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1) Precision Diboson Observables for the LHC – 2) Photon Jets

1) Precision Diboson Observables for the LHC Motivated by the restoration of SU(2)×U(1) at high energy, we suggest that certain ratios of diboson differential cross sections can be used as high-precision observables at the LHC. We rewrite leading-order diboson partonic cross sections in a form that makes their SU(2)×U(1)and custodial SU(2) structure more explicit than in previous literature, and identify important aspects of this structure that survive even in hadronic cross sections. We then focus on higher-order corrections to ratios of γγ, Zγ and ZZ processes, including full next-to-leading-order corrections and gg initial-state contributions, and argue that these ratios can likely be predicted to better than 5%, which should make them useful in searches for new phenomena. The ratio of Zγ to γγ is especially promising in the near term, due to large rates and to exceptional cancellations of QCD-related uncertainties. 2) Photon Jets Photon Jets are beams of collimated photons that may appear as a single (poorly isolated) photon to calorimeters at LHC. Several recent articles suggested that the recent 750 GeV excess at LHC may be explained as pairs of Photon Jets rather than pairs of photons. I will briefly introduce the excess and then proceed to highlight some of the tools that we might find useful to discriminate between photons, neutral pion rich hadronic jets and Photon Jets.

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Non-interferometric experimental tests of macroscopic spatial quantum superposition

Abstract: Is quantum superpostion an exact principle of nature? Recent progress in technological developments allow to explore the quantum properties of very complex systems, bringing the question of whether also macroscopic systems share such features, within experimental reach. It seems feasible to generate for instance quantum superposition states of particles of mass of one million amu (atomic mass unit) [1]. The interest in such experiments is increased by the fact that, on the theory side, some suggest that the quantum superposition principle is not exact, departures from it being the larger, the more macroscopic the system [2].    We will report on new ideas to experimentally test the superposition principle with non-interferometric methods. Testing the superposition principle intrinsically also means to test suggested extensions of quantum theory. For instance collapse models predict a heating effect, which results in a Brownian-like random motion of any isolated particle in space. The heating can be monitored using optomechanical systems even in the classical regime, if competing sources of heat can be reduced sufficiently. We will emphasise levitated optomechanical systems and discuss the possibility to test the heating effect by detecting the motion of the particle in space [4] as well as in the frequency domain where heating is manifested as increase of the spectral feature [5].   We will show quantitative calculations for experiments in both regimes and compare to the state-of-the-art. We will also report on the status of our experiments on optical levitation and parametric feedback cooling of the 3d motion ...

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Challenges in the Dark Sector: Alternatives to the WIMP paradigm

Aim of the workshop: Identifying what Dark Matter (DM) is, as well as its nature and properties, remains a major challenge for both theoretical and experimental astroparticle physics communities. In the past decades, Weakly Interacting Massive Particle (WIMP) DM has been the most hunted candidate, with the result that nowadays WIMPs are cornered by large amounts of experimental data from Direct Detection, Indirect Detection and Collider Experiments. If no WIMP signal is detected in the next few years, the possibility that this very appealing theoretical idea is not what Nature has chosen will become even more compelling and will boost theoretical studies and experimental searches for non-WIMP alternatives for DM. The aim of this 3-day meeting is to convene experts on alternatives to the WIMP paradigm to stimulate informal discussions on different possibilities (dark photons, axion-like particles, Majorons, self-interacting dark sectors, just to mention a few). We plan to have only three or four talks each day and plenty of time to discuss implications of these DM scenarios, experimental search strategies, new theoretical proposals, and out-of-mainstream ideas. The general approach and format of the talks will be pedagogical and aimed at favoring extended discussions among all participants. The audience will range from theorists who are expert on related topics to skillful experimentalists planning new non-WIMP detection experiments, as well as postdocs, graduate students and non-expert colleagues working in different areas. Speakers: J. Beacham (Ohio State U. & CERN) “Lost in a Dark Photon Wood: Searches for hidden light gauge bosons ...

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Observations of astrophysical objects which cannot exist.

Recently astronomical data are accumulated, reporting discoveries of very early formed objects, such as supermassive black holes (quasars), gamma bursters, supernovae, and very bright galaxies at high redshifts. Moreover, there is an evidence to existence of starts in our Galaxy which are too old, even older than the universe. All such objects cannot be created in the frameworks of accepted scenarios of their formation. An origin of supermassive black holes observed in the centers of many (maybe all) large and some small galaxies also remains mysterious. After a review of the observations a model is presented that can explain the unusual features of the data and that, as a by product, predicts abundant cosmological antimatter, in particular almost at hand, in the Galaxy. Though the model may be rather speculative, the observed objects present serious challenge to the theory and possibly indicate that “there is something rotten in the state of the universe”.

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LNF Mini-Workshop Series: Collective Effects in Storage Rings. In honour of Theo Demma

This mini-workshop is devoted to collective effects and electron cloud studies in circular accelerators. The investigation and comprehension of collective effects is fundamental for the success of accelerators. In particular the electron cloud instability poses severe limitations to the performances of colliders or damping rings for linear colliders. These topics were deeply studied with great competence and passion by our colleague Theo Demma, who passed away a year ago. Theo was a special person and a friend for many of us and we dedicate this afternoon to his memory.

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Beyond Einstein’s Gravity: Dark Energy and Dark Matter as Curvature Effects

Extended Gravity Theories have recently attracted a lot of interest as alternative candidates to explain the observed cosmic acceleration, the flatness of the rotation curves of spiral galaxies, the gravitational potential of galaxy clusters, and other relevant astrophysical phenomena. Very likely, what we call “dark matter” and “dark energy” are nothing else but signals of the breakdown of General Relativity at large scales and could be interpreted as a sort of “curvature effect”. Furthermore, PPN-parameters deduced from Solar System experiments and strong field astrophysical phenomena (compact objects, magnetars and neutron stars) do not exclude the possibility that such theories could give other observable effects. We review these results giving the basic ingredients of such an approach.

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Bruno Touschek Memorial Lectures 2015

The Bruno Touschek Memorial Lectures (BTML) were established in 1987 to honor the life and works of Bruno Touschek (see FPS, Vol.33). The Lectures have been continued in the last few years with distinguished scientists lecturing on important innovative research topics and historical perspectives. This year the Lectures will be dedicated to Cosmology and Dark Matter with Joseph Silk talking about: "Where next for  the Cosmic Microwave Background: to B or not to B"; and Gianfranco Bertone talking about: "Identifying Dark Matter with Astroparticle Experiments and the LHC". The event will be held on December 10th 2015, in Aula Bruno Touschek starting at 10:00. In the afternoon, Professor Roberto Battiston, President of the Italian Space Agency, will give a colloquium on Space Science, addressed to the general public

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Dark Portals: from simplified models to motivated theoretical embeddings

The main Features of the phenomenology of WIMP dark matter candidates, as well a broad range of related processes testable at collider, can be described by simple Extension of the Standard Model by a DM candidate and a mediator of its interactions. I will show, mainly focusing on the case of fermionic DM with spin 1 mediator, how combining constraints from different dark matter search strategies can provide hints on the structure of These theories. I will also discuss possible theoretical embeddings of These simplified Setups and how current constraints and future Signals can be used to discriminate different theoretical Frameworks.

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