7,073 research outputs found
Pair Production of Doubly-Charged Scalars: Neutrino Mass Constraints and Signals at the LHC
We study the pair production of doubly charged Higgs bosons at the Large
Hadron Collider (LHC), assuming the doubly charged Higgs to be part of an
SU(2)_L triplet which generates Majorana masses for left-handed neutrinos. Such
pair-production has the advantage that it is not constrained by the triplet
vacuum expectation value, which tends to make the single production rate rather
small. We point out that, in addition to the Drell-Yan (DY) production
mechanism, two-photon processes also contribute to H++H++ production at a level
comparable to the QCD corrections to the DY channel. Decays of the doubly
charged Higgs into both the l+l+ and W+W+ modes are studied in detail to
optimize the signal observation over the backgrounds. Doubly charged scalars
should be observable at the LHC with 300 fb^-1 integrated luminosity in the ll
channel upto the mass range of 1 TeV even with a branching fraction of about 60
%, and in the WW channel upto a mass of 700 GeV. Such a doubly charged Higgs,
if it is a member of a triplet generating neutrino masses,cannot be long-lived
on the scale of collider detectors although it might lead to a displaced
secondary vertex during its decay if it is lighter than about 250 GeV.Comment: revtex4, 23 pages, 14 figures, version published in Physical Review
Lepton Number Violation and W' Chiral Couplings at the LHC
We study the observability for a heavy Majorana neutrino N along with a new
charged gauge boson W' at the LHC. We emphasize the complementarity of these
two particles in their production and decay to unambiguously determine their
properties. We show that the Majorana nature of N can be verified by the
lepton-number violating like-sign dilepton process, and by polar and azimuthal
angular distributions. The chirality of the W' coupling to leptons and to
quarks can be determined by a polar angle distribution in the reconstructed
frame and an azimuthal angle distribution.Comment: 44 pages, 17 Figures; v2 journal versio
QCD corrections to single slepton production at hadron colliders
We evaluate the cross section for single slepton production at hadron
colliders in supersymmetric theories with R-parity violating interactions to
the next-to-leading order in QCD. We obtain fully differential cross section by
using the phase space slicing method. We also perform soft-gluon resummation to
all order in of leading logarithm to obtain a complete transverse
momentum spectrum of the slepton. We find that the full transverse momentum
spectrum is peaked at a few GeV, consistent with the early results for
Drell-Yan production of lepton pairs. We also consider the contribution from
gluon fusion via quark-triangle loop diagrams dominated by the -quark loop.
The cross section of this process is significantly smaller than that of the
tree-level process induced by the initial annihilation.Comment: one new reference is adde
Discriminative Hessian Eigenmaps for face recognition
Dimension reduction algorithms have attracted a lot of attentions in face recognition because they can select a subset of effective and efficient discriminative features in the face images. Most of dimension reduction algorithms can not well model both the intra-class geometry and interclass discrimination simultaneously. In this paper, we introduce the Discriminative Hessian Eigenmaps (DHE), a novel dimension reduction algorithm to address this problem. DHE will consider encoding the geometric and discriminative information in a local patch by improved Hessian Eigenmaps and margin maximization respectively. Empirical studies on public face database thoroughly demonstrate that DHE is superior to popular algorithms for dimension reduction, e.g., FLDA, LPP, MFA and DLA. ©2010 IEEE.published_or_final_versionThe 2010 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), Dallas, TX., 14-19 March 2010. In IEEE International Conference on Acoustics, Speech and Signal Processing Proceedings, 2010, p. 5586-558
Cross-domain web image annotation
In recent years, cross-domain learning algorithms have attracted much attention to solve labeled data insufficient problem. However, these cross-domain learning algorithms cannot be applied for subspace learning, which plays a key role in multimedia, e.g., web image annotation. This paper envisions the cross-domain discriminative subspace learning and provides an effective solution to cross-domain subspace learning. In particular, we propose the cross-domain discriminative Hessian Eigenmaps or CDHE for short. CDHE connects the training and the testing samples by minimizing the quadratic distance between the distribution of the training samples and that of the testing samples. Therefore, a common subspace for data representation can be preserved. We basically expect the discriminative information to separate the concepts in the training set can be shared to separate the concepts in the testing set as well and thus we have a chance to address above cross-domain problem duly. The margin maximization is duly adopted in CDHE so the discriminative information for separating different classes can be well preserved. Finally, CDHE encodes the local geometry of each training class in the local tangent space which is locally isometric to the data manifold and thus can locally preserve the intra-class local geometry. Experimental evidence on real world image datasets demonstrates the effectiveness of CDHE for cross-domain web image annotation. © 2009 IEEE.published_or_final_versionThe IEEE International Conference on Data Mining Workshops (ICDMW) 2009, Miami, FL., 6 December 2009. In Proceedings of the IEEE International Conference on Data Mining, 2009, p. 184-18
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