Note on Energy-Momentum Tensor for General Mixed Tensor-Spinor Fields

This note provides an explicit proof of the equivalence of Belinfante‘s energy-momentum tensor and metric energy-momentum tensor for general mixed tensor-spinor fields.     

Note on Energy-Momentum Tensor for General Mixed Tensor-Spinor Fields

This note provides an explicit proof of the equivalence of Belinfante＇s energy-momentum tensor and metric energy-momentum tensor for general mixed tensor-spinor fields.     

Conservation of the Energy-Momentum

In Relativity the sum of 4?vectors in different points does not generally represent a 4?vector. By using this result, it is shown by simple methods that the total energy-momentum of a system of point particles represents a well-defined 4?vector if the particles do not interact. It is proved that this is equivalent to the no-interaction theorem in Classical Physics. This theorem difficulties the study of a system of interacting particles since it is not even possible to define the total energy-momentum nor the reference frame where the system is at rest. This impediment is avoided by adding to the energy-momentum tensor the stress tensor describing the interaction. As an example, this is applied to a system of charged particles. In the process, the equation of motion for a charged particle including the self-force is formally obtained. However, when a thermodynamic system is analyzed from two different reference frames with a relativistic relative velocity, the interaction between the particles and the walls of the volume cannot be described by means of a covariant stress tensor and consequently the proposed technique is not feasible. Despite the above mentioned drawbacks, a covariant theory of the relativistic transformation laws of the thermodynamic quantities is developed.     

On the Energy-Momentum Problem in Static Einstein Universe

The energy-momentum distributions of Einstein＇s simplest static geometrical model for an isotropic and homogeneous universe are evaluated. For this purpose, Einstein, Bergmann-Thomson, Landau-Lifshitz （LL）, Moller and Papapetrou energy-momentum complexes are used in general relativity. While Einstein and Bergmann-Thomson complexes give exactly the same results, LL and Papapetrou energy-momentum complexes do not provide the same energy densities. The Moller energy-momentum density is found to be zero everywhere in Einstein＇s universe. Also, several spacetimes are the limiting cases considered here.     

Energy-Momentum Properties and the Spin of Short-Lived Particles

The space–time translation property of a stable particle is characterized by a time-like Lorentz vector (E, _k ). We show in this contribution that unstable particles are, in addition, characterized by a space-like Lorentz 4-vector of uncertainties, or spreads, ( E, k). This is true for unstable states created in formation-, in production-, and in decay-experiments. The space-like nature of the spread vector causes a nonzero momentum spread to be present in all Lorentz frames so that there is no Lorentz frame in which the unstable particle is entirely at rest. With the space-like spreadvector ( E, k) in addition to the time-like (E, _k ), also the rotation property of an unstable particle is affected, and unstable states have an uncertainty in their spin. This means neighboring spin states are occupied in addition to the original spin. Experiments are discussed that show a principal limitation of the accuracy of spin measurement from finite lifetimes. Wave functions for unstable particles are discussed, and we show in the example of a short-lived spin-0 state that the appearance of a spin neighbor in the amplitude is proportional to the inverse lifetime.     

N-Soliton Solutions of Modified KdV Equation under Bargmann Constraint

By means of Hirota method, N-soliton solutions of the modified KdV equation under the Bargmann constraint are obtained through solving the Bargmann constraint and the related Lax pair and conjugate Lax pair of the modified KdV equation.     

N-Soliton Solutions of Modified KdV Equation under Bargmann Constraint

By means of Hirota method, N-soliton solutions of the modified KdV equation under the Bargmann constraint are obtained through solving the Bargmann constraint and the related Lax pair and conjugate Lax pair of the modified KdV equation.     

A Note on the Modified KP Hierarchy and its (Yet another) Dispersionless Limit

The modified KP hierarchies of Kashiwara and Miwa are formulated in Lax formalism by Dickey. Their solutions are parametrised by flag varieties. Its dispersionless limit is considered.     

Proof for Gauge Independence of the Energy-Momentum Tensor in Quantum Electrodynamics

Proof is given for gauge independence of the (Belinfante's) symmetric energy-momentum tensor in QED. Under the covariant LSZ-formalism it is shown that expectation values, supplemented with physical state conditions, of the energy-momentum tensor are gauge independent to all orders of the purturbation theory (the loop expansion). A study is also made, in terms of the gauge invariant operators of electron (known as the Dirac's or Steinmann's electron) and photon, in expectation of gauge invariant result without any restriction. It is, however, shown that singling out gauge invariant quantities is merely synonymous to fixing a gauge, then there needs again a use of the asymptotic condition to obtain gauge independent results.     

Einstein's Gravitational Equations in the Friedman Space with Allowance for the Energy-Momentum Tensor

The present paper continues investigations started in [1]. Einstein's gravitational equations are solved based on the generalized nonisotropic Friedman metric with rotation considering the hydrodynamic energy-momentum tensor of an ideal liquid and the equation of motion.     

