共查询到20条相似文献,搜索用时 31 毫秒
1.
A.G. Akeroyd A. Arhrib Qi-Shu Yan 《The European Physical Journal C - Particles and Fields》2008,55(4):653-665
The charged Higgs boson decays H±→W±A1 and H±→W±Hi are studied in the framework of the next-to-minimal supersymmetric standard model (NMSSM). It is found that the decay rate
for H±→W±A1 can exceed the rates for the τ±ν and tb channels both below and above the top–bottom threshold. The dominance of H±→W±A1 is most readily achieved when A1 has a large doublet component and small mass. We also study the production process pp→H±A1 at the LHC followed by the decay H±→W±A1, which leads to the signature W±A1A1. We suggest that pp→H±A1 is a promising discovery channel for a light charged Higgs boson in the NMSSM with small or moderate tanβ and dominant decay
mode H±→W±A1. This W±A1A1 signature can also arise from the Higgsstrahlung process pp→W±H1 followed by the decay H1→A1A1. It is shown that there exist regions of parameter space where these processes can have comparable cross sections and we
suggest that their respective signals can be distinguished at the LHC by using appropriate reconstruction methods.
PACS 12.60.Fr; 14.80.Cp 相似文献
2.
C. Ruwiedel M. Schumacher N. Wermes 《The European Physical Journal C - Particles and Fields》2007,51(2):385-414
The prospects for the measurement of the tensor structure of the vertex between a standard model Higgs boson and two weak
gauge bosons using the distribution of the azimuthal angles between the two tagging jets in the weak boson fusion channel
are studied in a Monte Carlo analysis using the fast simulation of the ATLAS detector. The decay channels H→τ+τ-→ll+4ν, H→τ+τ-→lh+3ν at mH=120 GeV and H→W+W-→llνν at mH=160 GeV are used in the analysis. For a standard model Higgs boson it is found that purely anomalous couplings are expected
to be excluded at a confidence level corresponding to 2σ or more at mH=120 GeV and more than 5σ at mH=160 GeV from 30 fb-1 of data. With a value of 1 roughly reproducing the standard model cross section for a purely anomalous coupling, the standard
deviation in a measurement of a contribution of a CP even anomalous coupling in addition to the standard model coupling is
estimated to be 0.20 at mH=120 GeV and 0.09 at mH=160 GeV. 相似文献
3.
《The European Physical Journal C - Particles and Fields》2008,54(1):61-72
Results of background measurements with a prototype of the Borexino detector were used to search for 478 keV solar axions
emitted in the M1-transitions of 7Li*. The Compton conversion of axion to a photon A+e→e+γ, axioelectric effect A+e+Z→e+Z, decay of axion in two photons A→2γ and
Primakoff conversion on nuclei A+Z→γ+Z are considered. The upper limit on constants of interaction of axion with electrons,
photons and nucleons – gAegAN≤(1.0–2.4)×10-10 at mA≤450 keV and gAγgAN≤5×10-9 GeV-1 at mA≤10 keV are obtained (90%c.l.). For heavy axions with mass at 100<mA<400 keV the limits gAe<(0.7–2.0)×10-8 and gAγ<10-9–10-8 are obtained in assumption that gAN depends on mA as for KSVZ axion model. These limits are stronger than obtained in previous laboratory-based experiments using nuclear reactor
and artificial radioactive sources.
PACS 14.80.Mz; 29.40.Mc; 26.65.+t 相似文献
4.
The top-pions (Πt
0,±) and the top-Higgs (ht
0) are the typical particles predicted by the topcolor-assisted technicolor (TC2) model and the observation of these particles
can be regarded as direct evidence of the TC2 model. In this paper, we study three pair production processes of these new
particles at the next generation eγ colliders, i.e., e-γ→e-Πt
+Πt
-, e-γ→νeΠt
-Πt
0 and e-γ→νeΠt
-ht
0. The results show that the production rates can reach the level 100–101 fb with reasonable parameter values. So one can expect that enough signals could be produced in future high- energy linear
collider experiments. Furthermore, the flavor-changing (FC) decay modes Πt
-→bc̄, Πt
0(ht
0)→tc̄ can provide us with the typical signal to detect these new particles.
PACS 12.60Nz; 14.80.Mz; 12.15.LK; 14.65.Ha 相似文献
5.
