ALICE and LHCb in the HL-LHC era

Transcription

1 ALICE and LHCb in the HL-LHC era LHC CHAMONIX 2011 January 27, 2011 Sergio Bertolucci CERN

2 General considerations In the last couple of years, the LHC original experimental programme is undergoing the filter of reality. Drivers of the reassessment are: LHC luminosity evolution LHC operation modes Operation/maintenance scenarios Upgrades (machine and experiments) Resources etc 2

3 General considerations(2) A number of issues of consistency/compatibility, which could not be addressed in sufficient details at the time(s) of approval, are resurfacing now and are keeping our LPC/LMC meetings lively. Just to quote a few: Running 4 IP s with widely different running conditions p- A runs (approved and forgotten for a long time) TOTEM Long term upgrade scenarios 3

4 Long Term (HL-LHC) LHC) So far all the upgrade schemes have been studied assuming only two general purpose detectors, ATLAS and CMS, operating. Taking into account the changed scenario: Will ALICE and LHCb run in HL-LHC time? When and what process to decide it? What are the beam parameters they want to exploit and the hardware changes they need in case of an upgrade? Not a trivial bunch of questions, considering the implications on the machine upgrade, on its ultimate performances, not to talk about the costs 4

5 How and when to decide it Global Physics output will be the main driver (assessment through the Scientific Committees, in primis by LHCC, with a robust participation of the accelerator experts). To be weighted with the implications on the LHC ultimate performances As early as possible, to secure resources/commitments from the funding agencies 5

6 ALICE Future

7 7 The 10 year LHC technical Plan

8 ALICE Program Baseline Program: initial Pb-Pb run in 2010 (< 1/20 th design L, i.e. ~ 3 x ) 2-3 Pb-Pb runs (medium -> design Lum. L ~ 10 27, 2.75 TeV -> 5.5 TeV ) integrate at least ~ 1nb -1 at the higher energy, and as close as possible to 1nb -1 at the lower one 1-2 p A runs (measure cold nuclear matter effects, e.g. shadowing) 1-2 low mass ion run (energy density & volume dependence) typ. ArAr continuous running with pp (comp. data, genuine pp physics) -> Baseline Program more than fills the 8 HI runs to ~ 2019 Following or included: lower energies (energy dependence, thresholds, RHIC) additional AA & pa combinations NEXT (after long shutdown at the end of the decade): details of program and priorities to be decided based on results, but Increase int. Luminosity by an order of magnitude (to ~ 10nb -1 ) - Address rare probes (statistics limited: for example, with 1nb -1 :J/Y: excellent, Y : marginal, Y: ok (14000), Y : low (4000), Y : very low (2000))

9 Jet and high-p t physics Energy of hard partons in a dense matter is reduced by gluon radiation collision energy losses (called jet quenching ) The main issue is to find where this energy goes radiated (small-p t?) gluons recoiled partons Needs excellent tracking at low momenta (p t <2GeV)! Jet quenching has specific dependence on parton colour charge (gluons vs. quarks) parton mass (i.e. velocity; heavy vs. light quarks) To distinguish: needs impact parameter resolution at low p t and particle identification!

10 ALICE 2011

11 ALICE Upgrades (ongoing) A program to upgrade some elements of ALICE is already ongoing In fact ALICE has evolved considerably from its Technical Proposal, largely because of the new data from RHIC, which are also at the base of some of the future upgrade ideas. In particular the TRD has been approved much later than the other central detectors 7/18 installed 3 more in winter 2010/2011 complete by 2012 a new EMCAL calorimeter (very important for jet-quenching) has been added recently US project, with French and Italian involvement. 4 SM installed in 2009 out of 11 Complete in winter shutdown 2010/2011 Further 6 SM on opposite side in phi (DCAL) approved DCAL Complete by 2012, installed in 2013

12 3/5 PHOS 18/18 TRD 18/18 TOF 7/7 HMPID 10/10 EMCAL 2x 2x ALICE x 2x 2x

13 Upgrades (future) Upgrade for >= Objectives: Extend the Physics reach (independent on L ) Improve the rate capability (in view of higher AA L ) High rate upgrade: increase rate capability of TPC (faster gas, increased R/O speed) rare hard probes (Υ, g-jet, ) DAQ, TRIGGER & HLT upgrades: more bandwidth, more sophisticated and selective triggers Particle ID upgrade: extend to p T range for track-by-track identification to O(20) GeV/c new physics interest, based on RHIC results Forward upgrades: new detectors for forward physics (tracking & calorimetry) low-x in pa, AA Extend ALICE coverage for diffractive Physics Inner Tracking upgrade: 2 nd generation vertex detector (closer to beams, extended acceptance, capabilities) heavy flavour baryons, fully reconstructed B,

