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We consider the problem of distributed scheduling in wireless networks. We present two different algorithms whose performance is arbitrarily close to that of maximal schedules, but which require low complexity due to the fact that they do not necessarily attempt to find maximal schedules. The first algorithm requires each link to collect local queue-length information in its neighborhood, and its complexity is independent of the size and topology of the network. The second algorithm is presented for the node-exclusive interference model, does not require nodes to collect queue-length information even in their local neighborhoods, and its complexity depends only on the maximum node degree in the network.

Rare B decays provide an opportunity to probe for new physics beyond the standard model. The effective Hamiltonian for the decay b→sl ϩ l Ϫ predicts the characteristic polarization for the final state lepton. Lepton polarization has, in addition to a longitudinal component P L , two orthogonal components P T and P N lying in and perpendicular to the decay plane. In this article we perform a study of the -polarization asymmetry in the case of SUSY models with large tan ␤ in the inclusive decay B→X s ϩ Ϫ . ͓S0556-2821͑99͒06221-9͔ PACS number͑s͒: 12.60. Jv, 13.25.Hw Recent progress in experiment and theory has made flavor changing neutral current ͑FCNC͒ B decays a stringent test of the standard model ͑SM͒ and a powerful probe of physics beyond the standard model. The first observations ͓1͔ of the inclusive and exclusive radiative decays B→X s ␥ and B →K*␥ have placed the study of rare B decays on a new footing. The observation of b→s␥ by CLEO puts very strong constraints on various new physics beyond the standard model. In the case of B→X s ␥ CLEO Observations give very strong constraints on the charged Higgs boson mass in the two Higgs doublet model. But in minimal supersymmetric standard model ͑MSSM͒ these constraints becomes a bit relaxed because of various cancellations between different superparticle contributions. It is therefore important to study the sensitivity of other FCNC processes to SUSY.Recently the inclusive decay of B→X s l ϩ l Ϫ ͓2,3͔ received considerable attention as a testing ground of SM and new physics. The experimental situations of these decays is very promising with e ϩ e Ϫ and hadronic colliders closing on the observation of exclusive models with lϭ and e final states, respectively. In this decay we can observe various kinematical distributions associated with a final state lepton pair such as lepton pair invariant mass spectrum, lepton pair forward backward asymmetry, etc. Recently another observable, polarization asymmetry, for the B→X s ϩ Ϫ mode has also been proposed by Hewett ͓4͔ which can again be used for more strict checking of effective Hamiltonian governing the decay. In another work ͓5͔ attention has been drawn to the fact that apart from longitudinal polarization of lepton there can be two other orthogonal components of polarizations which are proportional to m l /m b and hence are important for . These components of polarizations, namely, the component in the decay plane ( P T , transverse polarization͒ and the component normal to decay plane ( P N , normal polarization͒. 1 In this paper we will try to examine the sensitivity of these observables with respect to new physics, i.e., MSSM.Among models for physics beyond standard model supersymmetry ͑SUSY͒ is considered to be the most promising candidate. The minimal extension of the standard model ͑MSSM͒ involves chiral superfields Q, U c , D c , L, E c , H 1 , and H 2 which transforms under SU(3) c ϫSU(2) L ϫU(1) Y as Qϵ͑3,2,1/2͒,

