DSpace Collection:

Pseudoscalar decay constants of kaon and D-mesons from N-f=2 twisted mass Lattice QCD

2009-06-30T22:00:00Z

Pseudoscalar decay constants of kaon and D-mesons from N-f=2 twisted mass Lattice QCD Blossier, Benoît; Dimopoulos, Pedro; Frezzotti, Roberto; Haas, Benjamin; Herdoiza, Gregorio; Jansen, Karl; Lubicz, Vittorio; Mescia, Federico; Palao, David; Shindler, Andrea; Simula, Silvano; Tarantino, Cecilia; Urbach, Carsten; Wenger, Urs 2009-07 Journal of high energy physics 2009 043 We present the results of a lattice QCD calculation of the pseudoscalar meson decay constants f(pi), f(K), f(D) and f(Ds), performed with N-f =2 dynamical fermions. The simulation is carried out with the tree-level improved Symanzik gauge action and with the twisted mass fermionic action at maximal twist. We have considered for the final analysis three values of the lattice spacing, a similar or equal to 0.10 fm, 0.09 fm and 0.07 fm, with pion masses down to m(pi) similar or equal to 270 MeV. Our results for the light meson decay constants are f(K) =158.1(2.4) MeV and f(K)/f(pi) = 1.210(18). From the latter ratio, by using the experimental determination of Gamma(K -> munu(mu)(gamma))/Gamma(pi -> mu nu(mu)(gamma)) and the average value of vertical bar V-ud vertical bar from nuclear beta decays, we obtain vertical bar V-us vertical bar = 0.2222(34), in good agreement with the determination from semileptonic K-13 decays and the unitarity constraint. For the D and D-s meson decay constants we obtain f(D) =197(9) MeV, f(Ds) = 244(8) MeV and f(Ds)/f(D) = 1.24(3). Our result for f(D) is in good agreement with the CLEO experimental measurement. For f(Ds) our determination is smaller than the PDG 2008 experimental average but in agreement with a recent improved measurement by CLEO at the 1.4 sigma level.

A relativistically smeared spectrum in the neutron star X-ray binary 4U1705-44: looking at the inner accretion disc with X-ray spectroscopy

2009-09-30T22:00:00Z

A relativistically smeared spectrum in the neutron star X-ray binary 4U1705-44: looking at the inner accretion disc with X-ray spectroscopy Di Salvo, T.; D'Ai, A.; Iaria, R.; Burderi, L.; Dovciak, M.; Karas, V.; Matt, Giorgio; Papitto, A.; Piraino, S.; Riggio, A.; Robba, N. R.; Santangelo, A. 2009-10 Monthly Notices of the Royal Astronomical Society 398 2022-2027 Iron emission lines at 6.4-6.97 keV, identified with fluorescent Kalpha transitions, are among the strongest discrete features in the X-ray band. These are therefore one of the most powerful probes to infer the properties of the plasma in the innermost part of the accretion disc around a compact object. In this paper, we present a recent XMM-Newton observation of the X-ray burster 4U 1705-44, where we clearly detect a relativistically smeared iron line at about 6.7 keV, testifying with high statistical significance that the line profile is distorted by high-velocity motion in the accretion disc. As expected from disc reflection models, we also find a significant absorption edgeat about 8.3 keV; this feature appears to be smeared, and is compatible with being produced in the same region where the iron line is produced. From the line profile, we derive the physical parameters of the inner accretion disc with large precision. The line is identified with the Kalpha transition of highly ionized iron, Fe xxv, the inner disc radiusis R-in = 14 +/- 2 R-g (where R-g is the Gravitational radius, GM/c2), the emissivity dependence from the disc radius is r-2.27 +/- 0.08, theinclination angle with respect to the line of sight is i = 39 degrees+/- 1 degrees. Finally, the XMM-Newton spectrum shows evidences of other low-energy emission lines, which again appear broad and their profiles are compatible with being produced in the same region where the iron line is produced.

