2,571 research outputs found

### The Charm Quark on the Lattice

We formulate lattice fermions in a way that encompasses Wilson fermions as
well as the static and non-relativistic approximations. In particular, we treat
$m_qa$ systematically ($m_q$ is the fermion mass) showing how to understand the
Wilson action as an effective action for systems with \vek{p}\ll m_q. The
results show how to extract matrix elements and the spectrum from simulations
with $m_qa\approx1$, which is relevant for the charm quark.Comment: 4 pages LaTeX using espcrc2.sty and epsf.sty. FERMILAB-CONF-92/329-

### The Isgur-Wise Limit on the Lattice

We construct the Isgur-Wise limit of QCD in a form appropriate to lattice
gauge theory techniques. The formulation permits a calculation of heavy quark
processes even when the momentum transfers are much larger than the inverse
lattice spacing. Applications include semi-leptonic heavy quark decay and
scattering processes, including the computation of the nonperturbative part of
the Isgur-Wise universal function.Comment: Talk given at the 1992 International Lattice Gauge Theory Conference
("Lattice '92"), Amsterdam, 4 pages, in postscrip

### Color-Coulomb Force Calculated from Lattice Coulomb Hamiltonian

The static color-Coulomb potential is calculated as the solution of a
non-linear integral equation. This equation has been derived recently as a
self-consistency condition which arises in the Coulomb Hamiltonian formulation
of lattice gauge theory when the restriction to the interior of the Gribov
horizon is implemented. The potential obtained is in qualitative agreement with
expectations, being Coulombic with logarithmic corrections at short range and
confining at long range. The values obtained for the string tension and
$\Lambda_{\overline{MS}}$ are in semi-quantitative agreement with lattice Monte
Carlo and phenomenological determinations.Comment: 4 pages (including 1 figure); (latex using espcrc2.sty). Talk
presented at LATTICE96(poster

### Investigation of Quark-Antiquark Interaction Properties using Leading Particle Measurements in e+e- Annihilation

Measurements of heavy quark production in electron-positron collisions are
used to analyse the strong interactions between quarks and anti-quarks. A
scaling behaviour is observed in distributions of the rapidity change of D*,
B*, and B mesons. From these distributions information is obtained on the
hadron formation time, effective quark masses, and the potential between
quark-antiquark pairs. Predictions for fragmentation functions are presented.Comment: 10 pages, 4 figures, fig.2 references added, revised version accepted
by Physics Letters

### Can a light technipion be discovered at the Tevatron if it decays to two gluons?

In multiscale and topcolor-assisted models of walking technicolor, light,
spin-one technihadrons can exist with masses of a few hundred GeV; they are
expected to decay as rho_T -> W pi_T. For technirho masses ~200 GeV and
technipion masses ~100 GeV, the process pbar p -> rho_T -> W pi_T has a cross
section of about a picobarn at the Tevatron. We demonstrate the detectability
of this process with simulations appropriate to Run II conditions, for the
challenging case where the technipion decays dominantly into two gluons.Comment: 11 pages, LaTeX, including figure

### Low-Scale Technicolor at the Tevatron and LHC

The Tevatron experiments CDF and DO are close to making definitive statements
about the technicolor discovery mode rho_T -> W pi_T for M(rho_T) <~ 230 GeV
and M(pi_T) <~ 125 GeV. We propose new incisive tests for this mode and
searches for others that may be feasible at the Tevatron and certainly are at
the LHC. The other searches include two long discussed, namely, omega_T ->
gamma pi_T and l+l-, and a new one -- for the I^G J^{PC} = 1^- 1^{++} partner,
a_T, of the rho_T. Adopting the argument that the technicolor contribution to S
is reduced if M(a_T) is near M(rho_T), we enumerate important a_T decays and
estimate production rates at the colliders.Comment: Version to be published in Physics Letters B. Revised to reflect
latest CDF search for technirho to W technipi and new studies of the LHC's
reach for low-scale technicolo

### Variational calculation of heavy-light meson properties

We present a new method for the study of heavy-light mesons in the static
approximation of lattice QCD which is optimally effective in isolating ground
and excited states. With ``MOST'' (Maximal Operator Smearing Technique), the
heavy quark is smeared at all possible positions relative to the light quark,
subject to the constraint of cubic symmetry. With correlation functions
constructed using this set as a variational basis, eigenstates of the transfer
matrix are projected out at very small time separations, where statistical
errors are small. We illustrate the utility of the method with preliminary
results for the meson decay constant $f_{B}^{\rm stat}$, binding energies and
wave functions of the lowest states. The method produces dynamically-improved
interpolating fields which can be used for matrix element calculations.Comment: 3pages, uuencode-compressed-tar Postscript file. (160 kbytes),
preprint number uk/93-0

### Charmonium levels near threshold and the narrow state X(3872) \to \pi^{+}\pi^{-}\jpsi

We explore the influence of open-charm channels on charmonium properties, and
profile the 1:3D2, 1:3D3 and 2:1P1 charmonium candidates for X(3872). The
favored candidates, the 1:3D2 and 1:3D3 levels, both have prominent radiative
decays. The 1:3D2 might be visible in the $D^{0}\bar{D}^{*0}$ channel, while
the dominant decay of the 1:3D3 state should be into $D\bar{D}$. We propose
that additional discrete charmonium levels can be discovered as narrow
resonances of charmed and anticharmed mesons.Comment: 8 pages, 6 figures, uses RevTeX and boxedeps; few transcription
errors corrected in Tables IV and VI, three entries added in Table V, updated
references. Version to appear in Phys. Rev.

### Structural Properties of the Lattice Heavy Quark Effective Theory

We discuss two related aspects of the lattice version of the heavy quark
effective theory (HQET). They are the effects of heavy quark modes with large
momenta, near the boundary of the Brillouin zone, and the renormalization of
the lattice HQET. We argue that even though large momentum modes are present,
their contributions to heavy-light bound states and perturbative loop integrals
are dynamically suppressed and vanish in the continuum limit. We also discuss a
new feature of the renormalization of the lattice HQET not present in the
continuum theory, namely that the classical velocity is finitely renormalized.Comment: 4 pages; postscript; no figures; Talk at Lattice `94 (Bielefeld

### Strong Dynamics at the Muon Collider: Working Group Report

New strong dynamics at the energy scale ~ 1 TeV is an attractive and elegant
theoretical ansatz for the origin of electroweak symmetry breaking. We review
here the theoretical models for strong dynamics, particularly, technicolor
theories and their low energy signatures. We emphasize that the fantastic beam
energy resolution (sigma_E/E ~10^{-4}) expected at the first muon collider
(sqrt{s} = 100-500 GeV) allows the possibility of resolving some
extraordinarily narrow technihadron resonances and, Higgs-like techniscalars
produced in the s-channel. Investigating indirect probes for strong dynamics
such as search for muon compositeness, we find that the muon colliders provide
unparallel reaches. A big muon collider (sqrt{s} =3-4 TeV) would be a
remarkable facility to study heavy technicolor particles such as the topcolor
Z', to probe the dynamics underlying fermion masses and mixings and to fully
explore the strongly interacting electroweak sector.Comment: 19 pages, 10 figures, uses aipproc. Plenary talk at the Fermilab
Workshop on Physics at the First Muon Collider and at the Front End of a Muon
Collider, November 199

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