Sneha Malde

Abstract:

<jats:p>A novel measurement technique of strong-phase differences between the decay amplitudes of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msup><a:mi>D</a:mi><a:mn>0</a:mn></a:msup></a:math> and <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:msup><c:mrow><c:mover accent="true"><c:mrow><c:mi>D</c:mi></c:mrow><c:mrow><c:mo accent="true" stretchy="true">¯</c:mo></c:mrow></c:mover></c:mrow><c:mrow><c:mn>0</c:mn></c:mrow></c:msup></c:mrow></c:math> mesons is introduced which exploits quantum-correlated <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"><h:mrow><h:mi>D</h:mi><h:mrow><h:mover accent="true"><h:mrow><h:mi>D</h:mi></h:mrow><h:mrow><h:mo stretchy="true">¯</h:mo></h:mrow></h:mover></h:mrow></h:mrow></h:math> pairs produced by <l:math xmlns:l="http://www.w3.org/1998/Math/MathML" display="inline"><l:msup><l:mi>e</l:mi><l:mo>+</l:mo></l:msup><l:msup><l:mi>e</l:mi><l:mo>−</l:mo></l:msup></l:math> collisions at energies above the <n:math xmlns:n="http://www.w3.org/1998/Math/MathML" display="inline"><n:mi>ψ</n:mi><n:mo stretchy="false">(</n:mo><n:mn>3770</n:mn><n:mo stretchy="false">)</n:mo></n:math> production threshold, where <r:math xmlns:r="http://www.w3.org/1998/Math/MathML" display="inline"><r:mrow><r:mi>D</r:mi><r:mover accent="true"><r:mrow><r:mi>D</r:mi></r:mrow><r:mrow><r:mo stretchy="true">¯</r:mo></r:mrow></r:mover></r:mrow></r:math> pairs are produced in both even and odd eigenstates of the charge-conjugation symmetry. Employing this technique, the first determination of a <v:math xmlns:v="http://www.w3.org/1998/Math/MathML" display="inline"><v:mrow><v:msup><v:mrow><v:mi>D</v:mi></v:mrow><v:mrow><v:mn>0</v:mn></v:mrow></v:msup><v:mi>–</v:mi><v:msup><v:mrow><v:mover accent="true"><v:mrow><v:mi>D</v:mi></v:mrow><v:mrow><v:mo accent="true" stretchy="true">¯</v:mo></v:mrow></v:mover></v:mrow><v:mrow><v:mn>0</v:mn></v:mrow></v:msup></v:mrow></v:math> relative strong phase is reported with such data samples. The strong-phase difference between <ab:math xmlns:ab="http://www.w3.org/1998/Math/MathML" display="inline"><ab:mrow><ab:msup><ab:mrow><ab:mi>D</ab:mi></ab:mrow><ab:mrow><ab:mn>0</ab:mn></ab:mrow></ab:msup><ab:mo stretchy="false">→</ab:mo><ab:msup><ab:mrow><ab:mi>K</ab:mi></ab:mrow><ab:mrow><ab:mo>−</ab:mo></ab:mrow></ab:msup><ab:msup><ab:mrow><ab:mi>π</ab:mi></ab:mrow><ab:mrow><ab:mo>+</ab:mo></ab:mrow></ab:msup></ab:mrow></ab:math> and <db:math xmlns:db="http://www.w3.org/1998/Math/MathML" display="inline"><db:mrow><db:msup><db:mrow><db:mover accent="true"><db:mrow><db:mi>D</db:mi></db:mrow><db:mrow><db:mo accent="true" stretchy="true">¯</db:mo></db:mrow></db:mover></db:mrow><db:mrow><db:mn>0</db:mn></db:mrow></db:msup><db:mo stretchy="false">→</db:mo><db:msup><db:mrow><db:mi>K</db:mi></db:mrow><db:mrow><db:mo>−</db:mo></db:mrow></db:msup><db:msup><db:mrow><db:mi>π</db:mi></db:mrow><db:mrow><db:mo>+</db:mo></db:mrow></db:msup></db:mrow></db:math> decays, <jb:math xmlns:jb="http://www.w3.org/1998/Math/MathML" display="inline"><jb:msubsup><jb:mi>δ</jb:mi><jb:mrow><jb:mi>K</jb:mi><jb:mi>π</jb:mi></jb:mrow><jb:mi>D</jb:mi></jb:msubsup></jb:math>, is measured to be <lb:math xmlns:lb="http://www.w3.org/1998/Math/MathML" display="inline"><lb:msubsup><lb:mi>δ</lb:mi><lb:mrow><lb:mi>K</lb:mi><lb:mi>π</lb:mi></lb:mrow><lb:mi>D</lb:mi></lb:msubsup><lb:mo>=</lb:mo><lb:msup><lb:mrow><lb:mo stretchy="false">(</lb:mo><lb:msubsup><lb:mn>192.8</lb:mn><lb:mrow><lb:mo>−</lb:mo><lb:mn>12.4</lb:mn><lb:mo>−</lb:mo><lb:mn>2.4</lb:mn></lb:mrow><lb:mrow><lb:mo>+</lb:mo><lb:mn>11.0</lb:mn><lb:mo>+</lb:mo><lb:mn>1.9</lb:mn></lb:mrow></lb:msubsup><lb:mo stretchy="false">)</lb:mo></lb:mrow><lb:mo>∘</lb:mo></lb:msup></lb:math>, using a dataset corresponding to an integrated luminosity of <pb:math xmlns:pb="http://www.w3.org/1998/Math/MathML" display="inline"><pb:mn>7.13</pb:mn><pb:mtext> </pb:mtext><pb:mtext> </pb:mtext><pb:msup><pb:mi>fb</pb:mi><pb:mrow><pb:mo>−</pb:mo><pb:mn>1</pb:mn></pb:mrow></pb:msup></pb:math> collected at center-of-mass energies between 4.13–4.23 GeV by the BESIII experiment.</jats:p>

