hep-ph daily 9612485 -- 9612490 received (over 2608 served) 1626
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received from Mon 30 Dec 96 01:00:02 GMT to Tue 31 Dec 96 01:00:02 GMT
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Paper: hep-ph/9612485
From: Yumian Su <yum...@budoe.bu.edu>
Date: Mon, 30 Dec 1996 04:57:45 -0500 (EST)
Title: $B \to X_s \mu^+ \mu^-$ in Technicolor with Scalars
Author: Yumian Su
Comments: 19 pages, LaTeX, includes 6 figures
Report-no: BUHEP-96-48
\\
We compute the flavor changing neutral current process $B \to X_s \mu^+
\mu^-$ in technicolor models with scalars. We find that the branching ratio can
be enhanced relative to that of the Standard Model by as much as 60%. The
full parameter space of the model is consistent with the present CLEO and CDF
exclusive limits. However, the viability of the model could soon be tested
since the decay signals are expected to be observed in the next few years with
the upgraded CLEO detector and in the CDF Run II.
\\ (http://xxx.lanl.gov/abs/hep-ph/9612485 , 28kb)
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Paper: hep-ph/9612486
From: max...@hadron.tp2.ruhr-uni-bochum.de (Maxim Polyakov)
Date: Mon, 30 Dec 1996 14:28:33 +0100
Title: Chiral expansion in the dual (string) models of the Goldstone meson
scattering
Authors: M.V. Polyakov, and G. Weidl
Comments: 13 pages, no figures
\\
We consider in details the dual models for the Goldstone mesons (pions)
scattering in the presence of the explicit chiral symmetry breaking caused by
non-zero current quark mass. New method of incorporation of the quark masses
into the dual model is suggested. In contrast to the previously considered in
the literature methods, the dual amplitude obtained by this method is
consistent with all low-energy theorems following from the Effective Chiral
Lagrangian (EChL) to the O(p^4) order and simultaneously it does not contain
states with negative width. The resonance spectrum of the model and its
implications for the fourth and sixth order EChL in large N_c limit are
discussed. We argue that the possible relations between large N_c QCD and some
underlying string theory can be revealed by studying interactions of hadrons at
low-energies.
\\ (http://xxx.lanl.gov/abs/hep-ph/9612486 , 12kb)
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Paper: hep-ph/9612487
From: Antonio Ferrera <cee...@pinar2.csic.es>
Date: Mon, 30 Dec 1996 09:04:32 MST
Title: Defect Formation in First Order Phase Transitions with Damping
Authors: Antonio Ferrera (Consejo Superior de Investigaciones Cientificas,
Madrid)
Comments: 10 Latex pages, 9 figures available on request
\\
Within the context of first order phase transitions in the early universe, we
study the influence of a coupling between the (global U(1)) scalar driving the
transition and the rest of the matter content of the theory. The effect of the
coupling on the scalar is simulated by introducing a damping term in its
equations of motion, as suggested by recent results in the electroweak phase
transition. After a preceeding paper, in which we studied the influence that
this coupling has in the dynamics of bubble collisions and topological defect
formation, we proceed in this paper to quantify the impact of this new effects
on the probability of defect creation per nucleating bubble.
\\ (http://xxx.lanl.gov/abs/hep-ph/9612487 , 14kb)
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Paper: hep-ph/9612488
From: iv...@garm.physics.carleton.ca (Ivan Melo)
Date: Mon, 30 Dec 1996 13:14:08 -0500
Title: The phenomenology of neutral heavy leptons
Authors: Ivan Melo
Comments: Ph.D. thesis, 170 pages, LaTeX, 34 figures (embedded)
\\
Naturally small neutrino masses can arise in some grand unified models. The
mechanism of neutrino mass generation in these models typically requires the
existence of neutral heavy leptons. We study the low-energy phenomenology of
these new fermions. Concentrating on loop corrections due to neutral heavy
leptons, we examine how the flavour-conserving leptonic decays of the Z boson,
universality breaking in these decays, and the W boson mass depend on the mass
and mixings of the neutral heavy leptons. Working within the framework of a
superstring-inspired SU(2)_L x U(1)_Y model, we show that these
flavour-conserving processes have some virtues over the traditionally
considered flavour-violating decays.
\\ (http://xxx.lanl.gov/abs/hep-ph/9612488 , 184kb)
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Paper: hep-ph/9612489
From: "A.A.Penin" <pe...@ms2.inr.ac.ru>
Date: Mon, 30 Dec 1996 23:09:33 +0300 (MSK)
Title: Practical techniques of QCD vs exact results of solvable models
Authors: A.A.Penin and A.A.Pivovarov
Comments: 27 pages, 4 figures, Latex
Report-no: INR 937/96
\\
We check quantitatively the validity of some popular phenomenological
approaches of QCD in simple models. Dispersion sum rules are considered within
the ladder approximation of a field-theoretic model with OPE given by ordinary
loop diagrams which are computable for any number of loops. A correlator of two
currents within the model complies with all requirements of standard QCD sum
rules approach for fitting low-lying resonances such as fast convergence and
good stability while the exact spectrum contains no resonance. Optimized PT as
it is inspired by the principle of minimal sensitivity is analyzed within a
quantum mechanical model and is shown to work well as compared to pure
asymptotic expansion in the coupling constant or Pad\'e approximation.
