1,296 research outputs found

### Factorization of Radiative Leptonic Decays of $B^-$ and $D^-$ Mesons Including the Soft Photon Region

In this work, we study the radiative leptonic decays of $B^-$ and $D^-$
mesons using factorization approach. Factorization is proved to be valid
explicitly at 1-loop level at any order of $O(\Lambda_{\rm
QCD}\left/m_Q\right.)$. We consider the contribution in the soft photon region
that $E_{\gamma} \sim \left. \Lambda^2_{\rm QCD} /\right. m_Q$. The numerical
results shows that, the soft photon region is very important for both the $B$
and $D$ mesons. The branching ratios of $B\to \gamma e\nu_e$ is $5.21\times
10^{-6}$, which is about $3$ times of the result obtained by only considering
the hard photon region $E_{\gamma}\sim m_Q$. And for the case of $D\to \gamma
e\nu_e$, the result of the branching ratio is $1.92\times 10^{-5}$.Comment: arXiv admin note: text overlap with arXiv:1409.035

### Factorization of Radiative Leptonic Decays of $B^-$ and $D^-$ Mesons

In this work, we study the factorization of the radiative leptonic decays of
$B^-$ and $D^-$ mesons, the contributions of the order $O(\Lambda _{\rm
QCD}\left/m_Q\right.)$ are taken into account. The factorization is proved to
be valid explicitly at the order $O(\alpha _s\Lambda _{\rm
QCD}\left/m_Q\right.)$. The hard kernel is obtained. The numerical results are
calculated using the wave-function obtained in relativistic potential model.
The $O(\Lambda _{\rm QCD}\left/m_Q\right.)$ contribution is found to be very
important, the correction to the decay amplitudes of $B^-\to \gamma e\bar{\nu}$
is about $20\% - 30\%$. For $D$ mesons, the $O(\Lambda _{\rm
QCD}\left/m_Q\right.)$ contributions are more important.Comment: 26 pages, 8 figures. Version to appear in Nucl. Phys.

### Constraints on anomalous quartic gauge couplings via $W\gamma jj$ production at the LHC

The vector boson scattering at the Large Hadron Collider (LHC) is sensitive
to anomalous quartic gauge couplings (aQGCs). In this paper, we investigate the
aQGC contribution to $W \gamma jj$ production at the LHC with $\sqrt{s}=13$
TeV in the context of an effective field theory (EFT). The unitarity bound is
applied as a cut on the energy scale of this production process, which is found
to have significant suppressive effects on the signals. To enhance the
statistical significance, we analyse the kinematic and polarization features of
the aQGC signals in detail. We find that the polarization effects induced by
the aQGCs are unique and can discriminate the signals from the SM backgrounds
well. With the proposed event selection strategy, we obtain the constraints on
the coefficients of dimension-8 operators with current luminosity. The results
indicate that the process $pp \to W \gamma jj$ is powerful for searching for
the $O_{M_{2,3,4,5}}$ and $O_{T_{5,6,7}}$ operators.Comment: 29 pages, 11 figures, 7 tables, to be published in Chinese Physics

### A Large-field J=1-0 Survey of CO and Its Isotopologues Toward the Cassiopeia A Supernova Remnant

We have conducted a large-field simultaneous survey of $^{12}$CO, $^{13}$CO,
and C$^{18}$O $J=1-0$ emission toward the Cassiopeia A (Cas A) supernova
remnant (SNR), which covers a sky area of $3.5^{\circ}\times3.1^{\circ}$. The
Cas giant molecular cloud (GMC) mainly consists of three individual clouds with
masses on the order of $10^4-10^5\ M_{\odot}$. The total mass derived from the
$\rm{^{13}CO}$ emission of the GMC is 2.1$\times10^{5}\ M_{\odot}$ and is
9.5$\times10^5\ M_{\odot}$ from the $\rm{^{12}CO}$ emission. Two regions with
broadened (6$-$7 km s$^{-1}$) or asymmetric $^{12}$CO line profiles are found
in the vicinity (within a 10$'\times10'$ region) of the Cas A SNR, indicating
possible interactions between the SNR and the GMC. Using the GAUSSCLUMPS
algorithm, 547 $^{13}$CO clumps are identified in the GMC, 54$\%$ of which are
supercritical (i.e. $\alpha_{\rm{vir}}<2$). The mass spectrum of the molecular
clumps follows a power-law distribution with an exponent of $-2.20$. The
pixel-by-pixel column density of the GMC can be fitted with a log-normal
probability distribution function (N-PDF). The median column density of
molecular hydrogen in the GMC is $1.6\times10^{21}$ cm$^{-2}$ and half the mass
of the GMC is contained in regions with H$_2$ column density lower than
$3\times10^{21}$ cm$^{-2}$, which is well below the threshold of star
formation. The distribution of the YSO candidates in the region shows no
agglomeration.Comment: 24 pages, 18 figure

### Radiative Leptonic Decays of the charged $B$ and $D$ Mesons Including Long-Distance Contribution

In this work we study the radiative leptonic decays of $B^-$, $D^-$ and
$D_s^-\to \gamma l \bar{\nu}$, including both the short-distance and
long-distance contributions. The short-distance contribution is calculated by
using the relativistic quark model, where the bound state wave function we used
is that obtained in the relativistic potential model. The long-distance
contribution is estimated by using vector meson dominance model.Comment: 8 pages, 4 figures, 3 table

### Standard Model of Particle Physics Violating Crypto-Nonlocal Realism

It has been well established that quantum mechanics (QM) violates Bell
inequalities (BI), which are consequences of local realism (LR). Remarkably QM
also violates Leggett inequalities (LI), which are consequences of a class of
nonlocal realism called crypto-nonlocal realism (CNR). Both LR and CNR assume
that measurement outcomes are determined by preexisting objective properties,
as well as hidden variables (HV) not considered in QM. We extend CNR and LI to
include the case that the measurement settings are not externally fixed, but
determined by hidden variables (HV). We derive a new version of LI, which is
then shown to be violated by entangled $B_d$ mesons, if
charge-conjugation-parity (CP) symmetry is indirectly violated, as indeed
established. The experimental result is quantitatively estimated by using the
indirect CP violation parameter, and the maximum of a suitably defined relative
violation is about $2.7\%$. Our work implies that standard model (SM) of
particle physics violates CNR. Our LI can also be tested in other systems such
as photon polarizations.Comment: 28 page

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