Mass splittings of nuclear isotopes in chiral soliton approach

The differences of the masses of nuclear isotopes with atomic numbers between \~10 and ~30 can be described within the chiral soliton approach in satisfactory agreement with data. Rescaling of the model is necessary for this purpose - decrease of the Skyrme constant by about 30%, providing the "nuclear variant" of the model. The asymmetric term in Weizsaecker-Bethe- Bacher mass formula for nuclei can be obtained as the isospin dependent quantum correction to the nucleus energy. Some predictions for the binding energies of neutron rich nuclides are made in this way, from, e.g. Be-16 and B-19 to Ne-31 and Na-32. Neutron rich nuclides with high values of isospin are unstable relative to strong interactions. The SK4 (Skyrme) variant of the model, as well as SK6 variant (6-th order term in chiral derivatives in the lagrangian as solitons stabilizer) are considered, and the rational map approximation is used to describe multiskyrmions.Comment: 16 pages, 10 tables, 2 figures. Figures are added and few misprints are removed. Submitted to Phys. Atom. Nucl. (Yad. Fiz.

Examples of the Zeroth Theorem of the History of Physics

The zeroth theorem of the history of science (enunciated by E. P. Fischer) and widely known in the mathematics community as Arnol'd's Principle (decreed by M. V. Berry), states that a discovery (rule, regularity, insight) named after someone (often) did not originate with that person. I present five examples from physics: the Lorentz condition defining the Lorentz gauge of the electromagnetic potentials; the Dirac delta function (x); the Schumann resonances of the earth-ionosphere cavity; the Weizsacker-Williams method of virtual quanta; the BMT equation of spin dynamics. I give illustrated thumbnail sketches of both the true and reputed discoverers and quote from their "discovery" publications.Comment: 36 pages, 8 figures. Small revisions, added material and references - Arnol'd's law, Emil Wiechert. Submitted to Am. J. Phy

J/psi plus prompt-photon associated production in two-photon collisions at next-to-leading order

We calculate the cross section of J/psi plus prompt-photon inclusive production in gamma gamma collisions at next-to-leading order within the factorization formalism of nonrelativistic quantum chromodynamics (NRQCD) focusing on direct photoproduction. Apart from direct J/psi production, we also include the feed-down from directly-produced chi_{cJ} and psi' mesons. We discuss the analytical calculation, in particular the treatment of the various types of singularities and the NRQCD operator renormalization, in some detail. We present theoretical predictions for the future e^+e^- linear collider TESLA, taking into account both brems- and beamstrahlung.Comment: 31 pages, 9 figure

DC and AC Josephson effects with superfluid Fermi atoms across a Feshbach resonance

We show that both DC and AC Josephson effects with superfluid Fermi atoms in the BCS-BEC crossover can be described at zero temperature by a nonlinear Schrodinger equation (NLSE). By comparing our NLSE with mean-field extended BCS calculations, we find that the NLSE is reliable in the BEC side of the crossover up to the unitarity limit. The NLSE can be used for weakly-linked atomic superfluids also in the BCS side of the crossover by taking the tunneling energy as a phenomenological parameter.Comment: 8 pages, 4 figures, presented at the Scientific Seminar on Physics of Cold Trapped Atoms, 17th International Laser Physics Workshop (Trondheim, June 30 - July 4, 2008

Financial Transaction Tax: Small is Beautiful

The case for taxing financial transactions merely to raise more revenues from the financial sector is not particularly strong. Better alternatives to tax the financial sector are likely to be available. However, a tax on financial transactions could be justified in order to limit socially undesirable transactions when more direct means of doing so are unavailable for political or practical reasons. Some financial transactions are indeed likely to do more harm than good, especially when they contribute to the systemic risk of the financial system. However, such a financial transaction tax should be very small, much smaller than the negative externalities in question, because it is a blunt instrument that also drives out socially useful transactions. There is a case for taxing over-the-counter derivative transactions at a somewhat higher rate than exchange-based derivative transactions. More targeted remedies to drive out socially undesirable transactions should be sought in parallel, which would allow, after their implementation, to reduce or even phase out financialtransaction taxes

Virtual Photon Strucutre Functions and the Parton Content of the Electron

We point out that in processes involving the parton content of the photon the usual effective photon approximation should be modified. The reason is that the parton content of virtual photons is logarithmically suppressed compared to real photons. We describe this suppression using several simple, physically motivated ans\"atze. Although the parton content of the electron in general no longer factorizes into an electron flux function and a photon structure function, it can still be expressed as a single integral. Numerical examples are given for the \eplem\ collider TRISTAN as well as the $ep$ collider HERA.Comment: 16 pages and 3 figures (available from DREES@WSICPHEN as topdraw or PS files); LaTeX with equation.sty; MAD/PH/819, BU 94-0

