Comprehensive study of leptoquark bounds

Journal Article · Sat Jan 01 04:00:00 EST 1994 · Physical Review, D (Particles Fields); (United States)

DOI:https://doi.org/10.1103/PhysRevD.49.333· OSTI ID:5339773

Leurer, M ^[1]

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1. Department of Particle Physics, The Weizmann Institute, Rehovot 76100 (Israel)

We make a comprehensive study of indirect bounds on scalar leptoquarks that couple chirally and diagonally to the first generation by examining available data from low-energy experiments as well as from high energy [ital e][sup +][ital e[minus]] and [ital p[bar p]] accelerators. The strongest bounds turn out to arise from low-energy data: For leptoquarks that couple to right-handed quarks, the most stringent bound comes from atomic parity violation. For leptoquarks that couple to left-handed quarks, there are two mass regions: At low masses the bounds arise from atomic parity violation or from universality in leptonic [pi] decays. At masses above a few hundred GeV's the dominant bounds come from the flavor-changing neutral current (FCNC) processes that are unavoidable in these leptoquarks: The FCNC bound of the up sector, that arises from [ital D][sup 0-][ital [bar D]] [sup 0] mixing, combines with the FCNC bounds from the down sector, that arise from rare [ital K] decays and [ital K][sup 0-][ital [bar K]] [sup 0] mixing, to a bound on the flavor [ital conserving] coupling to the first generation. The bounds restrict leptoquarks that couple with electromagnetic strength to lie above 600 or 630 GeV for leptoquarks that couple to right-handed quarks, and above 1040, 440, and 750 GeV for the SU(2)[sub [ital W]] scalar, doublet, and triplet leptoquarks that couple to left-handed quarks. These bounds are considerably stronger than the first results from the direct searches at the DESY [ital ep] collider HERA. Our bounds also already exclude large regions in the parameter space that could be examined by various methods proposed for indirect leptoquark searches.

• OSTI ID: 5339773
• Journal Information: Physical Review, D (Particles Fields); (United States), Journal Name: Physical Review, D (Particles Fields); (United States) Vol. 49:1; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

662440* -- Properties of Other Particles Including Hypothetical Particles-- (1992-)
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BARYON-BARYON INTERACTIONS
BOUND STATE
CHIRAL SYMMETRY
ELECTRON-POSITRON INTERACTIONS
ELEMENTARY PARTICLES
FERMIONS
HADRON-HADRON INTERACTIONS
INTERACTIONS
LEPTON-LEPTON INTERACTIONS
LEPTONS
NUCLEON-ANTINUCLEON INTERACTIONS
PARITY
PARTICLE INTERACTIONS
PARTICLE PROPERTIES
POSTULATED PARTICLES
PROTON-ANTIPROTON INTERACTIONS
QUARKS
SCALAR FIELDS
SYMMETRY
VIOLATIONS