998 resultados para ATLAS, particle physics, SM, ZZ, aTGC


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We present precise tests of CP and CPT symmetry based on the full data set of K -> pi pi decays collected by the KTeV experiment at Fermi National Accelerator Laboratory during 1996, 1997, and 1999. This data set contains 16 x 10(6) K -> pi(0)pi(0) and 69 x 10(6) K -> pi(+)pi(-) decays. We measure the direct CP violation parameter Re(epsilon'/epsilon) = (19.2 +/- 2.1) x 10(-4). We find the K(L) -> K(S) mass difference Delta m = (5270 +/- 12) x 10(6) (h) over tilde s(-1) and the K(S) lifetime tau(S) = (89.62 +/- 0.05) x 10(-12) s. We also measure several parameters that test CPT invariance. We find the difference between the phase of the indirect CP violation parameter epsilon and the superweak phase: phi(epsilon) - phi(SW) =(0.40 +/- 0.56)degrees. We measure the difference of the relative phases between the CP violating and CP conserving decay amplitudes for K -> pi(+)pi(-) (phi(+-)) and for K -> pi(0)pi(0) (phi(00)): Delta phi = (0.30 +/- 0.35)degrees. From these phase measurements, we place a limit on the mass difference between K(0) and (K) over bar (0): Delta M < 4.8 x 10(-19) GeV/c(2) at 95% C.L. These results are consistent with those of other experiments, our own earlier measurements, and CPT symmetry.

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We propose a single optical photon source for quantum cryptography based on the acoustoelectric effect. Surface acoustic waves (SAWs) propagating through a quasi-one-dimensional channel have been shown to produce packets of electrons that reside in the SAW minima and travel at the velocity of sound. In our scheme, the electron packets are injected into a p-type region, resulting in photon emission. Since the number of electrons in each packet can be controlled down to a single electron, a stream of single- (or N-) photon states, with a creation time strongly correlated with the driving acoustic field, should be generated.

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Off-resonance RF pre-saturation was used to obtain contrast in MRI images of polymer gel dosimeters irradiated to doses up to 50 Gy. Two different polymer gel dosimeters composed of 2-hydroxyethyl-acryl ate or methacrylic acid monomers mixed with N, N'-methylene-bisacrylamide (BIS), dispersed in an aqueous gelatin matrix were evaluated. Radiation-induced polymerization of the co-monomers generates a fast-relaxing insoluble polymer. Saturation of the polymer using off-resonance Gaussian RF pulses prior to a spin-echo read-out with a short echo time leads to contrast that is dependent on the absorbed dose. This contrast is attributed to magnetization transfer (MT) between free water and the polymer, and direct saturation of water was found to be negligible under the prevailing experimental conditions. The usefulness of MT imaging was assessed by computing the dose resolution obtained with this technique. We found a low value of dose resolution over a wide range of doses could be obtained with a single experiment. This is an advantage over multiple spin echo (MSE) experiments using a single echo spacing where an optimal dose resolution is achieved over only very limited ranges of doses. The results suggest MT imaging protocols may be developed into a useful tool for polymer gel dosimetry.

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We obtain a class of non-diagonal solutions of the reflection equation for the trigonometric A(n-1)((1)) vertex model. The solutions can be expressed in terms of intertwinner matrix and its inverse, which intertwine two trigonometric R-matrices. In addition to a discrete (positive integer) parameter l, 1 less than or equal to l less than or equal to n, the solution contains n + 2 continuous boundary parameters.

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Models of warped extra dimensions with custodial symmetry usually predict the existence of a light Kaluza-Klein fermion arising as a partner of the right-handed top quark, sometimes called light custodians which we will denote (b) over tilde (R). The production of these particles at the LHC can give rise to multi-W events which could be observed in same-sign dilepton channels, but its mass reconstruction is challenging. In this paper we study the possibility of finding a signal for the pair production of this new particle at the LHC focusing on a rarer, but cleaner decay mode of a light custodian into a Z boson and a b-quark. In this mode it would be possible to reconstruct the light custodian mass. In addition to the dominant standard model QCD production processes, we include the contribution of a Kaluza-Klein gluon first mode. We find that (b) over tilde (R) stands out from the background as a peak in the bZ invariant mass. However, when taking into account only the electronic and muonic decay modes of the Z boson and b-tagging efficiencies, the LHC will have access only to the very light range of masses, m((b) over tilde) = O(500) GeV.

