arXiv subjects

A. N. Mitra

Publications and source records attributed to A. N. Mitra.

At least 19 recordsLinked to original sources

arXiv2012

Field-control, phase-transitions, and life's emergence

Instances of critical-like characteristics in living systems at each organizational level as well as the spontaneous emergence of computation (Langton), indicate the relevance of self-organized criticality (SOC). But extrapolating complex bio-systems to life's origins, brings up a paradox: how could simple organics--lacking the 'soft matter' response properties of today's bio-molecules--have dissipated energy from primordial reactions in a controlled manner for their 'ordering'? Nevertheless, a causal link of life's macroscopic irreversible dynamics to the microscopic reversible laws of statistical mechanics is indicated via the 'functional-takeover' of a soft magnetic scaffold by organics (c.f. Cairns-Smith's 'crystal-scaffold'). A field-controlled structure offers a mechanism for bootstrapping--bottom-up assembly with top-down control: its super-paramagnetic components obey reversible dynamics, but its dissipation of H-field energy for aggregation breaks time-reversal symmetry. The responsive adjustments of the controlled (host) mineral system to environmental changes would bring about mutual coupling between random organic sets supported by it; here the generation of long-range correlations within organic (guest) networks could include SOC-like mechanisms. And, such cooperative adjustments enable the selection of the functional configuration by altering the inorganic network's capacity to assist a spontaneous process. A non-equilibrium dynamics could now drive the kinetically-oriented system towards a series of phase-transitions with appropriate organic replacements 'taking-over' its functions.

q-bio.OT↗

arXiv2012

Can Environmental Decoherence be Reversed for an Open Quantum System in a Magnetic field ?

A simple model is considered for an open system consisting of an aggregation of magnetic particles (like greigite) in the presence of a magnetic field (H), and interacting linearly with a bath of 3D harmonic oscillators. Using the Feynman-Vernon formalism, as given in Weiss (termed FVW), the time-evolved reduced density matrix (after eliminating the bath d.o.f.'s), is examined for environmental decoherence as defined in the FVW formalism. While decoherence is usually positive for most two-way couplings with the enviroment, it is found that a $three-way$ interaction involving the system plus bath plus H-field all together, can facilitate a $reversal$ of sign of this quantity! This may have implications for quantum coherence based phenomena on the origins of life.

cond-mat.mes-hall↗

arXiv2012

Mathematics : The Language of Science

The purpose of this essay is to bring out the unique role of Mathematics in providing a base to the diverse sciences which conform to its rigid structure. Of these the physical and economic sciences are so intimately linked with mathematics, that they have become almost a part of its structure under the generic title of Applied Mathematics. But with the progress of time, more and more branches of Science are getting quantified and coming under its ambit. And once a branch of science gets articulated into a mathematical structure, the process goes beyond mere classification and arrangement, and becomes eligible as a candidate for enjoying its predictive powers! Indeed it is this single property of Mathematics which gives it the capacity to predict the nature of evolution in time of the said branch of science. This has been well verified in the domain of physical sciences, but now even biological sciences are slowly feeling its strength, and the list is expanding.

physics.pop-ph↗

arXiv2011

QFT In Physical Systems: Condensed Matter to Life Sciences

A panoramic view is given of the applications of QFT to diverse areas of physics, beginning with the concepts of QED Vacuum as well as of electron self-energy and renormalization. The related concepts of the degenerate vacuum, spontaneous symmetry breaking (SSB)and Nambu-Goldstone bosons, together with their applications to condensed matter physics and quasi particles are outlined. The possibilities of application to life sciences are also examined. Finally the alternative method of Path integrals for introducing QFT is briefly indicated.

quant-ph↗

arXiv2011

Consciousness: A Direct Link with Life's Origin?

