1,934 research outputs found
Testing Explanations of the Polarization Puzzle
(\btos) is three separate decays, one for each polarization
of the final-state vector mesons (one longitudinal, two transverse). It is
observed that the fraction of transverse decays, \fT, and the fraction of
longitudinal decays, \fL, are roughly equal: \fTfL \simeq 1, in opposition
to the naive expectation that \fT \ll \fL. If one requires a single
explanation of all polarization puzzles, two possibilities remain within the
standard model: penguin annihilation and rescattering. In this paper we examine
the predictions of these two explanations for \fTfL in \btod decays. In decays, only \bd \to \rho^0\rho^0 can possibly exhibit a large
\fTfL. In B decays related by U-spin, we find two promising possibilities:
(i) (\btos) and B^+ \to \Kbar^{*0} K^{*+} (\btod)
and (ii) \bs \to K^{*0} \Kbar^{*0} (\btos) and \bd \to \Kbar^{*0} K^{*0}
(\btod). The measurement of \fTfL in these pairs of decays will allow us to
test penguin annihilation and rescattering. Finally, it is possible to
distinguish penguin annihilation from rescattering by performing a
time-dependent angular analysis of \bd \to \Kbar^{*0} K^{*0}.Comment: 15 pages, 2 figures. Added reference and PACS numbers. To appear in
PR
Study of Polarization in B -> VT Decays
In this paper, we examine B -> VT decays (V is a vector and T is a tensor
meson), whose final-state particles can have transverse or longitudinal
polarization. Measurements have been made of B -> \phi K_2^*, and it is found
that fT/fL is small, where fT (fL) is the fraction of transverse (longitudinal)
decays. We find that the standard model (SM) naively predicts that fT/fL << 1.
The two extensions of the naive SM which have been proposed to explain the
large fT/fL in B -> \phi K^* -- penguin annihilation and rescattering -- make
no firm predictions for the polarization in B -> \phi K_2^*. The two
new-physics scenarios, which explain the data in B -> \pi K and the \phi (\rho)
K^* polarization measurements, can reproduce the fT/fL data in B -> \phi K_2^*
only if the B -> T form factors obey a certain hierarchy. Finally, we present
the general angular analysis which can be used to get helicity information
using two- and three-body decays.Comment: 15 pages, latex, 3 figures (enclosed), several changes made,
conclusions unchanged, publication info adde
Constraining anomalous Higgs boson couplings to virtual photons
We present a study of Higgs boson production in vector boson fusion and in
association with a vector boson and its decay to two vector bosons, with a
focus on the treatment of virtual loops and virtual photons. Our analysis is
performed with the JHU generator framework. Comparisons are made to several
other frameworks, and the results are expressed in terms of an effective field
theory. New features of this study include a proposal on how to handle
singularities involving Higgs boson decays to light fermions via photons,
calculation of the partial Higgs boson width in the presence of anomalous
couplings to photons, a comparison of the next-to-leading-order electroweak
corrections to effects from effective couplings, and phenomenological
observations regarding the special role of intermediate photons in analysis of
LHC data in the effective field theory framework. Some of these features are
illustrated with projections for experimental measurements with the full LHC
and HL-LHC datasets.Comment: 32 pages, 14 figure
Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV
Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio
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