94,130 research outputs found
Higgs Boson And Scattering At Colliders
We discuss the Standard-Model Higgs boson production in the channels
, , and W^-W^-H^{--}e^-e^-$ Workshop, Santa Cruz, CA,
Sept. 4--5, 1995. 13 pages, 5 figs, LaTeX; postscript file available via
anonymous ftp at ftp://ucdhep.ucdavis.edu/han/sews/emem_sc.p
Measuring CP Violating Phases at a Future Linear Collider
At a future Linear Collider one will be able to determine the masses of
charginos and neutralinos and their pair production cross sections to high
accuracies. We show how systematically including the cross sections into the
analysis improves the measurement of the underlying mass parameters, including
potential CP violating phases. In addition, we investigate how experimental
errors will affect the determination of these parameters. We present a first
estimate on the lower limit of observable small phases and on the accuracy in
determining large phases.Comment: 10 pages, 6 figures, RevTeX3.1, Version to be published in Physics
Letters B, physics setup improved, figures added, conclusions unchange
On the complexity of computing maximum entropy for Markovian models
We investigate the complexity of computing entropy of various Markovian models including Markov Chains (MCs), Interval Markov Chains (IMCs) and Markov Decision Processes (MDPs). We consider both entropy and entropy rate for general MCs, and study two algorithmic questions, i.e., entropy approximation problem and entropy threshold problem. The former asks for an approximation of the entropy/entropy rate within a given precision, whereas the latter aims to decide whether they exceed a given threshold. We give polynomial-time algorithms for the approximation problem, and show the threshold problem is in P CH3 (hence in PSPACE) and in P assuming some number-theoretic conjectures. Furthermore, we study both questions for IMCs and MDPs where we aim to maximise the entropy/entropy rate among an infinite family of MCs associated with the given model. We give various conditional decidability results for the threshold problem, and show the approximation problem is solvable in polynomial-time via convex programmin
Local Spin Susceptibility of the S=1/2 Kagome Lattice in ZnCu3(OD)6Cl2
We report single-crystal 2-D NMR investigation of the nearly ideal spin S=1/2
kagome lattice ZnCu3(OD)6Cl2. We successfully identify 2-D NMR signals
originating from the nearest-neighbors of Cu2+ defects occupying Zn sites. From
the 2-D Knight shift measurements, we demonstrate that weakly interacting Cu2+
spins at these defects cause the large Curie-Weiss enhancement toward T=0
commonly observed in the bulk susceptibility data. We estimate the intrinsic
spin susceptibility of the kagome planes by subtracting defect contributions,
and explore several scenarios.Comment: 4 figures; published in PR-B Rapid Communication
Dynamics of Scalar Field in Polymer-like Representation
In recent twenty years, loop quantum gravity, a background independent
approach to unify general relativity and quantum mechanics, has been widely
investigated. We consider the quantum dynamics of a real massless scalar field
coupled to gravity in this framework. A Hamiltonian operator for the scalar
field can be well defined in the coupled diffeomorphism invariant Hilbert
space, which is both self-adjoint and positive. On the other hand, the
Hamiltonian constraint operator for the scalar field coupled to gravity can be
well defined in the coupled kinematical Hilbert space. There are 1-parameter
ambiguities due to scalar field in the construction of both operators. The
results heighten our confidence that there is no divergence within this
background independent and diffeomorphism invariant quantization approach of
matter coupled to gravity. Moreover, to avoid possible quantum anomaly, the
master constraint programme can be carried out in this coupled system by
employing a self-adjoint master constraint operator on the diffeomorphism
invariant Hilbert space.Comment: 24 pages, accepted for pubilcation in Class. Quant. Gra
A variational approach for continuous supply chain networks
We consider a continuous supply chain network consisting of buffering queues and processors first proposed by [D. Armbruster, P. Degond, and C. Ringhofer, SIAM J. Appl. Math., 66 (2006), pp. 896–920] and subsequently analyzed by [D. Armbruster, P. Degond, and C. Ringhofer, Bull. Inst. Math. Acad. Sin. (N.S.), 2 (2007), pp. 433–460] and [D. Armbruster, C. De Beer, M. Fre- itag, T. Jagalski, and C. Ringhofer, Phys. A, 363 (2006), pp. 104–114]. A model was proposed for such a network by [S. G ̈ottlich, M. Herty, and A. Klar, Commun. Math. Sci., 3 (2005), pp. 545–559] using a system of coupling ordinary differential equations and partial differential equations. In this article, we propose an alternative approach based on a variational method to formulate the network dynamics. We also derive, based on the variational method, a computational algorithm that guarantees numerical stability, allows for rigorous error estimates, and facilitates efficient computations. A class of network flow optimization problems are formulated as mixed integer programs (MIPs). The proposed numerical algorithm and the corresponding MIP are compared theoretically and numerically with existing ones [A. Fu ̈genschuh, S. Go ̈ttlich, M. Herty, A. Klar, and A. Martin, SIAM J. Sci. Comput., 30 (2008), pp. 1490–1507; S. Go ̈ttlich, M. Herty, and A. Klar, Commun. Math. Sci., 3 (2005), pp. 545–559], which demonstrates the modeling and computational advantages of the variational approach
TeV resonances in top physics at the LHC
We consider the possibility of studying novel particles at the TeV scale with
enhanced couplings to the top quark via top quark pair production at the LHC
and VLHC. In particular we discuss the case of neutral scalar and vector
resonances associated with a strongly interacting electroweak symmetry breaking
sector. We constrain the couplings of these resonances by imposing appropriate
partial wave unitarity conditions and known low energy constraints. We evaluate
the new physics signals via WW -> tt~ for various models without making
approximation for the initial state W bosons, and optimize the acceptance cuts
for the signal observation. We conclude that QCD backgrounds overwhelm the
signals in both the LHC and a 200 TeV VLHC, making it impossible to study this
type of physics in the tt~ channel at those machines.Comment: 15p, add. comments to clarify model, +2 ref., version to appear PR
Drell-Yan plus missing energy as a signal for extra dimensions
We explore the search sensitivity for signals of large extra dimensions at
hadron colliders via the Drell-Yan process pp -> l+ l- + E_T(miss) X (l = e,mu)
where the missing transverse energy is the result of escaping Kaluza-Klein
gravitons. We find that one is able to place exclusion limits on the gravity
scale up to 560 GeV at the Fermilab Tevatron, and to 4.0 (3.3) TeV at the CERN
LHC, for n = 3 (4) extra dimensions.Comment: 5 pages, 2 PS figs, revised verseion to be published in Physics
Letters
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