Abstract:

Using (2712 ± 14) × 106ψ(3686) events collected with the BESIII detector, we perform the first amplitude analysis of the radiative decay ψ3686→γKS0KS0$$ \psi (3686)\to \gamma {K}_S^0{K}_S^0 $$ within the mass region MKS0KS0<2.8$$ {M}_{K_S^0{K}_S^0}<2.8 $$ GeV/c2. Employing a one-channel K-matrix approach for the description of the dynamics of the KS0KS0$$ {K}_S^0{K}_S^0 $$ system, the data sample is well described with four poles for the f0-wave and three poles for the f2-wave. The determined pole positions are consistent with those of well-established resonance states. The observed f0 and f2 states are found to be in agreement with those produced in radiative J/ψ decays. The production behaviors of f0 and f2 poles in ψ3686→γKS0KS0$$ \psi (3686)\to \gamma {K}_S^0{K}_S^0 $$ are qualified with their residues and the converted branching fractions. By comparing with J/ψ→γKS0KS0$$ J/\psi \to \gamma {K}_S^0{K}_S^0 $$ decay, the ratios Bψ3686→γf0,2BJ/ψ→γf0,2$$ \frac{\mathcal{B}\left(\psi (3686)\to \gamma {f}_{0,2}\right)}{\mathcal{B}\left(J/\psi \to \gamma {f}_{0,2}\right)} $$ are determined, which provides crucial experimental inputs on the internal structure of the f0,2 states, especially their potential mixing with glueball components.

Abstract:

This article presents doubly differential measurements of the asymmetries in production rates between mesons containing a charm quark and those containing an anti-charm quark in proton-proton collisions at a centre-of-mass energy of s=13.6 TeV using data recorded by the LHCb experiment. The asymmetries of D0, D+ and Ds+ mesons are measured for two-dimensional intervals in transverse momentum and pseudorapidity, within the range 2.5 < pT< 25.0 GeV/c and 2.0 < η < 4.5. No significant production asymmetries are observed. Comparisons to the Pythia 8 and Herwig 7 event generators are also presented, and their agreement with the data is evaluated. These measurements constitute the first measurements of production asymmetries at this centre-of-mass energy of colliding beams, and the first measurements with the LHCb Run 3 detector.

Abstract:

A stringent test of $CP$ symmetry in hyperon decays is performed using $1.0\times {10}^{10}J/\psi$ events and $2.7\times {10}^9\psi (3686)$ events collected by the BESIII experiment. The $CP$ asymmetry in the two-body nonleptonic weak decays ${\mathrm{\Sigma }}^{+}\to p{\pi }^0$ and ${\overline{\mathrm{\Sigma }}}^{-}\to \overline{p}{\pi }^0$ is determined to be $A_{CP}=-0.0118\pm 0.0083(\mathrm{stat})\pm 0.0028(\mathrm{syst})$ , consistent with $CP$ conservation. The average decay parameter $⟨{\alpha }_0⟩=-0.9869\pm 0.0011(\mathrm{stat})\pm 0.0016(\mathrm{syst})$ represents the most precise measurement in the baryon sector to date. A model-independent analysis of the hyperon polarization is performed for the first time at $J/\psi$ and $\psi (3686)$ resonances, revealing a clear sign reversal and offering new insight into SU(3) symmetry breaking and baryon internal structure. These results provide the most stringent constraints on $CP$ violation in $\mathrm{\Sigma }$ decays and establish a benchmark for future precision studies.

Abstract:

Lepton number violation decay is searched for via using a data sample of events collected via the BESIII detector at the BEPCII collider. No significant signal is observed, and the upper limit on the branching fraction of at the 90% confidence level is determined for the first time to be .