1,404 research outputs found
(Pseudo)Scalar Charmonium in Finite Temperature QCD
The hadronic parameters of pseudoscalar () and scalar ()
charmonium are determined at finite temperature from Hilbert moment QCD sum
rules. These parameters are the hadron mass, leptonic decay constant, total
width, and continuum threshold (). Results for in both channels
indicate that starts approximately constant, and then it decreases
monotonically with increasing until it reaches the QCD threshold, , at a critical temperature T = T_c \simeq 180 \; \mbox{MeV}
interpreted as the deconfinement temperature. The other hadronic parameters
behave qualitatively similarly to those of the , as determined in this
same framework. The hadron mass is essentially constant, the total width is
initially independent of T, and after it begins to increase
with increasing up to for
(), and subsequently it decreases sharply up to , for (), beyond which the sum rules are no
longer valid. The decay constant of at first remains basically flat up
to , then it starts to decrease up to , and finally it increases sharply with increasing . In the case of
the decay constant does not change up to where
it begins a gentle increase up to beyond which it
increases dramatically with increasing . This behaviour contrasts with that
of light-light and heavy-light quark systems, and it suggests the survival of
the and the states beyond the critical temperature, as
already found for the from similar QCD sum rules. These conclusions
are very stable against changes in the critical temperature in the wide range
T_c = 180 - 260 \; \mbox{MeV}.Comment: 12 pages, 5 figures. A wide range of critical temperatures has been
considered. No qualitative changes to the conclusion
Charm-quark mass from weighted finite energy QCD sum rules
The running charm-quark mass in the scheme is determined from
weighted finite energy QCD sum rules (FESR) involving the vector current
correlator. Only the short distance expansion of this correlator is used,
together with integration kernels (weights) involving positive powers of ,
the squared energy. The optimal kernels are found to be a simple {\it pinched}
kernel, and polynomials of the Legendre type. The former kernel reduces
potential duality violations near the real axis in the complex s-plane, and the
latter allows to extend the analysis to energy regions beyond the end point of
the data. These kernels, together with the high energy expansion of the
correlator, weigh the experimental and theoretical information differently from
e.g. inverse moments FESR. Current, state of the art results for the vector
correlator up to four-loop order in perturbative QCD are used in the FESR,
together with the latest experimental data. The integration in the complex
s-plane is performed using three different methods, fixed order perturbation
theory (FOPT), contour improved perturbation theory (CIPT), and a fixed
renormalization scale (FMUPT). The final result is , in a wide region of stability against changes in the
integration radius in the complex s-plane.Comment: A short discussion on convergence issues has been added at the end of
the pape
Spatial Legality, Due Process, and Choice of Law in Human Rights Litigation Under U.S. State Law
Framing the topic of this symposium as “Human Rights Litigation in State Courts and Under State Law” effectively orients the discussion around the rights of plaintiffs from the outset, the central question being whether they have enforceable rights in U.S. state courts under state law. Standing in the way are various legal doctrines. In broad strokes, the relevant questions become: Which doctrines do, or should, either facilitate or obstruct human rights litigation in U.S. state courts and under state law? How are courts applying these doctrines? How should courts apply these doctrines?
Many of the doctrines that potentially stand in the way of human rights claims in state court and under state law reflect the interests of states — including U.S. states, the United States, and foreign nations. State-centered doctrines like sovereign interference, comity, preemption, governmental interest analysis, the political question doctrine, and other doctrines deferential to the political branches threaten to block human rights litigation in state courts and under state law. The discussion thus tends to boil down to human rights versus states — or, perhaps more accurately, plaintiffs’ rights versus legal doctrines that capture some non-human rights interest of states.
