Introduction du degré de liberté de spin dans la fragmentation d'un quark. Application à la polarimétrie des quarks. (Main)

• Xavier Artru (IPNL, CNRS/IN2P3 et Université Lyon 1)

Room: Amphithéâtre Recherche Les modèles actuels de jets ne tiennent pas compte du degré de liberté de spin du quark. Or celui-ci produit des asymétries azimutales dans la fragmentation (effets Collins et jet-handedness), qui peuvent servir de "polarimètres à quarks". Après un bref rappel sur les effet Collins et jet-handedness, ainsi que sur les modèles de fragmentation sans spin, je présenterai un modèle récursif ultra-simplifié où l'information portée par le spin du quark est prise en compte à chaque étape. Ce modèle génère les asymétries Collins et et jet-handedness et peut s'incorporer dans les générateurs Monte-Carlos. De plus, même pour un quark non polarisé, il prédit un [pT carré] moyen plus grand pour les pions que pour les rhos. Un mécanisme alternatif basé sur les cordes est également capable des mêmes résultats.

Muon g-2

• Zhiqing Zhang

Room: Amphithéâtre Recherche

On the consistency between CP violation in the K vs. B_d systems within the Standard Model (Main)

• Diego Guadagnoli (LPT Orsay)

Room: Amphithéâtre Recherche In the K and B_d systems, indirect CP violation is quantified by the parameters epsilon_K and sin2beta respectively. Within the Standard Model, the uniqueness of the CP violating phase implies that the measurement of either between K and sin2beta permits to predict the other. Since both these parameters are very well measured, this turns into a powerful test of consistency. I discuss the status of this test, especially in the light of recent advances on the epsilon_K formula.

Rare K and B decays with non-standard missing energy (Main)

• Christopher Smith (IPN Lyon)

Room: Amphithéâtre Recherche The rare K and B semileptonic decays into neutrino pairs are well-known to be extremely sensitive to non-standard physics in the quark sector. In this talk, their capabilities to signal New Physics in the leptonic sector, or even to reveal entirely new invisible sectors, will be analyzed.

A possible connection between neutrino mass generation and the lightness of a NMSSM pseudoscalar (Main)

• Debottam Das (Laboratoire de Physique Theorique d'Orsay)

Room: Amphithéâtre Recherche One of the interesting properties of the NMSSM is that it can accommodate a light pseudoscalar of order 10 GeV. However, such scenarios are challenged by several experimental constraints, especially those related to the fermionic decays of the pseudoscalar. In this talk we propose a model where the NMSSM field content is extended by two gauge singlets, with lepton numbers $+1$ and $-1$. This serves the twin purpose of generating neutrino masses via the inverse see-saw mechanism and keeping the option of a very light pseudoscalar experimentally viable by opening dominant invisible decay channels of the pseudoscalar which help it evade the existing bounds.

Determining the photon polarization of the b->s gamma using the B->K1(1270) gamma->(K pi pi) gamma decay (Main)

• Andrey Tayduganov (LPT/LAL, Orsay, France)

Room: Amphithéâtre Recherche Recently the radiative $B$ decay to the strange axial-vector mesons, $B\to K_1(1270) \gamma$, has been observed with rather large branching ratio. This process is particularly interesting as the subsequent $K_1$ decay into its three body final state allows us to determine the polarization of the photon, which is mostly left- (right-)handed for $\overline{B} (B)$ in the SM while various new physics models predict additional right- (left-)handed components. A new method is proposed to determine the polarization, exploiting the full Dalitz plot distribution, which seems to reduce significantly the statistical errors. This polarization measurement requires however a detailed knowledge of the $K_1 \to K \pi \pi$ strong interaction decays, namely, the various partial wave amplitudes into the several possible quasi two-body channels, as well as their relative phases. The pattern of partial waves is especially complex for the $K_1(1270)$. We attempt to obtain the information through the combination of an experimental input and a theoretical one, provided by the $^3P_0$ quark-pair-creation model.

Two-Loop Corrections to Top-Antitop Production at Hadron Colliders (Main)

• Roberto Bonciani (LPSC)

Room: Amphithéâtre Recherche The status of the theoretical predictions for the top-anti top production in hadronic collisions is shortly reviewed, paying a particular attention to the analytic calculation of the two-loop QCD corrections to the parton-level matrix elements.

