7,846 research outputs found
Complete High Temperature Expansions for One-Loop Finite Temperature Effects
We develop exact, simple closed form expressions for partition functions
associated with relativistic bosons and fermions in odd spatial dimensions.
These expressions, valid at high temperature, include the effects of a
non-trivial Polyakov loop and generalize well-known high temperature
expansions. The key technical point is the proof of a set of Bessel function
identities which resum low temperature expansions into high temperature
expansions. The complete expressions for these partition functions can be used
to obtain one-loop finite temperature contributions to effective potentials,
and thus free energies and pressures.Comment: 9 pages, RevTeX, no figures. To be published in Phys. Rev D. v2 has
revised introduction and conclusions, plus a few typographical errors are
corrected; v3 corrects one typ
Zero gravity and cardiovascular homeostasis. The relationship between endogenous hyperprolactinemia and plasma aldosterone
Prolactin, thyrotropin and aldosterone were measured by radioimmunoassay and plasma renin activity by the radioimmunoassay of angiotensin I in normal women before and after the intravenous injection of 200 micrograms of thyrotropin releasing hormone. Prolactin increased at 15 minutes following thyrotropin releasing hormone. Plasma renin activity was not different from control levels during the first hour following the administration of thyrotropin releasing hormone, nor did the plasma aldosterone concentration differ significantly from the control levels during this period. However, with upright posture, an increase in aldosterone and in plasma renin activity was noted, demonstrating a normal capacity to secrete aldosterone. Similarly, no change in aldosterone was seen in 9 patients with primary hypothyroidism given thyrotropin releasing hormone, despite the fact that the increase in prolactin was greater than normal. These data demonstrate that acutely or chronically elevated serum prolactin levels do not result in increased plasma aldosterone levels in humans
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
Sneutrino Mixing Phenomena
In any model with nonzero Majorana neutrino masses, the sneutrino and
antisneutrino of the supersymmetric extended theory mix. We outline the
conditions under which sneutrino-antisneutrino mixing is experimentally
observable. The mass-splitting of the sneutrino mass eigenstates and sneutrino
oscillation phenomena are considered.Comment: 12 pages, revtex + axodraw, 1 figure included. Minor change
Conditions for CP-Violation in the General Two-Higgs-Doublet Model
The most general Higgs potential of the two-Higgs-doublet model (2HDM)
contains three squared-mass parameters and seven quartic self-coupling
parameters. Among these, one squared-mass parameter and three quartic coupling
parameters are potentially complex. The Higgs potential explicitly violates CP
symmetry if and only if no choice of basis exists in the two-dimensional Higgs
``flavor'' space in which all the Higgs potential parameters are real. We
exhibit four independent potentially complex invariant (basis-independent)
combinations of mass and coupling parameters and show that the reality of all
four invariants provides the necessary and sufficient conditions for an
explicitly CP-conserving 2HDM scalar potential. Additional potentially complex
invariants can be constructed that depend on the Higgs field vacuum expectation
values (vevs). We demonstrate how these can be used together with the
vev-independent invariants to distinguish between explicit and spontaneous
CP-violation in the Higgs sector.Comment: 46 pages, minor typographical errors corrected, accepted for
publication in Phys. Rev.
Frontostriatal Maturation Predicts Cognitive Control Failure to Appetitive Cues in Adolescents
Adolescent risk-taking is a public health issue that increases the odds of poor lifetime outcomes. One factor thought to influence adolescents' propensity for risk-taking is an enhanced sensitivity to appetitive cues, relative to an immature capacity to exert sufficient cognitive control. We tested this hypothesis by characterizing interactions among ventral striatal, dorsal striatal, and prefrontal cortical regions with varying appetitive load using fMRI scanning. Child, teen, and adult participants performed a go/no-go task with appetitive (happy faces) and neutral cues (calm faces). Impulse control to neutral cues showed linear improvement with age, whereas teens showed a nonlinear reduction in impulse control to appetitive cues. This performance decrement in teens was paralleled by enhanced activity in the ventral striatum. Prefrontal cortical recruitment correlated with overall accuracy and showed a linear response with age for no-go versus go trials. Connectivity analyses identified a ventral frontostriatal circuit including the inferior frontal gyrus and dorsal striatum during no-go versus go trials. Examining recruitment developmentally showed that teens had greater between-subject ventral-dorsal striatal coactivation relative to children and adults for happy no-go versus go trials. These findings implicate exaggerated ventral striatal representation of appetitive cues in adolescents relative to an intermediary cognitive control response. Connectivity and coactivity data suggest these systems communicate at the level of the dorsal striatum differentially across development. Biased responding in this system is one possible mechanism underlying heightened risk-taking during adolescence
Electroweak Symmetry Breaking and BSM Physics (A Review)
In this talk, I shall first discuss the standard model Higgs mechanism and
then highlight some of its deficiencies making a case for the need to go beyond
the standard model (BSM). The BSM tour will be guided by symmetry arguments. I
shall pick up four specific BSM scenarios, namely, supersymmetry, Little Higgs,
Gauge-Higgs unification, and the Higgsless approach. The discussion will be
confined mainly on their electroweak symmetry breaking aspects.Comment: 17 pages, 10 eps figs, Based on plenary talks at the International
Conferences: WIN07, Kolkata, Jan'07, and WHEPP-10, Chennai, Jan'08. To appear
in the WHEPP-10 proceedings (a special issue of PRAMANA
Calculable Upper Limit on the Mass of the Lightest Higgs Boson in Any Perturbatively Valid Supersymmetric Theory
We show that there is a calculable upper limit on the mass of the lightest
Higgs boson in any supersymmetric theory that remains perturbative up to a high
scale . There are no restrictions on the Higgs sector, or the gauge group or
particle content. We estimate the value of the upper limit to be m_{\hcirc} <
146 GeV for 100 GeV < < 145 GeV, from all effects except possibly
additional heavy fermions beyond top (which could increase the limit by 0-20
GeV if any existed); for > 145 GeV the limit decreases monotonically. We
expect to be able to decrease the value of the upper limit by at least a few
percent by very careful analysis of the conditions. It is not normal in models
for the actual mass to saturate the upper limit.Comment: 8 pages, UM-TH-92-24, Plain TeX. (One table available by fax on
request to [email protected]
The Impacts of Ecotourism on Sustentateur Development and Economic Prosperity in the Kesrouan_Ftouh Region of Mount Lebanon
Radiative Neutralino Decay in Split Supersymmetry
Radiative neutralino decay is studied in a Split
Supersymmetric scenario, and compared with mSUGRA and MSSM. This 1-loop process
has a transition amplitude which is often quite small, but has the advantage of
providing a very clear and distinct signature: electromagnetic radiation plus
missing energy. In Split Supersymmetry this radiative decay is in direct
competition with the tree-level three-body decay , and we obtain large values for the branching ratio which can be close to unity in the region .
Furthermore, the value for the radiative neutralino decay branching ratio has a
strong dependence on the split supersymmetric scale , which is
otherwise very difficult to infer from experimental observables.Comment: 15 pages and 10 figure
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