34 research outputs found
A New Type of Plasma Wakefield Accelerator Driven by Magnetowaves
We present a new concept for a plasma wakefield accelerator driven by
magnetowaves (MPWA). This concept was originally proposed as a viable mechanism
for the "cosmic accelerator" that would accelerate cosmic particles to ultra
high energies in the astrophysical setting. Unlike the more familiar Plasma
Wakefield Accelerator (PWFA) and the Laser Wakefield Accelerator (LWFA) where
the drivers, the charged-particle beam and the laser, are independently
existing entities, MPWA invokes the high-frequency and high-speed whistler mode
as the driver, which is a medium wave that cannot exist outside of the plasma.
Aside from the difference in drivers, the underlying mechanism that excites the
plasma wakefield via the ponderomotive potential is common. Our computer
simulations show that under appropriate conditions, the plasma wakefield
maintains very high coherence and can sustain high-gradient acceleration over
many plasma wavelengths. We suggest that in addition to its celestial
application, the MPWA concept can also be of terrestrial utility. A
proof-of-principle experiment on MPWA would benefit both terrestrial and
celestial accelerator concepts.Comment: revtex4, 4 pages, 6 figure
Chiral Lagrangians for Radiative Decays of Heavy Hadrons
The radiative decays of heavy mesons and heavy baryons are studied in a
formalism which incorporates both the heavy quark symmetry and the chiral
symmetry. The chiral Lagrangians for the electromagnetic interactions of heavy
hadrons consist of two pieces: one from gauging electromagnetically the
strong-interaction chiral Lagrangian, and the other from the anomalous magnetic
moment interactions of the heavy baryons and mesons. Due to the heavy quark
spin symmetry, the latter contains only one independent coupling constant in
the meson sector and two in the baryon sector. These coupling constants only
depend on the light quarks and can be calculated in the nonrelativistic quark
model. However, the charm quark is not heavy enough and the contribution from
its magnetic moment must be included. Applications to the radiative decays
and are given. Together with our previous results
on the strong decay rates of and , predictions are obtained for the total widths and
branching ratios of and . The decays and are discussed to illustrate the important roles played by both the heavy
quark symmetry and the chiral symmetry.Comment: 30 pages (one figure, available on request), CLNS 92/1158 and
IP-ASTP-13-9
Flavor Changing Neutral Higgs Couplings and Top-Charm Production at Next Linear Collider
We explore the possibility of detecting flavor changing neutral Higgs
couplings at the Next Linear Collider (NLC) through . In the framework of a general two-Higgs doublet model, we perform a
complete calculation and find that could reach fb for . This
amounts to an annual production of 500 plus pairs at the
NLC with an integrated luminosity of 50 fb. The dependence of
-production rate on the neutral scalar mixing angle is mild except when
. The background should be manageable
after -tagging, while background should not be a problem
when the signal event rate is still interesting. The process, together with
studies, offer the
chance of measuring the --Higgs coupling.Comment: REVTEX, 18 pages, 7 figures; Report number change
Effective Lagrangian Approach to Weak Radiative Decays of Heavy Hadrons
Motivated by the observation of the decay by
CLEO, we have systematically analyzed the two-body weak radiative decays of
bottom and charmed hadrons. There exist two types of weak radiative decays: One
proceeds through the short-distance transition and the other
occurs through -exchange accompanied by a photon emission. Effective
Lagrangians are derived for the -exchange bremsstrahlung processes at the
quark level and then applied to various weak electromagnetic decays of heavy
hadrons. Predictions for the branching ratios of and
\Xi_b^0\to\xip_c^0\gamma are given. In particular, we found . Order of magnitude
estimates for the weak radiative decays of charmed hadrons: and
are also presented. Within this approach, the decay asymmetry for antitriplet
to antitriplet heavy baryon weak radiative transitions is uniquely predicted by
heavy quark symmetry. The electromagnetic penguin contribution to
is estimated by two different methods and its
branching ratio is found to be of order . We conclude that
weak radiative decays of bottom hadrons are dominated by the short-distance
mechanism.Comment: 28 pages + 3 figures (not included), CLNS 94/1278, IP-ASTP-04-94.
