Systematics of the α±-decay fine structure in even–even nuclei
Dumitrescu Alexandru, DFT
Abstract:
We describe α-transitions to low-lying states in even–even nuclei with Z > 50, N > 82 using the Coherent State Model (CSM). We reproduce the energy levels and electromagnetic transition rates between the states of the ground band employing two parameters, namely the deformation parameter and the strength of the harmonic CSM Hamiltonian. The B(E2) values are described in terms of an effective charge which depends linearly on the deformation parameter. The treatment of the α-emission process is based on an α–daughter interaction containing a monopole component, calculated through a double folding procedure with a M3Y interaction plus a repulsive core simulating the Pauli principle, and a quadrupole–quadrupole (QQ) interaction. The decaying states are identified with the lowest narrow outgoing resonances obtained through the coupled channels method. The α-branching ratios to 2+ states are reproduced by means of the QQ strength. This interaction strength can be fitted with a linear dependence on the deformation parameter, as predicted by the CSM. The theoretical intensities to 4+ and 6+ states are in reasonable agreement with available experimental data. Predictions are made for spherical, transitional and well deformed even–even α-emitters.
Bibliografie:
D.S. Delion and A. Dumitrescu, At. Data Nucl. Data Tables 101, 1 (2015).
Lucrarea prezentata a fost predata pentru faza 3/2015 a proiectului PN 09 37 0107/2009
Heterojonctiuni semiconductoare in camp laser
Profesor Victor Bârsan
Teoria potentialelor laser imbracate ("laser dressed potentials") isi gaseste aplicatii in nanofizica, prezenta laserului modificand semnificativ miscarea electronilor in heterojonctiuni. Vor fi obtinute rezultate analitice privind nivelele energetice ale electronilor in aceste potentiale laser imbracate.
Raport de faza nr. 4/2015.
Trivial Lagrangians in the Causal Approach
Dan Grigore, DFT
Influence of pairing interaction on the transmission factor in sub-barrier fusion reactions
Radu A. Gherghescu, DFT
The pairing interaction energy has been calculated using the Bardeen-Cooper-Schrieffer formalism. A law of variation for the pairing strength parameter G has been introduced in order to take into account the binary character of the process. Then the BCS system of equations has been solved and the gap ∆ and the Fermi level for the system of quasi-particles have been calculated as solutions. The total energy is obtained as the sum of the liquid drop part (macroscopic term) and the microscopic corrections (shell and pairing). The pairing energy is oposite to the shell part, so that it smoothes the large var iations due to deformed shell closures. The pairing interaction influences the tensor of inertia via the occupation probabilities. As the final result, the penetrability, defined as the transmission factor in the sub-barrier fusion cross section, is calculated. The reaction pairs with one magic and/or double magic partner are the most favourable (highest penetrability values) for the synthesis of superheavy nuclei.
Spontaneous fission of superheavy nuclei
Dorin N.Poenaru, DFT
The decimal logarithm of spontaneous fission half-life of the superheavy nucleus 286Fl experimentally determined is log10T expf(s)=−0.523. Other similar nuclei are 282,284Cn with log10 T expf(s) =−3.086,−0.980. We present a method to calculate the half-life based on the cranking inertia and the deformation energy, functions of two independent surface coordinates, using the best asymmetric two center shell model (ATCSM). For the statics the Strutinsky’s macroscopic-microscopic method uses the Yukawa-plus-exponential model and the ATCSM to determine the shell and BCS pairing corrections. Dynamics implies the cranking inertia tensor where again the ATCSM and the pairing are the main ingredients. The least action trajectory is determined in the plane (R, η) where R is the separation distance of the fission fragments and η is the mass asymmetry. We may find a sequence of several trajectories one of which gives the least action and the half-life. Zero point vibration energy is the adjusted parameter. The shape param etrization with two deformation coordinates (R, η) and the radius of the light fragment, R2, exponentially decreasing with R is compared with the simpler one, in which R2=constant. We conclude that the latter is closer to the reality and remainds us about the alpha or cluster preformation at the nuclear surface.
