3,192 research outputs found
The surgery obstruction groups of the infinite dihedral group
This paper computes the quadratic Witt groups (the Wall L-groups) of the
polynomial ring Z[t] and the integral group ring of the infinite dihedral
group, with various involutions. We show that some of these groups are infinite
direct sums of cyclic groups of order 2 and 4. The techniques used are
quadratic linking forms over Z[t] and Arf invariants.Comment: Published by Geometry and Topology at
http://www.maths.warwick.ac.uk/gt/GTVol8/paper29.abs.htm
Solving the SUSY CP problem with flavor breaking F-terms
Supersymmetric flavor models for the radiative generation of fermion masses
offer an alternative way to solve the SUSY-CP problem. We assume that the
supersymmetric theory is flavor and CP conserving. CP violating phases are
associated to the vacuum expectation values of flavor violating susy-breaking
fields. As a consequence, phases appear at tree level only in the soft
supersymmetry breaking matrices. Using a U(2) flavor model as an example we
show that it is possible to generate radiatively the first and second
generation of quark masses and mixings as well as the CKM CP phase. The
one-loop supersymmetric contributions to EDMs are automatically zero since all
the relevant parameters in the lagrangian are flavor conserving and as a
consequence real. The size of the flavor and CP mixing in the susy breaking
sector is mostly determined by the fermion mass ratios and CKM elements. We
calculate the contributions to epsilon, epsilon^{prime} and to the CP
asymmetries in the B decays to psi Ks, phi Ks, eta^{\prime} Ks and Xs gamma. We
analyze a case study with maximal predictivity in the fermion sector. For this
worst case scenario the measurements of Delta mK, Delta mB and epsilon
constrain the model requiring extremely heavy squark spectra.Comment: 21 pages, RevTex
Probing New Physics via an Angular Analysis of B --> V1 V2 decays
We show that an angular analysis of B --> V1 V2 decays yields numerous tests
for new physics in the decay amplitudes. Unlike direct CP asymmetries, many of
these new-physics observables are nonzero even if the strong phase differences
vanish. For certain observables, neither time-dependent measurements nor
tagging is necessary. Should a signal for new physics be found, one can place a
lower limit on the size of the new-physics parameters, as well as on their
effect on the measurement of the phase of B0--Bbar0 mixing.Comment: 9 pages, plain latex, no figures. Title modified slightly. Paragraph
added about viability of method. Conclusions unchanged. To be published in
Europhysics Letter
Is there New Physics in B Decays ?
Rare decays of the meson are sensitive to new physics effects. Several
experimental results on these decays have been difficult to understand within
the standard model (SM) though more precise measurements and a better
understanding of SM theory predictions are needed before any firm conclusions
can be drawn. In this talk we try to understand the present data assuming the
presence of new physics. We find that the data points to new physics of an
extended Higgs sector and we present a two higgs doublet model with a 2-3
flavor symmetry in the down type quark sector that can explain the deviations
from standard model reported in several rare B decays.Comment: 8 pages, Talk presented at Theory Canada II, Perimeter Institute,
Waterloo, Canada. New references added and update
Topological rigidity and H_1-negative involutions on tori
We prove there is only one involution (up to conjugacy) on the n-torus which
acts as on the first homology group when is of the form
, is of the form , or is less than . In all other cases we prove
there are infinitely many such involutions up to conjugacy, but each of them
has exactly fixed points and is conjugate to a smooth involution. The key
technical point is that we completely compute the equivariant structure set for
the corresponding crystallographic group action on in terms of
the Cappell -groups arising from its infinite dihedral
subgroups. We give a complete analysis of equivariant topological rigidity for
this family of groups.Comment: 50 pages, to appear in Geometry & Topolog
Aspects Of Heavy Quark Theory
Recent achievements in the heavy quark theory are critically reviewed. The
emphasis is put on those aspects which either did not attract enough attention
or cause heated debates in the current literature. Among other topics we
discuss (i) basic parameters of the heavy quark theory; (ii) a class of exact
QCD inequalities; (iii) new heavy quark sum rules; (iv) virial theorem; (v)
applications (|V_cb| from the total semileptonic width and from the B->D*
transition at zero recoil). In some instances new derivations of the previously
known results are given, or new aspects addressed. In particular, we dwell on
the exact QCD inequalities. Furthermore, a toy model is considered that may
shed light on the controversy regarding the value of the kinetic energy of
heavy quarks obtained by different methods.Comment: 67 pages, 6 Figures; plain LaTeX. Changes: Some equations in Sect.4
related to spin-nonsinglet sum rules are corrected. The references are
updated
Constraints on charged Higgs bosons from D(s)+- -> mu+- nu and D(s)+- -> tau+- nu
The decays D(s)+- -> mu+- nu and D(s)+- -> tau+- nu have traditionally been
used to measure the D(s)+- meson decay constant f_D(s). Recent measurements at
CLEO-c and the B factories suggest a branching ratio for both decays somewhat
higher than the Standard Model prediction using f_D(s) from unquenched lattice
calculations. The charged Higgs boson (H+-) in the Two Higgs Doublet Model
(Type II) would also mediate these decays, but any sizeable contribution from
H+- can only suppress the branching ratios and consequently is now slightly
disfavoured. It is shown that constraints on the parameters tan(beta) and m_H+-
from such decays can be competitive with and complementary to analogous
constraints derived from the leptonic meson decays B+- -> tau+- nu_tau and K+-
-> mu+- nu_mu, especially if lattice calculations eventually prefer f_D(s) <
250 MeV.Comment: 18 pages, 4 figure
Inclusive production in B decays and the Enhancement due to charged technipions
The new contributions to the charmless B decay
from the unit-charged technipions and are estimated.
The technipions can provide a large enhancement to the inclusive branching
ratio: for
and when the effect of QCD gluon anomaly is also
taken into account. The new physics effect is essential to interpret the CLEO
data.Comment: Latex file, 7 pages with two EPS figure
Measuring V_ub and probing SUSY with double ratios of purely leptonic decays of B and D mesons
The experimental prospects for precise measurements of the leptonic decays
B_u -> tau nu / mu nu, B_s -> mu+ mu-, D -> mu nu and D_s -> mu nu / tau nu are
very promising. Double ratios involving four of these decays can be defined in
which the dependence on the values of the decay constants is essentially
eliminated, thus enabling complementary measurements of the CKM matrix element
V_ub with a small theoretical error. We quantify the experimental error in a
possible future measurement of |V_ub| using this approach, and show that it is
competitive with the anticipated precision from the conventional approaches.
Moreover, it is shown that such double ratios can be more effective than the
individual leptonic decays as a probe of the parameter space of supersymmetric
models. We emphasize that the double ratios have the advantage of using |V_ub|
as an input parameter (for which there is experimental information), while the
individual decays have an uncertainty from the decay constants (e.g. f_B_s),
and hence a reliance on theoretical techniques such as lattice QCD.Comment: 21 pages, 4 figure
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