Prompt Photon and Inclusive π0\pi^0 Production at RHIC and LHC

We present results for prompt photon and inclusive $\pi^0$ production in p-p and A-A collisions at RHIC and LHC energies. We include the full next-to-leading order radiative corrections and nuclear effects, such as nuclear shadowing and parton energy loss. We find the next-to-leading order corrections to be large and $p_T$ dependent. We show how measurements of $\pi^0$ production at RHIC and LHC, at large $p_T$, can provide valuable information about the nature of parton energy loss. We calculate the ratio of prompt photons to neutral pions and show that at RHIC energies this ratio increases with $p_T$ approaching one at $p_T \sim 10$ GeV, due to the large suppression of $\pi^0$ production. We show that at the LHC, this ratio has steep $p_T$ dependence and approaches 10% effect at $p_T \sim 20$ GeV.Comment: Talk presented by I. Sarcevic, to appear in the Proceedings of Quark Matter 2002; 4 pages including 4 color figure

Bifurcation and dynamic response analysis of rotating blade excited by upstream vortices

Acknowledgements The authors acknowledge the projects supported by the National Basic Research Program of China (973 Project)(No. 2015CB057405) and the National Natural Science Foundation of China (No. 11372082) and the State Scholarship Fund of CSC. DW thanks for the hospitality of the University of Aberdeen.Peer reviewedPostprin

The Origin of Large-p_T pi^0 Suppression at RHIC

We present results for inclusive $\pi^0$ production in proton-proton and in Au-Au at RHIC energy $\sqrt s=200$ GeV. We use next-to-leading order perturbative QCD calculation and we include nuclear effects such as parton energy loss and nuclear shadowing. We consider the ratio of $\pi^0$ distribution in Au-Au and p-p collisions for $p_T > 3$ GeV for three cases of parton energy loss: 1) constant parton energy loss per parton scattering, $\epsilon^a_n=const$, 2) Landau-Pomeranchuk-Migdal energy-dependent energy loss, $\epsilon^a_n \sim \sqrt E^a_n$ and 3) Bethe-Heitler energy-dependent energy loss, $\epsilon^a_n \sim E^a_n$. We show that recently observed suppression of $\pi^0$ production in Au-Au collisions at RHIC, which is found to increase with $p_T$ increasing from 3GeV to 8GeV, can be reproduced by $\epsilon^a_n=0.06 E^a_n$. We show that the ratio of prompt photons to neutral pions produced in Au-Au collisions at RHIC has a strong $p_T$ dependence approaching one at $p_T\sim 10$GeV.Comment: minor corrections; version accepted for publication in Physics Letters

Baryon Stopping in Proton-Nucleus Collisions

We calculate the inclusive small-x valence quark production cross section in proton-nucleus collisions at high energies. The calculation is performed in the framework of the Color Glass Condensate formalism. We consider both the case when the valence quark originates inside the nucleus and the case when it originates inside the proton. We first calculate the cross section in the quasi-classical approximation resumming the multiple rescatterings with the nucleus. Then we include the the effects of double logarithmic reggeon evolution and leading logarithmic gluon evolution in the obtained cross section. The calculated nuclear modification factor for the stopped baryons exhibits Cronin enhancement in the quasi-classical approximation and suppression at high energies/rapidities when quantum evolution corrections are included, providing a new observable which can be used to test Color Glass physics.Comment: 30 pages, 12 figures One figure and comments added. Version to appear in Nucl. Phys.

Electromagnetic Signatures of the Color Glass Condensate: Dileptons

We evaluate the invariant cross section for production of dileptons in forward rapidities at RHIC and LHC, using the Color Glass Condensate formalism and present results for the nuclear modification factor $R_{d(p)A}$ as a function of dilepton invariant mass for the most central deuteron (proton)-nucleus collisions.Comment: 11 pages, 5 figure

Classical Initial Conditions for Ultrarelativistic Heavy Ion Collisions

We construct an analytical expression for the distribution of gluons in the state immediately following a heavy ion collision in the quasi-classical limit of QCD given by McLerran-Venugopalan model. The resulting gluon number distribution function includes the effects of all multiple rescatterings of gluons with the nucleons of both colliding nuclei. The typical transverse momentum k of the produced gluons is shown to be of the order of the saturation scale of the nuclei Qs, as predicted by Mueller. We analyze the properties of the obtained distribution and demonstrate that due to multiple rescatterings it remains finite (up to logarithms of k) in the soft transverse momentum limit of k << Qs unlike the usual perturbative initial conditions given by collinear factorization. We calculate the total number of produced gluons and show that it is proportional to the total number of gluons inside the nuclear wave function before the collision with the proportionality coefficient c = 2 ln2.Comment: REVTeX, 19 pages, 11 figure