We study the electromagnetic fields of an arbitrarily moving charged particle and the radiation reaction on the charged particle using a novel approach. We first show that the fields of an arbitrarily moving charged particle in an inertial frame can be related in a simple manner to the fields of a uniformly accelerated charged particle in its rest frame. Since the latter field is static and easily obtainable, it is possible to derive the fields of an arbitrarily moving charged particle by a coordinate transformation. More importantly, this formalism allows us to calculate the self-force on a charged particle in a remarkably simple manner. We show that the original expression for this force, obtained by Dirac, can be rederived with much less computation and in an intuitively simple manner using our formalism. PACS number(s):The field of a charged particle at rest in an inertial frame is a static Coulomb field which falls as (1/r 2 ) in the standard spherical coordinate system. The field of a charge, moving with uniform velocity, can be obtained by Lorentz transforming the Coulomb field; this field also falls as inverse square of the distance. The situation changes dramatically for a charged particle which is moving with non zero acceleration. The field now has a piece which falls only as (1/r), usually called the radiation field. For a field which decreases as (1/r), the energy flux varies as (1/r 2 ) implying that the same amount of energy flows through spheres of different radii at sufficiently large distances from the charge. Because of this reason, the radiation fields acquire a life of their own and the entire phenomena of electromagnetic radiation hinges on this feature. Due to the continuous transfer of energy from the charged particle to large distances, there will be a damping force acting on the charged particle which is usually called the radiation reaction force. The derivation of radiation reaction force is conceptually and operationally quite complicated and the expression -obtained originally by Dirac (see [4])-has no simple intuitive description.We analyse these issues from a novel point of view in this paper which throws light on the conceptual and mathematical issues involved in this problem. The analysis is motivated by the following issue: Maxwell's equations are not only Lorentz invariant but can also be written in a generally covariant manner. Given a charged particle moving in some arbitrary trajectory, it is always possible to construct a proper coordinate system for such a charged particle. In such a coordinate system, the charge will be at rest for all times but the background metric will be non Minkowskian and -in general -time dependent. The Maxwell's equations in this coordinate system will correspond to that of a stationary charge located in a non trivial (and in general time dependent) metric. The solution to Maxwell's equation in this frame receives time dependent contributions not because of the motion of charged particles but because of the non trivial nature of the background me...

If neutrinos are to be identified with the primary source of ultrahigh energy cosmic rays ͑UHECR͒, their interaction on relic neutrinos is of great importance in understanding their long intergalactic journey. In theories with large compact dimensions, the exchange of a tower of massive spin-2 gravitons ͑Kaluza-Klein excitations͒ gives an extra contribution to → f f and ␥␥ processes along with the opening of a new channel for the neutrinos to annihilate with the relic cosmic neutrino background →G kk to produce bulk gravitons in the extra dimensions. This will affect their attenuation. We compute the contribution of these Kaluza-Klein excitations to the above processes and find that for parameters of the theory constrained by supernova cooling, the contribution does indeed become the dominant contribution above ͱsӍ300 GeV.

This Letter describes a measurement of the muon cross section originating from b-quark decay in the forward rapidity range 2.4<| y(&mgr;)|<3.2 in p&pmacr; collisions at sqrt[s] = 1.8 TeV. The data used in this analysis were collected by the D0 experiment at the Fermilab Tevatron. We find that next-to-leading-order QCD calculations underestimate b-quark production by a factor of 4 in the forward rapidity region.

Temperature‐accelerated sliced sampling (TASS) is an enhanced sampling method for achieving accelerated and controlled exploration of high‐dimensional free energy landscapes in molecular dynamics simulations. With the aid of umbrella bias potentials, the TASS method realizes a controlled exploration and divide‐and‐conquer strategy for computing high‐dimensional free energy surfaces. In TASS, diffusion of the system in the collective variable (CV) space is enhanced with the help of metadynamics bias and elevated‐temperature of the auxiliary degrees of freedom (DOF) that are coupled to the CVs. Usually, a low‐dimensional metadynamics bias is applied in TASS. In order to further improve the performance of TASS, we propose here to use a highdimensional metadynamics bias, in the same form as in a parallel bias metadynamics scheme. Here, a modified reweighting scheme, in combination with artificial neural network is used for computing unbiased probability distribution of CVs and projections of high‐dimensional free energy surfaces. We first validate the accuracy and efficiency of our method in computing the four‐dimensional free energy landscape for alanine tripeptide in vacuo. Subsequently, we employ the approach to calculate the eight‐dimensional free energy landscape of alanine pentapeptide in vacuo. Finally, the method is applied to a more realistic problem wherein we compute the broad four‐dimensional free energy surface corresponding to the deacylation of a drug molecule which is covalently complexed with a β‐lactamase enzyme. We demonstrate that using parallel bias in TASS improves the efficiency of exploration of high‐dimensional free energy landscapes.

Recently proposed stabilization mechanism of the Randall-Sundrum metric gives rise to a scalar radion, which couples universally to matter with a weak interaction ( ≃ 1 TeV) scale. Demanding that gauge boson scattering as described by the effective low enerrgy theory be unitary upto a given scale leads to significant constraints on the mass of such a radion.