1 / 12

B s  D s K

B s  D s K. Steve Blusk, Liming Zhang, (& Sheldon, when he learns Gaudi, Python, RooFit…  ). Introduction. State of Affairs. g. SM?. l = sin q C  0.22; (A  0.8). |V ub /V cb | : Systematics limited, SM dominated |V td /V ts | : f B errors dominant, SM +NP

willa
Télécharger la présentation

B s  D s K

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Bs Ds K Steve Blusk, Liming Zhang, (& Sheldon, when he learns Gaudi, Python, RooFit…)

  2. Introduction State of Affairs g SM? l= sinqC0.22; (A0.8) • |Vub/Vcb| : Systematics limited, SM dominated • |Vtd/Vts| : fB errors dominant, SM+NP • sin(2b): Exp. error dominant (SM + NP) • Need : • Accurate measurement of g with TREES only • Precise measurement of g in LOOPS (SM+NP) • Precise measurement of a (SM + NP) • Reduce theory errors.. • If h≠0  CP Violation • Since Vcb real & base=1, arg(Vub) = g

  3. Interference between direct decay and mixing+decay(4 time-dep rates) Bs± DsK± Direct decay Phase relativeto Direct decay fs g+d Vts t Vtb s W W t Vtb* Vts* |l| ~ 1 sin term dominates Both O(l3), with different weak (& strong phases)

  4. Bs± DsK±, continued • It can be shown: • Dms =17.77±0.11 ps-1 (CDF) can be (re)measured in LHCb using BsDsp, • DGs and fs can be measured in BsJ/yf (presumably, a separate measurement). • SM: DGs ~ 0.07 ps-1, fs ~ -0.04 • This leaves us with four unknowns: l, g, d, A, which can be determined. • Expect l~1  sin term dominates • Time-dependence in these four decays can vary dramatically depending on d±g • Additional factor for mistag rate, (1-2wBs), in front of cos, sin terms not shown

  5. Sketch of dependence on d

  6. Previous work Bs  Ds K • Access to g also via B+DK+ • depends on time-integrated ratesonly. • Several modes/analyses could givesg~ 5-13o, depending on D decaystrong phases (2 fb-1) • Would be nice to push the errorhere down below 10o . • Currently, we only consider DsKKp • Other Ds modes could add (Liming) • BsDs* K? (comes for “free” in thetrigger, depending on mass window) • Broad low mass bump • Can we deal with it? From LHCb-2003-103, s(g+fs)~13o

  7. Likelihood Fit devleopments • Now using RooFit  very flexible for complicated PDF’s (still on learning curve) • Implemented 2 multi-dimensional PDFs • BsDsp: mass*time*(mix or unmix) – two 2D PDFs: • BsDsK: mass*time*flavor tag(Bs/Bs)*Ds-flavor(Ds+/Ds-) – Four 2D PDFs • Mass, time each have signal term & background terms • Acceptance, mass resolution and time resolution included • Fit variables in PDF: • Common to BsDsp and BsDsK: DGs, Dms, tBs, wBs, MBs, s(MBs), st_ • Sample-dependent: g, d, acceptance & background pars in mass & time,

  8. Reconstruction Effects (on BsDsK) Similar for Dsp ~ 10 fb-1 of data ~6200 / year total ~54% tag eff w = 0.33

  9. BsDsp, Fit to Mixed Events ~0.4 fb-1

  10. BsDsK Toy Data from RooFit 6300 events/yr * 5 years B/S ~ 0.5 wBs = 0.334±0.010 eBs = 0.54±0.02 st = 42 fs • = 67o d = 20o Dms = 17.7±0.1 ps-1 DGs = 0.07±0.01 ps-1

  11. BsDsK Fit to Toy Data

  12. Work ongoing • Looking into other Ds decay modes (Liming) • Efficiency • Backgrounds • Can we use BsDs*K ? • Needs further investigation • Develop likelihood fit • Simultaneous fit for Dsp and DsK • First RooFit implementation seems to be working, but more robustness tests needed, pull distributions, etc.

More Related