variations of 4-D Kähler action and volume term vanish separately except at discrete set of singular points at which there is energy transfer between these terms. This condition is one manner to state quantum criticality stating that field equations involved no coupling parameters.

    One obtains explicit RG equation for αK and Λ having the standard form involving logarithmic derivatives. The form of the equation would be

    dlog(αK)/ds = -S(S2)/SK(X4)+S(S2) dlog(S(S2))/ds .

    The equation contains the ratio S(S2)/(SK(X4)+S(S2)) of actions as a parameter. This does not conform with idea of micro-locality. One can however argue that this conforms with the generalization of point like particle to 3-D surface. For preferred extremal the action is indeed determined by the 3 surfaces at its ends at the boundaries of CD. This implies that the construction of quantum theory requires the solution of classical theory.

    In particular, the 4-D classical theory is necessary for the construction of scattering amplitudes. and one cannot reduce TGD to string theory although strong form of holography states that the data about quantum states can be assigned with 2-D surfaces. Even more: M8-H correspondence implies that the data determining quantum states can be assigned with discrete set of points defining cognitive representations for given adel This set of points depends on the preferred extremal!

  4. How to identify quantum critical values of αK? At these points one should have dlog(αK)/ds=0. This implies dlog(S(S2)/ds=0, which in turn implies dlog(αK)/ds=0 unless one has SK(X4)+S(S2)=0. This condition would make exponent of 6-D Kähler action trivial and the continuation to the p-adic sectors of adele would be trivial. I have considered also this possibility.

    The critical values of coupling constant evolution would correspond to the critical values of S and therefore of cosmological constant. The basic nuisance of theoretical physics would determine the coupling constant evolution completely! Critical values are in principle possible. Both the numerator J2 and the numerator 1/(det(g))1/2 increase with ε. If the rate for the variation of these quantities with s vary it is possible to have a situation in which the one has

    dlog(J2)/ds =-dlog((det(g))1/2)/ds .

  5. One can test the hypothesis that the values of 1/αK are proportional to the zeros of ζ at critical line. The complexity of the zeros and the non-constancy of their phase implies that the RG equation can hold only for the imaginary part of s=1/2+iy and therefore only for the imaginary part of the action. One can also consider the possibily that 1/αK is proportional to y If the equation holds for entire 1/αK, its phase must be RG invariant since the real and imaginary parts would obey the same RG equation.

  6. One should demonstrate that the critical values of s are such that the continuation to p-adic sectors of the adele makes sense. For preferred extremals cosmological constant appears as a parameter in field equations but does not affect the field equations expect at the singular points. Singular points play the same role as the poles of analytic function or point charges in electrodynamics inducing long range correlations. Therefore the extremals depend on parameter s and the dependence should be such that the continuation to the p-adic sectors is possible.

    A naive guess is that the values of s are rational numbers. Above the proposal s= 2-k/2 motivated by p-adic length scale hypothesis was considered but also s= p-k/2 can be considered. These guesses might be however wrong, the most important point is that there is that one can indeed calculate αK(s) and identify its critical values.

  7. What about scattering amplitudes and evolution of various coupling parameters? If the exponent of action disappears from scattering amplitudes, the continuation of scattering amplitudes is simple. This seems to be the only reasonable option. In the adelic approach amplitudes are determined by data at a discrete set of points of space-time surface (defining what I call cognitive representation) for which the points have M8 coordinates belong to the extension of rationals defining the adele.

    Each point of S2(X4) corresponds to a slightly different X4 so that the singular points depend on the parameter s, which induces dependence of scattering amplitudes on s. Since coupling constants are identified in terms of scattering amplitudes, this induces coupling constant evolution having discrete coupling constant evolution as sub-evolution.

The following argument suggests a connection between p-adic length scale hypothesis and evolution of cosmological constant but must be taken as an ad hoc guess: the above formula is enough to predict the evolution.
  1. p-Adicization is possible only under very special conditions, and suggests that anomalous dimension involving logarithms should vanish for s= 2-k/2 corresponding to preferred p-adic length scales associated with p≈ 2k. Quantum criticality in turn requires that discrete p-adic coupling constant evolution allows the values of coupling parameters, which are fixed points of RG group so that radiative corrections should vanish for them. Also anomalous dimensions Δ k should vanish.

  2. Could one have Δ kn,a=0 for s=2-k/2, perhaps for even values k=2k1? If so, the ratio c/s would satisfy c/s= 2k1-1 at these points and Mersenne primes as values of c/s would be obtained as a special case. Could the preferred p-adic primes correspond to a prime near to but not larger than c/s=2k1-1 as p-adic length scale hypothesis states? This suggest that we are on correct track but the hypothesis could be too strong.

  3. The condition Δ d=0 should correspond to the vanishing of dS/ds. Geometrically this would mean that S(s) curve is above (below) S(s)=xs2 and touches it at points s= x2-k, which would be minima (maxima). Intermediate extrema above or below S=xs2 would be maxima (minima).

See the chapter TGD View about Coupling Constant Evolution or the article with the same title.