Symmetries of physical systems using their
geometrical properties
Mihai Visinescu, DFT, IFIN-HH
Abstract
An important point of interest in physics is to identify constants of motion or conserved quantities of a system. The equations controlling the symmetries are quite intricate and to get their solutions by solving the corresponding system of partial differential equations is a very difficult task. We describe a method for constructing the constants of motion on some spaces of interest using their geometrical properties. Finally we discuss the integrability of geodesic motions in these spaces.
References
[1] V. Slesar, M. Visinescu, G. E. Vîlcu, Phys. Scr. 89, 125205 (2014)
[2] V. Slesar, M. Visinescu, G. E. Vîlcu, EPL–Europhys. Lett. 110, 31001 (2015)
[3] E. M. Babalic, M. Visinescu, Mod. Phys. Lett. A, 30, 1550180 (2015)
[4] V. Slesar, M. Visinescu, G. E. Vîlcu, Annals of Physics 361, 548 (2015)
[5] V. Slesar, M. Visinescu, G. E. Vîlcu, Rom. J. Phys. 61, 260 (2016)
SEENET-MTP - A Network for the Balkans
Goran S. Djordjević
Department of Physics & SEENET-MTP Office
Faculty of Science and Mathematics, University of Niš
Višegradska 33, 18000 Niš, Serbia
This email address is being protected from spambots. You need JavaScript enabled to view it. ; This email address is being protected from spambots. You need JavaScript enabled to view it.
Abstract:
Recognizing the necessity and importance of providing a framework for the institutional capacity building in Mathematical and Theoretical Physics that would cover different educational levels in Science, education and bridge the gap between Southeastern and Western European scientific community, the SEENET-MTP stems from the BW2003 WORKSHOP Mathematical, Theoretical and Phenomenological Challenges Beyond the Standard Model: PERSPECTIVES OF BALKANS COLLABORATION sponsored by the UNESCO Office in Venice and held in 2003, in Vrnjačka Banja (Serbia).
The Network has been a natural continuation of Prof. Julius Wess’ initiative: Scientists in Global Responsibility (Wissenschaftler in Global Verantwortung - WIGV), started in 1999. Within the years 2004-2015: 21 institutions from 11 SEE countries, 13 partner institutions all over the world and about 360 individuals joined the Network (http://www.seenet-mtp.info):.
Background and motivation of the Network establishing are highlighted. Aims, objectives and structure of the Network are presented. The main activities and results: projects, conferences, schools and seminars, monograph publications, joint papers and proceedings are listed and elaborated.
The current-ongoing programs as: CERN - SEENET-MTP PhD program, ICTP-SEENET project “Cosmology and strings”, UNESCO – “Lights of the World” project, joint actions with EPS (and its Committee of European integration), BPU and other are considered and offered for discussion and upgrading.
References and links:
- R. Constantinescu, G.S. Djordjevic, Education and Research in the SEENET‐MTP Regional Framework for Higher Education in Physics, AIP Conf. Proc. 1203, 1261 (2010) http://dx.doi.org/10.1063/1.3322351
- G. Djordjevic, I. Antoniadis, Balkan Summer Institute 2011 convenes by the blue Danube, CERN Courier, vol. 51, no. 9 (2011)
- G. S. Djordjevic, Noncommutativity and Humanity - Julius Wess and His Legacy, Int. Journal of Modern Physics: Conference Series Vol. 13 (2012) p. 66–85
- L. Moeller, Julius Wess - a Scientist in Global Responsibility, Int. Journal of Modern Physics: Conference Series Vol. 13 (2012) p. 141-148
- G. Djordjevic, 10 Years of the SEENET-MTP, e-EPS, June 2013, www.epsnews.eu/2013/06/seenet-mtp/
- G. Djordjevic, SEENET-MTP Network celebrate its 10th year during the BW2013, e-EPS, March 2013, www.epsnews.eu/2013/03/seenet-mtp-10th-year-bw2013/
- G.S. Djordjevic, A network for the Balkans, CERN Courier, December 2013, pp. 21–23 http://cerncourier.com/cws/article/cern/55332
- SEE-CEI-ERA - Towards the integration of the physics community in CEI countries into the ERA, http://see-cei-era.seenet-mtp.info/
- R. Constantinescu, G. Djordjevic, D. Lee, Integration of the physics community in CEI countries into the ERA, e-EPS, July 2014, www.epsnews.eu/2014/07/integration-of-the-physics-community-in-cei-countries-into-the-era/
- A. Proykova, International Workshop EPS-CEI-UNESCO, e-EPS, October 2014
www.epsnews.eu/2014/10/workshop-eps-cei-unesco/ - D. Lee, Workshop on physics education at ICTP, Trieste, e-EPS, March 2015,
www.epsnews.eu/2015/03/report-on-the-workshop-on-physics-education/ - http://www.unesco.org/new/fileadmin/MULTIMEDIA/FIELD/Venice/pdf/news/SEE-Networks_note.pdf
- CERN – SEENET-MTP PhD Training Program, http://phd.seenet-mtp.info
Sanda Adam (DFT si IUCN Dubna) si George Adam (DFT si IUCN Dubna)
A report of activity at JINR Dubna in 2015
SUMMARY:
The report of activity of Gh. Adam and S. Adam at JINR Dubna on 2015 is presented. It is structured in two parts.
