2,774 research outputs found
Soft gluon resummation in Higgs boson plus two jet production at the LHC
The soft gluon resummation effect in the Higgs boson plus two-jet production at the LHC is studied by applying the transverse momentum dependent factorization formalism. The large logarithms, introduced by the small total transverse momentum of the Higgs boson plus two-jet final state system, are resummed to all orders in the expansion of the strong interaction coupling with the accuracy of Next-to-Leading Logarithm order. This significantly improves the theoretical prediction. We also compare our result with the prediction of the Monte Carlo event generator Pythia8, and find noticeable difference in the distributions of the total transverse momentum and the azimuthal angle correlations of the final state Higgs boson and two-jet system, when applying similar kinematic cuts used in the LHC data analysis. This difference is large enough to affect the measurement of Higgs boson coupling to the vector boson at the future High luminosity LHC
Resummation of transverse momentum and mass logarithms in DIS heavy quark production.
Differential distributions for heavy quark production depend on the heavy
quark mass and other momentum scales, which can yield additional large
logarithms and inhibit accurate predictions. Logarithms involving the heavy
quark mass can be summed in heavy quark parton distribution functions in the
ACOT factorization scheme. A second class of logarithms involving the
heavy-quark transverse momentum can be summed using an extension of
Collins-Soper-Sterman (CSS) formalism. We perform a systematic summation of
logarithms of both types, thereby obtaining an accurate description of
heavy-quark differential distributions at all energies. Our method essentially
combines the ACOT and CSS approaches. As an example, we present angular
distributions for bottom quarks produced in parity-conserving events at large
momentum transfers Q at the ep collider HERA.Comment: 22 pages, 6 figures; minor change
The XYZ states: Experimental and theoretical status and perspectives
The quark model was formulated in 1964 to classify mesons as bound states
made of a quark-antiquark pair, and baryons as bound states made of three
quarks. For a long time all known mesons and baryons could be classified within
this scheme. Quantum Chromodynamics (QCD), however, in principle also allows
the existence of more complex structures, generically called exotic hadrons or
simply exotics. These include four-quark hadrons (tetraquarks and hadronic
molecules), five-quark hadrons (pentaquarks) and states with active gluonic
degrees of freedom (hybrids), and even states of pure glue (glueballs). Exotic
hadrons have been systematically searched for in numerous experiments for many
years. Remarkably, in the past fifteen years, many new hadrons that do not
exhibit the expected properties of ordinary (not exotic) hadrons have been
discovered in the quarkonium spectrum. These hadrons are collectively known as
states. Some of them, like the charged states, are undoubtedly exotic.
Parallel to the experimental progress, the last decades have also witnessed an
enormous theoretical effort to reach a theoretical understanding of the
states. Theoretical approaches include not only phenomenological extensions of
the quark model to exotics, but also modern non-relativistic effective field
theories and lattice QCD calculations. The present work aims at reviewing the
rapid progress in the field of exotic hadrons over the past few years
both in experiments and theory. It concludes with a summary on future prospects
and challenges
Designing Optimal Perovskite Structure for High Ionic Conduction.
Solid-oxide fuel/electrolyzer cells are limited by a dearth of electrolyte materials with low ohmic loss and an incomplete understanding of the structure-property relationships that would enable the rational design of better materials. Here, using epitaxial thin-film growth, synchrotron radiation, impedance spectroscopy, and density-functional theory, the impact of structural parameters (i.e., unit-cell volume and octahedral rotations) on ionic conductivity is delineated in La0.9 Sr0.1 Ga0.95 Mg0.05 O3- δ . As compared to the zero-strain state, compressive strain reduces the unit-cell volume while maintaining large octahedral rotations, resulting in a strong reduction of ionic conductivity, while tensile strain increases the unit-cell volume while quenching octahedral rotations, resulting in a negligible effect on the ionic conductivity. Calculations reveal that larger unit-cell volumes and octahedral rotations decrease migration barriers and create low-energy migration pathways, respectively. The desired combination of large unit-cell volume and octahedral rotations is normally contraindicated, but through the creation of superlattice structures both expanded unit-cell volume and large octahedral rotations are experimentally realized, which result in an enhancement of the ionic conductivity. All told, the potential to tune ionic conductivity with structure alone by a factor of ≈2.5 at around 600 °C is observed, which sheds new light on the rational design of ion-conducting perovskite electrolytes
The effect of cigarette price increase on the cigarette consumption in Taiwan: evidence from the National Health Interview Surveys on cigarette consumption
