May 2001 arXiv papers — page 10

I. Jack, D. R. T. Jones

We establish the ultra-violet finiteness of various classes of noncommutative gauge theories.

S. H. Hansen, G. Mangano, A. Melchiorri, G. Miele

We perform a likelihood analysis of the recent results on the anisotropy of Cosmic Microwave Background Radiation from the BOOMERanG and DASI experiments to show that they single out an effective number of neutrinos in good agreement with standard Big Bang Nucleosynthesis. We also consider degenerate Big Bang Nucleosynthesis to provide new bounds on effectiv

P. Kratzer, E. Penev, M. Scheffler

We demonstrate how first-principles calculations using density-functional theory (DFT) can be applied to gain insight into the molecular processes that rule the physics of materials processing. Specifically, we study the molecular beam epitaxy (MBE) of arsenic compound semiconductors. For homoepitaxy of GaAs on GaAs(001), a growth model is presented that bui

Matthias Schneider, Dieter Lipp, Alexander Gladun, Peter Zahn

A polycrystalline sample of the MgB_2 superconductor was investigated by measurements of the electrical resistivity, the thermopower and the thermal conductivity in the temperature range between 1.8K and 300K in zero magnetic field. The electrical resistivity shows a superconducting transition at T_c=38.7K and, similarly to borocarbides, a T^2.4 behaviour up

S. Khochfar, A. Burkert

We use semi-analytical modelling of galaxy formation to study the redshift evolution of the galaxy merger fractions and merger ratesin Lambda CDM and quintessence (QCDM) cosmologies, their dependence on physical parameters as the environment, the merger timescale, the way major mergers are defined, and the minimum mass of objects taken into account. We find

P. Braun-Munzinger, D. Magestro, K. Redlich, J. Stachel

We present an analysis of particle production yields measured in central Au-Au collisions at RHIC in the framework of the statistical thermal model. We demonstrate that the model extrapolated from previous analyses at SPS and AGS energy is in good agreement with the available experimental data at $\sqrt s=130$ GeV implying a high degree of chemical equilibra

A. G. Akeroyd, S. Baek

We show that large ($> 100$ GeV) mass splittings between the charged Higgs boson ($H^\pm$) and the neutral Higgs bosons ($H^0$ and $A^0$) are possible in the Minimal Supersymmetric Standard Model (MSSM). Such splittings occur when the $μ$ parameter is considerably larger than the common SUSY scale, $M_{SUSY}$, and have significant consequences for MSSM Higgs

F. S. Navarra, M. Nielsen, R. S. Marques de Carvalho, G. Krein

The $J/ψπ\to \bar{D} D^*, \bar{D} D$, ${\bar D}^* D^*$ and ${\bar D} D^*$ cross sections as a function of $\sqrt{s}$ are evaluated in a QCD sum rule calculation. We study the Borel sum rule for the four point function involving pseudoscalar and vector meson currents, up to dimension four in the operator product expansion. We find that our results are smaller

A. Steinacker, Yu. A. Shchekinov

Within a framework of 2D MHD simulations, we explore the dynamical regimes initi ated by a supernova explosion in a magnetized stratified ISM. We concentrate on the formation of large scale magnetic structures and outflows connected with the Parker instability. For the sake of simplicity we show only models with a fixed explosion energy corresponding to a si

Takeshi Fukuda, Kazuo Hosomichi

We calculate the three-point functions in the sine-Liouville theory explicitly. The same calculation was done in the (unpublished) work of Fateev, Zamolodchikov and Zamolodchikov to check the conjectured duality between the sine-Liouville and the SL(2,R)/U(1) coset CFTs. The evaluation of correlators boils down to that of a free-field theory with a certain n

C. Berthod, B. Giovannini

We calculated the electronic structure of a vortex in a pseudogapped superconductor within a model featuring strong correlations. With increasing strength of the correlations, the BCS core states are suppressed and the spectra in and outside the core become similar. If the correlations are short-range, we find new core states in agreement with the observatio

J. Penarrocha, K. Schilcher

The mass of the charm quark is analyzed in the context of QCD finite energy sum rules using recent BESII e+e- annihilation data and a large momentum expansion of the QCD correlator which incorporates terms to order (alpha_s)^2 (m_c^2/q^2)^6. Using various versions of duality, we obtain the consistent result m_c(m_c)=(1.37 +- 0.09)GeV. Our result is quite ind

