The projection constant for the trace class

Fuente: arXiv
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Hauptverfasser: Defant, Andreas, Galicer, Daniel, Mansilla, Martín, Mastyło, Mieczysław, Muro, Santiago
Format: Preprint
Veröffentlicht: 2023
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author Defant, Andreas
Galicer, Daniel
Mansilla, Martín
Mastyło, Mieczysław
Muro, Santiago
author_facet Defant, Andreas
Galicer, Daniel
Mansilla, Martín
Mastyło, Mieczysław
Muro, Santiago
contents We study the projection constant of the space of operators on $n$-dimensional Hilbert spaces, with the trace norm, $\mathcal S_1(n)$. We show an integral formula for the projection constant of $\mathcal S_1(n)$; namely $ \boldsymbolλ\big(\mathcal S_1(n)\big) = n \int_{\mathcal U_n} \vert \text{tr}(U) \vert \,dU \,, $ where the integration is with respect to the Haar probability measure on the group $\mathcal U_n$ of unitary operators. Using a probabilistic approach, we derive the limit formula $ \lim_{n\to \infty} \boldsymbolλ\big(\mathcal S_1(n)\big)/n = \sqrtπ/2\,. $
format Preprint
id arxiv_https___arxiv_org_abs_2302_00218
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle The projection constant for the trace class
Defant, Andreas
Galicer, Daniel
Mansilla, Martín
Mastyło, Mieczysław
Muro, Santiago
Functional Analysis
Metric Geometry
46B06, 46B07, 46G25 (Primary) 06E30, 30B50, 47B10, 43A15 (Secondary)
We study the projection constant of the space of operators on $n$-dimensional Hilbert spaces, with the trace norm, $\mathcal S_1(n)$. We show an integral formula for the projection constant of $\mathcal S_1(n)$; namely $ \boldsymbolλ\big(\mathcal S_1(n)\big) = n \int_{\mathcal U_n} \vert \text{tr}(U) \vert \,dU \,, $ where the integration is with respect to the Haar probability measure on the group $\mathcal U_n$ of unitary operators. Using a probabilistic approach, we derive the limit formula $ \lim_{n\to \infty} \boldsymbolλ\big(\mathcal S_1(n)\big)/n = \sqrtπ/2\,. $
title The projection constant for the trace class
topic Functional Analysis
Metric Geometry
46B06, 46B07, 46G25 (Primary) 06E30, 30B50, 47B10, 43A15 (Secondary)
url https://arxiv.org/abs/2302.00218