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1.
R.P. Malik 《The European Physical Journal C - Particles and Fields》2006,47(1):227-234
We derive the off-shell nilpotent (anti-)BRST symmetry transformations for the interacting U(1) gauge theory of quantum electrodynamics
(QED) in the framework of the augmented superfield approach to the BRST formalism. In addition to the horizontality condition,
we invoke another gauge invariant condition on the six (4,2)-dimensional supermanifold to obtain the exact and unique nilpotent
symmetry transformations for all the basic fields present in the (anti-)BRST invariant Lagrangian density of the physical
four (3+1)-dimensional QED. The above supermanifold is parametrized by four even space–time variables
(with μ=0,1,2,3) and two odd variables (θ and
) of the Grassmann algebra. The new gauge invariant condition on the supermanifold owes its origin to the (super) covariant
derivatives and leads to the derivation of unique nilpotent symmetry transformations for the matter fields. The geometrical
interpretations for all the above off-shell nilpotent (anti-)BRST transformations are also discussed.
PACS 11.15.-q, 12.20.-m, 03.70.+k 相似文献
2.
A dynamical non-Abelian 2-form gauge theory (with B∧F term) is endowed with the “scalar” and “vector” gauge symmetry transformations. In our present endeavor, we exploit the latter
gauge symmetry transformations and perform the Becchi–Rouet–Stora–Tyutin (BRST) analysis of the four (3+1)-dimensional (4D)
topologically massive non-Abelian 2-form gauge theory. We demonstrate the existence of some novel features that have, hitherto,
not been observed in the context of BRST approach to 4D (non-)Abelian 1-form as well as Abelian 2-form and 3-form gauge theories.
We comment on the differences between the novel features that emerge in the BRST analysis of the “scalar” and “vector” gauge
symmetries. 相似文献
3.
Zhi-Qing Zhang Zhen-Jun Xiao 《The European Physical Journal C - Particles and Fields》2009,59(1):49-66
We calculate the important next-to-leading-order (NLO) contributions to the B→KK
* decays from the vertex corrections, the quark loops, and the magnetic penguins in the perturbative QCD (pQCD) factorization
approach. The pQCD predictions for the CP-averaged branching ratios are
,
,
and Br(B
0→K
+
K
*−+K
−
K
*+)≈1.3×10−7, which agree well with both the experimental upper limits and the predictions based on the QCD factorization approach. Furthermore,
the CP violating asymmetries of the considered decay modes are also evaluated. The NLO pQCD predictions for
and
decays are
and
. 相似文献
4.
R.P. Malik 《The European Physical Journal C - Particles and Fields》2008,55(4):687-698
We discuss various symmetry properties of the Lagrangian density of a four- (3+1)-dimensional (4D) free Abelian 2-form gauge
theory within the framework of Becchi–Rouet–Stora–Tyutin (BRST) formalism. The present free Abelian gauge theory is endowed
with a Curci–Ferrari type condition, which happens to be a key signature of the 4D non-Abelian 1-form gauge theory. In fact,
it is due to the above condition that the nilpotent BRST and anti-BRST symmetries of our present theory are found to be absolutely anticommuting in nature. For the present 2-form theory, we discuss the BRST, anti-BRST, ghost and discrete symmetry properties
of the Lagrangian densities and derive the corresponding conserved charges. The algebraic structure, obeyed by the above conserved
charges, is deduced and the constraint analysis is performed with the help of physicality criteria, where the conserved and
nilpotent (anti-) BRST charges play completely independent roles. These physicality conditions lead to the derivation of the above Curci–Ferrari type restriction, within the framework
of the BRST formalism, from the constraint analysis.
PACS 11.15.-q; 12.20.-m; 03.70.+k 相似文献
5.
R.P. Malik 《The European Physical Journal C - Particles and Fields》2007,51(1):169-177
We provide an alternative to the gauge covariant horizontality condition, which is responsible for the derivation of the nilpotent (anti-) BRST symmetry transformations for
the gauge and (anti-) ghost fields of a (3+1)-dimensional (4D) interacting 1-form non-Abelian gauge theory in the framework
of the usual superfield approach to the Becchi–Rouet–Stora–Tyutin (BRST) formalism. The above covariant horizontality condition
is replaced by a gauge invariant restriction on the (4,2)-dimensional supermanifold, parameterised by a set of four spacetime coordinates, xμ(μ=0,1,2,3), and a pair of Grassmannian variables, θ and θ̄. The latter condition enables us to derive the nilpotent (anti-)
BRST symmetry transformations for all the fields of an interacting 1-form 4D non-Abelian gauge theory in which there is an explicit coupling between the gauge
field and the Dirac fields. The key differences and the striking similarities between the above two conditions are pointed
out clearly.
