16257249
The fast tracker architecture for the LHC baseline luminosity
A. Annovi,a M. Beretta,a, E. Bossini,b A. Boveia,c E. Brubaker,c F. Canelli,c V. Cavasinni,b F. Crescioli,b H. DeBerg,d M. Dell’Orso,b M. Dunford,c M. Franklin,e P. Giannetti,b A. Kapliy,c Y. K. Kim,c P. Laurelli,a A. McCarn,d C. Melachrinos,c C. Mills,e M. Neubauer,d J. Proudfoot, f , M. Piendibene,b G. Punzi,b F. Sarri,b L. Sartori,bh M. Shochet,c L. Tripiccione,i J. Tuggle,c I. Vivarelli,b G. Volpi∗,b K. Yorita,c J. Zhang. f aINFN Frascati, bUniv. and INFN of Pisa, cUniv. of Chicago, dUniv. of Illinois at Urbana-Champain, eHarvard Univ, f Argonne National Lab, hMarie Curie Fellowship, iUniv. and INFN Ferrara
118715122
Physics from Tristan
The TRISTAN e + e − storage ring has delivered a total of about 60 pb−1 to each of the three general purpose solenoidal detectors: AMY, TOPAZ and VENUS. The center-of-mass energy range, between 50 and 64 GeV, is where interference effects between the virtual photon and Z0 mediators of the annihilation process are largest. Experiments at TRISTAN study the electroweak interactions, QCD, and search for new phenomena. Among the reported results are: measurements of R; the observation of forward-backward charge asymmetries for e+e− → lepton pairs, \(e^ + e^ - \to b\bar b\), and \(e^ + e^ - \to q\bar q\); limits on lepton compositeness; determinations of \(\Lambda _{\overline {MS} }\); measurements of various multihadron event properties; evidence for differences between quark and gluon jets; the demonstration of the running of αs and the existence of the triple-gluon coupling; and searches for a variety of new particles. This report describes a few selected results from the AMY experiment.
121568105
PRECISION ELECTROWEAK PHYSICS
54512122
Bunch length beating in PLS storage ring
During the normal operation period in the Pohang Light Source (PLS) storage ring, the spontaneous bunch length oscillation or beating is generated by the nonlinear effects of the RF noise whose frequency is much lower than the bifurcation frequency. Due to the bunch length beating, we can not supply the uniform intensity beams to users. We have described the observed bunch length beating and its mechanism in the PLS storage ring with a simulation.
93080994
Rotations and gauge transformations
The energy-momentum r e l a t i o n for a n o n r e l a t i v i s t i c p a r t i c l e is E : P?/2m, whi le that for a massless p a r t i c l e is E = P. I t was Einstein who un i f i ed these two re la t i ons through his formula E = [p2 + m211/2 In add i t ion to the fourmomentum, a r e l a t i v i s t i c p a r t i c l e has i t s in te rna l space-time degrees o f freedom. When the p a r t i c l e is slow or at res t , the space-time symmetry manifests i t s e l f through by the spin. On the other hand, i f the p a r t i c l e is massless, i t has the h e l i c i t y and gauge degrees of freedom. ~ e question is whether the in te rna l space-time symmetries for massive and massless pa r t i c l es can be un i f i ed . In order to study th i s problem, we use Wigner's l i t t l e groups. I The l i t t l e group is the maximal subgroup o f the Lorentz group which leaves the four-momentum of the p a r t i c l e i nva r i an t . In order to construct a t ransformation which leaves the four-momentum i n v a r i a n t , l e t us consider a p a r t i c l e moving along the z d i r e c t i o n with v e l c i t y parameter m. We can ro ta te th is p a r t i c l e around the y axis by e. We can then make a boost to come back to the o r i g i n a l momentum, me four-momentum is unchanged under th i s boost preceded by the above-mentioned r o t a t i o n . 2 The matr ix which performs th i s t ransformat ion is
15032284
The language of Einstein spoken by optical instruments
The mathematics of Lorentz transformations, called the Lorentz group, continues to play an important role in optical sciences. It is the basic mathematical language for coherent and squeezed states. It is noted that the six-parameter Lorentz group can be represented by two-by-two matrices. Since the beam transfer matrices in ray optics are largely based on two-by-two matrices or ABCD matrices, the Lorentz group is bound to be the basic language for ray optics, including polarization optics, interferometers, lens optics, multilayer optics, and the Poincaré sphere. Because the group of Lorentz transformations and ray optics are based on the same two-by-two matrix formalism, ray optics can perform mathematical operations that correspond to transformations in special relativity. It is shown, in particular, that one-lens optics provides a mathematical basis for unifying the internal space-time symmetries of massive and massless particles in the Lorentz-covariant world.
14420331
Harmonic Oscillators as Bridges between Theories: Einstein, Dirac, and Feynman
Other than scattering problems where perturbation theory is applicable, there are basically two ways to solve problems in physics. One is to reduce the problem to harmonic oscillators, and the other is to formulate the problem in terms of two-by-two matrices. If two oscillators are coupled, the problem combines both two-by-two matrices and harmonic oscillators. This method then becomes a powerful research tool to cover many different branches of physics. Indeed, the concept and methodology in one branch of physics can be translated into another through the common mathematical formalism. Coupled oscillators provide clear illustrative examples for some of the current issues in physics, including entanglement, decoherence, and Feynman's rest of the universe. In addition, it is noted that the present form of quantum mechanics is largely a physics of harmonic oscillators. Special relativity is the physics of the Lorentz group which can be represented by the group of by two-by-two matrices commonly called $SL(2,c)$. Thus the coupled harmonic oscillators can therefore play the role of combining quantum mechanics with special relativity. Both Paul A. M. Dirac and Richard P. Feynman were fond of harmonic oscillators, while they used different approaches to physical problems. Both were also keenly interested in making quantum mechanics compatible with special relativity. It is shown that the coupled harmonic oscillators can bridge these two different approaches to physics.
118905415
Group Contractions: Inonu, Wigner, and Einstein
Einstein's E = mc2 unifies the momentum-energy relation for massive and massless particles. According to Wigner, the internal space–time symmetries of massive and massless particles are isomorphic to O(3) and E(2) respectively. According to Inonu and Wigner, O(3) can be contracted to E(2) in the large-radius limit. It is noted that the O(3)-like little group for massive particles can be contracted to the E(2)-like little group for massless particles in the limit of large momentum and/or small mass. It is thus shown that transverse rotational degress of freedom for massive particles become contracted to gauge degrees of freedom for massless particles.