Bodo Geyer, Petr Lavrov, Armen Nersessian

We propose an extended BRST invariant Lagrangian quantization scheme of general gauge theories based on an explicit realization of the modified triplectic algebra that was announced in our previous investigation (hep-th/0104189). The algebra includes, besides the odd operators $V^a$ appearing in the triplectic formalism, also the odd operators $U^a$ introduc

Hui Hu, Guang-Ming Zhang, Lu Yu

We study the Kondo screening effect generated by a single-electron transistor or quantum dot embedded in a small metallic ring. When the ring circumference $L$ becomes comparable to the fundamental length scale $ξ_K^0=\hbar \upsilon _F/T_K^0$ associated with the {\it bulk} Kondo tempe the Kondo resonance is strongly affected, depending on the total number of

J. Lehr, U. Mosel

We analyze the effects of an in-medium broadening of nucleon resonances on the exclusive photoproduction of mesons on nuclei as well as on the total photoabsorption cross sections in a transport calculation. We show that the resonance widths observed in semi-inclusive photoproduction on nuclei are insensitive to an in-medium broadening of nucleon resonances.

M. Brack, M. Mehta, K. Tanaka

We investigate cascades of isochronous pitchfork bifurcations of straight-line librating orbits in some two-dimensional Hamiltonian systems with mixed phase space. We show that the new bifurcated orbits, which are responsible for the onset of chaos, are given analytically by the periodic solutions of the Lamé equation as classified in 1940 by Ince. In Hamilt

Rong-Gen Cai, Yuan-Zhong Zhang

We consider a class of domain-wall black hole solutions in the dilaton gravity with a Liouville-type dilaton potential. Using the surface counterterm approach we calculate the stress-energy tensor of quantum field theory (QFT) corresponding to the domain-wall black hole in the domain-wall/QFT correspondence. A brane universe is investigated in the domain-wal

Ryuichiro Kitano, Nobuchika Okada

We propose a new mechanism towards the solution to the doublet-triplet Higgs mass splitting problem in the supersymmetric grand unified theory. Our model is based on the gauge group $SU(5)_H \times SU(5)_{GUT}$, where $SU(5)_H$ and $SU(5)_{GUT}$ are a new strong gauge interaction and the ordinary grand unified gauge group, respectively. The doublet-triplet H

Diederik Aerts

We formulate a paradox in relation to the description of a joint entity consisting of two subentities by standard quantum mechanics. We put forward a proposal for a possible solution, entailing the interpretation of density states as pure states. We explain where the inspiration for this proposal comes from and how its validity can be tested experimentally.

Lu-Ming Duan, Mikhail Lukin, Ignacio Cirac, Peter Zoller

Quantum communication holds a promise for absolutely secure transmission of secret messages and faithful transfer of unknown quantum states. Photonic channels appear to be very attractive for physical implementation of quantum communication. However, due to losses and decoherence in the channel, the communication fidelity decreases exponentially with the cha

Oliver Rudolph

We obtain a mathematically simple characterization of all functionals coinciding with the von Neumann reduced entropy on pure states based on the Khinchin-Faddeev axiomatization of Shannon entropy and give a physical interpretation of the axioms in terms of entanglement.

Kazuyuki Fujii

In the first half we show an interesting relation between coherent states and the Bell states in the case of spin 1/2, which was suggested by Fivel. In the latter half we treat generalized coherent states and try to generalize this relation to get several generalized Bell states. Our method is based on a geometry and our task may give a hint to open a deep r

Anthony D. Klemm, Michel Fabre de la Ripelle, Sigurd Yves Larsen

The hyperspherical harmonics (HH) provide a complete basis for the expansion of atomic wave functions, but even for two particles the number of harmonics for a given order is not trivial and, as the number of electrons increases, this degeneracy becomes absolutely prohibitive. We modify the method by selecting a subset of the basis that, we feel, will yield

A. Vardi, M. Shapiro

The possibility of accelerating molecular reactions by lasers has attracted considerable theoretical and experimental interest. A particular example of laser-modified reaction dynamics is laser catalysis, a process in which the tunneling through a potential barrier is enhanced by transient excitation to a bound electronic state. We have performed detailed ca