PACS 11.15.-q; 12.20.-m; 03.70.+k 相似文献
6.
R. P. Malik 《Physics of Particles and Nuclei Letters》2011,8(3):244-250
We derive absolutely anticommuting Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST symmetry transformations for the 4D free
Abelian 2-form gauge theory by exploiting the superfield approach to BRST formalism. The antisymmetric tensor gauge field
of the above theory was christened as the “notoph” (i.e. the opposite of “photon”) gauge field by Ogievetsky and Palubarinov
way back in 1966–67. We briefly outline the problems involved in obtaining the absolute anticonimutativity of the (anti-)
BRST transformations and their resolution within the framework of geometrical superfield approach to BRST formalism. One of
the highlights of our results is the emergence of a Curci-Ferrari type of restriction in the context of 4D Abelian 2-form
(notoph) gauge theory which renders the nilpotent (anti-) BRST symmetries of the theory to be absolutely anticommutative in
nature. 相似文献
7.
Alexey S. Koshelev Sergey Yu. Vernov 《The European Physical Journal C - Particles and Fields》2012,72(10):1-14
We clearly and consistently supersymmetrize the celebrated horizontality condition to derive the off-shell nilpotent and absolutely anticommuting Becchi?CRouet?CStora?CTyutin (BRST) and anti-BRST symmetry transformations for the supersymmetric system of a free spinning relativistic particle within the framework of superfield approach to BRST formalism. For the precise determination of the proper (anti-)BRST symmetry transformations for all the bosonic and fermionic dynamical variables of our system, we consider the present theory on a (1,2)-dimensional supermanifold parameterized by an even (bosonic) variable (??) and a pair of odd (fermionic) variables ?? and $\bar{\theta}$ (with $\theta^{2} = \bar{\theta}^{2} = 0$ , $\theta\bar{\theta}+ \bar{\theta}\theta= 0$ ) of the Grassmann algebra. One of the most important and novel features of our present investigation is the derivation of (anti-)BRST invariant Curci?CFerrari type restriction which turns out to be responsible for the absolute anticommutativity of the (anti-)BRST transformations and existence of the coupled (but equivalent) Lagrangians for the present theory of a supersymmetric system. These observations are completely new results for this model. 相似文献
8.
Chong-Xing Yue Wei Wang Zheng-Jun Zong Feng Zhang 《The European Physical Journal C - Particles and Fields》2005,42(3):331-339
In the framework of the littlest Higgs (LH) model, we consider the processes
and
, and we calculate the contributions of new particles to the cross sections of these processes in the future high energy e + e- collider (ILC) with
TeV. We find that, with reasonable values of the free parameters, the deviations of the cross sections for the processes
from their SM values might be comparable to the future ILC measurement precision. The contributions of the light Higgs boson H0 to the process
are significantly large in all of the parameter space preferred by the electroweak precision data, which might be detected in the future ILC experiments. However, the contributions of the new gauge bosons BH and ZH to this process are very small.Received: 22 February 2005, Revised: 27 April 2005, Published online: 6 July 2005PACS:
12.60.Cn, 14.70.Pw, 14.80.Cp 相似文献
9.
G. Abbiendi et al. 《The European Physical Journal C - Particles and Fields》2006,45(2):307-335
The mass and width of the W boson are measured using e+e– → W+W– events from the data sample collected by the OPAL experiment at LEP at centre-of-mass energies between 170 GeV and 209 GeV.
The mass (mW) and width (ΓW) are determined using direct reconstruction of the kinematics of W+W– →
and W+W– →
events. When combined with previous OPAL measurements using W+W– →
events and the dependence on of the WW production cross-section at threshold, the results are determined to be
where the first error is statistical, the second systematic and the third due to uncertainties in the value of the LEP beam
energy. By measuring in the channel using several different determinations of the direction of jets with differing sensitivities
to soft particles, a limit is also obtained on possible final-state interactions due to colour reconnection effects inW+W– →
events. The consistency of the results for the W mass and width with those inferred from other electroweak parameters provides
an important test of the Standard Model of electroweak interactions.
