The observed rapid cooling of the neutron star (NS) located at the center of the supernova remnant Cassiopeia A (Cas A) can be explained in the minimal NS cooling scenario. This consequence may be ...changed if there exists an extra cooling source, such as axion emission. In this work, we study the Cas A NS cooling in the presence of axion emission, taking account of the temperature evolution in the whole life of the Cas A NS. We obtain a lower limit on the axion decay constant, fa≳(5−7)×108 GeV, if the star has an envelope with a thin carbon layer. This is as strong as existing limits imposed by other astrophysical observations such as SN1987A.
The extent of the stop coannihilation strip Ellis, John; Olive, Keith A.; Zheng, Jiaming
The European physical journal. C, Particles and fields,
07/2014, Letnik:
74, Številka:
7
Journal Article
Recenzirano
Odprti dostop
Many supersymmetric models such as the constrained minimal supersymmetric extension of the Standard Model (CMSSM) feature a strip in parameter space where the lightest neutralino
χ
is identified as ...the lightest supersymmetric particle, the lighter stop squark
t
~
1
is the next-to-lightest supersymmetric particle (NLSP), and the relic
χ
cold dark matter density is brought into the range allowed by astrophysics and cosmology by coannihilation with the lighter stop squark
t
~
1
NLSP. We calculate the stop coannihilation strip in the CMSSM, incorporating Sommerfeld enhancement effects, and we explore the relevant phenomenological constraints and phenomenological signatures. In particular, we show that the
t
~
1
may weigh several TeV, and its lifetime may be in the nanosecond range, features that are more general than the specific CMSSM scenarios that we study in this paper.
Supersymmetric grand unification based on SO(10) is one of the most attractive paradigms in physics beyond the Standard Model. Inspired by the recent NANOGrav signal, we discuss the implications of ...detecting a stochastic gravitational wave background emitted by a network of cosmic strings for the SO(10) grand unification. Starting from a minimal model with multiple steps of symmetry breaking, we show that it generally prefers a high intermediate scale above 1014 GeV that is favored by observable primordial gravitational waves. The observed spectrum can potentially narrow the possible range of the cosmic string scale and restricts the unified couplings and the unification scale by requiring gauge coupling unification. As an indirect consequence of the high cosmic string scale, the monopole abundance places nontrivial constraints on the theory. These are complementary to the proton decay constraints and probe different facets of supersymmetric SO(10) unification theories.
A
bstract
Non-supersymmetric SO(10) grand unified theories provide a framework in which the stability of dark matter is explained while gauge coupling unification is realized. In this work, we ...systematically study this possibility by classifying weakly interacting dark matter candidates in terms of their quantum numbers of SU(2)
L
⊗ U(1)
Y
,
B
−
L
, and SU(2)
R
. We consider both scalar and fermion candidates. We show that the requirement of a sufficiently high unification scale to ensure a proton lifetime compatible with experimental constraints plays a strong role in selecting viable candidates. Among the scalar candidates originating from either a
16
or
144
of SO(10), only SU(2)
L
singlets with zero hypercharge or doublets with
Y
= 1
/
2 satisfy all constraints for SU(4)
C
⊗ SU(2)
L
⊗ SU(2)
R
and SU(3)
C
⊗ SU(2)
L
⊗ SU(2)
R
⊗ U(1)
B
−
L
intermediate scale gauge groups. Among fermion triplets with zero hypercharge, only a triplet in the
45
with intermediate group SU(4)
C
⊗ SU(2)
L
⊗ SU(2)
R
leads to solutions with
M
GUT
> M
int
and a long proton lifetime. We find three models with weak doublets and
Y
= 1
/
2 as dark matter candidates for the SU(4)
C
⊗ SU(2)
L
⊗ SU(2)
R
and SU(4)
C
⊗ SU(2)
L
⊗ U(1)
R
intermediate scale gauge groups assuming a minimal Higgs content. We also discuss how these models may be tested at accelerators and in dark matter detection experiments.
Future electron-positron colliders will play a leading role in the precision measurement of Higgs boson couplings which is one of the central interests in particle physics. Aiming at maximizing the ...performance to measure the Higgs couplings to the bottom, charm and strange quarks, we develop machine learning methods to improve the selection of events with a Higgs decaying to dijets. Our methods are based on the Boosted Decision Tree (BDT), Fully-Connected Neural Network (FCNN) and Convolutional Neural Network (CNN). We find that the BDT and FCNN algorithms outperform the conventional cut-based method. With our improved selection of Higgs decaying to dijet events using the FCNN, the charm quark signal strength is measured with a 16% error, which is roughly a factor of two better than the 34% precision obtained by the cut-based analysis. Also, the strange quark signal strength is constrained as μss≲35 at the 95% C.L. with the FCNN, which is to be compared with μss≲70 obtained by the cut-based method.