Part one: Romanian Participation@Laboratory of Information Technologies & Romanian Youth@JINR (based on the presentation done at the Mini Simposium „60 years of Romanian participation at JINR Dubna“, 03.11.2015)
Part two: Control Decisions in the Bayesian Automatic Adaptive Quadrature (based on the presentation at the ROLCG 2015 Conference, Cluj-Napoca, October 28-30, 2015)
Three topics in the Bayesian automatic adaptive quadrature are discussed:
• (1) The accuracy specifications controlling the error tolerance of the derived output need a twofold scrutiny:
- check of the reliability of the accuracy specification at input;
- check for the need of integrand dependent accuracy bounds.
• (2) Avoidance of overcomputing & minimization of the hidden floating point loss of precision asks for the consideration of three classes of integration domain lengths endowed with specific quadrature sums: microscopic (trapezoidal rule), mesoscopic (Simpson rule), and macroscopic (quadrature sums of high algebraic degrees of precision).
• (3) Sensitive diagnostic tools for the Bayesian inference on macroscopic ranges, coming from the use of Clenshaw-Curtis quadrature, are illustrated
Rolul inertiei magnetice in dinamica disipativa a macrospinului
Dr. Mihaela-Cristina Ciornei (Timisoara)
A uniform asymptotic approximation of the 3D scattering wave function for a non-central Coulomb-like potential
Nicolae Grama
Department of Theoretical Physics, Horia Hulubei National Institute for Nuclear Physics and Engineering- Bucharest, Romania
Abstract:
A uniform asymptotic approximation of the 3D scattering wave function for a non-central Coulomb-like potential is obtained. It is based on a new Ansatz of the form of the solution that uses an etalon function generated by the problem itself, rather than a special function. First the 3D WKB approximation of the scattering wave function for the non-central Coulomb-like potential is obtained. This approximation is valid on the whole range of the variables, except the caustics.
The uniform approximation eliminates the shortcoming of the 3D WKB approximation, being valid on the whole range of the variables, including the caustics. The scattering amplitude for the non-central Coulomb-like potential is obtained.
An introduction to string phenomenology and extra dimensions
Prof. Ignatios Antoniadis
Univ Pierre et Marie Curie - Paris & Albert Einstein Centre - University of Bern
Abstract:
I will present the physical context and motivations for strings, branes and extra dimensions. I will discuss both the possibilities of high and low string scale and the main experimental implications.
(2 lectures: DFT seminar room, Thu 22 Oct, 11:00 - 12:00 and 14:00 - 15:00).
