Beam-size effect and particle losses at SuperBB factory (Italy)

In the colliders, the macroscopically large impact parameters give a substantial contribution to the standard cross section of the $e^+ e^- \to e^+ e^- \gamma$ process. These impact parameters may be much larger than the transverse sizes of the colliding bunches. It means that the standard cross section of this process has to be substantially modified. In the present paper such a beam-size effect is calculated for bremsstrahlung at Super$B$ factory developed in Italy. We find out that this effect reduces beam losses due to bremsstrahlung by about 40%.Comment: 11 pages, 4 figure

The Third California: The Golden State's New Frontier

Documents the new movement of people and jobs to the interior region of the state, and discusses the broad implications of these changes for California as well as other Western states

Polarization of high-energy electrons traversing a laser beam

When polarized electrons traverse a region where the laser light is focused their polarization varies even if their energy and direction of motion are not changed. This effect is due to interference of the incoming electron wave and an electron wave scattered at zero angle. Equations are obtained which determine the variation of the electron density matrix, and their solutions are given. The change in the electron polarization depends not only on the Compton cross section but on the real part of the forward Compton amplitude as well. It should be taken into account, for example, in simulations of the $e \to \gamma$ conversion for future $\gamma \gamma$ colliders.Comment: 11 pages, LaTeX , 2 postscript figures include

Observation of the beam-size effect at HERA

A precise measurement of the spectrum of the photons from $ep$ bremsstrahlung with the ZEUS luminosity monitor at HERA is reported. The measurement shows a reduced rate compared to the Bethe-Heitler spectrum for photon energies below 5~GeV. This suppression, called the beam-size effect, is explained by the finite transverse size of the beam overlap relative to the typical impact parameter in the process of $ep$ bremsstrahlung at HERA energies.Comment: 12 pages, late

Collisionless energy absorption in the short-pulse intense laser-cluster interaction

In a previous Letter [Phys. Rev. Lett. 96, 123401 (2006)] we have shown by means of three-dimensional particle-in-cell simulations and a simple rigid-sphere model that nonlinear resonance absorption is the dominant collisionless absorption mechanism in the intense, short-pulse laser cluster interaction. In this paper we present a more detailed account of the matter. In particular we show that the absorption efficiency is almost independent of the laser polarization. In the rigid-sphere model, the absorbed energy increases by many orders of magnitude at a certain threshold laser intensity. The particle-in-cell results display maximum fractional absorption around the same intensity. We calculate the threshold intensity and show that it is underestimated by the common over-barrier ionization estimate.Comment: 12 pages, 13 figures, RevTeX

Laser cooling of electron beams for linear colliders

A novel method of electron beam cooling is considered which can be used for linear colliders. The electron beam is cooled during collision with focused powerful laser pulse. With reasonable laser parameters (laser flash energy about 10 J) one can decrease transverse beam emittances by a factor about 10 per one stage. The ultimate transverse emittances are much below those achievable by other methods. Beam depolarization during cooling is about 5--15 % for one stage. This method is especially useful for photon colliders and opens new possibilities for e+e- colliders.Comment: 4 pages, Latex, v2 corresponds to the PRL paper with erratum (in 1998) include

Production of para-- and orthopositronium at relativistic heavy ion colliders

We consider the ortho-- and parapositronium production in the process $AA \to AA+$ Ps where A is a nucleus with the charge number Z. The inclusive cross section and the energy distribution of the relativistic Ps are calculated which are of primary interest from the experimental point of view. The accuracy of the corresponding cross sections is given by omitting terms $\sim (Z\alpha )^2/L^2$ for the para--Ps and $\sim (Z\alpha)^2/L$ for the ortho--Ps production where $L=\ln{\gamma^2} \approx 9$ and 16 for the RHIC and the LHC. Within this accuracy the multiphoton (Coulomb) corrections are taken into account. We show that the RHIC and the LHC will be Ps factories with a productions rate of about $10^5 \div 10^8$ relativistic Ps per day. The fraction of the ortho--Ps is expected to be of the same order as that of the para--Ps for Au--Au and Pb--Pb collisions.Comment: 22 pages, 5 figures, RevTeX, misprint correcte

Russia’s Eurasian past, present and future: rival international societies and Moscow’s place in the post-cold war world

The failure of post-Soviet Russia to integrate into the West became evident with the 2014 Ukraine crisis, leading Moscow to accelerate its declared “pivot to the East”. However, the increased dependence on China carries its own risks, such as the danger of becoming Beijing’s junior partner. For an erstwhile superpower that continues to declare and prize its autonomy in international affairs, this is a particularly unappealing prospect. Thus, it remains to be seen whether a genuinely balanced partnership can exist between both countries. This article uses insights from Adam Watson’s pendulum theory to explore Russia’s post-2014 Eurasian predicament. We argue that the rapid rightward swing of the pendulum in the Euro-Atlantic order following the end of the Cold War has proven indigestible for Moscow. The article then moves to discuss the Sino-Russian relationship in the context of the emerging Eurasian space. It concludes that the growing disillusionment of Russian leaders with the West since the 2000s, along with the normative convergence between Moscow and Beijing, has led to a closer partnership between the two. Yet the partnership is also riddled with a number of insecurities on Moscow’s side that could undermine the long-term prospects for cooperation between Russia and China

Appropriation and subversion: pre-communist literacy, communist party saturation, and post-communist democratic outcomes

Twenty-five years after the collapse of communism in Europe, few scholars disagree that the past continues to shape the democratic trajectories of postcommunist states. Precommunist education has featured prominently in this literature’s bundle of “good” legacies because it ostensibly helped foster resistance to communism. The authors propose a different causal mechanism—appropriation and subversion—that challenges the linearity of the above assumptions by analyzing the effects of precommunist literacy on patterns of Communist Party recruitment in Russia’s regions. Rather than regarding precommunist education as a source of latent resistance to communism, the authors highlight the Leninist regime’s successful appropriation of the more literate strata of the precommunist orders, in the process subverting the past democratic edge of the hitherto comparatively more developed areas. The linear regression analysis of author-assembled statistics from the first Russian imperial census of 1897 supports prior research: precommunist literacy has a strong positive association with postcommunist democratic outcomes. Nevertheless, in pursuing causal mediation analysis, the authors find, in addition, that the above effect is mediated by Communist Party saturation in Russia’s regions. Party functionaries were likely to be drawn from areas that had been comparatively more literate in tsarist times, and party saturation in turn had a dampening effect on the otherwise positive effects of precommunist education on postcommunist democracy

Antifascism, the 1956 Revolution and the politics of communist autobiographies in Hungary 1944-2000

This is a postprint of an article whose final and definitive form has been published in Europe-Asia Studies © 2006 University of Glasgow; Europe-Asia Studies is available online at http://www.informaworld.com.Using oral history, this contribution explores the reshaping of individuals' public and private autobiographies in response to different political environments. In particular, it analyses the testimony of those who were communists in Hungary between 1945 and 1956, examining how their experiences of fascism, party membership, the 1956 Revolution and the collapse of communism led them in each case to refashion their life stories. Moreover, it considers how their biographies played varying functions at different points in their lives: to express identification with communism, to articulate resistance and to communicate ambition before 1956; to protect themselves from the state after 1956; and to rehabilitate themselves morally in a society which stigmatised them after 1989.I didn't use this word 'liberation' (felszabadulás), because in 1956 my life really changed. Everybody's lives went through a great change, but mine especially. … I wasn't disgusted with myself that I had called the arrival of the Red Army in 1945 a liberation, but [after 1956] I didn't use it anymore