3,307 research outputs found
Bacteriology of butter lX. Salt distribution in butter and its effect on bacterial growth
The distribution of salt in butter is of importance from the standpoints of uniformity of composition and color, distribution of moisture and deterioration through action of micro-organisms. Various investigators, using macro-methods of analysis, have studied the distribution of salt in butter, particularly in connection with controlling the composition and preventing certain color defects. The information obtained is very useful, but it is not adequate in considering the relationship of salt to bacterial changes in butter.
The retarding effect of salt on the activity of many micro-organisms is generally recognized, and various investigators (8) have· noted that addition of salt to butter limits the action of bacteria in it. However, butter containing relatively high percentages of salt sometimes undergoes bacterial spoilage
Flavor development in salted butter by pure cultures of bacteria preliminary results
Pure cultures of various streptococci produced relatively large amounts of diacetyl and acetylmethylcarbinol in milk containing added citric acid. These included S. citrovorus or S. paracitrovorus, S. diacetilactis, S. citrophilus and an unidentified organism H28. S. aromaticus, which does not ferment citric acid, produced diacetyl and small amounts of acetylmethylcarbinol in milk. With each of the species the ratios of diacetyl to acetylmethylcarbinol varied in the different trials; frequently, the diacetyl was much higher in proportion to the acetylmethylcarbinol than with butter cultures.
The diacetyl contents of cream plus culture immediately after mixing were both higher and lower than the theoretical amounts calculated from the diacetyl contents of the cream and culture; the carbinol contents were about the same as the theoretical values in most trials, but were higher in some instances
Can the Renormalization Group Improved Effective Potential be used to estimate the Higgs Mass in the Conformal Limit of the Standard Model?
We consider the effective potential in the standard model with a single
Higgs doublet in the limit that the only mass scale present is
radiatively generated. Using a technique that has been shown to determine
completely in terms of the renormalization group (RG) functions when using the
Coleman-Weinberg (CW) renormalization scheme, we first sum leading-log (LL)
contributions to using the one loop RG functions, associated with five
couplings (the top quark Yukawa coupling , the quartic coupling of the Higgs
field , the SU(3) gauge coupling , and the couplings
and ). We then employ the two loop RG functions with the three couplings
, , to sum the next-to-leading-log (NLL) contributions to and
then the three to five loop RG functions with one coupling to sum all the
contributions to . In order to compute these sums, it is
necessary to convert those RG functions that have been originally computed
explicitly in the minimal subtraction (MS) scheme to their form in the CW
scheme. The Higgs mass can then be determined from the effective potential: the
result is decreases to at
order and at order. No reasonable
estimate of can be made at orders or . This is taken
to be an indication that this mechanism for spontaneous symmetry breaking is in
fact viable, though one in which there is slow convergence towards the actual
value of . The mass is argued to be an upper bound on
.Comment: 24 pages, 5 figures. Updated version contains new discussion,
references, figures, and corrects errors in reference
Searching for physics beyond the Standard Model through the dipole interaction
The magnetic dipole interaction played a central role in the development of
QED, and continued in that role for the Standard Model. The muon anomalous
magnetic moment has served as a benchmark for models of new physics, and the
present experimental value is larger than the standard-model value by more than
three standard deviations. The electric dipole moment (EDM) violates parity
({}) and time-reversal ({}) symmetries, and in the context of the
theorem, the combination of charge conjugation and parity (). Since a new
source of {} violation outside of that observed in the and meson
systems is needed to help explain the baryon asymmetry of the universe,
searches for EDMs are being carried out worldwide on a number of systems. The
standard-model value of the EDM is immeasurably small, so any evidence for an
EDM would signify the observation of new physics. Unique opportunities exist
for EDM searches using polarized proton, deuteron or muon beams in storage
rings. This talk will provide an overview of the theory of dipole moments, and
the relevant experiments. The connection to the transition dipole moment that
could produce lepton flavor violating interactions such as is also mentioned.Comment: Invited Plenary talk at the 19th International Spin Physics
Symposium, Juelic
A well-separated pairs decomposition algorithm for k-d trees implemented on multi-core architectures