On jet dynamics in the quark-gluon plasma (Main)

• Yacine Mehtar-Tani (University of Santiago de Compostela)

Room: Amphithéâtre Recherche Jet physics in hadron collisions is known as one of the most accurate in testing perturbative QCD for 30 years. However, in Heavy-Ion collisions (HIC), at RHIC and at the LHC, the situation is much more involved due to the interaction of jets with the produced quark-gluon plasma right after the collision. Thus, a better theoretical control of jet dynamics in the presence of a QCD medium is becoming crucial if one would like to have a clean access to the properties of the QGP. To this end, we have investigated medium modification of the radiation pattern of a quark-antiquark antenna traversing a dense medium in order to learn how the QGP alters color coherence which is an important feature of the intRAjet structure in vacuum. In contrast to gluon radiation in vacuum, and unexpectedly, we find anti-angular ordering of gluon radiations and thus only the soft logarithmic divergence remains. These results provide a starting point for further and more complete studies on in-medium jet modification.

Present and future of lattice QCD (Main)

• Benoit Blossier (CNRS)

Room: Amphithéâtre Recherche We propose to report about some recent nice developments realized by the lattice community to bring a significant contribution to the effort made to reduce the theoretical uncertainty on hadronic quantities that could spoil the hope to detect effects of new physics in the flavor sector. Moreover those progresses allow new challenges: for instance studying physics of excited states to provide more information on the hadronic side of QCD sum rules, or extracting the basic quantities of resonant states and getting some hint about their decay to multi-hadron states, 2 topics that were believed to be numerically unrealistic 10 years ago.

Sigma term and strange content of the nucleon

• Alberto Ramos (Centre de Physique Theorique, Marseille (CNRS))

Room: Amphithéâtre Recherche The sigma term and strange content of the nucleon play an important role in hadronic physics and dark matter detection, yet they cannot be measured directly in experiment. I will present preliminary results of a fully controlled lattice QCD calculation of these quantities and discuss some of their implications.

Electromagnetic contribution to light hadron masses

• Antonin PORTELLI

Room: Amphithéâtre Recherche

Recent advances in neutrino (astro)physics (Main)

• Cristina VOLPE (IPN)

Room: Amphithéâtre Recherche A major step forward is occurring in our understanding of neutrino flavour conversion in media. This is due to the increase in the complexity of the modelling for neutrino propagation e.g. in supernovae, (inclusion of the neutrino-neutrino interaction, of shock waves and of turbulence). Compared to the case of our Sun, new flavour conversion phenomena have been shown to arise. In this talk I will first emphasize with an example that their underlying physical mechanisms can be very general. The complex flavour conversion phenomena are intertwined with key unknown neutrino properties, such as leptonic CP violation. I will summarize our recent findings on the search for indirect CP effects in supernovae and in Early Universe, at the BBN epoch.

Can physics before Quantum Mechanics lead to physics beyond the Standard Model? (Main)

• Gilbert Moultaka (LPTA-Montpellier, UMR5207-UM2/IN2P3/CNRS)

Room: Amphithéâtre Recherche We give a short account of an old and somewhat unjustifiably defamed approach to quantum phenomena, arguing though for its potential to provide a new kind of Higgsless physics beyond the Standard Model.

ATLAS SUSY searches: preliminary results and short term prospects (Main)

• Steve Muanza (CPPM)

Room: Amphithéâtre Recherche

Beyond the Standard Model in the TeV era

• Aldo Deandrea (IPNL)

Room: Amphithéâtre Recherche

Some cosmological implications of MiniBoone (Main)

• Pasquale Dario Serpico (LAPTh, Annecy-le-vieux)

Room: Amphithéâtre Recherche If interpreted as hint of new neutrino states and/or interactions, MiniBoone data might allow for a cosmological cross-check via helium abundance, CMB, and LSS data. I will review the main physical motivations behind the statement above, and discuss some forthcoming observational prospects. Likely, cosmological probes and to some extent direct mass measurements might offer a key test of most popular new physics scenarios invoked to explain the "anomalies".

