Download presentation
Presentation is loading. Please wait.
1
Iain Stewart MIT Iain Stewart MIT Nonleptonic Decays and the Soft Collinear Effective Theory Super B Factory Workshop, Hawaii, 2004
2
Text Introduction: What is the Soft-Collinear EFT? 1) Lessons from 2) Factorization for Outlook and Open Issues Clean: Color Suppressed: Baryons: CP violation: Clean: Color Suppressed: Baryons: CP violation: Clean: Color Suppressed: Baryons: CP violation: Clean: Color Suppressed: Baryons: CP violation: Introduction: What is the Soft-Collinear EFT? 1) Lessons from 2) Factorization for Outlook and Open Issues Clean: Color Suppressed: Baryons: CP violation: Clean: Color Suppressed: Baryons: CP violation: Clean: Color Suppressed: Baryons: CP violation: Clean: Color Suppressed: Baryons: CP violation: Outline ie. Factorization Theorem Hard vs. Jet: Polarization: Charming penguins, Power corrections in SCET
3
Two body nonleptonic decays. Simple? Note: Nonleptonic B-decays are not Gold Plated Observables for Lattice QCD
4
Electroweak Hamiltonian = CKM factors
5
1. Use SU(2) or SU(3) to relate amplitudes so data can be used to reduce uncertainties. Flavor symmetries of QCD, 2. Factorization from QCD to reduce the amplitudes to simple universal nonperturbative parameters. Expand in 1. Use SU(2) or SU(3) to relate amplitudes so data can be used to reduce uncertainties. Flavor symmetries of QCD, 2. Factorization from QCD to reduce the amplitudes to simple universal nonperturbative parameters. Expand in Measuring CP violation in “unclean” decays requires These two possibilities are not exclusive. The important thing to keep in mind is “what are the uncertainties”. The important thing to keep in mind is “what are the uncertainties”.
6
Beneke, Buchalla, Neubert, Sachrajda proposed a QCD factorization theorem for, QCDF. Amplitude is reduced to simpler matrix elements At LO in strong phases are perturbative,, and therefore small. Beneke, Buchalla, Neubert, Sachrajda proposed a QCD factorization theorem for, QCDF. Amplitude is reduced to simpler matrix elements At LO in strong phases are perturbative,, and therefore small. Factorization in QCD,,,, form factor hard spectator Keum, Li, Sanda: pQCD Factorization Keum, Li, Sanda: pQCD Factorization
7
PP = 21 + 13 decays PV = 40 + 23 decays VV = 21 + 13 decays PP = 21 + 13 decays PV = 40 + 23 decays VV = 21 + 13 decays Chiang et al. SU(3) analysis QCDF analysis Beneke & Neubert eg.
8
Separate physics at different momentum scales Power expansion Make symmetries explicit Model independent, systematically improvable Separate physics at different momentum scales Power expansion Make symmetries explicit Model independent, systematically improvable Effective Field Theory
9
An effective field theory for energetic hadrons, Soft - Collinear Effective Theory Bauer, Pirjol, Stewart Fleming, Luke Bauer, Pirjol, Stewart Fleming, Luke
10
Soft Collinear Effective Theory eg.
11
Introduce fields for infrared degrees of freedom (in operators) Degrees of freedom in SCET Energetic jets Energetic hadrons
12
Factorization Bauer, Pirjol, I.S. Universal functions: Calculate T,
13
Universal hadronic parameters
14
SCET Expansion
15
Observed 2001 Large - not very predictive Naive Factorization - too small
16
(Cleo, Belle, Babar) Data 20-30% level
17
Color Suppressed Decays Mantry, Pirjol, I.S. ‘03 Factorization with SCET QCD new soft function - like generalized parton distributions QCD
18
Theory: Phenomenology:
19
is complex, new mechanism for rescattering with HQET for get not a convergent expansion
20
Tests and Predictions
21
All predictions so far are independent of the form of and ie. same Br and same strong phases
22
More Predictions
23
nonperturbative strong phases are natural Nonperturbative J vs. Perturbative J With the entire amplitude power suppressed the polarization issue in B to VV is non-trivial nonperturbative strong phases are natural Nonperturbative J vs. Perturbative J With the entire amplitude power suppressed the polarization issue in B to VV is non-trivial Lessons
24
SCET Result
25
Chay, Kim Bauer, Pirjol, Rothstein, I.S. (to appear) operators, exponentiation of soft & collinear gluons hard spectator & form factor terms same operators long distance charming penguins analysis for PP, PV, VV unique function which is also in
26
Operators QCD Integrate out fluctuations...
27
Long Distance dangerous region near threshold,, NRQCD power suppression couple to b, spectator
28
Polarization... ie. SCET agrees with A. Kagan for polarization fraction: No power suppressed unless it is spoiled by charming penguins!
29
Same Jet function as New Nonperturbative Result in : : fit, calculate T’s
30
Hard Coefficients Note: have not used isospin here
31
can use SCET, but there is a lot of work left to do Open Issues in Factorization formula with charming penguins? Role of other degrees of freedom: messenger modes, Glaubers Role of other degrees of freedom: messenger modes, Glaubers ie. Power Corrections: expect nonperturbative phases “chirally” enhanced terms, annihilation Becher, Hill, Neubert
32
Factorization theorems usually do not try to untangle from left in nonperturbative functions Non-analytic terms vanish With all NLO operators, ie all the leading SU(3) violation: Non-analytic terms vanish With all NLO operators, ie all the leading SU(3) violation: Using chiral perturbation theory we find: “Gell-Mann Okubo” all in
33
Outlook SCET We have only seen the tip of the iceberg
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.