From two-dimensional electron gas to localized charge: dynamics of polaron
formation in organic semiconductors
Claudiu Caraiani, Univ. Bucuresti
Abstract:
Electronic transport in organic semiconductors is mediated by localized polarons. However, the dynamics on how delocalized electrons collapse into polarons through electron-nuclear interaction is not well known. In this work, we use time- and angle-resolved photoemission spectroscopy to study polaron formation in titanyl phthalocyanine deposited on Au(111) surfaces. Electrons are optically excited from the metal to the organic layer via the image potential state, which evolves from a dispersive to a nondispersive state after photoexcitation. The spatial size of the electrons is determined from the band structure using a tight-binding model. It is observed that the two-dimensional electron wave collapses into a wave packet of a size about 3 nm within 100 fs after photoexcitation.
Tsallis statistics approach to hadron transverse momentum distributions in high-energy collisions
Dr. A. Parvan (DFT, IFIN-HH, Bucharest & BLTP, JINR, Dubna)
Abstract:
The transverse momentum distributions measured by the ALICE, ATLAS and CMS Collaborations at the LHC are analyzed in the framework of both the non-extensive Tsallis statistics and the ordinary Boltzmann-Gibbs statistics. The problems of the thermodynamic foundation for the Tsallis statistics and, in particular, the conditions for the thermodynamic self-consistency of the nonrelativistic Tsallis statistics approach in the microcanonical, canonical and grand canonical ensembles are discussed.
Causal Structure and Spacetime Singularities
Ovidiu Cristinel Stoica, DFT IFIN-HH
Abstract:
In General Relativity the metric can be recovered from the structure of the lightcones and a measure giving the volume element. Since the causal structure seems to be simpler than the Lorentzian manifold structure, this suggests that it is more fundamental. But there are cases when seemingly healthy causal structure and measure determine a singular metric. Here it is shown that this is not a bug, but a feature, because big-bang and black hole singularities are instances of this situation. But while the metric is special at singularities, being singular, the causal structure and the measure are not special in an explicit way at singularities. Therefore, considering the causal structure more fundamental than the metric provides a more natural framework to deal with spacetime singularities.
Proton-neutron pairing and quartet condensation in nuclei
Nicolae Sandulescu
National Institute of Physics and Nuclear Engineering, Bucharest, Romania
The common treatment of proton-neutron pairing in N @ Z nuclei relies on Cooper pairs and mean-field BCS-type models. However, the nuclear interaction can induce, through the isospin conservation, quartet correlations of alpha type which might compete with the Cooper pairs. In fact, for any isovector pairing interactions the ground state of N=Z systems is accurately described not by Cooper pairs but in terms of collective quartets [1]. Cooper pairs and quartets can however coexist in isospin asymmetric systems with N>Z. In this case the ground state of the isovector pairing Hamiltonian can be described with high precision as a condensate of alpha-like quartets to which it is appended a condensate of Cooper pairs built with the excess neutrons [2,3]. Quartet models appear to be also appropiate for treating the competition between the isoscalar and the isovector proton-neutron pairing in N=Z nuclei [4,5], predicting results which are very different from the standard BCS models. In fact, as shown recently, quartetting is more important and more general than expected, persisting for any realistic nuclear forces [6,7].
1. N. Sandulescu, D.Negrea, J. Dukelski, C. W. Johnson, Phys. Rev.C 85, 061303(R) (2012)
2. N. Sandulescu, D. Negrea, C. W. Johnson,Phys. Rev. C86, 041302 (R) (2012)
3. D. Negrea and N. Sandulescu, Phys. Rev. C90, 024322 (2014)
4. M. Sambataro, N. Sandulescu and C. W. Johnson, Phys. Lett. B770, 137(2015)
5. N. Sandulescu, D. Negrea, D. Gambacurta, Phys. Lett. B (2015), accepted
6. M. Sambataro and N. Sandulescu, Phys. Rev. C91, 064318 (2015)
7. M. Sambataro and N. Sandulescu, Phys. Rev. Lett. 115, 112501 (2015)
From Horismos to Relativistic Spacetime
Cristinel Stoica, DFT IFIN-HH
Abstract:
A set endowed with a reflexive relation has surprisingly many features in common with the causal structure of a spacetime in General Relativity. If we identify this relation as the relation between lightlike separated events (the horismos relation), we can construct in a natural way the entire causal structure: causal and chronological relations, causal curves, and a topology. By imposing a simple additional condition, the structure gains a definite number of dimensions. This construction works both with continuous and discrete spacetimes. The dimensionality is obtained with ease also in the discrete case, in contrast with the causal set approach, which starts with a discrete set of events endowed with partial order relation representing the causal relation, but has severe difficulties in recovering the number of dimensions. Other simple conditions make it into a differentiable manifold with a conformal structure (the metric up to a scaling factor) just like in General Relativity. This structure provides a simple and general reconstruction of the spacetime in General Relativity, which normally requires a hierarchy of structures: topological structure, differential structure, geometric structure (which in turn can be decomposed in the conformal structure, giving the causal relations, and the volume element).