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The discovery of neutrino oscillations provides a solid evidence for nonzero neutrino masses and leptonic mixing. The fact that neutrino masses are so tiny constitutes a puzzling problem in particle physics. From the theoretical viewpoint, the smallness of neutrino masses can be elegantly explained through the seesaw mechanism. Another challenging issue for particle physics and cosmology is the explanation of the matter-antimatter asymmetry observed in Nature. Among the viable mechanisms, leptogenesis is a simple and well-motivated framework. In this paper we briefly review these aspects, making emphasis on the possibility of linking neutrino physics to the cosmological bary asymmetry originated from leptogenesis.

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The main properties of strangelets, namely their energy per baryon, radius and electric charge, are studied in the unpaired magnetized strange quark matter (MSQM) and paired magnetized colour flavour locked (MCFL) phases. Temperature effects are taken into account in order to study their stability compared to the Fe-56 isotope and nonmagnetized strangelets within the framework of the MIT bag model. We conclude that the presence of a magnetic field tends to stabilize the strangelets more, even when temperature is considered. It is also shown that MCFL strangelets are more stable than ordinary MSQM strangelets for typical gap values of the order of O(100) MeV. A distinctive feature in the detection of strangelets either in cosmic rays or in heavy-ion collider experiments could be their electric charge. We find that the electric charge is modified in the presence of the magnetic field, leading to higher (lower) charge values for MSQM (MCFL) strangelets, when compared to the nonmagnetized case.

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We consider a simple extension of the Standard Model by adding two Higgs triplets and a complex scalar singlet to its particle content. In this framework, the CP symmetry is spontaneously broken at high energies by the complex vacuum expectation value of the scalar singlet. Such a breaking leads to leptonic CP violation at low energies. The model also exhibits an A(4) X Z(4) flavor symmetry which, after being spontaneously broken at a high-energy scale, yields a tribimaximal pattern in the lepton sector. We consider small perturbations around the tribimaximal vacuum alignment condition in order to generate nonzero values of theta(13), as required by the latest neutrino oscillation data. It is shown that the value of theta(13) recently measured by the Daya Bay Reactor Neutrino Experiment can be accommodated in our framework together with large Dirac-type CP violation. We also address the viability of leptogenesis in our model through the out-of-equilibrium decays of the Higgs triplets. In particular, the CP asymmetries in the triplet decays into two leptons are computed and it is shown that the effective leptogenesis and low-energy CP-violating phases are directly linked.

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ABSTRACT This dissertation focuses on new technology commercialization, innovation and new business development. Industry-based novel technology may achieve commercialization through its transfer to a large research laboratory acting as a lead user and technical partner, and providing the new technology with complementary assets and meaningful initial use in social practice. The research lab benefits from the new technology and innovation through major performance improvements and cost savings. Such mutually beneficial collaboration between the lab and the firm does not require any additional administrative efforts or funds from the lab, yet requires openness to technologies and partner companies that may not be previously known to the lab- Labs achieve the benefits by applying a proactive procurement model that promotes active pre-tender search of new technologies and pre-tender testing and piloting of these technological options. The collaboration works best when based on the development needs of both parties. This means that first of all the lab has significant engineering activity with well-defined technological needs and second, that the firm has advanced prototype technology yet needs further testing, piloting and the initial market and references to achieve the market breakthrough. The empirical evidence of the dissertation is based on a longitudinal multiple-case study with the European Laboratory for Particle Physics. The key theoretical contribution of this study is that large research labs, including basic research, play an important role in product and business development toward the end, rather than front-end, of the innovation process. This also implies that product-orientation and business-orientation can contribute to basic re-search. The study provides practical managerial and policy guidelines on how to initiate and manage mutually beneficial lab-industry collaboration and proactive procurement.

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CERNin tutkimuskeskuksen rakenteilla olevan hadronikiihdyttimen ers tarkoitus on todistaa Higgsin bosonin olemassaolo. Higgsin bosonin lytyminen yhtenistisi nykyisen hiukkasfysiikan teorian ja antaisi selityksen sille kuinka hiukkaset saavat massansa. Kiihdyttimen CMS koeasema on tarkoitettu erityisesti myonien ilmaisuun. Tm ty liittyy CMS koeaseman RPC-ilmaisintyypin linkkijrjestelmn, jonka tarkoituksena on ksitell ilmaisimelta tulevia myonien aiheuttamia signaaleja ja lhett tiedot trkeksi katsotuista trmystapahtumista tallennettavaksi analysointia varten. Tyss on toteutettu linkkijrjestelmn ohjaus- ja linkkikorteille testiymprist, jolla voidaan todeta jrjestelmn eri osien keskininen yhteensopivuus ja toimivuus. Tyn alkuosassa esitelln ilmaisimen linkkijrjestelmn eri osat ja niiden merkitykset. Tyn loppuosassa kydn lpi eri testimenetelmi ja analysoidaan niiden antamia tuloksia.

