MFT: Motivations and Expectations

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1 Physics Week NFN NF Frascati 18 pril 2012 ntonio Uras for the MFT Working Group yon PN

2 Outline Physics Motivations ow mass and low pt dimuon reach: a unique feature at the H ow pt reach for open Heavy Flavors and Quarkonia MFT Performances: latest results Signal and background in the low mass region Open questions 2/20 ntonio Uras

3 Physics Motivations

4 ow Mass Dileptons from the QGP Properties of hadrons well known in free space (e.g. hadron production in e+e annihilations) Hadron spectral functions modified in the hot nuclear matter due to the restoration of the chiral symmetry: opportunity to test our understanding of strong interaction and deconfinement Best probes: resonances with a lifetime than the lifetime of the deconfined medium Best decaying channel: dileptons, escaping from the surrounding medium with negligible final state interaction ight Vector Mesons 4/20 ntonio Uras ρ(770), 1.3 fm/c ω(782), 23.4 fm/c φ(1020), 44.8 fm/c

5 ow Mass Dileptons from the QGP ρ(770): 1.3 fm/c lifetime, several generations decay to the dilepton channel at different stages of the collision process. ts spectral function contains integrated information on the space-time evolution of the medium Basic tool: comparison between mass spectra from elementary and nuclear collisions. Spectral function modification appears as an excess w.r.t. the expectations from elementary collisions 5/20 SPS: excess observed and studied by RS/N45 (dielectrons) and N60 (dimuons) RH: excess observed by PHNX and STR (dielectrons) with some inconsistencies between the two experiments H: still no results... ntonio Uras

6 ow Mass Dileptons from the QGP: SPS (~20 GeV) ρ broadening scenario accounts for the observed excess under 1 GeV/c2 in nucleus-nucleus w.r.t. elementary collisions N60: precise characterization of the excess even above 1 GeV/c2, different interpretations currently discussed controversially 6/20 ntonio Uras

7 ow Mass Dileptons from the QGP: RH (~200 GeV) PHNX excess at low masses: e l z z u ncreasing rapidly with centrality X p N H P oncentrated at low pt (pt < 1 GeV/c) annot be reconciled within any of the theoretical models proposed STR preliminary data: compatible with the same models explaining SPS data Parton-Hadron-String-Dynamics transport approach (innyk, assing, Bratkovskaya et al, November 2011) 7/20 ntonio Uras

8 ow Mass Dileptons from the QGP: H (~2000 GeV) is the only experiment designed to have a low p T reach from p-p to Pb-Pb collisions ow mass dileptons in the electron and muon channels (complementary rapidity ranges) Results already available from the muon channel Proton-proton collisions: excellent agreement within data and expected sources. Strong basis for Pb-Pb observations Pb-Pb collisions: under study, signal/background level is the main limitation. (See presentation by. asula) ow mass dilepton measurement in Heavy-on is a challenging task. f the H wants to stay in the game, must improve its capabilities both in the electron and muon channel 8/20 ntonio Uras

9 MFT Physics: Heavy Quarks mportance of extending muon and electron measurements down to low pt: exclusive range at the H from p-p to Pb-Pb Understanding of the non-perturbative component of the production mechanisms, expected to be concentrated at low p T Open charm down to low pt provide a more reliable reference for the quarkonia production R down to zero pt for quarkonia to test production mechamisms 9/20 ntonio Uras

10 MFT Physics: Heavy Quarks The MFT would open new perspectives for the muon channel: Model-independent disentanglement of open charm and open beauty production, on the basis of the offset distributions Reduction of the background coming from weak decays of pions and kaons and improvement of mass resolution for J/ψ and ψ' Disentanglement of prompt and displaced J/ψ production mprovement of the S/B ratio + higher integrated luminosities: Detailed study of R down to zero pt for J/ψ and ψ': essential to test regeneration mechanisms, expected to be effective at low pt Detailed study of the v2 parameter for the J/ψ: pt dependence of elliptic flow may help to disentangle direct production or charm quark coalescence for the J/ψ ow pt Quarkonia and Open HF measurements in Heavy-on at the H may be the only way to clarify open questions on production mechanisms. High quality measurements need improvement of capabilities both in the electron and muon channel 10/20 ntonio Uras

11 Physics Performances: ow Mass ll-pt trigger match required for all the tracks

12 urrent Simulation Scenarios MFT setup: 5 planes, μm2 Pile-up scenario for a 25 μs readout time: 1 Pb-Pb central collision + 1 PbPb central collision (with different prim. Vertex) Signal: parametric generation of ω and φ mesons 12/20 ntonio Uras

13 Selection uts Sources of backgrounds: muons from pions/kaons (and muons from D, B mesons) 13/20 ω, all match φ, all match ω, good match φ, good match ntonio Uras π/k, all match Tentative cut region

