1,879 research outputs found
Free Meson Spectral Functions on the Lattice
We present results from an analytic calculation of thermal meson spectral
functions in the infinite temperature (free field) limit. We compare spectral
functions for various lattice fermion formulations used at present in studies
of in-medium properties of hadrons based on the maximum entropy method (MEM).
In particular, we will present a new calculation of spectral functions
performed with extended quark sources.Comment: 3 pages, Lattice2003(nonzero
Probing Higgs-sector CP Violation at a Photon Collider
In this review we demonstrate physics potential of a photon linear collider
by studying the neutral Higgs-boson sector of the MSSM in which interesting
CP-violating Higgs mixing could arise via radiative corrections.Comment: 18 pages, 8 figures, 1 table, invited article by Modern Physics
Letters A (review section), added reference
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
Charged Higgs Production in Association with W Boson at Photon Colliders
It is important to explore the Higgs sector in order to identify the model
beyond the standard model. We study the charged Higgs production in the
mode of a linear collider (LC) with 1000 GeV center of mass
energy. We show that the cross sections for the
processes can be significantly enhanced in the two Higgs doublet model (THDM).
The cross section can reach 0.1 - 100 fb which is comparable to other charged
Higgs boson production processes at a photon collider. While for other
processes the cross sections are too small for GeV, fb can be expected in the processes for
GeV when GeV. Therefore, even if the charged
Higgs bosons can not be detected at the Large Hadron Collider (LHC), and even
if the charged Higgs bosons are too heavy to be detected in other charged Higgs
boson production processes at the LC, it may be possible to detect them in this
process.Comment: To appear in the proceedings of 2005 International Linear Collider
Workshop (LCWS 2005), Stanford, California, 18-22 Mar 200
Excited D-branes and Supergravity Solutions
We investigate the general solution with the symmetry ISO(1,p)xSO(9-p) of
Type II supergravity (the three-parameter solution) from the viewpoint of the
superstring theory. We find that one of the three parameters (c_1) is closely
related to the ``dilaton charge'' and the appearance of the dilaton charge is a
consequence of deformations of the boundary condition from that of the boundary
state for BPS D-branes. We give three examples of the deformed D-branes by
considering the tachyon condensation from systems of D-\bar{D}p-branes,
unstable D9-branes and unstable D-instantons to the BPS saturated Dp-branes,
respectively. We argue that the deformed systems are generally regarded as
tachyonic and/or massive excitations of the open strings on Dp-\bar{D}p-brane
systems.Comment: 29 pages, 6 figures, LaTeX2e, typos corrected, references adde
Secondary phi meson peak as an indicator of QCD phase transition in ultrarelativistic heavy ion collisions
In a previous paper, we have shown that a double phi peak structure appears
in the dilepton invariant mass spectrum if a first order QCD phase transition
occurs in ultrarelativistic heavy ion collisions. Furthermore, the transition
temperature can be determined from the transverse momentum distribution of the
low mass phi peak. In this work, we extend the study to the case that a smooth
crossover occurs in the quark-gluon plasma to the hadronic matter transition.
We find that the double phi peak structure still exists in the dilepton
spectrum and thus remains a viable signal for the formation of the quark-gluon
plasma in ultrarelativistic heavy ion collisions.Comment: 8 pages, 9 uuencoded postscript figures included, Latex, LBL-3572
Studying possible CP-violating Higgs couplings through top-quark pair productions at muon colliders
We study possible anomalous CP-violating Higgs couplings to mu mu-bar and t
t-bar fully model-independent way through top-quark pair productions at muon
colliders. Assuming additional non-standard neutral Higgs bosons, whose
couplings with top-quark and muon are expressed in the most general covariant
form, we carry out analyses of effects which they are expected to produce via
CP-violating asymmetries and also the optimal-observable (OO) procedure under
longitudinal and transverse muon polarizations. We find the measurement of the
asymmetry for longitudinal beam polarization could be useful to catch some
signal of CP violation, and an OO analysis might also be useful if we could
reduce the number of unknown parameters with a help of other experiments and if
the size of the parameters is at least O(1) ~ O(10).Comment: Final version (to appear in JHEP
Stringy Derivation of Nahm Construction of Monopoles
We derive the Nahm construction of monopoles from exact tachyon condensation
on unstable D-branes. The Dirac operator used in the Nahm construction is
identified with the tachyon profile in our D-brane approach, and we provide
physical interpretation of the procedures Nahm gave. Crucial is the
introduction of infinite number of brane-antibranes from which arbitrary
D-brane can be constrcuted, exhibitting a unified view of various D-branes. We
explicitly show the equivalence of the D3-brane boundary state with the
monopole profile and the D1-brane boundary state with the Nahm data as
transverse scalars.Comment: 18 pages, 4 eps figures, JHEP style, comments about low energy limits
added, references adde
Equation of state of strongly coupled Hamiltonian lattice QCD at finite density
We calculate the equation of state of strongly coupled Hamiltonian lattice
QCD at finite density by constructing a solution to the equation of motion
corresponding to an effective Hamiltonian using Wilson fermions. We find that
up to and beyond the chiral symmetry restoration density the pressure of the
quark Fermi sea can be negative indicating its mechanical instability. This
result is in qualitative agreement with continuum models and should be
verifiable by future numerical simulations.Comment: 14 pages, 2 EPS figures. Revised version - added discussion on the
equation of stat
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