arXiv subjects

M. Nowakowski

Publications and source records attributed to M. Nowakowski.

At least 55 records · Page 3Linked to original sources

arXiv2006

Ellipsoidal configurations in the de Sitter spacetime

The cosmological constant $Λ$ modifies certain properties of large astrophysical rotating configurations with ellipsoidal geometries, provided the objects are not too compact. Assuming an equilibrium configuration and so using the tensor virial equation with $Λ$ we explore several equilibrium properties of homogeneous rotating ellipsoids. One shows that the bifurcation point, which in the oblate case distinguishes the Maclaurin ellipsoid from the Jacobi ellipsoid, is sensitive to the cosmological constant. Adding to that, the cosmological constant allows triaxial configurations of equilibrium rotating the minor axis as solutions of the virial equations. The significance of the result lies in the fact that minor axis rotation is indeed found in nature. Being impossible for the oblate case, it is permissible for prolate geometries, with $Λ$ zero and positive. For the triaxial case, however, an equilibrium solution is found only for non-zero positive $Λ$. Finally, we solve the tensor virial equation for the angular velocity and display special effects of the cosmological constant there.

gr-qc↗

arXiv2006

Equilibrium of large astrophysical structures in the Newton-Hooke spacetime

Using the scalar and tensor virial equations, the Lane-Emden equation expressing the hydrostatic equilibrium and small oscillations around the equilibrium, we show how the cosmological constant $Λ$ affects various astrophysical quantities important for large matter conglomeration in the universe. Among others we examine the effect of $Λ$ on the polytropic equation of state for spherically symmetric objects and find non-negligible results in certain realistic cases. We calculate the angular velocity for non-spherical oblate configurations which demonstrates a clear effect of $Λ$ on high eccentricity objects. We show that for oblate as well as prolate ellipsoids the cosmological constant influences the critical mass and the temperature of the astrophysical object. These and other results show that the effect of $Λ$ is large for flat astrophysical bodies.

astro-ph↗

arXiv2005

Faraday's law in the presence of magnetic monopoles

We show that if we consider the full statement of Faraday's law for a closed physical circuit, the standard Maxwell's equations in the presence of electric and magnetic charges have to include in their integral form a mixed term of the form $ρ_m {\bf v}_e^{\perp}$ where $ρ_m$ is the magnetic charge density and ${\bf v}_e^{\perp}$ the perpendicular component of the velocity ${\bf v}_e$ of the electric charge.

physics.class-ph↗

arXiv2005

The Use of the Scattering Phase Shift in Resonance Physics

The scattering phase shift encodes a good amount of physical information which can be used to study resonances from scattering data. Among others, it can be used to calculate the continuum density of states and the collision time in a resonant process. Whereas the first information can be employed to examine the evolution of unstable states directly from scattering data, the second one serves as a tool to detect resonances and their properties. We demonstrate both methods concentrating in the latter case on 'exotic' resonances in pi-pi and pi-K scattering.

hep-ph↗

arXiv2004

Pentaquark Resonances from Collision Times

Having successfully explored the existing relations between the S-matrix and collision times in scattering reactions to study the conventional baryon and meson resonances, the method is now extended to the exotic sector. To be specific, the collision time in various partial waves of K+ N elastic scattering is evaluated using phase shifts extracted from the K+ N --> K+ N data as well as from model dependent T-matrix solutions. We find several pentaquark resonances including some low-lying ones around 1.5 to 1.6 GeV in the P_01, P_03 and D_03 partial waves of K+ N elastic scattering.

hep-ph↗

arXiv2004

Hidden evidence of non-exponential nuclear decay

The framework to describe natural phenomena at their basics being quantum mechanics, there exist a large number of common global phenomena occurring in different branches of natural sciences. One such global phenomenon is spontaneous quantum decay. However, its long time behaviour is experimentally poorly known. Here we show, that by combining two genuine quantum mechanical results, it is possible to infer on this large time behaviour, directly from data. Specifically, we find evidence for non-exponential behaviour of alpha decay of 8Be at large times from experiments.

nucl-th↗

arXiv2004

Evidence of Pentaquark States from K+ N Scattering Data?

Motivated by the recent experimental evidence of the exotic B = S = +1 baryonic state Theta(1540), we examine the older existing data on K+ N elastic scattering through the time delay method. We find positive peaks in time delay around 1.545 and 1.6 GeV in the D03 and P01 partial waves of K+ N scattering respectively, in agreement with experiments. We also find an indication of the J=3/2 Theta* spin-orbit partner to the Theta, in the P03 partial wave at 1.6 GeV. We discuss the pros and contras of these findings in support of the interpretation of these peaks as possible exotics.

nucl-th↗

arXiv2004

Time Delay Plots of Unflavoured Baryons

We explore the usefulness of the existing relations between the $S$-matrix and time delay in characterizing baryon resonances in pion-nucleon scattering. We draw attention to the fact that the existence of a positive maximum in time delay is a necessary criterion for the existence of a resonance and should be used as a constraint in conventional analyses which locate resonances from poles of the $S$-matrix and Argand diagrams. The usefulness of the time delay plots of resonances is demonstrated through a detailed analysis of the time delay in several partial waves of $πN$ elastic scattering.

hep-ph↗

arXiv2003

Time delayed K+ N reactions and exotic baryon resonances

Evidences and hints, both from the theoretical and experimental side, of exotic baryon resonances with B=S, have been with us for the last thirty years. The poor status of the general acceptance of these Z* resonances is partly due to the prejudice against penta-quark baryons and partly due to the opinion that a proof of the existence of exotic states must be rigorous. This can refer to the quality and amount of data gathered, and also to the analytical methods applied in the study of these resonances. It seems then mandatory that all possibilities and aspects be exploited. We do that by analyzing the time delay in K+ N scattering, encountering clear signals of the exotic Z* resonances close to the pole values found in partial wave analyses.