Inspired by the Penrose-Hameroff thesis, we are intuitively led to examine an intriguing correspondence of 'induction' (by fields), with the complex phenomenon of (metabolism-sustained) consciousness: Did sequences of associated induction patterns in field-susceptible biomatter have simpler beginnings?

physics.hist-ph↗

arXiv2010

Efimov Trimers : Analytic Solution Via Separable Potentials

The exact dynamical equation for Efimov trimers in the short range limit of dimer resonances is derived via Yamaguchi separable potentials. This equation which overcomes the non-uniqueness problem of zero-range potentials, closely resembles one derived recently by Gogolin et al, with no further assumptions, and hence enjoys all the benefits of the latter results.

quant-ph↗

arXiv2010

Magnetism, FeS colloids, and Origins of Life

A number of features of living systems: reversible interactions and weak bonds underlying motor-dynamics; gel-sol transitions; cellular connected fractal organization; asymmetry in interactions and organization; quantum coherent phenomena; to name some, can have a natural accounting via $physical$ interactions, which we therefore seek to incorporate by expanding the horizons of `chemistry-only' approaches to the origins of life. It is suggested that the magnetic 'face' of the minerals from the inorganic world, recognized to have played a pivotal role in initiating Life, may throw light on some of these issues. A magnetic environment in the form of rocks in the Hadean Ocean could have enabled the accretion and therefore an ordered confinement of super-paramagnetic colloids within a structured phase. A moderate H-field can help magnetic nano-particles to not only overcome thermal fluctuations but also harness them. Such controlled dynamics brings in the possibility of accessing quantum effects, which together with frustrations in magnetic ordering and hysteresis (a natural mechanism for a primitive memory) could throw light on the birth of biological information which, as Abel argues, requires a combination of order and complexity. This scenario gains strength from observations of scale-free framboidal forms of the greigite mineral, with a magnetic basis of assembly. And greigite's metabolic potential plays a key role in the mound scenario of Russell and coworkers-an expansion of which is suggested for including magnetism.

cond-mat.soft↗

arXiv2009

Magnetism, entropy, and the first nano-machines

The efficiency of bio-molecular motors stems from reversible interactions $\sim$ $k_B T$; weak bonds stabilizing intermediate states (enabling $direct$ conversion of chemical into mechanical energy). For their (unknown) origins, we suggest that a magnetically structured phase (MSP) formed via accretion of super-paramagnetic particles (S-PPs) by magnetic rocks on the Hadean Ocean floor had hosted motor-like diffusion of ligand-bound S-PPs through its template-layers; its ramifications range from optical activity to quantum coherence. A gentle flux gradient offers both detailed-balance breaking non-equilibrium and $asymmetry$ to a magnetic dipole, undergoing infinitesimal spin-alignment changes. Periodic perturbation of this background by local H-fields of template-partners can lead to periodic high and low-template affinity states, due to the dipole's magnetic degree of freedom. An accompanying magnetocaloric effect allows interchange between system-entropy and bath temperature. We speculate on a magnetic reproducer in a setting close to the mound-scenario of Russell and coworkers that could evolve bio- ratchets.

cond-mat.soft↗

arXiv2007

Dynamics Of Proton Spin : Role Of $qqq$ Force

The analytic structure of the $qqq$ wave function, obtained recently in the high momentum regime of QCD, is employed for the formulation of baryonic transition amplitudes via quark loops. A new aspect of this study is the role of a direct ($Y$-shaped, Mercedes-Benz type) $qqq$ force in generating the $qqq$ wave function. The dynamics is that of a Salpeter-like equation (3D support for the kernel) formulated covariantly on the light front, a la Markov-Yukawa Transversality Principle (MYTP) which warrants a 2-way interconnection between the 3D and 4D Bethe-Salpeter (BSE) forms for 2 as well as 3 fermion quarks. The dynamics of this 3-body force shows up through a characteristic singularity in the hypergeometric differential equation for the 3D wave function $ϕ$, corresponding to a $negative$ eigenvalue of the spin operator $i σ_1.σ_2\times σ_3$ which is an integral part of the $qqq$ force. As a first application of this wave function to the problem of the proton spin anomaly, the two-gluon contribution to the anomaly yields an estimate of the right sign, although somewhat smaller in magnitude. Keywords: 3bodyforce; proton-spin; 2gluon anomaly; fractional correction $θ$

hep-ph↗

arXiv2007

Can magnetism-assisted quasiperiodic structures in Russell-FeS `bubbles' offer a quantum coherent origin of life?

