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Codice concorso n. 2833
UNIVERSITÀ DEGLI STUDI DI MILANO
Procedura di selezione per la chiamata a professore di II fascia da ricoprire ai sensi dell’art. 18, comma 1, della Legge n. 240/2010 per il settore concorsuale 02/A1 Fisica delle interazioni fondamentali ,
(settore scientifico-disciplinare FIS/01- Fisica sperimentale) presso il Dipartimento di Fisica,
(avviso bando pubblicato sulla G.U. n. 65 del 22/08/2014 - Codice concorso 2833
Simone Gennai
CURRICULUM VITAE
INFORMAZIONIPERSONALI COGNOME GENNAI NOME SIMONE DATA DI NASCITA 05/02/1976ATTIVITÀDIRICERCAEPUBBLICAZIONISCIENTIFICHE
My scientific activity is entirely within the Compat Muon Solenoid (CMS) Collaboration. CMS is a general-purpose detector that is being built at the Large Hadron Collider (LHC) at CERN [7]. The principal goals of CMS are the search for the Higgs boson, and the investigation for New Physics signals. I have worked on both physics analysis (searches of the Higgs bosons in tautau final states and heavier beyond Standard Model resonances) and on the preparation of tools for the event reconstruction (tau identification and the particle-flow reconstruction). I gave substantial contributions to the implementation of a trigger to select hadronic-tau decays.
On the hardware side, I have worked on the preparation of the inner barrel silicon-strip tracker: from the test of the silicon sensors and equipped modules to the final barrel-layers construction.
I have lead the H->tautau analysis team for two years contributing to the discovery of the Higgs boson and to the first evidence of the Higgs boson couplings to leptons. In 2013 the CMS and ATLAS collaborations received the EPS HEPP prize for the Higgs boson discovery.
I am also a JHEP referee and I have been an internal INFN referee for selection of Italian research projects. The details of my work within the CMS collaboration are described in the following sections.
Trigger
The trigger in a hadron collider experiment is the first (and often the most important) step of the analysis. The CMS trigger system is composed by a first hardware stage (Level-1) and a
second software stage named High Level Trigger (HLT). The HLT is implemented as a sequence of reconstruction and selection steps of increasing complexity and refinement. The fully programmable nature of the processors in the Event Filter Farm enables the implementation almost offline like algorithms utilizing all the information in the event, reducing the Level-1 output rate of 100 kHz to few 100 Hz. I have been working on the design of the trigger devoted to select hadronic tau decays since the beginning of my Ph.D. fellowship, and since 2006 I am the coordinator of the tau trigger group. The first study in the HLT development appeared in the CMS Data Acquisition Project Technical Design Report, published in the Eur. Phys. J. C [3]. Since this first exercise much more detailed studies have been made; each time a more refined simulation of the apparatus and more similar conditions to the real data taking have been considering. I have presented results in few conferences. I have also contributed, even if with a minor effort, to a study on the possible use of the pixel detector in the Level 1 trigger. Since late 2008 the CMS Trigger group has developed the final version of the trigger menus for the initial startup of LHC. Special emphasis has been given to the reconstruction timing and the creation of the so-called Primary Datasets. I have supervised all the tau trigger activities, with a special interest in the analyses aimed to measure the tau trigger efficiency from data. I have also developed the first reconstruction sequences to use Particle Flow techniques in the jet and missing energy related triggers. In 2011 and 2012 I have been one of two Higgs trigger contact person and I have contributed to set up the triggers that collected the data used for the discovery of the Higgs boson. Since January 2013 I am one of two deputies of the trigger coordinator. My main duty is the coordination of the activities for the preparation to 2015 data taking which will most likely happen with 25 ns bunch spacing, an average number of pileup events of 40, with peak luminosity as high as 1034cm-2s-1.
With these conditions, it is mandatory to improve the 2012-like on line reconstruction to bring it as close as possible to the offline reconstruction (which has also evolved since 2012)
to improve the background rejection and be able to set trigger selections as close as possible to those used in the offline analyses to be able to efficiently select events at the trigger level with the 2015 running conditions without impacting the CMS physics programme.
In particular I have directly participated to the improvements in the track reconstruction with the aim of making it faster and improve the track quality and purity. The final goal is to have a faster (with respect to 2012) tracking sequence to be able to use particle flow techniques in a larger number of events and at the same time improving the jet and missing energy resolution to be able to tighten the thresholds without loosing the physics reach.
