CAS Institute of High Energy Physics

Beijing, China

CAS Institute of High Energy Physics

Beijing, China
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Zhang Y.,CAS Institute of High Energy Physics
International Journal of Modern Physics A | Year: 2016

After the Higgs discovery, it is believed that a circular e+e- collider could serve as a Higgs factory. The high energy physics community in China launched a study of a 50-100 km ring collider. A preliminary conceptual design report (Pre-CDR) has been published in early 2015. This report is based on a 54-km ring design. Some progress on beam-beam effect study after Pre-CDR is shown in the paper. We estimate the beamstrahlung lifetime using a pure strong-strong code as a comparison with the result obtained using a quasi-strong-strong method. The effect of parasitic crossing in the pretzel scheme is also estimated for the very first time. The feasibility of the main parameters for partial double ring scheme are evaluated from the point view of beam-beam interaction. © 2016 World Scientific Publishing Company.


Geng H.,CAS Institute of High Energy Physics
International Journal of Modern Physics A | Year: 2016

CEPC was proposed as an electron and positron collider ring with a circumference of 50-100 km to study the Higgs boson. Since the proposal was made, the lattice design for CEPC has been carried out and a preliminary conceptual design report has been written at the end of 2014. In this paper, we will describe the principles of pretzel scheme design, which is one of most important issues in CEPC lattice design. Then, we will show the modification of the lattice based on the lattice design shown in the Pre-CDR. The latest pretzel orbit design result will also be shown. The issues remained to be solved in the present design will be discussed and a brief summary will be given at the end. © 2016 World Scientific Publishing Company.


Grant
Agency: European Commission | Branch: FP7 | Program: CSA | Phase: INFRA-2012-3.3. | Award Amount: 2.12M | Year: 2012

CHAIN-REDS vision is to promote and support technological and scientific collaboration across different eInfrastructures established and operated in various continents, in order to facilitate their uptake and use by established and emerging Virtual Research Communities (VRCs) but also by single researchers, promoting instruments and practices that can facilitate their inclusion in the community of users. The project aims to support and disseminate the best practices currently adopted in Europe and other continents, and promote and facilitate interoperability among different regional eInfrastructures. CHAIN-REDS gathers the main stakeholders of regional eInfrastructures, collectively engaged in studying and defining a path towards a global eInfrastructure ecosystem that will allow VRCs, research groups and even single researchers to access and efficiently use worldwide distributed resources (i.e. computing, storage, data, services, tools, applications). The core objective of CHAIN-REDS project is to promote, coordinate and support the effort of a critical mass of non-European eInfrastructures for Research and Education to collaborate with Europe addressing interoperability and interoperation of Grids and other Distributed Computing Infrastructures. From this perspective, CHAIN-REDS will optimise the interoperation of European infrastructures with those present in other 6 regions of the world, both from development and use point of view, and catering to different communities.\nOverall, CHAIN-REDs will provide input for future strategies and decision-making regarding collaboration with other regions on eInfrastructure deployment and availability of related data; it will raise the visibility of eInfrastructures towards intercontinental audiences, covering most of the world and will provide support to establish globally connected and interoperable infrastructures, in particular between EU and the developing regions.


Gu J.,CAS Institute of High Energy Physics | Liu Z.,Fermi National Accelerator Laboratory
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2016

A very plausible explanation for the recently observed diphoton excess at the 13 TeV LHC is a (pseudo)scalar with mass around 750 GeV, which couples to a gluon pair and to a photon pair through loops involving vectorlike quarks (VLQs). To accommodate the observed rate, the required Yukawa couplings tend to be large. A large Yukawa coupling would rapidly run up with the scale and quickly reach the perturbativity bound, indicating that new physics, possibly with a strong dynamics origin, is nearby. The case becomes stronger especially if the ATLAS observation of a large width persists. In this paper we study the implication on the scale of new physics from the 750 GeV diphoton excess using the method of renormalization group running with careful treatment of different contributions and perturbativity criterion. Our results suggest that the scale of new physics is generically not much larger than the TeV scale, in particular if the width of the hinted (pseudo)scalar is large. Introducing multiple copies of VLQs, lowering the VLQ masses, and enlarging VLQ electric charges help reduce the required Yukawa couplings and can push the cutoff scale to higher values. Nevertheless, if the width of the 750 GeV resonance turns out to be larger than about 1 GeV, it is very hard to increase the cutoff scale beyond a few TeVs. This is a strong hint that new particles in addition to the 750 GeV resonance and the vectorlike quarks should be around the TeV scale. © 2016 American Physical Society.