Sigurd Yves Larsen

First, we show that, if there are no bound states, we can express the q.m. third cluster - involving 3 and fewer particles in Statistical Mechanics - as a formula involving adiabatic eigenphase shifts. This is for Boltzmann statistics. From this q.m. formulation, in the case of purely repulsive forces, we recover, as h goes to 0, the classical expressions fo

Florin Despa, R. Stephen Berry

We explore the way free particles produced by dissociating ``particle-hole pairs'' on a surface-melted cluster can be transferred to a second, nearby surface-melted cluster. This mass transport is based on an inter-cluster direct transfer mechanism of the particles. We found that in this particular case one cluster may grow at the expense of another,

J. R. Anglin, A. Vardi

We study the dynamics of a two-mode Bose-Einstein condensate in the vicinity of a mean-field dynamical instability. Convergence to mean-field theory (MFT), with increasing total number of particles $N$, is shown to be logarithmically slow. Using a density matrix formalism rather than the conventional wavefunction methods, we derive an improved set of equatio

Alexander V. Shchagin

It is shown that the diffraction on a polycrystal can be used for investigation and diagnostics of X-ray radiation emitted in a forward direction by relativistic charged particles moving in crystalline or other targets or fields. Methods for measuring radiation spectral density, divergence, and linear polarization at any requisite energy from a few units to

Denis V. Juriev

Some conceptual aspects of the quantum string field psychophysics are clarified.

S. R. Mokhtar, M. Anguiano, G. Co', A. M. Lallena

One-nucleon emission electron scattering experiments are studied with a model that considers short--range correlations up to the first order in the number of correlation lines. The proper normalization of the many-body wave functions requires the evaluation of two- and three-point diagrams, the last ones usually neglected in the literature. When all these di

N. Kaiser, S. Fritsch, W. Weise

We calculate the equation of state of isospin-symmetric nuclear matter in the three-loop approximation of chiral perturbation theory. The contributions to the energy per particle $\bar E(k_f)$ from one- and two-pion exchange diagrams are ordered in powers of the Fermi momentum $k_f$ (modulo functions of $k_f /m_π$). It is demonstrated that, already at order

A. I. L'vov

Radiative transitions gamma + Delta(1232) -> N^* are discussed in the nonrelativistic quark model with spin-orbit corrections for the 70-plet L^P=1^- nucleon resonances N^*. The reaction gamma + N -> gamma + Delta is considered as a tool to measure some of these transitions. A particular sensitivity to photoexcitations of S_{11}(1535), D_{13}(1700), and D_{1

L. Faybusovich, M. Gekhtman

We give a solution to the inverse moment problem for a certain class of Hessenberg and symmetric matrices related to integrable lattices of Toda type.

Z. Kaufmann, H. Lustfeld

It is shown that in transient chaos there is no direct relation between averages in a continuos time dynamical system (flow) and averages using the analogous discrete system defined by the corresponding Poincare map. In contrast to permanent chaos, results obtained from the Poincare map can even be qualitatively incorrect. The reason is that the return time

John Wyller, Wieslaw Krolikowski, Ole Bang, Jens Juul Rasmussen

The modulational instability (MI) of plane waves in nonlocal Kerr media is studied for a general, localized, response function. It is shown that there always exists a finite number of well-separated MI gain bands, with each of them characterised by a unique maximal growth rate. This is a general property and is demonstrated here for the Gaussian, exponential

Gabriele Vezzosi, Angelo Vistoli

We prove a decomposition theorem for the equivariant K-theory of actions of affine group schemes G of finite type over a field on regular separated noetherian algebraic spaces, under the hypothesis that the actions have finite geometric stabilizers and satisfy a rationality condition together with a technical condition which holds e.g. for G abelian or smoot

Nik Weaver

Akemann and Anderson made a conjecture about ``paving'' projections in finite dimensional matrix algebras which, if true, would settle the well-known Kadison-Singer problem. We falsify their conjecture by an explicit seqence of counterexamples.

