859 research outputs found
Use of transverse beam polarization to probe anomalous VVH interactions at a Linear Collider
We investigate use of transverse beam polarization in probing anomalous
coupling of a Higgs boson to a pair of vector bosons, at the International
Linear Collider (ILC). We consider the most general form of VVH (V = W/Z)
vertex consistent with Lorentz invariance and investigate its effects on the
process e+ e- --> f bar{f} H, f being a light fermion. Constructing observables
with definite CP and naive time reversal (tilde T) transformation properties,
we find that transverse beam polarization helps us to improve on the
sensitivity of one part of the anomalous ZZH coupling that is odd under CP.
Even more importantly it provides the possibility of discriminating from each
other, two terms in the general ZZH vertex, both of which are even under CP and
tilde T. Use of transverse beam polarization when combined with information
from unpolarized and linearly polarized beams therefore, allows one to have
completely independent probes of all the different parts of a general ZZH
vertex.Comment: 15 pages, 3 figures, published versio
Strange freezeout
We argue that known systematics of hadron cross sections may cause different
particles to freeze out of the fireball produced in heavy-ion collisions at
different times. We find that a simple model with two freezeout points is a
better description of data than that with a single freezeout, while still
remaining predictive. The resulting fits seem to present constraints on the
late stage evolution of the fireball, including the tantalizing possibility
that the QCD chiral transition influences the yields at sqrt(S)=2700 GeV and
the QCD critical point those at sqrt(S)=17.3 GeV
Processes at High Energy pp Colliders
In this note we investigate the production of charged heavy particles via
\gaga\ fusion at high energy pp colliders. We revise previous claims that the
\gaga\ cross section is comparable to or larger than that for the corresponding
Drell-Yan process at high energies. Indeed we find that the \gaga\ contribution
to the total production cross section at pp is far below the Drell-Yan cross
section. As far as the individual elastic, semi-elastic and inelastic
contributions to the \gaga\ process are concerned we find that they are all of
the same order of magnitude.Comment: REVTEX, 12 pages, two uuencoded figures appended at the end of the
fil
Fermion Dipole Moments in Supersymmetric Models with Explicitly Broken R-parity
We present a simple analysis that allows us to extract the leading mass
dependence of the dipole moment of matter fermions that might be induced by new
physics. We present explicit results for the supersymmetric model with broken
R-parity as an illustration. We show that the extra contributions to the
electric dipole moment (edm) of fermions from R-parity violating interactions
can occur only at two loop level, contrary to claims in the literature. We
further find that unlike the generic lepto-quark models, the extra
contributions to the dipole moments of the leptons can only be enhanced by
m_b/m_l and not by m_t/m_l relative to the expectations in the Standard Model.
An interesting feature about this enhancement of these dipole moments is that
it does not involve unknown mixing angles. We then use experimental constraints
on the electric dipole moments of electron and neutron to obtain bounds on (the
imaginary part of) products of R-parity violating couplings, and show that
bounds claimed in the literature are too stringent by many orders of magnitude.Comment: 16 pages latex, 7 figure
Effects of polarisation on study of anomalous VVH interactions at a Linear Collider
We investigate the use of beam polarisation as well as final state
polarisation effects in probing the interaction of the Higgs boson with a pair
of heavy vector bosons in the process , where is
any light fermion. The sensitivity of the International Linear Collider (ILC)
operating at GeV, to such () couplings is examined
in a model independent way. The effects of ISR and beamstrahlung are discussed.Comment: To appear in the proceedings of 2007 International Linear Collider
Workshop (LCWS07 and ILC07), Hamburg, Germany, 30 May - 3 Jun 2007. 4 pages,
LaTeX, 1 eps figure. requires ilcws07.cls. included in submissio
Transverse Single Spin Asymmetries and Charmonium Production
We estimate transverse spin single spin asymmetry(TSSA) in the process
using color evaporation model of charmonium
production. We take into account transverse momentum dependent(TMD) evolution
of Sivers function and parton distribution function and show that the there is
a reduction in the asymmetry as compared to our earlier estimates wherein the
- evolution was implemented only through DGLAP evolution of unpolarized
gluon densities.Comment: Proceedings of Light Cone 2012, New Delhi, Indi
Single Spin Asymmetry in Charmonium Production
We present estimates of Single Spin Asymmetry (SSA) in the electroproduction
of taking into account the transverse momentum dependent (TMD)
evolution of the gluon Sivers function and using Color Evaporation Model of
charmonium production. We estimate SSA for JLab, HERMES, COMPASS and eRHIC
energies using recent parameters for the quark Sivers functions which are
fitted using an evolution kernel in which the perturbative part is resummed up
to next-to-leading logarithms (NLL) accuracy. We find that these SSAs are much
smaller as compared to our first estimates obtained using DGLAP evolution but
are comparable to our estimates obtained using TMD evolution where we had used
approximate analytical solution of the TMD evolution equation for the purpose.Comment: Conference proceedings of Light Cone 2014 at Raleigh, NC, USA. Talk
presented by Prof. Anuradha Misra. arXiv admin note: text overlap with
arXiv:1411.083
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
Single Production of Fourth Family Sneutrino via RPV Couplings at Linear Colliders
The single production of fourth family sneutrino via
R-parity violating interactions in electron-positron collisions has been
investigated. We study the decays of into different flavor
dilepton via R-parity violation. It is shown that R-parity
violating couplings down to 0.001 will be
reachable at future linear colliders which would provide better accuracy
comparing to the indirect measurements as complementary to the LHC results.Comment: 11 pages, 6 figure
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