Double-beta decay: to be or not to be
Prof. Mihai Horoi
Central Michigan University
Abstract:
The elusive process of neutrinoless double-beta decay is hunted by the scientific community for about 80 years, and the hunt intensified in the last years. If observed, it would add a new piece of information to the Standard Model of particle physics, namely that the neutrinos are identical with their antiparticles, and that the lepton number is violated by two units. In my talk I will review the particle physics aspects, and the nuclear structure aspects of this interesting process.
Tensorial models and renormalization
Joseph Bengeloun
AEI Potsdam
Abstract:
The tensor model approach for quantum gravity is reviewed. I will then discuss the construction of field theories built over tensors. These are nonlocal quantum field theories endowed with specific interactions which are spanned by convolutions of tensors and which represent simplicial manifolds. The theory expands in Feynman graphs that one dually associates with simplicial complexes. When the range of indices of the tensors becomes infinite, the resulting quantum amplitudes might diverge. A perturbative renormalization program is quickly presented before listing the next challenges of this proposal.
Excitatii colective in nanostructuri si dependenta proprietatilor fizice de temperatura
Sergiu Cojocaru
DFT / IFIN-HH
Abstract:
Este prezentata o metoda de investigare a efectului conditiilor la limita asupra oscilatiilor retelei cristaline in nanostructuri, in special al lantului atomic. Este obtinuta forma analitica a dependentei de temperatura a caldurii specifice si este discutat cuplajul centrului de masa cu restul gradelor de libertate. Este descrisa interactia fononilor cu electronii in structuri quasi-bidimensionale de tip metal-izolator utilizate in micro-racitoare electronice si este determinata puterea de disipare a energiei electronilor functie de temperatura.
Parametric resonance in molecular rotation spectra
Raport Faza Nucleu-ELI 2015
Prof. Marian Apostol
DFT/IFIN-HH
Abstract:
The molecular rotation spectra, resulted from the coupling of an external time-dependent electric field with the molecular electric dipole moment, are discussed in a few particular conditions which may be of some experimental interest. First, the classical dynamics of the molecule viewed as a spherical pendulum is presented, and the quantum-mechanical rotation spectrum is derived (transitions between rotation levels) at finite temperatures. Second, the same problem is analyzed in the presence of a static external electric field, in two particular cases, namely, high- and low-field. For a high static electric field the dipoles are quenched in equilibrium positions, giving rise to a macroscopic electric polarization; they may execute small rotations and vibrations around these positions, which may exhibit a parametric resonance. This situation may be relevant for polar matter (like pyroelectrics, ferroelectrics), or for heavy impurities embedded in a polar solid, which may provide high local static electric fields. A similar situation may also appear for a weak static electric field. Next, the dipolar interaction is analyzed in polar condensed matter, where it is shown that new polarization modes may appear for a spontaneous macroscopic value of the electric polarization (these modes are tentatively called "dipolons"); one of the polarization modes is also related to a parametric resonance. The extension of these considerations to magnetic dipoles is also briefly discussed.
Lifetimes of Superheavy Nuclei around Double Magic Nucleus 270108HS162
Ion SILISTEANU, Claudia I. ANGHEL
DFT / IFIN-HH
Abstract
Background: The most important decay modes for heavy and superheavy nuclei (SHN) are the α-decay and spontaneous fission. This work investigates the evolution and the competition of these modes from the proton rich to neutron rich SHN .
Purpose: Define, extrapolate and compare approximation schemes and methods for half-lives incorporating the essential physics of nuclear process. To compile measurements and theoretical half-lives and to tabulate recommended values along with total half-lives.