This paper seeks to expand the scope of the alkaline seepage site hydrothermal mound scenario of Russell et al, by appealing to its wider canvas for hypothesizing self-assembly of gregite clusters via interplay of forces within the gel phase of FeS membranes: directed heat transport a la Rayleigh-Benard convection for dissociation, vs oriented attachment (small clusters) and magnetic forces (large clusters) for association, the latter assisted by magnetic mound constituents. The directed movement of tiny clusters through cluster layers are reminiscent of processes like budding, molecular motors, pre-RNA world on the lines of Cairns-Smith's hypothesis, and optical polarity. Higher rate of (soft) multinucleate formation vs growth rate of (rigid) microcrystals, correlates with icosahedral (forbidden crystallographically!) framboidal morphology. This pattern indicates a link to phylotaxis, thus reinforcing the quasi-periodicity connection which can provide a natural access to features like surface limit, anomalous transport and low thermal conductivity, while facilitating diffusion through clusters. And magnetism offers a hierarchy of features: primordial multicellularity; phase correlations of assembled molecules; overcoming thermal decoherence. These dynamical nested structures offer possibilities for iterative computations, adaptive learning, and coherent quantum searches. The link between enzymatic FeS clusters and the Hadean ocean floor is seen as part of a larger conceptual framework uncovering a role for Magnetism and the Origin of Life.

cond-mat.soft↗

arXiv2007

Foundations Of Quantum Theory Revisited

After giving a panoramic view of the " text-book " interpretation of the new quantum mechanics, as a sequel to the old quantum theory, the conceptual basis of quantum theory since the Copenhagen Interpretation is reviewed in the context of various proposals since Einstein and Niels Bohr, designed to throw light on possible new facets bearing on its foundations, the key issues to its inherent "incompleteness" being A) measurement, and B) quantum non-locality. A related item on measurement, namely Quantum Zeno (as well as anti-Zeno) effect is also reviewed briefly. The inputs for the new facets are from some key Indian experts : S.M. Roy, V. Singh ; D. Home; B. Misra; C.S. Unnikrishnan

quant-ph↗

arXiv2007

Spin Dynamics Of $qqq$ Wave Function On Light Front In High Momentum Limit Of QCD : Role Of $qqq$ Force

The contribution of a spin-rich $qqq$ force (in conjunction with pairwise $qq$ forces) to the analytical structure of the $qqq$ wave function is worked out in the high momentum regime of QCD where the confining interaction may be ignored, so that the dominant effect is $Coulombic$. A distinctive feature of this study is that the spin-rich $qqq$ force is generated by a $ggg$ vertex (a genuine part of the QCD Lagrangian) wherein the 3 radiating gluon lines end on as many quark lines, giving rise to a (Mercedes-Benz type) $Y$-shaped diagram. The dynamics is that of a Salpeter-like equation (3D support for the kernel) formulated covariantly on the light front, a la Markov-Yukawa Transversality Principle (MYTP) which warrants a 2-way interconnection between the 3D and 4D Bethe-Salpeter (BSE) forms for 2 as well as 3 fermion quarks. With these ingredients, the differential equation for the 3D wave function $ϕ$ receives well-defined contributions from the $qq$ and $qqq$ forces. In particular a $negative$ eigenvalue of the spin operator $i σ_1.σ_2\times σ_3$ which is an integral part of the $qqq$ force, causes a characteristic singularity in the differential equation, signalling the dynamical effect of a spin-rich $qqq$ force not yet considered in the literature. The potentially crucial role of this interesting effect vis-a-vis the so-called `spin anomaly' of the proton, is a subject of considerable physical interest.

hep-ph↗

arXiv2006

Duality : A Bridge Between Physics And Philosophy?

