447 research outputs found
Hadronic mass and q^2 moments of charmless semileptonic B decay distributions
We report OPE predictions for hadronic mass and q^2 moments in inclusive
semileptonic B decays without charm, taking into account experimental cuts on
the charged lepton energy and on the hadronic invariant mass, and address the
related theoretical uncertainty.Comment: 16 pages, 1 figure; v3: we have corrected a mistake in the code that
produced the numerical results; tables replaced, small changes in the tex
A Teledentistry System for the Second Opinion
In this paper we present a teledentistry system aimed to the Second Opinion task. It make use of a particular camera called intra-oral camera, also called dental camera, in
order to perform the photo shooting and real-time video of the inner part of the mouth. The pictures acquired by the Operator with such a device are sent to the Oral Medicine Expert (OME)
by means of a current File Transfer Protocol (FTP) service and the real-time video is channeled into a video streaming thanks to the VideoLan client/server (VLC) application. It is composed by a HTML5 web-pages generated by PHP and allows to perform
the Second Opinion both when Operator and OME are logged and when one of them is offline
Brief review on semileptonic B decays
We concisely review semileptonic B decays, focussing on recent progress on
both theoretical and experimental sides.Comment: 18 pages, 2 figures; version to be published in Mod. Phys. Lett.
Physics at the Linear Collider
The physics at the planned colliders is discussed around three main
topics corresponding to different manifestations of symmetry breaking:
physics in the no Higgs scenario, studies of the properties of the Higgs and
precision tests of SUSY. A comparison with the LHC is made for all these cases.
The mode of the linear collider will also be reviewed.Comment: 31 pages, 12 figures. Invited talk given at the Fifth Workshop on
High Energy Physics Phenomenology, Inter-University Centre for Astronomy and
Astrophysics, Pune, India, January 12 - 26, 199
Physical renormalization condition for the quark-mixing matrix
We investigate the renormalization of the quark-mixing matrix in the
Electroweak Standard Model. We show that the corresponding counterterms must be
gauge independent as a consequence of extended BRS invariance. Using rigid
SU(2)_L symmetry, we proof that the ultraviolet-divergent parts of the
invariant counterterms are related to the field renormalization constants of
the quark fields. We point out that for a general class of renormalization
schemes rigid SU(2)_L symmetry cannot be preserved in its classical form, but
is renormalized by finite counterterms. Finally, we discuss a genuine physical
renormalization condition for the quark-mixing matrix that is gauge independent
and does not destroy the symmetry between quark generations.Comment: 20 pages, LaTeX, minor changes, references adde
Flavour Mixing, Gauge Invariance and Wave-function Renormalisation
We clarify some aspects of the LSZ formalism and wave function
renormalisation for unstable particles in the presence of electroweak
interactions when mixing and CP violation are considered. We also analyse the
renormalisation of the CKM mixing matrix which is closely related to wave
function renormalisation. We critically review earlier attempts to define a set
of "on-shell" wave function renormalisation constants. With the aid of an
extensive use of the Nielsen identities complemented by explicit calculations
we corroborate that the counter term for the CKM mixing matrix must be
explicitly gauge independent and demonstrate that the commonly used
prescription for the wave function renormalisation constants leads to gauge
parameter dependent amplitudes, even if the CKM counter term is gauge invariant
as required. We show that a proper LSZ-compliant prescription leads to gauge
independent amplitudes. The resulting wave function renormalisation constants
necessarily possess absorptive parts, but we verify that they comply with the
expected requirements concerning CP and CPT. The results obtained using this
prescription are different (even at the level of the modulus squared of the
amplitude) from the ones neglecting the absorptive parts in the case of top
decay. The difference is numerically relevant.Comment: 19 pages, plain latex, one ps figur
Tilt measurements at Vulcano Island
A network of tiltmeters has been operational on Vulcano Island for numerous years. At present, the network comprises five functioning borehole stations, four of which are installed at 8-10 m and allow recording very stable, high precision signals with very low noise.
We report observations over the last 12 years that illustrate impulsive variations linked to seismicity and long-term (several years) trends in the signals. We suggest a relationship between tilt changes correlated to the strongest regional seismic events and site acceleration; long-term tilt variations analyzed in combination with other ground deformation data seem to represent the evidence of a contraction of the La Fossa cone.
We also analyzed how the tilt device has the capability to detect possible magma migrations; we considered previous studies that have imaged spatially well-defined levels of magma accumulation beneath La Fossa, and Vulcanello; we concluded that the Vulcano tilt network should be capable of detecting the upward migration of small magma volumes.
Finally, we show that no evidence of changes are visible on tilt signals during anomalous degassing episodes (linked to a building up input of magmatic fluids) at the La Fossa thereby evidencing that no magma migration occurred during such events
Caratterizzazione sismica del sistema strutturale Pernicana - Provenzana (settore NE dell'Etna) attraverso l'utilizzo di differenti tecniche di rilocalizzazione.
Il fianco nord-orientale dellâEtna Ăš interessato da un noto sistema strutturale denominato Pernicana-Provenzana, che ha un andamento WNWâESE. Esso Ăš collegato ad ovest ad un altro importante elemento strutturale, il Rift di Nord-Est, che mostra avere un ruolo importante nel controllo dei fenomeni di instabilitĂ del fianco orientale del vulcano. La sismicitĂ associata a questo sistema strutturale Ăš di tipo superficiale (max 2-3 km b.s.l.) e rilevanti fenomeni di creeping sono rilevabili sul suo segmento orientale. I terremoti associati a questo sistema di faglie, che possono raggiungere magnitudo sino a 4.3, qualche volta con fenomeni di fagliazione superficiale, hanno provocato danni importanti alle principali strutture alberghiere ed ai paesi ubicati in prossimitĂ della struttura.
