4,663 research outputs found
Non-perturbative Renormalization of the Complete Basis of Four-fermion Operators and B-parameters
We present results on the B-parameters , and , at
, with the tree-level Clover action. The renormalization of the
complete basis of dimension-six four-fermion operators has been performed
non-perturbatively. Our results for and are in reasonable
agreement with those obtained with the (unimproved) Wilson action. This is not
the case for . We also discuss some subtleties arising from a
recently proposed modified definition of the B-parameters.Comment: Talk presented at Lattice '97, Edinburgh (UK), July 1997. LaTeX 3
pages, uses espcrc
Matrix Elements without Quark Masses on the Lattice
We introduce a new parameterization of four-fermion matrix elements which
does not involve quark masses and thus allows a reduction of systematic
uncertainties in physical amplitudes. As a result the apparent quadratic
dependence of e'/e on m_s is removed. To simplify the matching between lattice
and continuum renormalization schemes, we express our results in terms of
Renormalization Group Invariant B-parameters which are renormalization-scheme
and scale independent. As an application of our proposal, matrix elements of
DeltaI=3/2 and SUSY DeltaF=2 () four-fermion operators have been
computed.Comment: LATTICE99(Matrix Elements), 3 pages, 1 figure, BUHEP-99-2
Non-perturbative renormalization in kaon decays
We discuss the application of the MPSTV non-perturbative method \cite{NPM} to
the operators relevant to kaon decays. This enables us to reappraise the
long-standing question of the rule, which involves
power-divergent subtractions that cannot be evaluated in perturbation theory.
We also study the mixing with dimension-six operators and discuss its
implications to the chiral behaviour of the parameter.Comment: Talk presented at LATTICE96(improvement), LaTeX 3 pages, uses
espcrc2, 2 postscript figure
Non-perturbative renormalisation of four fermion operators and B-bar B mixing with Wilson fermions
We present new results for the renormalisation and subtraction constants for
the four fermion Delta F=2 operators, computed non-perturbatively in the RI-MOM
scheme (in the Landau gauge). From our preliminary analysis of the lattice data
at beta=6.45, for the B-bar B mixing bag-parameter we obtain B_B^{RGI} =
1.46(7)(1).Comment: 3 pages (4 figures), Lattice2002(heavyquark
Renormalization Group Invariant Matrix Elements of DS = 2 and DI = 3/2 Four-Fermion Operators without Quark Masses
We introduce a new parameterization of four-fermion operator matrix elements
which does not involve quark masses and thus allows a reduction of systematic
uncertainties. In order to simplify the matching between lattice and continuum
renormalization schemes, we express our results in terms of renormalization
group invariant B-parameters which are renormalization-scheme and scale
independent. As an application of our proposal, matrix elements of DI=3/2 and
SUSY DS =2 operators have been computed. The calculations have been performed
using the tree-level improved Clover lattice action at two different values of
the strong coupling constant (beta=6/g^2=6.0 and 6.2), in the quenched
approximation. Renormalization constants and mixing coefficients of lattice
operators have been obtained non-perturbatively. Using lowest order ChiPT, we
also obtain ^{NDR}_{I=2} = (0.11\pm 0.02) GeV^4 and <Pi Pi|
O_8|K >^{NDR}_{I=2} = (0.51\pm 0.05) GeV^4 at mu=2 GeV.Comment: LATEX, 17 pages, 1 figure include
Delta M_K and epsilon_K in SUSY at the Next-to-Leading order
We perform a Next-to-Leading order analysis of Delta S=2 processes beyond the
Standard Model. Combining the recently computed NLO anomalous dimensions and
the B parameters of the most general Delta S=2 effective Hamiltonian, we give
an analytic formula for Delta M_K and epsilon_K in terms of the Wilson
coefficients at the high energy scale. This expression can be used for any
extension of the Standard Model with new heavy particles. Using this result, we
consider gluino-mediated contributions to Delta S=2 transitions in general SUSY
models and provide an improved analysis of the constraints on off-diagonal mass
terms between the first two generations of down-type squarks. Finally, we
improve the constraints on R-violating couplings from Delta M_K and epsilon_K.Comment: 20 pages, 1 figure, uses JHEP.cls; the magic numbers in eq. (2.7),
previously given in the basis (13) of hep-ph/9711402, are now given in the
basis (2.3) of this work. All numerical results are unchange
Unveiling Neutrino Mixing and Leptonic CP Violation
We review the present understanding of neutrino masses and mixings,
discussing what are the unknowns in the three family oscillation scenario.
Despite the anticipated success coming from the planned long baseline neutrino
experiments in unraveling the leptonic mixing sector, there are two important
unknowns which may remain obscure: the mixing angle and the
CP-phase . The measurement of these two parameters has led us to
consider the combination of superbeams and neutrino factories as the key to
unveil the neutrino oscillation picture.Comment: Invited brief review, 18 pages, 6 figure
New interactions: past and future experiments
In this talk I will review the present status and future perspectives of some
popular extensions of the conventional three-neutrino oscillation scenario,
from a purely phenomenological point of view. For concreteness I will focus
only on three specific scenarios: non-standard neutrino interactions with
matters, models with extra sterile neutrinos, and neutrino decay and
decoherence.Comment: LaTeX file using jpconf class, 8 pages, 2 tables. Proceedings of the
"XXIII International Conference on Neutrino Physics and Astrophysics"
(Neutrino 08), Christchurch, New Zealand, May 25-31, 200
BK from the lattice with Wilson quarks
We report our results for the bag-parameter BK obtained from the quenched
simulations on the lattice with Wilson fermions at three values of the lattice
spacing. We implemented the method by which no subtraction of the mixing with
other four-fermion dS=2 operators is needed. Our final result, in terms of the
renormalisation group invariant bag-parameter, is BK = 0.96 +/- 0.10.Comment: 12 pages, 3 figures [version published in Eur.Phys.J.C
Inflammatory markers as prognostic factors of survival in patients affected by hepatocellular carcinoma undergoing transarterial chemoembolization
Transarterial chemoembolization (TACE) is a good choice for hepatocellular carcinoma (HCC) treatment when surgery and liver transplantation are not feasible. Few studies reported the value of prognostic factors influencing survival after chemoembolization. In this study, we evaluated whether preoperative inflammatory factors such as neutrophil to lymphocyte ratio and platelet to lymphocyte ratio affected our patient survival when affected by hepatocellular carcinoma. Methods. We retrospectively evaluated a total of 72 patients with hepatocellular carcinoma that underwent TACE. We enrolled patients with different etiopathogeneses of hepatitis and histologically proven HCC not suitable for surgery. The overall study population was dichotomized in two groups according to the median NLR value and was analyzed also according to other prognostic factors. Results. The global median overall survival (OS) was 28 months. The OS in patients with high NLR was statistically significantly shorter than that in patients with low NLR. The following pretreatment variables were significantly associated with the OS in univariate analyses: age, Child-Pugh score, BCLC stage, INR, and NLR. Pretreated high NLR was an independently unfavorable factor for OS. Conclusion. NLR could be considered a good prognostic factor of survival useful to stratify patients that could benefit from TACE treatment
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