The neutrino self-interaction: a magnetic resonance phenomenon? (Main)

• Sebastien Galais (IPNO)

Room: Amphithéâtre Recherche The study of neutrino-neutrino interaction is a very active field in neutrino astrophysics. Since a decade, physicists try to understand the flavor conversion of neutrinos, observed in numerical simulations, when they travel through the supernova (synchronization, bipolar oscillations, spectral split,...). In this presentation, I will first explain which interactions are relevant for neutrinos when they propagate through supernovae. Then I'll show the correspondence that exists between the neutrino self-interaction and the magnetic resonance phenomenon within two flavors. This calculation is the first to concretely show this analogy on the basis of a full numerical neutrino propagation.

Dark Matter phenomenology status (Main)

• Marco CIRELLI (SPhT - CEA/Saclay)

Room: Amphithéâtre Recherche

Dark matter searches with the Fermi-LAT (Main)

• Gabrijela Zaharijas (IPhT/CEA Sacalay)

Room: Amphithéâtre Recherche I will review the dark matter search strategies by the Fermi-LAT team, with a particular emphasis on the searches in the Galactic and extragalactic diffuse emission. The diffuse measurement contains a wealth of information due to a good angular resolution of the Fermi-LAT telescope and high statistics of events. I will discuss how this information can be used to look for particularities of a dark matter signal, and what are the difficulties involved in this task, both on experimental and model building side. Some expected improvements brought in by complementary experiments such as AMS-02, Planck and CTA will also be given.

Tribimaximal Mixing From Small Groups (Main)

• Akin Wingerter (LPSC)

Room: Amphithéâtre Recherche Current experimental data on the neutrino parameters is in good agreement with tribimaximal mixing and may indicate the presence of an underlying family symmetry. For 76 flavor groups, we perform a systematic scan for models: The particle content is that of the Standard Model plus up to three flavon fields, and the effective Lagrangian contains all terms of mass dimension <=6. We find that 44 groups can accommodate models that are consistent with experiment at 3 sigma, and 38 groups can have models that are tribimaximal. For one particular group, we look at correlations between the mixing angles and make a prediction for theta13 that will be testable in the near future. We present the details of a model with theta12=33.9, theta23=40.9, theta13=5.1 to show that the recent tentative hints of a non-zero theta13 can easily be accommodated. The smallest group for which we find tribimaximal mixing is T7. We argue that T7 and T13 are as suited to produce tribimaximal mixing as A4 and should therefore be considered on equal footing.

Metastable SUSY breaking without scales (Main)

• Felix Bruemmer (DESY)

Room: Amphithéâtre Recherche Modern models of metastable dynamical supersymmetry breaking often suffer from the presence of a small mass parameter, which needs to be tuned by hand to be smaller than the scale of SUSY breaking. In this talk some recent proposals to circumvent this problem are presented. One may generate the required mass scale from gauge singlets coupled to an auxiliary gauge group, or without singlets through a sequence of Seiberg dualities. Some of these models can be coupled to messenger fields in a very simple way, and can therefore be extended to realistic and natural models of gauge-mediated supersymmetry breaking.

Universal Extra Dimensions on the Real Projective Plane - Model and Phenomenology (Main)

• Luca Panizzi (IPNL)

Room: Amphithéâtre Recherche The Real Projective Plane is the unique 6 dimensional orbifold without fixed points in which chiral zero modes for fermions are allowed. Moreover, it contains a natural dark matter candidate, i.e. without imposing symmetries by hand. The main features of the model, such as its spectrum which is characteristic of the geometry of the orbifold, and some relevant phenomenological implications that could be tested at the LHC will be illustrated.

Light Colored Scalar as Messenger of Up-Quark Flavor Dynamics in Grand Unified Theories (Main)

• Nejc KOSNIK (LAL)

Room: Amphithéâtre Recherche The measured forward-backward asymmetry in the t tbar production at the Tevatron might be explained by the additional exchange of a colored weak singlet scalar. Such state appears in some of the grand unified theories and its interactions with the up-quarks are purely antisymmetric in flavor space. We systematically investigate the resulting impact on charm and top quark physics. The constraints on the relevant Yukawa couplings come from the experimentally measured observables related to D0--D0bar oscillations, as well as di-jet and single top production measurements at the Tevatron. After fully constraining the relevant Yukawa couplings, we predict possible signatures of this model in rare top quark decays. In a class of grand unified models we demonstrate how the obtained information enables to constrain the Yukawa couplings of the up-quarks at very high energy scale.

