December 2000 arXiv papers — page 15

N. D. Lambert, P. C. West

We discuss the interactions of Goldstone particles with solitonic states. We observe that, contrary to the familiar situation in the vacuum sector, the Goldstone particles can have non-derivative interactions with the solitons. This result is applied to brane physics and in particular leads to the possibility that neutrinos in brane world scenarios are Golds

M. Campostrini, M. Hasenbusch, A. Pelissetto, P. Rossi

Three-dimensional spin models of the Ising and XY universality classes are studied by a combination of high-temperature expansions and Monte Carlo simulations applied to improved Hamiltonians. The critical exponents and the critical equation of state are determined to very high precision.

T. Banks

I argue that isolated vacua of M-theory, cannot in any conventional way be said to live in the same theory as other disconnected parts of the moduli space. The usual field theoretic mechanisms, which allow an observer in one disconnected component of a moduli space to verify the existence of other components, fail. The failure is a consequence of robust prop

V. Pleitez

We show that direct CP violation in semi-leptonic and leptonic decays can occur in multi-Higgs doublet extensions of the electroweak standard model with flavor changing neutral currents. For pion and lepton decays these $CP$ violating effects cannot be constrained directly by experimental data since up to now the branching ratio of the decays $π^-$ and $μ^-$

James D. Wells

Supersymmetry phenomenology is an important component of particle physics today. I provide a definition of supersymmetry phenomenology, outline the scope of its activity, and argue its legitimacy. This essay derives from a presentation given at the 2000 SLAC Summer Institute.

F. Larios, M. A. Perez, G. Tavares-Velasco, J. J. Toscano

We list all the lowest dimension effective operators inducing off-shell trilinear neutral gauge boson couplings Z-Z-Photon, Z-Photon-Photon, and ZZZ within the effective Lagrangian approach, both in the linear and nonlinear realizations of the SU(2)_{L} X U(1)_Y gauge symmetry. In the linear scenario we find that these couplings can be generated only by dime

Maria Krawczyk

Development of concepts related to the photon and its high energy hadronic interaction is briefly reviewed. A photon considered as an ideal probe of hadron structure, paradoxically is also considered as an ideal target to test the perturbative QCD. The present status of the theoretical and experimental analysis of the structure functions for a virtual and re

Robert Harlander, William Kilgore

The calculation of the NNLO QCD corrections to the partonic process gg -> H is outlined. For the coupling of the Higgs boson to the gluons we use an effective Lagrangian in the limit of a heavy top quark. The focus is on the evaluation of the virtual two-loop corrections. It is shown that the leading pole terms are in agreement with the general formula by Ca

Cosmin Macesanu

We discuss the computation of QCD virtual corrections to the top production and decay process at linear colliders. The double pole approximation (DPA) is used, and we comment on similarities and differences between our results and results obtained in a similar framework for the QED corrections to the W pair production process at LEPII.

Marina Artuso

A piece of the Standard Model presently undergoing intense experimental scrutiny is the Cabibbo Kobayashi Maskawa matrix. Several different measurements are planned to enrich the spectrum of experimental constraints and thus provide one of the most stringent tests of Standard Model validity. The success of this program is closely related to theoretical progr

J. Ranft

Most hadronic event generators which can be used for simulating hadronic and nuclear collisions up to the highest energies are quite similar in their construction and in the underlying theoretical concepts. At energies, where data from accelerator and collider experiments are available the models agree rather well with each other and with the most important

H. Nunokawa

We discuss some possible influence of neutrino oscillations on physics of supernova mainly focusing on the observations of $\barν_e$, and present some analysis of SN1987A data in the light of three neutrino mixing scheme.

A. M. Gago, H. Nunokawa, R. Zukanovich Funchal

We have updated the analysis for the solution to the solar neutrino problem by the long-wavelength neutrino oscillations induced by a tiny breakdown of the weak equivalence principle of general relativity, and obtained a very good fit to all the solar neutrino data.