First lattice QCD Study of the Σ- --> n axial and vector form factors with SU(3) breaking corrections

2006-12-31T23:00:00Z

First lattice QCD Study of the Σ- --> n axial and vector form factors with SU(3) breaking corrections Guadagnoli, Diego; Lubicz, Vittorio; Papinutto, Mauro; Simula, Silvano 2007 Nuclear Physics B 761 63-91 We present the first quenched lattice QCD study of the form factors relevant for the hyperon semileptonic decay Σ−→nℓν. The momentum dependence of both axial and vector form factors is investigated and the values of all the form factors at zero-momentum transfer are presented. Following the same strategy already applied to the decay K0→π−ℓν, the SU(3)-breaking corrections to the vector form factor at zero-momentum transfer, f1(0), are determined with great statistical accuracy in the regime of the simulated quark masses, which correspond to pion masses above ≈0.7 GeV. Besides f1(0) also the axial to vector ratio g1(0)/f1(0), which is relevant for the extraction of the CKM matrix element Vus, is determined with significant accuracy. Due to the heavy masses involved, a polynomial extrapolation, which does not include the effects of meson loops, is performed down to the physical quark masses, obtaining f1(0)=−0.948±0.029 and g1(0)/f1(0)=−0.287±0.052, where the uncertainties do not include the quenching effect. Adding a recent next-to-leading order determination of chiral loops, calculated within the Heavy Baryon Chiral Perturbation Theory in the approximation of neglecting the decuplet contribution, we obtain f1(0) = −0.988 ± 0.029(lattice) ± 0.040(HBChPT). Our findings indicate that SU(3)-breaking corrections are moderate on both f1(0) and g1(0). They also favor the experimental scenario in which the weak electricity form factor, g2(0), is large and positive, and correspondingly the value of |g1(0)/f1(0)| is reduced with respect to the one obtained with the conventional assumption g2(q2)=0 based on exact SU(3) symmetry.

Atomic-scale patterning of hydrogen terminated Ge(001) by scanningtunneling microscopy

2009-11-30T23:00:00Z

Atomic-scale patterning of hydrogen terminated Ge(001) by scanningtunneling microscopy Scappucci, Giordano; Capellini, Giovanni; Lee, W. C. T.; Simmons, M. Y. 2009-12 Nanotechnology 20 495302 In this paper we demonstrate atomic-scale lithography on hydrogenterminated Ge(001). The lithographic patterns were obtained byselectively desorbing hydrogen atoms from a H resist layer adsorbed ona clean, atomically flat Ge(001) surface with a scanning tunnelingmicroscope tip operating in ultra-high vacuum. The influence of thetip-to-sample bias on the lithographic process have been investigated.Lithographic patterns with feature-sizes from 200 to 1.8 nm have beenachieved by varying the tip-to-sample bias. These results open up thepossibility of a scanning-probe lithography approach to the fabricationof future atomic-scale devices in germanium.

Influence of encapsulation temperature on Ge:P delta-doped layers

2009-11-30T23:00:00Z

Influence of encapsulation temperature on Ge:P delta-doped layers Scappucci, Giordano; Capellini, Giovanni; Simmons, M. Y. 2009-12 Physical Review B 80 233202-1 - 233202-4 We present a systematic study of the influence of the encapsulationtemperature on dopant confinement and electrical properties of Ge:Pdelta-doped layers. For increasing growth temperature we observe anenhancement of the electrical properties accompanied by an increasedsegregation of the phosphorous donors, resulting in a slight broadeningof the delta layer. We demonstrate that a step-flow growth achieved atsimilar to 530 degrees C provides the best compromise between highcrystal quality and minimal dopant redistribution, with an electronmobility similar to 128 cm(2)/Vs at a carrier density 1.3x10(14)cm(-2), and a 4.2 K phase coherence length of similar to 180 nm.

Ultradense phosphorus in germanium delta-doped layers

2009-03-31T22:00:00Z

Ultradense phosphorus in germanium delta-doped layers Scappucci, Giordano; Capellini, Giovanni; Lee, W. C. T.; Simmons, M. Y. 2009-04 Applied Physics Letters 94 162106 Phosphorus (P) in germanium (Ge) delta-doped layers are fabricated inultrahigh vacuum by adsorption of phosphine molecules onto anatomically flat clean Ge(001) surface followed by thermal incorporationof P into the lattice and epitaxial Ge overgrowth by molecular beamepitaxy. Structural and electrical characterizations show that P atomsare confined, with minimal diffusion, into an ultranarrow 2-nm-widelayer with an electrically active sheet carrier concentration of4x10(13) cm(-2) at 4.2 K. These results open up the possibility ofultranarrow source/drain regions with unprecedented carrier densitiesfor Ge n-channel field effect transistors.

