274 research outputs found
Additional Soft Jets in Production at the Tevatron \pp Collider
A large fraction of top quark events in \pp collisions at 1.8\ \TeV will
contain additional soft hadronic jets from gluon bremsstrahlung off the quarks
and gluons in the hard processes \qq, gg \to \tt \to \bb \ww. These extra
jets can cause complications when attempting to reconstruct from the
invariant mass of combinations of final-state quarks and leptons. We show how
such soft radiation cannot be unambiguously associated with either
initial-state radiation or or with final-state radiation off the quarks.
The top quarks can radiate too, and in fact the pattern of radiation has a very
rich structure, which depends on the orientation of the final-state particles
with respect to each other and with respect to the beam. We calculate the full
radiation pattern of soft jets in the soft gluon approximation and compare with
several approximate forms which are characteristic of parton shower Monte
Carlos. The implications for top mass measurements are discussed.Comment: plain LaTeX, 13 pages plus 9 figures included as a separate uuencoded
file (or avail. from authors); DTP/94/60, UR-136
Exclusive Double Diffractive Events: Menu for LHC
Exclusive double diffractive events (EDDE) are considered in the framework of
the Regge-eikonal approach and perturbative calculations for "hard"
subprocesses. Total and differential cross-sections for processes are calculated.Comment: 18 pages, Latex 2.09, 6 postscript figures, references are adde
Non-factorizable corrections and effective field theories
We analyze the structure of higher-order radiative corrections for processes
with unstable particles. By subsequently integrating out the various scales
that are induced by the presence of unstable particles we obtain a hierarchy of
effective field theories. In the effective field theory framework the
separation of physically different effects is achieved naturally. In
particular, we automatically obtain a separation of factorizable and
non-factorizable corrections to all orders in perturbation theory. At one loop
this treatment is equivalent to the double-pole approximation (DPA) but
generalizes to higher orders and, at least in principle, to beyond the DPA. It
is known that one-loop non-factorizable corrections to invariant mass
distributions are suppressed at high energy. We study the mechanism of this
suppression and obtain estimates of higher-order non-factorizable corrections
at high energy.Comment: 45 page
events at the Next Linear Collider: colour structure of top signal and irreducible background
We examine the colour structure and charged particle yield for both the signal and the irreducible background processes contributing to
\eebbww\ production close to the \ttb\ threshold. The charged particle
multiplicity for the various components of the cross section is computed as a
function of several kinematic variables. Our study may have important
implications for recently proposed studies of interconnection phenomena in
\ttb\ production at high--energy collidersComment: 14 pages, Latex, 8 figures uuencoded, complete ps file available via
anonymous ftp at:
ftp://axpc.hep.phy.cam.ac.uk/disk$alpha1:[public.hep9514]CAVENDISH_9514.ps
http://www.hep.phy.cam.ac.uk/theory/papers/index.htm
Elastic and diffractive scattering at the LHC
Inspired by the new TOTEM data on elastic pp scattering at 13 TeV, we study the possibility to describe all the diffractive collider data (, , ) in a wide interval of energy (0.0625 to 13 TeV) in the framework of a two-channel eikonal model. We show that a satisfactory description can be achieved without an odd-signature (Odderon) exchange contribution. We consider the possible role of the QCD Odderon which may improve the description of Ï and discuss the importance of the odd-signature term if the amplitude were to exceed the black disc limit
5-dimensional Quantum Gravity Effects in Exclusive Double Diffractive Events
The experimentally measurable effects related to extra dimensional gravity in
a RS-type brane world are estimated. Two options of the RS framework (namely,
with small and large curvature) are considered. It is shown that both can be
detected by the joint experiment of the CMS and TOTEM Collaborations at the
LHC.Comment: 11 pages, 6 figures, 4 tables, acknowledgments are adde
Hadron multiplicity induced by top quark decays at the LHC
The average charged hadron multiplicities induced by top quark decays are
calculated in pQCD at LHC energies. Different modes of top production are
considered. Proposed measurements can be used as an additional test of pQCD
calculations independent on a fragmentation model.Comment: 12 pages, 12 figures, to be published elsewher
From the exclusive photoproduction of heavy quarkonia at HERA to the EDDE at TeVatron and LHC
Exclusive photoproduction of heavy quarkonia at HERA is analyzed in the
framework of the Regge-eikonal approach together with the nonrelativistic bound
state formalism. Total and differential cross-sections for the process
are calculated. The model predicts
cross-sections of Exclusive Double Diffractive Events (EDDE) at TeVatron and
LHC.Comment: 14 pages, 6 figures, reference is adde
Diffractive Processes at the LHC
We consider diffractive processes which can be measured at the LHC. Analysis
of diffractive events will give unique information about the high energy
asymptotics of hadron scattering. In semihard diffraction one may study the
partonic structure of the Pomeron. Central Exclusive Diffractive production
provides a possibility to investigate the new particles (Higgs bosons, SUSY
particles,...) in an exceptionally clean environment.Comment: 12 pages, To be published in the Proc. of the Gribov-75 Memorial
Workshop, Budapest, May 200
Extending the study of the Higgs sector at the LHC by proton tagging
We show that forward proton tagging may significantly enlarge the potential of studying the Higgs sector at the LHC. We concentrate on Higgs production via central exclusive diffractive processes (CEDP). Particular attention is paid to regions in the MSSM parameter space where the partial width of the Higgs boson decay into two gluons much exceeds the SM case; here the CEDP are found to have special advantages
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