Ahmed Ali Fernando Barreiro Javier Llorente 《The European Physical Journal C - Particles and Fields》2011,71(9):1737
We present an analysis with improved sensitivity to the light charged Higgs (mH+ < mt-mbm_{H^{+}} < m_{t}-m_{b}) searches in the top quark decays t→bH
+→b(τ
+
ν
τ
)+c.c. in the t[`(t)]t\bar{t} and single t/[`(t)]t/\bar{t} production processes at the LHC. In the Minimal Supersymmetric Standard Model (MSSM), one anticipates the branching ratio
B (H+ ?t+nt) @ 1{\mathcal{B}} (H^{+} \to\tau^{+}\nu_{\tau})\simeq1 over almost the entire allowed tanb\tan\beta range. Noting that the τ
+ arising from the decay H
+→τ
+
ν
τ
are predominantly right-polarized, as opposed to the τ
+ from the dominant background W
+→τ
+
ν
τ
, which are left-polarized, a number of H
+/W
+→τ
+
ν
τ
discriminators have been proposed and studied in the literature. We consider hadronic decays of the τ
±, concentrating on the dominant one-prong decay channel τ
±→ρ
±
ν
τ
. The energy and p
T
of the charged prongs normalised to the corresponding quantities of the ρ
± are convenient variables which serve as τ
± polariser. We use the distributions in these variables and several other kinematic quantities to train a boosted decision
tree (BDT). Using the BDT classifier, and a variant of it called BDTD, which makes use of decorrelated variables, we have
calculated the BDT(D)-response functions to estimate the signal efficiency vs. the rejection of the background. We argue that
this chain of analysis has a high sensitivity to light charged Higgs searches up to a mass of 150 GeV in the decays t→bH
+ (and charge conjugate) at the LHC. For the case of single top production, we also study the transverse mass of the system
determined using Lagrange multipliers. 相似文献
6.
In this paper the charged Higgs signal through the decay to a pair of muon and neutrino (H
±→μν) is analyzed. The analysis attempts to estimate the amount of muonic signal of the charged Higgs at LHC at a center of mass
energy of 14 TeV. The signal process is the top quark pair production with one of the top quarks decaying to a charged Higgs
(non SM anomalous top decay) and the other decaying to a W boson which is assumed to decay hadronically to two light jets.
Due to the small branching ratio of charged Higgs decay to muon, results are quoted for data corresponding to an integrated
luminosity of 300 fb−1 which is expected to be collected at the LHC high luminosity regime. It is shown that a signal significance close to 5σ down to below 1σ is achievable for a charged Higgs mass in the range 80 GeV<m(H
±)<150 GeV taking the top quark pair production with both top quarks decaying to W bosons as the main irreducible background. 相似文献
7.
Using the data of about 33 pb-1 collected at and around 3.773 GeV with the BES-II detector at the BEPC collider, we have studied the exclusive semileptonic
decays D+→K-π+e+νe, D0→K̄0π-e+νe, D+→K̄*0e+νe and D0→K*-e+νe. The absolute branching fractions for the decays are measured to be BF(D+→K-π+e+νe)=(3.50±0.75±0.27)%, BF(D0→K̄0π-e+νe)=(2.61±1.04±0.28)%, BF(D+→K̄*0e+νe)=(5.06±1.21±0.40)% and BF(D0→K*-e+νe)=(2.87±1.48±0.39)%. The ratio of the vector to pseudoscalar semileptonic decay rates Γ(D+→K̄*0e+νe)/Γ(D+→K̄0e+νe) is determined to be 0.57±0.17±0.02. 相似文献
8.
A. I. Shtern 《Russian Journal of Mathematical Physics》2011,18(2):211-215
Let G be a topological group. For a function f: G → ℝ and h ∈ G, the difference function Δ
h
f is defined by the rule Δ
h
f(x) = f(xh) − f(x) (x ∈ G). A function H: G → ℝ is said to be additive if it satisfies the Cauchy functional equation H(x + y) = H(x) + H(y) for every x, y ∈ G. A class F of real-valued functions defined on G is said to have the difference property if, for every function f: G → ℝ satisfying Δ
h
f ∈ F for each h ∈ G, there is an additive function H such that f − H ∈ F. Erdős’ conjecture claiming that the class of continuous functions on ℝ has the difference property was proved by N. G. de
Bruijn; later on, F. W. Carroll and F. S. Koehl obtained a similar result for compact Abelian groups and, under the additional
assumption that the other one-sided difference function ∇
h
f defined by ∇
h
f(x) = f(xh) − f(x) (x ∈ G, h ∈ G) is measurable for any h ∈ G, also for noncommutative compact metric groups. In the present paper, we consider a narrower class of groups, namely, the
family of semisimple compact connected Lie groups. It turns out that these groups admit a significantly stronger difference
property. Namely, if a function f: G → ℝ on a semisimple compact connected Lie group has continuous difference functions Δ
h
f for any h ∈ G (without the additional assumption concerning the measurability of the functions of the form ∇
h
f), then f is automatically continuous, and no nontrivial additive function of the form H is needed. Some applications are indicated, including difference theorems for homogeneous spaces of compact connected Lie
groups. 相似文献
9.
