92,023 research outputs found
Analysis of J/Psi production with the CMS detector at the Large Hadron Collider
No full textThe J/psi particle is a vector meson with a mass of 3096.916±0.011 MeV. It has been observed in 1974 by two experiments at Stanford and Brookhaven, and is the first bound state of a charm quark and an anticharm quark ever discovered in the history of particle physics.
Differently from lighter quarks, the charm quark is characterized by a rest mass significantly greater than the typical energy scale of Quantum Chromo Dynamics processes, which take place during the binding of the meson. This greater mass results in its constituent quarks being relatively "slow" inside it, justifying a non-relativistic description of its production process. The J/psi, along with other charm-anticharm bound states, represents an important laboratory where the theoretical models of the strong interaction are verified.
Heavy mesons are produced in copious amounts in high energy proton-proton collisions, and the recent beginning of experiments at the CERN Large Hadron Collider has given an opportunity to study the behavior of J/psi production at a center-of-mass energy of 7 TeV with the CMS detector. This detector has been designed as a general-purpose one and is capable of good performance in this kinds of studies, especially in the J/psi to mu+ mu- decay channel.
Indeed, the past 20 years have seen a revival of interest in the study of the production process of the J/psi. A measurement performed by the CDF experiment in 1992-1993 at the Tevatron p-pbar collider found the production cross-section to be larger than the theoretical prediction by a factor of 50. Consequently, the model in use at the time - the Color Singlet Model - had to be abandoned in favor of a Non-Relativistic QCD description called the Color Octet Model.
Recently, also this model has been put into discussion, as the predictions it makes on the polarization of the J/psi seem not to match experimental data by the E866, HERA-B and CDF II experiments, and even more puzzling is the fact that the E866 and HERA-B measurement are inconsistent. A possible explanation of these inconsistencies may be hidden in the different experimental conditions under which these experiments took place (mainly, the detector acceptances), and the fact that the measurements were performed in different frames of reference.
Once identified the importance of the cross-section and polarization measurements, I present the cross-section measurement performed on data taken in 2010 with the CMS detector and present the ongoing effort in measuring the J/psi polarization by the CMS collaboration - in which I have worked as a student for the purpose of this thesis.
In my thesis I introduce a frame-invariant approach which should overcome these elements and provide a clear picture of the behavior of the polarization (longitudinal, transverse or a combination of these states) as a function of transverse momentum.
The measurement requires a series of introductory steps aimed at understanding all aspects of detector response to muons, among them is the calculation of the detector acceptance for the muon pairs with Monte Carlo simulations, the study based on real data of the tracking efficiency, that of muon identification efficiency and that of trigger efficiency, the latter being one of my responsibilities during my work.
The efficiency study has been performed by the use of the "Tag and Probe" method for resonances decaying to dimuons, where a muon of the pair is required to pass a series of very tight cuts. The pairs surviving this extreme skimming have the other muon analyzed, in order to perform a statistical measurement on the relevant variable
Xiao-yan and Dr. Ma Qiwei beside John Ma Statue
No full textA photograph of Xiao-yan and Dr. Ma Qiwei standing beside the statue of John Ma on the campus of Tsinghua University. John Ma was Ma Qiwei's father.To learn more about John Ma, see: https://springfield.as.atlas-sys.com/agents/people/677
To learn more about Ma Qiwei, see: https://springfield.as.atlas-sys.com/agents/people/68
Pulsed electromagnetic fields promote osteoblast mineralization and maturation needing the existence of primary cilia
No full textAbstract not available.Juan-Li Yan, Jian Zhou, Hui-Ping Ma, Xiao-Ni Ma, Yu-Hai Gao,Wen-Gui Shi, Qing-Qing Fang, Qian Ren, Cory J. Xian, Ke-Ming Che
From divergence to convergence : re-evaluating the history behind China's economic boom
No full textChina’s long-term economic dynamics pose a formidable challenge to economic historians. The Qing
Empire (1644-1911), the world’s largest national economy before 1800, experienced a tripling of
population during the 17th and 18th centuries with no signs of diminishing per capita income. While the
timing remains in dispute, a vast gap emerged between newly rich industrial nations and China’s lagging
economy in the wake of the Industrial Revolution. Only with an unprecedented growth spurt beginning
in the late 1970s did this great divergence separating China from the global leaders substantially
diminish, allowing China to regain its former standing among the world’s largest economies. This essay
develops an integrated framework for understanding that entire history, including both the divergence
and the recent convergent trend. We explain how deeply embedded political and economic institutions
that contributed to a long process of extensive growth before 1800 subsequently prevented China from
capturing the benefits associated with the Industrial Revolution. During the 20th century, the gradual
erosion of these historic constraints and of new obstacles erected by socialist planning eventually
opened the door to China’s current boom. Our analysis links China’s recent development to important
elements of its past, while using recent success to provide fresh perspectives on the critical obstacles
undermining earlier modernization efforts, and their eventual removal
From Divergence to Convergence: Re-evaluating the History Behind China's Economic Boom
No full textChina's long-term economic dynamics pose a formidable challenge to economic historians. The Qing Empire (1644-1911), the world's largest national economy prior to the 19th century, experienced a tripling of population during the 17th and 18th centuries with no signs of diminishing per capita income. In some regions, the standard of living may have matched levels recorded in advanced regions of Western Europe. However, with the Industrial Revolution a vast gap emerged between newly rich industrial nations and China's lagging economy. Only with an unprecedented growth spurt beginning in the late 1970s has the gap separating China from the global leaders been substantially diminished, and China regained its former standing among the world's largest economies. This essay develops an integrated framework for understanding this entire history, including both the long period of divergence and the more recent convergent trend. The analysis sets out to explain how deeply embedded political and economic institutions that had contributed to a long process of extensive growth subsequently prevented China from capturing the benefits associated with new technologies and information arising from the Industrial Revolution. During the 20th century, the gradual erosion of these historic constraints and of new obstacles created by socialist planning eventually opened the door to China's current boom. Our analysis links China's recent economic development to important elements of its past, while using the success of the last three decades to provide fresh perspectives on the critical obstacles undermining earlier modernization efforts, and their removal over the last century and a half.