Off-line tau identification and particle-flow event reconstruction
The off-line identification of hadronic tau decays (tau jet) has been evolved in time, starting from a merely isolation procedure to the full use of the event description provided by the particle-flow reconstruction that delivers a unique list of reconstructed and identified particles. This is made possible by combining the information coming from different sub-detectors and making use of the redundancy of momentum and energy measurements. One of the most important improvements brought by the particle-flow reconstruction (together with a superior energy and direction resolution) is the possibility to select as leading particle
(i.e. the highest transverse momentum particle in the jet) either a charged hadron or a neutral pion, leading to an increase of signal efficiency of about 20%. The use of the particles populating the inner region of the tau jet can be used to further reduce the QCD jet contamination. Clearly the particle-flow technique brings improvements in any other reconstructed objects in CMS. As an example, the use of this technique, for jets and transverse missing energy (MET) reconstruction, have shown superior performances with respect to more traditional techniques. In 2006-2007 I was coordinating the offline tau reconstruction activities, and in 2008-2011 I was co-convener of the whole Particle Flow and TauID group. Apart from supervising all the activities devoted to improve the reconstruction and selections of tau jets in the simulation, I had to coordinate the work for the commissioning of the tau identification following the preparation of the needed workflow for the efficiency measurements. Several publications document my activity in this are,a before the data taking started, as the CMS Physics TDR Vol. 1 and as a Scientific Note on EPJ Direct [4,5] as well as conference proceedings. At the end of 2009 LHC collected the first physics data at a center of mass energy of 900 and 2400 GeV. These data have been used to commission the particle-flow event reconstruction, confirming the superior performances already shown in the simulated data, and a first measurement of the tau fake rate at 900 GeV. The study has also shown a very good agreement between data and simulation, never seen at the startup of a hadron-colliding machine. With the first data at 7 TeV the full Particle Flow reconstruction has been commissioned and now is used in basically all the CMS analysis. The results of the commissioning of the tau reconstruction and identification have been published in 2011 [10]. Since 2012 the particle-flow reconstruction became the standard algorithm not only for taus but also for jets and MET. The Jet and MET reconstruction performance has been documented in [12] and [13].
The list of reconstructed particles is now used also in the standard isolation sequence for electrons and muons. My main proposal for 2013 and 2014 is to improve the usage of particle-flow techniques in the online reconstruction.
Physics analyses
The tau identification allows to select, with high efficiency, events in several interesting final states both in the SM (Higgs boson decays) or in beyond Standard Model scenario as supersymmetric (SUSY) or extra dimension (ED) models. During the preparation of my master thesis I have studied two supersymmetric channels: A->Zh->ll bb and H->hh->bbbb. The former channel offers good opportunity for the discovery of the A Higgs boson of the SUSY model, in the mA range between 250 and 350 GeV/c2 for low values of
tan(β), while the analysis of the latter pointed out the need of a dedicated trigger selections for b-jets. I have been partially involved also in a b-physics study related to the b-quark production mechanism with the PYTHIA package. During my Ph.D. term I studied models with extra dimensions, such as the Randall-Sundrum one. This model postulates the existence of a scalar particle, the radion, that can mix with a Standard Model like Higgs boson. I have studied a possible decay of the radion (ϕ) into a pair of Higgs boson: ϕ-> hh-> tau tau bb-hh-> lepton+tau-jet+bb+X, which would allow the study of the two scalars at the same time. The analysis is sensitive to this ED scenario up to energy scale of 2 TeV, even considering possible sources of systematic uncertainties as realistic detector response and
uncertainties of the background estimation. My interests towards final states with taus led me to collaborate in analysis involving Higgs boson production. The first analysis I have joined was the MSSM Higgs boson decaying into taus in the fully hadronic final state (A/H->tautau->hadrons+X). The analysis is described in the CMS Physics Technical Design Report Vol. 2 [5]. The results have been published also in a separated paper discussing the CMS potentiality on the Higgs boson discovery and mass resolution [6].
Since the data taking started I have been involved in Standard Model and Exotica analyses, mostly in preparation of the search for the Higgs boson through its decays into tau leptons [11, 16].