N. G. Antoniou, Y. F. Contoyiannis, F. K. Diakonos, A. I. Karanikas

A theoretical scheme which relates multiparticle states generated in ultrarelativistic nuclear collisions to a QCD phase transition is considered in the framework of the universality class provided by the 3-D Ising model. Two different evolution scenarios for the QGP system are examined. The statistical mechanics of the critical state is accounted for in ter

A. N. Sissakian, O. Yu. Shevchenko, V. N. Samoilov

In connection with the semi-inclusive polarized DIS, it is proposed to consider the first Melin moments $Δq$ of the polarized quark and antiquark densities, instead of the respective variables $δq(x)$, local in Bjorken x themselves. This gives rise to a very essential simplification of the next to leading order (NLO) QCD and, besides, allows one to use the r

K. -I. Izawa

We consider an effective field theory description of gravity coupled to a scalar field with volume-preserving diffeomorphism and Weyl invariances. The smallness of the cosmological constant is achieved when the potential of the scalar is extremely flat. This implies a possible relationship between the smallness and the quintessential sector of the cosmologic

Sadataka Furui, Hideo Nakajima

The colour confinement criterion proposed by Kugo and Ojima is tested in the lattice Landau gauge QCD simulation. The renormalization effects are studied by measuring the gluon propagator, ghost propagator, three gluon vertex and the ghost-antighost-gluon vertex.

DONUT Collaboration

The DONUT experiment has analyzed 203 neutrino interactions recorded in nuclear emulsion targets. A decay search has found evidence of four tau neutrino interactions with an estimated background of 0.34 events. This number is consistent with the Standard Model expectation.

D. V. Bandourin, V. F. Konoplianikov, N. B. Skachkov

"photon+Jet" events, based on the q~q-> g+photon and qg-> q+photon subprocesses, are proposed for jet energy scale setting and hadron calorimeter calibration at LHC energies. General features and selection criteria of "photon+Jet" events that would provide a good photon Pt - jet Pt balance are described. CMS detector geometry is taken as the

V. B. Bezerra, R. M. Teixeira Filho, G. Grebot, M. E. X. Guimaraes

We study the vacuum polarization effect in the spacetime generated by a magnetic flux cosmic string in the framework of a scalar-tensor gravity. The vacuum expectation values of the energy-momentum tensor of a conformally coupled scalar field are calculated. The dilaton's contribution to the vacuum polarization effect is shown explicitly.

Giovanni Amelino-Camelia

Quantum mechanics is now 100 years old and still going strong. Combining general relativity with quantum mechanics is the last hurdle to be overcome in the "quantum revolution".

Narayan Banerjee, Diego Pavon

It is argued that the Brans-Dicke theory may explain the present accelerated expansion of the universe without resorting to a cosmological constant or quintessence matter

Holger Cleve, Andreas Zeller

A program fails. Under which circumstances does this failure occur? One single algorithm, the delta debugging algorithm, suffices to determine these failure-inducing circumstances. Delta debugging tests a program systematically and automatically to isolate failure-inducing circumstances such as the program input, changes to the program code, or executed stat

F. Bagnoli, F. Cecconi

A synchronization mechanism driven by annealed noise is studied for two replicas of a coupled-map lattice which exhibits stable chaos (SC), i.e. irregular behavior despite a negative Lyapunov spectrum. We show that the observed synchronization transition, on changing the strength of the stochastic coupling between replicas, belongs to the directed percolatio

Michel J. P. Gingras, Byron C. den Hertog

Recent experiments suggest that the Ising pyrochlore magnets ${\rm Ho_{2}Ti_{2}O_{7}}$ and ${\rm Dy_{2}Ti_{2}O_{7}}$ display qualitative properties of the ferromagnetic nearest neighbor spin ice model proposed by Harris {\it et al.}, Phys. Rev. Lett. {\bf 79}, 2554 (1997). The manifestation of spin ice behavior in these systems {\it despite} the energetic co

T. L. Einstein, Howard L. Richards, Saul D. Cohen, O. Pierre-Louis

For more than three decades, measurement of terrace width distributions (TWDs) of vicinal crystal surfaces have been recognized as arguably the best way to determine the dimensionless strength $\tilde{A}$ of the elastic repulsion between steps. For sufficiently strong repulsions, the TWD is expected to be Gaussian, with $\tilde{A}$ varying inversely with the

M. Y. Choi, Sung Wu Rhee, Minchul Lee, J. Choi

We study the quantum phase transition in a chain of superconducting grains, coupled by Josephson junctions, with emphasis on the effects of gate charges induced on the grains. At zero temperature the system is mapped onto a two-dimensional classical Coulomb gas, where the gate charge plays the role of an imaginary electric field. Such a field is found releva