Veigaia cuneata Ma 1996
No full text97. Veigaia cuneata Ma, 1996 Host/Habitat. Decaying litter. Distribution. Jiexiu: Mianshan (Bai & Ma 2013; Bai & Ma 2014).Published as part of Ma, Min, Li, Sheng-Cai & Fan, Qing-Hai, 2015, Mites and ticks (Acari) in Shanxi Province, China: an annotated checklist, pp. 1-39 in Zootaxa 4006 (1) on page 16, DOI: 10.11646/zootaxa.4006.1.1, http://zenodo.org/record/28926
Neparholaspis subarcuatus Ma & Yan 2001
No full text101. Neparholaspis subarcuatus Ma & Yan, 2001 Neparholaspis subarcuatus Ma & Yan, 2001: 28. Neparholaspis subarcuatus.— Marchenko, 2016: 463. Type locality and habitat: China, Wuhan, Hubei Province, humus soil under trees. Type depository: CDC.Published as part of Quintero-Gutiérrez, Edwin Javier & Halliday, Bruce, 2021, Review of the mite family Parholaspididae Evans, 1956 (Acari: Mesostigmata), pp. 401-459 in Zootaxa 5005 (4) on page 428, DOI: 10.11646/zootaxa.5005.4.1, http://zenodo.org/record/514192
An analysis of characterization in the diary of ma yan
No full textThis research aims to observe The Diary of MA YAN uses characterization method through figurative language by Albertine Minderop. This research explains how characterization method through figurative language can characterize the character of Ma Yan and Ma Yan's Parent. Moreover, characterization method can build the theme of the novel itself. By using qualitative method and content analysis technique, the writer would like to reveal the meaning of the text which the researcher is selected. This research finds Ma Yan's character to be a sensitive, joyful and hard worker. It can be seen from her words. Flowers are to describe her joyful and the word of tears to describe her sensitivity. In addition, she also uses the word of sweat and rush to describe her enthusiasm and optimism to face her life and achieve a better life in the future. Furthermore, Ma Yan usually uses the word of sweat and blood to characterize her parents as a hard worker and to describe how very hard her parents worked. The last, theme in the autobiographical novel of The Diary of MA YAN is about hard working and struggle to survive in bitterness and difficulty in life.viii, 58 hlm.; ilus.; 30 cm
Parasitus wangdunqingi Ma 1995
No full text87. Parasitus wangdunqingi Ma, 1995 Host/Habitat. Decaying litter, Triticum aestivum (common wheat). Distribution. Linyi (Bai & Ma 2014).Published as part of Ma, Min, Li, Sheng-Cai & Fan, Qing-Hai, 2015, Mites and ticks (Acari) in Shanxi Province, China: an annotated checklist, pp. 1-39 in Zootaxa 4006 (1) on page 15, DOI: 10.11646/zootaxa.4006.1.1, http://zenodo.org/record/28926
Parholaspis wuhanensis Ma & Yan 2001
No full text112. Parholaspis wuhanensis Ma & Yan, 2001 Parholaspis wuhanensis Ma & Yan, 2001: 27. Parholaspis wuhanensis.— Karg & Schorlemmer, 2009: 60. Type locality and habitat: China, Wuhan, Hubei Province, humus soil under trees. Type depository: CDC.Published as part of Quintero-Gutiérrez, Edwin Javier & Halliday, Bruce, 2021, Review of the mite family Parholaspididae Evans, 1956 (Acari: Mesostigmata), pp. 401-459 in Zootaxa 5005 (4) on page 430, DOI: 10.11646/zootaxa.5005.4.1, http://zenodo.org/record/514192
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