A generalized view of Duality is offered as a bridge between physical sciences and the more abstract philosophical dimensions bordering on mysticism. To that end several examples of duality are first cited from from conventional physics sectors to illustrate the obvious powers of this principle. These include items from reciprocity in Newtonian mechanics to the problem of measurement duality that characterizes quantum mechanics. It is also noted that the latter has acquired a renewed interest in recent times, consequent on the emergence of new experimental techniques for testing the actual laboratory outcomes of traditional gedanken experiments, hitherto taken for granted. Against this background, the Duality principle is sought to be extended to the mystical domain, with convincing examples from various human level experiences.

physics.gen-ph↗

arXiv2005

Einstein And The Evolving Universe

A panoramic view, preceded by a short background of Newtonian mechanics and Maxwellian electrodynamics, is offered on the extent of how Einstein's space-time geometry, believed to be central to an understanding of the structure of the universe, is overshadowed by several hitherto unheard of features like dark matter and dark energy, that seem to be necessary, but by no means sufficient, for a more complete picture.

gr-qc↗

arXiv2004

T-Dependent Dyson- Schwinger Equation In IR Regime Of QCD: The Critical Point

The quark mass function $Σ(p)$ in QCD is revisited, using a gluon propagator in the form $1/(k^2 + m_g^2)$ plus $2μ^2/ (k^2 + m_g^2)^2$, where the second (IR) term gives linear confinement for $m_g = 0$ in the instantaneous limit, $μ$ being another scale. To find $Σ(p)$ we propose a new (differential) form of the Dyson-Schwinger Equation (DSE) for $Σ(p)$, based on an infinitesimal $subtractive$ Renormalization via a differential operator which $lowers$ the degree of divergence in integration on the RHS, by $TWO$ units. This warrants $Σ(p-k)\approx Σ(p)$ in the integrand since its $k$-dependence is no longer sensitive to the principal term $(p-k)^2$ in the quark propagator. The simplified DSE (which incorporates WT identity in the Landau gauge) is satisfied for large $p^2$ by $Σ(p)$ = $Σ(0)/(1 + βp^2)$, except for Log factors. The limit $p^2 =0$ determines $Σ_0$.A third limit $p^2 = -m_0^2$ defines the $dynamical$ mass $m_0$ via $Σ(im_0) = + m_0$. After two checks ($f_π= 93\pm 1 MeV $ and $ $= $(280 \pm 5 MeV)^3$), for $1.5<β<2$ with $Σ_0=300 MeV$, the T- dependent DSE is used in the real time formalism to determine the "critical" index $γ= 1/3$ analytically, with the IR term partly serving for the $H$ field. We find $T_c = 180 \pm 20 MeV$ and check the vanishing of $f_π$ and $ $ at $T_c$. PACS: 24.85.+p; 12.38.Lg; 12.38.Aw.