P. Bartlett, S. I. Henderson, S. J. Mitchell

The hydrodynamic forces between Brownian spheres are determined from a measurement of the correlated thermal fluctuations in particle position using a new method, two-particle cross-correlation spectroscopy (TCS). A pair of 1.3 um diameter polymer-coated poly(methyl methacrylate) were held at separations of between 2 um and 20 um using optical traps. The mob

M. Disertori, J. Magnen, V. Rivasseau

In this paper we complete the first step, namely the uniform bound on completely convergent contributions, towards proving that a three dimensional interacting system of Fermions is a Fermi liquid in the sense of Salmhofer. The analysis relies on a direct space decomposition of the propagator, on a bosonic multiscale cluster expansion and on the Hadamard ine

V. N. Dumachev, V. N. Nechaev

In frameworks of the macroscopic dynamic theory of coherent interfaces in crystals the acoustic radiation of coherent boundary at passage along it of localized wave packages is considered. It is shown that the coherent twin boundary of acoustic waves does not radiate.

Vladimir E. Korepin, Itzhak Roditi

We consider the repulsive Hubbard model in one dimension and show the different mechanisms present in the charge and spin separation phenomena for an electron, at half filling and bellow half filling. We also comment recent experimental results.

A. V. Filinov, M. Bonitz, Yu. E. Lozovik

Wigner crystallization of electrons in a 2D quantum dots is reported. It proceeds in two stages: I) via radial ordering of electrons on shells and II) freezing of the inter-shell rotation. The phase boundary of the crystal is computed in the whole temperature--density plane, and the influence of quantum effects and of the particle number is analyzed.

Hendrik Meyer, Florian Mueller-Plathe

The formation of chain-folded structures from the melt is observed in molecular dynamics simulations resembling the lamellae of polymer crystals. Crystallization and subsequent melting temperatures are related linearly to the inverse lamellar thickness. Analysis of the single chain conformations in the crystal shows that most chains reenter the same lamella

Matteo Palassini, A. P. Young

This is a reply to cond-mat/0010033 by Newman and Stein, which is a comment on on our paper Phys. Rev. Lett. 85, 3017 (2000), cond-mat/0002134.

A. Bachtold, M. de Jonge, K. Grove-Rasmussen, P. L. McEuen

We have studied tunneling of electrons into multi-wall carbon nanotubes. Nanotube/electrode interfaces with low transparency as well as nanotube/nanotube junctions created with atomic force microscope manipulation have been used. The tunneling conductance goes to zero as the temperature and bias are reduced, and the functional form is consistent with a power

C. Petrovic, R. Movshovich, M. Jaime, P. G. Pagliuso

CeIrIn5 is a member of a new family of heavy-fermion compounds and has a Sommerfeld specific heat coefficient of 720 mJ/mol-K2. It exhibits a bulk, thermodynamic transition to a superconducting state at Tc=0.40 K, below which the specific heat decreases as T2 to a small residual T-linear value. Surprisingly, the electrical resistivity drops below instrumenta

J. D. Thompson, R. Movshovich, Z. Fisk, F. Bouguet

We report a new family of Ce-based heavy-fermion compounds whose electronic specific heat coefficients range from about 400 to over 700 mJ/mole Ce-K2. Crystal in this family form as CenTmIn3n+2m, where T=Rh or Ir, n=1 or 2, and m=1, with a tetragonal structure that can be viewed as n-layers of CeIn3 units stacked sequentially along the c-axis with intervenin

J. S. Andrade, M. Filoche, B. Sapoval

The concept of an active zone in Laplacian transport is used to obtain an analytical approximation for the reactive effectiveness of a pore with an arbitrary rough geometry. We show that this approximation is in very good agreement with direct numerical simulations performed over a wide range of diffusion-reaction conditions (i.e., with or without screening

R. J. Radwanski, Z. Ropka

We criticize the model proposed by Mila et al. (Phys.Rev.Lett. 85 (2000) 1714) for the description of the V3+ ion in V2O3 by pointing out that it is completely artificial because the condition about the degenerate (doublet) orbital ground state required for the authors' model cannot be realized in the reality. We claim that the V3+ ion should be consider

R. P. Sear, J. A. Cuesta

Ideal bosons and classical ring polymers formed via self-assembly, are known to have the same partition function, and so analogous phase transitions. In ring polymers, the analogue of Bose-Einstein condensation occurs when a ring polymer of macroscopic size appears. We show that a transition of the same general form occurs within a whole class of systems wit

A. R. Lima, T. J. P. Penna, P. M. C. de Oliveira

This is a reply to the comment by M. Kastner and M. Promberger [cond-mat/0011516] on the paper published in J. Stat. Phys. 99, 691 (2000) and also in cond-mat/0002176. We show that all their criticisms do not apply.