Arrival of the final proofs: 28 November 2005
This paper is dedicated to the memory of Steve O'Neale 相似文献
10.
R. P. Malik 《Physics of Particles and Nuclei》2012,43(5):669-672
We discuss a D-dimensional Abelian 3-form gauge theory within the framework of Bonora-Tonin’s superfield formalism and derive the off-shell nilpotent and absolutely anticommuting Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST symmetry transformations for this theory. To pay our homage to Victor I. Ogievetsky (1928–1996), who was one of the inventors of Abelian 2-form (antisymmetric tensor) gauge field, we go a step further and discuss the above D-dimensional Abelian 3-form gauge theory within the framework of BRST formalism and establish that the existence of the (anti-)BRST invariant Curci-Ferrari (CF) type of restrictions is the hallmark of any arbitrary p-form gauge theory (discussed within the framework of BRST formalism). 相似文献
11.
Xiang Liu Zhi-Gang Luo Yan-Rui Liu Shi-Lin Zhu 《The European Physical Journal C - Particles and Fields》2009,61(3):411-428
We perform a systematic study of the possible molecular states composed of a pair of heavy mesons such as
,
,
in the framework of the meson exchange model. The exchanged mesons include the pseudoscalar, scalar and vector mesons. Through
our investigation, we find the following results. (1) The structure X(3764) is not a molecular state. (2) There exists strong attraction in the range r<1 fm for the
system with J=0,1. If future experiments confirm Z
+(4051) as a loosely bound molecular state, its quantum number is probably J
P
=0+. Its partner state Φ
**0 may be searched for in the π
0
χ
c1 channel. (3) Vector meson exchange provides strong attraction in the
channel together with pion exchange. A bound state solution may exist with a reasonable cutoff parameter Λ∼1.4 GeV. X(3872) may be accommodated as a molecular state dynamically although drawing a very definite conclusion needs further investigation.
(4) The
molecular state may exist. 相似文献
12.
We analyze the extraction of weak phases from CP-violation in B → π+π- decays. We propose to determine the unitarity triangle
by combining the information on mixing-induced CP-violation in B → π+π-, S, with the precision observable sin2β obtained from the CP-asymmetry in B → ψKS. It is then possible to write down exact analytical expressions for
and
as simple functions of the observables S and sin2β and of the penguin parameters r and ϕ. As an application clean lower bounds on
and
can be derived as functions of S and sin2β, essentially without hadronic uncertainty. Computing r and ϕ within QCD factorization yields precise determinations of
and
since the dependence on r and ϕ is rather weak. It is emphasized that the sensitivity to the phase ϕ enters only at second order and is extremely small
for moderate values of this phase, predicted in the heavy-quark limit. Transparent analytical formulas are further given and
discussed for the parameter C of direct CP-violation in B → π+π-. Predictions and uncertainties for r and ϕ in QCD factorization are examined in detail. It is pointed out that a simultaneous expansion in 1/mb and 1/N leads to interesting simplifications. At first order infrared divergences are absent, while the most important effects are
retained. Independent experimental tests of the factorization framework are briefly discussed.
Received: 16 April 2005, Revised: 6 August 2005, Published online: 21 November 2005
PACS:
11.30.Er, 12.15.Hh, 13.25.Hw 相似文献
13.
Anthony R. Timmins 《The European Physical Journal C - Particles and Fields》2009,62(1):249-254
We report STAR measurements of mid-rapidity yields for the Λ ,
, K
S
0 , Ξ
−,
, Ω
−,
particles in Cu + Cu and Au + Au
GeV collisions. We show that at a given number of participating nucleons, bulk strangeness production is higher in Cu + Cu
collisions compared to Au + Au collisions at the same center of mass energy, counter to predictions from the Canonical formalism.
We compare both the Cu + Cu and Au + Au yields to AMPT and EPOS predictions, and find they reproduce key qualitative aspects
of the data. Finally, we investigate other scaling parameters and find bulk strangeness production for both the measured data
and theoretical predictions, scales better with the number participants that undergo more than one collision. 相似文献
14.