Method: To evaluate and compare the alpha decay and fission half-lives using microscopic-macroscopic and phenomenological methods. The alpha and fission half-lives are obtained in terms of a minimal set of parameters determined from the fit of experimental data and results of the rate theory.
Results: A summary of the experimental and calculated α-decay and spontaneous fission half-lives of the isotopes of super-heavy elements with Z=104-112 is presented. Some half-lives extrapolations for nuclides not yet known are obtained.
Conclusions: The α-decay and fission are powerful tools for investigating the detailed aspects of the nuclear structure and reaction dynamics. The decay properties of SHN are strongly connected with the single-particle structure of valence nucleons.
Comparison of experimental and calculated results provides insight into the accuracy of modern approaches for the structure of SHN with valence nucleons outside the doubly magic core.
Key words: Super-heavy nuclei (SHN); α-decay, clustering and scattering amplitudes; resonance tunneling; decay-rates systematics.
New solutions in M-theory compactifications to 3 dimensions
Andrei Micu
DFT / IFIN-HH
Abstract:
We are interested to find supersymmetric solutions for M-theory compactifications to 3 dimensions with N=2 supersymmetry which generate potentials for M2 branes. For this purpose we first study what further conditions a supersymmetric configuration has to satisfy in order to represent a solution of the full system of equations of motion. We present a general result for N=2 compactifications to 3d. Further we propse a new flux which has the potential to lead to a fully consistent background which also generates a potential for M2 branes.
Pion production in heavy-ion collisions and the symmetry energy
Dan Cozma
DFT / IFIN-HH
Abstract:
The multiplicity ratio of pi-/pi+ meson in heavy-ion collisions at few-hundred MeV impact energy has been proven to be an observable sensitive to the isovector part of the equation of state of nuclear matter (asy-EoS). However, constraints for the stiffness of the asy-EoS extracted using this observable are extremely model dependent [1] and additionally are often in contradiction with those extracted from elliptic flow observables [2,3]. The present study focuses on an upgrade of the Tuebingen QMD transport model achieved by enforcing the conservation of energy at a local (LEC) or global (GEC) level in collision, decay and absorption processes by including contributions due to in-medium density, isospin asymmetry and momentum dependent baryon potential energies for both nucleons and baryonic resonances, which has as an effect the in-medium modification of particle production thresholds. The LEC scenario is similar to the one recently published in Ref. [4]. It is shown that compatible constraints for asy-EoS stiffness from pi-/pi+ multiplicity ratio and elliptic flow can be extracted only within the GEC scenario. However, an important dependence of the pi-/pi+ observable on the strength of the isovector part of the Delta(1232) isobar potential is also demonstrated [5]. The lack of information on this quantity prevents at present a precise extraction of the value for the asy-EoS stiffness employing the mentioned observable. A remedy of this situation will however make experimental information on pi-/pi+ multiplicity ratio in heavy-ion collisions close to or below pion
production threshold extremely valuable.
[1] Z.G. Xiao et al., Eur. Phys. J. A50, 37 (2014);
[2] P. Russotto et al., Phys. Lett. B 697, 471 (2011);
[3] M.D. Cozma et al., Phys. Rev. C 88, 044912 (2013);
[4] T. Song and C.M. Ko, arXiv: 1403.7364;
[5] M.D. Cozma, arXiv: 1409.3110.
Fields at spacetime singularities
Cristi Stoica
DFT/IFIN-HH
Abstract:
In the past, I developed the extension of semi-Riemannian geometry for a class of degenerate metrics. Then I applied this theory to big bang and black hole singularities in General Relativity. The Einstein equation can be rewritten so that outside the singularities is equivalent to the standard version, but in addition can be extended at singularities [3]. But it is also important to see what happens with other fields at singularities, in particular the electromagnetic field and other gauge fields, and also to scalar and spinorial fields. I present some advances I've made recently in this direction, and what plans I have for the future. The Maxwell and Yang-Mills equations break down at singularities in their usual form, because either the metric is singular, or its inverse, and both are needed to define the differential operators involved. However, I will show that there is a way to reformulate them, which can be extended at singularities, while still remaining equivalent to the standard one outside the singularities [7]. I will present some perspectives of development in this direction. After studying the classical fields at singularities, the next logical step is to see what happens to quantum fields, hopefully including gravity. A recent article I published in 2014 contains some implications of singularities to a method of regularization in Quantum Gravity, based on dimensional reduction [2]. I intend to develop some of the ideas started there, and to find new implications.