A. Tsemo

We study affine maps between affine manifolds. Even when the fibers are compact and diffeomorphic, two of them can inherit different affine structures from the source space. This leads to a fixed linear holonomy deformation theory of the affine structure of an affine manifold. We found various conditions which make the fibers to be affinely isomorphic. We al

Yuri G. Rykov

It is studied the Cauchy problem for the equations of Burgers' type but with bounded dissipation flux. Such equations degenerate to hyperbolic ones as the velocity gradient tends to infinity. Thus the discontinuous solutions are permitted. In the paper the definition of the generalized solution is given and the existence theorem is established in the cla

V. Kharlamov, Vik. S. Kulikov

We prove that there is an infinite sequence of pairs of plane cuspidal curves $C_{m,1}$ and $C_{m,2}$, such that the pairs $(\Bbb CP^2, C_{m,1})$ and $(\Bbb CP^2, C_{m,2})$ are diffeomorphic, but $C_{m,1}$ and $C_{m,2}$ have non-equivalent braid monodromy factorizations. These curves give rise to the negative solutions of "Dif=Def" and "Dif=Iso&#

Ben Craps, Per Kraus, Finn Larsen

We study loop corrections in boundary string field theory (BSFT). After commenting on problems with quantizing the tree level BSFT as an ordinary field theory, we discuss the tree level coupling to closed strings and define the loop corrections via factorization in the closed string channel. This description is weakly coupled in the vicinity of the closed st

Chun-Ming Chiang, Choon-Lin Ho

The Dirac equation for an electron in two spatial dimensions in the Coulomb and homogeneous magnetic fields is an example of the so-called quasi-exactly solvable models. The solvable parts of its spectrum was previously solved from the recursion relations. In this work we present a purely algebraic solution based on the Bethe ansatz equations. It is realised

O. Oliveira

The problem of identifying the dynamical degrees of freedom for SU(2) gauge theories is discussed. After studying SU(N) theories, it is shown that classical pure SU(2) gauge theory is equivalent to an abelian theory. Finally, we prove that the Maximal Abelian Gauge correctly identifies the abelian degrees of freedom of the SU(2) theory.

P. M. Saffin

It is shown how magnetic fluxbrane, Fp-brane, solutions are related to electric black p-branes by analytic continuation. Viewing the transverse space of branes as a warped cone, one finds that the cone base of the p-brane becomes the world-volume of the F(D-p-3)-brane and the world volume of the p-brane becomes the cone base of the F(D-p-3)-brane. An explici

Bruno Carneiro da Cunha

The encoding of an inflating patch of space-time in terms of a dual theory is discussed. Following Bousso's interpretation of the holographic principle, we find that those are generically described not by states in the dual theory but by density matrices. We try to implement this idea on simple deformations of the AdS/CFT examples, and an argument is giv

P. S. Howe, P. C. West

A discussion of the AdS/CFT correspondence in IIB is given in a superspace context. The main emphasis is on the properties of SCFT correlators on the boundary which are studied using harmonic superspace techniques. These techniques provide the easiest way of implementing the superconformal Ward identities. The Ward identities, together with analyticity, can

Suresh Govindarajan, T. Jayaraman

We review some recent results on D-branes on Calabi-Yau (CY) manifolds. We show the existence of structures (helices and quivers) which enable one to make statements about large families of D-branes in various phases of the Gauged Linear Sigma Model (GLSM) associated with the CY manifold. A comparison of the quivers of two phases leads to the prediction that

A. G. Abanov, P. B. Wiegmann

Solitons of a nonlinear field interacting with fermions often acquire a fermionic number or an electric charge if fermions carry a charge. We show how the same mechanism (chiral anomaly) gives solitons statistical and rotational properties of fermions. These properties are encoded in a geometrical phase, i.e., an imaginary part of a Euclidian action for a no

Justin Khoury, Burt A. Ovrut, Paul J. Steinhardt, Neil Turok

We respond to the criticisms by Kallosh, Kofman and Linde concerning our proposal of the ekpyrotic universe scenario. We point out a number of errors in their considerations and argue that, at this stage, the ekpyrotic model is a possible alternative to inflationary cosmology as a description of the very early universe.