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La collaboration CLIC (Compact LInear Collider, collisionneur linaire compact) tudie la possibilit de raliser un collisionneur lectron-positon linaire haute nergie (3 TeV dans le centre de masse) et haute luminosit (1034 cm-2s-1), pour la recherche en physique des particules. Le projet CLIC se fonde sur l'utilisation de cavits acclratrices haute frquence (30 GHz). La puissance ncessaire ces cavits est fournie par un faisceau d'lectrons de basse nergie et de haute intensit, appel faisceau de puissance, circulant paralllement l'acclrateur linaire principal (procd appel Acclration Double Faisceau ). Dans ce schma, un des principaux dfis est la ralisation du faisceau de puissance, qui est d'abord gnr dans un complexe acclrateur basse frquence, puis transform pour obtenir une structure temporelle haute frquence ncessaire l'alimentation des cavits acclratrices de l'acclrateur linaire principal. La structure temporelle haute frquence des paquets d'lectrons est obtenue par le procd de multiplication de frquence, dont la manipulation principale consiste faire circuler le faisceau d'lectrons dans un anneau isochrone en utilisant des dflecteurs radio-frquence (dflecteurs RF) pour injecter et combiner les paquets d'lectrons. Cependant, ce type de manipulation n'a jamais t ralis auparavant et la premire phase de la troisime installation de test pour CLIC (CLIC Test Facility 3 ou CTF3) a pour but la dmonstration faible charge du procd de multiplication de frquence par injection RF dans un anneau isochrone. Cette exprience, qui a t ralise avec succs au CERN au cours de l'anne 2002 en utilisant une version modifie du pr-injecteur du grand collisionneur lectron-positon LEP (Large Electron Positron), est le sujet central de ce rapport. L'exprience de combinaison des paquets d'lectrons consiste acclrer cinq impulsions dont les paquets d'lectrons sont espacs de 10 cm, puis les combiner dans un anneau isochrone pour obtenir une seule impulsion dont les paquets d'lectrons sont espacs de 2 cm, multipliant ainsi la frquence des paquets d'lectrons, ainsi que la charge par impulsion, par cinq. Cette combinaison est ralise au moyen de structures RF rsonnantes sur un mode dflecteur, qui crent dans l'anneau une dformation locale et dpendante du temps de l'orbite du faisceau. Ce mcanisme impose plusieurs contraintes de dynamique de faisceau comme l'isochronicit, ainsi que des tolrances spcifiques sur les paquets d'lectrons, qui sont dfinies dans ce rapport. Les tudes pour la conception de la Phase Prliminaire du CTF3 sont dtailles, en particulier le nouveau procd d'injection avec les dflecteurs RF. Les tests de haute puissance raliss sur ces cavits dflectrices avant leur installation dans l'anneau sont galement dcrits. L'activit de mise en fonctionnement de l'exprience est prsente en comparant les mesures faites avec le faisceau aux simulations et calculs thoriques. Finalement, les expriences de multiplication de frquence des paquets d'lectrons sont dcrites et analyses. On montre qu'une trs bonne efficacit de combinaison est possible aprs optimisation des paramtres de l'injection et des dflecteurs RF. En plus de l'exprience acquise sur l'utilisation de ces dflecteurs, des conclusions importantes pour les futures activits CTF3 et CLIC sont tires de cette premire dmonstration de la multiplication de frquence des paquets d'lectrons par injection RF dans un anneau isochrone.&lt;br/&gt;&lt;br/&gt;The Compact LInear Collider (CLIC) collaboration studies the possibility of building a multi-TeV (3 TeV centre-of-mass), high-luminosity (1034 cm-2s-1) electron-positron collider for particle physics. The CLIC scheme is based on high-frequency (30 GHz) linear accelerators powered by a low-energy, high-intensity drive beam running parallel to the main linear accelerators (Two-Beam Acceleration concept). One of the main challenges to realize this scheme is to generate the drive beam in a low-frequency accelerator and to achieve the required high-frequency bunch structure needed for the final acceleration. In order to provide bunch frequency multiplication, the main manipulation consists in sending the beam through an isochronous combiner ring using radio-frequency (RF) deflectors to inject and combine electron bunches. However, such a scheme has never been used before, and the first stage of the CLIC Test Facility 3 (CTF3) project aims at a low-charge demonstration of the bunch frequency multiplication by RF injection into an isochronous ring. This proof-of-principle experiment, which was successfully performed at CERN in 2002 using a modified version of the LEP (Large Electron Positron) pre-injector complex, is the central subject