6,550 research outputs found
Gauge mediation with heavy doublet superparticles
It is challenging for supersymmetry if the 125 GeV Higgs boson is confirmed
by the LHC. In the case of small squark mixing it is inevitable to introduce
heavy top squarks to lift the Higgs mass that is hard to be produced by the
LHC. Here we consider the possibility that in gauge mediation the
superparticles belonging to SU(2) doublets are much heavier than those do not
carry the SU(2) quantum numbers. Under the assumption not only the Higgs mass
can be large enough but also there are light right handed top squarks below the
TeV scale that can be observed in future.Comment: 10pages, no figures, accepted for publication in Phys. Rev.
Initial state radiation effects in inclusive production at B factories
Based on Monte Carlo techniques, we analyze the initial state radiation (ISR)
effects in prompt \jpsi inclusive production at B factories. ISR enhances
cross section \sigma(e^-e^+\to\jpsi+gg+X) by about , which is almost
the same size as the QCD and relativistic correction. Moreover, ISR slightly
changes \sigma(e^-e^+\to\jpsi+c\bar{c}+X). The \jpsi momentum spectrum in
e^-e^+\to\jpsi+gg+X and in e^-e^+\to\jpsi+c\bar{c}+X is softer after the
photon showering from the initial beam radiation. After combining the
QCD,relativistic, and ISR corrections,a more precise theoretical result is
obtained. The new result provides a more stringent constraint of the
color-octet contribution to \sigma(e^-e^+\to\jpsi+X_{\rm{non-}c\bar{c}}).Comment: journal version;16 pages, 9 figures, 4 table
Colored Particle Production in New Physics at NLO QCD and Its Matching to Parton Showers
In this talk, I show the automated Monte Carlo simulations at next-to-leading
order in QCD as well as its matching to parton showers are already feasible
within the framework of \MG5aMC. I briefly overview the recent activities and
take the colored particle production at the LHC as examples. The tools and the
models are ready for using by both phenomenologists and experimentalists.Comment: 12 pages, 3 figures, 2 tables, contribution to proceedings of XXIII
Cracow EPIPHANY Conference, 9-12 January 2017, IFJ PAN, Cracow, Polan
Boosting perturbative QCD stability in quarkonium production
The aim of this paper is to introduce a general way to stabilize the
perturbative QCD computations of heavy quarkonium production in the boosted or
high-momentum transferring region with tree-level generators only. Such an
approach is possible by properly taking into account the power-enhanced
perturbative contributions in a soft and collinear safe manner without
requiring any complete higher-order computations. The complicated NLO results
for inclusive quarkonium hadroproduction can be well reproduced within our
approach based on a tree-level generator {\sc\small HELAC-Onia}. We have
applied it to estimate the last missing leading-twist contribution from the
spin-triplet color-singlet S-wave production at ,
which is a NNLO term in the expansion for the quarkonium
spectrum. We conclude that the missing NNLO contribution will not change the
order of the magnitude of the short-distance coefficient. Such an approach is
also quite appealing as it foresees broad applications in quarkonium-associated
production processes, which are mostly absent of complete higher-order
computations and fragmentation functions.Comment: 40 pages, 26 figures, 3 tables; v2: journal version, fix a few typos
fixed, add two figures, reorganize the figure
Evaluation of health-related outcomes following a self-management program for older people with heart failure
Background. Heart failure (HF) which is a chronic, disabling disorder is mainly found in older people and is one of the leading causes of hospitalisation and readmission around the world. Unfortunately, the mortality and morbidity rates for HF remain high. HF is a complex combination of symptoms which are related to an inadequate perfusion of the body tissues caused by fluid and sodium retention. Hence, enhancing HF patients’ self-efficacy to change their behaviours to perform fluid & sodium control is one of the most important issues for the management of HF. A self-management program has the potential to raise self-efficacy and self-care which is a method to improve health for those with chronic illness and to decrease patients’ health service utilisation and also to enhance these patients’ health status. Aim. The study aims to examine the effectiveness of a self-management program, based on self-efficacy theory, in older people with heart failure in Taiwan. Methods. An experimental design was used to examine the effectiveness of a self-management program on diet and fluid control among HF patients. A total of 93 subjects from two medical centres in Taiwan were randomly assigned to the intervention and control groups. In order to examine the effectiveness of self-management, data were collected at baseline, week 4, and week 12 using the following instruments: self-efficacy for salt and fluid control, HF self-management behaviour, HF related symptoms, and body weight. Moreover, health service utilisation and patient’s evaluation of care received were collected on all patients for the 12 weeks prior to commencing the study and for the 12 week study period. Demographic and disease information was also collected including age, gender, marital state, education, and New York Heart Association (NYHA) functional classification. A structured, individualized self-management training program created by the investigator was implemented for the intervention group through home visits and telephone follow-ups. This program emphasized self-monitoring of diet control and body weight for the self-management of heart failure. The purpose was to improve patients’ self-efficacy in their diet control behaviour. The “diet