Davide Fioravanti

In the framework of the Sine-Gordon (SG) theory we will present the construction of a dynamical Virasoro symmetry which has nothing to do with the space-time Virasoro symmetry of 2D CFT. Although, it is non-local in the SG field theory, nevertheless it gives rise to a local action on specific N-soliton solution variables. These {\it analytic} variables posse

O. J. P. Eboli, J. K. Mizukoshi

We analyze the potential of the e+e- Linear Colliders, operating in the e-gamma and gamma-gamma modes, to probe anomalous quartic vector--boson interactions through the multiple production of W's and Z's. We examine all $SU(2)_L \otimes U(1)_Y$ chiral operators of order p^4 that lead to new four--gauge--boson interactions but do not alter trilinear v

Thomas W. Kephart, Qaisar Shafi

The embedding in SU(4)xSU(3)xSU(3) of the well studied gauge groups SU(4)xSU(2)xSU(2) and SU(3)xSU(3)xSU(3) naturally leads to family unification as opposed to simple family replication. An inescapable consequence is the predicted existence of (exotic)color singlet states that carry fractional electric charge. The corresponding magnetic monopoles carry multi

S. Digal, P. Petreczky, H. Satz

Recent lattice studies of string breaking in QCD with dynamical quarks determine the in-medium temperature dependence of the heavy quark potential. Comparing this to the binding energies of different quarkonium states, we check if these can decay into open charm/beauty in a confined hadronic medium. Our studies indicate in particular that the chi_c and the p

C. A. Salgado

Coherence effects are important in the description of collisions with extended objects as nuclei. At fixed target energies and small x_F, the coherence length of the fluctuation containing the $c\bar c$ is small and the usual nuclear absorption model is valid. However, at higher energies and/or x_F the nucleus is seen as a whole by the fluctuation. In this c

Nigel K. Watson

Precise measurements of the mass and width of the W boson are carried out in e+e- collisions at LEP, by kinematic reconstruction of the invariant mass distributions of WW->qqlv and WW->qqqq candidate events. The most recent combination of such results from ALEPH, DELPHI, L3 and OPAL uses approximately 82% of the final LEP2 integrated luminosity and is prelim

S. Groote, J. G. Körner, A. A. Pivovarov

We discuss the choice of weight functions for the moments of the spectral density for two-point correlators of hadronic currents over a finite energy interval. Of phenomenological relevance is an analysis of the spectra of tau lepton decay on the energy interval [0,M_tau] and the low-energy hadron production in e+ e- annihilation. General arguments are given

J. M. Campbell

We summarize recent progress in next-to-leading order QCD calculations made using the Monte Carlo MCFM. In particular, we focus on the calculations of p anti-p -> W b-bbar, Z b-bbar and highlight the significant corrections to background estimates for Higgs searches in the channels WH and ZH at the Tevatron. We also report on the current progress of, and str

L. Ya. Glozman

It has recently been suggested that the observed structure of parity doublets, seen in the spectrum of highly excited baryons, may be due to the effective restoration of chiral symmetry for these states. This chiral symmetry restoration high in the spectrum is consistent with the concept of quark-hadron duality. Moreover, if QCD dynamics implies the linear R

V. A. Khoze

We quantify the rate and the signal-to-background ratio for Higgs --> b anti-b detection in double-diffractive events at the Tevatron and the LHC. The signal is predicted to be very small at the Tevatron, but observable at the LHC. We show that the double-diffractive dijet production may serve as a unique gluon factory. This process can be used also as a Pom

Daijiro Suematsu

We propose a simple model of the neutrino mass matrix which can explain the solar and atmospheric neutrino problems in a 3($ν_L + ν_R$) framework. Assuming that only two right-handed neutrinos are heavy and a Dirac mass matrix has a special texture, we construct a model with four light neutrinos. The favorable structure of flavor mixings and mass eigenvalues

A. Abada, Ph. Boucaud, G. Herdoiza, J. P. Leroy

We present the first attempt of a new method to compute the pion light-cone wave function (LCWF) on the lattice. We compute the matrix element between the pion and the vacuum of a non-local operator: the propagator of a ``scalar quark'' (named for short "squark"). A theoretical analysis shows that for some kinematical conditions (energetic pi

Kaoru Okano

Within the closed-time-path formalism of nonequilibrium QCD, we derive a Slavnov-Taylor (ST) identity for the gluon polarization tensor. The ST identity takes the same form both in Coulomb and covariant gauges. Application to quasi-uniform quark-gluon plasma (QGP) near equilibrium or nonequilibrium quasistationary QGP is made.