of this report. The bunch combination experiment consists in accelerating in a linear accelerator five pulses in which the electron bunches are spaced by 10 cm, and combining them in an isochronous ring to obtain one pulse in which the electron bunches are spaced by 2 cm, thus achieving a bunch frequency multiplication of a factor five, and increasing the charge per pulse by a factor five. The combination is done by means of RF deflecting cavities that create a time-dependent bump inside the ring, thus allowing the interleaving of the bunches of the five pulses. This process imposes several beam dynamics constraints, such as isochronicity, and specific tolerances on the electron bunches that are defined in this report. The design studies of the CTF3 Preliminary Phase are detailed, with emphasis on the novel injection process using RF deflectors. The high power tests performed on the RF deflectors prior to their installation in the ring are also reported. The commissioning activity is presented by comparing beam measurements to model simulations and theoretical expectations. Eventually, the bunch frequency multiplication experiments are described and analysed. It is shown that the process of bunch frequency multiplication is feasible with a very good efficiency after a careful optimisation of the injection and RF deflector parameters. In addition to the experience acquired in the operation of these RF deflectors, important conclusions for future CTF3 and CLIC activities are drawn from this first demonstration of the bunch frequency multiplication by RF injection into an isochronous ring.&lt;br/&gt;&lt;br/&gt;La collaboration CLIC (Compact LInear Collider, collisionneur linaire compact) tudie la possibilit de raliser un collisionneur lectron-positon linaire haute nergie (3 TeV) pour la recherche en physique des particules. Le projet CLIC se fonde sur l'utilisation de cavits acclratrices haute frquence (30 GHz). La puissance ncessaire ces cavits est fournie par un faisceau d'lectrons de basse nergie et de haut courant, appel faisceau de puissance, circulant paralllement l'acclrateur linaire principal (procd appel Acclration Double Faisceau ). Dans ce schma, un des principaux dfis est la ralisation du faisceau de puissance, qui est d'abord gnr dans un complexe acclrateur basse frquence, puis transform pour obtenir une structure temporelle haute frquence ncessaire l'alimentation des cavits acclratrices de l'acclrateur linaire principal. La structure temporelle haute frquence des paquets d'lectrons est obtenue par le procd de multiplication de frquence, dont la manipulation principale consiste faire circuler le faisceau d'lectrons dans un anneau isochrone en utilisant des dflecteurs radio-frquence (dflecteurs RF) pour injecter et combiner les paquets d'lectrons. Cependant, ce type de manipulation n'a jamais t ralis auparavant et la premire phase de la troisime installation de test pour CLIC (CLIC Test Facility 3 ou CTF3) a pour but la dmonstration faible charge du procd de multiplication de frquence par injection RF dans un anneau isochrone. L'exprience consiste acclrer cinq impulsions, puis les combiner dans un anneau isochrone pour obtenir une seule impulsion dans laquelle la frquence des paquets d'lectrons et le courant sont multiplis par cinq. Cette combinaison est ralise au moyen de structures dflectrices RF qui crent dans l'anneau une dformation locale et dpendante du temps de la trajectoire du faisceau. Les rsultats de cette exprience, qui a t ralise avec succs au CERN au cours de l?anne 2002 en utilisant une version modifie du pr-injecteur du grand collisionneur lectron-positon LEP (Large Electron Positon), sont prsents en dtail.

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The fascinating search of the inner boundaries of the Universe, has been entangled, since the birth of greek philosophy 25 centuries ago, with the main epistemological changes in the History of Science. This paper does not intend to present a systematic description of the discovery of the elementary particles. By stressing the main achievements of the knowledge of matter's structure and their dependence on symmetry arguments, it is argued that even considering profound differences in each historical period, there is a paradgima of atom shared by Chemistry and Particle Physics. This text could help High School Teachers of Chemistry and Physics, as well as motivate them, in the challenge of explaining to their pupils how the idea of atom evolved.

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Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.

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Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.