The Higgs boson from an extended symmetry

The variety of ideas put forward in the context of a "composite" picture for the Higgs boson calls for a simple and effective description of the related phenomenology. Such a description is given here by means of a "minimal" model and is explicitly applied to the example of a Higgs-top sector from an SO(5) symmetry. We discuss the spectrum, the ElectroWeak Precision Tests, B-physics and naturalness. We show the difficulty to comply with the different constraints. The extended gauge sector relative to the standard SU(2)xU(1), if there is any, has little or no impact on these considerations. We also discuss the relation of the "minimal" model with its "little Higgs" or "holographic" extensions based on the same symmetry.Comment: 22 pp; v3: Small corrections, version to be published in Phys. Rev.

The becoming of a Prehistoric Landscape: Palaeolithic Occupations and Geomorphological Processes at Lojanik (Serbia)

Accomplishing long-term plans to harvest and modify natural resources has been a crucial skill for the survival of our species since early Prehistory. Research on this first step of production mostly focuses on the provenience study of lithic artifacts uncovered at archaeological sites, using petrographic and geochemical analyses to correlate the artifacts with potential geological outcrops. Although fundamental for understanding key aspects of landscape use and mobility, regional raw material economy, and extraction technology, Palaeolithic raw material sources have been less intensively investigated, as they are often difficult to locate and challenging to tackle with traditional archaeological approaches. Lojanik in the Central Balkans is one of the largest Prehistoric quarrying areas known in Europe, showing numerous lithic raw material outcrops exploited from the Middle Palaeolithic to the Chalcolithic periods, over an area of 18 hectares. In this paper, we present the results from our renewed research program in this region. Combining airborne LIDAR mapping, geomorphological and archaeological survey, and techno-typological analysis of lithic artifacts, we were able to reconstruct the geomorphological evolution of the landscape and its use by prehistoric societies.info:eu-repo/semantics/publishedVersio

Interpreting gaps: a geoarchaeological point of view on the Gravettian record of Ach and Lone valleys (Swabian Jura, SW Germany)

Unlike other Upper Paleolithic industries, Gravettian assemblages from the Swabian Jura are documented solely in the Ach Valley (35-30 Kcal BP). On the other hand, traces of contemporaneous occupations in the nearby Lone Valley are sparse. It is debated whether this gap is due to a phase of human depopulation, or taphonomic issues related with landscape changes. In this paper we present ERT, EC-logging and GPR data showing that in both Ach and Lone valleys sediments and archaeological materials eroded from caves and deposited above river incisions after 37-32 Kcal BP. We argued that the rate of cave erosion was higher after phases of downcutting, when hillside erosion was more intensive. To investigate on the causes responsible for the dearth of Gravettian materials in the Lone Valley we test two alternative hypotheses: i) Gravettian humans occupied less intensively this part of the Swabian Jura. ii) Erosion of cave deposits did not occur at the same time in the two valleys. We conclude that the second hypothesis is most likely. Ages from the Lone Valley show increasing multimillennial gaps between 36 and 18 Kcal BP, while a similar gap is present in the Ach Valley between 28 and 16 Kcal BP. Based on geoarchaeological data from previous studies and presented in this paper, we interpreted these gaps in radiocarbon data as indicating of cave erosion. Furthermore, we argued that the time difference across the two valleys show that the erosion of cave deposits began and terminated earlier in the Lone Valley, resulting in a more intensive removal of Gravettian-aged deposits. The hypothesis that cave erosion was triggered by regional landscape changes seems to be supported by geochronological data from the Danube Valley, which show that terrace formation at the end of the Pleistocene moved westwards throughout southern Germany with a time lag of few millennia.PTDC/HAR-ARQ/27833/2017info:eu-repo/semantics/publishedVersio

Hunter-gatherer environments at the Late Pleistocene sites of Mwanganda's Village and Bruce, northern Malawi