This contribution aims to add another rights dimension to this rapidly evolving doctrinal and normative puzzle by reorienting the discussion around the rights of defendants. More specifically, we ask whether there are defendants’ rights that may counterbalance plaintiffs’ rights in some situations. We believe there are, and that these rights can and should inform how courts decide human rights cases in state courts and under state law. Because our primary concern is choice of law as opposed to choice of forum, we focus principally on issues related to the application of state law rather than on issues related to state courts entertaining suit. As to the choice of law, we use the concept of what we will refer to as “spatial legality” to identify and frame two main rights: the right to fair notice of the law, and the right to compliance with the law. We then apply these rights through the Due Process Clause to show how they can and should influence human rights litigation under state law. First, we conclude that even if personal jurisdiction exists over a defendant, if the conduct giving rise to the suit exhibits no jurisdictional nexus to the United States, application of purely U.S. law — like state tort law — may violate defendants’ rights to fair notice of the law. Second, we suggest that where purely U.S. law — like state tort law — prohibits or creates liability for conduct compelled or required under foreign law in the place where the conduct occurs, defendants may have a due process objection because compliance with the law is impossible. Finally, we argue that both of these objections largely vanish where the U.S. law sought to be applied to foreign conduct implements an international law that imposes liability
Spatial Legality, Due Process, and Choice of Law in Human Rights Litigation Under U.S. State Law
Remarks on the hadronic matrix elements relevant to the SUSY K-Kbar mixing amplitude
We compute the 1-loop chiral corrections to the bag parameters which are
needed for the discussion of the SUSY K-Kbar mixing problem in both finite and
infinite volume. We then show how the bag parameters can be combined among
themselves and with some auxiliary quantities and thus sensibly reduce the
systematic errors due to chiral extrapolations as well as those due to finite
volume artefacts present in the results obtained from lattice QCD. We also show
that in some cases these advantages remain as such even after including the
2-loop chiral corrections. Similar discussion is also made for the K --> pi
electro-weak penguin operators.Comment: 13 pages, 3 figures [added 1 reference and a discussion about the
impact of the NNLO chiral corrections to the "golden ratios" (c.f. Sec.6)
Cusps in K_L --> 3 pi decays
The pion mass difference generates a pronounced cusp in K --> 3 pi decays,
the strength of which is related to the pi pi S-wave scattering lengths. We
apply an effective field theory framework developed earlier to evaluate the
amplitudes for K_L --> 3 pi decays in a systematic manner, where the strictures
imposed by analyticity and unitarity are respected automatically. The
amplitudes for the decay eta --> 3 pi are also given.Comment: 15 pages, 3 figures, uses Elsevier styl
The isospin symmetry breaking effects in decays
The Fermi-Watson theorem is generalized to the case of two coupled channels
with different masses and applied to final state interaction in
decays. The impact of considered effect on the phase of the scattering
is estimated and shown that it can be crucial for scattering lengths extraction
from experimental data on decays
K+ -> pi+ nu nu(bar) and FCNC from non-universal Z' bosons
Motivated by the E787 and E949 result for K+ -> pi+ nu nu(bar) we examine the
effects of a new non-universal right-handed Z' boson on flavor changing
processes. We place bounds on the tree-level FCNC from K-K(bar) and B-B(bar)
mixing as well as from the observed CP violation in kaon decay. We discuss the
implications for K -> pi nu nu(bar), B -> X nu nu(bar) and B -> tau+ tau-. We
find that existing bounds allow substantial enhancements in the K+ -> pi+ nu
nu(bar) rate, particularly through a new one-loop Z' penguin operator.Comment: Typos corrected, references added, version to appear in PR
K -> 3 pi Final State Interactions at NLO in CHPT and Cabibbo's Proposal to Measure a_0-a_2
We present the analytical results for the K -> 3 pi final state interactions
at next-to-leading order (NLO) in CHPT. We also study the recent Cabibbo's
proposal to measure the pi-pi scattering lenghts combination a_0-a_2 from the
cusp effect in the pi^0-pi^0 energy spectrum at threshold for K^+ -> pi^0 pi^0
pi^+ and K_L -> pi^0 pi^0 pi^0$, and give the relevant formulas to describe it
at NLO. For that, we use the NLO CHPT expression to fit the real part of K -> 3
pi to data while the pi-pi scattering lenghts are treated non-perturbatively.
Using them, we make a quantitative estimate of the theoretical uncertaintity of
the a_0-a_2 determination at NLO in our approach and obtain that it is not
smaller than 5 % if added quadratically and 7 % if linearly for K^+ -> pi^0
pi^0 pi^+. One gets similar theoretical uncertainties if the neutral K_L ->
pi^0 pi^0 pi^0 decay data below threshold are used instead. For this decay,
there are very large theoretical uncertainties above threshold due to
cancellations and data above threshold cannot be used to get the scattering
lenghts. All the numbers we present are in the isospin limit apart of two-pion
phase space factors which are physical. We compare our results for the cusp
effect with Cabibbo and Isidori's results and discuss the differences and
agreements.
We also comment on the apperance of the singularity at the K -> 3 pi
pseudo-threshold s=(m_K-m_pi)^2 in the discontinuity that defines the cusp.Comment: 31 pages, 8 figures. v2=v3 Added the full contributions to the cusp
from the real part of the discontinuity. v4 Improved text. Matches published
versio
Pion mass dependence of the semileptonic scalar form factor within finite volume
We calculate the scalar semileptonic kaon decay in finite volume at the
momentum transfer , using chiral perturbation
theory. At first we obtain the hadronic matrix element to be calculated in
finite volume. We then evaluate the finite size effects for two volumes with and and find that the difference between the finite
volume corrections of the two volumes are larger than the difference as quoted
in \cite{Boyle2007a}. It appears then that the pion masses used for the scalar
form factor in ChPT are large which result in large finite volume corrections.
If appropriate values for pion mass are used, we believe that the finite size
effects estimated in this paper can be useful for Lattice data to extrapolate
at large lattice size.Comment: 19 pages, 5 figures, accepted for publication in EPJ
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