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Interference effects in BSM processes with a generalised narrow-width approximation.

Fuchs E, Thewes S, Weiglein G - Eur Phys J C Part Fields (2015)

Bottom Line: It is demonstrated that interference effects of this kind arising in BSM models can be very large, leading to drastic modifications of predictions based on the standard NWA.The generalised NWA, based on on-shell matrix elements or their approximations leading to simple weight factors, is shown to produce UV- and IR-finite results which are numerically close to the result of the full process at tree level and at one-loop order, where an agreement of better than [Formula: see text] is found for the considered process.The most accurate prediction for this process based on the generalised NWA, taking into account also corrections that are formally of higher orders, is briefly discussed.

View Article: PubMed Central - PubMed

Affiliation: DESY, Deutsches Elektronen-Synchrotron, Notkestr. 85, 22607 Hamburg, Germany.

ABSTRACT

A generalisation of the narrow-width approximation (NWA) is formulated which allows for a consistent treatment of interference effects between nearly mass-degenerate particles in the factorisation of a more complicated process into production and decay parts. It is demonstrated that interference effects of this kind arising in BSM models can be very large, leading to drastic modifications of predictions based on the standard NWA. The application of the generalised NWA is demonstrated both at tree level and at one-loop order for an example process where the neutral Higgs bosons h and H of the MSSM are produced in the decay of a heavy neutralino and subsequently decay into a fermion pair. The generalised NWA, based on on-shell matrix elements or their approximations leading to simple weight factors, is shown to produce UV- and IR-finite results which are numerically close to the result of the full process at tree level and at one-loop order, where an agreement of better than [Formula: see text] is found for the considered process. The most accurate prediction for this process based on the generalised NWA, taking into account also corrections that are formally of higher orders, is briefly discussed.

No MeSH data available.


Related in: MedlinePlus

Example triangle diagrams of the 3-body decay  with 1-loop corrections at the -vertex, where  denotes a Higgs boson mixed by -factors,  an internal Higgs boson (see text) and . u and  represent the up-type (s)quarks,  are the neutralinos and  the charginos
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Fig6: Example triangle diagrams of the 3-body decay with 1-loop corrections at the -vertex, where denotes a Higgs boson mixed by -factors, an internal Higgs boson (see text) and . u and represent the up-type (s)quarks, are the neutralinos and the charginos

Mentions: Virtual SM and MSSM particles contribute to the correction of the -vertex. A selection of diagrams is displayed in Fig. 6. We treat here the intermediate Higgs bosons appearing outside of the vertex loop contribution as “external”, while denotes an internal Higgs boson within the loop (). Furthermore, denotes the charged Higgs bosons. The neutralinos are labelled by and the charginos by . The first example diagram contains up-type quarks and a squark of generation .Fig. 6


Interference effects in BSM processes with a generalised narrow-width approximation.

Fuchs E, Thewes S, Weiglein G - Eur Phys J C Part Fields (2015)

Example triangle diagrams of the 3-body decay  with 1-loop corrections at the -vertex, where  denotes a Higgs boson mixed by -factors,  an internal Higgs boson (see text) and . u and  represent the up-type (s)quarks,  are the neutralinos and  the charginos
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4464706&req=5

Fig6: Example triangle diagrams of the 3-body decay with 1-loop corrections at the -vertex, where denotes a Higgs boson mixed by -factors, an internal Higgs boson (see text) and . u and represent the up-type (s)quarks, are the neutralinos and the charginos
Mentions: Virtual SM and MSSM particles contribute to the correction of the -vertex. A selection of diagrams is displayed in Fig. 6. We treat here the intermediate Higgs bosons appearing outside of the vertex loop contribution as “external”, while denotes an internal Higgs boson within the loop (). Furthermore, denotes the charged Higgs bosons. The neutralinos are labelled by and the charginos by . The first example diagram contains up-type quarks and a squark of generation .Fig. 6

Bottom Line: It is demonstrated that interference effects of this kind arising in BSM models can be very large, leading to drastic modifications of predictions based on the standard NWA.The generalised NWA, based on on-shell matrix elements or their approximations leading to simple weight factors, is shown to produce UV- and IR-finite results which are numerically close to the result of the full process at tree level and at one-loop order, where an agreement of better than [Formula: see text] is found for the considered process.The most accurate prediction for this process based on the generalised NWA, taking into account also corrections that are formally of higher orders, is briefly discussed.

View Article: PubMed Central - PubMed

Affiliation: DESY, Deutsches Elektronen-Synchrotron, Notkestr. 85, 22607 Hamburg, Germany.

ABSTRACT

A generalisation of the narrow-width approximation (NWA) is formulated which allows for a consistent treatment of interference effects between nearly mass-degenerate particles in the factorisation of a more complicated process into production and decay parts. It is demonstrated that interference effects of this kind arising in BSM models can be very large, leading to drastic modifications of predictions based on the standard NWA. The application of the generalised NWA is demonstrated both at tree level and at one-loop order for an example process where the neutral Higgs bosons h and H of the MSSM are produced in the decay of a heavy neutralino and subsequently decay into a fermion pair. The generalised NWA, based on on-shell matrix elements or their approximations leading to simple weight factors, is shown to produce UV- and IR-finite results which are numerically close to the result of the full process at tree level and at one-loop order, where an agreement of better than [Formula: see text] is found for the considered process. The most accurate prediction for this process based on the generalised NWA, taking into account also corrections that are formally of higher orders, is briefly discussed.

No MeSH data available.


Related in: MedlinePlus