Maria T. Grosse Perdekamp

Triangle Singularity as the Origin of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>a</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow></mml:msub><mml:mo stretchy="false">(</mml:mo><mml:mn>1420</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:math>

Physical Review Letters · 2021 · 34 citations

The COMPASS Collaboration experiment recently discovered a new isovector resonancelike signal with axial-vector quantum numbers, the a_{1}(1420), decaying to f_{0}(980)π. With a mass too close to and a width smaller than the axial-vector ground state a_{1}(1260), it was immediately interpreted as a new light exotic meson, similar to the X, Y, Z states in the hidden-charm sector. We show that a resonancelike signal fully matching the experimental data is produced by the decay of the a_{1}(1260) r…

Measurement of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>J</mml:mi><mml:mo>/</mml:mo><mml:mi>ψ</mml:mi></mml:mrow></mml:math>at forward and backward rapidity in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>p</mml:mi><mml:mo>+</mml:mo><mml:mi>p</mml:mi></mml:mrow></mml:math>,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>p</mml:mi><mml:mo>+</mml:mo><mml:mi>Al</mml:mi></mml:mrow></mml:math>,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>p</mml:mi><mml:mo>+</mml:mo><mml:mi>Au</mml:mi></mml:mrow></mml:math>, and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mmultiscripts><mml:mi>He</mml:mi><mml:mprescripts/><mml:none/><mml:mn>3</mml:mn></mml:mmultiscripts><mml:mo>+</mml:mo><mml:mi>Au</mml:mi></mml:mrow></mml:math>collisions at<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msqrt><mml:msub><mml:mi>s</mml:mi><mml:mrow><mml:mi>N</mml:mi><mml:mi>N</mml:mi></mml:mrow></mml:msub></mml:msqrt><mml:mo>=</mml:mo><mml:mn>200</mml:mn></mml:mrow></mml:math>GeV

Physical review. C · 2020 · 25 citations

Charmonium is a valuable probe in heavy-ion collisions to study the properties of the quark gluon plasma, and is also an interesting probe in small collision systems to study cold nuclear matter effects, which are also present in large collision systems. With the recent observations of collective behavior of produced particles in small system collisions, measurements of the modification of charmonium in small systems have become increasingly relevant. We present the results of $J/\ensuremath{\ps…

Nuclear-modification factor of charged hadrons at forward and backward rapidity in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>p</mml:mi></mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>+</mml:mo></mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>Al</mml:mi></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>p</mml:mi></mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>+</mml:mo></mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>Au</mml:mi></mml:math> collisions at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msqrt><mml:msub><mml:mi>s</mml:mi><mml:mrow><mml:mi>N</mml:mi><mml:mi>N</mml:mi></mml:mrow></mml:msub></mml:msqrt><mml:mo>=</mml:mo><mml:mn>200</mml:mn><mml:mspace width="0.16em"/><mml:mi>GeV</mml:mi></mml:mrow></mml:math>

Physical review. C · 2020 · 24 citations

The PHENIX experiment has studied nuclear effects in $p+\mathrm{Al}$ and $p+\mathrm{Au}$ collisions at $\sqrt{{s}_{{}_{NN}}}=200\phantom{\rule{0.16em}{0ex}}\mathrm{GeV}$ on charged hadron production at forward rapidity ($1.4&lt;\ensuremath{\eta}&lt;2.4$, $p$-going direction) and backward rapidity ($\ensuremath{-}2.2&lt;\ensuremath{\eta}&lt;\ensuremath{-}1.2$, $A$-going direction). Such effects are quantified by measuring nuclear modification factors as a function of transverse momentum and pseud…

Measurement of the cross section for hard exclusive $\\pi^0$ muoproduction on the proton

Physics Letters B · 2020 · 23 citations

We report on a measurement of hard exclusive $\pi^0$ muoproduction on the proton by COMPASS using 160 GeV/$c$ polarised $\mu^+$ and $\mu^-$ beams of the CERN SPS impinging on a liquid hydrogen target. From the average of the measured $\mu^+$ and $\mu^-$ cross sections, the virtual-photon proton cross section is determined as a function of the squared four-momentum transfer between initial and final proton in the range $0.08\,(\text{GeV/}c)^2 < |t| < 0.64\,(\text{GeV/}c)^2$. The average kinematic…

Nonprompt direct-photon production in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mtext>Au</mml:mtext><mml:mo>+</mml:mo><mml:mtext>Au</mml:mtext></mml:mrow></mml:math> collisions at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msqrt><mml:msub><mml:mi>s</mml:mi><mml:mrow><mml:mi>N</mml:mi><mml:mi>N</mml:mi></mml:mrow></mml:msub></mml:msqrt><mml:mo>=</mml:mo><mml:mn>200</mml:mn></mml:mrow></mml:math> GeV

Physical review. C · 2024-04-18 · 14 citations

The measurement of the direct-photon spectrum from $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{{}_{NN}}}=200$ GeV is presented by the PHENIX Collaboration using the external-photon-conversion technique for 0%--93% central collisions in a transverse-momentum (${p}_{T}$) range of 0.8--10 $\text{GeV}/c$. An excess of direct photons, above prompt-photon production from hard-scattering processes, is observed for ${p}_{T}&lt;6\phantom{\rule{4pt}{0ex}}\text{GeV}/c$. Nonprompt direct photons are…