Exploring the Motivational Journey of Japanese Self-access Center Assistants in Learning English as a Second Language

外国語学習のコンテクストにおいては、自律学習支援室（SACs）は学習者の自律性と関連付けられるのが一般的である (McMurry, Tanner, & Anderson, 2010)。自律的な語学学習者は、正式な授業での学習を補完するために、多様な資料や教材を提供する SACs を頻繁に利用するなど、授業外での学習を行う (Hsieh, 2010)。本定性的研究では、日本の関西地区の私立大学の 8人の日本人 SAC アシスタントに対して、英語の生涯学習の過程、補助教材、および英語学習の動機付けに関する質問調査を実施した。本研究の目的は、調査で取り上げた日本人 SAC アシスタントたちが、 SAC を訪れる他の日本人学生たちにとって好ましいロールモデルとなりえるような自律した学習者にどのようにしてなることが できたのかを検証することである。日本人 SAC アシスタントの回答によると、彼らの英語学習の過程は、小学校時代に楽しみながら学習することから始まり、中学校や高校では今後の進路を大きく左右する試験に合格するために学習し、そして自らの楽しみや、日本人学生あるいは他の国の学生とのコミュニケーション、海外への居住・留学のために学習する自律学習へと発展していった。日本人 SAC アシスタントが SAC を利用する日本人学生と一緒に親密かつ頻繁に学習に取り組む中で、彼らは自分たちが、他の日本人学生が個々の目的のために自分の力で英語 を学べる自律した学習者になっていくための動機づけをする重要な役割を担いうることを認識していった。Self-access centers (SACs) in the context of foreign language learning are commonly associated with learner autonomy (McMurry, Tanner, & Anderson, 2010). Autonomous language learners often complement formal classroom learning with informal learning that may include frequent visits to SACs that offer a wide variety of learning resources and materials (Hsieh, 2010). In this qualitative study, eight Japanese SAC assistants at a private university in the Kansai region of Japan were asked about their lifelong English learning process, resources for learning English, and their motivation for learning English. The purpose of the study was to identify how the Japanese SAC assistants were able to become autonomous language learners who could be positive role models for their Japanese peers who visited the SAC. The assistants reported that their journey of studying English evolved from learning for pleasure when they were in elementary school, studying to pass high-stakes exams in junior high and high school, and finally towards autonomous learning for pleasure, communication with Japanese students and students from other countries, and study abroad. As the Japanese SAC assistants worked closely and frequently with Japanese students who visited the SAC, they realized that they could play a vital role in motivating other Japanese students to become autonomous language learners who could pave their own paths towards studying English for various purposes

Nuclear Modification Factor in d+Au Collisions: Onset of Suppression in the Color Glass Condensate

We perform a quantitative analysis of the nuclear modification factor in deuteron--gold collisions R(dAu) within the Color Glass Condensate approach, and compare our results with the recent data from RHIC experiments. Our model leads to Cronin enhancement at mid-rapidity, while at forward rapidities it predicts strong suppression of R(dAu) at all pT due to low-x evolution. We demonstrate that our results are consistent with the data for dAu charged hadron spectra, R(dAu) and R(CP) recently reported for rapidities in the interval eta=0--3.2 by the BRAHMS experiment at RHIC. We also make a prediction for R(pA) at mid-rapidity in pA collisions at the LHC.Comment: 8 pages, 4 figures; results for negatively charged hadrons at forward rapidities are adde

Quantifying the decay of quantum properties in single-mode states

The dissipative dynamics of Gaussian squeezed states (GSS) and coherent superposition states (CSS) are analytically obtained and compared. Time scales for sustaining different quantum properties such as squeezing, negativity of the Wigner function or photon number distribution are calculated. Some of these characteristic times also depend on initial conditions. For example, in the particular case of squeezing, we find that while the squeezing of CSS is only visible for small enough values of the field intensity, in GSS it is independent of this quantity, which may be experimentally advantageous. The asymptotic dynamics however is quite similar as revealed by the time evolution of the fidelity between states of the two classes.Comment: Accepted versio