Geza Odor

Recently an exact solution has been found (M.Henkel and H.Hinrichsen, cond-mat/0010062) for the 1d coagulation production process: 2A ->A, A0A->3A with equal diffusion and coagulation rates. This model evolves into the inactive phase independently of the production rate with $t^{-1/2}$ density decay law. Here I show that cluster mean-field approximations and

E. Le Goff, L. Barbier, B. Salanon

We introduce a {\it lattice} version of the Calogero Sutherland model adapted to describe $1/d^2$ pairwise interacting steps with discrete positions on a vicinal surface. The configurational free energy is obtained within a transfer matrix method. The full phase diagram for attractive and for repulsive interaction is deduced. For attraction, critical tempera

T. P. Pareek, Patrick Bruno

We report numerical simulation result of a recently proposed \{P. Bruno, Phys. Rev. Lett {\bf 79}, 4593, (1997)\} approach to perform magnetic scanning tunneling microscopy with a two terminal non-magnetic tip. It is based upon the spin asymmetry effect of the tunneling current between a ferromagnetic surface and a two-terminal non-magnetic tip. The spin asy

Cyprien Gay, Elie Raphael

A new method of polymer characterization, based on permeation studies using nanoscale pores, was recently proposed by Brochard and de Gennes. In the present paper, we study how this method, initially developped for star polymers can be extended to comb-like polymers.

J. A. Torres, J. J. Saenz

An easy to implement and powerful method for the solution of 3D scattering problems that can be well described by Helmholtz equation is presented. The matrix algebra used provides excellent stability versus the number of junctions as well as great computational speed. The matrix truncation method yields an easy single-parameter convergence procedure. Subsequ

P. W. Brouwer

Rectification of ac displacement currents generated by periodic variation of two independent gate voltages of a quantum dot can lead to a dc voltage linear in the frequency. The presence of this rectified displacement current could account for the magnetic field symmetry observed in a recent measurement on an adiabatic quantum electron pump by Switkes et al.

D. N. Aristov

We investigate, both analytically and numerically, the behavior of the electron gas on a sphere in the presence of point-like impurities. We find a criterion when the disorder can be regarded as small one and the main effect is the broadening of rotational multiplets. In the latter regime the statistics of one impurity-induced band is studied numerically. Th

Julio F. Navarro

I highlight recent progress in our understanding of the origin of disk galaxy scaling laws in a hierarchically clustering universe. Numerical simulations of galaxy formation in Cold Dark Matter (CDM) dominated universes indicate that the slope and scatter of the I-band Tully-Fisher (TF) relation are well reproduced in this model, although not, as proposed in

Andrew Moore, Andy Connolly, Chris Genovese, Alex Gray

We present here a new algorithm for the fast computation of N-point correlation functions in large astronomical data sets. The algorithm is based on kdtrees which are decorated with cached sufficient statistics thus allowing for orders of magnitude speed-ups over the naive non-tree-based implementation of correlation functions. We further discuss the use of

G. Weidenspointner, M. Varendorff, U. Oberlack, D. Morris

The instrumental line background of the Compton telescope COMPTEL onboard the Compton Gamma-Ray Observatory is due to the activation and/or decay of many isotopes. The major components of this background can be attributed to eight individual isotopes, namely 2D, 22Na, 24Na, 28Al, 40K, 52Mn, 57Ni, and 208Tl. The identification of instrumental lines with speci

B. R. McNamara, M. W. Wise, L. P. David, P. E. J. Nulsen

We discuss new results from the Chandra X-ray Observatory and XMM-Newton on cluster cooling flows, emphasizing early results from our Chandra programs. We find cooling rates reduced by factors of 5-10 compared to those from earlier missions. Nevertheless, substantial amounts of keV gas appear to be cooling and fueling star formation in central dominant clust

H. Baumgardt

We report results of collisional N-body simulations aimed to study the N-dependance of the dynamical evolution of star clusters. Our clusters consist of equal-mass stars and are in virial equilibrium. Clusters moving in external tidal fields and clusters limited by a cut-off radius are simulated. Our main focus is to study the dependence of the lifetimes of

