Inter-University Attraction Pole meeting

Thursday 22 Jan 2009, 09:00 → 18:25 Europe/Brussels

auditoire Montesquieu: MONT01 (Louvain University)

This January 2009 session of our regular meeting will consist on review talks in the morning while the afternoon makes room for shorter talks, preferably by newcomers. Due to the high number of attendants of the previous meetings, you are kindly invited to register to participate to the event. If you would like to give a talk, please mention it in the registration form, as well as title and abstract. The timetable will be published in due time. Please check this website for more information or contact us by email at: cp3-iuap-meeting@uclouvain.be

09:00 Welcome

1 IAP news

Speaker: Prof. Jean-Marie Frère (ULB-PhysTh)

document jean-marie_frere.pdf

Morning session: review talks

2 Future experiments working group summary

Speaker: Prof. Nick Van Remortel (UA)

document ASPERA_Era-Net.ppt nick_vanremortel.pdf

3 The CMS cosmic experience, and plans for 2009

After the deception following the LHC incident on September 19th, the CMS collaboration went through an important challenge by collecting cosmic data for four weeks. Nearly 300 millions cosmic events were collected using the full detector at the nominal magnetic field of 3.8T. Lessons and results from that exercise will be presented together with preliminary plans for 2009.

Speaker: Dr Christophe Delaere (UCL)

document christophe_delaere.pdf

11:15 Coffee break

4 Aspects of supersymmetry breaking

I will review the basic elements of explicit and spontaneous supersymmetry breaking. I will explain F-term and D-term supersymmetry breaking with pedagological examples. I will discuss possible applications in model building and related problems, revisiting the gauge mediation scenario. Finally, I will introduce mechanisms of dynamical supersymmetry breaking.

Speaker: Dr Alberto Marriotti (VUB)

document alberto_mariotti.pdf

12:30 Lunch break + IAP board lunch meeting

Afternoon session: contributed talks

5 Relating dark matter and neutrino masses in supergravity

We study the supergravity phenomenology in the case of an alternative seesaw mechanism for generating neutrino masses. Changes in the neutrino sector lead to a modification of the supersymmetric particle spectrum and the sneutrino arises naturally as the lightest supersymmetric particle. The obtained sneutrino has a relic density within the WMAP range and is compatible with present nuclear recoil bounds.

Speaker: Dr Chiara Arina (ULB-PhysTh)

document 1_chiara_arina.pdf

6 Successful Leptogenesis in SO(10) Unification with a Left-Right Symmetric Seesaw Mechanism

We study thermal leptogenesis in a broad class of supersymmetric SO(10) models with a left-right symmetric seesaw mechanism. We show that including lepton flavour effects together with the second-lightest right-handed neutrino, leptogenesis can work for specific spectra reconstructed from the low-energy data. Moreover, we show that corrections to the relation Me=Md are crucial ingredients for leptogenesis to work.

Speaker: Dr François-xavier Josse-Michaux (ULB-PhysTh)

document fxjm.pdf

7 Applications of the gauge/gravity duality

The old suggestive observation that black holes often resemble lumps of fluid has recently been taken beyond the level of an analogy to a precise duality, that relates holographically a sector of anti-de Sitter gravity to fluid dynamics. We will review this correspondence and some of its applications, with an emphasis on the study of instabilities of black strings and fluid tubes.

Speaker: Dr Marco Caldarelli (KUL)

document 3_caldarelli.pdf

8 ttbar production process as a background to standard ModelHiggs decay to WW*

I will briefly describe, first, the current status of the H->WW* analysis in CMS and discuss about its main news and messages. Concentration will be more on our group contribution in this analysis and the results obtained so far. In the second (and main) part of the talk, I will focus on the ttbar background as one of the main background processes of H->WW events. Therefore the approach for ttbar background measurement is described by introduncing a control region and optimizing selection cuts which enhance this background and then using extrapolation of errors the total uncertainty of this background in the Higgs signal region is estimated. At the end I will discuss about possible improvements and development of the analysis and then a final conclusion is made.

Speaker: Dr Majid Hashemi (UA)

9 Central Exclusive Dijet Production

In view of the recent diffractive dijet data from CDF RunII, we critically re-evaluate the standard approach to the production of high-mass systems in proton/antiproton collision. A central exclusive dijet production is characterized by a large separation in rapidity of the final products and by few hadronic remnants. This mode of production is interesting because, from the measurement of the momenta of the daughter proton and antiproton, it is possible to reconstruct the mass of the centrally produced system without detecting it. Typical calculations of central exclusive production are divided in five pieces, the lower order QCD calculation and four corrections that can be large and leads to large uncertainties on the value of the cross section. All the arguments developed here can be used in order to improve our understanding of Higgs boson exclusive production.

Speaker: Ms Alice Dechambre (ULg)

document alice_dechambre.pdf

16:00 Coffee break

Ending session: invited talk

10 Implications of the PAMELA and ATIC excesses

Taking into account spins, we classify all two-body non-relativistic Dark Matter annihilation channels to the allowed polarization states of Standard Model particles, computing the energy spectra of the stable final-state particles relevant for indirect DM detection. We study the DM masses, annihilation channels and cross sections that can reproduce the PAMELA preliminary indications of an e+ excess consistently with the PAMELA p-bar data and the ATIC/PPB-BETS e++e- data. From the PAMELA data alone, two solutions emerge: (i) either the DM particles that annihilate into W,Z,h must be heavier than about 10 TeV or (ii) the DM must annihilate only into leptons. Thus in both cases a DM particle compatible with the PAMELA excess seems to have quite unexpected properties. The solution (ii) implies a peak in the e++e- energy spectrum, which, indeed, seems to appear in the ATIC/PPB-BETS data around 700 GeV. If upcoming data from ATIC-4 and GLAST confirm this feature, this would point to a O(1) TeV DM annihilating only into leptons. Otherwise the solution (i) would be favored. We comment on the implications of these results for DM models, direct DM detection and colliders as well as on the possibility of an astrophysical origin of the excess.

Speaker: Prof. Alessandro Strumia (Pisa U.)

document PAMELA_strumia.pdf