Mwanganda's Village (MGD) and Bruce (BRU) are two open-air site complexes in northern Malawi with deposits dating to between 15 and 58 thousand years ago (ka) and containing Middle Stone Age (MSA) lithic assemblages. The sites have been known since 1966 and 1965, respectively, but lacked chronometric and site formation data necessary for their interpretation. The area hosts a rich stone artifact record, eroding from and found within alluvial fan deposits exhibiting poor preservation of organic materials. Although this generally limits opportunities for site-based environmental reconstructions, MGD and BRU are located at the distal margins of the alluvial fan, where lacustrine lagoonal deposits were overprinted by a calcrete paleosol. This has created locally improved organic preservation and allowed us to obtain ecological data from pollen, phytoliths, and pedogenic carbonates, producing a regional- to site-scale environmental context for periods of site use and abandonment. Here, we integrate the ecological data into a detailed site formation history, based on field observations and micromorphology, supplemented by cathodoluminescence microscopy and μ-XRF. By comparing local, on-site environmental proxies with more regional indicators, we can better evaluate how MSA hunter-gatherers made decisions about the use of resources across the landscape. Our data indicate that while tree cover similar to modern miombo woodland and evergreen gallery forest prevailed at most times, MSA hunter-gatherers chose more locally open environments for activities that resulted in a lithic artifact record at multiple locations between 51 and 15 ka.publishedVersio

Composite GUTs: models and expectations at the LHC

We investigate grand unified theories (GUTs) in scenarios where electroweak (EW) symmetry breaking is triggered by a light composite Higgs, arising as a Nambu-Goldstone boson from a strongly interacting sector. The evolution of the standard model (SM) gauge couplings can be predicted at leading order, if the global symmetry of the composite sector is a simple group G that contains the SM gauge group. It was noticed that, if the right-handed top quark is also composite, precision gauge unification can be achieved. We build minimal consistent models for a composite sector with these properties, thus demonstrating how composite GUTs may represent an alternative to supersymmetric GUTs. Taking into account the new contributions to the EW precision parameters, we compute the Higgs effective potential and prove that it realizes consistently EW symmetry breaking with little fine-tuning. The G group structure and the requirement of proton stability determine the nature of the light composite states accompanying the Higgs and the top quark: a coloured triplet scalar and several vector-like fermions with exotic quantum numbers. We analyse the signatures of these composite partners at hadron colliders: distinctive final states contain multiple top and bottom quarks, either alone or accompanied by a heavy stable charged particle, or by missing transverse energy.Comment: 55 pages, 13 figures, final version to be published in JHE

Landscape changes, cave site formation and human occupation during the Late Pleistocene: a geoarchaeological study from the Ach and Lone valleys (Swabian Jura, SW Germany)