hep-ph↗

arXiv2002

Minimum Of QCD Effective Action As Test Of QCD Confinement Parameter

A new approach to the non-perturbative regime of QCD is proposed by introducing a (non-hermitian) field $B$ related to the usual gluon field $A$ by $B_μ$ = $(1+ σ\partial_m) A_μ$ where $m$ goes to zero after differentiation, and $σ$ is a parameter which `runs' with momentum ($k$). An exact treatment yields a structure $[1/k^2 + 2μ^2/k^4]$ for the gluon propagator, where $σ^2$ =$πk^4/9μ^2α_s$, showing $linear$ confinement in the instantaneous limit. This propagator was recently employed to evaluate some basic condensates and their temperature dependence (in the cosmological context), which were all reproduced for $μ= 1GeV$ (termed the `confinement scale parameter'), in association with the QCD scale parameter $Λ_{qcd}= 200 MeV$ [hep-ph/0109278]. This paper seeks to provide a formal basis for the ratio $Λ_{qcd} / μ$ by employing the minimality condition for the $integrated$ effective action $Γ$, up to the 2-loop level, using the Cornwall-Jackiw formalism for composite operators. To that end the mass function $m(p)$, determined via the Schwinger-Dyson equation (as a zero of the functional derivative of $Γ$ w.r.t $S_F'$), acts as a feeder, and the stationarity condition on $Γ$ as function of $μ$ and $α_s(μ)$ gives the ratio $Λ/μ$ = 0.246, in fair accord with the value 0.20 given above. Inclusion of a two-loop $Γ$ is crucial for the agreement. \\ Keywords: confinement scale, QCD effective action, minimality condition, $B$-field.

hep-ph↗

arXiv2002

Temperature Dependence of Gluon and Quark Condensates as from Linear Confinement

The gluon and quark condensates and their temperature dependence are investigated within QCD premises. The input for the former is a gauge invariant $gg$ kernel made up of the direct (D), exchange (X) and contact(C) QCD interactions in the lowest order, but with the perturbative propagator $k^{-2}$ replaced by a `non-perturbative $k^{-4}$ form obtained via two differentiations: $ μ^2 \partial_m^2 (m^2+k^2)^{-1}$, ($μ$ a scale parameter), and then setting $m=0$, to simulate linear confinement. Similarly for the input $q{\bar q}$ kernel the gluon propagator is replaced by the above $k^{-4}$ form. With these `linear' simulations, the respective condensates are obtained by `looping' up the gluon and quark lines in the standard manner. Using Dimensional regularization (DR), the necessary integrals yield the condensates plus temperature corrections, with a common scale parameter $μ$ for both. For gluons the exact result is $$ = {36μ^4}π^{-3}α_s(μ^2)[2-γ- 4π^2 T^2/(3μ^2)]$$. Evaluation of the quark condensate is preceded by an approximate solution of the SDE for the mass function $m(p)$, giving a recursive formula, with convergence achieved at the third iteration. Setting the scale parameter $μ$ equal to the universal Regge slope $1 GeV^2$, the gluon and quark condensates at T=0 are found to be $0.586 Gev^4$ and $(240-260 MeV)^3$ respectively, in fair accord with QCD sum rule values. Next, the temperature corrections (of order $-T^2$ for both condensates) is determined via finite-temperature field theory a la Matsubara. Keywords: Gluon Condensate, mass tensor, gauge invariance, linear confinement, finite-temperature, contour-closing. PACS: 11.15.Tk ; 12.38.Lg ; 13.20.Cz

hep-ph↗

arXiv2001

A Dynamical Principle For 3D-4D Interlinkage In Salpeter-like Equations

The half-century old Markov-Yukawa Transversality Principle ($MYTP$) which provides a theoretical rationale for the covariant instantaneous approximation ($CIA$) that underlies all Salpeter-like equations, is generalized to a covariant null-plane ansatz ($CNPA$). A common characteristic of both formulations is an exact 3D-4D interlinkage of BS amplitudes which facilitates a two-tier description: the 3D form for spectroscopy, and the 4D form for transition amplitudes as 4D loop integrals. Some basic applications of $MYTP$ on the covariant null plane (quark mass function, vacuum condensates, and decay constants) are given on the lines of earlier applications to these processes under $CIA$. PACS: 03.65.-w ; 03.65.Co ; 11.10.Qr ; 11.10.St Keywords: Markov-Yukawa Transversality Principle ($MYTP$); Salpeter-like eqs; Cov Instantaneity Ansatz ($CIA$); Cov Null-Plane Ansatz ($CNPA$); 3D-4D interlinkage; Vertex function; 4D loops

hep-ph↗