hep-ph↗

arXiv2003

Collision times in pi-pi and pi-K scattering and spectroscopy of meson resonances

Using the concept of collision time (time delay) introduced by Eisenbud and Wigner and its connection to on-shell intermediate unstable states, we study mesonic resonances in pi-pi and pi-K scattering. The time-delay method proves its usefulness by revealing the spectrum of the well-known rho- and K*-mesons and by supporting some speculations on rho-mesons in the 1200 MeV region. We use this method further to shed some light on more speculative meson resonances, among others the enigmatic scalars. We confirm the existence of chiralons below 1 GeV in the unflavoured and strange meson sector.

hep-ph↗

arXiv2002

Newton's laws of motion in form of Riccati equation

We discuss two applications of Riccati equation to Newton's laws of motion. The first one is the motion of a particle under the influence of a power law central potential $V(r)=k r^ε$. For zero total energy we show that the equation of motion can be cast in the Riccati form. We briefly show here an analogy to barotropic Friedmann-Robertson-Lemaitre cosmology where the expansion of the universe can be also shown to obey a Riccati equation. A second application in classical mechanics, where again the Riccati equation appears naturally, are problems involving quadratic friction. We use methods reminiscent to nonrelativistic supersymmetry to generalize and solve such problems

physics.class-ph↗

arXiv2001

Statistical model for pionic partons

We present a model for the structure of the pion. Based on ideas of a recently developed statistical model of the nucleon, we assume the pion to be a gas of partons. The finite-size corrections (FSC) are incorporated through two parameters. Using the same two FSC parameters for the proton and pion we reproduce quantitatively the data on $π^- N \to μ^+ μ^- X$ Drell-Yan production and valence quark distribution of the pion.

hep-ph↗

arXiv1999

Long range neutrino forces in the cosmic relic neutrino background

Neutrinos mediate long range forces among macroscopic bodies in vacuum. When the bodies are placed in the neutrino cosmic background, these forces are modified. Indeed, at distances long compared to the scale $T^{-1}$, the relic neutrinos completely screen off the 2-neutrino exchange force, whereas for small distances the interaction remains unaffected.

hep-ph↗

arXiv1998

Bell-inequalities for $K^0 \bar{K^0}$ Pairs from $Φ$-Resonance Decays

We analyze the premises of recent propositions to test local realism via Bell-inequalities using neutral kaons from $Φ$-resonance decays as entangled EPR-pairs. We pay special attention to the derivation of Bell-inequalities, or related expressions, for unstable and oscillating kaon `quasi-spin' states and to the possibility of the actual identification of these states through their associated decay modes. We discuss an indirect method to extract probabilities to find these states by combining experimental information with theoretical input. However, we still find inconsistencies in previous derivations of Bell-inequalities. We show that the identification of the quasi-spin states via their associated decay mode does not allow the free choice to perform different tests on them, a property which is crucial to establish the validity of any Bell-inequality in the context of local realism. In view of this we propose a different kind of Bell-inequality in which the free choice or adjustability of the experimental set-up is guaranteed. We also show that the proposed inequalities are violated by quantum mechanics.

hep-ph↗

arXiv1998

Higgs- and Goldstone bosons-mediated long range forces

In certain mild extensions of the Standard Model, spin-independent long range forces can arise by exchange of two very light pseudoscalar spin--0 bosons. In particular, we have in mind models in which these bosons do not have direct tree level couplings to ordinary fermions. Using the dispersion theoretical method, we find a $1/r^{3}$ behaviour of the potential for the exchange of very light pseudoscalars and a $1/r^{7}$ dependence if the pseudoscalars are true massless Goldstone bosons.

hep-ph↗

arXiv1998

Long range forces induced by neutrinos at finite temperature

We revisit and extend previous work on neutrino mediated long range forces in a backround at finite temperature. For Dirac neutrinos, we correct existing results. We also give new results concerning spin-dependent as well as spin-independent long range forces associated to Majorana neutrinos. An interesting outcome of the investigation is that, for both types of neutrinos whether massless or not, the effect of the relic neutrino heat bath is to convert those forces into attractive ones in the supra-millimeter scale while they stay repulsive within the sub-millimeter scale.

hep-ph↗

arXiv1996

Space-Dependent Probabilities for $K^0-\bar{K^0}$ Oscillations

We analyze $K^0-\bar{K^0}$ oscillations in space in terms of propagating wave packets with coherent $K_S$ and $K_L$ components. The oscillation probabilities $P_{K^0 \to K^0} (x)$ and $P_{K^0 \to \bar{K^0}} (x)$ depending only on the distance $x$, are defined through the time integration of a current density $j(x,t)$ . The definition is such that it coincides with the experimental setting, thus avoiding some ambiguities and clarifying some controversies that have been discussed recently.

hep-ph↗

arXiv1994

Triplet Higgs bosons at $e^+e^-$ colliders

We investigate the possibility of probing the triplet Higgs boson sector via single charged Higgs production in the process $e^+ e^- \to H^+ l ν_l$, at high energy electron-positron colliders, using the tree level $H^+W^-Z$ coupling which is a unique feature of such models. We find that even LEP-200 can give nontrivial information upto $M_{H^{\pm}} \simeq 120 $ GeV if the doublet -triplet mixing is not restricted by the current value of the $ρ$ parameter which is the case in models with a custodial symmetry. Further we point out that in such models, the 4-body, tree level decay $H^+ \to W^*Z^* \to 4$ fermions dominates and hence provides a very clean signal when the four fermions are leptons. At NLC the discovery range for the charged Higgs in triplet models via this process is $\sim 400$ GeV.

hep-ph↗