Decay widths of all MSSM scalars
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Decay widths of all MSSM scalars at full one-loop level. Helmut Eberl together with Hana Hlucha and Wolfgang Frisch. Loops and Legs in QFT, Wörlitz, Germany, 29 th April 2010. Outline. Motivation MSSM, Sfermion/Higgs mass matrices Sfermion/Higgs decays

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Decay widths of all MSSM scalars at full one-loop level

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Decay widths of all mssm scalars at full one loop level

Decay widths of all MSSM scalars

at full one-loop level

Helmut Eberl

together with Hana Hlucha and Wolfgang Frisch

Loops and Legs in QFT, Wörlitz, Germany, 29th April 2010


Decay widths of all mssm scalars at full one loop level

Outline

  • Motivation

  • MSSM, Sfermion/Higgs mass matrices

  • Sfermion/Higgs decays

  • Details of programs

  • Numerics

  • Outlook


Decay widths of all mssm scalars at full one loop level

Program Packages that calculate all MSSM Higgs1 and Sfermion2 decays at full one-loop level

  • Motivation:

    • All SUSY-QCD known, but full EW corr. only for some processes really calculated up to now

    • No complete one-loop code publicly available up to now

    • Total one-loop widths are necessary for 23 one-loop processes with resonant propagators

    • Loops -precision calculation - measurement underlying Lagrangian - next talk by Sven Heinemeyer

[1] PhD thesis W. Frisch

[2] PhD thesis H. Hlucha


Decay widths of all mssm scalars at full one loop level

The Minimal Supersymmetric Standard Model

  • To every SM particle a SUSY partner is introduced, both members of the same multiplet and the d.o.f. are more than doubled.

  • The structure of the SM is automatically included.

  • New particles are predicted, super partners (sparticles) of the SM particles – SUSY models have a rich phenomenology.

Superpotential – generalisation of the Yukawa interactions of the SM:

all fields are here chiral multiplets,

m can be complex

are the 3 x 3 Yukawa matrices

  • Work is done in the “real” 24-parameter MSSM


Decay widths of all mssm scalars at full one loop level

Chiral supermultiplets:

5 phys. Higgs bosons

can mix

can mix

4 neutralinos

2 charginos

Gauge supermultiplets:


Decay widths of all mssm scalars at full one loop level

Interaction states – physical states

Particle mixing: MSSM scalars: Higgs bosons, sfermions

MSSM fermions: charginos, neutralinos

Mass matrices – Eigenvalue problems


Decay widths of all mssm scalars at full one loop level

“decoupling limit”


Decay widths of all mssm scalars at full one loop level

Sfermion sector in the MSSM


Decay widths of all mssm scalars at full one loop level

Two-body decays

possible tree-level structures:

Higgs bosons

scalar

fermion

scalar

scalar

fermion

scalar

vector

scalar

scalar

scalar

vector

vector

Sfermions


Decay widths of all mssm scalars at full one loop level

Higgs couplings to gauge bosons

From the Lagrangian with the covariant derivatives

we get the gauge boson masses

and the couplings with one and two gauge bosons to the Higgs bosons, e.g.

couplings proportional to

In decoupling limit:

0

1


Decay widths of all mssm scalars at full one loop level

Higgs couplings to fermions

Yukawa couplings

Decoupling limit

[1] M. Carena et al, 1999, 2000


Decay widths of all mssm scalars at full one loop level

Renormalization

3 x

=

+

+

+

1loop

ren.

tree

vertex

wave fct. CTs

coupling CTs

only UV div. parts

technical trick

DRbar scheme: UV divergence D = 0

(note: tree-level couplings given at scale Q)

automatic check of

RGE invariance

always on-shell masses


Decay widths of all mssm scalars at full one loop level

Status of calculations

  • flavor conserving MSSM for real input parameters

  • all necessary amplitudes are calculated using FeynArts 3.2/FormCalc 5.3

  • the renormalization is done in the DRbar-scheme following the SPA convention

  • own written counter term file for the whole MSSM

  • automatic generation of fortran code of each channel

  • general Rx gauge implementation

  • hard Bremsstrahlung included with generic formulas

  • MSSM.mod filter to coupling matrices with explicit Yukawa couplings Yuk(type,gen)

