114,277 research outputs found
Completing NLO QCD Corrections for Tree Level Non-Leptonic Delta F = 1 Decays Beyond the Standard Model
In various extensions of the Standard Model (SM) tree level non-leptonic
decays of hadrons receive contributions from new heavy gauge bosons and
scalars. Prominent examples are the right-handed W' bosons in left-right
symmetric models and charged Higgs (H^\pm) particles in models with extended
scalar sector like two Higgs doublet models and supersymmetric models. Even in
the case of decays with four different quark flavours involved, to which
penguin operators cannot contribute, twenty linearly independent operators,
instead of two in the SM, have to be considered. Anticipating the important
role of such decays at the LHCb, KEKB and Super-B in Rome and having in mind
future improved lattice computations, we complete the existing NLO QCD formulae
for these processes by calculating O(alpha_s) corrections to matching
conditions for the Wilson coefficients of all contributing operators in the
NDR-\bar{MS} scheme. This allows to reduce certain unphysical scale and
renormalization scheme dependences in the existing NLO calculations. Our
results can also be applied to models with tree-level heavy neutral gauge boson
and scalar exchanges in Delta F = 1 transitions and constitute an important
part of NLO analyses of those non-leptonic decays to which also penguin
operators contribute.Comment: 24 pages, 6 figure
Rise of human intelligence: Comments on Howard (1999)
Based upon the evidence that the best chessplayers in the world are becoming increasingly represented by relatively young individuals, Howard (1999) claimed that human intelligence is rising over generations. We suggest that this explanation has several difficulties, and show that alternative explanations relating to changes in the chess environment, including increased access to chess knowledge, offer better explanations for the increased presence of young players at top-level chess
Systems thinking research - principles and methodologies to grapple with complex real world problems
Transverse mass and invariant mass observables for measuring the mass of a semi-invisibly decaying heavy particle
Formulae are derived for the positions of end-points in the invariant mass
and transverse mass distributions obtained from the products of heavy states
decaying to pairs of semi-invisibly decaying lighter states. Formulae are
derived both for the special case where the two decay chains are identical and
the more general case where they are different. The formulae are tested with a
simple case study of heavy SUSY higgs particles decaying to gauginos at the
LHC.Comment: 13 pages, 8 eps figure
The stransverse mass, MT2, in special cases
This document describes some special cases in which the stransverse mass,
MT2, may be calculated by non-iterative algorithms. The most notable special
case is that in which the visible particles and the hypothesised invisible
particles are massless -- a situation relevant to its current usage in the
Large Hadron Collider as a discovery variable, and a situation for which no
analytic answer was previously known. We also derive an expression for MT2 in
another set of new (though arguably less interesting) special cases in which
the missing transverse momentum must point parallel or anti parallel to the
visible momentum sum. In addition, we find new derivations for already known
MT2 solutions in a manner that maintains manifest contralinear boost invariance
throughout, providing new insights into old results. Along the way, we stumble
across some unexpected results and make conjectures relating to geometric forms
of M_eff and H_T and their relationship to MT2.Comment: 11 pages, no figures. v2 corrects minor typos. v3 corrects an
incorrect statement in footnote 8 and inserts a missing term in eq (3.9). v4
and v5 correct minor typos spotted by reader
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The polymeric conformational effect on capacitive deionization performance of graphene oxide/polypyrrole composite electrode
Exploitation of novel faradic materials is an alternative implementation for solving the problem of poor specific electrosorption capacity that conventional carbon materials are encountered in capacitive deionization. Particularly, composite electrode is just a suitable choice because of its potentially high ion-storage ability. Herein, a cyclic voltammetric treatment method with different low limit of potential window was used to manipulate the polymeric conformation and doping level of graphene oxide/polypyrrole (GO/PPy) composite electrode. Based on it, the effect of polymeric structure on the electrosorption performance was systematically studied. When the low limit of potential window is shifted negatively enough, the irreversible polymeric conformational shrinks of GO/PPy are promoted, which not only hinders the insertion process of ions, but also decreases the doping level of polymer due to the intensive interchain-action produced by more entangled polymeric chain. Thus, the number of intercalated ions should decrease, which is expressed by electrochemical impedance spectroscopy (EIS) results and is proportional to the electrosorption capacity of GO/PPy composite electrode in membrane capacitive deionization (MCDI) process. Our work suggests that the less packing density, higher doping level and more charge delocalization on PPy backbone in electrode are beneficial to enhance its capacitive deionization performance
The s ---> d gamma decay in and beyond the Standard Model
The New Physics sensitivity of the s ---> d gamma transition and its
accessibility through hadronic processes are thoroughly investigated. Firstly,
the Standard Model predictions for the direct CP-violating observables in
radiative K decays are systematically improved. Besides, the magnetic
contribution to epsilon prime is estimated and found subleading, even in the
presence of New Physics, and a new strategy to resolve its electroweak versus
QCD penguin fraction is identified. Secondly, the signatures of a series of New
Physics scenarios, characterized as model-independently as possible in terms of
their underlying dynamics, are investigated by combining the information from
all the FCNC transitions in the s ---> d sector.Comment: 54 pages, 14 eps figure
Periodic homogenization of a pseudo-parabolic equation via a spatial-temporal decomposition
Pseudo-parabolic equations have been used to model unsaturated fluid flow in
porous media. In this paper it is shown how a pseudo-parabolic equation can be
upscaled when using a spatio-temporal decomposition employed in the
Peszyn'ska-Showalter-Yi paper [8]. The spatial-temporal decomposition
transforms the pseudo-parabolic equation into a system containing an elliptic
partial differential equation and a temporal ordinary differential equation. To
strengthen our argument, the pseudo-parabolic equation has been given
advection/convection/drift terms. The upscaling is done with the technique of
periodic homogenization via two-scale convergence. The well-posedness of the
extended pseudo-parabolic equation is shown as well. Moreover, we argue that
under certain conditions, a non-local-in-time term arises from the elimination
of an unknown.Comment: 6 pages, 0 figure
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