I have been the analysis coordinator of high mass resonances decaying into taus and lately of the SM Higgs boson searches in taus. With the data collected in 2011 and 2012 the Higgs analysis team I was coordinated has managed to perform a multichannel search for a resonance decaying into tau pairs. This search has been interpreted both in terms of Standard Model Higgs boson and for its supersymmetic extensions [14,15]. This analysis has been combined with those looking for Higgs boson decays to b-quarks, photons and vector bosons. The full combination of these analyses led to the discovery of the new resonances with a mass of about 125 GeV [18, 19]. In addition, the latest version of the H->tautau analysis managed to show the first evidence of the Higgs boson couplings to leptons. The paper describing this very complex analysis made of 5 different final states (mu+tau, electron+tau, tau+tau, electron+electron and muon+muon) and several event-based categories has been published in JHEP [21]. I was not only supervising the whole analysis team as the co-coordinator of the effort, I was also directly involved in the development of the full hadronic final state channel (tau+tau). I have designed and configured the full hadronic trigger (made of two hadronically decaying taus and one extra jet) used to collect the data for this final state and I have designed the two main categories of the analysis (the boosted Higgs regime and the vector boson fusion one). The results of this analysis combined together with the H->bb channel have been submitted to Nature [22]. The results of the Higgs boson search into fermions have also been used in estimating limits to the couplings to fourth-generation fermions [20]. Serving as coordinator of Higgs searches analyses with tau final states I have also supervised the search for a light charged Higgs boson produced in top quark decays. The analysis managed to put stringent limits on the MSSM parameter space [17]. Newer limits have been achieved in a more recent publication [24].
I have also participated as internal CMS referee for other publications. In particular I have been in the review committee for the analysis of ZH->ll+invisible which set a limit on the branching ratio of the Higgs decays to invisible particles. The results of the combination of this analysis with another one aiming to the same limit setting have been published in [23]. I am currently the ARC chair for a NMSSM analysis looking for a Higgs boson decaying into two light scalars each of them decaying into tau pairs.
Hardware'
During my graduate studies I have participated to the test of the silicon sensors and modules of the Tracker Inner Barrel, both at the Pisa Laboratories and CERN facilities, to study the effect of the radiation damage of the silicon. The tests were functional to the construction
specifications, which would guarantee a fully working Tracker during all the running years of LHC. In fact, the silicon sensor performances can be heavily degraded by the huge flux of hadrons, photons and neutrons produced by the proton-proton, and secondary, interactions. Even if heavily irradiated, the charge collection efficiency would be 96% of the efficiency for non-irradiated detector, and hence a S/N ratio which will be larger than 12 even in the worst case. The data analysis has been published in the Nuclear Instruments and Methods [1]. During my PhD term I have worked on the problems related to the saturation of the read out chip of the silicon modules, due to large energy releases inside the silicon bulk. When a particle releases a high energy deposit inside a silicon sensor, the readout front-end electronics saturates. The saturation persists in time for few hundred nanoseconds, during which all the 128 channels of the APV are inefficient. This dead time of the chip can affect the track reconstruction performance of the CMS tracker. Simulation studies have shown that even considering a really pessimistic dead-time of 750 ns the total effect on the single muon track reconstruction is an efficiency loss of only 2%. The inefficiency of track reconstruction can cause a degradation of performances in the b jet identification, up to about 8% of efficiency loss. However with small modification of the reconstruction and the front-end electronics software it will be possible to full recovery the reconstruction and b-tagging efficiency. These simulations have been supported by test beam data and laboratories measurements. To better quantify the effect of these Highly Ionizing Particles (HIP), a dedicated test was performed in April 2002 at the Paul Scherrer Institute (PSI) with 300 MeV/c momentum pion beam. I have participated to the test beam preparation writing a program for the on-line monitoring, and in the analysis of the test beam data to extract the HIP event rate. Later, I have performed the measurements of the chip recovery time performed with a dedicated laser setup, allowing a better comprehension of this effect. The work has been published in Nuclear Instruments and Methods [2]. I have also contributed to the construction of the CMS inner Tracker at the INFN center in Pisa. The main commitments of the Pisa group are the integration and the test of the assembled part of the tracker. The integration consists on the assembly of the silicon sensor with the readout electronics, mechanical support and cooling pipes. In the same period I have joined the Data Quality Monitoring group, taking care of the algorithms used to compute the noise and the pedestals of the silicon tracker modules. The correct computation of the pedestals and noise is mandatory to have an efficient cluster reconstruction. The performance of the CMS tracker have been studied before and after the final installation, as an example through the analyses of collected cosmic events, and the outcome of this first stage of the commissioning have been published in [8,9].
During 2014 I have started again my involvement in the tracker hardware, working on the R&D for 3D pixel sensors for the CMS upgrade programme.
Computing
I have been involved in the production of the Monte Carlo events, during my Ph.D. term. I have been the contact person for the production operations in Italy for the whole 2005, and on author of the CMS Computing TDR.
1. Laura Borrello et al., “Comprehensive Study of the Effect of the Irradiation on Charge Collection Efficiency in Silicon Detector”, Nuclear Instruments and Methods in Physics Research Section A 461 (1-3) (2001) pp. 178-181.