Inspired by the 750 GeV diphoton state recently reported by ATLAS and CMS, we propose a U(1) sub()B-Lextension of the MSSM which predicts the existence of four spin zero resonance states that are ...degenerate in mass in the supersymmetric limit. Vectorlike fields, a gauge singlet field, as well as the MSSM Higgsinos are prevented from acquiring arbitrary large masses by a U(1) R symmetry. Indeed, these masses can be considerably lighter than the Z' gauge boson mass. Depending on kinematics, the resonance states could decay into right-handed neutrinos and sneutrinos, and/or MSSM Higgs fields and Higgsinos with total decay widths in the multi-GeV range.
Stop coannihilation may bring the relic density of heavy supersymmetric dark matter particles into the range allowed by cosmology. The efficiency of this process is enhanced by stop-antistop ...annihilations into the longitudinal (Goldstone) modes of the
W
and
Z
bosons, as well as by Sommerfeld enhancement of stop annihilations and the effects of bound states. Since the couplings of the stops to the Goldstone modes are proportional to the trilinear soft supersymmetry-breaking
A
-terms, these annihilations are enhanced when the
A
-terms are large. However, the Higgs mass may be reduced below the measured value if the
A
-terms are too large. Unfortunately, the interpretation of this constraint on the stop coannihilation strip is clouded by differences between the available Higgs mass calculators. For our study, we use as our default calculator FeynHiggs 2.13.0, the most recent publicly available version of this code. Exploring the CMSSM parameter space, we find that along the stop coannihilation strip the masses of the stops are severely split by the large
A
-terms. This suppresses the Higgs mass drastically for
μ
and
A
0
>
0
, whilst the extent of the stop coannihilation strip is limited for
A
0
<
0
and either sign of
μ
. However, in sub-GUT models, reduced renormalization-group running mitigates the effect of the large
A
-terms, allowing larger LSP masses to be consistent with the Higgs mass calculation. We give examples where the dark matter particle mass may reach
≳
8
TeV.
Electroweak loop corrections to the matrix elements for the spin-independent scattering of cold dark matter particles on nuclei are generally small, typically below the uncertainty in the local ...density of cold dark matter. However, as shown in this paper, there are instances in which the electroweak loop corrections are relatively large, and change significantly the spin-independent dark matter scattering rate. An important example occurs when the dark matter particle is a wino, e.g., in anomaly-mediated supersymmetry breaking (AMSB) and pure gravity mediation (PGM) models. We find that the one-loop electroweak corrections to the spin-independent wino LSP scattering cross section generally interfere constructively with the tree-level contribution for AMSB models with negative Higgsino mixing,
μ
<
0
, and in PGM-like models for both signs of
μ
, lifting the cross section out of the neutrino fog and into a range that is potentially detectable in the next generation of direct searches for cold dark matter scattering.
One of the effective ways to control hypertension is long-term self-management, which is difficult to maintain. Therefore, understanding how people engage in the process of self-management behaviour ...change is necessary. In this study, we aimed to examine the dynamic relationship between self-perceived disease control and self-management behaviours in Chinese middle-aged and older hypertensive patients, namely, medication use, self-monitoring, physical activity, tobacco and alcohol avoidance, and to explore the mediating role of subjective life expectancy (SLE) on this relationship.
Data were obtained from a nationally representative sample of 508 middle-aged and older hypertensive patients (aged 45+) from the 2013, 2015, and 2018 waves of the Chinese Longitudinal Healthy Longevity Survey. A cross-lagged panel model combined with mediation analysis was used to determine the dynamic relationship between self-perceived disease control and self-management behaviours and to clarify the mediating effect of SLE on this ascertained relationship.
Good self-perceived disease control subsequently predicted good medication use, self-monitoring and physical activity, and vice versa. Subjective life expectancy (SLE) partially mediated the prospective reciprocal relationships between self-perceived disease control and these self-management behaviours, which accounted for 37.11, 25.88, and 19.39% of the total effect of self-perceived disease control on medication use, self-monitoring and physical activity, respectively. These self-management behaviours had a significant and positive feedback effect on self-perceived disease control. However, neither the direct and indirect effects (via SLE) of self-perceived disease control on tobacco and alcohol avoidance were revealed.
Positive feedback loops of present self-perceived disease control, future SLE and self-management behaviours (medication use, self-monitoring, and physical activity) help middle-aged and older hypertensive patients adhere to these behaviours but are useless for the avoidance of addictive behaviours. Interventions aimed at enhancing the effect perception of general self-management behaviours (e.g., medication use, self-monitoring and physical activity) on the present disease control perspective, and future lifespan perspective would be beneficial for the consistent self-management behaviours of middle-aged and older hypertensive patients. The utility of present disease control perception to these self-management behaviours was much higher than the utility of future expectations. Alternative stress relief strategies may be conducive to long-term changes in addictive behaviours.
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