arXiv subjects

R. Kumar

Publications and source records attributed to R. Kumar.

240 records · Page 14Linked to original sources

arXiv2009

On free 4D Abelian 2-form and anomalous 2D Abelian 1-form gauge theories

We demonstrate a few striking similarities and some glaring differences between (i) the free four (3 + 1)-dimensional (4D) Abelian 2-form gauge theory, and (ii) the anomalous two (1 + 1)-dimensional (2D) Abelian 1-form gauge theory, within the framework of Becchi-Rouet-Stora-Tyutin (BRST) formalism. We demonstrate that the Lagrangian densities of the above two theories transform in a similar fashion under a set of symmetry transformations even though they are endowed with a drastically different variety of constraint structures. Taking the help of our understanding of the 4D Abelian 2-form gauge theory, we prove that the gauge invariant version of the anomalous 2D Abelian 1-form gauge theory is a new field-theoretic model for the Hodge theory where all the de Rham cohomological operators of differential geometry find their physical realizations in the language of proper symmetry transformations. The corresponding conserved charges obey an algebra that is reminiscent of the algebra of the cohomological operators. We briefly comment on the consistency of the 2D anomalous 1-form gauge theory in the language of restrictions on the harmonic state of the (anti-) BRST and (anti-) co-BRST invariant version of the above 2D theory.

hep-th↗

arXiv2008

Evidence for $B^0 \to χ_{c1} π^0$ at Belle

We present a measurement of the branching fraction for the Cabibbo- and color-suppressed $B^0 \to χ_{c1}π^0$ decay based on a data sample of $657\times 10^6$ $B\bar B$ events collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We observe a signal of $40\pm9$ events with a significance of $4.7σ$ including systematic uncertainties. The measured branching fraction is $\mathcal {B}(B^0 \to χ_{c1} π^0) = (1.12\pm 0.25(\rm {stat.})\pm 0.12({\rm syst.}))\times 10^{-5}$.

hep-ex↗

arXiv2008

Observation of $B^{\pm} \to ψ(2S) π^{\pm}$ and search for direct CP-violation

We report the first observation of $B^{\pm}\toψ(2S)π^{\pm}$, a Cabibbo- and color-suppressed decay. This analysis is based on $657\times10^{6}$ $B\overline B$ events collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB energy-asymmetric $e^+e^-$ collider. The measured branching fraction is ($2.44 \pm 0.22 \pm 0.20$)$\times 10^{-5}$ and the charge asymmetry is $\mathcal{A}=0.022 \pm 0.085 \pm 0.016$. The ratio of the branching fractions $\mathcal {B}(B^{\pm} \to ψ(2S) π^{\pm})$$/ \mathcal {B}(B^{\pm} \to ψ(2S) K^{\pm})$ $ = (3.99 \pm 0.36\pm 0.17)%$ is also determined.

hep-ex↗

arXiv2007

Alternative Method for Studying Color Centers in CsCl Thin Films

The optical properties of cesium chloride (CsCl) are changed with presence of vacancies in the crystal structure giving rise to what is called as "color centers". We have unconventionally adopted Tauc's method to determine the characteristic color centers and have modeled the correlation among the film optical properties and lattice size, highlighting the interrelation between the structural and optical properties of alkali halide films.

cond-mat.mtrl-sci↗

arXiv2006

Observation of B^{\pm} \to χ_{c1} π^{\pm} and Search for Direct CP Violation

We report the first observation of $B^{\pm} \to χ_{c1} π^{\pm}$, the Cabibbo- and color-suppressed decay in a data sample of $386\times 10^6$~$B\bar B$ events collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We observe $55\pm10$ signal events with a statistical significance of $6.3σ$ including systematic uncertainties. The measured branching fraction and charge-asymmetry is $\mathcal {B}(B^{\pm} \to χ_{c1} π^{\pm}) = (2.2\pm 0.4\pm 0.3)\times 10^{-5}$ and $\mathcal{A}_π = 0.07 \pm 0.18\pm 0.02$, respectively. We also determine the ratio $\mathcal {B}(B^{\pm} \to χ_{c1} π^{\pm})/\mathcal {B}(B^{\pm} \to χ_{c1} K^{\pm}) = (4.3\pm 0.8\pm 0.3) %$.

hep-ex↗

arXiv2005

Absence of M2 Retardation in $^{35}Cl$: Evidence for Stronger Isospin-Mixing Effects in A=35 Mirror Nuclei

The lifetime of the 3163 keV, 7/2$^-$ isomeric state in $^{35}Cl$ that decays by a stretched M2 transition to the $3/2^+$ ground state, has been re-measured using the Doppler Shift Attenuation Method, by gating on the 1185 keV transition which directly feeds this state. This eliminates the uncertainties in the measurement arising from the direct feedings from the continuum. A mean life of 0.6$^{+0.5}_{-0.2}$ ps has been obtained from the present work. This is considerably smaller than the adopted value 45.3(6) ps. Implication of this major reduction in the lifetime has been pointed out.

nucl-ex↗