14 Rejection Power: Single Muons Rejection power after the cut on the χ2-offset plane: single muons μ from ω μ from φ μ from π/k Same rejection power for the muons of ω and φ Strong pt dependence for the muons of ω and φ Strong(er) rejection power for the muons from pions/kaons Negligible pt dependence for the muons from pions/kaons 14/20 ntonio Uras

15 Fraction of Dimuons Surviving the ut ω φ Strong dependence on pt and rapidity (as expected) Same rejection for ω and φ dimuons 15/20 ntonio Uras

16 Matching fficiency: Single Muons from ω Matching efficiency before and after the cut on the χ2 offset plane: ω mesons Without cut With cut 16/20 ntonio Uras Without cut With cut

17 Matching fficiency: Single Muons from φ Matching efficiency before and after the cut on the χ2 offset plane: φ mesons Without cut With cut 17/20 ntonio Uras Without cut With cut

18 Mass Resolution: ω mesons Mass fit with MFT: rystal Ball (signal) + Gaussian (fakes) 46 MeV/c2 14 MeV/c2 12 MeV/c2 12 MeV/c2 Statistics limited below 1 GeV/c 14 MeV/c2 18/20 ntonio Uras

19 Mass Resolution: φ mesons Mass fit with MFT: rystal Ball (signal) + Gaussian (fakes) 49 MeV/c2 19 MeV/c2 15 MeV/c2 17 MeV/c2 Statistics limited below 1 GeV/c 21 MeV/c2 19/20 ntonio Uras

20 onclusions and Outlook mproving capabilities in low mass and low pt physics both in the electron and muon channels is of interest for the whole H Heavy-on program. MFT may play a major and crucial role ow mass dimuons as well as J/ψ and ψ' dimuon measurements at low pt represent a unique feature at the H MFT will allow to improve the S/B by means of better mass resolutions and background rejection Simulations status and open issues: Optimization of the rejection efficiency for the background muons (especially at low p T) valuate the expected S/B as a function of p T for the mass region from the threshold up to the charmonia states Realistic evaluation of the expected misalignment Optimization of the MFT setup: pixel size, planes' thickness 20/20 ntonio Uras

21 Backup Slides

22 ow Mass Dileptons from the QGP: RH (~200 GeV) PHNX Proton-proton measurements well described by the cocktail of expected sources, both for PHNX and STR 22/20 ntonio Uras

23 ow Mass Dileptons from the QGP: RH (~200 GeV) ρ not included yet!! PHNX u-u minimum bias measurements: strong excess at low masses for PHNX after all expected sources are included 23/20 ntonio Uras

24 MFT Physics: Heavy Quarks Heavy Quarks: short and long time scales of collision dynamics Short formation time thanks to the large quark masses: information on the initial stage of the collisions ong lifetime of charm and beauty hadrons, probing the evolution of the deconfined medium Probe the deconfined medium through the sharp signal of narrow quarkonia states 24/20 ntonio Uras

25 Simulation Strategy Beam Pipe Realistic scenario for the future beam pipe worked out in collaboration with the technical coordination and the H vacuum group V0 and T0 not shown for clarity From simulations: YNDR beam pipe design offers by far the best compromise between physics performances and R&D + costs 25/20 ntonio Uras

26 MFT: Global Tracking Strategy 1) The MUON track is extrapolated back to the origin 2) The extrapolation is evaluated at the last plane of the telescope (the one closest to the absorber) 3) For each cluster in the plane, its compatibility with the parameters of the extrapolated track is checked, in terms of the quantity: x Â2clust y ¾x x2 ¾y2 + y 2 ¾x2 2 x y cov(x; y) = ¾x2 ¾y2 cov2 (x; y) ¾y MFT plane 26/20 ntonio Uras Distance between the cluster and the track at the plane along X and Y ovariance matrix elements of the track parameters after extrapolation (+ cluster size along X and Y) MFT: Status of the o

27 hapter 2: Simulation Strategy MFT Planes MFT planes structure fully described in liroot. Disk-shaped support with front and back assemblies of sensible and readout volumes urrent simulations: 20 μm pixels and x/x0 = 0.3% for a single plane FRONT BK 27/20 ntonio Uras MFT: Status of the o

28 hapter 2: High Multiplicity Secondary Production (z, R) scatter plot for the origin of particles (primaries and secondaries) Secondaries more copiously produced within the cylinder than the cone Has this difference a relevant impact on the planes' occupancy? 28/20 ntonio Uras MFT: Status of the o

29 hapter 2: High Multiplicity Planes' Occupancy Occupancy differences between conical and cylindrical beam pipe are visible, but hardly significant if compared with the overall multiplicity 29/20 ntonio Uras MFT: Status of the o