References:
2014 or newer:
[1] C. Stoica, On singular semi-Riemannian manifolds, Int. J. Geom. Methods Mod. Phys., 0(0):1450041, March 2014.
[2] C. Stoica, Metric dimensional reduction at singularities with implications to Quantum Gravity, Annals of Physics 347C (2014), pp. 74-91.
[3] C. Stoica, Einstein Equation at singularities, Cent. Eur. J. Phys., 12 (2014), 123-131.
[4] C. Stoica, The geometry of black hole singularities, Advances in High Energy Physics, vol. 2014 (2014), article ID 907518.
[5] C. Stoica, Cartan's structural equations for degenerate metric, Balkan J. Geom. Appl., vol. 19, no. 2, (2014), p. 118-126.
[6] C. Stoica, The Tao of It and Bit, chapter in the volume "It from Bit or Bit from It?" published by Springer, to appear in March 2015.
[7] C. Stoica, Gauge theory at singularities, conference talk at "X-th International Conference on Finsler Extensions of Relativity Theory, FERT 2014, Brasov, Romania", arXiv:1408.3812.
[8] C. Stoica, The geometry of singularities and the black hole information paradox, conference talk at "Spacetime - Matter - Quantum Mechanics, Seventh International Workshop DICE2014".
Older than 2014:
[9] C. Stoica On the Weyl Curvature Hypothesis, Annals of Physics, 338:186-194, November 2013.
[10] Big Bang singularity in the FLRW spacetime, cinference talk at "The VII-th International Conference of Differential Geometry and Dynamical Systems, DGDS 2013, Bucuresti, Romania."
[11] C. Stoica Kerr-Newman solutions with analytic singularity and no closed timelike curves, To appear in U.P.B. Sci. Bull., Series A.
[12] C. Stoica Schwarzschild Singularity is semi-Regularizable, Eur. Phys. J. Plus, 127(83):1-8, 2012.
[13] C. Stoica Beyond the Friedmann-Lemaitre-Robertson-Walker big bang singularity, Commun. Theor. Phys., 58(4):613-616, March 2012.
[17] C. Stoica Spacetimes with singularities, An. St. Univ. Ovidius Constanta, 20(2):213-238, July 2012.
[15] C. Stoica Analytic Reissner-Nordstrom singularity, Physica Scripta, 85(5):055004, 2012.
Modified Drukarev Method in Quantum Scattering
N. Grama
DFT/IFIN-HH
Abstract:
The Drukarev method is modified and applied to quantum scattering. In the Drukarev method the radial solution f l (r) of the Lippman-Schwinger equation is replaced by the function R l (r) = D l (k) f l (r). In this way the radial Lippman-Scwinger integral equation for f l (r) is replaced by the Volterra integral equation for R l (r). In the present work a new condition is introduced in order to determine the constant D l (k). The modified Drukarev method alows separation of the poles of the partial scattering amplitude and obtaining the Liouville-Neumann series of the radial solution of the scattering problem that is convergent in the whole k-plane. The modified Drukarev method is applied to some central potentials. It is shown that the use of the radiation condition for short-range potential gives wrong results in the case of long range potential. The associated errors are analysed.
Weyl on Space and Geometry
Dr. Iulian Toader
Universitatea Bucuresti, Facultatea de Filosofie
Abstract:
In this talk, I discuss Hermann Weyl's revision of general relativity and his solution to the problem of space. With regard to the former, I focus critically on his argument for the introduction of a purely infinitesimal geometry. With regard to the latter, I explain the significance of his distinction between the nature and orientation of the metric. I close with some general remarks on the relationship between (Weyl's) physics and (his) philosophy.