Results for the one-loop calculation of the decay width Γ(H→ggZ) in the standard model with Higgs boson masses in the range 115 GeV<m
H
<2m
W
are presented. We find that among all the helicity amplitudes contributing to the width only those for which the gluons have
the same polarization and the Z is longitudinally polarized contribute in any significant way. The calculation includes all contributions from the second
and third generations, and kinematic cuts to enhance the H→ggZ signal. Compared to the width of H→gg, we find Γ(H→ggZ)/Γ(H→gg)≲10−4. 相似文献
10.
J.M. Smillie 《The European Physical Journal C - Particles and Fields》2007,51(4):933-943
We study the extent to which spin assignments of new particles produced at the LHC can be deduced in the decay of a scalar
or fermion C into a new stable (or quasi-stable) particle A through the chain C→B±q, B±→AW±, W±→ℓ±νℓ where ℓ=e,μ. All possible spin assignments of the particles A and B are considered. Explicit invariant mass distributions
of the quark and lepton are given for each set of spins, valid for all masses. We also construct the asymmetry between the
chains with a W- and those with a W+. The Kullback–Leibler distance between the distributions is then calculated to give a quantitative measure of our ability
to distinguish the different spin assignments. 相似文献
11.
M. V. Zagidullin 《Optics and Spectroscopy》2010,109(4):538-542
In the temperature range of T = 150–400 K, the dependence of spectral widths (cm−1) on temperature, 182 + 0.38(±0.01)T and 217 + 0.48(±0.01)T, respectively, has been obtained for dimole emission of O2(a, 0) + O2(a, 0) → O2(X, 1) + O2(X, 0) + hν (λ = 703 nm) and O2(a, 0) + O2(a, 0) → O2(X, 0) + O2(X, 0) + hν (λ = 634 nm). It was shown that the ratio of dimole emission rate constants does not depend on temperature in the range
of 150–400 K and is 1.06 ± 0.01. 相似文献
12.
Absolute spectral luminosity from an O2–O2(a)-H2O gas flow formed by a chemical singlet oxygen generator was measured at 600–800 and 1230–1310 nm wavelengths. The results
were used to determine the rate constants for O2(a, 0) + O2(a, 0) → O2(X, 0) + O2(X, 0) + hν (λ = 634 nm) and O2(a, 0) + O2(a, 0) → O2(X, 1) + O2(X, 0) + hν (λ = 703 nm) collision-induced emission ((6.72 ± 0.8) × 10−23 and (7.17 ± 0.8) × 10−23 cm3/s, respectively). 相似文献
13.
Kenji Yajima 《Communications in Mathematical Physics》1999,208(1):125-152
Let be the two dimensional Schr?dinger operator with the real valued potential V which satisfies the decay condition at infinity for . We show that the wave operators , , are bounded in for any 1<p<∞ under the condition that H has no zero bound states or zero resonance, extending the corresponding results for higher dimensions. As W
± intertwine H
0 and the absolutely continuous part H P
ac of H : f(H)P
ac=W
±
f(H
0 )W
±
* for any Borel function f on ℝ1, this reduces the various L
p
-mapping properties of f(H)P
ac to those of f(H)0), the convolution operator by the Fourier transform of the function f(ξ2).
Received: 5 April 1999 / Accepted: 26 May 1999 相似文献
14.
M.R. Pennington T. Mori S. Uehara Y. Watanabe 《The European Physical Journal C - Particles and Fields》2008,56(1):1-16
We perform an amplitude analysis of the world published data on γγ→π+π- and π0π0. These are dominated in statistics by the recently published results from Belle on the charged pion channel. Nevertheless,
having only limited angular information, a range of solutions remain possible. We present two solutions with Γ(f0(980)→γγ)=0.42 and 0.10 keV, and Γ(f2(1270)→γγ)=3.14±0.20 and 3.82 ± 0.30 keV, respectively: the former being the solution favoured by χ2, the latter at the edge of acceptability. Models of the structure of the f0(980) predict two photon widths to be between 0.2 and 0.6 keV, depending on its composition as mainly K̄K, s̄s or qq̄qq. Presently
available data cannot yet distinguish unambiguously between these predictions. However, we show how forthcoming results on
γγ→π0π0 can not only discriminate between, but also refine, these classes of partial wave solutions. 相似文献
15.
Using a data sample of integrated luminosity of about 33 pb-1 collected around 3.773 GeV with the BESII detector at the BEPC collider, the semileptonic decays D+→φe+νe, D+→φμ+νμ and the hadronic decay D+→φπ+ are studied. The upper limits of the branching fractions are set to be BF(D+→φe+νe)<2.01% and BF(D+→φμ+νμ)<2.04% at the 90% confidence level. The ratio of the branching fractions for D+→φπ+ relative to D+→K-π+π+ is measured to be 0.057±0.011±0.003. In addition, the branching fraction for D+→φπ+ is obtained to be (5.2±1.0±0.4)×10-3. 相似文献
16.