Nature of "Disorder'' in the Ordered Double Perovskite Sr2FeMoO6

2008-12-31T23:00:00Z

Nature of "Disorder'' in the Ordered Double Perovskite Sr2FeMoO6 Meneghini, Carlo; Ray, Sugata; Liscio, Fabiola; Bardelli, Fabrizio; Mobilio, Settimio; Sarma, D. D. 2009 Physical Review Letters 103 046403 The degree of B/B' alternate cation order is known to heavily influencethe magnetic properties of A(2)BB'O-6 double perovskites although thenature of such disorder has never been critically studied. Our detailedx-ray absorption fine structure studies in conjunction with synchrotronradiation x-ray diffraction experiments on polycrystalline Sr2FeMoO6samples with various degrees of disorder reveal that a very high degreeof short range order is preserved even in samples with highly reducedlong range chemical order. Based on these experimental results and withthe help of detailed structural simulations, we are able to model thenature of the disorder in this important class of materials and discussthe consequent implications on its physical properties.

Buckling of high natural slopes: The case of Lavini di Marco (Trento-Italy)

2009-02-14T23:00:00Z

Buckling of high natural slopes: The case of Lavini di Marco (Trento-Italy) Tommasi, Paolo; Verrucci, Luca; Campedel, Paolo; Veronese, Luigi; Pettinelli, Elena; Ribacchi, Renato 2009-02-15 Engineering Geology 109 93–108 Layered limestones with marly–clayey interbeds are widespread in mountain regions. Where tectonics has not changed the original structure they frequently form homocline slopes, that since the last deglaciation have evolved through planar block slides along bedding joints. A typical dip slope showing this evolution is represented by the left flank of the Adige River valley south of Rovereto (North-Eastern Italy). Even though layers never daylight at the slope toe, the exceptional persistence and weakness of bedding joints allows buckling of layers, which occasionally collapse causing rock avalanches. Before monitoring started, deformations were believed to be no longer active, this conviction being strengthened by the high safety factors provided by limit equilibrium analyses. SAR satellite interferometry performed between 1990 and 2002 and probe inclinometer measures indicate that the slabs located uphill from the buckle folds are slowly sliding. Since some doubts have been raised about rock mass behaviour, slope geometry and hydraulic conditions assumed in the analyses, buckling was back-analysed using the Distinct Element Method (DEM) and the Discontinuous Deformation Analysis (DDA). These treat the rock mass as a discontinuum and account for deformation and failure of the rock material. To perform numerical analyses, rock mass structure, strength and stiffness were determined through extensive in situ and laboratory investigations. For this purpose field surveys, borehole core logging and geophysical surveys were performed and laboratory geotechnical tests on the rock material, clayey interbeds and bedding joints were conducted. Discontinuous analyses confirmed that buckling deformations are definitely possible if some conditions are present (high water pressure, minor flexures). Modelling also indicate that buckling deformations may evolve into failures and should therefore be taken into account in evaluating long term stability of the slope.

Pseudoscalar decay constants of kaon and D-mesons from Nf=2 twisted mass Lattice QCD

2009-06-30T22:00:00Z

Pseudoscalar decay constants of kaon and D-mesons from Nf=2 twisted mass Lattice QCD ETM, Collaboration; Blossier, Benoit; Dimopoulos, Petros; Frezzotti, Roberto; Haas, Benjamin; Herdoiza, Gregorio; Jansen, Karl; Lubicz, Vittorio; Mescia, Federico; Palao, David; Shindler, Andrea; Simula, Silvano; Tarantino, Cecilia; Urbach, Carsten 2009-07 Journal of High Energy Physics 07 043 We present the results of a lattice QCD calculation of the pseudoscalar meson decay constants fπ, fK, fD and fDs, performed with Nf=2 dynamical fermions. The simulation is carried out with the tree-level improved Symanzik gauge action and with the twisted mass fermionic action at maximal twist. We have considered for the final analysis three values of the lattice spacing, a = 0.10 fm, 0.09 fm and 0.07 fm, with pion masses down to mπ = 270 MeV. Our results for the light meson decay constants are fK = 158.1(2.4) MeV and fK/fπ = 1.210(18). From the latter ratio, by using the experimental determination of Γ(K → μbar nuμ(γ))/Γ(π → μbar nuμ(γ)) and the average value of |Vud| from nuclear beta decays, we obtain |Vus| = 0.2222(34), in good agreement with the determination from semileptonic Kl3 decays and the unitarity constraint. For the D and Ds meson decay constants we obtain fD = 197(9) MeV, fDs = 244(8) MeV and fDs/fD = 1.24(3). Our result for fD is in good agreement with the CLEO experimental measurement. For fDs our determination is smaller than the PDG 2008 experimental average but in agreement with a recent improved measurement by CLEO at the 1.4 σ level.

