Measuring the prompt atmospheric neutrino flux with down-going muons in neutrino telescopes

In the TeV energy region and above, the uncertainty in the level of prompt atmospheric neutrinos would limit the search for diffuse astrophysical neutrinos. We suggest that neutrino telescopes may provide an empirical determination of the flux of prompt atmospheric electron and muon neutrinos by measuring the flux of prompt down-going muons. Our suggestion is based on the consideration that prompt neutrino and prompt muon fluxes at sea level are almost identical.Comment: 4 pages, 3 figure

Scuola, Università e Mercato del lavoro dopo la Riforma Biagi. Le politiche per la transizione dai percorsi educativi e formativi al mercato del lavoro

Quale ruolo per i percorsi di educazione e formazione nella riforma del mercato del lavoro? Se ne è parlato poco, in questi ultimi tempi. Eppure, nell’impianto della legge Biagi, proprio il sistema di istruzione e quello della formazione professionale rappresentano, assieme al nuovo contratto di apprendistato, il principale canale di sviluppo e valorizzazione delle risorse umane. Un canale attraverso cui avvicinare, grazie a investimenti in ricerca, innovazione e capitale umano, le performances del nostro sistema economico-produttivo a quelle degli altri Paesi europei. E non poteva essere diversamente, in una Europa che, da Lisbona in poi, dichiara enfaticamente di voler diventare l’economia basata sulla conoscenza più competitiva e dinamica del mondo. Il ritardo dell’Italia rispetto agli altri Stati europei è, da questo punto di vista, ancora impressionante. È sufficiente ricordare, al riguardo, come i tradizionali percorsi didattici e formativi abbiano sin qui determinato alti tassi di dispersione e, quel che più è grave, un ingresso tardivo nel mercato del lavoro. Le rilevazioni statistiche parlano di 28 anni, quando la media europea è attestata intorno ai 22-23 anni. È da tempo che se ne discute, senza tuttavia approdare a esiti concreti: gli istituti scolastici e le università italiane devono accelerare i processi volti a rafforzare la coerenza tra formazione erogata e fabbisogni del mercato del lavoro. La riforma universitaria che prevede la laurea triennale è entrata in vigore con l’anno accademico 2001/2002, i primi laureati tuttavia in minima parte si sono avvicinati al mondo del lavoro ma hanno proseguito il corso di studi verso la laurea specialistica e quindi se questa tendenza verrà confermata, difficilmente nel nostro Paese ci avvicineremo alla media europea e continueremo ad avere laureati in cerca di prima occupazione ad un’età troppo elevata per rispondere ai bisogni del mercato del lavoro

Relevance of Ion-Channeling for Direct DM Detection

The channeling of the recoiling nucleus in crystalline detectors after a WIMP collision would produce a larger scintillation or ionization signal in direct detection experiments than otherwise expected. I present estimates of the importance of this effect for the total direct detection rate and the daily modulation of the signal using analytic models produced in the 1960's and 70's to describe the effects of channeling and blocking in crystals.Comment: Talk given at the TAUP 2009 conference, Rome, Italy, July 1-5 2009. 3 pages, 4 figures. jpconf.cls and jpconf11.clo files need to typeset the tex fil

Search for photons at the Pierre Auger Observatory

The Pierre Auger Observatory has a unique potential to search for ultra-high energy photons (above ~1 EeV). First experimental limits on photons were obtained during construction of the southern part of the Observatory. Remarkably, already these limits have proven useful to falsify proposals about the origin of cosmic rays, and to perform fundamental physics by constraining Lorentz violation. A final discovery of photons at the upper end of the electromagnetic spectrum is likely to impact various branches of physics and astronomy.Comment: 5 pages, 5 figures. Presented at CRIS 2008, Malfa, Ital

Cold dark matter in brane cosmology scenario

We analyze the dark matter problem in the context of brane cosmology. We investigate the impact of the non-conventional brane cosmology on the relic abundance of non-relativistic stable particles in high and low reheating scenarios. We show that in case of high reheating temperature, the brane cosmology may enhance the dark matter relic density by many order of magnitudes and a stringent lower bound on the five dimensional scale is obtained. We also consider low reheating temperature scenarios with chemical equilibrium and non-equilibrium. We emphasize that in non-equilibrium case, the resulting relic density is very small. While with equilibrium, it is increased by a factor of O(10^2) with respect to the standard thermal production. Therefore, dark matter particles with large cross section, which is favored by detection expirements, can be consistent with the recent relic density observational limits.Comment: 14 pages, 1 figur

The Standard Model of Leptons as a Purely Vectorial Theory

We propose a way to reconcile the Standard Model of leptons with a purely vectorial theory. The observed neutrino is predicted to be massless. The unobservability of its partner and the $V-A$ structure of the weak currents are given the same origin.Comment: 10 pages. Latex, 8 postscript figures included. We have corrected 2 (cancelling) sign misprints, and made explicit that we also recover the usual couplings of the U(1) gauge field B. The conclusions are unchanged. PAR-LPTHE 93/1

Measurement of the gluon PDF at small x with neutrino telescopes

We analyze the possibility that neutrino telescopes may provide an experimental determination of the slope lambda of the gluon distribution in the proton at momentum fractions x smaller than the accelerator reach. The method is based on a linear relation between lambda and the spectral index (slope) of the down-going atmospheric muon flux above 100 TeV, for which there is no background. Considering the uncertainties in the charm production cross section and in the cosmic ray composition, we estimate the error on the measurement of lambda through this method, excluding the experimental error of the telescopes, to be ~ +/- 0.2Comment: 16 pages with 16 figures - new version, comments added, same results and figure

Anomaly mediated SUSY breaking scenarios in the light of cosmology and in the dark (matter)

Anomaly mediation is a popular and well motivated supersymmetry breaking scenario. Different possible detailed realisations of this set-up are studied and actively searched for at colliders. Apart from limits coming from flavour, low energy physics and direct collider searches, these models are usually constrained by the requirement of reproducing the observations on dark matter density in the universe. We reanalyse these bounds and in particular we focus on the dark matter bounds both considering the standard cosmological model and alternative cosmological scenarios. These scenarios do not change the observable cosmology but relic dark matter density bounds strongly depend on them. We consider few benchmark points excluded by standard cosmology dark matter bounds and suggest that loosening the dark matter constraints is necessary in order to avoid a too strong (cosmological) model dependence in the limits that are obtained for these models. We also discuss briefly the implications for phenomenology and in particular at the Large Hadron Collider.Comment: 37 pages, 20 figures, 1 tabl

On the measurement of the proton-air cross section using longitudinal shower profiles

In this paper, we will discuss the prospects of deducing the proton-air cross section from fluorescence telescope measurements of extensive air showers. As it is not possible to observe the point of first interaction $X_{\rm 1}$ directly, other observables closely linked to $X_{\rm 1}$ must be inferred from the longitudinal profiles. This introduces a dependence on the models used to describe the shower development. The most straightforward candidate for a good correlation to $X_{\rm 1}$ is the depth of shower maximum $X_{\rm max}$. We will discuss the sensitivity of an $X_{\rm max}$-based analysis on $\sigma_{\rm p-air}$ and quantify the systematic uncertainties arising from the model dependence, parameters of the reconstruction method itself and a possible non-proton contamination of the selected shower sample.Comment: 4 pages, Proceedings for ISVHECRI Weihei 200