In the Swabian Jura (Southwest Germany) the Ach and Lone valleys host a number of cave sites, which have been repeatedly occupied by groups of hominins since at least the last interglacial. From the excavation of these Prehistoric cave deposits generations of archaeologists have discovered deep sequences and spectacular finds that help to illuminate the evolution of our species and the extinction of Neanderthals. The current understanding of the relationship between caves, cave deposits, human occupation and landscape evolution in the Ach and Lone valleys relies on data coming almost exclusively from cave sites and rockshelters. Conversely, the few geological studies that focused on the geomorphological evolution of the Ach and Lone valleys were mostly designed to answer questions unrelated to the study of the human occupation of this region. This dissertation intends to bridge the gap existing (not only in the Ach and Lone valleys) between the micromorphological analysis of cave deposits and the study of the paleolandscape. To this end, we investigated the deposits accumulated inside the cave site of Hohlenstein-Stadel (in the Lone Valley) with micromorphological analysis and FTIR methods. Additionally we studied the sediment archives preserved in the Ach and Lone valleys by means of auggering, deeper coring, geophysics, micromorphology, FTIR and 14C dating. By integrating our results with previous studies we have been able to evaluate the impact of landscape and environmental changes on the sedimentary and diagenetical processes that occurred inside the cave sites of this region. Our findings carry significant implications for models used to explain the arrival of early modern humans in the Swabian Jura and the human depopulation that this region seem to have experienced around the Last Glacial Maximum (LGM). Previous studies have argued that the early Aurignacian deposits at the sites of Hohle Fels and Geißenklösterle are characterized by deposition of fresh loess, less intensive phosphatization, and the formation of ice lenses. These data support the hypothesis that modern humans entered the Ach Valley in the course of a period characterized by cold climate. Our micromorphological analysis showed that inside Hohlenstein-Stadel (in the Lone Valley) the transition from the Middle Paleolithic to early Aurignacian deposits displays decreasing phosphatization. However, at Hohlenstein-Stadel we did not observe features diagnostic for ground freezing (such as ice lenses). Therefore inside this cave there is no direct evidence supporting the occurrence of a colder climatic period at the time of the arrival of modern humans. The data we collected from Ach and Lone valleys suggest that this region has been variably shaped by phases of soil formation, soil denudation, loess accumulation and river valley incision. Our study revealed that these changes in the landscape might have shaped significantly the archaeological record originally accumulated inside the cave sites of this region. Accordingly to a widely accepted model, Southwest Germany was abandoned by Gravettian groups around 26.000 14C BP. After a major chronostratigraphic gap Magdalenians recolonized the region starting 13.500 14C BP. Such chronostratigraphic gap (12.500 14C years) have been regarded as indicative of the depopulation that the region experienced during the LGM. Our data, however, show that the beginning of this long-lasting phase of apparent depopulation coincides with the occurrence of erosional phases at some cave sites of Ach and Lone valleys. Although the relation between cave erosion and Gravettian emigration needs to be further verified, we hypothesize that humans might have been present in this region also during the period 26.000-13.500 14C BP and erosional processes might have cancelled the archaeological evidence for such occupations

Come cambia il mondo. Storie di lingue, testi e uomini in onore di Lorenzo Renzi, Atti del Convegno (Padova 15-16 gennaio 2019)

Questo piccolo libro collettivo – nutrito da rigorosi specialismi ma sempre percorso da un’idea viva e calda di umanesimo integrale – nasce come dono e segno di riconoscenza per i magnifici ottant’anni di Lorenzo Renzi, secondo una formula che riprende e incrocia diversi modi e tipi della Festschrift accademica. Del classico volume omaggiale si trattiene qui l’affettuosa coutume che spinge a tornare su temi e campi di studio inaugurati o abitualmente frequentati dal Festeggiato, ma nel sommario figurano anche contributi di consuntivo e di approfondimento deliberatamente centrati sull’opera di Renzi, oppure interventi che, muovendo dalle sue indagini e dai suoi cantieri più rappresentativi, fanno leva su acquisti ed esiti già consolidati per rilanciare la ricerca verso nuove piste e risultati ulteriori. E non mancano spunti e affondi sull’ethos e sullo stile di lavoro di Renzi, sempre però con una visione alta e impegnata, che non si trivializza nell’aneddotico, bensì mette enfasi sulla relazione forte con i metodi, le discussioni teoriche, le correnti intellettuali e il dibattito sulle idee. La table des matières è ben lungi dal restituire la fastosa varietà dei percorsi e delle curiosità di Renzi, ma quanto meno allude per cenni a questa complessità, radunando saggi di linguistica, letteratura, metrica, storia della critica e delle relazioni culturali, con un amplissimo orizzonte di curvature e di aperture interdisciplinari, che ricomprende anche le assidue attenzioni riservate dal Nostro all’insegnamento della filologia romanza e alla manualistica universitaria. Un quadro in apparenza dispersivo nella sua effervescenza centrifuga, ma armoniosamente ricomposto nella personalità effusiva e ricchissima di un maestro della romanistica, che segue con passione i mutamenti del mondo e non esclude dal cerchio dei suoi interessi nessun aspetto dell’umano