Study of the a0(980) meson via the radiative decay phi -> eta pi0 gamma with the KLOE detector

2009-08-31T22:00:00Z

Study of the a0(980) meson via the radiative decay phi -> eta pi0 gamma with the KLOE detector Ambrosino, Fabio; Bacci, Cesare; Bocchetta, Simona Serena; Ceradini, Filippo; Di Micco, Biagio; Nguyen, Federico 2009-09 Physics Letters B 681 5-13 We have studied the phi-> a0(980) gamma process with the KLOE detector at the Frascati phi-factory DAFNE by detecting the phi -> eta pi0 gamma decays in the final states with η -> gamma gamma and eta -> pi+ pi- pi0. We have measured the branching ratios for both final states: Br(phi -> eta pi0 gamma) = (7.01 ± 0.10 ± 0.20)×10−5 and (7.12 ± 0.13 ± 0.22)×10−5, respectively. We have also extracted the a0(980) mass and its couplings to eta-pi0, K+K−, and to the φ-meson from the fit of the eta-pi0 invariant mass distributions using different phenomenological models.

Search for the K-S -> e(+)e(-) decay with the KLOE detector

2008-12-31T23:00:00Z

Search for the K-S -> e(+)e(-) decay with the KLOE detector Ambrosino, F.; Antonelli, A.; Antonelli, M.; Archilli, F.; Beltrame, R.; Bencivenni, G.; Bertolucci, S.; Bini, C.; Bloise, C.; Bocchetta, Simona Serena; Bossi, F.; Branchini, P.; Campana, P.; Capon, G.; Capriotti, D.; Capussela, T.; Ceradini, Filippo; Ciambrone, P.; Crucianelli, F.; De Lucia, E.; De Santis, A.; De Simone, P.; De Zorzi, G.; Denig, A.; Di Domenico, A.; Di Donato, C.; Di Micco, Biagio; Dreucci, M.; Felici, G.; Ferrer, M. L.; Fiore, S.; Franzini, P.; Gatti, C.; Gauzzi, P.; Giovannella, S.; Graziani, E.; Kluge, W.; Kulikov, V.; Lanfranchi, G.; Lee-Franzini, J.; Leone, D.; Martini, M.; Massarotti, P.; Meola, S.; Miscetti, S.; Moulson, M.; Mueller, S.; Murtas, F.; Napolitano, M.; Nguyen, Federico; Palutan, M.; Pasqualucci, E.; Passeri, A.; Patera, V.; Perfetto, F.; Santangelo, P.; Sciascia, B.; Sciubba, A.; Sibidanov, A.; Spadaro, T.; Testa, M.; Tortora, L.; Valente, P.; Venanzoni, G.; Versaci, R. 2009 Physics Letters B 672 203-208 We present the result of a direct search for the decay K-S -> e(+)e(-),obtained with a sample of e(+)e(-) -> phi -> KSKL events produced at DAphi NE, the Frascati phi-factory, for an integrated luminosity of 1.9fb(-1). The search has been performed using a pure K-S beam tagged bythe simultaneous detection of a K-L interaction in the calorimeter.Background rejection has been optimized by using both kinematic andparticle identification cuts. We find BR(KS -> e(+)e(-)) < 9 x 10(-9)at 90% CL, which improves by an order of magnitude on the previous bestlimit, (C) 2009 Elsevier B.V, All rights reserved.

Precise measurement of Gamma(K -> e nu(gamma))/Gamma(K -> mu nu(gamma))and study of K -> e nu gamma

