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1. chinaXiv:201609.01013 [pdf]

Perturbativity Limits for Scalar Minimal Dark Matter with Yukawa Interactions: Septuplet

Chengfeng Cai; Ze-Min Huang; Zhaofeng Kang; Zhao-Huan Yu; Hong-Hao Zhang
Subjects: Physics >> Nuclear Physics

The candidate of minimal dark matter (MDM) is limited if one demands perturbativity up to a very high scale, and it was believed that the MDM model with a real scalar septuplet could keep perturbative up to the Planck or GUT scale. In this work we point out that it is not true after taking into account the running of the quartic self-couplings of the scalar septuplet. For the septuplet mass around?10?TeV, which is suggested by the observed dark matter relic abundance, these couplings would hit the Landau pole at a scale??108?109?GeV, much lower than the Planck scale. We attempt to push up the Landau pole scale as high as possible by proposing an extension with extra Yukawa interactions of the septuplet. We find that in principle the Landau pole could be deferred to a scale of??1014?GeV if one could tolerate a serious fine-tuning of the initial condition of the Yukawa coupling. Moreover, if the MDM particle mass could be relaxed to??108?GeV, which would need some nonthermal production mechanisms to give a correct relic abundance, the Landau pole scale could be pushed up above the Planck scale.

submitted time 2016-09-14 Hits1356Downloads794 Comment 0

2. chinaXiv:201605.00998 [pdf]

Quantifying the sequence-function relation in gene silencing by bacterial small RNAs

Yue Hao; Zhongge J. Zhang; David W. Erickson; Min Huang; Yingwu Huang; Junbai Li; Terence Hwa; hualin shi
Subjects: Physics >> Interdisciplinary Physics and Related Areas of Science and Technology

Sequence-function?relations for?small?RNA (sRNA)-mediated?gene?silencing?were quantified for?the?sRNA RyhB and some of its mRNA targets?in?Escherichia coli. Numerous mutants of RyhB and its targets were generated and their?in?vivo functions characterized at various levels of target and RyhB expression. Although a core complementary region is required for repression?by?RyhB, variations?in?the?complementary sequences of?the?core region gave rise to a continuum of repression strengths, correlated exponentially with?the?computed free energy of RyhB-target duplex formation. Moreover,?sequence?variations?inthe?linker region known to interact with?the?RNA chaperone Hfq also gave rise to a continuum of repression strengths, correlated exponentially with?thecomputed energy cost of keeping?the?linker region open. These results support?the?applicability of?the?thermodynamic model?in?predicting sRNA-mRNA interaction and suggest that sequences at these locations may be used to fine-tune?the?degree of repression. Surprisingly, a truncated RyhB without?the?Hfq-binding region is found to repress multiple targets of?the?wild-type RyhB effectively, both?in?the?presence and absence of Hfq, even though?the?former is required for?the?activity of wild-type RyhB itself. These findings challenge?the?commonly accepted model concerning?the?function?of Hfq?in?gene?silencing-bothin?providing stability to?the?sRNAs and?in?catalyzing?the?target mRNAs to take on active conformations-and raise?the?intriguing question of why many endogenous sRNAs subject their functions to Hfq-dependences.

submitted time 2016-05-08 Hits1986Downloads802 Comment 0

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