Zhen-Jun Xiao Xin-Fen Chen Dong-Qin Guo 《The European Physical Journal C - Particles and Fields》2007,50(2):363-371
In this paper, we calculate the branching ratios and CP-violating asymmetries for Bs→ρ±K∓, ρ0K̄0 and ωK̄0 decays in the perturbative QCD factorization approach. The theoretical predictions for the CP-averaged branching ratios of
the considered decays are Br(Bs→ρ±K∓)≈24.7×10-6, Br(Bs→ρ0K̄0)≈1.2×10-7 and Br(Bs→ωK̄0)≈1.7×10-7; and we also predict large CP-violating asymmetries for the considered decay modes. Specifically, the large ACP
dir(Bs→ρ±K∓) at -12% level plus large branching ratio at 10-5 level are measurable in the forthcoming LHC-b experiments.
PACS 13.25.Hw; 12.38.Bx; 14.40.Nd 相似文献
17.
Robert Fleischer 《The European Physical Journal C - Particles and Fields》1999,6(3):451-470
A general parametrization of the B
+ → π
+
K
0 and B
d
0 → π
−
K
+ decay amplitudes is presented. It relies only on the isospin symmetry of strong interactions and the phase structure of the
Standard Model and involves no approximations. In particular, this parametrization takes into account both rescattering and
electroweak penguin effects, which limit the theoretical accuracy of bounds on γ arising from the combined B
+- → π
+-
K, B
d
→ π
∓
K
± branching ratios. Generalized bounds making also use of the CP asymmetry in the latter decay are derived, and their sensitivity
to possible rescattering and electroweak penguin effects is investigated. It is pointed out that experimental data on B
± → K
±
K allow us to include rescattering processes in these bounds completely, and an improved theoretical treatment of electroweak
penguins is presented. It is argued that rescattering effects may enhance the combined B
± → K
±
K branching ratio by a factor of O(10) to the 10−5 level, and that they may be responsible for the small present central value of the ratio of the combined B
d
→ π
∓
K
± and B
± → π
±
K branching ratios, which has recently been reported by the CLEO collaboration and, if confirmed, would exclude values of γ
within a large region around 90°. 相似文献
18.
A.M. El-Badry T. Kuroyanagi S. Mitarai A. Odahara Y. Gono S. Morinobu K. Ogawa 《The European Physical Journal A - Hadrons and Nuclei》1998,3(2):133-138
A recoil distance method was used to measure half-lives of the excited states of 145Sm. The reaction used was 139La(10B, 4n)145Sm. A plunger system was used. Half-lives were determined for two excited states for the first time. The yrast 27/2+ state was found to have a half-life of 1.1 ± 0.2 ns corresponding to the retardation of 3.1 × 10−4 comparing with the single particle estimate of M1. The excitation energy of this state was well reproduced by the shell model
calculation having a mixed configuration of [π{h11/2(g7/2)−2 (d5/2)−1}10−, νf7/2] + [π{h11/2(g7/2)−1}9−,νh9/2]. Another retarded E1 transition was also found in a decay of a 21/2+ state. Its retardation was 1.6 × 10−4 comparing with the single particle value.
Received: 9 September 1997 / Revised version: 12 June 1998 相似文献
19.
S.-H. Zhu 《The European Physical Journal C - Particles and Fields》2006,47(3):833-837
In this paper, we study the observability of an invisible Higgs boson at Fermilab Tevatron and CERN LHC through the production
channel qq̄→ZH→ℓ+ℓ-+P/T, where/PT is reconstructed from the ℓ+ℓ- with ℓ=e or μ. A new strategy is proposed to eliminate the largest irreducible background, namely qq̄→Z(→ℓ+ℓ-)Z(→νν̄). This strategy utilizes the precise measurements of qq̄→Z(→ℓ+ℓ-)Z(→ℓ+ℓ-). For mH=120 GeV and with luminosity 30 fb-1 at Tevatron, a 5σ observation of the invisible Higgs boson is possible. For mH=114∼140 GeV with only 10 fb-1 luminosity at LHC, a discovery signal over 5σ can be achieved.
PACS 14.80.Cp 相似文献
20.
X.-J. Wang J.-H. Jiang M.-L. Yan 《The European Physical Journal A - Hadrons and Nuclei》2002,14(2):219-224
In terms of effective field theory and mixed-propagator approach, we show that there is a larger hidden effect of isospin
breaking in ρ→πγ decay due to a ω exchange, ρ→ω→πγ. The branching ratio is predicted as B(ρ→πγ) = (11.67±2.0)×10-4, which is much larger than Particle Data Group's datum (6.8±1.7)×10-4 and one of charged mode, B(ρ±→π±γ) = (4.5±0.5)×10-4.
Received: 7 January 2002 / Accepted: 2 April 2002 相似文献