8,859 research outputs found

### Relativistic Quantum Thermodynamics of Ideal Gases in 2 Dimensions

In this work we study the behavior of relativistic ideal Bose and Fermi gases
in two space dimensions. Making use of polylogarithm functions we derive a
closed and unified expression for their densities. It is shown that both type
of gases are essentially inequivalent, and only in the non-relativistic limit
the spinless and equal mass Bose and Fermi gases are equivalent as known in the
literature.Comment: 6 pages, 1 figur

### Will at least one of the Higgs bosons of the next-to-minimal supersymmetric extension of the Standard Model be observable at LEP2 or the LHC?

We demonstrate that there are regions of parameter space in the
next-to-minimal (i.e. two-Higgs-doublet, one-Higgs-singlet superfield)
supersymmetric extension of the SM for which none of the Higgs bosons are
observable either at LEP2 with $\sqrt{s}=192 GeV$ and an integrated luminosity
of $L=1000 inverse pb$ or at the LHC with $L=600 inverse fb$.Comment: 6 pages, full postscript file also available via anonymous ftp at
ftp://ucdhep.ucdavis.edu/gunion/nmssm_sm96.ps To appear in ``Proceedings of
the 1996 DPF/DPB Summer Study on New Directions for High Energy Physics'

### Approximating the radiatively corrected Higgs mass in the Minimal Supersymmetric Model

To obtain the most accurate predictions for the Higgs masses in the minimal
supersymmetric model (MSSM), one should compute the full set of one-loop
radiative corrections, resum the large logarithms to all orders, and add the
dominant two-loop effects. A complete computation following this procedure
yields a complex set of formulae which must be analyzed numerically. We discuss
a very simple approximation scheme which includes the most important terms from
each of the three components mentioned above. We estimate that the Higgs masses
computed using our scheme lie within 2 GeV of their theoretically predicted
values over a very large fraction of MSSM parameter space.Comment: 31 pages, 10 embedded figures, latex with psfig.sty the complete
postscript file of this preprint, including figures, is available via
anonymous ftp at ftp://www-ttp.physik.uni-karlsruhe.de/ttp95-09/ttp95-09.ps
or via www at http://www-ttp.physik.uni-karlsruhe.de/cgi-bin/preprints

### The Higgs mass in the MSSM infrared fixed point scenario

In the infrared fixed point (IFP) scenario of the minimal supersymmetric
model (MSSM), the top-quark mass and other physical quantities of the
low-energy theory are insensitive to the values of the parameters of the theory
at some high energy scale. In this framework we evaluate the light CP-even
Higgs mass, $m_h$, taking into account some important effects that had not been
previously considered. In particular, the supersymmetric correction to the
relation between the running and the physical top-quark masses lowers the value
of $\tan\beta$, thereby implying a lower predicted value of $m_h$. Assuming a
supersymmetric threshold of $M_S\leq 1$ TeV and $M_t=175$ GeV, we find an upper
bound of $m_h\le 97\pm 2$ GeV; the most plausible value of $m_h$ lies somewhat
below the upper bound. This places the Higgs boson in the IFP scenario well
within the reach of the LEP-2 Higgs search.Comment: 18 pages, LaTeX, 5 ps figures, uses psfig.sty. Final version, some
comments and a figure added, references correcte