Baryon to meson transition distribution amplitudes and their spectral representation in terms of quadruple distributions (Main)

• Kirill Semenov-Tian-Shansky (CPHT Ecole Polytechnique, LPT Orsay)

Room: Amphithéâtre Recherche We consider the problem of construction of a spectral representation for nucleon to meson transition distribution amplitudes (TDAs), non-diagonal matrix elements of non local three quark light-cone operators between a nucleon and a meson states. We introduce the notion of quadruple distributions and generalize Radyshkin's factorized Ansatz for this issue. Modelling of baryon to meson TDAs in the complete domain of their definition opens the way to quantitative estimates of cross-sections for various hard exclusive reactions.

Cold nuclear matter effects on quarkonium production at RHIC and the LHC (Main)

• Nicolas Matagne (University of Mons)

Room: Amphithéâtre Recherche We study the Cold Nuclear Matter (CNM) effects on J/Psi and Upsilon production, whose understanding is fundamental to evaluate the Quark Gluon Plasma or Hot Nuclear Matter Effects. Two CNM effects are of particular importance: the modifications (here, shadowing) of the initial parton distributions (PDF) and the nuclear absorption the \bar{c}c (or \bar{b}b)-pair. Recent theoretical works have emphasized that the J/Psi production at low and mid-pT proceed via a 2 -> 2 process instead of a 2 -> 1 process, as assumed in the usual studies of CNM effects. When taking into account the exact kinematics of the 2 -> 2 process, visible differences appear in the obtained shadowing corrections, irrespective of which shadowing parametrization is used. This naturally induces changes in the absorption cross-section fit to the data, and hence to the deduced rapidity dependence. We will present our results in dA and AA collisions at RHIC and LHC energies, using several parametrizations of the nuclear PDF, and including the pT-dependence of CNM effects up to mid-values of pT, which are not accessible with the usual simplified kinematics. We extend our study to the upsilon case, where the first experimental results in dA at RHIC energy are available.

Le problème du fine-tuning revisité à la lumière du schéma de régularisation de Taylor-Lagrange (Main)

• Bruno Mutet (LPC Clermont-Ferrand)

Room: Amphithéâtre Recherche Nous ré-analysons les corrections radiatives à la masse du Higgs dans le cadre du modèle standard en utilisant le schéma de régularisation de Taylor-Lagrange. Ce schéma mène naturellement à des corrections complètement finies, dépendant d'un paramètre arbitraire. Cette formulation ne laisse apparaître aucune grande correction individuelle à la masse du Higgs. En d'autres termes, cette formulation indique que le problème du fine-tuning n'est qu'un artefact du schéma de régularisation et qu'il ne devrait mener à aucune interprétation physique. Une attention particulière est accordée aux différentes échelles d'énergie utiles à la description des corrections radiatives.

Modification of Coulomb law and energy levels of the hydrogen atom in a superstrong magnetic field (Main)

• Bruno Machet (CNRS)

Room: Amphithéâtre Recherche Superstrong magnetic fields modify the Coulomb potential of a proton and the energy spectrum of the hydrogen atom. After getting an analytical formula for this potential in the direction of the magnetic field, we obtain, analytically too, the spectrum on which the lowest Landau level splits. Therein, electrons are non-relativistic. For$B> 10^{13}T (=10^{17}G), we show that it is substantially modified by screening effects.

Evaluating twofold and threefold Mellin-Barnes integrals (Main)

• Samuel Friot (Universite Paris-Sud 11 - Institut de Physique Nucleaire d'Orsay)

Room: Amphithéâtre Recherche We present a method for obtaining the different multiple series representations of twofold and threefold master Mellin-Barnes integrals which appear in perturbative calculations. These series are, as a rule, analytic continuations of one another in different regions of convergence.