7,123 research outputs found
New Types of Thermodynamics from -Dimensional Black Holes
For normal thermodynamic systems superadditivity , homogeneity \H and
concavity \C of the entropy hold, whereas for -dimensional black holes
the latter two properties are violated. We show that -dimensional black
holes exhibit qualitatively new types of thermodynamic behaviour, discussed
here for the first time, in which \C always holds, \H is always violated
and may or may not be violated, depending of the magnitude of the black
hole mass. Hence it is now seen that neither superadditivity nor concavity
encapsulate the meaning of the second law in all situations.Comment: WATPHYS-TH93/05, Latex, 10 pgs. 1 figure (available on request), to
appear in Class. Quant. Gra
Discovering New Physics in the Decays of Black Holes
If the scale of quantum gravity is near a TeV, the LHC will be producing one
black hole (BH) about every second, thus qualifying as a BH factory. With the
Hawking temperature of a few hundred GeV, these rapidly evaporating BHs may
produce new, undiscovered particles with masses ~100 GeV. The probability of
producing a heavy particle in the decay depends on its mass only weakly, in
contrast with the exponentially suppressed direct production. Furthemore, BH
decays with at least one prompt charged lepton or photon correspond to the
final states with low background. Using the Higgs boson as an example, we show
that it may be found at the LHC on the first day of its operation, even with
incomplete detectors.Comment: 4 pages, 3 figure
Estimate of B(K -> pi nu nubar) from Standard Model fits to lambda_t
We estimate B(K -> pi nu nubar) in the context of the Standard Model by
fitting for lambda_t = Vtd x V*ts of the `kaon unitarity triangle' relation. We
fit data from epsilon_K, the CP-violating parameter describing K-mixing, and
a_{psi K}, the CP-violating asymmetry in B -> J/psi K decays. Our estimate is
independent of the CKM matrix element Vcb and of the ratio of Bs to Bd mixing
frequencies. The measured value of B(K+ -> pi+ nu nubar) can be compared both
to this estimate and to predictions made from the ratio of B mixing
frequencies.Comment: 8 pages, including 6 figures. v3 includes an expanded discussion of
correlations between SM inputs to the lambda_t fit, clarifies the discussion
of the independence of this result from the ratio of B mixing frequencies,
includes minor updates to the values of SM input parameters, and includes
some new and some updated reference
Searching for family-number conserving neutral gauge bosons from extra dimensions
Previous studies have shown how the three generations of the Standard Model
fermions can arise from a single generation in more than four dimensions, and
how off-diagonal neutral couplings arise for gauge-boson Kaluza-Klein
recurrences. These couplings conserve family number in the leading
approximation. While an existing example, built on a spherical geometry,
suggests a high compactification scale, we conjecture that the overall
structure is generic, and work out possible signatures at colliders, compatible
with rare decays data.Comment: 4 pages, 2 figures, jetpl.cls style, references adde
Role of five-quark components in radiative and strong decays of the Lambda(1405) resonance
Within an extended chiral constituent quark model, three- and five-quark
structure of the resonance is investigated. Helicity
amplitudes for the electromagnetic decays (, ), and transition amplitudes for
strong decays (, ) are drived, as
well as the relevant decay widths. The experimental value for the strong decay
width, MeV, is well
reproduced with about 50% of five-quark admixture in the .
Important effects due to the configuration mixings among
, and are
found. In addition, transitions between the three- and five-quark components in
the baryons turn out to be significant in both radiative and strong decays of
the resonance.Comment: typos and numerical mistakes corrected, to appear in Phys. Rev.
Two-parameter deformations of logarithm, exponential, and entropy: A consistent framework for generalized statistical mechanics
A consistent generalization of statistical mechanics is obtained by applying
the maximum entropy principle to a trace-form entropy and by requiring that
physically motivated mathematical properties are preserved. The emerging
differential-functional equation yields a two-parameter class of generalized
logarithms, from which entropies and power-law distributions follow: these
distributions could be relevant in many anomalous systems. Within the specified
range of parameters, these entropies possess positivity, continuity, symmetry,
expansibility, decisivity, maximality, concavity, and are Lesche stable. The
Boltzmann-Shannon entropy and some one parameter generalized entropies already
known belong to this class. These entropies and their distribution functions
are compared, and the corresponding deformed algebras are discussed.Comment: Version to appear in PRE: about 20% shorter, references updated, 13
PRE pages, 3 figure
Is it still worth searching for lepton flavor violation in rare kaon decays?
Prospective searches for lepton flavor violation (LFV) in rare kaon decays at
the existing and future intermediate-energy accelerators are considered. The
proposed studies are complementary to LFV searches in muon-decay experiments
and offer a unique opportunity to probe models with approximately conserved
fermion-generation quantum number with sensitivity superior to that in other
processes. Consequently, new searches for LFV in kaon decays are an important
and independent part of the general program of searches for lepton flavor
violation in the final states with charged leptons.Comment: 30 pages, 10 figures. An extended version of the talk given at the
Chicago Flavor Seminar, February 27, 2004. In the new version some misprints
were corrected and some new data for LFV-processes were added. The main
content of the paper was not changed. The paper is published in Yad. Fiz. 68,
1272 (2005
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