Matthias Neubert, Thomas Becher

We reduce the perturbative uncertainty in the determination of |V_{ub}| from inclusive semileptonic B decays by calculating the rate of B -> X_u l nu events with dilepton invariant mass q^2>(M_B-M_D)^2 at subleading order in the hybrid expansion, and to next-to-leading order in renormalization-group improved perturbation theory. We also resum logarithmic cor

A. Bodek, T. Adams, A. Alton, C. G. Arroyo

We report on the extraction of R=sigam_L/sigma_T from CCFR neutrino and antineutrino-Iron differential cross sections. R as measured in neutrno scattering is in agreement with $R$ as measured in muon and electron scattering. All data on R for Q2 > 1 GeV2 are in agreement with a NNLO QCD calculation which uses NNLO PDFs and includes target mass effects. We re

D. Karlen, H. Burkhardt

We discuss the possibility of a precision measurement of vacuum polarization in t-channel radiative Bhabha scattering at a high luminosity collider. For illustration, the achievable precision is estimated for the BaBar experiment at PEP-II and for the OPAL experiment at LEP.

T. Sloan

Recent measurements of Charm and Beauty production at HERA are described. The charm results are well described by NLO QCD calculations with a somewhat better description in the CCFM than in the DGLAP evolution schemes. However, the Beauty results in both photoproduction and in deep inelastic scattering (DIS) are poorly described by such calculations.

M. Musy

The study of charged and neutral boson vertices has been performed in different production channels at the LEP experiments. Decay rates and kinematic properties of these events are exploited to set constraints on the corresponding gauge couplings.

Aura Rosca

The four LEP experiments, ALEPH, DELPHI, L3 and OPAL, have searched for Higgs bosons predicted by a large number of extensions of the Standard Model. Flavor independent searches are presented for the h$^{0}$Z$^{0}$ process in which the h$^{0}$ decays hadronically. Search results are also presented for fermiophobic Higgs bosons, invisibly decaying Higgs boson

Nicolo de Groot

In this paper we present three updates to heavy flavour results from the SLD detector at SLAC. These results are preliminary, based on our full 1993-1998 dataset of 550 000 hadronic Z0 decays produced with an average electron polarisation of 73%. The new measurements are of the hadronic branching fractions into heavy quarks (Rb, Rc), the b quark asymmetry (A

A. Aganyants

The microscopic properties of the interactions of relativistic electrons were observed to alter when macro-conditions, such as the crystal vacuum, were changed. A qualitative explanation of the phenomenon is given.

J. A. Budagov, Y. A. Kulchitsky, M. V. Kuzmin, V. B. Vinogradov

This paper has been withdrawn by the authors.

Gene Kim, MyungHo Kim

After the completion of human genome sequence was anounced, it is evident that interpretation of DNA sequences is an immediate task to work on. For understanding their signals, improvement of present sequence analysis tools and developing new ones become necessary. Along this current trend, we attack one of the fundamental questions, which set of SNP(single

D. Lampakis, A. Tatsi, E. Liarokapis, G. Varelogiannis

We report micro-Raman measurements that reveal a low-energy soft mode at 16-19 meV in MgB_2 which becomes sharper in the superconducting state. With a boson spectrum based on this mode we reproduce, within Eliashberg theory, the T_c, the T-shape of the NMR relaxation rate as well as unusual dip-hump features in available tunneling data. We compare MgB_2 to c

F. J. Garcia-Vidal, J. M. Pitarke

Optical-absorption cross-sections and energy-loss spectra of aligned multishell carbon nanotubes are investigated, on the basis of photonic band-structure calculations. A local graphite-like dielectric tensor is assigned to every point of the tubules, and the effective transverse dielectric function of the composite is computed by solving Maxwell's equat

S. D. Gensemer, D. S. Jin

Relative motion in a two-component, trapped atomic gas provides a sensitive probe of interactions. By studying the lowest frequency excitations of a two spin-state gas confined in a magnetic trap, we have explored the transition from the collisionless to the hydrodynamic regime. As a function of collision rate, we observe frequency shifts as large as 6% as w

M. B. Hastings

We consider a general model of branch competition that automatically leads to a critical branching configuration. This model is inspired by the $4-η$ expansion of the dielectric breakdown model (DBM), but the mechanism of arriving at the critical point may be of relevance to other branching systems as well, such as fractures. The exact solution of this model

A. Vardi, V. A. Yurovsky, J. R. Anglin

We study the system of coupled atomic and molecular condensates within the two-mode model and beyond mean-field theory (MFT). Large amplitude atom-molecule coherent oscillations are shown to be damped by the rapid growth of fluctuations near the dynamically unstable molecular mode. This result contradicts earlier predictions about the recovery of atom-molecu

