1,472 research outputs found
Non-perturbative tests of continuum HQET through small-volume two-flavour QCD
We study the heavy quark mass dependence of selected observables constructed
from heavy-light meson correlation functions in small-volume two-flavour
lattice QCD after taking the continuum limit. The light quark mass is tuned to
zero, whereas the range of available heavy quark masses covers a region
extending from around the charm to beyond the bottom quark mass scale. This
allows entering the asymptotic mass-scaling regime as and
performing well-controlled extrapolations to the infinite-mass limit. Our
results are then compared to predictions obtained in the static limit of
continuum Heavy Quark Effective Theory (HQET), in order to verify
non-perturbatively that HQET is an effective theory of QCD. While in general we
observe a nice agreement at the few-% level, we find it to be less convincing
for the small-volume pseudoscalar decay constant when perturbative matching is
involved.Comment: 42 pages, 10 figures, 12 tables; JHEP styl
The breaking of the flavour permutational symmetry: Mass textures and the CKM matrix
Different ansaetze for the breaking of the flavour permutational symmetry
according to S(3)L X S(3)R in S(2)L X S(2) give different Hermitian mass
matrices of the same modified Fritzsch type, which differ in the symmetry
breaking pattern. In this work we obtain a clear and precise indication on the
preferred symmetry breaking scheme from a fit of the predicted theoretical Vckm
to the experimentally determined absolute values of the elements of the CKM
matrix. The preferred scheme leads to simple mass textures and allows us to
compute the CKM mixing matrix, the Jarlskog invariant J, and the three inner
angles of the unitarity triangle in terms of four quark mass ratios and only
one free parameter: the CP violating phase Phi. Excellent agreement with the
experimentally determined absolute values of the entries in the CKM matrix is
obtained for Phi = 90 deg. The corresponding computed values of the Jarlskog
invariant and the inner angles are J = 3.00 X 10^-5, alpha= 84 deg, beta= 24
deg and gamma =72 deg in very good agreement with current data on CP violation
in the neutral kaon-antikaon system and oscillations in the B-Bbar system.Comment: 21 pages, 1 fig. Content enlarged, references added and typos
corrected. To be published in Phys Rev
Implications of the KamLAND Measurement on the Lepton Flavor Mixing Matrix and the Neutrino Mass Matrix
We explore some important implications of the KamLAND measurment on the
lepton flavor mixing matrix and the neutrino mass matrix . The
model-independent constraints on nine matrix elements of are obtained to a
reasonable degree of accuracy. We find that nine two-zero textures of are
compatible with current experimental data, but two of them are only marginally
allowed. Instructive predictions are given for the absolute neutrino masses,
Majorana phases of CP violation, effective masses of the tritium beta decay and
neutrinoless double beta decay.Comment: RevTex 15 pages (4 PS figures included
Glueball production in hadron and nucleus collisions
We elaborate on the hypothesis that in high energy hadron hadron and nucleus
nucleus collisions the lowest mass glueballs are copiously produced from the
gluon rich environment especially at high energy density. We discuss the
particular glueball decay modes: and .Comment: 14 pages, six figure
and Expansion of the Weak Mixing Matrix
We perform a and expansion of the Cabibbo-Kobayashi- Maskawa
mixing matrix. Data suggest that the dominant parts of the Yukawa couplings are
factorizable into sets of numbers , , and ,
associated, respectively, with the left-handed doublets, the right-handed up
singlets, and the right- handed down singlets. The first order expansion is
consistent with Wolfenstein parameterization, which is an expansion in to third order. The mixing matrix elements in the present approach
are partitioned into factors determined by the relative orientations of , , and and the dynamics provided by the subdominant
mass matrices. A short discussion is given of some experimental support and a
generalized Fritzsch model is used to contrast our approach.Comment: A set of references has been added to ealier related wor
Prospects and status of quark mass renormalization in three-flavour QCD
We present the current status of a revised strategy to compute the running of
renormalized quark masses in QCD with three flavours of massless O(a) improved
Wilson quarks. The strategy employed uses the standard finite-size scaling
method in the Schr\"odinger functional and accommodates for the
non-perturbative scheme-switch which becomes necessary at intermediate
renormalized couplings as discussed in [arXiv:1411.7648].Comment: 7 pages, 3 figures, 1 table; Proceedings of the 33rd International
Symposium on Lattice Field Theory, 14-18 July 2015, Kobe, Japa
Towards a new determination of the QCD Lambda parameter from running couplings in the three-flavour theory
We review our new strategy and current status towards a high precision
computation of the Lambda parameter from three-flavour simulations in QCD. To
reach this goal we combine specific advantages of the Schr\"odinger functional
and gradient flow couplings.Comment: 7 pages, 3 figures; Proceedings of the 32nd International Symposium
on Lattice Field Theory; 23-28 June, 2014, Columbia University, New Yor
Democratic Neutrino Mixing and Radiative Corrections
The renormalization effect on a specific ansatz of lepton mass matrices,
arising naturally from the breaking of flavor democracy for charged leptons and
that of mass degeneracy for light neutrinos, is studied from a superhigh energy
scale M_0 \sim 10^{13} GeV to the electroweak scale in the framework of the
minimal supersymmetric standard model. We find that the democratic neutrino
mixing pattern obtained from this ansatz may in general be instable against
radiative corrections. With the help of similar flavor symmetries we prescribe
a slightly different scheme of lepton mass matrices at the scale M_0, from
which the democratic mixing pattern of lepton flavors can be achieved, after
radiative corrections, at the experimentally accessible scales.Comment: RevTex 8 pages. Phys. Rev. D (in printing
Embedding Phenomenological Quark-Lepton Mass Matrices into SU(5) Gauge Models
We construct phenomenological quark-lepton mass matrices based on S
permutation symmetry in a manner fully compatible with SU(5) grand unification.
The Higgs particles we need are {\bf 5}, {\bf 45} and their conjugates. The
model gives a charge 1/3 quark vs charged lepton mass relation, and also a
good fit to mass-mixing relations for the quark sector, as well as an
attractive mixing pattern for the lepton sector, explaining a large mixing
angle between and , and either large or small
mixing angle, depending on the choice of couplings, consistent
with the currently accepted solutions to the solar neutrino problem.Comment: 12 pages, LaTex file, no figure
Hierarchy and Up-Down Parallelism of Quark Mass Matrices
In view of the quark mass hierarchy and in the assumption of the up-down
parallelism, we derive two phenomenologically-favored patterns of Hermitian
quark mass matrices from the quark flavor mixing matrix. We compare one of them
with two existing {\it Anstze} proposed by Rosner and Worah and by
Roberts {\it et al}, and find that only the latter is consistent with the
present experimental data.Comment: RevTex 9 pages. Accepted for publication in Phys. Rev.
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