14 LHCb: the long-term future A reminder: Physics programme of LHCb approved for 10 years of data taking at s = 14 TeV, with 2 fb -1 /y (and a m.4) As proven with 2010 data, LHCb is a fantastic generic forward detector particularly suited to study flavor physics at LHC: Excellent vertexing, tracking and PID Best mass resolution achieved for heavy flavors at LHC Flexible and highly efficient trigger LHCb is ready for discoveries, but limited in the amount of integrated luminosity (L), collected with m d 2.5 (the goal to collect ~5 fb -1 over coming ~5 years is pretty ambitious)

15 Strongest constraints on MSSM Higgs come not from direct searches but from B s mm, b sg and b tn By measuring BR(B s mm) LHCb will probe the entire best-fit region of parameters with 2011 data. Direct searches would require several years running at nominal L to achieve this goal

16 LHCb in the long-term future How much L is needed to characterize NP? Many physics goals motivate for 50 fb -1 An upgrade is proposed to increase data sample by a factor of 10 with a fully software based trigger, giving flexibility to respond to physics interests: Run at L= 10 33, no particular need to change IP configuration

17 LHCb key measurements to search for NP CPV phase, f s in B s mixing (B s J/yf & B s ff) - 5 fb -1 : Look for significant enhancement, to test CKM paradigm in B s system - 50 fb -1 : Make true precision measurement, a la B-factories determination of b B s mm (In SM BR= ) - 5 fb -1 : Look for significant NP enhancement; (almost) attain 5 s sensitivity at SM BR - 50 fb -1 : Precision measurement of BR to <10% and see B d mm; Ratio B s mm / B d mm excellent test of MFV models B d K*mm, K*ee & B s fg are sensitive to helicity structure of NP couplings - 5 fb -1 : First measurement of AFB with good precision - 50 fb -1 : Measurement of photon polarization and other useful variables to discriminate between various NP models using full angular analysis. Precise theoretical predictions under control! Tree level determination of UT angle gamma - 5 fb -1 : First good measurement (~4 ) necessary for precise CKM metrology - 50 fb -1 : Measure to 1 or better to keep up with progress in lattice QCD Study of CP violation and rare decays of charm (e.g. D mm) Precision study with O(10 fb -1 ) will reach theoretical accuracy for many observables

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19 First phase (~5 fb -1 ): Find or rule out large deviations from SM Upgrade (~50 fb -1 ): Study NP couplings

20 In addition to the approved programme of b (and c) heavy flavour physics, LHCb is adaptable to other physics studies, with its unique coverage of the forward region Lepton Flavour physics: Search for Majorana neutrino Search for Lepton Flavour violation in t decays Physics beyond Flavour: (with large data samples in forward direction) Exotics (in particular hidden sector ) Electro-Weak physics Central Exclusive Production (CEP)

21 Lepton Flavour physics -Search for Majorana neutrinos in D and B decays directly: Look for long lived neutrinos. Interesting BR start at ~ 10-7 level. Since such neutrinos are very weakly interacting they cover large distance before decaying (a fraction of ~10-4 decay within 0.5 m) Well observable signature with 50 fb -1 and software trigger which provides excellent efficiency for long lifetime and distinctive topology indirectly: Look for resonant production of same-sign charged leptons in e.g. D s+ p - l + l + or B + K - l + l +. LEP constraints imply interesting BR at level < Again should be accessible with 50 fb -1 of data - Search for Lepton Flavour Violation in t-decays Current limits from B-factories: BR(t mg)< , BR(t mmm)< With data sample ~50 fb -1 LHCb should improve upper limits for neutrinoless t 3prong decays by an order of magnitude to reach a level of LFV predicted in models

22 Electro-Weak Physics Two of the most important quantities are sin 2 (q W ) and M W - sin 2 (q W ) can be extracted from A FB. In LHCb acceptance Z production occurs predominantly through collision of valence and sea quark, so axis of A FB measurement is well defined, and dilution low Preliminary studies indicate that LHCb can reach an accuracy of ~ on A FB with ~50 fb -1 of data 2.5 better accuracy on sin 2 (q W ) compared to current w.a.v. - Knowledge of PDF is very important to improve accuracy on A FB and M W. LHCb is complementary to GPDs and may provide vital input with high statistics data samples Acceptance of GPDs Experimental accuracy already approaching theor. uncertainties

23 Central Exclusive Production: pp p + X + p ( + stands for large rapidity gap) Very clean study of quantum numbers and nature of X Central exclusive onia production at LHCb Resolution on M(J/yg) good enough to distinguish relative contribution of c c0, c c1 and c c2 Exclusive J/y vertex Pile-up vertex MC c proportions: 52% : 36% : 12% Large data samples are needed for CEP studies: MC c proportions: 12% : 36% : 52% - QCD mechanism may provide vital input if CEP is used for Higgs and NP production - Study of c c and eventually c b production - Study of exotic particles, such as X(3872); Hunt for glueballs

24 In summary Once approved, experiments are very reluctant to be terminated.. usually for a number of good reasons, physics first. In the case of ALICE and LHCb, I think that both have good reason to think beyond 2020 also in consideration of the not overwhelming offer of new machines. I really hope (and I tend to believe) that new Physics will make the choice very easy! 24