2. W. Adam et al., ” The effect of highly ionising particles on the CMS silicon strip tracker”, Nuclear Instruments and Methods in Physics Research A 543 (2005) 463–482.
3. CMS Collaboration, “ The CMS high level trigger “, Eur. Phys. J. C 46, 605– 667 (2006) 4. CMS Collaboration, “Tau jet reconstruction and tagging with CMS”, Scientific Note
published in Eur. Phys. Journal C, Volume 46, Supplement 1, July 2006, pp. 1-21
5. CMS Collaboration, “CMS Physics Technical Design Report, Vol 2: Physiscs Performance”, J. Phys. G: Nucl. Part. Phys. 34 995-1579 2007
6. Gennai et al., “Search for heavy neutral MSSM Higgs bosons with CMS: Reach and Higgs-mass precision. Published in Eur.Phys.J.C52:383-395,2007 e-Print: arXiv:0704.0619 [hep-ph]
7. CMS Collaboration,”The CMS Experiment at the CERN LHC”, 2008 JINST 3 S08004 8. CMS Collaboration, “Performance studies of the CMS Strip Tracker before installation”,
JINST 4:P06009,2009
9. CMS Collaboration, “Commissioning of the CMS experiment and the cosmic run at four tesla” 2010 J. Inst.5 T03001 doi: 10.1088/1748-0221/5/03/T03001
10. CMS Collaboration, “Performance of the tau lepton reconstruction and identification in CMS”, 2012 J. Inst.7 P01001
11. CMS Collaboration, “Measurement of the inclusive Z cross section via decays to tau pairs in pp collisions at sqrt(S) = 7 TeV “, JHEP 08, 2011 doi: 10.1007/JHEP08(2011)117
12. CMS Collaboration, “Missing transverse energy performance of the CMS detector”, JINST 6 (2011) 09001
13. CMS Collaboration, “Determination of Jet Energy Calibration and Transverse Momentum Resolution in CMS”, J. Instrum. 6 (2011) P11002
14. CMS Collaboration, “Search for neutral Higgs bosons decaying to tau pairs in pp collisions at sqrt(S) = 7 TeV, Phys. Lett. B 713, 2012
15. CMS Collaboration, “Search for Neutral Minimal Supersymmetric Standard Model Higgs Bosons Decaying to Tau Pairs in pp Collisions at sqrt(S) =7 TeV”, Phys. Rev. Lett. 106 (2011 ) 231801
16. CMS Collaboration, “Search for high-mass resonances decaying into τ-lepton pairs in pp collisions atsqrt(S) =7 TeV”, Phys. Lett. B 716, 2012
17. CMS Collaboration, ”Search for a light charged Higgs boson in top quark decays in pp collisions at √s = 7 TeV”, JHEP 07 (2012) 143
18. CMS Collaboration, “Combined results of searches for the standard model Higgs boson in pp collisions at √s = 7 TeV”,Physics Letters B 710 (2012)
19. CMS Collaboration, “Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC”, Phys. Lett. B 716, 2012
20. CMS Collaboration, “Searches for Higgs bosons in pp collisions at √s = 7 and 8 TeV in the context of four-generation and fermiophobic models”, Physics Letters B 725 (2013)
21. CMS Collaboration,”Evidence for the 125 GeV Higgs boson decaying to a pair of τ leptons”, JHEP 1405 (2014)
22. CMS Collaboration, Evidence for the direct decay of the 125 GeV Higgs boson to fermions”, Nature Physics10, 557–560 (2014) doi:10.1038/nphys3005
23. CMS Collaboration,” Search for invisible decays of Higgs bosons in the vector boson fusion and associated ZH production modes”, Eur. Phys. J. C 74 (2014) 2980
24. CMS Collaboration, “Search for neutral MSSM Higgs bosons decaying to a pair of tau leptons in pp collisions”, arXiv:1408.3316 (Submitted to JHEP)
ATTIVITÀDIDIDATTICA,DIDIDATTICAINTEGRATIVAEDISERVIZIOAGLISTUDENTI
2013 Co-Supervisor of Valentina Arosio’s Master Thesis
(Title of the Thesis: Study of the Standard Model Higgs Boson in the fully hadronic di-τ decay channel in the CMS experiment at LHC)
2012 Co-Supervisor of Luca Mastrolorenzo’s Master Thesis
(Title of the Thesis: tau object charaterization in the CMS experiment at LHC and study of the H->tautau decay)
2009 Assistant for the course on the “Physics at Accelerators”, held by Prof. Vincenzo Cavasinni at University of Pisa.
2008-2009 Assistant for the second module of the course “Nuclear and SubNuclear Physics” (held by Prof. Flavio Costantini) at
Universita’ di Pisa.
