Benign nocturnal alternating hemiplegia of childhood: a new case with unusual findings

It has been described a neuro developmental disorder labelled “Benign nocturnal alternating hemiplegia of childhood” (BNAHC) characterized by recurrent attacks of nocturnal hemiplegia without progression to neurological or intellectual impairment. We report a female patient who at 11 months revealed a motionless left arm, unusual crying without impairment of consciousness and obvious precipitating factors. The attacks occur during sleep in the early morning with lack of ictal and interictal electroencephalographic abnormalities, progressive neurological deficit, and cognitive impairment. Unlike previous reports of BNAHC our patient come from a family with a history of both migraine, hemiplegic migraine, and sleep disorders. Our study remarks on the typical features described in previous studies and stresses the uncommon aspects that could help to identify the disorder which is likely to have been underestimated. Despite some clinical similarities between BNAHC and familiar hemiplegic migraine and alternating hemiplegia of childhood, the genetic analyses of our patient did not reveal genetic mutations found in both disorders

Investigating Supergiant Fast X-ray Transients with LOFT

Supergiant Fast X-ray Transients (SFXT) are a class of High-Mass X-ray Binaries whose optical counterparts are O or B supergiant stars, and whose X-ray outbursts are ~ 4 orders of magnitude brighter than the quiescent state. LOFT, the Large Observatory For X-ray Timing, with its coded mask Wide Field Monitor (WFM) and its 10 m^2 class collimated X-ray Large Area Detector (LAD), will be able to dramatically deepen the knowledge of this class of sources. It will provide simultaneous high S/N broad-band and time-resolved spectroscopy in several intensity states, and long term monitoring that will yield new determinations of orbital periods, as well as spin periods. We show the results of an extensive set of simulations performed using previous observational results of these sources obtained with Swift and XMM-Newton. The WFM will detect all SFXT flares within its field of view down to a 15-20 mCrab in 5ks. Our simulations describe the outbursts at several intensities (F_(2-10keV)=5.9x10^-9 to 5.5x10^-10 erg cm^-2 s^-1), the intermediate and most common state (10^-11 erg cm^-2 s^-1), and the low state (1.2x10^-12 to 5x10^-13 erg cm^-2 s^-1). We also considered large variations of N_H and the presence of emission lines, as observed by Swift and XMM-Newton.Comment: Proceedings of the 5th International Symposium on High-Energy Gamma-Ray Astronomy (Gamma2012), Heidelberg. 4 pages, 3 figures, 1 tabl

Generalized Gluon Currents and Applications in QCD

We consider the process containing two quark lines and an arbitrary number of gluons in a spinor helicity framework. A current with two off-shell gluons appears in the amplitude. We first study this modified gluon current using recursion relations. The recursion relation for the modified gluon current is solved for the case of like-helicity gluons. We apply the modified gluon current to compute the amplitude for $q \bar q \rightarrow q \bar q gg \cdots g$ in the like-helicity gluon case.Comment: 80 pages, 2 figures (appended in pictex), CLNS 91/112

How accurately can we measure the W cross section?

We study the QCD sources of systematic uncertainties in the experimental extraction of the W cross section at hadron colliders. The uncertainties appear in the evaluation of the detector acceptances used to convert the number of observed events into a total production cross section. We consider the effect of NLO corrections, as well as of the inclusion of parton showers, and evaluate the impact of spin correlations and of PDF and scale uncertainties.Comment: 16 pages, 6 figure

One Loop Multiphoton Helicity Amplitudes

We use the solutions to the recursion relations for double-off-shell fermion currents to compute helicity amplitudes for $n$-photon scattering and electron-positron annihilation to photons in the massless limit of QED. The form of these solutions is simple enough to allow {\it all}\ of the integrations to be performed explicitly. For $n$-photon scattering, we find that unless $n=4$, the amplitudes for the helicity configurations (+++...+) and (-++...+) vanish to one-loop order.Comment: 27 pages + 4 uuencoded figures (included), Fermilab-Pub-93/327-T, RevTe

Multiphoton Production at High Energies in the Standard Model I

We examine multiphoton production in the electroweak sector of the Standard Model in the high energy limit using the equivalence theorem in combination with spinor helicity techniques. We obtain recursion relations for currents consisting of a charged scalar, spinor, or vector line that radiates $n$ photons. Closed form solutions to these recursion relations for arbitrary $n$ are presented for the cases of like-helicity and one unlike-helicity photon production. We apply the currents singly and in pairs to obtain amplitudes for processes involving the production of $n$ photons with up to two unlike helicities from a pair of charged particles. The replacement of one or more photons by transversely polarized $$Z$-bosons is also discussed.Comment: 75 pages, CLNS 91/111

Heavy neutrino signals at large hadron colliders

We study the LHC discovery potential for heavy Majorana neutrino singlets in the process pp -> W+ -> l+ N -> l+ l+ jj (l=e,mu) plus its charge conjugate. With a fast detector simulation we show that backgrounds involving two like-sign charged leptons are not negligible and, moreover, they cannot be eliminated with simple sequential kinematical cuts. Using a likelihood analysis it is shown that, for heavy neutrinos coupling only to the muon, LHC has 5 sigma sensitivity for masses up to 200 GeV in the final state mu+- mu+- jj. This reduction in sensitivity, compared to previous parton-level estimates, is driven by the ~ 10^2-10^3 times larger background. Limits are also provided for e+- e+- jj and e+- mu+- jj final states, as well as for Tevatron. For heavy Dirac neutrinos the prospects are worse because backgrounds involving two opposite charge leptons are much larger. For this case, we study the observability of the lepton flavour violating signal e+- mu-+ jj. As a by-product of our analysis, heavy neutrino production has been implemented within the ALPGEN framework.Comment: Latex 36 pages, 49 PS figures. Major extension incorporating analysis for e+- e+-, e+- mu+- and e+- mu-+ final states. Final version to appear in JHE