[Main changes in this revised version: (i) Sect 2 and subsection 4.1 are
revised, (ii) A MIT bag method for calculating the decay rate of is presented, (iii) All predictions are updated using the
newly available 1994 Particle Data Group, and (iv) Appendix and subsections
3.3 and 4.4 are deleted.
Corrections to Chiral Dynamics of Heavy Hadrons: (I) 1/M Correction
In earlier publications we have analyzed the strong and radiative decays of
heavy hadrons in a formalism which incorporates both heavy-quark and chiral
symmetries. In particular, we have derived a heavy-hadron chiral Lagrangian
whose coupling constants are related by the heavy-quark flavor-spin symmetry
arising from the QCD Lagrangian with infinitely massive quarks. In this paper,
we re-examine the structure of the above chiral Lagrangian by including the
effects of corrections in the heavy quark effective theory. The
relations among the coupling constants, originally derived in the heavy-quark
limit, are modified by heavy quark symmetry breaking interactions in QCD. Some
of the implications are discussed.Comment: PHYZZX, 45 pages, 1 figure (not included), CLNS 93/1192,
IP-ASTP-02-93, ITP-SB-93-0
Genetic Variation in the TP53 Pathway and Bladder Cancer Risk. A Comprehensive Analysis
Introduction: Germline variants in TP63 have been consistently associated with several tumors, including bladder cancer,
indicating the importance of TP53 pathway in cancer genetic susceptibility. However, variants in other related genes,
including TP53 rs1042522 (Arg72Pro), still present controversial results. We carried out an in depth assessment of
associations between common germline variants in the TP53 pathway and bladder cancer risk.
Material and Methods: We investigated 184 tagSNPs from 18 genes in 1,058 cases and 1,138 controls from the Spanish
Bladder Cancer/EPICURO Study. Cases were newly-diagnosed bladder cancer patients during 1998–2001. Hospital controls
were age-gender, and area matched to cases. SNPs were genotyped in blood DNA using Illumina Golden Gate and TaqMan
assays. Cases were subphenotyped according to stage/grade and tumor p53 expression. We applied classical tests to assess
individual SNP associations and the Least Absolute Shrinkage and Selection Operator (LASSO)-penalized logistic regression
analysis to assess multiple SNPs simultaneously.
Results: Based on classical analyses, SNPs in BAK1 (1), IGF1R (5), P53AIP1 (1), PMAIP1 (2), SERINPB5 (3), TP63 (3), and TP73 (1)
showed significant associations at p-value#0.05. However, no evidence of association, either with overall risk or with
specific disease subtypes, was observed after correction for multiple testing (p-value$0.8). LASSO selected the SNP
rs6567355 in SERPINB5 with 83% of reproducibility. This SNP provided an OR = 1.21, 95%CI 1.05–1.38, p-value = 0.006, and a
corrected p-value = 0.5 when controlling for over-estimation.
Discussion: We found no strong evidence that common variants in the TP53 pathway are associated with bladder cancer
susceptibility. Our study suggests that it is unlikely that TP53 Arg72Pro is implicated in the UCB in white Europeans.
SERPINB5 and TP63 variation deserve further exploration in extended studies.This work was supported by the Fondo de Investigacion Sanitaria, Spain (grant numbers 00/0745, PI051436, PI061614, G03/174); Red Tematica de Investigacion Cooperativa en Cancer (grant number RD06/0020-RTICC), Spain; Marato TV3 (grant number 050830); European Commission (grant numbers EU-FP7-HEALTH-F2-2008-201663-UROMOL; US National Institutes of Health (grant number USA-NIH-RO1-CA089715); and the Intramural Research Program of the Division of Cancer Epidemiology and Genetics, National Cancer Institute at the National Institutes of Health, USA; Consolider ONCOBIO (Ministerio de Economia y Competitividad, Madrid, Spain). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
Heavy Top Quark Effects in Vertices with Light External Fermions
We extend our previous work on non-linear realization of the top quark field,
which is a consequence of its being much heavier than any other scales. One
loop effective Lagrangian to account for virtual top effects is constructed in
this article, for processes where there are two external fermions, as well as
any number of bosons. Particularly, we focus on those terms which have power
dependence on the top mass .Comment: PHYZZX, 56 pages, IP-ASTP-09-93. Part C of Section 4 has been revise