  • “naïve” hb = Yuk(4,3) resummation included

  • fortran programs for Higgs and Sfermion widths already work

  • Mathematica link programs exist

  • SUSY spectrum is calculated using SPHENO

    • In- and output in Les Houches Format


S usy p arameter a nalysis project

SUSY Parameter Analysis project*

http//spa.desy.de/spa

In order to get information on fundamental SUSY parameters and

SUSY-breaking mechanism in the MSSM:

observables shall be measured with high accuracy.

LHC – explorer machine

will see SUSY with masses at ~ 1 TeV scale, squark and gluino decays

ILC - high precision machine – requires equally theor. calc. including higher orders

Need of a well-defined theoretical framework:

SPA convention provides a clear base for calculating masses, couplings,

mixing, decay widths and production cross sections.

Program repository

theor. and exp. analyses, LHC+ILC tools, Les Houches Accord

Reference point SPS1a’

*J. A. Aguillar-Saavedra et al., EPJ C46 (2006) 43; see also J. Kalinowski, Acta Phys. Polon. B37 (2006), 1215


Spa convention

SPA convention

  • Massesof SUSY particles and Higgs bosons defined as pole masses

  • All SUSY Lagrangian parameters are in the DRbar scheme at Q = 1TeV

  • All elements in mass matrices, rotation matrices and corresponding mixing angles are def. DRbar at Q, except (h0 –H0) mixing angle is defined on-shell with p = mh0

  • SM input parameters: GFermi, α, mZ, as(mZ) and fermion masses

  • Decay widths/branching ratios and production cross section are calculated for the set of parameters specified above


Decay widths of all mssm scalars at full one loop level

Linear Rx gauge


Decay widths of all mssm scalars at full one loop level

Bremsstrahlung

  • In order to cancel the IR divergencies we have included

  • real photon/gluon radiation:

  • soft radiation – dependent on cut DE, automatized in FC

  • hard radiation – analytic results for integrals used from [1] four generic structures analytically derived and used

The simplest case is scalar -> scalar scalar g/g:

[1] A. Denner, Fortschr. Phys. 41 (1993) 307


Decay widths of all mssm scalars at full one loop level

All numerical results preliminary


Decay widths of all mssm scalars at full one loop level

“SusyHiggsDecay”

Program description:

The program code is written in Fortran 77

  • At the program start the input file config.in is read with the following options:

  • name of Les Houches input file

  • selection of higgs particle: h0 = 1, H0 = 2, A0 = 3 ,H+ = 4, All = 5

  • contribution: tree = 0, full one loop = 1, SQCD = 2

  • bremsstrahlung: off = 0, hard bremsstrahlung = 1, soft bremsstrahlung = 2

  • Higgs masses calculator: tree level masses = 0, SPheno masses = 1, FeynHiggs masses = 2

  • Name of output file

Structure of “SfermionDecay” similar


Reference point sps1a

Reference point SPS1a’

DRbar parameter at Q = 1 TeV


Decay widths of all mssm scalars at full one loop level

mSUGRA benchmark points:

Low Mass points

High Mass points


Decay widths of all mssm scalars at full one loop level

Outlook

First versions of decay programs will be on the web soon!

  • Bottom Yukawa coupling resummation to improve, see [1]

  • Decay with vanishing tree-level, use of (one-loop)2 [2]

  • Higgs sector, input aeff

  • Extension to complex MSSM

  • h0 loop decays – 2loop improvements?

  • leading (strong) 2loop contributions?

  • MSSM fermion decays?

  • developed technique applicable for 2 to 2 and 2 to 3 processes

[1] L. Hofer, U. Nierste, D. Scherer, 2009, [2] S. Bejar, talk at HEPTOOLS meeting, Lisbon 2009


Decay widths of all mssm scalars at full one loop level

Thank you for your attention!


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