1,617 research outputs found
Shift in the LHC Higgs diphoton mass peak from interference with background
The Higgs diphoton amplitude from gluon fusion at the LHC interferes with the
continuum background induced by quark loops. I investigate the effect of this
interference on the position of the diphoton invariant mass peak used to help
determine the Higgs mass. At leading order, the interference shifts the peak
towards lower mass by an amount of order 150 MeV or more, with the precise
value dependent on the methods used to analyze and fit the data.Comment: 10 pages. v2: comments on scale variation added, reference adde
Studying Critical String Emerging from Non-Abelian Vortex in Four Dimensions
Recently a special vortex string was found [5] in a class of soliton vortices
supported in four-dimensional Yang-Mills theories that under certain conditions
can become infinitely thin and can be interpreted as a critical ten-dimensional
string. The appropriate bulk Yang-Mills theory has the U(2) gauge group and the
Fayet-Iliopoulos term. It supports semilocal non-Abelian vortices with the
world-sheet theory for orientational and size moduli described by the weighted
CP(2,2) model. The full target space is R_4\times Y_6 where Y_6 is a
non-compact Calabi-Yau space.
We study the above vortex string from the standpoint of string theory,
focusing on the massless states in four dimensions. In the generic case all
massless modes are non-normalizable, hence, no massless gravitons or vector
fields are predicted in the physical spectrum. However, at the selfdual point
(at strong coupling) weighted CP(2,2) admits deformation of the complex
structure, resulting in a single massless hypermultiplet in the bulk. We
interpret it as a composite "baryon."Comment: 15 pages, no figures, minor correction
Exact Superpotentials, Quantum Vacua and Duality in Supersymmetric SP(N_c) Gauge Theories
We study supersymmetric gauge theories with flavors of
quarks in the fundamental representation. Depending on and , we find
exact, dynamically generated superpotentials, smooth quantum moduli spaces of
vacua, quantum moduli spaces of vacua with additional massless composites at
strong coupling, confinement without chiral symmetry breaking, non-trivial
fixed points of the renormalization group, and massless magnetic quarks and
gluons.Comment: 10 pages, harvma
On Quark-Hadron Duality in the Heavy Quark Sector
I discuss the issue of quark-hadron duality in the system of heavy-light
quark mesons. As an example, I consider a correlator of two currents comprising
heavy quark operators, and I compare the OPE expression with the result
obtained by a complete insertion of hadronic states. After a smearing
procedure, OPE and hadronic spectral functions agree with each other. However,
the local behaviour of the two functions is different, and the difference
manifests itself in a term which is absent in the OPE.Comment: 5 pages, LaTeX, 1 postscript figure, uses espcrc2.sty. To appear in
the Proceedings of the High Energy Physics Euroconference QCD'97,
Montpellier, France, 3-9 July 199
N=(0,2) Deformation of the N=(2,2) Wess-Zumino Model in Two Dimensions
We construct a simple N=(0,2) deformation of the two-dimensional Wess-Zumino
model. In addition to superpotential, it includes a "twisted" superpotential.
Supersymmetry may or may not be spontaneously broken at the classical level. In
the latter case an extra right-handed fermion field \zeta_R involved in the
N=(0,2) deformation plays the role of Goldstino.Comment: 6 pages; v2: 3 references added; final version accepted for
publication in PR
Resonance-continuum interference in the di-photon Higgs signal at the LHC
A low mass Standard Model Higgs boson should be visible at the Large Hadron
Collider through its production via gluon-gluon fusion and its decay to two
photons. We compute the interference of this resonant process, gg -> H -> gamma
gamma, with the continuum QCD background, gg -> gamma gamma induced by quark
loops. Helicity selection rules suppress the effect, which is dominantly due to
the imaginary part of the two-loop gg -> gamma gamma scattering amplitude. The
interference is destructive, but only of order 5% in the Standard Model, which
is still below the 10-20% present accuracy of the total cross section
prediction. We comment on the potential size of such effects in other Higgs
models.Comment: 10 pages, 2 figure
The Isgur-Wise Function to from Sum Rules in the Heavy Quark Effective Theory
Radiative corrections to both perturbative and non-perturbative contributions
are added to existing calculations of the Isgur-Wise function . To
this end, we develop a method for calculating two-loop integrals in the heavy
quark effective theory involving two different scales. The inclusion of
terms causes to decrease as compared to the lowest
order result and shows the importance of quantum effects. The slope parameter
violates the bound given by de Rafael and Taron.Comment: 11 pages, 2 figures (not included), (LaTeX), HD-THEP-92-4
On the Inconsistency of Fayet-Iliopoulos Terms in Supergravity Theories
Motivated by recent discussions, we revisit the issue of whether globally
supersymmetric theories with non-zero Fayet-Iliopoulos terms may be
consistently coupled to supergravity. In particular, we examine claims that a
fundamental inconsistency arises due to the conflicting requirements which are
imposed on the -symmetry properties of the theory by the supergravity
framework. We also prove that certain kinds of Fayet-Iliopoulos contributions
to the supercurrent supermultiplets of theories with non-zero Fayet-Iliopoulos
terms fail to exist. A key feature of our discussion is an explicit comparison
between results from the chiral (or ``old minimal'') and linear (or ``new
minimal'') formulations of supergravity, and the effects within each of these
formalisms that are induced by the presence of non-zero Fayet-Iliopoulos terms.Comment: Comments: 69 pages, LaTeX, 2 figures, 7 tables. Significant new
material on conformal-compensator formalisms added, previous results
clarified and extended, references adde
Analytic calculation of Witten index in D=2 supersymmetric Yang-Mills quantum mechanics
We propose a method for the evaluation of Witten index in D=2 supersymmetric
Yang-Mills quantum mechanics. We rederive a known result for the SU(2) gauge
group and generalize it to any SU(N) gauge group.Comment: 21 pages, 5 figure
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