2009-11-30T23:00:00Z

Precise measurement of Gamma(K -> e nu(gamma))/Gamma(K -> mu nu(gamma))and study of K -> e nu gamma Ambrosino, F.; Antonelli, A.; Antonelli, M.; Archilli, F.; Beltrame, P.; Bencivenni, G.; Bini, C.; Bloise, C.; Bocchetta, Serena; Bossi, F.; Branchini, P.; Capon, G.; Capriotti, D.; Capussela, T.; Ceradini, Filippo; Ciambrone, P.; De Lucia, E.; De Santis, A.; De Simone, P.; De Zorzi, G.; Denig, A.; Di Domenico, A.; Di Donato, C.; Di Micco, Biagio; Dreucci, M.; Felici, G.; Fiore, S.; Franzini, P.; Gatti, C.; Gauzzi, P.; Giovannella, S.; Graziani, E.; Jacewicz, M.; Kulikov, V.; Lanfranchi, G.; Lee-Franzini, J.; Martini, M.; Massarotti, P.; Meola, S.; Miscetti, S.; Moulson, M.; Mueller, S.; Murtas, F.; Napolitano, M.; Nguyen, Federico; Palutan, M.; Passeri, A.; Patera, V.; Santangelo, P.; Sciascia, B.; Sibidanov, A.; Spadaro, T.; Tortora, L.; Valente, P.; Venanzoni, G.; Versaci, R. 2009-12 European Physical Journal C 64 627-636 We present a precise measurement of the ratio R-K = Gamma(K -> enu(gamma))/Gamma(K -> mu nu(gamma)) and a study of the radiativeprocess K -> e nu gamma, performed with the KLOE detector. The resultsare based on data collected at the Frascati e(+)e(-) collider DA Phi NEfor an integrated luminosity of 2.2 fb(-1). We find R-K = (2.493 +/-0.025(stat) +/- 0.019(syst)) x 10(-5), in agreement with the StandardModel expectation. This result is used to improve constraints onparameters of the Minimal Supersymmetric Standard Model with leptonflavor violation. We also measured the differential decay rate dGamma(K -> e nu gamma)/dE(gamma) for photon energies 10 < E-gamma < 250MeV. Results are compared with predictions from theory.

A strong excess in the 20-100 kev emission of ngc 1365

2009-10-31T23:00:00Z

A strong excess in the 20-100 kev emission of ngc 1365 Risaliti, G.; Braito, V.; Laparola, V.; Bianchi, Stefano; Elvis, M.; Fabbiano, G.; Maiolino, R.; Matt, Giorgio; Reeves, J.; Salvati, M.; Wang, J. 2009-11 Astrophysical Journal Letters 705 L1–L5 We present a new Suzaku observation of the obscured active galacticnucleus in NGC 1365, revealing an unexpected excess of X-rays above 20keV of at least a factor similar to 2 with respect to the extrapolationof the best-fitting 3-10 keV model. Additional Swift-BAT andIntegral-IBIS observations show that the 20-100 keV is concentratedwithin similar to 1.5 arcmin from the center of the galaxy, and is notsignificantly variable on timescales from days to years. A comparisonof this component with the 3-10 keV emission, which is characterized bya rapidly variable absorption, suggests a complex structure of thecircumnuclear medium, consisting of at least two distinct componentswith rather different physical properties, one of which covers >80% ofthe source with a column density N-H similar to 3-4x10(24) cm(-2). Analternative explanation is the presence of a double active nucleus inthe center of NGC 1365.

Search for the decay phi -> K0-K0bar-gamma with the KLOE experiment

2009-06-30T22:00:00Z

Search for the decay phi -> K0-K0bar-gamma with the KLOE experiment Ambrosino, F.; Antonelli, A.; Antonelli, M.; Archilli, F.; Beltrame, P.; Bencivenni, G.; Bertolucci, S.; Bini, C.; Bloise, C.; Bocchetta, Serena; Bossi, F.; Branchini, P.; Capon, G.; Capussela, T.; Ceradini, Filippo; Ciambrone, P.; De Lucia, E.; De Santis, A.; De Simone, P.; De Zorzi, G.; Denig, A.; Di Domenico, A.; Di Donato, C.; Di Micco, Biagio; Dreucci, M.; Felici, G.; Fiore, S.; Franzini, P.; Gatti, C.; Gauzzi, P.; Giovannella, S.; Graziani, E.; Lanfranchi, G.; Lee-Franzini, J.; Martini, M.; Massarotti, P.; Meola, S.; Miscetti, S.; Moulson, M.; Mueller, S.; Murtas, F.; Napolitano, M.; Nguyen, Federico; Palutan, M.; Pasqualucci, E.; Passeri, A.; Patera, V.; Santangelo, P.; Sciascia, B.; Spadaro, T.; Testa, M.; Tortora, L.; Valente, P.; Venanzoni, G.; Versaci, R.; Xu, G. 2009-07 Physics Letters B 679 10-14 We have searched for the decay phi -> K0-K0bar-gamma by detecting KS pairs plus a photon and with the KS-mesons decaying to pi+ pi-, in a sample of about 1.5 x 10^9 phi-decays collected by the KLOE experiment at DAFNE. The reaction proceeds through the intermediate states f0(980)-gamma, a0(980)-gamma. We find five events with 3.2 events expected from background processes. We obtain the upperlimit: BR(phi -> K0-Kobar-gamma < 1.9 x 10^(-8) at 90% CL.

