849 research outputs found
Probing the spin-parity of the Higgs boson via jet kinematics in vector boson fusion
Determining the spin and the parity quantum numbers of the recently
discovered Higgs-like boson at the LHC is a matter of great importance. In this
paper, we consider the possibility of using the kinematics of the tagging jets
in Higgs production via the vector boson fusion (VBF) process to test the
tensor structure of the Higgs-vector boson () interaction and to determine
the spin and CP properties of the observed resonance. We show that an anomalous
vertex, in particular its explicit momentum dependence, drastically
affects the rapidity between the two scattered quarks and their transverse
momenta and, hence, the acceptance of the kinematical cuts that allow to select
the VBF topology. The sensitivity of these observables to different spin-parity
assignments, including the dependence on the LHC center of mass energy, are
evaluated. In addition, we show that in associated Higgs production with a
vector boson some kinematical variables, such as the invariant mass of the
system and the transverse momenta of the two bosons and their separation in
rapidity, are also sensitive to the spin--parity assignments of the Higgs--like
boson.Comment: 15 pages, 5 figure
Signatures of anomalous VVH interactions at a linear collider
We examine, in a model independent way, the sensitivity of a Linear Collider
to the couplings of a light Higgs boson to gauge bosons. Including the
possibility of CP violation, we construct several observables that probe the
different anomalous couplings possible. For an intermediate mass Higgs, a
collider operating at a center of mass energy of 500 GeV and with an integrated
luminosity of 500 fb is shown to be able to constrain the vertex
at the few per cent level, and with even higher sensitivity in certain
directions. However, the lack of sufficient number of observables as well as
contamination from the vertex limits the precision with which the
coupling can be measured.Comment: Typeset in RevTeX4, 16 pages, 12 figures; V2: minor changes in title
and Sec. II and III; V3: version appeared in PRD with minor correctio
Probing CP-violating Higgs contributions in gamma-gamma -> f anti-f through fermion polarization
We discuss the use of fermion polarization for studying neutral Higgs bosons
at a photon collider. To this aim we construct polarization asymmetries which
can isolate the contribution of a Higgs boson in , , from that of the QED continuum. This can help in getting
information on the coupling in case is a CP
eigenstate. We also construct CP-violating asymmetries which can probe CP
mixing in case has indeterminate CP. Furthermore, we take the MSSM with
CP violation as an example to demonstrate the potential of these asymmetries in
a numerical analysis. We find that these asymmetries are sensitive to the
presence of a Higgs boson as well as its CP properties over a wide range of
MSSM parameters. In particular, the method suggested can cover the region where
a light Higgs boson may have been missed by LEP due to CP violation in the
Higgs sector, and may be missed as well at the LHC.Comment: 14 pages, 14 figures, typeset in revtex4. Version which has appeared
in Physical Review D; typos in two references correcte
Why the angular distribution of the top decay lepton is unchanged by anomalous coupling
We give a simple physical argument to understand the observation that the
angular distribution of the top decay lepton depends only on the polarisation
of the top and is independent of any anomalous coupling to linear order.Comment: 4 pages, 2 figures. Added a footnote and consequently a few
reference
Bounds on R-parity violating SUSY Yukawa couplings from semileptonic decays of baryons
We consider tree-level corrections to hypercharge changing semileptonic
decays of certain baryons induced by a minimal supersymmetric standard model
with explicitly broken R-parity via -violation. This study leads to a new
set of constraints on the products of couplings arising from the LQd
operator of the superpotential.Comment: Latex (8 pages), no figur
Looking for the gluonic EMC effect in associated + production
We study the associated production of in fixed-target
experiments with nuclear targets as well as at the relativistic heavy-ion
collider (RHIC). We find that this process affords a very clean probe of
, the ratio of gluon density in a heavy nucleus to that of a proton.
The combined range thus available can be used to discriminate between the
predictions of different models of the EMC effect for .Comment: 10 pages, 4 Figures (not included, available only by p-mail), LaTeX,
CERN-TH.6679/92, TIFR/TH/92-59, BU-TH-92/3, Minor revision. Replaced version
has the style file equation.sty appended for easy processing, which is the
only chang
J/ψ production via fragmentation at HERA
We compute the contributions to large-pTJ/ψ production at DHEA coming from fragmentation of gluons and charm quarks. We find that the charm quark fragmentation contribution dominates over the direct production of J/ψ via photongluon fusion at large-pT, while the gluon fragmentation is negligibly small over the whole range of pT. An experimental study of pT distributions of J/ψ at HERA will providea direct probe of the charm quark fragmentation functions
VDAC PROPERTIES ARE INFLUENCED BY THE SOURCE OF ITS PURIFICATION
Objectives: The Voltage Dependent Anion-Selective Channel (VDAC), the most abundant protein of the outer mitochondrial membrane (OMM), forms the major conduit for metabolite transport across this membrane. It has also been shown to be involved in cell death signalling through interaction with other proteins like Hexokinase and by mediating release of apoptogenic proteins like cyt c from mitochondria. As in case of other channel proteins, functional characterization of purified reconstituted protein by using electrophysiological techniques can be used in development of VDAC targeted drugs. Here we report electrophysiological properties of VDACs (one of the target for cancerous cells) purified from different sources.
Methods: Human VDAC1 and rice VDAC4 were heterologously expressed and purified from E. coli BL21 (DE3)-pLysS, while rat and yeast VDACs were purified from mitochondria. Electrophysiological studies of all VDACs were done by using BLM and the data was analysed by using pCLAMP 10 (Axon Instruments).
Results: VDACs purified from both the sources showed conserved voltage dependence and channel conductance, however they showed significant difference in dynamics. VDAC purified from mitochondria had relatively short occupancy of each electrophysiological state compared to protein purified from inclusion bodies.
Conclusion: Our results suggest that the source of purified protein could be critical for some aspects of channel function
Probing the CP nature of the Higgs bosons by top-pair production at photon linear colliders
We study effects of heavy Higgs bosons on the top-pair production process at
photon linear colliders. The interference patterns between the resonant
Higgs-production amplitudes and the continuum QED amplitudes are examined. The
patterns tell us not only the CP nature of the Higgs bosons but also the phase
of the --Higgs vertex which gives new information about the Higgs
couplings to new charged particles. We point out that it is necessary to use
circularly polarized photon beams to produce efficiently heavy Higgs bosons
whose masses exceed the electron beam energy, and show that the above
interference patterns of the production amplitudes can be studied by observing
top decay angular distributions. Analytic expressions for the helicity
amplitudes for the sequential process are presented in
terms of the generic production amplitudes.Comment: 34 pages, LATEX file with 6 PS figures, comments adde
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