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.Variations of k-d trees represent a fundamental data structure used in Computational Geometry with numerous applications in science. For example particle track tting in the software of the LHC experiments, and in simulations of N-body systems in the study of dynamics of interacting galaxies, particle beam physics, and molecular dynamics in biochemistry. The many-body tree methods devised by Barnes and Hutt in the 1980s and the Fast Multipole Method introduced in 1987 by Greengard and Rokhlin use variants of k-d trees to reduce the computation time upper bounds to O(n log n) and even O(n) from O(n2). We present an algorithm that uses the principle of well-separated pairs decomposition to always produce compressed trees in O(n log n) work. We present and evaluate parallel implementations for the algorithm that can take advantage of multi-core architectures.The Science and Technology Facilities Council, UK
The Discrepancy Between tau and e+e- Spectral Functions Revisited and the Consequences for the Muon Magnetic Anomaly
We revisit the procedure for comparing the pi pi spectral function measured
in tau decays to that obtained in e+e- annihilation. We re-examine the
isospin-breaking corrections using new experimental and theoretical input, and
find improved agreement between the tau- --> pi- pi0 nu_tau branching fraction
measurement and its prediction using the isospin-breaking-corrected e+e- -->
pi+pi- spectral function, though not resolving all discrepancies. We recompute
the lowest order hadronic contributions to the muon g-2 using e+e- and tau data
with the new corrections, and find a reduced difference between the two
evaluations. The new tau-based estimate of the muon magnetic anomaly is found
to be 1.9 standard deviations lower than the direct measurement.Comment: 10 pages, 6 figures, submitted to Eur. Phys. J. C; (v2): Revised
version with improved and uniform treatment of tau and e+e- data with
HVPTools and a few minor bug fixes; (v3): Final version accepted for
publicatio
Reevaluation of the Hadronic Contributions to the Muon g-2 and to alpha(MZ)
We reevaluate the hadronic contributions to the muon magnetic anomaly, and to
the running of the electromagnetic coupling constant at the Z-boson mass. We
include new pi+pi- cross-section data from KLOE, all available multi-hadron
data from BABAR, a reestimation of missing low-energy contributions using
results on cross sections and process dynamics from BABAR, a reevaluation of
all experimental contributions using the software package HVPTools, together
with a reanalysis of inter-experiment and inter-channel correlations, and a
reevaluation of the continuum contributions from perturbative QCD at four
loops. These improvements lead to a decrease in the hadronic contributions with
respect to earlier evaluations. For the muon g-2 we find lowest-order hadronic
contributions of (692.3 +- 4.2) 10^-10 and (701.5 +- 4.7) 10^-10 for the e+e-
based and tau-based analyses, respectively, and full Standard Model predictions
that differ by 3.6 sigma and 2.4 sigma from the experimental value. For the
e+e- based five-quark hadronic contribution to alpha(MZ) we find
Delta_alpha_had[5](MZ)=(275.7 +- 1.0) 10^-4. The reduced electromagnetic
coupling strength at MZ leads to an increase by 7 GeV in the most probable
Higgs boson mass obtained by the standard Gfitter fit to electroweak precision
data.Comment: 13 pages, 10 figures, v2 corrected missing KKpi contribution in Delta
alpha_had(MZ) evaluatio
Charged-Lepton Flavour Physics
This writeup of a talk at the 2011 Lepton-Photon symposium in Mumbai, India,
summarises recent results in the charged-lepton flavour sector. I review
searches for charged-lepton flavour violation, lepton electric dipole moments
and flavour-conserving CP violation. I also discuss recent progress in
tau-lepton physics and in the Standard Model prediction of the muon anomalous
magnetic moment.Comment: Presented at Lepton-Photon 2011, Mumbai, India; 23 pages, 14 figure
Measurement of the CP-violating phase \phi s in Bs->J/\psi\pi+\pi- decays
Measurement of the mixing-induced CP-violating phase phi_s in Bs decays is of
prime importance in probing new physics. Here 7421 +/- 105 signal events from
the dominantly CP-odd final state J/\psi pi+ pi- are selected in 1/fb of pp
collision data collected at sqrt{s} = 7 TeV with the LHCb detector. A
time-dependent fit to the data yields a value of
phi_s=-0.019^{+0.173+0.004}_{-0.174-0.003} rad, consistent with the Standard
Model expectation. No evidence of direct CP violation is found.Comment: 15 pages, 10 figures; minor revisions on May 23, 201
Search for the lepton-flavor-violating decays Bs0âe±Όâ and B0âe±Όâ
A search for the lepton-flavor-violating decays Bs0âe±Όâ and B0âe±Όâ is performed with a data sample, corresponding to an integrated luminosity of 1.0ââfb-1 of pp collisions at âs=7ââTeV, collected by the LHCb experiment. The observed number of Bs0âe±Όâ and B0âe±Όâ candidates is consistent with background expectations. Upper limits on the branching fractions of both decays are determined to be B(Bs0âe±Όâ)101ââTeV/c2 and MLQ(B0âe±Όâ)>126ââTeV/c2 at 95% C.L., and are a factor of 2 higher than the previous bounds
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