Flavour Les Houches Accord

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Purpose of the accord

The objective of this accord is a clear and well-defined structure for interfacing computational tools of "New Physics" models with low-energy flavour calculations. It should hence provide a model-independent parametrization of flavour-related quantities based on the existing SLHA structure. That will allow different programs to talk and to be interfaced, and users to have a clear and well-defined result that can eventually be used for different purposes.

Interested people



The write-up can be found in Write-up page.

New proposal (status 14/11/09)

The latest proposal by Nazila Mahmoudi can be found here.

The previous proposal (07/10/09) by Nazila Mahmoudi can also be found here. A summary of the modifications can be found here.

Discussion of the proposal

First proposal (25/06/09)

Each block's name links to a respective discussion page where you can find more information and make suggestions for modifications and improvements. Please do not modify the current proposal unless a consensus is reached on the discussion subpage. For general comments on the FLHA, not related to a specific block, you can also use the discussion page associated to this page.

NB: FLHA block names generically begin with "F".

Blocks for program and model information

Block FCINFO  # Program information
    1     SUPERISO         # flavour calculator
    2     2.6              # version number
Block FMODSEL   # Model selection
    1     1   # Extradimension (UED)

These blocks are purely informative. They give the code and model used.

Block SM inputs

Block SMINPUTS  # Standard Model inputs
    1     1.27839951e+02   # alpha_em^(-1)
    2     1.16570000e-05   # G_Fermi
    3     1.17200002e-01   # alpha_s(M_Z)
    4     9.11699982e+01   # m_{Z}(pole)
    5     4.19999981e+00   # m_{b}(m_{b})
    6     1.72399994e+02   # m_{top}(pole)
    7     1.77699995e+00   # m_{tau}(pole)

Same as SMINPUTS in the SLHA.

Block Hadron mass spectrum

Block FMASS  # Hadron mass spectrum in GeV
#PDG code  mass             particle
  211     1.39600000e-01   # pi+
  313     8.91700000e-01   # K*
  321     4.93700000e-01   # K+
  421     1.86484000e+00   # D0
  431     1.96849000e+00   # D_s+
  521     5.27950000e+00   # B+
  531     5.36630000e+00   # B_s

This block gives the hadron masses in GeV. The hadrons are labeled with the PDG codes as in the SLHA, but we use a different block name (FMASS) to avoid conflicts.

Block lifetimes

Block FLIFE  # Lifetime in sec 
#PDG code  lifetime         particle
  211     2.60330000e-08   # pi+
  321     1.23800000e-08   # K+
  431     5.00000000e-13   # D_s+
  521     1.63800000e-12   # B+
  531     1.42500000e-12   # B_s

The lifetimes are taken directly from PDG in sec.

Blocks for decay constants

Block FCONST  # Decay constant in GeV
#PDG code  decay constant   particle
  431     2.41000000e-01   # D_s+
  521     2.00000000e-01   # B+
  531     2.45000000e-01   # B_s
Block FCONSTRATIO  # Ratio of decay constant
#PDG code1 code2  ratio    comment
  321 211 1.18900000e+00   # f_K/f_pi

Here we propose to have two blocks, one for the decay constants in GeV and an additional one for ratios of decay constants, which often have less uncertainties. The ratios are specified by the two PDG codes in the form f(code1)/f(code2)

Blocks for Wilson coefficients

Block FWCOEF Q= 1.60846e+02
#Effective Wilson coefficients at scale Q (in GeV) in the basis of hep-ph/..... 
#order   number  value
    0     2      1.00000000e+00
    0     7     -1.82057567e-01
    0     8     -1.06651571e-01
    1     1      2.33177662e+01
    1     4      5.29677461e-01
    1     7      1.35373179e-01
    1     8     -6.94496405e-01
    2     1      3.08498153e+02
    2     2      4.91587899e+01
    2     3     -7.01872509e+00
    2     4      1.25624440e+01
    2     5      8.76122785e-01
    2     6      1.64273022e+00
    2     7      7.05439463e-01
    2     8     -4.65529650e+00

This is the block that needs most discussion. We want to agree on one standard basis to use. Moreover, the Wilson coefficients (WCoefs) should be given order by order at a specific scale (given by Q=... next to the block name). In the above format, the first entry is the order in alpha(s), the second is the number of the WCoef, and the third is the value of the coefficient. An issue open to discussion is whether to put all coefficients into one block or spilt them into several (sub)blocks according to the transition and according to Delta_F=1 and Delta_F=2. See the in-depth discussion page for examples.

Note there can be several such blocks for different scales, e.g.:

Block FWCOEF Q= 2.34384e+00
#Effective Wilson coefficients at scale Q (in GeV) in the basis of hep-ph/..... 
#order   number  value
    0     1     -8.47809531e-01
    0     2      1.06562816e+00
    0     3     -1.34214747e-02
    0     4     -1.29110603e-01
    0     5      1.36343067e-03
    0     6      2.88022278e-03
    0     7     -3.73787589e-01
    0     8     -1.80398551e-01
    1     1      1.52422776e+01
    1     2     -2.13433897e+00
    1     3      9.52880033e-02
    1     4     -4.81776851e-01
    1     5     -2.10727176e-02
    1     6     -1.22929476e-02
    1     7      2.14544819e+00
    1     8     -5.16870265e-01
    2     7      1.98785400e+01

Block Flavour observables

Block FOBS  # Flavour observables
#process observable value
    1     1     2.97350499e-04   # BR(b->s gamma)
    1     2     8.25882011e-02   # Delta0(B->K* gamma)
    2     1     3.46978963e-09   # BR(B_s->mu+ mu-)
    3     1     1.09699841e-04   # BR(B_u->tau nu)
    3     2     9.96640362e-01   # R(B_u->tau nu)
    4     1     6.96556180e-03   # BR(B+->D0 tau nu)
    4     2     2.97261612e-01   # BR(B+->D0 tau nu)/BR(B+-> D0 e nu)
    5     1     4.81251996e-02   # BR(D_s->tau nu)
    6     1     4.96947301e-03   # BR(D_s->mu nu)
    7     1     6.45414388e-01   # BR(K->mu nu)/BR(pi->mu nu)
    7     2     9.99985822e-01   # R_l23

The first column here specifies the underlying process (e.g. b to s gamma) and the second column defines the observable (e.g. BR, isospin,...). The numbering of the processes and observables is not set yet.

Block theoretical errors

Block FOBSERR  # Theoretical error for flavour observables
#process observable error
    1     1     0.23e-04   # BR(b->s gamma)

Minutes of meetings

Les Houches, first meeting, 19 June 2009 3:00pm

slides [1]

minutes [2]

Les Houches, second meeting, 24 June 2009 3:00pm

slides [3]

minutes [4]

Useful Links

Official Web Page of the SUSY Les Houches Accord

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