The bolometric luminosity of type 2 AGN from extinction-corrected [OIII]: no evidence of Eddington-limited sources

2009-08-31T22:00:00Z

The bolometric luminosity of type 2 AGN from extinction-corrected [OIII]: no evidence of Eddington-limited sources Lamastra, Alessandra; Bianchi, Stefano; Matt, Giorgio; Perola, Giuseppe Cesare; Barcons, X.; Carrera, F. J. 2009-09 Astronomy & Astrophysics 504 73-79 Context. There have been recent claims that a significant fraction of type 2 AGN accrete close to or even above the Eddington limit. In type 2 AGN, the bolometric luminosity (L-b) is generally inferred from the [OIII] emission line luminosity (L-OIII). The key issue in estimating the bolometric luminosity in these AGN, is therefore to know the bolometric correction to be applied to L-OIII. A complication arises from the observed L-OIII being affected by extinction, most likely from dust within the narrow line region. The extinction-corrected [OIII] luminosity (L-OIII(c)) is a better estimator of the nuclear luminosity than L-OIII. However, only the bolometric correction to be applied to the uncorrected L-OIII has been evaluated so far. Aims. This paper is devoted to estimating the bolometric correction C-OIII = L-b/L-OIII(c) for deriving the Eddington ratios for the type 2 AGN in a sample of SDSS objects. Methods. We collected 61 sources from the literature with reliable estimates of both L-OIII(c) and X-ray luminosities (L-X). To estimate C-OIII, we combined the observed correlation between L-OIII(c) and L-Xwith the X-ray bolometric correction. Results. In contrast to previous studies, we found a linear correlation between L-OIII(c) and L-X. We estimated C-OIII using an earlier luminosity-dependent X-ray bolometric correction, and we found a mean value of C-OIII in the luminosity ranges log L-OIII = 38-40, 40-42, and 42-44 of 87, 142, and 454, respectively. We used it to calculate the Eddington ratio distribution of type 2 SDSS AGN at 0.3 < z < 0.4 and found that these sources are not accreting near their Eddington limit, contrary to previous claims.

A global fit to determine the pseudoscalar mixing angle and the gluonium content of the eta ' meson

2009-07-30T22:00:00Z

A global fit to determine the pseudoscalar mixing angle and the gluonium content of the eta ' meson Ambrosino, F.; Antonelli, A.; Antonelli, M.; Archilli, F.; Beltrame, P.; Bencivenni, G.; Bertolucci, S.; Bini, C.; Bloise, C.; Bocchetta, Simona; Bossi, F.; Branchini, Paolo; Capon, G.; Capussela, T.; Ceradini, Filippo; Ciambrone, P.; De Lucia, E.; De Santis, A.; De Simone, P.; De Zorzi, G.; Denig, A.; Di Domenico, A.; Di Donato, C.; Di Micco, Biagio; Dreucci, M.; Felici, G.; Fiore, S.; Franzini, P.; Gatti, C.; Gauzzi, P.; Giovannella, S.; Graziani, Enrico; Jacewicz, M.; Lanfranchi, G.; Lee-Franzini, J.; Martini, M.; Massarotti, P.; Meola, S.; Miscetti, S.; Moulson, M.; Mueller, S.; Murtas, F.; Napolitano, M.; Nguyen, Federico; Palutan, M.; Pasqualucci, E.; Passeri, Antonio; Patera, V.; Santangelo, P.; Sciascia, B.; Spadaro, T.; Testa, M.; Tortora, Ludovico; Valente, P.; Venanzoni, G.; Versaci, R.; Xu, G. 2009-07-31 Journal of High Energy Physics 7 105 We update the values of the eta-eta' mixing angle and of the eta' gluonium content by fitting our measurement R-phi = BR(phi -> etagamma)/BR(phi -> eta gamma) together with several vector meson radiative decays to pseudoscalars (V -> P gamma), pseudoscalar mesons radiative decays to vectors (P -> V gamma) and the eta' -> gamma gamma,pi(0) -> gamma gamma widths. From the fit we extract a gluonium fraction of Z(G)(2) = 0.12 +/- 0.04, the pseudoscalar mixing angle psi(P) = (40.4 +/- 0.6) degrees and the phi - omega mixing angle psi(V)= (3.32 +/- 0.09)degrees. Z(G)(2) and psi(P) are fairly consistent with those previously published. We also evaluate the impact on the eta' gluonium content determination of future experimental improvements of the eta' branching ratios and decay width.