2007 Introductory course on C++ as part of the course of “Laboratorio di Informatica per Fisici”, at Universita' degli studi di Milano-Bicocca.
2004-2006 Assistant for the course “Nuclear and SubNuclear Physics” at Universita’ di Pisa. The course was held by Prof. Carlo Bemporad.
2002-2004 Assistant for the course “Electromagnetism in vacuum and matter” at
Universita’ di Pisa. The course was held by Prof. Vincenzo Cavasinni and Prof. Giovanni Moruzzi.
ATTIVITÀISTITUZIONALI,ORGANIZZATIVEEDISERVIZIO
2013-present Deputy of the Trigger Coordinator in CMS
(Level 1 managerial position in the CMS organization) 2011-2012 Coordinator of the H->tautau analysis group in CMS (Level 3 managerial position in the CMS organization)
2011 Convener of the newly born Tau Id physics object group in CMS (Level 2 managerial position in the CMS organization)
2009-2010 Convener of the Particle Flow and Tau Id physics object group in CMS. (Level 2 managerial position in the CMS organization) 2009 (July) – 2010 Coordinator of Exotica searches with high pt taus in the final state 2009 Convener of the Beyound Standard Model Physics for the italian conference: Incontri sulla Fisica delle Alte Energie (IFAE)
2008-2011 Member of the Physics Coordination group in CMS 2006-2008 Coordinator of the Tau Trigger group in CMS and
Coordinator of the offline Tau identification group in CMS. (Level 3 managerial in the CMS organization)
2005 Contact person for the production operations in Italy. 2004-2005 Contact person for the tau identification in Italy.
ALTREINFORMAZIONI(STUDI E POSIZIONI LAVORATIVE)
Education
2004: Ph.D. with honors (70/70 cum laude) at Scuola Normale Superiore. Title of the thesis: Search of a graviscalar particle of the Randall Sundrum model with the CMS experiment at LHC, supervisor: Prof. Lorenzo Foa’.
2000: Degree with honors (110/110 cum laude) in Physics at Università degli studi di Pisa. Title of the thesis: Ricerca di bosoni di Higgs supersimmetrici con
l’apparato CMS nei canali:A->Zh->llbb e H->hh->bbbb, supervisor: Prof. Rino Castaldi.
1995: Diploma di maturità Scientifica (60/60) at Liceo Scientifico Barsanti e Matteucci, Viareggio.
Positions
2014 INFN founded CERN Associate (SimilFellow) 2013 Obtained ”Abilitazione per Professore Associato” 2011-present Permanent researcher at INFN Milano-Bicocca
2012-2013 Marie Curie at CERN (as cofounded third year fellowship) till 2013 February, 1st.
2010-2012 Fellowship at CERN (till February 1st, 2012)
2008-2010 Researcher (temporary term) at Scuola Normale Superiore. 2006-2008 Fermi’s Grant, at the Centro Studi Enrico Fermi in Rome. The
research program is: “Search of new Physics with the CMS detector”, Supervisor: Prof. Lorenzo Foa’.
2005 Passed the selections of the Istituto Nazionale di Fisica Nucleare for temporary positions (lately named R5 examination).
2004-2006 (Since July) 2-year Post-Doc position at the Scuola Normale
Superiore in Pisa. The research programme is titled: “Search for Extra Dimensions in CMS”. Supervisor: Prof. Lorenzo Foa’.
2004 Angelo Della Riccia fellowship (at CERN from January to June). 2001-2003 Ph.D. fellowship in Physiscs at Scuola Normale Superiore,
supervisor: Prof. Lorenzo Foa’
2000-2001 Post-laurea fellowship with Istituto Nazionale di Fisica Nucleare
Le dichiarazioni rese nel presente curriculum sono da ritenersi rilasciate ai sensi degli artt. 46 e 47 del DPR n. 445/2000.
Il presente curriculum, non contiene dati sensibili e dati giudiziari di cui all’art. 4, comma 1, lettere d) ed e) del D.Lgs. 30.6.2003 n. 196.
Il sottoscritto dichiara di essere consapevole che nel rispetto delle regole di trasparenza previste dalla Legge e come stabilito dal bando di concorso, i curricula di tutti candidati saranno pubblicati sul sito Web dell’Università degli Studi di Milano www.unimi.it/valcomp entro 30 giorni dalla scadenza del termine di presentazione delle domande.
Data 19/09/2014 Luogo Milano