Turbulent Control of the Star Formation Efficiency

Supersonic turbulence plays a dual role in molecular clouds: On one hand, it contributes to the global support of the clouds, while on the other it promotes the formation of small-scale density fluctuations, identifiable with clumps and cores. Within these, the local Jeans length \Ljc is reduced, and collapse ensues if \Ljc becomes smaller than the clump size and the magnetic support is insufficient (i.e., the core is ``magnetically supercritical''); otherwise, the clumps do not collapse and are expected to re-expand and disperse on a few free-fall times. This case may correspond to a fraction of the observed starless cores. The star formation efficiency (SFE, the fraction of the cloud's mass that ends up in collapsed objects) is smaller than unity because the mass contained in collapsing clumps is smaller than the total cloud mass. However, in non-magnetic numerical simulations with realistic Mach numbers and turbulence driving scales, the SFE is still larger than observational estimates. The presence of a magnetic field, even if magnetically supercritical, appears to further reduce the SFE, but by reducing the probability of core formation rather than by delaying the collapse of individual cores, as was formerly thought. Precise quantification of these effects as a function of global cloud parameters is still needed.Comment: Invited review for the conference "IMF@50: the Initial Mass Function 50 Years Later", to be published by Kluwer Academic Publishers, eds. E. Corbelli, F. Palla, and H. Zinnecke

SUSY signals at HERA in the no-scale flipped SU(5) supergravity model

Sparticle production and detection at HERA are studied within the recently proposed no-scale flipped $SU(5)$ supergravity model. Among the various reaction channels that could lead to sparticle production at HERA, only the following are within its limit of sensitivity in this model: $e^-p\to \tilde e^-_{L,R}\chi^0_i+X, \tilde \nu_e\chi^-_1+X$, where $\chi^0_i(i=1,2)$ are the two lightest neutralinos and $\chi^-_1$ is the lightest chargino. We study the elastic and deep-inelastic contributions to the cross sections using the Weizs\"acker-Williams approximation. We find that the most promising supersymmetric production channel is right-handed selectron ($\tilde e_{R}$) plus first neutralino ($\chi^0_1$), with one hard electron and missing energy signature. The $\tilde\nu_e\chi^-_1$ channel leads to comparable rates but also allows jet final states. A right-handedly polarized electron beam at HERA would shut off the latter channel and allow preferentially the former one. With an integrated luminosity of {\cal L}=100\ipb, HERA can extend the present LEPI lower bounds on $m_{\tilde e_R}, m_{\tilde\nu_e},m_{\chi^0_1}$ by \approx25\GeV, while {\cal L}=1000\ipb will make HERA competitive with LEPII. We also show that the Leading Proton Spectrometer (LPS) at HERA is an excellent supersymmetry detector which can provide indirect information about the sparticle masses by measuring the leading proton longitudinal momentum distribution.Comment: 11 pages, 8 figures (available upon request as uuencoded file or separate ps files), tex (harvmac) CTP-TAMU-15/93, CERN/LAA/93-1

Stochastic motion of test particle implies that G varies with time

The aim of this letter is to propose a new description to the time varying gravitational constant problem, which naturally implements the Dirac's large numbers hypothesis in a new proposed holographic scenario for the origin of gravity as an entropic force. We survey the effect of the Stochastic motion of the test particle in Verlinde's scenario for gravity\cite{Verlinde}. Firstly we show that we must get the equipartition values for $t\rightarrow\infty$ which leads to the usual Newtonian gravitational constant. Secondly,the stochastic (Brownian) essence of the motion of the test particle, modifies the Newton's 2'nd law. The direct result is that the Newtonian constant has been time dependence in resemblance as \cite{Running}.Comment: Accepted in International Journal of Theoretical Physic

Evidence for Colour-Octet Mechanism from CERN LEP2 gamma gamma -> J/psi + X Data

We present theoretical predictions for the transverse-momentum distribution of J/psi mesons promptly produced in gamma gamma collisions within the factorization formalism of nonrelativistic quantum chromodynamics, including the contributions from both direct and resolved photons, and we perform a conservative error analysis. The fraction of J/psi mesons from decays of bottom-flavoured hadrons is estimated to be negligibly small. New data taken by the DELPHI Collaboration at LEP2 nicely confirm these predictions, while they disfavour those obtained within the traditional colour-singlet model.Comment: 11 pages (Latex), 3 figures (Postscript); updated experimental data included, references added, accepted for publication in Phys. Rev. Let