### Mass-degenerate Higgs bosons at 125 GeV in the Two-Higgs-Doublet Model

The analysis of the Higgs boson data by the ATLAS and CMS Collaborations
appears to exhibit an excess of h --> gamma\gamma events above the Standard
Model (SM) expectations; whereas no significant excess is observed in h --> ZZ*
--> {four lepton} events, albeit with large statistical uncertainty due to the
small data sample. These results (assuming they persist with further data)
could be explained by a pair of nearly mass-degenerate scalars, one of which is
a SM-like Higgs boson and the other is a scalar with suppressed couplings to
W+W- and ZZ. In the two Higgs doublet model, the observed \gamma\gamma and ZZ*
--> {four lepton} data can be reproduced by an approximately degenerate CP-even
(h) and CP-odd (A) Higgs boson for values of \sin(\beta-\alpha) near unity and
0.7 < \tan\beta < 1. An enhanced \gamma\gamma signal can also arise in cases
where m_h ~ m_H, m_H ~ m_A, or m_h ~ m_H ~ m_A. Since the ZZ* --> {four lepton}
signal derives primarily from a SM-like Higgs boson whereas the \gamma\gamma
signal receives contributions from two (or more) nearly mass-degenerate states,
one would expect a slightly different invariant mass peak in the ZZ* --> {four
lepton} and \gamma\gamma channels. The phenomenological consequences of such
models can be tested with additional Higgs data that will be collected at the
LHC in the near future.Comment: 18 pages, 19 pdf figures, v2: references added, v3&v4: added refs and
explanation

### Derivation of $m_A \simeq M_Z$ and $\tan \beta > \sqrt 3$ in the Minimal Supersymmetric Standard Model

In the minimal supersymmetric standard model, the Higgs sector has two
unknown parameters, usually taken to be $\tan \beta \equiv v_2/v_1$ and $m_A$,
the mass of its one physical pseudoscalar particle. By minimizing the minimum
of the Higgs potential along a certain direction in parameter space, it is
shown that $m_A = M_Z$ + radiative correction, and if one further plausible
assumption is made, $\tan \beta > \sqrt 3$.Comment: 7 pages, University of California, Riverside Report No. UCRHEP-T105
(Feb 1993). [Discussion of radiative correction is now included.

### Charginos and Neutralinos Production at 3-3-1 Supersymmetric Model in $e^-e^-$ Scattering

The goal of this article is to derive the Feynman rules involving charginos,
neutralinos, double charged gauge bosons and sleptons in a 3-3-1 supersymmetric
model. Using these Feynman rules we will calculate the production of a double
charged chargino with a neutralino and also the production of a pair of single
charged charginos, both in an electron- electron $e^-e^-$ process.Comment: 18 pages, 8 figures, 2 table

### Majorana neutrino magnetic moments

The presence of trilinear R-parity violating interactions in the MSSM
lagrangian leads to existence of quark-squark and lepton-slepton loops which
generate mass of the neutrino. By introducing interaction with an external
photon the magnetic moment is obtained. We derive bounds on that quantity being
around one order of magnitude stronger than those present in the literature.Comment: I've decided to move the collection of my papers to arXiv for easier
access. Proceedings of the Nuclear Physics Workshop in Kazimierz Dolny,
Poland, 200

### Decoupling Properties of MSSM particles in Higgs and Top Decays

We study the supersymmetric (SUSY) QCD radiative corrections, at the one-loop
level, to $h^0$, $H^{\pm}$ and t quark decays, in the context of the Minimal
Supersymmetric Standard Model (MSSM) and in the decoupling limit. The
decoupling behaviour of the various MSSM sectors is analyzed in some special
cases, where some or all of the SUSY mass parameters become large as compared
to the electroweak scale. We show that in the decoupling limit of both large
SUSY mass parameters and large CP-odd Higgs mass, the $\Gamma (h^0\to b \bar
b)$ decay width approaches its Standard Model value at one loop, with the onset
of decoupling being delayed for large $\tan\beta$ values. However, this
decoupling does not occur if just the SUSY mass parameters are taken large. A
similar interesting non-decoupling behaviour, also enhanced by $\tan\beta$, is
found in the SUSY-QCD corrections to the $\Gamma (H^+\to t \bar b)$ decay width
at one loop. In contrast, the SUSY-QCD corrections in the $\Gamma (t\to W^+ b)$
decay width do decouple and this decoupling is fast.Comment: 19 pages, 10 figures. Invited talk presented by M.J.Herrero at the
5th International Symposium on Radiative Corrections (RADCOR 2000) Carmel CA,
USA, 11-15 September, 200

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