Prasenjit Sen, S. Ciraci, Inder P. Batra, C. H. Grein

At a given temperature, clean and adatom covered silicon surfaces usually exhibit well-defined reconstruction patterns. Our finite temperature ab-initio molecular dynamics calculations show that the tellurium covered Si(001) surface is an exception. Soft longitudinal modes of surface phonons due to the strongly anharmonic potential of the bridged tellurium a

I. L. Aleiner, Ya. M. Blanter

We revisit the problem of inelastic times governing the temperature behavior of the weak localization correction and mesoscopic fluctuations in one- and two-dimensional systems. It is shown that, for dephasing by the electron electron interaction, not only are those times identical but the scaling functions are also the same.

Stefano Luin, Vittorio Pellegrini, Fabio Beltram, Xavier Marcadet

Intersubband absorption in modulation-doped quantum wells is usually appropriately described as a collective excitation of the confined two-dimensional electron gas. At sufficiently low electron density and low temperatures, however, the in-plane disorder potential is able to damp the collective modes by mixing the intersubband charge-density excitation with

Eugene B. Kolomeisky, T. J. Newman, Joseph P. Straley, Xiaoya Qi

This is a published reply to the comment of Bhaduri and Sen, Physical Review Letters 86, 4708 (2001), cond-mat/0105385, on our original work, Physical Review Letters 85, 1146 (2000), cond-mat/0002282 . In this reply we point out that our continuum theory captures the correct physics of non-interacting fermions in one dimension. In contrast, the two proposed

A. J. Garcia-Adeva, D. L. Huber

A microscopic derivation of the classical Generalized Constant Coupling (GCC) model for geometrically frustrated magnets is presented. Starting from the classical Heisenberg Hamiltonian, the partition function for clusters with p = 2, 3, 4 ,...spins in the presence of the inhomogeneous symmetry breaking fields (SBF) created by spins outside the unit is calcu

Wei-Min Zhang

The square lattice structure of $CuO_2$ layers and the strongly correlated property of electrons indicate that the high $T_c$ superconductivity in cuprates can be described by a SO$_M$(5) coherent pairing state in which a SU$_M$(2)$\times$U$_C$(1) gauge symmetry is embedded. The spin and charge fluctuations that characterize the low energy magnetic excitatio

Pi-Gang Luan, Zhen Ye

The topology, the symmetry involving the shape of dielectric cylinders, and the lattice structure are among the most important ingredients in the architecture of photonic crystals. In this paper, we present a systematic derivation of the formulas which are needed in computing the photonic band structures of many commonly used two dimensional lattice structur

Massimo Rontani, Filippo Troiani, Ulrich Hohenester, Elisa Molinari

The many-body state of carriers confined in a quantum dot is controlled by the balance between their kinetic energy and their Coulomb correlation. In coupled quantum dots, both can be tuned by varying the inter-dot tunneling and interactions. Using a theoretical approach based on the diagonalization of the exact Hamiltonian, we show that transitions between

E. Alfinito, O. Romei, G. Vitiello

By resorting to some results in quantum field theories with spontaneous breakdown of symmetry we show that an explanation based on microscopic dynamics can be given of the fact that topological defect formation is observed during the process of non-equilibrium phase transitions characterized by a non-zero order parameter. We show that the Nambu-Goldstone par

K. Maiti, D. D. Sarma, M. J. Rozenberg, I. H. Inoue

We investigate the electronic structure of Ca$_{1-x}$Sr$_x$VO$_3$ using photoemission spectroscopy. Core level spectra establish an electronic phase separation at the surface, leading to distinctly different surface electronic structure compared to the bulk. Analysis of the photoemission spectra of this system allowed us to separate the surface and bulk cont

Bikash C. Gupta, Sang Bub Lee

The self-trapping transition due to a single and a dimer nonlinear impurity embedded in a Cayley tree is studied. In particular, the effect of a perfectly nonlinear Cayley tree is considered. A sharp self-trapping transition is observed in each case. It is also observed that the transition is much sharper compared to the case of one-dimensional lattices. For