Nel presente lavoro, sono riportati i risultati di uno studio di dettaglio della sismicitĂ localizzata lungo tale sistema strutturale, nel periodo 1999-2009. I terremoti registrati dalla rete sismica permanente dellâIstituto Nazionale di Geofisica e Vulcanologia â Sezione di Catania, localizzati con un modello 1D utilizzando lâalgoritmo Hypoellipse (Gruppo Analisi Dati Sismici, 2010), sono stati rilocalizzati applicando due differenti tecniche di localizzazione: NonLinLoc sviluppato da Lomax et al. (2000) e HypoDD proposto da Waldhauser & Ellsworth (2000). La prima metodologia Ăš basata su un processo di ricerca globale, nello spazio 3D, dei parametri di localizzazione che possono essere ottenuti utilizzando diversi algoritmi. Il metodo HypoDD, che non prevede lâutilizzo di un modello 3D, Ăš invece basato sullâalgoritmo della doppia differenza che minimizza i residui tra le differenze dei traveltime osservati e calcolati per coppie di terremoti a stazioni comuni. Lâapplicazione di tali tecniche ha permesso di ottenere localizzazioni ipocentrali di migliore qualitĂ , fondamentali per la caratterizzazione sismica della struttura.
Lâapplicazione di queste differenti metodologie ha permesso di evidenziare che il sistema strutturale Pernicana- Provenzana risulta composto da segmenti caratterizzati da differenti rilasci di energia sismica. Sono stati individuati due cluster principali di terremoti, la cui distribuzione spaziale ha evidenziato un differente verso nellâimmersione dei piani di faglia collegabili a questa sismicitĂ . Infine, lâapplicazione di tecniche di cross-correlazione delle forme dâonda registrate nel periodo indagato ha consentito di individuare âfamiglieâ di terremoti.
Lâanalisi spazio â temporale delle famiglie individuate ha evidenziato per alcune di esse, una ricorrenza temporale ed ha permesso di ipotizzare che lâapplicazione di un campo di stress sul sistema Pernicana-Provenzana potrebbe essere capace di attivare le stesse sorgenti sismiche in differenti periodi
Gauge-independent renormalization in the 2HDM
We present a consistent renormalization scheme for the CP-conserving
Two-Higgs-Doublet Model based on renormalization of the mixing
angles and the soft--symmetry-breaking scale in the Higgs sector.
This scheme requires to treat tadpoles fully consistently in all steps of the
calculation in order to provide gauge-independent -matrix elements. We show
how bare physical parameters have to be defined and verify the gauge
independence of physical quantities by explicit calculations in a general
-gauge. The procedure is straightforward and applicable to other
models with extended Higgs sectors. In contrast to the proposed scheme, the
renormalization of the mixing angles combined with popular
on-shell renormalization schemes gives rise to gauge-dependent results already
at the one-loop level. We present explicit results for electroweak NLO
corrections to selected processes in the appropriately renormalized
Two-Higgs-Doublet Model and in particular discuss their scale dependence.Comment: 52 pages, PDFLaTeX, PDF figures, JHEP version with Eq. (5.23)
correcte
Charm Quark Contribution to K+ -> pi+ nu anti-nu at Next-to-Next-to-Leading Order
We calculate the complete NNLO QCD corrections to the charm contribution of
the rare decay K+ -> pi+ nu nu-bar. We encounter several new features, which
were absent in lower orders. We discuss them in detail and present the results
for the 2-loop matching conditions of the Wilson coefficients, the 3-loop
anomalous dimensions, and the 2-loop matrix elements of the relevant operators
that enter the NNLO renormalization group analysis of the Z-penguin and the
electroweak box contribution. The inclusion of the NNLO QCD corrections leads
to a significant reduction of the theoretical uncertainty from 9.8% down to
2.4% in the relevant parameter Pc, implying the leftover scale uncertainties in
BR(K+ -> pi+ nu nu-bar) and in the determination of |V_td|, sin(2 beta), and
gamma from the K -> pi nu nu system to be 1.3%, 1.0%, 0.006, and 1.2 degrees,
respectively. For the charm quark MSbar mass mc=(1.30+-0.05) GeV and |V_us|=
0.2248 the NLO value Pc=0.37+-0.06 is modified to Pc=0.38+-0.04 at the NNLO
level with the latter error fully dominated by the uncertainty in mc. We
present tables for Pc as a function of mc and alphas(MZ) and a very accurate
analytic formula that summarizes these two dependences as well as the dominant
theoretical uncertainties. Adding the recently calculated long-distance
contributions we find BR(K+ -> pi+ nu nu-bar)=(8.0+-1.1)*10^-11 with the
present uncertainties in mc and the Cabibbo-Kobayashi-Maskawa elements being
the dominant individual sources in the quoted error. We also emphasize that
improved calculations of the long-distance contributions to K+ -> pi+ nu nu-bar
and of the isospin breaking corrections in the evaluation of the weak current
matrix elements from K+ -> pi0 e+ nu would be valuable in order to increase the
potential of the two golden K -> pi nu nu decays in the search for new physics.Comment: 74 pages, 28 figures. Erratum added: We correct the treatment of
anomalous triangle diagrams. The associated numerical correction is below a
permille; v3: Typographical mistakes in (108), (111) and (112) corrected.
Thanks to Xu Feng for pointing them out. Numerical results unchange
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