Can the Local Energy-Momentum Conservation Laws be Derived Solely from Field Equations?

The vanishing of the divergence of the matter stress-energy tensor for General Relativity is a particular case of a general identity, which follows from the covariance of the matter Lagrangian in much the same way as (generalized) Bianchi identities follow from the covariance of the purely gravitational Lagrangian. This identity, holding for any covariant theory of gravitating matter, relates the divergence of the stress tensor with a combination of the field equations and their derivatives. One could thus wonder if, according to a recent suggestion [1], the energy-momentum tensor for gravitating fields can be computed through a suitable rearrangement of the matter field equations, without relying on the variational definition. We show that this can be done only in particular cases, while in general it leads to ambiguities and possibly to wrong results. Moreover, in nontrivial cases the computations turn out to be more difficult than the standard variational technique.     

Note on the virial theorem

It is shown that the usual virial theorem follows directly from the time average of the equation of motion of the function $\text{Σ}\text{i}\text{p}{}_{\mathrm{i}}\text{q}{}_{\mathrm{i}}$, formulated in terms of Poisson brackets.     

Note on the Gartenhaus-Schwartz transformation

It is shown that the Gartenhaus-Schwartz transformation cannot eliminate spurious effects in shell model calculation.     

Energy-Momentum Tensor Form Factors of the Nucleon in Nuclear Matter in the Chiral Soliton Model

In the present talk, we report a recent investigation on the nucleon form factors of the energy-momentum tensor in nuclear matter, based on the in-medium modified chiral soliton model. The results in free space are in agreement with those from other approaches. We have discussed the changes of the energy-momentum tensor form factors in nuclear matter and the modification of the soliton structure due to the surrounding nuclear environment.     

Note on the two-slit experiment

According to the general philosophy of quantum mechanics, a particle whose passage through one of the slits of a two-slit apparatus has been detected does not produce interference. In a previous article this was demonstrated explicitly by solving the Schrödinger equation for a specific model of the detector, but only the first order in the interaction with the detector was considered. In the present note it is shown for the same model that for stronger interactions the interference disappears altogether. When the detector has reached 100% efficiency those particles that have not been detected do not produce interference either, because they are sure to have passed through the other slit.For Oliver Penrose, as a token of esteem.     

Note on the Fried-Yennie gauge

It is pointed out that the renormalization constants and the finite parts of the self energy and the vertex corrections in the infrared-free Fried-Yennie gauge are different, by finite amounts, from those which are computed as the limit of the general covariant gauge. This discrepancy occurs because of the appearance of an infrared divergence in the onmass-shell renormalization. This note provides an example where extra caution is needed in handling the limiting procedure, where an infrared divergence is involved.     

Algebraically Special Gravitational Fields with the Cosmological Constant and Energy-Momentum Tensor of Electromagnetic Radiation

A class of rigorous solutions of the Einstein–Maxwell equations is obtained within the Newman–Penrose formalism for algebraically special gravitational fields with the cosmological constant and energy-momentum tensor of electromagnetic radiation given that the photon flux specifying electromagnetic radiation determines isotropic-geodesic congruence. Designations within the Newman–Penrose formalism and numbers of formulas in references are the same as in [1].     

Correction to Entropy of Schwarzschild Black Hole by Modified Dispersion Relation

Taking WKB approximation to solve the scalar field equation in the Schwarzschild black hole spacetime, we can get the classical momenta. Substituting the classical momenta into state density equation corrected by the modified dispersion relation, we will obtain the number of quantum states with energy less than ω. Then, it is used to calculate the statistical-mechanical entropy of the scalar field in the Schwarzschild black hole spacetime. By taking exact method, we obtained the leader term of entropy which is proportional to the event horizon area and correction terms take the forms of ln A, A ⁻¹ln A, A ⁻¹ and so on.     

Bergmann–Thomson Energy-Momentum Complex for Solutions More General than the Kerr–Schild Class

In a very well-known paper, Virbhadra’s research group proved that the Weinberg, Papapetrou, Landau and Lifhsitz, and Einstein energy-momentum complexes “coincide” for all metrics of Kerr–Schild class. A few years later, Virbhadra clarified that this “coincidence” in fact holds for metrics more general than the Kerr–Schild class. In the present paper, this study is extended for the Bergmann–Thomson complex and it is proved that this complex also “coincides” with those complexes for a more general than the Kerr–Schild class metric.     

Constraint on parity-violating muonic forces

Using the nonobservance of missing mass events in the leptonic kaon decay K→μX, we place a strong constraint on exotic parity-violating gauge interactions of the right-handed muon. By way of illustration, we apply it to an explanation of the proton size anomaly that invokes such a new force; scenarios in which the gauge boson decays invisibly or is long lived are constrained.