M. Y. Choi, D. J. Thouless

A topological argument is constructed and applied to explain subharmonic mode locking in a system of coupled oscillators with inertia. Via a series of transformations, the system is shown to be described by a classical XY model with periodic bond angles, which is in turn mapped onto a tight-binding particle in a periodic gauge field. It is then revealed that

D. H. Santamore, M. C. Cross

The effect of phonon scattering by surface roughness on the thermal conductance in mesoscopic systems at low temperatures is calculated using full elasticity theory. The low frequency behavior of the scattering shows novel power law dependences arising from the unusual properties of the elastic modes. This leads to new predictions for the low temperature dep

Wada Tatsuaki, Saito Takeshi

Tsallis' non-extensive entropy $S_q$ enables us to treat both a power and exponential evolutions of underlying microscopic dynamics on equal footing by adjusting the variable entropic index $q$ to proper one $q^*$. We propose an alternative constraint of obtaining the proper entropic index $q^*$ that the non-additive conditional entropy becomes additive

J. H. Shim, B. I. Min

We have investigated electronic structures of a newly discovered antiperovskite superconductor MgCNi$_3$ and related compounds MgBNi$_3$ and MgNNi$_3$. In MgCNi$_3$, a peak of very narrow and high density of states is located just below $\rm E_F$, which corresponds to the $π^*$ antibonding state of Ni-3d and C-$2p$ but with the predominant Ni-3d character. T

Tarun Kanti Ghosh

We study a generalised Gross-Pitaevskii equation describing a d-dimensional harmonic trapped (with trap frequency $ω_{0}$) weakly interacting Bose gas with a non-linearity of order (2 k + 1) and scaling exponent (n) of the interaction potential. Using the time-dependent variational analysis, we explicitly show that for a particular combination of n, k and d,

R. Fux

(Abridged) The Galactic bar causes a characteristic splitting of the disc phase space into regular and chaotic orbit regions which is shown to play an important role in shaping the stellar velocity distribution in the Solar neighbourhood. A detailed orbital analysis within an analytical 2D rotating barred potential reveals that this splitting is mainly dicta

Richard H. Cyburt, Brian D. Fields, Keith A. Olive

Cosmic microwave background (CMB) determinations of the baryon-to-photon ratio $η\propto Ω_{\rm baryon} h^2$ will remove the last free parameter from (standard) big bang nucleosynthesis (BBN) calculations. This will make BBN a much sharper probe of early universe physics, for example, greatly refining the BBN measurement of the effective number of light neut

M. D. Shetrone, P. Cote, P. B. Stetson

Spectra for stars located redward of the fiducial red giant branches of the Ursa Minor and Draco dwarf spheroidal galaxies have been obtained with the Hobby-Eberly telescope and the Marcario Low Resolution Spectrometer. From a comparison of our radial velocities with those reported in previous medium-resolution studies, we find an average difference of 10 km

Swara Ravindranath, Luis C. Ho, Chien Y. Peng, Alexei V. Filippenko

We present surface photometry for the central regions of a sample of 33 early-type (E, S0, and S0/a) galaxies observed at 1.6 microns (H band) using the Hubble Space Telescope (HST). We employ a new technique of two-dimensional fitting to extract quantitative parameters for the bulge light distribution and nuclear point sources, taking into consideration the

Myungshin Im, S. M. Faber, Karl Gebhardt, David C. Koo

Several recent studies find that 10 - 50% of morphologically selected field early-type galaxies at redshifts z <= 1 have blue colors indicative of recent star formation. Such ``blue spheroids&#39;&#39;might be massive early-type galaxies with active star formation, perhaps induced by recent merger events. Alternatively, they could be starbursting, low-mass s

A. Del Popolo, M. Gambera

We study the joint effect of tidal torques and dynamical friction on the collapse of density peaks solving numerically the equations of motion of a shell of barionic matter falling into the central regions of a cluster of galaxies. We calculate the evolution of the expansion parameter, a(t), of the perturbation using a coefficient of dynamical friction eta_{

P. Vielva, R. B. Barreiro, M. P. Hobson, E. Martinez-Gonzalez

We present a maximum-entropy method (MEM) and `Mexican Hat&#39; wavelet (MHW) joint analysis to recover the different components of the microwave sky from simulated observations by the ESA Planck satellite in a small patch of the sky. This combined method allows one to improve the CMB, Sunyaev-Zel&#39;dovich and Galactic foregrounds separation achieved by th