Parviz Ghavamian, John C. Raymond, William P. Blair

We present far ultraviolet spectra of a fast (~ 300 km/s) nonradiative shock in the Cygnus Loop supernova remnant. Our observations were performed with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite, covering the wavelength range 905-1187 Angstroms. The purpose of these observations was to estimate the degree of electron-ion equilibration by (1)

Michael J. Ledlow, Frazer N. Owen, Min S. Yun, John M. Hill

We have identified a large (~200 kpc), powerful double radio source whose host galaxy is clearly a disk and most likely a spiral. This FR I radio galaxy is located very near the center of the RC 0 cluster Abell 428. The existence of such an object violates a fundamental paradigm for radio loud AGN. In paper I, we showed that this object was most likely a spi

Mark J. Devlin

A new generation of sub-orbital platforms will be operational in the next few years. These new telescopes will operate from airborne and balloon-borne platforms where the atmosphere is transparent enough to allow sensitive measurements to be made in the submillimeter bands. The telescopes will take advantage of state-of-the-art instrumentation including larg

Joanne C. Baker, Richard W. Hunstead, Malcolm N. Bremer, Joss Bland-Hawthorn

Using a combination of multicolour broad- and narrow-band imaging techniques and follow-up spectroscopy, we have detected an overdensity of galaxies in the field of quasar MRC B0450-221, whose properties are consistent with a cluster at the quasar redshift z=0.9. An excess of red galaxies (V-I>2.2, I-K'>3.8) is evident within 1' of the quasar, with t

A. I. Silva, S. M. Viegas

We calculate theoretical population ratios of the ground fine-structure levels of some atoms/ions which typically exhibit UV lines in the spectra of QSO absorbers redward the Ly-alpha forest: C0, C+, O0, Si+ and Fe+. The most reliable atomic data available is employed and a variety of excitation mechanisms considered: collisions with several particles in the

Martin E. Sulkanen, Joel N. Bregman

Recently it has been suggested that the hard x-ray power-law tails exhibited in the ASCA spectra of several nearby giant elliptical galaxies are caused by low-radiative efficiency accretion flows (ADAFs) onto a massive black hole in the centers of the galaxies. The estimated fluxes from these central ADAFs as derived from the ASCA x-ray spectral analyses ind

Klaus Strobel, Manfred K. Weigel

The minimum and maximum mass of protoneutron stars and neutron stars are investigated. The hot dense matter is described by relativistic (including hyperons) and non-relativistic equations of state. We show that the minimum mass ($\sim$ 0.88 - 1.28 $M_{\sun}$) of a neutron star is determined by the earliest stage of its evolution and is nearly unaffected by

P. Naselsky, D. Novikov, I. Novikov, J. Silk

We propose a technique for determination of the spectral parameters of the cosmological signal and pixel noise using observational data on CMB polarization without any additional assumptions. We introduce the notion of so called crossing points in the observational maps and derive the theoretical dependence of the total number of crossing points at different

L. Amati, F. Frontera, M. Vietri, J. J. M. in't Zand

We report the discovery of a transient equivalent hydrogen column density with an absorption edge at ~3.8 kiloelectron volts in the spectrum of the prompt x-ray emission of gamma-ray burst (GRB) 990705. This feature can be satisfactorily modeled with a photoelectric absorption by a medium located at a redshift of ~0.86 and with an iron abundance of ~75 times

I. E. Papadakis, W. Brinkmann, H. Negoro, E. Detsis

The Narrow-line Seyfert galaxy Ark 564 was monitored between June 04, 2000 and June 24, 2000 from Skinakas Observatory. The B,V,R and I band light curves show night to night variations of 0.1 mag. Comparison with X-ray data from a simultaneous ASCA observation shows that the X-ray variations are more pronounced than in the optical band. Cross correlation ana

A. Y. Potekhin, G. Chabrier, D. G. Yakovlev

Outer envelopes of neutron stars consist mostly of fully ionized, strongly coupled Coulomb plasmas characterized by typical densities about 10^4-10^{11} g/cc and temperatures about 10^4-10^9 K. Many neutron stars possess magnetic fields about 10^{11}-10^{14} G. Here we briefly review recent theoretical advances which allow one to calculate thermodynamic func