control” in this study focussed on sodium and fluid restriction. Outcome measures were analysed using the Statistical Package for the Social Sciences (SPSS) 15.0 version, and the level of significance (á) was set at 0.05 for statistical analysis. Results. There were differences for older Taiwanese HF patients’ self-efficacy for salt and fluid control, self-management behaviour, and HF related symptoms for participants who received a self-management intervention compared to those who did not. However, there were no significant differences between the two groups in weight and health serves utilization (p>.001). Conclusion. The self-management program had a positive impact on the improvement of self-efficacy for salt and fluid control, HF related self-management behaviours and symptoms in older Taiwanese with HF. This program may bridge the gap between theory and practice. Health care providers need to provide older people in Taiwan with HF the appropriate skills for self-managing their condition and thereby promoting their health status. These patients with HF and their caregivers have to receive individualized education that emphasizes self-efficacy in the self-management of their disease, thus improving their quality of life
HELAC-Onia: an automatic matrix element generator for heavy quarkonium physics
By the virtues of the Dyson-Schwinger equations, we upgrade the published
code \mtt{HELAC} to be capable to calculate the heavy quarkonium helicity
amplitudes in the framework of NRQCD factorization, which we dub
\mtt{HELAC-Onia}. We rewrote the original \mtt{HELAC} to make the new program
be able to calculate helicity amplitudes of multi P-wave quarkonium states
production at hadron colliders and electron-positron colliders by including new
P-wave off-shell currents. Therefore, besides the high efficiencies in
computation of multi-leg processes within the Standard Model, \mtt{HELAC-Onia}
is also sufficiently numerical stable in dealing with P-wave quarkonia (e.g.
) and P-wave color-octet intermediate states. To the best
of our knowledge, it is a first general-purpose automatic quarkonium matrix
elements generator based on recursion relations on the market.Comment: Published version. 24 pages,1 figure, 7 tables, HELAC-Onia is
available from http://helac-phegas.web.cern.ch/helac-phega
Randomized Row and Column Iterative Methods with a Quantum Computer
We consider the quantum implementations of the two classical iterative
solvers for a system of linear equations, including the Kaczmarz method which
uses a row of coefficient matrix in each iteration step, and the coordinate
descent method which utilizes a column instead. These two methods are widely
applied in big data science due to their very simple iteration schemes. In this
paper we use the block-encoding technique and propose fast quantum
implementations for these two approaches, under the assumption that the quantum
states of each row or each column can be efficiently prepared. The quantum
algorithms achieve exponential speed up at the problem size over the classical
versions, meanwhile their complexity is nearly linear at the number of steps
QCD next-to-leading-order predictions matched to parton showers for vector-like quark models
Vector-like quarks are featured by a wealth of beyond the Standard Model
theories and are consequently an important goal of many LHC searches for new
physics. Those searches, as well as most related phenomenological studies,
however rely on predictions evaluated at the leading-order accuracy in QCD and
consider well-defined simplified benchmark scenarios. Adopting an effective
bottom-up approach, we compute next-to-leading-order predictions for
vector-like-quark pair-production and single production in association with
jets, with a weak or with a Higgs boson in a general new physics setup. We
additionally compute vector-like-quark contributions to the production of a
pair of Standard Model bosons at the same level of accuracy. For all processes
under consideration, we focus both on total cross sections and on differential
distributions, most these calculations being performed for the first time in
our field. As a result, our work paves the way to precise extraction of
experimental limits on vector-like quarks thanks to an accurate control of the
shapes of the relevant observables and emphasize the extra handles that could
be provided by novel vector-like-quark probes never envisaged so farComment: 21 pages, 12 figures, 6 tables; model files available from
http://feynrules.irmp.ucl.ac.be/wiki/NLOModels; version accepted by EPJ
Rare two-body decays of the top quark into a bottom meson plus an up or charm quark
Rare two-body decays of the top quark into a neutral bottom-quark meson plus
an up- or charm-quark: ; ; and , are studied for the first time. The
corresponding partials widths are computed at leading order in the
non-relativistic QCD framework. The sums of all two-body branching ratios
amount to and
,
respectively. The feasibility to observe the decay is estimated in top-pair events produced in proton-proton
collisions at TeV at the LHC and FCC, respectively.
Combining many exclusive hadronic decays, with
or final states, about 50 (16000) events are expected in 3 (20)
ab of integrated luminosity at the LHC (FCC), after typical selection
criteria, acceptance, and efficiency losses. An observation of the two-body
top-quark decay can also be achieved in the interesting dijet final state, where the
decay products are reconstructed as a jet, with 5300 and 1.4 million signal
events above backgrounds expected after selection criteria at the LHC and FCC,
respectively. Such unique final states provide a new direct method to precisely
measure the top-quark mass via simple 2-body invariant mass analyses.Comment: 26 pages, 5 figure
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