BACKGROUND: This study uses cigarette price elasticity to evaluate the effect of a new excise tax increase on cigarette consumption and to investigate responses from various types of smokers. METHODS: Our sample consisted of current smokers between 17 and 69 years old interviewed during an annual face-to-face survey conducted by Taiwan National Health Research Institutes between 2000 to 2003. We used Ordinary Least Squares (OLS) procedure to estimate double logarithmic function of cigarette demand and cigarette price elasticity. RESULTS: In 2002, after Taiwan had enacted the new tax scheme, cigarette price elasticity in Taiwan was found to be -0.5274. The new tax scheme brought about an average annual 13.27 packs/person (10.5%) reduction in cigarette consumption. Using the cigarette price elasticity estimate from -0.309 in 2003, we calculated that if the Health and Welfare Tax were increased by another NT$ 3 per pack and cigarette producers shifted this increase to the consumers, cigarette consumption would be reduced by 2.47 packs/person (2.2%). The value of the estimated cigarette price elasticity is smaller than one, meaning that the tax will not only reduce cigarette consumption but it will also generate additional tax revenues. Male smokers who had no income or who smoked light cigarettes were found to be more responsive to changes in cigarette price. CONCLUSIONS: An additional tax added to the cost of cigarettes would bring about a reduction in cigarette consumption and increased tax revenues. It would also help reduce incidents smoking-related illnesses. The additional tax revenues generated by the tax increase could be used to offset the current financial deficiency of Taiwan's National Health Insurance program and provide better public services
Large aortic aneurysm mimicking a cardiac tumor
<p>Abstract</p> <p>Introduction</p> <p>Extrinsic left atrial compression caused by a displaced, crooked descending thoracic aorta is rare. This anomaly may mimic primary cardiac tumors or metastatic neoplasms from the first look.</p> <p>Case presentation</p> <p>We reported a 78-year-old woman presented to our emergency room with back pain, increased exercise intolerance and intermittent angina. She also had one syncopal event 1 month ago and gastric cancer post gastrectomy history. Subsequent chest plain film showed no mediastinum widening.</p> <p>Two-dimensional echocardiography was performed and revealed a heterogeneous mass as large as 2.3 × 2.4 cm occupying the left atrium (LA). Three-dimensional echocardiography vividly demonstrated that LA was constrained between the aortic valve (AV) and a luminal structure with pulsatile character suggestive of the aorta.</p> <p>Conclusions</p> <p>We successfully demonstrated the detailed structure and location of an anomalous descending aorta on the oblique imaging plane of RT-3DE, which may not be readily available by traditional 2D method.</p
Physics Opportunities of e+e- Linear Colliders
We describe the anticipated experimental program of an e+e- linear collider
in the energy range 500 GeV -- 1.5 TeV. We begin with a description of current
collider designs and the expected experimental environment. We then discuss
precision studies of the W boson and top quark. Finally, we review the range of
models proposed to explain the physics of electroweak symmetry breaking and
show, for each case, the central role that the linear collider experiments will
play in elucidating this physics. (to appear in Annual Reviews of Nuclear and
Particle Science)Comment: 93 pages, latex + 23 figures; typos corrections + 1 reference adde
The synergistic effect of cigarette taxes on the consumption of cigarettes, alcohol and betel nuts
<p>Abstract</p> <p>Background</p> <p>Consumption of cigarettes and alcoholic beverages creates serious health consequences for individuals and overwhelming financial burdens for governments around the world. In Asia, a third stimulant – betel nuts – increases this burden exponentially. For example, individuals who simultaneously smoke, chew betel nuts and drink alcohol are approximately 123 times more likely to develop oral, pharyngeal and laryngeal cancer than are those who do not.</p> <p>To discourage consumption of cigarettes, the government of Taiwan has imposed three taxes over the last two decades. It now wishes to lower consumption of betel nuts. To assist in this effort, our study poses two questions: 1) Will the imposition of an NT10 tax on overall cigarette consumption as well as the cross price elasticities of cigarettes, betel nuts, and alcoholic beverages.</p> <p>Methods</p> <p>To establish the Central Bureau of Statistics demand function, we used cigarette, betel nut, and alcoholic beverage price and sales volume data for the years 1972–2002. To estimate the overall demand price elasticity of cigarettes, betel nuts, and alcoholic beverages, we used a seemingly unrelated regression analysis.</p> <p>Results</p> <p>We find that the NT10 health tax on cigarettes will reduce betel nut consumption by 20.07% and alcohol consumption by 7.5%.</p> <p>Conclusion</p> <p>The assessment of a health tax on cigarettes as a smoking control policy tool yields a win-win outcome for both government and consumers because it not only reduces cigarette consumption, but it also reduces betel nut and alcoholic beverage consumption due to a synergistic relationship. Revenues generated by the tax can be used to fund city and county smoking control programs as well as to meet the health insurance system's current financial shortfall.</p
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