Improved determination of the CKM Angle α from B --> π π decays

2007-06-30T22:00:00Z

Improved determination of the CKM Angle α from B --> π π decays UTfit Collaboration; Bona, M.; Ciuchini, Marco; Franco, E.; Lubicz, Vittorio; Martinelli, G.; Parodi, F.; Pierini, M.; Roudeau, P.; Schiavi, C.; Silvestrini, L.; Sordini, V.; Stocchi, A.; Vagnoni, V. 2007-07 Physical Review D 76 014015-014015-10 Motivated by a recent paper that compares the results of the analysis of the CKM angle alpha in the frequentist and in the Bayesian approaches, we have reconsidered the information on the hadronic amplitudes, which helps in constraining the value of alpha in the standard model. We find that the Bayesian method gives consistent results irrespective of the parametrization of the hadronic amplitudes and that the results of the frequentist and Bayesian approaches are equivalent when comparing meaningful probability ranges or confidence levels. We also find that from B-->pipi decays alone the 95% probability region for alpha is the interval [80°, 170°], well consistent with recent analyses of the unitarity triangle where, by using all the available experimental and theoretical information, one gets alpha=(93±4)°. Last but not least, by using simple arguments on the hadronic matrix elements, we show that the unphysical region alpha~0, present in several experimental analyses, can be eliminated.

Comment on "Excess of Proton Mean Kinetic Energy in Supercooled Water'' Reply

2009-07-31T22:00:00Z

Comment on "Excess of Proton Mean Kinetic Energy in Supercooled Water'' Reply Pietropaolo, A.; Senesi, R.; Andreani, C.; Botti, Alberto; Ricci, Maria Antonietta; Bruni, Fabio 2009-08 Physical Review Letters 103 069802 Comment on "Excess of Proton Mean Kinetic Energy in Supercooled Water'' Reply. A Reply to the Comment by A. K. Soper.

D--Dbar Mixing and New Physics: General Considerations and Constraints on the MSSM

2007-10-31T23:00:00Z

D--Dbar Mixing and New Physics: General Considerations and Constraints on the MSSM Ciuchini, Marco; Franco, E.; Guadagnoli, D.; Lubicz, V.; Pierini, M.; Porretti, V.; Silvestrini, L. 2007-11 Physics Letters B 655 162-166 Combining the recent experimental evidence of D--Dbar mixing, we extract model-independent information on the mixing amplitude and on its CP-violating phase. Using this information, we present new constraints on the flavour structure of up-type squark mass matrices in supersymmetric extensions of the Standard Model.

Model-independent Constraints on ΔF=2 Operators and the Scale of New Physics

2008-02-29T23:00:00Z

Model-independent Constraints on ΔF=2 Operators and the Scale of New Physics UTfit Collaboration; Bona, M.; Ciuchini, Marco; Franco, E.; Lubicz, V.; Martinelli, G.; Parodi, F.; Pierini, M.; Roudeau, P.; Schiavi, C.; Silvestrini, L.; Sordini, V.; Stocchi, A.; Vagnoni, V. 2008-03 Journal of High Energy Physics 03 1-23 We update the constraints on new-physics contributions to ΔF = 2 processes from the generalized unitarity triangle analysis, including the most recent experimental developments. Based on these constraints, we derive upper bounds on the coefficients of the most general ΔF = 2 effective Hamiltonian. These upper bounds can be translated into lower bounds on the scale of new physics that contributes to these low-energy effective interactions. We point out that, due to the enhancement in the renormalization group evolution and in the matrix elements, the coefficients of non-standard operators are much more constrained than the coefficient of the operator present in the Standard Model. Therefore, the scale of new physics in models that generate new ΔF = 2 operators, such as next-to-minimal flavour violation, has to be much higher than the scale of minimal flavour violation, and it most probably lies beyond the reach of direct searches at the LHC.