4,616 research outputs found
Spin and model identification of Z' bosons at the LHC
Heavy resonances appearing in the clean Drell-Yan channel may be the first
new physics to be observed at the proton-proton CERN LHC. If a new resonance is
discovered at the LHC as a peak in the dilepton invariant mass distribution,
the characterization of its spin and couplings will proceed via measuring
production rates and angular distributions of the decay products. We discuss
the discrimination of the spin-1 of Z' representative models (Z'_{SSM},
Z'_{psi}, Z'_{eta}, Z'_{chi}, Z'_{LR}, and Z'_{ALR}) against the
Randall-Sundrum graviton resonance (spin-2) and a spin-0 resonance (sneutrino)
with the same mass and producing the same number of events under the observed
peak. To assess the range of the Z' mass where the spin determination can be
performed to a given confidence level, we focus on the angular distributions of
the Drell-Yan leptons, in particular we use as a basic observable an
angular-integrated center-edge asymmetry, A_{CE}. The spin of a heavy Z' gauge
boson can be established with A_{CE} up to M_{Z'} \simeq 3.0 TeV, for an
integrated luminosity of 100 fb^{-1}, or minimal number of events around 110.
We also examine the distinguishability of the considered Z' models from one
another, once the spin-1 has been established, using the total dilepton
production cross section. With some assumption, one might be able to
distinguish among these Z' models at 95% C.L. up to M_{Z'} \simeq 2.1 TeV.Comment: 18 pages, 6 figure
Spin-Orbit and Tensor Forces in Heavy-quark Light-quark Mesons: Implications of the New Ds state at 2.32 GeV
We consider the spectroscopy of heavy-quark light-quark mesons with a simple
model based on the non-relativistic reduction of vector and scalar exchange
between fermions. Four forces are induced: the spin-orbit forces on the light
and heavy quark spins, the tensor force, and a spin-spin force. If the vector
force is Coulombic, the spin-spin force is a contact interaction, and the
tensor force and spin-orbit force on the heavy quark to order are
directly proportional. As a result, just two independent parameters
characterize these perturbations. The measurement of the masses of three p-wave
states suffices to predict the mass of the fourth. This technique is applied to
the system, where the newly discovered state at 2.32 GeV provides the
third measured level, and to the system. The mixing of the two
p-wave states is reflected in their widths and provides additional constraints.
The resulting picture is at odds with previous expectations and raises new
puzzles.Comment: 6 pages, 1 figur
Properties of the Strange Axial Mesons in the Relativized Quark Model
We studied properties of the strange axial mesons in the relativized quark
model. We calculated the decay constant in the quark model and showed how
it can be used to extract the mixing angle
() from the weak decay . The ratio is the most sensitive
measurement and also the most reliable since the largest of the theoretical
uncertainties factor out. However the current bounds extracted from the
TPC/Two-Gamma collaboration measurements are rather weak: we typically obtain
at 68\% C.L. We also calculated the
strong OZI-allowed decays in the pseudoscalar emission model and the flux-tube
breaking model and extracted a mixing angle of . Our analysis also indicates that the heavy quark limit does not give a
good description of the strange mesons.Comment: Revised version to be published in Phys. Rev. D. Minor changes. Latex
file uses revtex version 3 and epsfig, 4 postcript figures are attached. The
full postcript version with embedded figures is available at
ftp://ftp.physics.carleton.ca/pub/theory/godfrey/ocipc9512.ps.
Phenomenological Study of Strong Decays of Heavy Hadrons in Heavy Quark Effective Theory
The application of the tensor formalism of the heavy quark effective theory
(HQET) at leading order to strong decays of heavy hadrons is presented.
Comparisons between experimental and theoretical predictions of ratios of decay
rates for B mesons, D mesons and kaons are given. The application of HQET to
strange mesons presents some encouraging results. The spin-flavor symmetry is
used to predict some decay rates that have not yet been measured.Comment: 10 page
Identification of Extra Neutral Gauge Bosons at the LHC Using b- and t-Quarks
New Neutral Gauge Bosons, Z' 's, are predicted by many models of physics
beyond the Standard Electroweak Theory. It is possible that a Z' would be
discovered early in the Large Hadron Collider program. The next step would be
to measure its properties to identify the underlying theory that gave rise to
the Z'. Heavy quarks have the unique property that they can be identified in
the final states. In this letter we demonstrate that measuring Z' decays to b-
and t-quark final states can act as an effective means of discriminating
between models with extra gauge bosons.Comment: 5 pages, 4 figures, references added and minor clarification
Isoscalar resonances with J^{PC}=1^{--} in e^+e^-annihilation
The analysis of the vector isoscalar excitations in the energy range between
1 and 2 GeV of the annihilation is presented for the final states
, , , and
. The effects of both the resonance mixing and the
successive opening of multiparticle channels, with the energy dependent partial
widths, are taken into account. The work extends our previous analysis
hep-ph/9609216 of the vector isovector excitations and is aimed to compare the
existing data with the predictions of the model. It is shown that
this hypothesis does not contradict the data.Comment: 16 pages, revtex, 6 ps figures. Clarifying remarks, a table, and
references are added. Accepted in Phys. Rev.
Production of the h_c and h_b and Implications for Quarkonium Spectroscopy
The recent observation of the h_c is an important test of QCD calculations
and provides constraints on models of quarkonium spectroscopy. In this
contribution I discuss some of these implications and describe methods to
search for the h_c and h_b via radiative transitions and other means.Comment: Talk presented at the 1st Meeting of the APS Topical Group on
Hadronic Physics (Fermilab, Oct 24-26, 2004), 4 pages, 1 figure, uses jpconf.
References adde
- …