B. Vollmer, W. J. Duschl

We present a first attempt to construct an analytic model for a clumped gas and dust disk and apply it to the Galactic Centre. The clumps are described as isothermal spheres partially ionized by the external UV radiation field. The disk structure formed by the clouds is described as a quasi standard continuous accretion disk using adequately averaged paramet

Kei-ichi Maeda

We propose a new quintessence scenario in the brane cosmology, assuming that a quintessence field $Q$ is confined in our 3-dimensional brane world. With a potential $V(Q)= μ^{α+4} Q^{-α}~(α\geq 2)$, we find that the density parameter of the scalar field decreases as $Ω_Q \sim a^{-4(α-2)/(α+2)}$ in the epoch of quadratic energy density dominance, if $α\leq 6$

Kenji Bekki, Yasuhiro Shioya

By using a new numerical code for deriving the spectral energy distributions of galaxies, we have investigated the time evolution of morphological properties, the star formation rate, and the submillimeter flux at 850 $μ$m in high-redshift ($z$) dusty starburst mergers with mass ratio ($m_{2}$) of two disks ranging from 0.1 (minor merger) to 1.0 (major one).

M. Odenkirchen, E. K. Grebel, C. M. Rockosi, W. Dehnen

We report the discovery of two well-defined tidal tails emerging from the sparse remote globular cluster Palomar 5. These tails stretch out symmetrically to both sides of the cluster in the direction of constant Galactic latitude and subtend an angle of 2.6 degrees on the sky. The tails have been detected in commissioning data of the Sloan Digital Sky Survey

H. Murakami, K. Koyama, M. Tsujimoto, Y. Maeda

We present an ASCA discovery of diffuse hard X-ray emission from the Sgr C complex with its peak in the vicinity of the molecular cloud core. The X-ray spectrum is characterized by a strong 6.4-keV line and large absorption. These properties suggest that Sgr C is a new X-ray reflection nebula which emits fluorescent and scattered X-rays via irradiation from

E. Pointecouteau, M. Giard, F. X. Désert, B. Alain

We present in this letter a high resolution (22'' FWHM) extended map at 2.1mm of the Sunyaev-Zel'dovich effect toward the most luminous X-ray cluster, RXJ1347-1145. These observations have been performed with the DIABOLO photometer working at the focus of the 30m IRAM radiotelescope. We have derived a projected gas mass of $(1.1 \pm 0.1)\times 10

Kenji Bekki

We numerically investigate dynamical evolution of a merger between a central massive black hole (MBH) and a gas clump with the mass of $10^6$ $-$ $10^7$ $M_{\odot}$ in the central tens pc of a galactic bulge. We found that strong tidal gravitational field of the MBH transforms the initial spherical clump into a moderately thick gaseous disk (or torus) around

Paul Harding, Heather L. Morrison, Edward W. Olszewski, John Arabadjis

We have simulated the evolution of tidal debris in the Galactic halo in order to guide our ongoing survey to determine the fraction of halo mass accreted via satellite infall. Contrary to naive expectations that the satellite debris will produce a single narrow velocity peak on a smooth distribution, there are many different signatures of substructure, inclu

Oleg Y. Gnedin, Dmitry G. Yakovlev, Alexander Y. Potekhin

The internal properties of the neutron star crust can be probed by observing the epoch of thermal relaxation. After the supernova explosion, powerful neutrino emission quickly cools the stellar core, while the crust stays hot. The cooling wave then propagates through the crust, due to its finite thermal conductivity. When the cooling wave reaches the surface

J. E. Taylor, Arif Babul

We have developed a simple yet surprisingly accurate analytic scheme for tracking the dynamical evolution of substructure within larger dark halos. The scheme incorporates the effects of dynamical friction, tidal mass loss and tidal heating via physically motivated approximations. Using our scheme, we can predict the orbital evolution and mass-loss history o

K. M. Mertes, Y. Zhong, M. P. Sarachik, Y. Paltiel

We report Hall sensor measurements of the magnetic relaxation of Mn$_{12}$ acetate as a function of magnetic field applied along the easy axis of magnetization. Data taken at a series of closely-spaced temperatures between 0.24 K and 1.4 K provide strong new evidence for an abrupt ``first-order'' transition between thermally-assisted relaxation and m

P. A. Price, F. A. Harrison, T. J. Galama, D. E. Reichart

We present multi-color light-curves of the optical afterglow of GRB 000926. Beginning ~1.5 days after the burst, the light-curves of this GRB steepen measurably. The existence of such achromatic breaks are usually taken to be an important observational signature that the ejecta are not expanding isotropically, but rather have a collimated jet-like geometry.

