Flavor anomalies in B physics

• Javier Virto (Bern)

Room: High Energy Building, Seminar Room In the last few years, several interesting anomalies have been observed in B meson decays. First, some branching fractions and angular distributions in b --> s mu mu seem to disagree with current Standard Model predictions. Second, LHCb has reported a measurement of an observable sensitive to lepton-flavor non-universality which is different from zero at the 2.6 sigma level. This observable is a b-->s transition and the deviation is consistent with the anomalies in b --> s mu mu; thus this is very persuasive. Third, there is another hint of lepton-flavor non-universality in charged b --> c semileptonic exclusive transitions, which might be related to the one in b --> s. I will review these B-physics anomalies, paying attention to the theoretical uncertainties in the SM predictions, and to the new physics implications.

Who ordered that? Investigations of the top-Higgs connection

• Andrea Giammanco (Louvain, CP3)

Room: High Energy Building, Seminar Room The top quark is the heaviest known elementary particle, and it features a tantalizing numerical coincidence: from its measured mass, the Standard Model predicts a value of its Yukawa coupling to the Higgs boson strikingly close to 1. This stimulated a flourishing theoretical literature entertaining the possibility of a deep connection between the top quark and the actual mechanism of Electro-Weak Symmetry Breaking. This talk reviews the state of the art and the future prospects for the following, complementary, experimental efforts at the LHC: precisely measuring the top quark mass; constraining the modulus of the Higgs-top Yukawa coupling via the search for the ttH process; and constraining the phase of this coupling (relative to the Higgs coupling to W bosons) by exploiting a subtle interference effect.

Anomalous e+e- production in 8Be

• Matyas Hunyadi (MTA Atomik, Debrecen)

Room: High Energy Building, Seminar Room Predictions on the identity of the gauge boson of light dark matter suggest vector bosons in the mass range of 10 MeV - 10 GeV. Several attempts were made to find such particles by using data from running facilities. Since no evidence was found, limits were set on their mass and their coupling strength to ordinary matter. Researchers thus turn their attention to search for less massive candidates in the MeV scale and with a short life time, which decay mostly into electron-positron (e+-e-) pairs. In our recent work, we searched for such e+-e- pairs in nuclear transitions. We measured their angular correlation in internal pair creation for the M1 transition depopulating the 18.15 MeV state in 8Be. A significant, peak-like deviation was observed with respect to the predicted angular correlation for the internal pair creation. To our best knowledge, present nuclear physics theories cannot account for such deviation, however, assuming the creation and subsequent decay of a Jπ=1+ particle with a mass m0c2 = 16.70(61) MeV gives a satisfactory fit to our observations.

Short baseline neutrino anomalies

• Carlo Giunti (TO)

Room: High Energy Building, Seminar Room I review the experimental indications in favor of short-baseline neutrino oscillations. I discuss their interpretation in the framework of neutrino mixing schemes with one or more sterile neutrinos which have masses around the eV scale. I present arguments in favor of effective 3+1 neutrino mixing with one sterile neutrino at the eV scale. I discuss the implications for future neutrino oscillations experiments and for the experiments sensitive to the absolute values of neutrino masses (beta decay, neutrinoless double-beta decay and cosmology).

Reactor antineutrinos: anomalies interpretations, and new experiments

• Manfred Lindner (MAX-PLANCK-INSTITUT)

Room: High Energy Building, Seminar Room Reactor anti-neutrinos have contributed important insights into neutrino properties. Precision measurements led, however, also to certain discrepancies between simulated neutrino spectra an measurements. The talk will cover aspects of the so-called bump and the flux anomaly, possible explanations and prospects for experimental tests. The talk will in addition cover the potential of certain new reactor experiments.

The proton charge radius conundrum

• Krzysztof Pachucki (Warsaw)

Room: High Energy Building, Seminar Room The 2010 measurement of the muonic hydrogen Lamb shift by Pohl and collaborators has questioned our understanding of hydrogenic systems. A significant disagreement with theoretical predictions, which can be interpreted as a discrepancy in the proton charge radius between electronic and muonic measurements has not been resolved till now. A single muonic measurement stands against dozens of electronic hydrogen and electron- proton scattering ones and no simple extension of the Standard Model can fix this. We will argue that the only solution which does not violate the lepton universality is the underestimated uncertainty of all the electronic measurements and it is the muonic hydrogen value which is the correct one. As a consequence this hypothesis will cause a significant changes in fundamental physical constants and I will present all possible means of verifying the new proton charge radius value.

Muon g-2: theoretical interpretations

• Massimo Passera (PD)

Room: High Energy Building, Seminar Room I will present recent developments in the Standard Model prediction of the muon g-2 and the long-standing discrepancy with its measured value

Muon g-2 experiments

• Alberto Lusiani (Scuola Normale Superiore and INFN, Pisa)

Room: High Energy Building, Seminar Room We review the status and the prospects of the experimental measurement of the muon magnetic moment anomaly, a_mu = (g_mu-2)/2. The most precise measurement has been done by the BNL E821 experiment and has an uncertainty of 0.54 ppm. The Muon g-2 Fermilab experiment is approaching data-taking and has the goal to reduce the uncertainty by a factor 4. As second experimental effort is on-going at J-PARC with the aim to measure a_mu with an uncertainty of abour the same size of the BNL experiment in a first stage, with a subsequent upgrade to reduce the uncertainty at the same level as the Fermilab experiment.