Renormalon technique is tested within another quantum mechanical model and is
found to fail to detect its low-energy structure.
\\ (http://xxx.lanl.gov/abs/hep-ph/9612489 , 153kb)
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Paper: hep-ph/9612490
From: SHI...@physics.spa.umn.edu
Date: Mon, 30 Dec 1996 15:46:02 -0600 (CST)
Title: A More Minimal Messenger Model of Gauge-Mediated Supersymmetry Breaking?
Authors: G. Dvali and M. Shifman
Comments: 10 pages, LATEX, no figures
Report-no: TPI-MINN-96/29-T
\\
This Letter addresses a provocative question: ``Can the standard electroweak
Higgs doublets and their color-triplet partners be the messengers of a low
energy gauge-mediated SUSY breaking?" Such a possibility does not seem to be
immediately ruled out. If so, it can lead to a very economical scheme with
clear-cut predictions quite distinct from those of the conventional
gauge-mediated scenario. Namely, we get (i) a single light Higgs below the
original SUSY- breaking scale; (ii) tan(beta) = 1; (iii) flavor non-universal,
but automatically flavor-conserving soft scalar masses; (iv) a light colored
scalar with peculiar phenomenology. The familiar mu problem looses its meaning
in this approach.
\\ (http://xxx.lanl.gov/abs/hep-ph/9612490 , 12kb)
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Paper (*cross-listing*): astro-ph/9612222
From: Gunter Sigl <si...@oddjob.uchicago.edu>
Date: Mon, 23 Dec 1996 11:27:00 -0600
Title: A Fresh Look at Axions and SN 1987A
Authors: Wolfgang Keil, Hans-Thomas Janka (MPA, Muenchen), David N. Schramm,
Guenter Sigl, Michael S. Turner (Univ. of Chicago), John Ellis (CERN)
Comments: 32 latex pages, 13 postscript figures included, uses revtex.sty,
submitted to Physical Review D
Report-no: FNAL-Pub-95/406-A, CERN-TH/96-112
\\
We re-examine the very stringent limits on the axion mass based on the
strength and duration of the neutrino signal from SN 1987A, in the light of new
measurements of the axial-vector coupling strength of nucleons, possible
suppression of axion emission due to many-body effects, and additional emission
processes involving pions. The suppression of axion emission due to nucleon
spin fluctuations induced by many-body effects degrades previous limits by a
factor of about 2. Emission processes involving thermal pions can strengthen
the limits by a factor of 3-4 within a perturbative treatment that neglects
saturation of nucleon spin fluctuations. Inclusion of saturation effects,
however, tends to make the limits less dependent on pion abundances. The
resulting axion mass limit also depends on the precise couplings of the axion
and ranges from 0.5x10**(-3) eV to 6x10**(-3) eV.
\\ (http://xxx.lanl.gov/abs/astro-ph/9612222 , 220kb)
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Paper (*cross-listing*): astro-ph/9612237
From: Kazunori Kohri <ko...@ctsun2.icrr.u-tokyo.ac.jp>
Date: Sun, 29 Dec 1996 18:26:03 +0900
Date (revised): Mon, 30 Dec 1996 17:56:06 +0900
Title: Big Bang Nucleosynthesis and Lepton Number Asymmetry in the Universe
Authors: K. Kohri, M. Kawasaki and Katsuhiko Sato
Comments: 10 pages, using AAS LATEX and three postscript figures
\\
Recently it is reported that there is the discrepancy between big bang
nucleosynthesis theory and observations (BBN crisis). We show that BBN
predictions agree with the primordial abundances of light elements, ${}^4$He,
D, ${}^3$He ~and ${}^7$Li inferred from the observational data if an electron
neutrino has a net chemical potential $\xi_{\nu_e}$ due to lepton asymmetry. We
estimate that $\xi_{\nu_e} = 0.043^{+0.040}_{-0.040}$ (95% C.L.) and
$\Omega_bh^2 = 0.015^{+0.006}_{-0.003}$ (95% C.L.).
\\ (http://xxx.lanl.gov/abs/astro-ph/9612237 , 43kb)
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Paper (*cross-listing*): nucl-th/9612063
From: Silvano Simula <sim...@hpteo2.iss.infn.it>
Date: Fri, 27 Dec 96 17:35:14 MET
Title: Light-front CQM calculations of baryon electromagnetic form factors
Authors: F. Cardarelli, E. Pace, G. Salm\'e and S. Simula
Comments: to appear in the Proceedings of the International Workshop on Hadron
Dynamics with the new DAPHNE and CEBAF facilities, Frascati, Italy, 11-14
November 1996
Report-no: preprint INFN-ISS 96/12
\\
The parameter-free predictions for the $N - P_{11}(1440)$ and $N -
P_{33}(1232)$ electromagnetic transition form factors, obtained within our
light-front constituent quark model using eigenfunctions of a baryon mass
operator which includes a large amount of configuration mixing, are reported.
The effects due to small components in the baryon wave functions, such as S'-
and D-wave, are also investigated.
\\ (http://xxx.lanl.gov/abs/nucl-th/9612063 , 82kb)
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Comments: 3 pages, latex, no figures, mpeg simulations available at
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Report-no: EFI-96-40
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