Sheldon Stone

I discuss some key issues covered at the Conference including physics goals, current results on CKM angles, rare decays, status of $|V_{cb}|$ and $|V_{ub}|$, CKM fits and progress on hardware.

Tarun Kanti Ghosh, G. Baskaran

Composite Fermion approach using extensive and parallalized numerical analysis has recently established a two-roton bound state as the lowest energy long wavelength neutral excitation of FQHE for finite particle (N~30) system. By focussing on the "oriented dipole" character of magneto roton, we model the two roton problem and solve it variationally (

M. J. Bhaseen, J. -S. Caux, I. I. Kogan, A. M. Tsvelik

We compare the critical multipoint correlation functions for two-dimensional (massless) Dirac fermions in the presence of a random su(N) (non-Abelian) gauge potential, obtained by three different methods. We critically reexamine previous results obtained using the replica approach and in the limit of infinite disorder strength and compare them to new results

Y. J. Kim, R. J. Birgeneau, F. C. Chou, R. W. Erwin

We report a neutron scattering study of the long-wavelength dynamic spin correlations in the model two-dimensional $S=1/2$ square lattice Heisenberg antiferromagnets Sr$_2$CuO$_2$Cl$_2$ and Sr$_2$Cu$_3$O$_4$Cl$_2$. The characteristic energy scale, $ω_0 (T/J)$, is determined by measuring the quasielastic peak width in the paramagnetic phase over a wide range

Jiri Vala, Ronnie Kosloff

A coherent mechanism of robust population inversion in atomic and molecular systems by a chirped field is presented. It is demonstrated that a field of sufficiently high chirp rate imposes a certain relative phase between a ground and excited state wavefunction of a two-level system. The value of the relative phase angle is thus restricted to be negative and

Riccardo Argurio, Amit Giveon, Assaf Shomer

We consider string theory on a background of the form AdS_3 x N. Our aim is to give a description of the dual CFT in a general set up. With the requirement that we have N=2 supersymmetry in spacetime, we provide evidence that the dual CFT is in the moduli space of a certain symmetric product M^p/S_p. On the way to show this, we reproduce some recent results

A. Ali, D. London

Present experiments in pursuit of the mass difference in the Bs-Bs(bar) system have put a lower bound on this quantity of $ΔM_s > 14.9 ps^{-1}$ (at 95% C.L.). The same experiments also yield a local minimum in the log-likelihood function around $ΔM_s = 17.7 ps^{-1}$, which is $2.5σ$ away from being zero. Motivated by these observations, we investigate the co

Ludwik Dabrowski, Giovanni Landi, Tetsuya Masuda

We introduce noncommutative algebras $A_q$ of quantum 4-spheres $S^4_q$, with $q\in\IR$, defined via a suspension of the quantum group $SU_q(2)$, and a quantum instanton bundle described by a selfadjoint idempotent $e\in \Mat_4(A_q)$, $e^2=e=e^*$. Contrary to what happens for the classical case or for the noncommutative instanton constructed in Connes-Landi,

Hai-Yang Cheng, Kwei-Chou Yang

We analyze the decay $B\to ϕK$ within the framework of QCD-improved factorization. We found that although the twist-3 kaon distribution amplitude dominates the spectator interactions, it will suppress the decay rates slightly. The weak annihilation diagrams induced by $(S-P)(S+P)$ penguin operators, which are formally power-suppressed by order $(Λ/m_b)^2$, a

John Schliemann, Jürgen König, A. H. MacDonald

We report on Monte Carlo studies of the kinetic exchange model for (III,Mn)V ferromagnetic semiconductors in which S=5/2 local moments, representing Mn^{2+} ions, are exchange coupled to band electrons. We treat the Mn^{2+}$ spin orientations as classical degrees of freedom and use the Hybrid Monte Carlo algorithm to explore thermodynamically important Mn sp

G. Mangano, A. Melchiorri, O. Pisanti

We report the results of a recent likelihood analysis combining the primordial nucleosynthesis and the BOOMERanG and MAXIMA-1 data on cosmic microwave background radiation anisotropies. We discuss the possible implications for relic neutrino background of a high value for the baryonic matter content of the universe, larger than what is expected in a standard