Zhang J.,CAS Institute of High Energy Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

We consider a restricted type-I seesaw scenario with four texture zeros in the neutrino Yukawa matrix, in the weak basis where both the charged-lepton Yukawa matrix and the Majorana mass matrix for right-handed neutrinos are diagonal and real. Inspired by grand unified theories, we further require the neutrino Yukawa matrix to exhibit a hierarchical pattern similar to that in the up-type quark Yukawa matrix. With such a hierarchy requirement, we find that leptogenesis, which would operate in an N2-dominated scenario with the asymmetry generated by the next-to-lightest right-handed neutrino N2, can greatly reduce the number of allowed textures and that it disfavors the scenario that three light neutrinos are quasidegenerate. Such a quasidegenerate scenario of light neutrinos may soon be tested in upcoming neutrino experiments. © 2015 American Physical Society.


Xing Z.-Z.,CAS Institute of High Energy Physics
Chinese Physics C | Year: 2012

The Daya Bay collaboration has recently reported its first e e oscillation result which points to θ 13 8.8 ± 0.8 (best-fit ±1σ range) or θ 13 0 at the 5.2σ level. The fact that this smallest neutrino mixing angle is not strongly suppressed motivates us to look into the underlying structure of lepton flavor mixing and CP violation. Two phenomenological strategies are outlined: (1) the lepton flavor mixing matrix U consists of a constant leading term U 0 and a small perturbation term ΔU; and (2) the mixing angles of U are associated with the lepton mass ratios. Some typical patterns of U 0 are reexamined by constraining their respective perturbations with current experimental data. We illustrate a few possible ways to minimally correct U 0 in order to fit the observed values of three mixing angles. We point out that the structure of U may exhibit an approximate μ-τ permutation symmetry in modulus, and reiterate the geometrical description of CP violation in terms of the leptonic unitarity triangles. The salient features of nine distinct parametrizations of U are summarized, and its Wolfenstein-like expansion is presented by taking U 0 to be the democratic mixing pattern. © 2012 Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Sciences and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.


Araki T.,CAS Institute of High Energy Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

We introduce a small correction term, δMν, in the neutrino sector and examine whether a large θ13 and an almost maximal θ23 can simultaneously be obtained starting from the tri-bimaximal neutrino mixing. It is found that one can easily gain θ13 which is favored by the recent T2K experiment, by taking account of the enhancement due to the degeneracy among three neutrino masses. We also find that (δMν)22=(δM ν)33 is a key condition for θ23. © 2011 American Physical Society.


Yuan C.-Z.,CAS Institute of High Energy Physics
International Journal of Modern Physics A | Year: 2014

In this article, we review the recent experimental studies on the charmoniumlike states, mainly from the e+e- annihilation experiments BESIII, Belle, BaBar, and CLEO-c, and the hadron collider experiment LHCb. We discuss the results on the X(3872), the vector Y states [Y(4008), Y(4660), and those in e+e- → π+π -hc], and the charged charmoniumlike Z- c states. © 2014 World Scientific Publishing Company.


Yuan C.-Z.,CAS Institute of High Energy Physics
Chinese Physics C | Year: 2014

The cross sections of e+e -→π+π-hc at center-of-mass energies from 3.90 to 4.42 GeV were measured by the BESIII and the CLEO-c experiments. Resonant structures are evident in the e +e-→π+π-hc line shape. The fit to the line shape results in a narrow structure at a mass of (4216±18) MeV/c2 and a width of (39±32) MeV, and a possible wide structure of mass (4293±9) MeV/c2 and width (222±67) MeV. Here, the errors are combined statistical and systematic errors. This may indicate that the Y(4260) state observed in e+e -→π+π-J/ψ has a fine structure in it. © 2014 Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Sciences and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.


Xing Z.-Z.,CAS Institute of High Energy Physics
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

Recent neutrino oscillation data hint that the smallest neutrino mixing angle θ13 is possible to lie in the range 5°≲θ13≲12° We show that reasonable perturbations to the democratic mixing pattern, which is geometrically related to the tri-bimaximal mixing pattern through an equal shift θ*≃9.7° of two large mixing angles, can naturally produce a nearly tri-bimaximal neutrino mixing matrix V with sufficiently large θ13. Two especially simple but viable scenarios of V are proposed and their phenomenological consequences are discussed. © 2010 Elsevier B.V.

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