Shao-Long Chen Xiao-Gang He Xue-Peng Hu Yi Liao 《The European Physical Journal C - Particles and Fields》2009,60(2):317-321
An unparticle
with scaling dimension
has peculiar thermal properties due to its unique phase space structure. We find that the equation of state parameter
, the ratio of pressure to energy density, is given by
providing a new form of energy in our universe. In an expanding universe, the unparticle energy density
evolves dramatically differently from that for photons. For
, even if
at a high decoupling temperature T
D is very small, it is possible to have a large relic density
at present photon temperature T
γ
0, large enough to play the role of dark matter. We calculate T
D and
using photon–unparticle interactions for illustration. 相似文献
15.
In the context of the littlest Higgs (LH) model, we study the process
. We find that the new gauge bosons Z
H
and B
H
can produce significant correction effects on this process, which can be further enhanced by suitably polarized beams. In most of the parameter space preferred by the electroweak precision data, the absolute value of the relative correction parameter
is larger than 5 %. As long as
and
the absolute value of the relative correction parameter
is larger than
. With reasonable values of the parameters of the LH model, the possible signals of the new gauge bosons B
H
and Z
H
can be detected via the process
in the future LC experiments with the CM energy
. B
H
exchange and Z
H
exchange can generate significantly corrections to the forward-backward asymmetry
only in a small part of the parameter space.Received: 29 October 2004, Revised: 29 November 2004, Published online: 15 February 2005 相似文献
16.
17.
A search for pair-produced charged Higgs bosons was performed in the data collected by the DELPHI detector at LEP II at centre-of-mass energies from 189 GeV to 209 GeV. Five different final states,
,
,
,
and
were considered, accounting for the major expected decays in type I and type II Two Higgs Doublet Models. No significant excess of data compared to the expected Standard Model processes was observed. The existence of a charged Higgs boson with mass lower than 76.7 GeV/c2 (type I) or 74.4 GeV/c2 (type II) is excluded at the 95% confidence level, for a wide range of the model parameters. Model independent cross-section limits have also been calculated.Received: 30 September 2003, Revised: 12 February 2004, Published online: 8 April 2004 相似文献
18.
We prove the collinear factorization theorem for the process
at the twist-3 level in the covariant gauge by means of the Ward identity, concentrating on the two-parton case. It is shown that soft divergences cancel and collinear divergences are grouped into the pseudo-scalar and pseudo-tensor two-parton twist-3 pion distribution amplitudes. The delicate summation of a complete set of diagrams for achieving factorization in momentum, spin, and color spaces is emphasized. The proof is then extended to the exclusive semileptonic decay
, assuming the hard scale to be of
, where
is a hadronic scale and M
B
the B meson mass. We explain the distinction between the factorization of collinear divergences for a pion distribution amplitude and of soft divergences for a B meson distribution amplitude. The gauge invariance and universality of the two-parton twist-3 pion distribution amplitudes are confirmed. The proof presented here can accommodate the leading twist-2 case. We then compare our proof with that performed in the framework of soft-collinear effective theory.Received: 8 June 2004, Revised: 10 December 2004, Published online: 3 March 2005PACS:
12.38.Bx 相似文献
19.
Measurements of on-shell ZZ production are described, using data from the DELPHI experiment at LEP in e
+
e
- collisions at centre-of-mass energies between 183 and 209 GeV, corresponding to an integrated luminosity of about 665 pb-1. Results obtained in each of the final states
,
,
,
,
, l
+
l
-
l
+
l
-, and
(with
) are presented. The measured production cross-sections are consistent with the Standard Model expectations. These results update and supersede those already published at 183 and 189 GeV.Received: 3 March 2002, Revised: 28 May 2003, Published online: 19 September 2003 相似文献
20.
We present the non-Abelian gaugings of supermembranes for general isometries for compactifications from eleven-dimensions,
starting with an Abelian case as a guide. We introduce a super Killing vector in eleven-dimensional superspace for a non-Abelian
group G associated with the compact space B for a general compactification, and couple it to a non-Abelian gauge field on the world-volume. As a technical tool, we use
teleparallel superspace with no manifest local Lorentz covariance. Interestingly, the coupling constant is quantized for the
non-Abelian group G, due to its non-trivial mapping
.
Received: 15 September 2004, Revised: 12 November 2004, Published online: 14 January 2005
PACS:
11.25.Mj, 11.25.Tq, 04.50. + h, 04.65. + e 相似文献