Dirk Helbing

Since the subject of traffic dynamics has captured the interest of physicists, many astonishing effects have been revealed and explained. Some of the questions now understood are the following: Why are vehicles sometimes stopped by so-called ``phantom traffic jams'', although they all like to drive fast? What are the mechanisms behind stop-and-go tra

D. Gorbunov, V. Ilyin, B. Mele

We study top-quark decays in models with light sgoldstinos. The off-diagonal entries in the squark mass matrices can lead to FCNC top two-body decays into sgoldstinos and u(c) quarks. We compute the rates for these decays and discuss the corresponding signatures that could manifest the presence of sgoldstinos in top decays at LHC. We expect that a supersymme

Gui Lu Long, Xiao Shu Liu

A theoretical quantum key distribution scheme using EPR pairs is presented. This scheme is efficient in that it uses all EPR pairs in distributing the key except those chosen for checking eavesdroppers. The high capacity is achieved because each EPR pair carries 2 bits of key code.

Xiaoguang Wang, Anders Sorensen, Klaus Molmer

We present a general technique to implement products of many qubit operators communicating via a joint harmonic oscillator degree of freedom in a quantum computer. By conditional displacements and rotations we can implement Hamiltonians which are trigonometric functions of qubit operators. With such operators we can effectively implement higher order gates s

S. Abel, D. Bailin, S. Khalil, O. Lebedev

We revisit the supersymmetric CP problem and find that it can be naturally resolved if the origin of CP violation is closely related to the origin of flavour structures. In this case, the supersymmetry breaking dynamics do not bring in any new CP-violating phases. This mechanism requires hermitian Yukawa matrices which naturally arise in models with a U(3) f

Hsiang-nan Li

We prove factorization theorem for the processes $πγ^*\toγ$ and $πγ^*\toπ$ to leading twist in the covariant gauge by means of the Ward identity. Soft divergences cancel and collinear divergences are grouped into a pion wave function defined by a nonlocal matrix element. The gauge invariance and universality of the pion wave function are confirmed. The proof

D. K. Park, S. Tamaryan, H. J. W. Müller-Kirsten

A Born--Infeld theory describing a $D2$--brane coupled to a 3--form RR potential is reconsidered and a new type of static solution is obtained which is even stable.

Martin J. Savage

Parity violation in low-energy nuclear observables is included in the pionless effective field theory. The model-independent relation between the parity-violating asymmetry in polarized np -> d gamma and the non-nucleon part of the deuteron anapole moment is discussed. The asymmetry in np -> d gamma computed with KSW power-counting, and recently criticized b

C. H. Chung, J. B. Marston, Ross H. McKenzie

We solve the Sp(N) Heisenberg and SU(N) Hubbard-Heisenberg models on the anisotropic triangular lattice in the large-N limit. These two models may describe respectively the magnetic and electronic properties of the family of layered organic materials $κ$-(BEDT-TTF)$_2$X. The Heisenberg model is also relevant to the frustrated antiferromagnet, Cs$_2$CuCl$_4$.

Ulvi Yurtsever

A long sequence of tosses of a classical coin produces an apparently random bit string, but classical randomness is an illusion: the algorithmic information content of a classically-generated bit string lies almost entirely in the description of initial conditions. This letter presents a simple argument that, by contrast, a sequence of bits produced by tossi

P. van Loock, Samuel L. Braunstein

We propose entangled (M+1)-mode quantum states as a multiuser quantum channel for continuous-variable communication. Arbitrary quantum states can be sent via this channel simultaneously to M remote and separated locations with equal minimum excess noise in each output mode. For a set of coherent-state inputs, the channel realizes optimum symmetric 1-to-M clo

R. Folman, J. Schmiedmayer, H. Ritsch, D. Vitali

Recently it has been proposed to use parity as a measure of the mechanism behind decoherence or the transformation from quantum to classical. Here, we show that the proposed experiment is more feasible than previously thought, as even an initial thermal state would exhibit the hypothesized symmetry breaking.

A. F. R. de Toledo Piza, M. C. Nemes

We analyse a class of quantum dynamical processes which may lead to the hindering of the decay of a non-stationary state through appropriate entanglement with an additional two-level system. In this case the process can be considered as a module whose iteration is related to dynamical implementations of the so called quantum Zeno effect.